TY  - JOUR
A1  - Milewski, Robert
A1  - Chabrillat, Sabine
A1  - Behling, Robert
T1  - Analyses of Recent Sediment Surface Dynamic of a Namibian Kalahari Salt Pan Based on Multitemporal Landsat and Hyperspectral Hyperion Data
JF  - Remote Sensing
N2  - This study combines spaceborne multitemporal and hyperspectral data to analyze the spatial distribution of surface evaporite minerals and changes in a semi-arid depositional environment associated with episodic flooding events, the Omongwa salt pan (Kalahari, Namibia). The dynamic of the surface crust is evaluated by a change-detection approach using the Iterative-reweighted Multivariate Alteration Detection (IR-MAD) based on the Landsat archive imagery from 1984 to 2015. The results show that the salt pan is a highly dynamic and heterogeneous landform. A change gradient is observed from very stable pan border to a highly dynamic central pan. On the basis of hyperspectral EO-1 Hyperion images, the current distribution of surface evaporite minerals is characterized using Spectral Mixture Analysis (SMA). Assessment of field and image endmembers revealed that the pan surface can be categorized into three major crust types based on diagnostic absorption features and mineralogical ground truth data. The mineralogical crust types are related to different zones of surface change as well as pan morphology that influences brine flow during the pan inundation and desiccation cycles. These combined information are used to spatially map depositional environments where the more dynamic halite crust concentrates in lower areas although stable gypsum and calcite/sepiolite crusts appear in higher elevated areas.
KW  - salt pan
KW  - playa
KW  - hyperspectral
KW  - multitemporal
KW  - change detection
KW  - evaporite minerals
Y1  - 2016
U6  - https://doi.org/10.3390/rs9020170
SN  - 2072-4292
VL  - 9
IS  - 2
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Runge, Alexandra
A1  - Grosse, Guido
T1  - Mosaicking Landsat and Sentinel-2 Data to Enhance LandTrendr Time Series Analysis in Northern High Latitude Permafrost Regions
JF  - Remote Sensing
N2  - Permafrost is warming in the northern high latitudes, inducing highly dynamic thaw-related permafrost disturbances across the terrestrial Arctic. Monitoring and tracking of permafrost disturbances is important as they impact surrounding landscapes, ecosystems and infrastructure. Remote sensing provides the means to detect, map, and quantify these changes homogeneously across large regions and time scales. Existing Landsat-based algorithms assess different types of disturbances with similar spatiotemporal requirements. However, Landsat-based analyses are restricted in northern high latitudes due to the long repeat interval and frequent clouds, in particular at Arctic coastal sites. We therefore propose to combine Landsat and Sentinel-2 data for enhanced data coverage and present a combined annual mosaic workflow, expanding currently available algorithms, such as LandTrendr, to achieve more reliable time series analysis. We exemplary test the workflow for twelve sites across the northern high latitudes in Siberia. We assessed the number of images and cloud-free pixels, the spatial mosaic coverage and the mosaic quality with spectral comparisons. The number of available images increased steadily from 1999 to 2019 but especially from 2016 onward with the addition of Sentinel-2 images. Consequently, we have an increased number of cloud-free pixels even under challenging environmental conditions, which then serve as the input to the mosaicking process. In a comparison of annual mosaics, the Landsat+Sentinel-2 mosaics always fully covered the study areas (99.9–100 %), while Landsat-only mosaics contained data-gaps in the same years, only reaching coverage percentages of 27.2 %, 58.1 %, and 69.7 % for Sobo Sise, East Taymyr, and Kurungnakh in 2017, respectively. The spectral comparison of Landsat image, Sentinel-2 image, and Landsat+Sentinel-2 mosaic showed high correlation between the input images and mosaic bands (e.g., for Kurungnakh 0.91–0.97 between Landsat and Landsat+Sentinel-2 mosaic and 0.92–0.98 between Sentinel-2 and Landsat+Sentinel-2 mosaic) across all twelve study sites, testifying good quality mosaic results. Our results show that especially the results for northern, coastal areas was substantially improved with the Landsat+Sentinel-2 mosaics. By combining Landsat and Sentinel-2 data we accomplished to create reliably high spatial resolution input mosaics for time series analyses. Our approach allows to apply a high temporal continuous time series analysis to northern high latitude permafrost regions for the first time, overcoming substantial data gaps, and assess permafrost disturbance dynamics on an annual scale across large regions with algorithms such as LandTrendr by deriving the location, timing and progression of permafrost thaw disturbances
KW  - time series analysis
KW  - data fusion
KW  - disturbance tracking
KW  - permafrost
KW  - permafrost thaw
Y1  - 2020
U6  - https://doi.org/10.3390/rs12152471
SN  - 2072-4292
VL  - 12
IS  - 15
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Schäfer, Robin
A1  - Stede, Manfred
T1  - Argument mining on twitter
BT  - a survey
JF  - Information technology : it ; Methoden und innovative Anwendungen der Informatik und Informationstechnik ; Organ der Fachbereiche 3 und 4 der GI e.V. und des Fachbereichs 6 der ITG
N2  - In the last decade, the field of argument mining has grown notably. However, only relatively few studies have investigated argumentation in social media and specifically on Twitter. Here, we provide the, to our knowledge, first critical in-depth survey of the state of the art in tweet-based argument mining. We discuss approaches to modelling the structure of arguments in the context of tweet corpus annotation, and we review current progress in the task of detecting argument components and their relations in tweets. We also survey the intersection of argument mining and stance detection, before we conclude with an outlook.
KW  - Argument Mining
KW  - Twitter
KW  - Stance Detection
Y1  - 2021
U6  - https://doi.org/10.1515/itit-2020-0053
SN  - 1611-2776
SN  - 2196-7032
VL  - 63
IS  - 1
SP  - 45
EP  - 58
PB  - De Gruyter
CY  - Berlin
ER  - 
TY  - GEN
A1  - Runge, Alexandra
A1  - Grosse, Guido
T1  - Comparing Spectral Characteristics of Landsat-8 and Sentinel-2 Same-Day Data for Arctic-Boreal Regions
T2  - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe
N2  - The Arctic-Boreal regions experience strong changes of air temperature and precipitation regimes, which affect the thermal state of the permafrost. This results in widespread permafrost-thaw disturbances, some unfolding slowly and over long periods, others occurring rapidly and abruptly. Despite optical remote sensing offering a variety of techniques to assess and monitor landscape changes, a persistent cloud cover decreases the amount of usable images considerably. However, combining data from multiple platforms promises to increase the number of images drastically. We therefore assess the comparability of Landsat-8 and Sentinel-2 imagery and the possibility to use both Landsat and Sentinel-2 images together in time series analyses, achieving a temporally-dense data coverage in Arctic-Boreal regions. We determined overlapping same-day acquisitions of Landsat-8 and Sentinel-2 images for three representative study sites in Eastern Siberia. We then compared the Landsat-8 and Sentinel-2 pixel-pairs, downscaled to 60 m, of corresponding bands and derived the ordinary least squares regression for every band combination. The acquired coefficients were used for spectral bandpass adjustment between the two sensors. The spectral band comparisons showed an overall good fit between Landsat-8 and Sentinel-2 images already. The ordinary least squares regression analyses underline the generally good spectral fit with intercept values between 0.0031 and 0.056 and slope values between 0.531 and 0.877. A spectral comparison after spectral bandpass adjustment of Sentinel-2 values to Landsat-8 shows a nearly perfect alignment between the same-day images. The spectral band adjustment succeeds in adjusting Sentinel-2 spectral values to Landsat-8 very well in Eastern Siberian Arctic-Boreal landscapes. After spectral adjustment, Landsat and Sentinel-2 data can be used to create temporally-dense time series and be applied to assess permafrost landscape changes in Eastern Siberia. Remaining differences between the sensors can be attributed to several factors including heterogeneous terrain, poor cloud and cloud shadow masking, and mixed pixels.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 767 
KW  - spectral adjustment
KW  - northern high latitudes
KW  - permafrost
KW  - time series
KW  - optical data
KW  - surface reflectance
KW  - correlation
KW  - permafrost disturbances
KW  - land cover change
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-438660
SN  - 1866-8372
IS  - 767
ER  - 
TY  - JOUR
A1  - Yarman, Aysu
A1  - Scheller, Frieder W.
T1  - How reliable is the electrochemical readout of MIP sensors?
JF  - Sensors
N2  - Electrochemical methods offer the simple characterization of the synthesis of molecularly imprinted polymers (MIPs) and the readouts of target binding. The binding of electroinactive analytes can be detected indirectly by their modulating effect on the diffusional permeability of a redox marker through thin MIP films. However, this process generates an overall signal, which may include nonspecific interactions with the nonimprinted surface and adsorption at the electrode surface in addition to (specific) binding to the cavities. Redox-active low-molecular-weight targets and metalloproteins enable a more specific direct quantification of their binding to MIPs by measuring the faradaic current. The in situ characterization of enzymes, MIP-based mimics of redox enzymes or enzyme-labeled targets, is based on the indication of an electroactive product. This approach allows the determination of both the activity of the bio(mimetic) catalyst and of the substrate concentration.
KW  - molecularly imprinted polymers
KW  - electropolymerization
KW  - direct electron
KW  - transfer
KW  - catalysis
KW  - redox marker
KW  - gate effect
Y1  - 2020
U6  - https://doi.org/10.3390/s20092677
SN  - 1424-8220
VL  - 20
IS  - 9
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Picconi, David
T1  - Nonadiabatic quantum dynamics of the coherent excited state intramolecular proton transfer of 10-hydroxybenzo[h]quinoline
JF  - Photochemical & photobiological sciences
N2  - The photoinduced nonadiabatic dynamics of the enol-keto isomerization of 10-hydroxybenzo[h]quinoline (HBQ) are studied computationally using high-dimensional quantum dynamics. The simulations are based on a diabatic vibronic coupling Hamiltonian, which includes the two lowest pi pi* excited states and a n pi* state, which has high energy in the Franck-Condon zone, but significantly stabilizes upon excited state intramolecular proton transfer. A procedure, applicable to large classes of excited state proton transfer reactions, is presented to parametrize this model using potential energies, forces and force constants, which, in this case, are obtained by time-dependent density functional theory. The wave packet calculations predict a time scale of 10-15 fs for the photoreaction, and reproduce the time constants and the coherent oscillations observed in time- resolved spectroscopic studies performed on HBQ. In contrast to the interpretation given to the most recent experiments, it is found that the reaction initiated by 1 pi pi* <- S-0 photoexcitation proceeds essentially on a single potential energy surface, and the observed coherences bear signatures of Duschinsky mode-mixing along the reaction path. The dynamics after the 2 pi pi* <- S-0 excitation are instead nonadiabatic, and the n pi* state plays a major role in the relaxation process. The simulations suggest a mainly active role of the proton in the isomerization, rather than a passive migration assisted by the vibrations of the benzoquinoline backbone. <br /> [GRAPHICS] <br /> .
KW  - Excited state proton transfer
KW  - Quantum dynamics
KW  - Nonadiabatic effects
KW  - Spectroscopy
KW  - Coherences
Y1  - 2021
U6  - https://doi.org/10.1007/s43630-021-00112-z
SN  - 1474-905X
SN  - 1474-9092
VL  - 20
IS  - 11
SP  - 1455
EP  - 1473
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Neumann, Bettina
A1  - Wollenberger, Ulla
T1  - Electrochemical biosensors employing natural and artificial heme peroxidases on semiconductors
JF  - Sensors
N2  - Heme peroxidases are widely used as biological recognition elements in electrochemical biosensors for hydrogen peroxide and phenolic compounds. Various nature-derived and fully synthetic heme peroxidase mimics have been designed and their potential for replacing the natural enzymes in biosensors has been investigated. The use of semiconducting materials as transducers can thereby offer new opportunities with respect to catalyst immobilization, reaction stimulation, or read-out. This review focuses on approaches for the construction of electrochemical biosensors employing natural heme peroxidases as well as various mimics immobilized on semiconducting electrode surfaces. It will outline important advances made so far as well as the novel applications resulting thereof.
KW  - electrochemical biosensors
KW  - heme
KW  - peroxidases
KW  - semiconductors
KW  - peroxidase mimics
Y1  - 2020
U6  - https://doi.org/10.3390/s20133692
SN  - 1424-8220
VL  - 20
IS  - 13
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Perovic, Milena
A1  - Qin, Qing
A1  - Oschatz, Martin
T1  - From molecular precursors to nanoparticles
BT  - tailoring the adsorption properties of porous carbon materials by controlled chemical functionalization
JF  - Advanced functional materials
N2  - Nanoporous carbon materials (NCMs) provide the "function" of high specific surface area and thus have large interface area for interactions with surrounding species, which is of particular importance in applications related to adsorption processes. The strength and mechanism of adsorption depend on the pore architecture of the NCMs. In addition, chemical functionalization can be used to induce changes of electron density and/or electron density distribution in the pore walls, thus further modifying the interactions between carbons and guest species. Typical approaches for functionalization of nanoporous materials with regular atomic construction like porous silica, metal-organic frameworks, or zeolites, cannot be applied to NCMs due to their less defined local atomic construction and abundant defects. Therefore, synthetic strategies that offer a higher degree of control over the process of functionalization are needed. Synthetic approaches for covalent functionalization of NCMs, that is, for the incorporation of heteroatoms into the carbon backbone, are critically reviewed with a special focus on strategies following the concept "from molecules to materials." Approaches for coordinative functionalization with metallic species, and the functionalization by nanocomposite formation between pristine carbon materials and heteroatom-containing carbons, are introduced as well. Particular focus is given to the influences of these functionalizations in adsorption-related applications.
KW  - composites
KW  - heteroatoms
KW  - metal species
KW  - porous carbon materials
KW  - surface
KW  - functionalization
Y1  - 2020
U6  - https://doi.org/10.1002/adfm.201908371
SN  - 1616-301X
SN  - 1616-3028
VL  - 30
IS  - 41
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Gleiss, Alexander
A1  - Kohlhagen, Marco
A1  - Pousttchi, Key
T1  - An apple a day
BT  - how the platform economy impacts value creation in the healthcare market
JF  - Electronic markets : EM ; the international journal of electronic commerce and business media
N2  - The healthcare industry has been slow to adopt new technologies and practices. However, digital and data-enabled innovations diffuse the market, and the COVID-19 pandemic has recently emphasized the necessity of a fundamental digital transformation. Available research indicates the relevance of digital platforms in this process but has not studied their economic impact to date. In view of this research gap and the social and economic relevance of healthcare, we explore how digital platforms might affect value creation in this market with a particular focus on Google, Apple, Facebook, Amazon, and Microsoft (GAFAM). We rely on value network analyses to examine how GAFAM platforms introduce new value-creating roles and mechanisms in healthcare through their manifold products and services. Hereupon, we examine the GAFAM-impact on healthcare by scrutinizing the facilitators, activities, and effects. Our analyses show how GAFAM platforms multifacetedly untie conventional relationships and transform value creation structures in the healthcare market.
KW  - Digital platforms
KW  - Platform economy
KW  - Healthcare market
KW  - Digital health
KW  - GAFAM
KW  - Value network analysis
Y1  - 2021
U6  - https://doi.org/10.1007/s12525-021-00467-2
SN  - 1019-6781
SN  - 1422-8890
VL  - 31
IS  - 4
SP  - 849
EP  - 876
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Bußler, Sara
A1  - Rawel, Harshadrai Manilal
A1  - Schlüter, Oliver K.
T1  - Impact of plasma processed air (PPA) on phenolic model systems
BT  - suggested mechanisms and relevance for food applications
JF  - Innovative food science & emerging technologies : the official journal of the European Federation of Food Science and Technology
N2  - Cold plasma is considered to be a novel, non-thermal, chemical-free and eco-friendly disinfection and surface modification technology. Plasma treatment of air to generate the so called plasma processed air (PPA) induces the formation of reactive oxygen (ROS) and nitrogen species (RNS). As a result, PPA has a different chemical composition compared to untreated air and suits therefore as an alternative method for microbial disinfection. However, depending on the product properties of the food matrix and its composition, a number of plasmainduced reactions also need to be taken into consideration. 
This necessitates also the elucidation and understanding of the basic interactions of plasma species with bioactive compounds. The intention here is to avoid the degradation of these valuable substances and to prevent other undesirable effects in future food related applications.
In the present study, the effects of PPA treatment on selected antioxidants such as pyrocatechol and derivatives of hydroxycinnimic acid were investigated in model systems to specify possible reactions induced. Antioxidant capacity, pH value, UV-Vis spectroscopy, RP-HPLC and LC-MS analysis were applied to identify reaction products providing information on possible changes induced in food matrices by PPA treatment. 
Exposure to PPA caused a perceptible color change towards yellow-brown accompanied by a strong reduction of the pH and the formation of insoluble sediments in the model solutions. The accumulation of nitrate, nitrite, but not of hydrogen peroxide was shown. LC-MS analysis demonstrated the formation of plasma-modified derivatives in all tested systems. The main reactions in liquid model solutions exposed to PPA were attributed to oxidation, nitration and polymerization of the phenolic compounds.
KW  - cold atmospheric pressure plasma
KW  - reactive oxygen and nitrogen species
KW  - food safety
KW  - antioxidative phenolic ingredients
KW  - phenol oxidation
KW  - phenol nitration
KW  - plasma process indicators
Y1  - 2020
U6  - https://doi.org/10.1016/j.ifset.2020.102432
SN  - 1466-8564
SN  - 1878-5522
VL  - 64
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - GEN
A1  - Asgarimehr, Milad
A1  - Wickert, Jens
A1  - Reich, Sebastian
T1  - Evaluating impact of rain attenuation on space-borne GNSS Reflectometry wind speeds
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - The novel space-borne Global Navigation Satellite System Reflectometry (GNSS-R) technique has recently shown promise in monitoring the ocean state and surface wind speed with high spatial coverage and unprecedented sampling rate. The L-band signals of GNSS are structurally able to provide a higher quality of observations from areas covered by dense clouds and under intense precipitation, compared to those signals at higher frequencies from conventional ocean scatterometers. As a result, studying the inner core of cyclones and improvement of severe weather forecasting and cyclone tracking have turned into the main objectives of GNSS-R satellite missions such as Cyclone Global Navigation Satellite System (CYGNSS). Nevertheless, the rain attenuation impact on GNSS-R wind speed products is not yet well documented. Evaluating the rain attenuation effects on this technique is significant since a small change in the GNSS-R can potentially cause a considerable bias in the resultant wind products at intense wind speeds. Based on both empirical evidence and theory, wind speed is inversely proportional to derived bistatic radar cross section with a natural logarithmic relation, which introduces high condition numbers (similar to ill-posed conditions) at the inversions to high wind speeds. This paper presents an evaluation of the rain signal attenuation impact on the bistatic radar cross section and the derived wind speed. This study is conducted simulating GNSS-R delay-Doppler maps at different rain rates and reflection geometries, considering that an empirical data analysis at extreme wind intensities and rain rates is impossible due to the insufficient number of observations from these severe conditions. Finally, the study demonstrates that at a wind speed of 30 m/s and incidence angle of 30 degrees, rain at rates of 10, 15, and 20 mm/h might cause overestimation as large as approximate to 0.65 m/s (2%), 1.00 m/s (3%), and 1.3 m/s (4%), respectively, which are still smaller than the CYGNSS required uncertainty threshold. The simulations are conducted in a pessimistic condition (severe continuous rainfall below the freezing height and over the entire glistening zone) and the bias is expected to be smaller in size in real environments.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1132 
KW  - GNSS Reflectometry
KW  - wind speed
KW  - rain effect
KW  - rain attenuation
KW  - DDM simulation
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-473441
SN  - 1866-8372
IS  - 1132
ER  - 
TY  - GEN
A1  - Yarman, Aysu
A1  - Scheller, Frieder W.
T1  - How reliable is the electrochemical readout of MIP-sensors?
T2  - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2  - Electrochemical methods offer the simple characterization of the synthesis of molecularly imprinted polymers (MIPs) and the readouts of target binding. The binding of electroinactive analytes can be detected indirectly by their modulating effect on the diffusional permeability of a redox marker through thin MIP films. However, this process generates an overall signal, which may include nonspecific interactions with the nonimprinted surface and adsorption at the electrode surface in addition to (specific) binding to the cavities. Redox-active low-molecular-weight targets and metalloproteins enable a more specific direct quantification of their binding to MIPs by measuring the faradaic current. The in situ characterization of enzymes, MIP-based mimics of redox enzymes or enzyme-labeled targets, is based on the indication of an electroactive product. This approach allows the determination of both the activity of the bio(mimetic) catalyst and of the substrate concentration.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 960 
KW  - molecularly imprinted polymers
KW  - electropolymerization
KW  - direct electron transfer
KW  - catalysis
KW  - redox marker
KW  - gate effect
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-471608
SN  - 1866-8372
IS  - 960
ER  - 
TY  - GEN
A1  - Schulze, Sven
A1  - Wehrhold, Michel
A1  - Hille, Carsten
T1  - Femtosecond-pulsed laser written and etched fiber bragg gratings for fiber-optical biosensing
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - We present the development of a label-free, highly sensitive fiber-optical biosensor for online detection and quantification of biomolecules. Here, the advantages of etched fiber Bragg gratings (eFBG) were used, since they induce a narrowband Bragg wavelength peak in the reflection operation mode. The gratings were fabricated point-by-point via a nonlinear absorption process of a highly focused femtosecond-pulsed laser, without the need of prior coating removal or specific fiber doping. The sensitivity of the Bragg wavelength peak to the surrounding refractive index (SRI), as needed for biochemical sensing, was realized by fiber cladding removal using hydrofluoric acid etching. For evaluation of biosensing capabilities, eFBG fibers were biofunctionalized with a single-stranded DNA aptamer specific for binding the C-reactive protein (CRP). Thus, the CRP-sensitive eFBG fiber-optical biosensor showed a very low limit of detection of 0.82 pg/L, with a dynamic range of CRP detection from approximately 0.8 pg/L to 1.2 µg/L. The biosensor showed a high specificity to CRP even in the presence of interfering substances. These results suggest that the proposed biosensor is capable for quantification of CRP from trace amounts of clinical samples. In addition, the adaption of this eFBG fiber-optical biosensor for detection of other relevant analytes can be easily realized.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1073 
KW  - fiber Bragg gratings
KW  - ultra-fast laser inscription
KW  - fiber etching
KW  - nanostructure fabrication
KW  - fiber-optical sensors
KW  - aptamers
KW  - C-reactive
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-472692
SN  - 1866-8372
IS  - 1073
ER  - 
TY  - GEN
A1  - Coesfeld, Jacqueline
A1  - Anderson, Sharolyn J.
A1  - Baugh, Kimberly
A1  - Elvidge, Christopher D.
A1  - Schernthanner, Harald
A1  - Kyba, Christopher C. M.
T1  - Variation of individual location radiance in VIIRS DNB monthly composite images
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - With the growing size and use of night light time series from the Visible Infrared Imaging Radiometer Suite Day/Night Band (DNB), it is important to understand the stability of the dataset. All satellites observe differences in pixel values during repeat observations. In the case of night light data, these changes can be due to both environmental effects and changes in light emission. Here we examine the stability of individual locations of particular large scale light sources (e.g., airports and prisons) in the monthly composites of DNB data from April 2012 to September 2017. The radiances for individual pixels of most large light emitters are approximately normally distributed, with a standard deviation of typically 15-20% of the mean. Greenhouses and flares, however, are not stable sources. We observe geospatial autocorrelation in the monthly variations for nearby sites, while the correlation for sites separated by large distances is small. This suggests that local factors contribute most to the variation in the pixel radiances and furthermore that averaging radiances over large areas will reduce the total variation. A better understanding of the causes of temporal variation would improve the sensitivity of DNB to lighting changes.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1113 
KW  - artificial light at night
KW  - light pollution
KW  - night lights
KW  - VIIRS DNB
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-472326
SN  - 1866-8372
IS  - 1113
ER  - 
TY  - GEN
A1  - Eich, Susanne
A1  - Schmälzlin, Elmar
A1  - Löhmannsröben, Hans-Gerd
T1  - Distributed fiber optical sensing of oxygen with optical time domain reflectometry
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - In many biological and environmental applications spatially resolved sensing of molecular oxygen is desirable. A powerful tool for distributed measurements is optical time domain reflectometry (OTDR) which is often used in the field of telecommunications. We combine this technique with a novel optical oxygen sensor dye, triangular-[4] phenylene (TP), immobilized in a polymer matrix. The TP luminescence decay time is 86 ns. The short decay time of the sensor dye is suitable to achieve a spatial resolution of some meters. In this paper we present the development and characterization of a reflectometer in the UV range of the electromagnetic spectrum as well as optical oxygen sensing with different fiber arrangements.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1085 
KW  - OTDR
KW  - optical sensing
KW  - molecular oxygen
KW  - triangular-[4] phenylene
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-476659
SN  - 1866-8372
IS  - 1085
ER  - 
TY  - JOUR
A1  - Chen, Jie
A1  - Günther, Frank
A1  - Grosse, Guido
A1  - Liu, Lin
A1  - Lin, Hui
T1  - Sentinel-1 InSAR Measurements of Elevation Changes over Yedoma Uplands on Sobo-Sise Island, Lena Delta
JF  - Remote sensing
N2  - Yedoma-extremely ice-rich permafrost with massive ice wedges formed during the Late Pleistocene-is vulnerable to thawing and degradation under climate warming. Thawing of ice-rich Yedoma results in lowering of surface elevations. Quantitative knowledge about surface elevation changes helps us to understand the freeze-thaw processes of the active layer and the potential degradation of Yedoma deposits. In this study, we use C-band Sentinel-1 InSAR measurements to map the elevation changes over ice-rich Yedoma uplands on Sobo-Sise Island, Lena Delta with frequent revisit observations (as short as six or 12 days). We observe significant seasonal thaw subsidence during summer months and heterogeneous inter-annual elevation changes from 2016-17. We also observe interesting patterns of stronger seasonal thaw subsidence on elevated flat Yedoma uplands by comparing to the surrounding Yedoma slopes. Inter-annual analyses from 2016-17 suggest that our observed positive surface elevation changes are likely caused by the delayed progression of the thaw season in 2017, associated with mean annual air temperature fluctuations.
KW  - Sentinel-1 InSAR
KW  - Yedoma uplands
KW  - Sobo-Sise Island
KW  - summer heave
KW  - permafrost thaw subsidence
KW  - active layer
Y1  - 2018
U6  - https://doi.org/10.3390/rs10071152
SN  - 2072-4292
VL  - 10
IS  - 7
PB  - MDPI
CY  - Basel
ER  - 
TY  - GEN
A1  - Matthies, Christoph
T1  - Agile process improvement in retrospectives
T2  - 41st International Conference on Software Engineering: Companion Proceedings (ICSE-Companion)
N2  - Working in iterations and repeatedly improving team workflows based on collected feedback is fundamental to agile software development processes. Scrum, the most popular agile method, provides dedicated retrospective meetings to reflect on the last development iteration and to decide on process improvement actions. However, agile methods do not prescribe how these improvement actions should be identified, managed or tracked in detail. The approaches to detect and remove problems in software development processes are therefore often based on intuition and prior experiences and perceptions of team members. Previous research in this area has focused on approaches to elicit a team's improvement opportunities as well as measurements regarding the work performed in an iteration, e.g. Scrum burn-down charts. Little research deals with the quality and nature of identified problems or how progress towards removing issues is measured. In this research, we investigate how agile development teams in the professional software industry organize their feedback and process improvement approaches. In particular, we focus on the structure and content of improvement and reflection meetings, i.e. retrospectives, and their outcomes. Researching how the vital mechanism of process improvement is implemented in practice in modern software development leads to a more complete picture of agile process improvement.
KW  - Agile
KW  - Scrum
KW  - software process improvement
KW  - retrospective
Y1  - 2019
SN  - 978-1-7281-1764-5
SN  - 978-1-7281-1765-2
U6  - https://doi.org/10.1109/ICSE-Companion.2019.00063
SN  - 2574-1934
SN  - 2574-1926
SP  - 150
EP  - 152
PB  - IEEE
CY  - New York
ER  - 
TY  - GEN
A1  - Brand, Thomas
A1  - Giese, Holger
T1  - Generic adaptive monitoring based on executed architecture runtime model queries and events
T2  - IEEE Xplore
N2  - Monitoring is a key functionality for automated decision making as it is performed by self-adaptive systems, too. Effective monitoring provides the relevant information on time. This can be achieved with exhaustive monitoring causing a high overhead consumption of economical and ecological resources. In contrast, our generic adaptive monitoring approach supports effectiveness with increased efficiency. Also, it adapts to changes regarding the information demand and the monitored system without additional configuration and software implementation effort. The approach observes the executions of runtime model queries and processes change events to determine the currently required monitoring configuration. In this paper we explicate different possibilities to use the approach and evaluate their characteristics regarding the phenomenon detection time and the monitoring effort. Our approach allows balancing between those two characteristics. This makes it an interesting option for the monitoring function of self-adaptive systems because for them usually very short-lived phenomena are not relevant.
Y1  - 2019
SN  - 978-1-7281-2731-6
U6  - https://doi.org/10.1109/SASO.2019.00012
SN  - 1949-3673
SP  - 17
EP  - 22
PB  - IEEE
CY  - New York
ER  - 
TY  - GEN
A1  - Idzik, Krzysztof Ryszard
A1  - Cywinski, Piotr J.
A1  - Cranfield, Charles G.
A1  - Mohr, Gerhard J.
A1  - Beckert, Rainer
T1  - Molecular recognition of the antiretroviral drug Abacavir
BT  - towards the development of a novel carbazole-based fluorosensor
T2  - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2  - Due to their optical and electro-conductive attributes, carbazole derivatives are interesting materials for a large range of biosensor applications. In this study, we present the synthesis routes and fluorescence evaluation of newly designed carbazole fluorosensors that, by modification with uracil, have a special affinity for antiretroviral drugs via either Watson–Crick or Hoogsteen base pairing. To an N-octylcarbazole-uracil compound, four different groups were attached, namely thiophene, furane, ethylenedioxythiophene, and another uracil; yielding four different derivatives. Photophysical properties of these newly obtained derivatives are described, as are their interactions with the reverse transcriptase inhibitors such as abacavir, zidovudine, lamivudine and didanosine. The influence of each analyte on biosensor fluorescence was assessed on the basis of the Stern–Volmer equation and represented by Stern–Volmer constants. Consequently we have demonstrated that these structures based on carbazole, with a uracil group, may be successfully incorporated into alternative carbazole derivatives to form biosensors for the molecular recognition of antiretroviral drugs.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 847 
KW  - HIV
KW  - HAART
KW  - antiretroviral drugs
KW  - carbazole
KW  - base pairing
KW  - fluorescence spectroscopy
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-430372
SN  - 1866-8372
IS  - 847
SP  - 1195
EP  - 1204
ER  - 
TY  - CHAP
A1  - Lass, Sander
A1  - Bender, Benedict
T1  - Dedicated Data Sovereignty as Enabler for Platform-Based Business Models
T2  - Proceedings of the 2. Conference on Production Systems and Logistics
N2  - The digitalization of value networks holds out the prospect of many advantages for the participating compa- nies. Utilizing information platforms, cross-company data exchange enables increased efficiency of collab- oration and offers space for new business models and services. In addition to the technological challenges, the fear of know-how leakage appears to be a significant roadblock that hinders the beneficial realization of new business models in digital ecosystems. This paper provides the necessary building blocks of digital participation and, in particular, classifies the issue of trust creation within it as a significant success factor. Based on these findings, it presents a solution concept that, by linking the identified building blocks, offers the individual actors of the digital value network the opportunity to retain sovereignty over their data and know-how and to use the potential of extensive networking. In particular, the presented concept takes into account the relevant dilemma, that every actor (e. g. the machine users) has to be able to control his commu- nicated data at any time and have sufficient possibilities for intervention that, on the one hand, satisfy the need for protection of his knowledge and, on the other hand, do not excessively diminish the benefits of the system or the business. Taking up this perspective, this paper introduces dedicated data sovereignty and shows a possible implementation concept.
KW  - information gateway
KW  - data security
KW  - information flow control
KW  - platform acceptance
Y1  - 2021
U6  - https://doi.org/10.15488/11299
SP  - 382
EP  - 393
PB  - publish-Ing.
CY  - Hannover
ER  - 
TY  - JOUR
A1  - López de Guereñu Kurganova, Anna
A1  - Klier, Dennis Tobias
A1  - Haubitz, Toni
A1  - Kumke, Michael Uwe
T1  - Influence of Gd3+ doping concentration on the properties of Na(Y,Gd)F-4
BT  - Yb3+, Tm3+ upconverting nanoparticles and their long-term aging behavior
JF  - Photochemical & photobiological sciences / European Society for Photobiology
N2  - We present a systematic study on the properties of Na(Y,Gd)F-4-based upconverting nanoparticles (UCNP) doped with 18% Yb3+, 2% Tm3+, and the influence of Gd3+ (10-50 mol% Gd3+). UCNP were synthesized via the solvothermal method and had a range of diameters within 13 and 50 nm. Structural and photophysical changes were monitored for the UCNP samples after a 24-month incubation period in dry phase and further redispersion. Structural characterization was performed by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as dynamic light scattering (DLS), and the upconversion luminescence (UCL) studies were executed at various temperatures (from 4 to 295 K) using time-resolved and steady-state spectroscopy. An increase in the hexagonal lattice phase with the increase of Gd3+ content was found, although the cubic phase was prevalent in most samples. The Tm3+-luminescence intensity as well as the Tm3+-luminescence decay times peaked at the Gd3+ concentration of 30 mol%. Although the general upconverting luminescence properties of the nanoparticles were preserved, the 24-month incubation period lead to irreversible agglomeration of the UCNP and changes in luminescence band ratios and lifetimes.
KW  - Upconversion luminescence
KW  - Lanthanides
KW  - Near infra-red
KW  - Ultra-low
KW  - temperature
KW  - Time-resolved spectroscopy
Y1  - 2022
U6  - https://doi.org/10.1007/s43630-021-00161-4
SN  - 1474-905X
SN  - 1474-9092
VL  - 21
IS  - 2
SP  - 235
EP  - 245
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - GEN
A1  - Perovic, Milena
A1  - Qin, Qing
A1  - Oschatz, Martin
T1  - From molecular precursors to nanoparticles
BT  - tailoring the adsorption properties of porous carbon materials by controlled chemical functionalization
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Nanoporous carbon materials (NCMs) provide the "function" of high specific surface area and thus have large interface area for interactions with surrounding species, which is of particular importance in applications related to adsorption processes. The strength and mechanism of adsorption depend on the pore architecture of the NCMs. In addition, chemical functionalization can be used to induce changes of electron density and/or electron density distribution in the pore walls, thus further modifying the interactions between carbons and guest species. Typical approaches for functionalization of nanoporous materials with regular atomic construction like porous silica, metal-organic frameworks, or zeolites, cannot be applied to NCMs due to their less defined local atomic construction and abundant defects. Therefore, synthetic strategies that offer a higher degree of control over the process of functionalization are needed. Synthetic approaches for covalent functionalization of NCMs, that is, for the incorporation of heteroatoms into the carbon backbone, are critically reviewed with a special focus on strategies following the concept "from molecules to materials." Approaches for coordinative functionalization with metallic species, and the functionalization by nanocomposite formation between pristine carbon materials and heteroatom-containing carbons, are introduced as well. Particular focus is given to the influences of these functionalizations in adsorption-related applications.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1191 
KW  - composites
KW  - heteroatoms
KW  - metal species
KW  - porous carbon materials
KW  - surface functionalization
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-516140
SN  - 1866-8372
ER  - 
TY  - GEN
A1  - Yarman, Aysu
A1  - Scheller, Frieder W.
T1  - The first electrochemical MIP sensor for tamoxifen
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - We present an electrochemical MIP sensor for tamoxifen (TAM)-a nonsteroidal anti-estrogen-which is based on the electropolymerisation of an O-phenylenediamine. resorcinol mixture directly on the electrode surface in the presence of the template molecule. Up to now only. bulk. MIPs for TAM have been described in literature, which are applied for separation in chromatography columns. Electro-polymerisation of the monomers in the presence of TAM generated a film which completely suppressed the reduction of ferricyanide. Removal of the template gave a markedly increased ferricyanide signal, which was again suppressed after rebinding as expected for filling of the cavities by target binding. The decrease of the ferricyanide peak of the MIP electrode depended linearly on the TAM concentration between 1 and 100 nM. The TAM-imprinted electrode showed a 2.3 times higher recognition of the template molecule itself as compared to its metabolite 4-hydroxytamoxifen and no cross-reactivity with the anticancer drug doxorubucin was found. Measurements at + 1.1 V caused a fouling of the electrode surface, whilst pretreatment of TAM with peroxide in presence of HRP generated an oxidation product which was reducible at 0 mV, thus circumventing the polymer formation and electrochemical interferences.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1046 
KW  - molecularly imprinted polymers
KW  - anticancer drug
KW  - tamoxifen
KW  - electropolymerisation
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-476173
SN  - 1866-8372
IS  - 1046
ER  - 
TY  - GEN
A1  - Milewski, Robert
A1  - Chabrillat, Sabine
A1  - Behling, Robert
T1  - Analyses of Recent Sediment Surface Dynamic of a Namibian Kalahari Salt Pan Based on Multitemporal Landsat and Hyperspectral Hyperion Data
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - This study combines spaceborne multitemporal and hyperspectral data to analyze the spatial distribution of surface evaporite minerals and changes in a semi-arid depositional environment associated with episodic flooding events, the Omongwa salt pan (Kalahari, Namibia). The dynamic of the surface crust is evaluated by a change-detection approach using the Iterative-reweighted Multivariate Alteration Detection (IR-MAD) based on the Landsat archive imagery from 1984 to 2015. The results show that the salt pan is a highly dynamic and heterogeneous landform. A change gradient is observed from very stable pan border to a highly dynamic central pan. On the basis of hyperspectral EO-1 Hyperion images, the current distribution of surface evaporite minerals is characterized using Spectral Mixture Analysis (SMA). Assessment of field and image endmembers revealed that the pan surface can be categorized into three major crust types based on diagnostic absorption features and mineralogical ground truth data. The mineralogical crust types are related to different zones of surface change as well as pan morphology that influences brine flow during the pan inundation and desiccation cycles. These combined information are used to spatially map depositional environments where the more dynamic halite crust concentrates in lower areas although stable gypsum and calcite/sepiolite crusts appear in higher elevated areas.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 987 
KW  - salt pan
KW  - playa
KW  - hyperspectral
KW  - multitemporal
KW  - change detection
KW  - evaporite minerals
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-475642
SN  - 1866-8372
IS  - 987
ER  - 
TY  - JOUR
A1  - Liu, Yue
A1  - Gould, Oliver E. C.
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - On demand sequential release of (sub)micron particles controlled by size and temperature
JF  - Small : nano micro
N2  - Polymeric devices capable of releasing submicron particles (subMP) on demand are highly desirable for controlled release systems, sensors, and smart surfaces. Here, a temperature-memory polymer sheet with a programmable smooth surface served as matrix to embed and release polystyrene subMP controlled by particle size and temperature. subMPs embedding at 80 degrees C can be released sequentially according to their size (diameter D of 200 nm, 500 nm, 1 mu m) when heated. The differences in their embedding extent are determined by the various subMPs sizes and result in their distinct release temperatures. Microparticles of the same size (D approximate to 1 mu m) incorporated in films at different programming temperatures T-p (50, 65, and 80 degrees C) lead to a sequential release based on the temperature-memory effect. The change of apparent height over the film surface is quantified using atomic force microscopy and the realization of sequential release is proven by confocal laser scanning microscopy. The demonstration and quantification of on demand subMP release are of technological impact for assembly, particle sorting, and release technologies in microtechnology, catalysis, and controlled release.
KW  - on demand particle release
KW  - temperature-memory effect
KW  - thermosensitive
KW  - polymer surface
Y1  - 2022
U6  - https://doi.org/10.1002/smll.202104621
SN  - 1613-6810
SN  - 1613-6829
VL  - 18
IS  - 5
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - López-Salas, Nieves
A1  - Albero, Josep
T1  - CxNy
BT  - new carbon nitride organic photocatalysts
JF  - Frontiers in Materials
N2  - The search for metal-free and visible light-responsive materials for photocatalytic applications has attracted the interest of not only academics but also the industry in the last decades. Since graphitic carbon nitride (g-C3N4) was first reported as a metal-free photocatalyst, this has been widely investigated in different light-driven reactions. However, the high recombination rate, low electrical conductivity, and lack of photoresponse in most of the visible range have elicited the search for alternatives. In this regard, a broad family of carbon nitride (CxNy) materials was anticipated several decades ago. However, the attention of the researchers in these materials has just been awakened in the last years due to the recent success in the syntheses of some of these materials (i.e., C3N3, C2N, C3N, and C3N5, among others), together with theoretical simulations pointing at the excellent physico-chemical properties (i.e., crystalline structure and chemical morphology, electronic configuration and semiconducting nature, or high refractive index and hardness, among others) and optoelectronic applications of these materials. The performance of CxNy, beyond C3N4, has been barely evaluated in real applications, including energy conversion, storage, and adsorption technologies, and further work must be carried out, especially experimentally, in order to confirm the high expectations raised by simulations and theoretical calculations. Herein, we have summarized the scarce literature related to recent results reporting the synthetic routes, structures, and performance of these materials as photocatalysts. Moreover, the challenges and perspectives at the forefront of this field using CxNy materials are disclosed. We aim to stimulate the research of this new generation of CxNy-based photocatalysts, beyond C3N4, with improved photocatalytic efficiencies by harnessing the striking structural, electronic, and optical properties of this new family of materials.
KW  - CXNY
KW  - carbon nitrides
KW  - C2N
KW  - C3N
KW  - C1N1
KW  - C3N5
KW  - photocatalysis
Y1  - 2021
U6  - https://doi.org/10.3389/fmats.2021.772200
SN  - 2296-8016
VL  - 8
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Zhou, Yuefang
A1  - Kornher, Tristan
A1  - Mohnke, Janett
A1  - Fischer, Martin H.
T1  - Tactile interaction with a humanoid robot
BT  - effects on physiology and subjective impressions
JF  - International journal of social robotics
N2  - This study investigated how touching and being touched by a humanoid robot affects human physiology, impressions of the interaction, and attitudes towards humanoid robots. 21 healthy adult participants completed a 3 (touch style: touching, being touched, pointing) x 2 (body part: hand vs buttock) within-subject design using a Pepper robot. Skin conductance response (SCR) was measured during each interaction. Perceived impressions of the interaction (i.e., friendliness, comfort, arousal) were measured per questionnaire after each interaction. Participants' demographics and their attitude towards robots were also considered. We found shorter SCR rise times in the being touched compared to the touching condition, possibly reflecting psychological alertness to the unpredictability of robot-initiated contacts. The hand condition had shorter rise times than the buttock condition. Most participants evaluated the hand condition as most friendly and comfortable and the robot-initiated interactions as most arousing. Interacting with Pepper improved attitudes towards robots. Our findings require future studies with larger samples and improved procedures. They have implications for robot design in all domains involving tactile interactions, such as caring and intimacy.
KW  - Human– robot tactile interaction
KW  - Skin conductance
KW  - Buttocks
KW  - Robot Pepper
KW  - Human– robot intimate relationships
Y1  - 2021
U6  - https://doi.org/10.1007/s12369-021-00749-x
SN  - 1875-4791
SN  - 1875-4805
VL  - 13
IS  - 7
SP  - 1657
EP  - 1677
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Wehrhan, Marc
A1  - Sommer, Michael
T1  - A parsimonious approach to estimate soil organic carbon applying Unmanned Aerial System (UAS) multispectral imagery and the topographic position index in a heterogeneous soil landscape
JF  - Remote sensing / Molecular Diversity Preservation International (MDPI)
N2  - Remote sensing plays an increasingly key role in the determination of soil organic carbon (SOC) stored in agriculturally managed topsoils at the regional and field scales. Contemporary Unmanned Aerial Systems (UAS) carrying low-cost and lightweight multispectral sensors provide high spatial resolution imagery (<10 cm). These capabilities allow integrate of UAS-derived soil data and maps into digitalized workflows for sustainable agriculture. However, the common situation of scarce soil data at field scale might be an obstacle for accurate digital soil mapping. In our case study we tested a fixed-wing UAS equipped with visible and near infrared (VIS-NIR) sensors to estimate topsoil SOC distribution at two fields under the constraint of limited sampling points, which were selected by pedological knowledge. They represent all releva nt soil types along an erosion-deposition gradient; hence, the full feature space in terms of topsoils' SOC status. We included the Topographic Position Index (TPI) as a co-variate for SOC prediction. Our study was performed in a soil landscape of hummocky ground moraines, which represent a significant of global arable land. Herein, small scale soil variability is mainly driven by tillage erosion which, in turn, is strongly dependent on topography. Relationships between SOC, TPI and spectral information were tested by Multiple Linear Regression (MLR) using: (i) single field data (local approach) and (ii) data from both fields (pooled approach). The highest prediction performance determined by a leave-one-out-cross-validation (LOOCV) was obtained for the models using the reflectance at 570 nm in conjunction with the TPI as explanatory variables for the local approach (coefficient of determination (R-2) = 0.91; root mean square error (RMSE) = 0.11% and R-2 = 0.48; RMSE = 0.33, respectively). The local MLR models developed with both reflectance and TPI using values from all points showed high correlations and low prediction errors for SOC content (R-2 = 0.88, RMSE = 0.07%; R-2 = 0.79, RMSE = 0.06%, respectively). The comparison with an enlarged dataset consisting of all points from both fields (pooled approach) showed no improvement of the prediction accuracy but yielded decreased prediction errors. Lastly, the local MLR models were applied to the data of the respective other field to evaluate the cross-field prediction ability. The spatial SOC pattern generally remains unaffected on both fields; differences, however, occur concerning the predicted SOC level. Our results indicate a high potential of the combination of UAS-based remote sensing and environmental covariates, such as terrain attributes, for the prediction of topsoil SOC content at the field scale. The temporal flexibility of UAS offer the opportunity to optimize flight conditions including weather and soil surface status (plant cover or residuals, moisture and roughness) which, otherwise, might obscure the relationship between spectral data and SOC content. Pedologically targeted selection of soil samples for model development appears to be the key for an efficient and effective prediction even with a small dataset.
KW  - Unmanned Aerial System (UAS)
KW  - multispectral
KW  - Topographic Position Index
KW  - (TPI)
KW  - Multiple Linear Regression (MLR)
KW  - soil organic carbon (SOC)
KW  - agriculture
KW  - erosion
KW  - soil landscape
KW  - hummocky ground moraine
Y1  - 2021
U6  - https://doi.org/10.3390/rs13183557
SN  - 2072-4292
VL  - 13
IS  - 18
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Teichmann, Malte
A1  - Ullrich, André
A1  - Knost, Dennis
A1  - Gronau, Norbert
T1  - Serious games in learning factories
BT  - perpetuating knowledge in learning loops by game-based learning
JF  - Procedia manufacturing
N2  - The usage of gamification in the contexts of commerce, consumption, innovation or eLearning in schools and universities has been extensively researched. However, the potentials of serious games to transfer and perpetuate knowledge and action patterns in learning factories have not been levered so far. The goal of this paper is to introduce a serious game as an instrument for knowledge transfer and perpetuation. Therefore, reqirements towards serious games in the context of learning factories are pointed out. As a result, that builds on these requirements, a serious learning game for the topic of Industry 4.0 is practically designed and evaluated.
KW  - game-based learning
KW  - gamification
KW  - serious game
KW  - learning factories
Y1  - 2020
U6  - https://doi.org/10.1016/j.promfg.2020.04.104
SN  - 2351-9789
VL  - 45
SP  - 259
EP  - 264
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Dettmann, Sophie
A1  - Huittinen, Nina Maria
A1  - Nicolas, Jahn
A1  - Kretzschmar, Jerome
A1  - Kumke, Michael
A1  - Kutyma, Tamara
A1  - Lohmann, Janik
A1  - Reich, Tobias
A1  - Schmeide, Katja
A1  - Azzam, Salim Shams Aldin
A1  - Spittler, Leon
A1  - Stietz, Janina
T1  - Influence of gluconate on the retention of Eu(III), Am(III), Th(IV), Pu(IV), and U(VI) by C-S-H (C/S = 0.8)
JF  - Frontiers in Nuclear Engineering
N2  - The retention of actinides in different oxidation states (An(X), X = III, IV, VI) by a calcium-silicate-hydrate (C-S-H) phase with a Ca/Si (C/S) ratio of 0.8 was investigated in the presence of gluconate (GLU). The actinides considered were Am(III), Th(IV), Pu(IV), and U(VI). Eu(III) was investigated as chemical analogue for Am(III) and Cm(III). In addition to the ternary systems An(X)/GLU/C-S-H, also binary systems An(X)/C-S-H, GLU/C-S-H, and An(X)/GLU were studied. Complementary analytical techniques were applied to address the different specific aspects of the binary and ternary systems. Time-resolved laser-induced luminescence spectroscopy (TRLFS) was applied in combination with parallel factor analysis (PARAFAC) to identify retained species and to monitor species-selective sorption kinetics. ¹³C and ²⁹Si magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were applied to determine the bulk structure and the composition of the C-S-H surface, respectively, in the absence and presence of GLU. The interaction of Th(IV) with GLU in different electrolytes was studied by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS). The influence of GLU on An(X) retention was investigated for a large concentration range up to 10⁻² M. The results showed that GLU had little to no effect on the overall An(X) retention by C-S-H with C/S of 0.8, regardless of the oxidation state of the actinides. For Eu(III), the TRLFS investigations additionally implied the formation of a Eu(III)-bearing precipitate with dissolved constituents of the C-S-H phase, which becomes structurally altered by the presence of GLU. For U(VI) sorption on the C-S-H phase, only a small influence of GLU could be established in the luminescence spectroscopic investigations, and no precipitation of U(VI)-containing secondary phases could be identified.
KW  - actinide
KW  - organic ligand
KW  - sorption
KW  - cementitious material
KW  - concrete
KW  - luminescence
Y1  - 2023
U6  - https://doi.org/10.3389/fnuen.2023.1124856
SN  - 2813-3412
VL  - 2
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - GEN
A1  - Izgi, Gizem
A1  - Eibl, Eva P. S.
A1  - Donner, Stefanie
A1  - Bernauer, Felix
T1  - Performance Test of the Rotational Sensor blueSeis-3A in a Huddle Test in Fürstenfeldbruck
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Rotational motions play a key role in measuring seismic wavefield properties. Using newly developed portable rotational instruments, it is now possible to directly measure rotational motions in a broad frequency range. Here, we investigated the instrumental self-noise and data quality in a huddle test in Fürstenfeldbruck, Germany, in August 2019. We compare the data from six rotational and three translational sensors. We studied the recorded signals using correlation, coherence analysis, and probabilistic power spectral densities. We sorted the coherent noise into five groups with respect to the similarities in frequency content and shape of the signals. These coherent noises were most likely caused by electrical devices, the dehumidifier system in the building, humans, and natural sources such as wind. We calculated self-noise levels through probabilistic power spectral densities and by applying the Sleeman method, a three-sensor method. Our results from both methods indicate that self-noise levels are stable between 0.5 and 40 Hz. Furthermore, we recorded the 29 August 2019 ML 3.4 Dettingen earthquake. The calculated source directions are found to be realistic for all sensors in comparison to the real back azimuth. We conclude that the five tested blueSeis-3A rotational sensors, when compared with respect to coherent noise, self-noise, and source direction, provide reliable and consistent results. Hence, field experiments with single rotational sensors can be undertaken.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1150 
KW  - rotational seismology
KW  - huddle test
KW  - coherency
KW  - source direction
KW  - coherent noise
KW  - blueSeis-3A sensors
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-518556
SN  - 1866-8372
IS  - 1150
ER  - 
TY  - GEN
A1  - Runge, Alexandra
A1  - Grosse, Guido
T1  - Mosaicking Landsat and Sentinel-2 Data to Enhance LandTrendr Time Series Analysis in Northern High Latitude Permafrost Regions
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Permafrost is warming in the northern high latitudes, inducing highly dynamic thaw-related permafrost disturbances across the terrestrial Arctic. Monitoring and tracking of permafrost disturbances is important as they impact surrounding landscapes, ecosystems and infrastructure. Remote sensing provides the means to detect, map, and quantify these changes homogeneously across large regions and time scales. Existing Landsat-based algorithms assess different types of disturbances with similar spatiotemporal requirements. However, Landsat-based analyses are restricted in northern high latitudes due to the long repeat interval and frequent clouds, in particular at Arctic coastal sites. We therefore propose to combine Landsat and Sentinel-2 data for enhanced data coverage and present a combined annual mosaic workflow, expanding currently available algorithms, such as LandTrendr, to achieve more reliable time series analysis. We exemplary test the workflow for twelve sites across the northern high latitudes in Siberia. We assessed the number of images and cloud-free pixels, the spatial mosaic coverage and the mosaic quality with spectral comparisons. The number of available images increased steadily from 1999 to 2019 but especially from 2016 onward with the addition of Sentinel-2 images. Consequently, we have an increased number of cloud-free pixels even under challenging environmental conditions, which then serve as the input to the mosaicking process. In a comparison of annual mosaics, the Landsat+Sentinel-2 mosaics always fully covered the study areas (99.9–100 %), while Landsat-only mosaics contained data-gaps in the same years, only reaching coverage percentages of 27.2 %, 58.1 %, and 69.7 % for Sobo Sise, East Taymyr, and Kurungnakh in 2017, respectively. The spectral comparison of Landsat image, Sentinel-2 image, and Landsat+Sentinel-2 mosaic showed high correlation between the input images and mosaic bands (e.g., for Kurungnakh 0.91–0.97 between Landsat and Landsat+Sentinel-2 mosaic and 0.92–0.98 between Sentinel-2 and Landsat+Sentinel-2 mosaic) across all twelve study sites, testifying good quality mosaic results. Our results show that especially the results for northern, coastal areas was substantially improved with the Landsat+Sentinel-2 mosaics. By combining Landsat and Sentinel-2 data we accomplished to create reliably high spatial resolution input mosaics for time series analyses. Our approach allows to apply a high temporal continuous time series analysis to northern high latitude permafrost regions for the first time, overcoming substantial data gaps, and assess permafrost disturbance dynamics on an annual scale across large regions with algorithms such as LandTrendr by deriving the location, timing and progression of permafrost thaw disturbances
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1009 
KW  - time series analysis
KW  - data fusion
KW  - isturbance tracking
KW  - permafrost
KW  - permafrost thaw
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-480317
SN  - 1866-8372
IS  - 1009
ER  - 
TY  - JOUR
A1  - Vollbrecht, Joachim
A1  - Brus, Viktor V.
T1  - Effects of recombination order on open-circuit voltage decay measurements of organic and perovskite solar cells
JF  - Energies : open-access journal of related scientific research, technology development and studies in policy and management / Molecular Diversity Preservation International (MDPI)
N2  - Non-geminate recombination, as one of the most relevant loss mechanisms in organic and perovskite solar cells, deserves special attention in research efforts to further increase device performance. It can be subdivided into first, second, and third order processes, which can be elucidated by the effects that they have on the time-dependent open-circuit voltage decay. In this study, analytical expressions for the open-circuit voltage decay exhibiting one of the aforementioned recombination mechanisms were derived. It was possible to support the analytical models with experimental examples of three different solar cells, each of them dominated either by first (PBDBT:CETIC-4F), second (PM6:Y6), or third (irradiated CH3NH3PbI3) order recombination. Furthermore, a simple approach to estimate the dominant recombination process was also introduced and tested on these examples. Moreover, limitations of the analytical models and the measurement technique itself were discussed.
KW  - organic solar cells
KW  - perovskite solar cells
KW  - non-geminate recombination
KW  - recombination order
KW  - open-circuit voltage decay
Y1  - 2021
U6  - https://doi.org/10.3390/en14164800
SN  - 1996-1073
VL  - 14
IS  - 16
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Henkenjohann, Richard
T1  - Role of individual motivations and privacy concerns in the adoption of German electronic patient record apps
BT  - a mixed-methods study
JF  - International journal of environmental research and public health : IJERPH / Molecular Diversity Preservation International
N2  - Germany's electronic patient record ("ePA") launched in 2021 with several attempts and years of delay. The development of such a large-scale project is a complex task, and so is its adoption. Individual attitudes towards an electronic health record are crucial, as individuals can reject opting-in to it and making any national efforts unachievable. Although the integration of an electronic health record serves potential benefits, it also constitutes risks for an individual's privacy. With a mixed-methods study design, this work provides evidence that different types of motivations and contextual privacy antecedents affect usage intentions towards the ePA. Most significantly, individual motivations stemming from feelings of volition or external mandates positively affect ePA adoption, although internal incentives are more powerful.
KW  - personal electronic health records
KW  - technology adoption
KW  - endogenous
KW  - motivations
KW  - health information privacy concern
KW  - mixed-methods
KW  - ePA
Y1  - 2021
U6  - https://doi.org/10.3390/ijerph18189553
SN  - 1660-4601
VL  - 18
IS  - 18
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Caruccio, Loredana
A1  - Deufemia, Vincenzo
A1  - Naumann, Felix
A1  - Polese, Giuseppe
T1  - Discovering relaxed functional dependencies based on multi-attribute dominance
JF  - IEEE transactions on knowledge and data engineering
N2  - With the advent of big data and data lakes, data are often integrated from multiple sources. Such integrated data are often of poor quality, due to inconsistencies, errors, and so forth. One way to check the quality of data is to infer functional dependencies (fds). However, in many modern applications it might be necessary to extract properties and relationships that are not captured through fds, due to the necessity to admit exceptions, or to consider similarity rather than equality of data values. Relaxed fds (rfds) have been introduced to meet these needs, but their discovery from data adds further complexity to an already complex problem, also due to the necessity of specifying similarity and validity thresholds. We propose Domino, a new discovery algorithm for rfds that exploits the concept of dominance in order to derive similarity thresholds of attribute values while inferring rfds. An experimental evaluation on real datasets demonstrates the discovery performance and the effectiveness of the proposed algorithm.
KW  - Complexity theory
KW  - Approximation algorithms
KW  - Big Data
KW  - Distributed
KW  - databases
KW  - Semantics
KW  - Lakes
KW  - Functional dependencies
KW  - data profiling
KW  - data cleansing
Y1  - 2020
U6  - https://doi.org/10.1109/TKDE.2020.2967722
SN  - 1041-4347
SN  - 1558-2191
VL  - 33
IS  - 9
SP  - 3212
EP  - 3228
PB  - Institute of Electrical and Electronics Engineers
CY  - New York, NY
ER  - 
TY  - THES
A1  - Lindinger, Jakob
T1  - Variational inference for composite Gaussian process models
T1  - Variationelle Inferenz für zusammengesetzte Gauß-Prozess Modelle
N2  - Most machine learning methods provide only point estimates when being queried to predict on new data. This is problematic when the data is corrupted by noise, e.g. from imperfect measurements, or when the queried data point is very different to the data that the machine learning model has been trained with. Probabilistic modelling in machine learning naturally equips predictions with corresponding uncertainty estimates which allows a practitioner to incorporate information about measurement noise into the modelling process and to know when not to trust the predictions. A well-understood, flexible probabilistic framework is provided by Gaussian processes that are ideal as building blocks of probabilistic models. They lend themself naturally to the problem of regression, i.e., being given a set of inputs and corresponding observations and then predicting likely observations for new unseen inputs, and can also be adapted to many more machine learning tasks. However, exactly inferring the optimal parameters of such a Gaussian process model (in a computationally tractable manner) is only possible for regression tasks in small data regimes. Otherwise, approximate inference methods are needed, the most prominent of which is variational inference.
In this dissertation we study models that are composed of Gaussian processes embedded in other models in order to make those more flexible and/or probabilistic. The first example are deep Gaussian processes which can be thought of as a small network of Gaussian processes and which can be employed for flexible regression. The second model class that we study are Gaussian process state-space models. These can be used for time-series modelling, i.e., the task of being given a stream of data ordered by time and then predicting future observations. For both model classes the state-of-the-art approaches offer a trade-off between expressive models and computational properties (e.g. speed or convergence properties) and mostly employ variational inference. Our goal is to improve inference in both models by first getting a deep understanding of the existing methods and then, based on this, to design better inference methods. We achieve this by either exploring the existing trade-offs or by providing general improvements applicable to multiple methods.
We first provide an extensive background, introducing Gaussian processes and their sparse (approximate and efficient) variants. We continue with a description of the models under consideration in this thesis, deep Gaussian processes and Gaussian process state-space models, including detailed derivations and a theoretical comparison of existing methods.
Then we start analysing deep Gaussian processes more closely: Trading off the properties (good optimisation versus expressivity) of state-of-the-art methods in this field, we propose a new variational inference based approach. We then demonstrate experimentally that our new algorithm leads to better calibrated uncertainty estimates than existing methods.
Next, we turn our attention to Gaussian process state-space models, where we closely analyse the theoretical properties of existing methods.The understanding gained in this process leads us to propose a new inference scheme for general Gaussian process state-space models that incorporates effects on multiple time scales. This method is more efficient than previous approaches for long timeseries and outperforms its comparison partners on data sets in which effects on multiple time scales (fast and slowly varying dynamics) are present.
Finally, we propose a new inference approach for Gaussian process state-space models that trades off the properties of state-of-the-art methods in this field. By combining variational inference with another approximate inference method, the Laplace approximation, we design an efficient algorithm that outperforms its comparison partners since it achieves better calibrated uncertainties.
N2  - Bei Vorhersagen auf bisher ungesehenen Datenpunkten liefern die meisten maschinellen Lernmethoden lediglich Punktprognosen. Dies kann problematisch sein, wenn die Daten durch Rauschen verfälscht sind, z. B. durch unvollkommene Messungen, oder wenn der abgefragte Datenpunkt sich stark von den Daten unterscheidet, mit denen das maschinelle Lernmodell trainiert wurde. Mithilfe probabilistischer Modellierung (einem Teilgebiet des maschinellen Lernens) werden die Vorhersagen der Methoden auf natürliche Weise durch Unsicherheiten ergänzt. Dies erlaubt es, Informationen über Messunsicherheiten in den Modellierungsprozess mit einfließen zu lassen, sowie abzuschätzen, bei welchen Vorhersagen dem Modell vertraut werden kann. Grundlage vieler probabilistischer Modelle bilden Gaußprozesse, die gründlich erforscht und äußerst flexibel sind und daher häufig als Bausteine für größere Modelle dienen. Für Regressionsprobleme, was heißt, von einem Datensatz bestehend aus Eingangsgrößen und zugehörigen Messungen auf wahrscheinliche Messwerte für bisher ungesehene Eingangsgrößen zu schließen, sind Gaußprozesse hervorragend geeignet. Zusätzlich können sie an viele weitere Aufgabenstellungen des maschinellen Lernens angepasst werden. Die Bestimmung der optimalen Parameter eines solchen Gaußprozessmodells (in einer annehmbaren Zeit) ist jedoch nur für Regression auf kleinen Datensätzen möglich. In allen anderen Fällen muss auf approximative Inferenzmethoden zurückgegriffen werden, wobei variationelle Inferenz die bekannteste ist.  In dieser Dissertation untersuchen wir Modelle, die Gaußprozesse eingebettet in andere Modelle enthalten, um Letztere flexibler und/oder probabilistisch zu machen. Das erste Beispiel hierbei sind tiefe Gaußprozesse, die man sich als kleines Netzwerk von Gaußprozessen vorstellen kann und die für flexible Regression eingesetzt werden können. Die zweite Modellklasse, die wir genauer analysieren ist die der Gaußprozess-Zustandsraummodelle. Diese können zur Zeitreihenmodellierung verwendet werden, das heißt, um zukünftige Datenpunkte auf Basis eines nach der Zeit geordneten Eingangsdatensatzes vorherzusagen. Für beide genannten Modellklassen bieten die modernsten Ansatze einen Kompromiss zwischen expressiven Modellen und wunschenswerten rechentechnischen Eigenschaften (z. B. Geschwindigkeit oder Konvergenzeigenschaften). Desweiteren wird für die meisten Methoden variationelle Inferenz verwendet. Unser Ziel ist es, die Inferenz für beide Modellklassen zu verbessern, indem wir zunächst ein tieferes Verständnis der bestehenden Ansätze erlangen und darauf aufbauend bessere Inferenzverfahren entwickeln. Indem wir die bestehenden Kompromisse der heutigen Methoden genauer untersuchen, oder dadurch, dass wir generelle Verbesserungen anbieten, die sich auf mehrere Modelle anwenden lassen, erreichen wir dieses Ziel.  Wir beginnen die Thesis mit einer umfassender Einführung, die den notwendigen technischen Hintergrund zu Gaußprozessen sowie spärlichen (approximativen und effizienten) Gaußprozessen enthält. Anschließend werden die in dieser Thesis behandelten Modellklassen, tiefe Gaußprozesse und Gaußprozess-Zustandsraummodelle, eingeführt, einschließlich detaillierter Herleitungen und eines theoretischen Vergleichs existierender Methoden.  Darauf aufbauend untersuchen wir zuerst tiefe Gaußprozesse genauer und entwickeln dann eine neue Inferenzmethode. Diese basiert darauf, die wünschenswerten Eigenschaften (gute Optimierungseigenschaften gegenüber Expressivität) der modernsten Ansätze gegeneinander abzuwägen. Anschließend zeigen wir experimentell, dass unser neuer Algorithmus zu besser kalibrierten Unsicherheitsabschätzungen als bei bestehenden Methoden führt.  Als Nächstes wenden wir uns Gaußprozess-Zustandsraummodelle zu, wo wir zuerst die theoretischen Eigenschaften existierender Ansätze genau analysieren. Wir nutzen das dabei gewonnene Verständnis, um ein neues Inferenzverfahren für Gaußprozess-Zustandsraummodelle einzuführen, welches Effekte auf verschiedenen Zeitskalen berücksichtigt. Für lange Zeitreihen ist diese Methode effizienter als bisherige Ansätze. Darüber hinaus übertrifft sie ihre Vergleichspartner auf Datensätzen, bei denen Effekte auf mehreren Zeitskalen (sich schnell und langsam verändernde Signale) auftreten.  Zuletzt schlagen wir ein weiteres neues Inferenzverfahren für Gaußprozess-Zustandsraummodelle vor, das die Eigenschaften der aktuellsten Methoden auf diesem Gebiet gegeneinander abwägt. Indem wir variationelle Inferenz mit einem weiteren approximativen Inferenzverfahren, der Laplace- Approximation, kombinieren, entwerfen wir einen effizienten Algorithmus der seine Vergleichspartner dadurch übertrifft, dass er besser kalibrierte Unsicherheitsvorhersagen erzielt.
KW  - probabilistic machine learning
KW  - Gaussian processes
KW  - variational inference
KW  - deep Gaussian processes
KW  - Gaussian process state-space models
KW  - Gauß-Prozess Zustandsraummodelle
KW  - Gauß-Prozesse
KW  - tiefe Gauß-Prozesse
KW  - probabilistisches maschinelles Lernen
KW  - variationelle Inferenz
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-604441
ER  - 
TY  - JOUR
A1  - Stettner, Samuel
A1  - Lantuit, Hugues
A1  - Heim, Birgit
A1  - Eppler, Jayson
A1  - Roth, Achim
A1  - Bartsch, Annett
A1  - Rabus, Bernhard
T1  - TerraSAR-X time series fill a gap in spaceborne snowmelt monitoring of small arctic catchments
BT  - a case study on qikiqtaruk (Herschel Island), Canada
JF  - Remote sensing
N2  - The timing of snowmelt is an important turning point in the seasonal cycle of small Arctic catchments. The TerraSAR-X (TSX) satellite mission is a synthetic aperture radar system (SAR) with high potential to measure the high spatiotemporal variability of snow cover extent (SCE) and fractional snow cover (FSC) on the small catchment scale. We investigate the performance of multi-polarized and multi-pass TSX X-Band SAR data in monitoring SCE and FSC in small Arctic tundra catchments of Qikiqtaruk (Herschel Island) off the Yukon Coast in the Western Canadian Arctic. We applied a threshold based segmentation on ratio images between TSX images with wet snow and a dry snow reference, and tested the performance of two different thresholds. We quantitatively compared TSX- and Landsat 8-derived SCE maps using confusion matrices and analyzed the spatiotemporal dynamics of snowmelt from 2015 to 2017 using TSX, Landsat 8 and in situ time lapse data. Our data showed that the quality of SCE maps from TSX X-Band data is strongly influenced by polarization and to a lesser degree by incidence angle. VH polarized TSX data performed best in deriving SCE when compared to Landsat 8. TSX derived SCE maps from VH polarization detected late lying snow patches that were not detected by Landsat 8. Results of a local assessment of TSX FSC against the in situ data showed that TSX FSC accurately captured the temporal dynamics of different snow melt regimes that were related to topographic characteristics of the studied catchments. Both in situ and TSX FSC showed a longer snowmelt period in a catchment with higher contributions of steep valleys and a shorter snowmelt period in a catchment with higher contributions of upland terrain. Landsat 8 had fundamental data gaps during the snowmelt period in all 3 years due to cloud cover. The results also revealed that by choosing a positive threshold of 1 dB, detection of ice layers due to diurnal temperature variations resulted in a more accurate estimation of snow cover than a negative threshold that detects wet snow alone. We find that TSX X-Band data in VH polarization performs at a comparable quality to Landsat 8 in deriving SCE maps when a positive threshold is used. We conclude that TSX data polarization can be used to accurately monitor snowmelt events at high temporal and spatial resolution, overcoming limitations of Landsat 8, which due to cloud related data gaps generally only indicated the onset and end of snowmelt.
KW  - Snow Cover Extent (SCE)
KW  - TerraSAR-X
KW  - Landsat
KW  - wet snow
KW  - small Arctic catchments
KW  - satellite time series
Y1  - 2018
U6  - https://doi.org/10.3390/rs10071155
SN  - 2072-4292
VL  - 10
IS  - 7
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Mazurek-Budzyńska, Magdalena
A1  - Behl, Marc
A1  - Neumann, Richard
A1  - Lendlein, Andreas
T1  - 4D-actuators by 3D-printing combined with water-based curing
JF  - Materials today. Communications
N2  - The shape and the actuation capability of state of the art robotic devices typically relies on multimaterial systems from a combination of geometry determining materials and actuation components. Here, we present multifunctional 4D-actuators processable by 3D-printing, in which the actuator functionality is integrated into the shaped body. The materials are based on crosslinked poly(carbonate-urea-urethane) networks (PCUU), synthesized in an integrated process, applying reactive extrusion and subsequent water-based curing. Actuation capability could be added to the PCUU, prepared from aliphatic oligocarbonate diol, isophorone diisocyanate (IPDI) and water, in a thermomechanical programming process. When programmed with a strain of epsilon(prog) = 1400% the PCUU networks exhibited actuation apparent by reversible elongation epsilon'(rev) of up to 22%. In a gripper a reversible bending epsilon'(rev)((be)(nd)()) in the range of 37-60% was achieved when the actuation temperature (T-high) was varied between 45 degrees C and 49 degrees C. The integration of actuation and shape formation could be impressively demonstrated in two PCUU-based reversible fastening systems, which were able to hold weights of up to 1.1 kg. In this way, the multifunctional materials are interesting candidate materials for robotic applications where a freedom in shape design and actuation is required as well as for sustainable fastening systems.
KW  - 4D-actuation
KW  - 3D-printing
KW  - Ink
KW  - Gripper
KW  - Fastener
Y1  - 2022
U6  - https://doi.org/10.1016/j.mtcomm.2021.102966
SN  - 2352-4928
VL  - 30
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Korzeniowska, Karolina
A1  - Korup, Oliver
T1  - Object-based detection of lakes prone to seasonal ice cover on the Tibetan Plateau
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - The Tibetan Plateau, the world's largest orogenic plateau, hosts thousands of lakes that play prominent roles as water resources, environmental archives, and sources of natural hazards such as glacier lake outburst floods. Previous studies have reported that the size of lakes on the Tibetan Plateau has changed rapidly in recent years, possibly because of atmospheric warming. Tracking these changes systematically with remote sensing data is challenging given the different spectral signatures of water, the potential for confusing lakes with glaciers, and difficulties in classifying frozen or partly frozen lakes. Object-based image analysis (OBIA) offers new opportunities for automated classification in this context, and we have explored this method for mapping lakes from LANDSAT images and Shuttle Radar Topography Mission (SRTM) elevation data. We tested our algorithm for most of the Tibetan Plateau, where lakes in tectonic depressions or blocked by glaciers and sediments have different surface colours and seasonal ice cover in images obtained in 1995 and 2015. We combined a modified normalised difference water index (MNDWI) with OBIA and local topographic slope data in order to classify lakes with an area > 10 km(2). Our method derived 323 water bodies, with a total area of 31,258 km(2), or 2.6% of the study area (in 2015). The same number of lakes had covered only 24,892 km(2) in 1995; lake area has increased by -26% in the past two decades. The classification had estimated producer's and user's accuracies of 0.98, with a Cohen's kappa and F-score of 0.98, and may thus be a useful approximation for quantifying regional hydrological budgets. We have shown that our method is flexible and transferable to detecting lakes in diverse physical settings on several continents with similar success rates.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1037 
KW  - Tibetan Plateau
KW  - lakes
KW  - LANDSAT
KW  - SRTM
KW  - MNDWI
KW  - OBIA
KW  - change detection
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-475037
SN  - 1866-8372
IS  - 1037
ER  - 
TY  - JOUR
A1  - Andree, Kerstin
A1  - Ihde, Sven
A1  - Weske, Mathias
A1  - Pufahl, Luise
T1  - An exception handling framework for case management
JF  - Software and Systems Modeling
N2  - In order to achieve their business goals, organizations heavily rely on the operational excellence of their business processes. In traditional scenarios, business processes are usually well-structured, clearly specifying when and how certain tasks have to be executed. Flexible and knowledge-intensive processes are gathering momentum, where a knowledge worker drives the execution of a process case and determines the exact process path at runtime. In the case of an exception, the knowledge worker decides on an appropriate handling. While there is initial work on exception handling in well-structured business processes, exceptions in case management have not been sufficiently researched. This paper proposes an exception handling framework for stage-oriented case management languages, namely Guard Stage Milestone Model, Case Management Model and Notation, and Fragment-based Case Management. The effectiveness of the framework is evaluated with two real-world use cases showing that it covers all relevant exceptions and proposed handling strategies.
KW  - Exception handling
KW  - Knowledge-intensive processes
KW  - Flexible processes;
KW  - Case management
Y1  - 2022
U6  - https://doi.org/10.1007/s10270-022-00993-3
SN  - 1619-1366
SN  - 1619-1374
VL  - 21
IS  - 3
SP  - 939
EP  - 962
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - THES
A1  - Thiede, Tobias
T1  - A multiscale analysis of additively manufactured lattice structures
T1  - Multiskalige Analyse von Additiv Gefertigten Gitterstrukturen
N2  - Additive Manufacturing (AM) in terms of laser powder-bed fusion (L-PBF) offers new prospects regarding the design of parts and enables therefore the production of lattice structures. These lattice structures shall be implemented in various industrial applications (e.g. gas turbines) for reasons of material savings or cooling channels. However, internal defects, residual stress, and structural deviations from the nominal geometry are unavoidable.
In this work, the structural integrity of lattice structures manufactured by means of L-PBF was non-destructively investigated on a multiscale approach.
A workflow for quantitative 3D powder analysis in terms of particle size, particle shape, particle porosity, inter-particle distance and packing density was established. Synchrotron computed tomography (CT) was used to correlate the packing density with the particle size and particle shape. It was also observed that at least about 50% of the powder porosity was released during production of the struts.
Struts are the component of lattice structures and were investigated by means of laboratory CT. The focus was on the influence of the build angle on part porosity and surface quality. The surface topography analysis was advanced by the quantitative characterisation of re-entrant surface features. This characterisation was compared with conventional surface parameters showing their complementary information, but also the need for AM specific surface parameters.
The mechanical behaviour of the lattice structure was investigated with in-situ CT under compression and successive digital volume correlation (DVC). The deformation was found to be knot-dominated, and therefore the lattice folds unit cell layer wise.
The residual stress was determined experimentally for the first time in such lattice structures. Neutron diffraction was used for the non-destructive 3D stress investigation. The principal stress directions and values were determined in dependence of the number of measured directions. While a significant uni-axial stress state was found in the strut, a more hydrostatic stress state was found in the knot. In both cases, strut and knot, seven directions were at least needed to find reliable principal stress directions.
N2  - Das Laserstrahlschmelzen (L-PBF) als Prozess im Bereich der Additiven Fertigung (AM) ermöglicht ein neuartiges Bauteildesign und somit auch die Produktion von komplexen Gitterstrukturen, welche Materialeinsparungen und effizientere Kühlsysteme erlauben und daher für verschiedene industrielle Anwendungen (z.B. Gasturbinen) geeignet sind. Interne Defekte, Eigenspannungen und geometrische Abweichungen von der Soll-Geometrie sind jedoch unvermeidbar.
Im Rahmen dieser Arbeit wird die strukturelle Integrität von L-PBF gefertigten Gitterstrukturen zerstörungsfrei auf verschiedenen Größenskalen untersucht.
Eine Auswerteroutine für dreidimensionale quantitative Pulvercharakterisierung hinsichtlich der Partikelgröße, der -form, der -porosität, des Interpartikelabstands und der Packungsdichte wurde entwickelt. Synchrotron Computertomographie (CT) wurde für die Korrelation der Packungsdichte mit der Partikelgröße und -form genutzt. Darüber hinaus konnte festgestellt werden, dass mindestens 50% der Porosität aus den Pulverpartikel während der Herstellung der Streben mittels L-PBF gelöst wurde.
Streben sind die Grundbausteine der Gitterstrukturen und wurden mit industrieller CT untersucht. Dabei lag der Fokus auf dem Einfluss des Bauwinkels auf die Strebenporosität und -oberflächenqualität. Die Analyse der Oberflächentopographie wurde hinsichtlich einer quantitativen Analyse von sogenannten re-entrant features erweitert. Der Vergleich dieser Auswertung mit konventionellen Oberflächenparametern
offenbarte sowohl deren Komplementarität also auch den Bedarf an neuen AM-spezifischen Oberflächenparametern. In-situ CT Versuche mit anschließender digitaler Volumenkorrelation (DVC) erlaubte die Gitterstruktur bezüglich des mechanischen Verhaltens unter Druckspannung zu bewerten. Aufgrund einer schichtweisen Faltung der Einheitszellen konnte dabei das Versagensverhalten als knoten-dominiert identifiziert werden.
Mittels Neutronenbeugung konnten Eigenspannungen in solchen Gitterstrukturen erstmalig experimentell bestimmt werden. Dabei wurden sowohl die Hauptspannungsrichtungen als auch die -beträge in Abhängigkeit von der Anzahl der gemessenen Spannungsrichtungen bestimmt. Während in der Strebe ein signifikanter uni-axialer Spannungszustand nachgewiesen wurde, zeigte der Knotenpunkt einen hydrostatischeren Spannungszustand. Sowohl im Falle der Strebe als auch des Knotenpunkts waren mindestens sieben gemessene Spannungsrichtungen nötig, um die Hauptspannungsrichtungen verlässlich zu ermitteln.
KW  - additive manufacturing
KW  - laser powder bed fusion
KW  - computed tomography
KW  - neutron diffraction
KW  - in-situ testing
KW  - residual stress
KW  - roughness
KW  - powder particle analysis
KW  - additive Fertigung
KW  - Laserstrahlschmelzen
KW  - Computertomographie
KW  - Neutronendiffraktion
KW  - In-situ Experimente
KW  - Eigenspannung
KW  - Rauheit
KW  - Pulverpartikelanalyse
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-470418
ER  - 
TY  - GEN
A1  - Sahlmann, Kristina
A1  - Clemens, Vera
A1  - Nowak, Michael
A1  - Schnor, Bettina
T1  - MUP
BT  - Simplifying Secure Over-The-Air Update with MQTT for Constrained IoT Devices
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Message Queuing Telemetry Transport (MQTT) is one of the dominating protocols for edge- and cloud-based Internet of Things (IoT) solutions. When a security vulnerability of an IoT device is known, it has to be fixed as soon as possible. This requires a firmware update procedure. In this paper, we propose a secure update protocol for MQTT-connected devices which ensures the freshness of the firmware, authenticates the new firmware and considers constrained devices. We show that the update protocol is easy to integrate in an MQTT-based IoT network using a semantic approach. The feasibility of our approach is demonstrated by a detailed performance analysis of our prototype implementation on a IoT device with 32 kB RAM. Thereby, we identify design issues in MQTT 5 which can help to improve the support of constrained devices.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1094 
KW  - Internet of Things
KW  - security
KW  - firmware update
KW  - MQTT
KW  - edge computing
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-489013
SN  - 1866-8372
IS  - 1094
ER  - 
TY  - JOUR
A1  - Sahlmann, Kristina
A1  - Clemens, Vera
A1  - Nowak, Michael
A1  - Schnor, Bettina
T1  - MUP
BT  - Simplifying Secure Over-The-Air Update with MQTT for Constrained IoT Devices
JF  - Sensors
N2  - Message Queuing Telemetry Transport (MQTT) is one of the dominating protocols for edge- and cloud-based Internet of Things (IoT) solutions. When a security vulnerability of an IoT device is known, it has to be fixed as soon as possible. This requires a firmware update procedure. In this paper, we propose a secure update protocol for MQTT-connected devices which ensures the freshness of the firmware, authenticates the new firmware and considers constrained devices. We show that the update protocol is easy to integrate in an MQTT-based IoT network using a semantic approach. The feasibility of our approach is demonstrated by a detailed performance analysis of our prototype implementation on a IoT device with 32 kB RAM. Thereby, we identify design issues in MQTT 5 which can help to improve the support of constrained devices.
KW  - Internet of Things
KW  - security
KW  - firmware update
KW  - MQTT
KW  - edge computing
Y1  - 2020
U6  - https://doi.org/10.3390/s21010010
SN  - 1424-8220
VL  - 21
IS  - 1
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Oosthoek, Kris
A1  - Dörr, Christian
T1  - Cyber security threats to bitcoin exchanges
BT  - adversary exploitation and laundering techniques
JF  - IEEE transactions on network and service management : a publication of the IEEE
N2  - Bitcoin is gaining traction as an alternative store of value. Its market capitalization transcends all other cryptocurrencies in the market. But its high monetary value also makes it an attractive target to cyber criminal actors. Hacking campaigns usually target an ecosystem's weakest points. In Bitcoin, the exchange platforms are one of them. Each exchange breach is a threat not only to direct victims, but to the credibility of Bitcoin's entire ecosystem. Based on an extensive analysis of 36 breaches of Bitcoin exchanges, we show the attack patterns used to exploit Bitcoin exchange platforms using an industry standard for reporting intelligence on cyber security breaches. Based on this we are able to provide an overview of the most common attack vectors, showing that all except three hacks were possible due to relatively lax security. We show that while the security regimen of Bitcoin exchanges is subpar compared to other financial service providers, the use of stolen credentials, which does not require any hacking, is decreasing. We also show that the amount of BTC taken during a breach is decreasing, as well as the exchanges that terminate after being breached. Furthermore we show that overall security posture has improved, but still has major flaws. To discover adversarial methods post-breach, we have analyzed two cases of BTC laundering. Through this analysis we provide insight into how exchange platforms with lax cyber security even further increase the intermediary risk introduced by them into the Bitcoin ecosystem.
KW  - Bitcoin
KW  - Computer crime
KW  - Cryptography
KW  - Ecosystems
KW  - Currencies
KW  - Industries
KW  - Vocabulary
KW  - cryptocurrency exchanges
KW  - cyber
KW  - security
KW  - cyber threat intelligence
KW  - attacks
KW  - vulnerabilities
KW  - forensics
Y1  - 2021
U6  - https://doi.org/10.1109/TNSM.2020.3046145
SN  - 1932-4537
VL  - 18
IS  - 2
SP  - 1616
EP  - 1628
PB  - IEEE
CY  - New York
ER  - 
TY  - GEN
A1  - Mielke, Christian
A1  - Rogass, Christian
A1  - Boesche, Nina
A1  - Segl, Karl
A1  - Altenberger, Uwe
T1  - EnGeoMAP 2.0
BT  - automated hyperspectral mineral identification for the German EnMAP space mission
N2  - Algorithms for a rapid analysis of hyperspectral data are becoming more and more important with planned next generation spaceborne hyperspectral missions such as the Environmental Mapping and Analysis Program (EnMAP) and the Japanese Hyperspectral Imager Suite (HISUI), together with an ever growing pool of hyperspectral airborne data. The here presented EnGeoMAP 2.0 algorithm is an automated system for material characterization from imaging spectroscopy data, which builds on the theoretical framework of the Tetracorder and MICA (Material Identification and Characterization Algorithm) of the United States Geological Survey and of EnGeoMAP 1.0 from 2013. EnGeoMAP 2.0 includes automated absorption feature extraction, spatio-spectral gradient calculation and mineral anomaly detection. The usage of EnGeoMAP 2.0 is demonstrated at the mineral deposit sites of Rodalquilar (SE-Spain) and Haib River (S-Namibia) using HyMAP and simulated EnMAP data. Results from Hyperion data are presented as supplementary information.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 365 
KW  - EnMAP
KW  - Hyperion
KW  - EnGeoMAP 2.0
KW  - mineral mapping
KW  - imaging spectroscopy
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-400650
ER  - 
TY  - GEN
A1  - Bösche, Nina Kristine
A1  - Rogass, Christian
A1  - Lubitz, Christin
A1  - Brell, Maximilian
A1  - Herrmann, Sabrina
A1  - Mielke, Christian
A1  - Tonn, Sabine
A1  - Appelt, Oona
A1  - Altenberger, Uwe
A1  - Kaufmann, Hermann
T1  - Hyperspectral REE (Rare Earth Element) mapping of outcrops
BT  - applications for neodymium detection
N2  - In this study, an in situ application for identifying neodymium (Nd) enriched surface materials that uses multitemporal hyperspectral images is presented (HySpex sensor). Because of the narrow shape and shallow absorption depth of the neodymium absorption feature, a method was developed for enhancing and extracting the necessary information for neodymium from image spectra, even under illumination conditions that are not optimal. For this purpose, the two following approaches were developed: (1) reducing noise and analyzing changing illumination conditions by averaging multitemporal image scenes and (2) enhancing the depth of the desired absorption band by deconvolving every image spectrum with a Gaussian curve while the rest of the spectrum remains unchanged (Richardson-Lucy deconvolution). To evaluate these findings, nine field samples from the Fen complex in Norway were analyzed using handheld X-ray fluorescence devices and by conducting detailed laboratory-based geochemical rare earth element determinations. The result is a qualitative outcrop map that highlights zones that are enriched in neodymium. To reduce the influences of non-optimal illumination, particularly at the studied site, a minimum of seven single acquisitions is required. Sharpening the neodymium absorption band allows for robust mapping, even at the outer zones of enrichment. From the geochemical investigations, we found that iron oxides decrease the applicability of the method. However, iron-related absorption bands can be used as secondary indicators for sulfidic ore zones that are mainly enriched with rare earth elements. In summary, we found that hyperspectral spectroscopy is a noninvasive, fast and cost-saving method for determining neodymium at outcrop surfaces
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 350 
KW  - rare earth elements
KW  - imaging spectroscopy
KW  - neodymium
KW  - hyperspectral
KW  - HySpex
KW  - remote sensing
KW  - Fen complex
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-400171
ER  - 
TY  - GEN
A1  - Arodudu, Oludunsin Tunrayo
A1  - Helming, Katharina
A1  - Wiggering, Hubert
A1  - Voinov, Alexey
T1  - Bioenergy from low-intensity agricultural systems
BT  - an energy efficiency analysis
N2  - In light of possible future restrictions on the use of fossil fuel, due to climate change obligations and continuous depletion of global fossil fuel reserves, the search for alternative renewable energy sources is expected to be an issue of great concern for policy stakeholders. This study assessed the feasibility of bioenergy production under relatively low-intensity conservative, eco-agricultural settings (as opposed to those produced under high-intensity, fossil fuel based industrialized agriculture). Estimates of the net energy gain (NEG) and the energy return on energy invested (EROEI) obtained from a life cycle inventory of the energy inputs and outputs involved reveal that the energy efficiency of bioenergy produced in low-intensity eco-agricultural systems could be as much as much as 448.5–488.3 GJ·ha−1 of NEG and an EROEI of 5.4–5.9 for maize ethanol production systems, and as much as 155.0–283.9 GJ·ha−1 of NEG and an EROEI of 14.7–22.4 for maize biogas production systems. This is substantially higher than for industrialized agriculture with a NEG of 2.8–52.5 GJ·ha−1 and an EROEI of 1.2–1.7 for maize ethanol production systems, as well as a NEG of 59.3–188.7 GJ·ha−1 and an EROEI of 2.2–10.2 for maize biogas production systems. Bioenergy produced in low-intensity eco-agricultural systems could therefore be an important source of energy with immense net benefits for local and regional end-users, provided a more efficient use of the co-products is ensured.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 351 
KW  - bioenergy
KW  - biofuel
KW  - energy efficiency
KW  - NEG
KW  - EROEI
KW  - high-intensity industrialized agricultural production systems
KW  - low-intensity eco-agricultural production systems
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-400403
ER  - 
TY  - GEN
A1  - Chen, Jie
A1  - Günther, Frank
A1  - Grosse, Guido
A1  - Liu, Lin
A1  - Lin, Hui
T1  - Sentinel-1 InSAR Measurements of Elevation Changes over Yedoma Uplands on Sobo-Sise Island, Lena Delta
T2  - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe
N2  - Yedoma-extremely ice-rich permafrost with massive ice wedges formed during the Late Pleistocene-is vulnerable to thawing and degradation under climate warming. Thawing of ice-rich Yedoma results in lowering of surface elevations. Quantitative knowledge about surface elevation changes helps us to understand the freeze-thaw processes of the active layer and the potential degradation of Yedoma deposits. In this study, we use C-band Sentinel-1 InSAR measurements to map the elevation changes over ice-rich Yedoma uplands on Sobo-Sise Island, Lena Delta with frequent revisit observations (as short as six or 12 days). We observe significant seasonal thaw subsidence during summer months and heterogeneous inter-annual elevation changes from 2016-17. We also observe interesting patterns of stronger seasonal thaw subsidence on elevated flat Yedoma uplands by comparing to the surrounding Yedoma slopes. Inter-annual analyses from 2016-17 suggest that our observed positive surface elevation changes are likely caused by the delayed progression of the thaw season in 2017, associated with mean annual air temperature fluctuations.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 690 
KW  - Sentinel-1 InSAR
KW  - Yedoma uplands
KW  - Sobo-Sise Island
KW  - summer heave
KW  - permafrost thaw subsidence
KW  - active layer
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-426807
SN  - 1866-8372
IS  - 690
ER  - 
TY  - JOUR
A1  - Runge, Alexandra
A1  - Grosse, Guido
T1  - Comparing Spectral Characteristics of Landsat-8 and Sentinel-2 Same-Day Data for Arctic-Boreal Regions
JF  - Remote Sensing
N2  - The Arctic-Boreal regions experience strong changes of air temperature and precipitation regimes, which affect the thermal state of the permafrost. This results in widespread permafrost-thaw disturbances, some unfolding slowly and over long periods, others occurring rapidly and abruptly. Despite optical remote sensing offering a variety of techniques to assess and monitor landscape changes, a persistent cloud cover decreases the amount of usable images considerably. However, combining data from multiple platforms promises to increase the number of images drastically. We therefore assess the comparability of Landsat-8 and Sentinel-2 imagery and the possibility to use both Landsat and Sentinel-2 images together in time series analyses, achieving a temporally-dense data coverage in Arctic-Boreal regions. We determined overlapping same-day acquisitions of Landsat-8 and Sentinel-2 images for three representative study sites in Eastern Siberia. We then compared the Landsat-8 and Sentinel-2 pixel-pairs, downscaled to 60 m, of corresponding bands and derived the ordinary least squares regression for every band combination. The acquired coefficients were used for spectral bandpass adjustment between the two sensors. The spectral band comparisons showed an overall good fit between Landsat-8 and Sentinel-2 images already. The ordinary least squares regression analyses underline the generally good spectral fit with intercept values between 0.0031 and 0.056 and slope values between 0.531 and 0.877. A spectral comparison after spectral bandpass adjustment of Sentinel-2 values to Landsat-8 shows a nearly perfect alignment between the same-day images. The spectral band adjustment succeeds in adjusting Sentinel-2 spectral values to Landsat-8 very well in Eastern Siberian Arctic-Boreal landscapes. After spectral adjustment, Landsat and Sentinel-2 data can be used to create temporally-dense time series and be applied to assess permafrost landscape changes in Eastern Siberia. Remaining differences between the sensors can be attributed to several factors including heterogeneous terrain, poor cloud and cloud shadow masking, and mixed pixels.
KW  - spectral adjustment
KW  - northern high latitudes
KW  - permafrost
KW  - time series
KW  - optical data
KW  - surface reflectance
KW  - correlation
KW  - permafrost disturbances
KW  - land cover change
Y1  - 2019
U6  - https://doi.org/10.3390/rs11141730
SN  - 2072-4292
VL  - 11
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Eerqing, Narima
A1  - Subramanian, Sivaraman
A1  - Rubio Jimenez, Jesus
A1  - Lutz, Tobias
A1  - Wu, Hsin-Yu
A1  - Anders, Janet
A1  - Soeller, Christian
A1  - Vollmer, Frank
T1  - Comparing transient oligonucleotide hybridization kinetics using DNA-PAINT and optoplasmonic single-molecule sensing on gold nanorods
JF  - ACS photonics / American Chemical Society
N2  - We report a comparison of two photonic techniques for single-molecule sensing: fluorescence nanoscopy and optoplasmonic sensing. As the test system, oligonucleotides with and without fluorescent labels are transiently hybridized to complementary "docking" strands attached to gold nanorods. Comparing the measured single-molecule kinetics helps to examine the influence of the fluorescent labels as well as factors arising from different sensing geometries. Our results demonstrate that DNA dissociation is not significantly altered by the fluorescent labels and that DNA association is affected by geometric factors in the two techniques. These findings open the door to exploiting plasmonic sensing and fluorescence nanoscopy in a complementary fashion, which will aid in building more powerful sensors and uncovering the intricate effects that influence the behavior of single molecules.
KW  - single-molecule
KW  - plasmonics
KW  - whispering gallery modes
KW  - optoplasmonic
KW  - DNA-PAINT
KW  - fluorescence
KW  - localization microscopy
Y1  - 2021
U6  - https://doi.org/10.1021/acsphotonics.1c01179
SN  - 2330-4022
VL  - 8
IS  - 10
SP  - 2882
EP  - 2888
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Izgi, Gizem
A1  - Eibl, Eva P. S.
A1  - Donner, Stefanie
A1  - Bernauer, Felix
T1  - Performance test of the rotational sensor blueSeis-3A in a huddle test in Fürstenfeldbruck
JF  - Sensors
N2  - Rotational motions play a key role in measuring seismic wavefield properties. Using newly developed portable rotational instruments, it is now possible to directly measure rotational motions in a broad frequency range. Here, we investigated the instrumental self-noise and data quality in a huddle test in Fürstenfeldbruck, Germany, in August 2019. We compare the data from six rotational and three translational sensors. We studied the recorded signals using correlation, coherence analysis, and probabilistic power spectral densities. We sorted the coherent noise into five groups with respect to the similarities in frequency content and shape of the signals. These coherent noises were most likely caused by electrical devices, the dehumidifier system in the building, humans, and natural sources such as wind. We calculated self-noise levels through probabilistic power spectral densities and by applying the Sleeman method, a three-sensor method. Our results from both methods indicate that self-noise levels are stable between 0.5 and 40 Hz. Furthermore, we recorded the 29 August 2019 ML 3.4 Dettingen earthquake. The calculated source directions are found to be realistic for all sensors in comparison to the real back azimuth. We conclude that the five tested blueSeis-3A rotational sensors, when compared with respect to coherent noise, self-noise, and source direction, provide reliable and consistent results. Hence, field experiments with single rotational sensors can be undertaken.
KW  - rotational seismology
KW  - huddle test
KW  - coherency
KW  - source direction
KW  - coherent noise
KW  - blueSeis-3A sensors
Y1  - 2021
U6  - https://doi.org/10.3390/s21093170
SN  - 1424-8220
VL  - 21
IS  - 9
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Höhne, Stefan
A1  - Tiberius, Victor
T1  - Powered by blockchain
BT  - forecasting blockchain use in the electricity market
JF  - International journal of energy sector management
N2  - Purpose: The purpose of this study is to formulate the most probable future scenario for the use of blockchain technology within the next 5–10 years in the electricity sector based on today’s experts’ views.
Design/methodology/approach: An international, two-stage Delphi study with 20 projections is used. 
Findings: According to the experts, blockchain applications will be primarily based on permissioned or consortium blockchains. Blockchain-based applications will integrate Internet of Things devices in the power grid, manage the e-mobility infrastructure, automate billing and direct payment and issue certificates regarding the origin of electricity. Blockchain solutions are expected to play an important big role in fostering peer-to-peer trading in microgrids, further democratizing and decentralizing the energy sector. New regulatory frameworks become necessary.
Research limitations/implications: The Delphi study’s scope is rather broad than narrow and detailed. Further studies should focus on partial scenarios. 
Practical implications: Electricity market participants should build blockchain-based competences and collaborate in current pilot projects. 
Social implications: Blockchain technology will further decentralize the energy sector and probably reduce transaction costs. Originality/value: Despite the assumed importance of blockchain technology, no coherent foresight study on its use and implications exists yet. This study closes this research gap.
KW  - innovation
KW  - surveys
KW  - scenario analysis
KW  - blockchain technology
KW  - Delphi
KW  - method
KW  - digitization
KW  - electricity market
Y1  - 2020
U6  - https://doi.org/10.1108/IJESM-10-2019-0002
SN  - 1750-6220
SN  - 1750-6239
VL  - 14
IS  - 6
SP  - 1221
EP  - 1238
PB  - Emerald Group Publishing Limited
CY  - Bingley
ER  - 
TY  - JOUR
A1  - Montrone, Lorenzo
A1  - Steckel, Jan Christoph
A1  - Kalkuhl, Matthias
T1  - The type of power capacity matters for economic development
BT  - evidence from a global panel
JF  - Resource and energy economics
N2  - We examine the relationship between different types of power investments and regional economic dynamics. We construct a novel panel dataset combining data on regional GDP and power capacity additions for different technologies between 1960 and 2015, which covers 65% of the global power capacity that has been installed in this period. We use an event study design to identify the effect of power capacity addition on GDP per capita, exploiting the fact that the exact amount of power capacity coming online each year is determined by random construction delays. We find evidence that GDP per capita increases by 0.2% in the 6 years around the coming online of 100 MW coal-fired power capacity. We find similar effects for hydropower capacity, but not for any other type of power capacity. The positive effects are regionally bounded and stronger for projects on new sites (green-field). The magnitude of this effect might not be comparable to the total external costs of building new coal-fired power capacity, yet our results help to explain why policymakers favor coal investments for spurring regional growth.
KW  - Energy and development
KW  - Economic growth
KW  - Public infrastructure
KW  - Public investments
KW  - Electricity sector
Y1  - 2022
U6  - https://doi.org/10.1016/j.reseneeco.2022.101313
SN  - 0928-7655
VL  - 69
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Atmani, Farid
A1  - Bookhagen, Bodo
A1  - Smith, Taylor
T1  - Measuring Vegetation Heights and Their Seasonal Changes in the Western Namibian Savanna Using Spaceborne Lidars
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - The Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) with its land and vegetation height data product (ATL08), and Global Ecosystem Dynamics Investigation (GEDI) with its terrain elevation and height metrics data product (GEDI Level 2A) missions have great potential to globally map ground and canopy heights. Canopy height is a key factor in estimating above-ground biomass and its seasonal changes; these satellite missions can also improve estimated above-ground carbon stocks. This study presents a novel Sparse Vegetation Detection Algorithm (SVDA) which uses ICESat-2 (ATL03, geolocated photons) data to map tree and vegetation heights in a sparsely vegetated savanna ecosystem. The SVDA consists of three main steps: First, noise photons are filtered using the signal confidence flag from ATL03 data and local point statistics. Second, we classify ground photons based on photon height percentiles. Third, tree and grass photons are classified based on the number of neighbors. We validated tree heights with field measurements (n = 55), finding a root-mean-square error (RMSE) of 1.82 m using SVDA, GEDI Level 2A (Geolocated Elevation and Height Metrics product): 1.33 m, and ATL08: 5.59 m. Our results indicate that the SVDA is effective in identifying canopy photons in savanna ecosystems, where ATL08 performs poorly. We further identify seasonal vegetation height changes with an emphasis on vegetation below 3 m; widespread height changes in this class from two wet-dry cycles show maximum seasonal changes of 1 m, possibly related to seasonal grass-height differences. Our study shows the difficulties of vegetation measurements in savanna ecosystems but provides the first estimates of seasonal biomass changes.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1275 
KW  - ICESat-2
KW  - GEDI
KW  - canopy height
KW  - lidar
KW  - savanna
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-569915
SN  - 1866-8372
IS  - 1275
ER  - 
TY  - JOUR
A1  - Atmani, Farid
A1  - Bookhagen, Bodo
A1  - Smith, Taylor
T1  - Measuring vegetation heights and their seasonal changes in the Western Namibian Savanna using spaceborne lidars
JF  - Remote sensing / Molecular Diversity Preservation International (MDPI)
N2  - The Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) with its land and vegetation height data product (ATL08), and Global Ecosystem Dynamics Investigation (GEDI) with its terrain elevation and height metrics data product (GEDI Level 2A) missions have great potential to globally map ground and canopy heights. Canopy height is a key factor in estimating above-ground biomass and its seasonal changes; these satellite missions can also improve estimated above-ground carbon stocks. This study presents a novel Sparse Vegetation Detection Algorithm (SVDA) which uses ICESat-2 (ATL03, geolocated photons) data to map tree and vegetation heights in a sparsely vegetated savanna ecosystem. The SVDA consists of three main steps: First, noise photons are filtered using the signal confidence flag from ATL03 data and local point statistics. Second, we classify ground photons based on photon height percentiles. Third, tree and grass photons are classified based on the number of neighbors. We validated tree heights with field measurements (n = 55), finding a root-mean-square error (RMSE) of 1.82 m using SVDA, GEDI Level 2A (Geolocated Elevation and Height Metrics product): 1.33 m, and ATL08: 5.59 m. Our results indicate that the SVDA is effective in identifying canopy photons in savanna ecosystems, where ATL08 performs poorly. We further identify seasonal vegetation height changes with an emphasis on vegetation below 3 m; widespread height changes in this class from two wet-dry cycles show maximum seasonal changes of 1 m, possibly related to seasonal grass-height differences. Our study shows the difficulties of vegetation measurements in savanna ecosystems but provides the first estimates of seasonal biomass changes.
KW  - ICESat-2
KW  - GEDI
KW  - canopy height
KW  - lidar
KW  - savanna
Y1  - 2022
U6  - https://doi.org/10.3390/rs14122928
SN  - 2072-4292
VL  - 14
IS  - 12
SP  - 1
EP  - 20
PB  - MDPI
CY  - Basel, Schweiz
ET  - 12
ER  - 
TY  - JOUR
A1  - Wang, Xuepu
A1  - Sperling, Marcel
A1  - Reifarth, Martin
A1  - Böker, Alexander
T1  - Shaping metallic nanolattices
BT  - Design by microcontact printing from wrinkled stamps
JF  - Small
N2  - A method for the fabrication of well-defined metallic nanostructures is presented here in a simple and straightforward fashion. As an alternative to lithographic techniques, this routine employs microcontact printing utilizing wrinkled stamps, which are prepared from polydimethylsiloxane (PDMS), and includes the formation of hydrophobic stripe patterns on a substrate via the transfer of oligomeric PDMS. Subsequent backfilling of the interspaces between these stripes with a hydroxyl-functional poly(2-vinyl pyridine) then provides the basic pattern for the deposition of citrate-stabilized gold nanoparticles promoted by electrostatic interaction. The resulting metallic nanostripes can be further customized by peeling off particles in a second microcontact printing step, which employs poly(ethylene imine) surface-decorated wrinkled stamps, to form nanolattices. Due to the independent adjustability of the period dimensions of the wrinkled stamps and stamp orientation with respect to the substrate, particle arrays on the (sub)micro-scale with various kinds of geometries are accessible in a straightforward fashion. This work provides an alternative, cost-effective, and scalable surface-patterning technique to fabricate nanolattice structures applicable to multiple types of functional nanoparticles. Being a top-down method, this process could be readily implemented into, e.g., the fabrication of optical and sensing devices on a large scale.
KW  - gold nanoparticle assembly
KW  - hydroxyl-functional poly(2-vinyl pyridine)
KW  - metallic nanolattices
KW  - microcontact printing
KW  - oligomeric
KW  - polydimethylsiloxane
KW  - polydimethylsiloxane wrinkles
KW  - wrinkled stamps
Y1  - 2020
U6  - https://doi.org/10.1002/smll.201906721
SN  - 1613-6810
SN  - 1613-6829
VL  - 16
IS  - 11
SP  - 1
EP  - 8
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Bouncken, Ricarda B.
A1  - Ratzmann, Martin
A1  - Tiberius, Victor
A1  - Brem, Alexander
T1  - Pioneering strategy in supply chain relationships
BT  - how coercive power and contract completeness influence innovation
JF  - IEEE transactions on engineering management
N2  - Today, firms pursuing a pioneering strategy are often engaged in supply chain relationships to benefit from external resources and to improve their innovation. However, this effort can be impeded by power asymmetries in such relationships and especially by the execution of coercive power by their partner firm. Contracts could potentially reduce this risk of opportunistic behavior. Our survey study on 778 small to medium-sized enterprises in the European packaging and medical equipment industries examines how coercive power of the partner and the contractual arrangement between firms moderate the pioneering strategy's innovation outcomes in the short and long run. Our results confirm the negative effect of coercive power on innovation performance in both the short and long term. However, the compensating effect of rather complete contracts differs temporally. Whereas, contract completeness protects against higher dependence at the beginning of the collaboration, their effect diminishes over time. In contrast, rather incomplete contracts enhance the innovation performance in the long term, possibly complemented with trust.
KW  - alliances
KW  - coercive power
KW  - contracts
KW  - pioneering strategy
KW  - R&D
KW  - supply chain
Y1  - 2020
U6  - https://doi.org/10.1109/TEM.2020.3019965
SN  - 0018-9391
VL  - 69
IS  - 6
SP  - 2826
EP  - 2841
PB  - IEEE
CY  - New York
ER  - 
TY  - THES
A1  - Schröder, Jakob
T1  - Fundamentals of diffraction-based residual stress and texture analysis of laser powder bed fused Inconel 718
T1  - Grundlagen der beugungsbasierten Eigenspannungs- und Texturanalyse von laserstrahlgeschmolzenem Inconel 718
N2  - Additive manufacturing (AM) processes enable the production of metal structures with exceptional design freedom, of which laser powder bed fusion (PBF-LB) is one of the most common. In this process, a laser melts a bed of loose feedstock powder particles layer-by-layer to build a structure with the desired geometry. During fabrication, the repeated melting and rapid, directional solidification create large temperature gradients that generate large thermal stress. This thermal stress can itself lead to cracking or delamination during fabrication. More often, large residual stresses remain in the final part as a footprint of the thermal stress. This residual stress can cause premature distortion or even failure of the part in service. Hence, knowledge of the residual stress field is critical for both process optimization and structural integrity.
Diffraction-based techniques allow the non-destructive characterization of the residual stress fields. However, such methods require a good knowledge of the material of interest, as certain assumptions must be made to accurately determine residual stress. First, the measured lattice plane spacings must be converted to lattice strains with the knowledge of a strain-free material state. Second, the measured lattice strains must be related to the macroscopic stress using Hooke's law, which requires knowledge of the stiffness of the material. Since most crystal structures exhibit anisotropic material behavior, the elastic behavior is specific to each lattice plane of the single crystal. Thus, the use of individual lattice planes in monochromatic diffraction residual stress analysis requires knowledge of the lattice plane-specific elastic properties. In addition, knowledge of the microstructure of the material is required for a reliable assessment of residual stress. 
This work presents a toolbox for reliable diffraction-based residual stress analysis. This is presented for a nickel-based superalloy produced by PBF-LB. First, this work reviews the existing literature in the field of residual stress analysis of laser-based AM using diffraction-based techniques. Second, the elastic and plastic anisotropy of the nickel-based superalloy Inconel 718 produced by PBF-LB is studied using in situ energy dispersive synchrotron X-ray and neutron diffraction techniques. These experiments are complemented by ex situ material characterization techniques. These methods establish the relationship between the microstructure and texture of the material and its elastic and plastic anisotropy. Finally, surface, sub-surface, and bulk residual stress are determined using a texture-based approach. Uncertainties of different methods for obtaining stress-free reference values are discussed.
The tensile behavior in the as-built condition is shown to be controlled by texture and cellular sub-grain structure, while in the heat-treated condition the precipitation of strengthening phases and grain morphology dictate the behavior. In fact, the results of this thesis show that the diffraction elastic constants depend on the underlying microstructure, including texture and grain morphology. For columnar microstructures in both as-built and heat-treated conditions, the diffraction elastic constants are best described by the Reuss iso-stress model. Furthermore, the low accumulation of intergranular strains during deformation demonstrates the robustness of using the 311 reflection for the diffraction-based residual stress analysis with columnar textured microstructures. The differences between texture-based and quasi-isotropic approaches for the residual stress analysis are shown to be insignificant in the observed case. However, the analysis of the sub-surface residual stress distributions show, that different scanning strategies result in a change in the orientation of the residual stress tensor. Furthermore, the location of the critical sub-surface tensile residual stress is related to the surface roughness and the microstructure. Finally, recommendations are given for the diffraction-based determination and evaluation of residual stress in textured additively manufactured alloys.
N2  - Additive Fertigungsverfahren (AM) ermöglichen die Herstellung von Metallstrukturen mit außergewöhnlicher Gestaltungsfreiheit, wobei das pulverbettbasierte Laserstrahlschmelzen (PBF-LB) eines der gängigsten dieser Verfahren darstellt. In diesem Verfahren schmilzt ein Laser ein Pulverbett schichtweise auf, um ein Bauteil mit der gewünschten Geometrie zu erzeugen. Während der Fertigung kommt es aufgrund des wiederholten Aufschmelzens und der schnellen, gerichteten Erstarrung zu hohen Temperaturgradienten, die hohe thermische Spannungen erzeugen. Einerseits können diese thermischen Spannungen während des Fertigungsprozesses zur Rissbildung oder zur Ablösung des Bauteils führen. Häufiger jedoch verbleiben große Eigenspannungen im gefertigten Bauteil als Folge der thermischen Spannungen. Diese Eigenspannungen begünstigen die Verzerrung der Bauteile und können sogar ihr vorzeitiges Versagen im Betrieb verursachen. Daher ist die Kenntnis der Eigenspannungsverteilung im Bauteil sowohl für die Prozessoptimierung als auch die strukturelle Integrität bedeutend.
Beugungsbasierte Verfahren ermöglichen die zerstörungsfreie Bestimmung des Eigenspannungsfeldes. Diese Verfahren erfordern jedoch eine vorhergehende Kenntnis der Materialeigenschaften, da gewisse Annahmen getroffen werden müssen, um die Eigenspannungen genau bestimmen zu können. Zunächst müssen aus den gemessenen Abständen der Gitterebenen Gitterdehnungen berechnet werden, wozu der dehnungsfreie Referenzzustand bekannt sein muss. Weiterhin müssen die Gitterdehnungen über das Hookesche Gesetz, unter Bezugnahme der elastischen Eigenschaften, in Spannungen überführt werden. Da die meisten Kristallstrukturen durch ein anisotropes Verhalten gekennzeichnet sind, ist ihr elastisches Verhalten für jede Gitterebene spezifisch. Deshalb bedarf es bei der Nutzung monochromatischer Strahlung zur beugungsbasierten Eigenspannungsbestimmung der Kenntnis der gitterebenenspezifischen elastischen Eigenschaften. Zusätzlich ist das Wissen über die Mikrostruktur des Materials unabdingbar für eine zuverlässige Bestimmung der Eigenspannungen.
Die vorliegende Arbeit präsentiert eine Reihe von Bedingungen, die für eine zuverlässige beugungsbasierte Eigenspannungsanalyse notwendig sind. Dies wird exemplarisch an einer mittels PBF-LB gefertigten Nickelbasis Superlegierung gezeigt. Einleitend wird ein Überblick der Literatur im Bereich der beugungsbasierten Eigenspannungsanalyse mit Bezug zur additiven Fertigung gegeben. Anschließend wird die elastische und plastische Anisotropie der mittels PBF-LB gefertigten Nickelbasis Superlegierung Inconel 718 durch in situ energiedispersive Synchrotron Röntgen- und Neutronenbeugung charakterisiert. Diese Methoden werden durch ex situ Untersuchungsverfahren ergänzt. So wird die Beziehung zwischen der Mikrostruktur und der Textur zur elastischen und plastischen Anisotropie hergestellt. Abschließend werden die Oberflächen-, oberflächennahen-, sowie Volumeneigenspannungen in einem texturbasierten Ansatz bestimmt. Dabei werden Unsicherheiten verschiedener Methoden zur Bestimmung der spannungsfreien Referenz diskutiert.
Das mechanische Verhalten unter Zugbelastung des as-built Zustandes ist dabei durch die Textur und die zelluläre Substruktur bedingt, während es im wärmebehandelten Zustand vom Ausscheidungszustand und der geänderten Kornmorphologie bestimmt wird. Die Ergebnisse dieser Arbeit zeigen, dass die diffraktionselastischen Konstanten von der zugrundeliegenden Mikrostruktur abhängen. Für die kolumnaren Mikrostrukturen, egal ob im as-built oder wärmebehandeltem Zustand, werden die diffraktionselastischen Konstanten am besten durch die Reuss Annahme homogener Spannung beschrieben. Darüber hinaus zeigt die geringe Akkumulation intergranularer Dehnung des 311 Reflexes seine Robustheit für die beugungsbasierte Eigenspannungsanalyse. Im vorhandenen Fall ist der Unterschied zwischen texturbasierten und quasiisotropen Ansätzen zur Eigenspannungsanalyse unbedeutend. Oberflächennahe Eigenspannungsanalysen zeigen jedoch, dass verschiedene Scanstrategien zu einer Änderung in der Ausrichtung des Eigenspannungstensors führen. Weiterhin zeigt die Lage der kritischen oberflächennahen Zugeigenspannungen eine Abhängigkeit zur Oberflächenrauheit und dem Gefüge. Abschließend werden Empfehlungen zur beugungsbasierten Ermittlung und Bewertung von Eigenspannungen in texturierten additiv gefertigten Legierungen gegeben.
KW  - residual stress
KW  - diffraction
KW  - texture
KW  - mechanical behavior
KW  - in-situ testing
KW  - laser powder bed fusion
KW  - additive manufacturing
KW  - electron backscatter diffraction
KW  - diffraction elastic constants
KW  - Inconel 718
KW  - Inconel 718
KW  - additive Fertigung
KW  - Diffraktion
KW  - diffraktionselastische Konstanten
KW  - Elektronenrückstreubeugung
KW  - In-situ Experimente
KW  - Laserstrahlschmelzen
KW  - mechanisches Verhalten
KW  - Eigenspannung
KW  - Textur
Y1  - 2024
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-621972
ER  - 
TY  - JOUR
A1  - Baum, Katharina
A1  - Abramova, Olga
A1  - Meißner, Stefan
A1  - Krasnova, Hanna
T1  - The effects of targeted political advertising on user privacy concerns and digital product acceptance
BT  - a preference-based approach
JF  - Electronic markets
N2  - Online businesses are increasingly relying on targeted advertisements as a revenue stream, which might lead to privacy concerns and hinder product adoption. Therefore, it is crucial for online companies to understand which types of targeted advertisements consumers will accept. In recent years, users have been increasingly targeted by political advertisements, which has caused adverse reactions in media and society. Nonetheless, few studies experimentally investigate user privacy concerns and their role in acceptance decisions in response to targeted political advertisements. To fill this gap, we explore the magnitude of privacy concerns towards targeted political ads compared to “traditional” targeting in the product context. Surprisingly, we find no notable differences in privacy concerns between these data use purposes. In the next step, user preferences over ad types are elicited with the help of a discrete choice experiment in the mobile app adoption context. Our findings suggest that while targeted political advertising is somewhat less desirable than targeted product advertising, the odds of choosing an app are statistically insignificant between two data use purposes. Together, these results contribute to a better understanding of users’ privacy concerns and preferences in the context of targeted political advertising online.
KW  - online privacy
KW  - targeting
KW  - advertisement
KW  - DCE
Y1  - 2023
U6  - https://doi.org/10.1007/s12525-023-00656-1
SN  - 1019-6781
SN  - 1422-8890
VL  - 33
IS  - 46
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Hagemann, Linus
A1  - Abramova, Olga
T1  - Sentiment, we-talk and engagement on social media
BT  - insights from Twitter data mining on the US presidential elections 2020
JF  - Internet research
N2  - Purpose
Given inconsistent results in prior studies, this paper applies the dual process theory to investigate what social media messages yield audience engagement during a political event. It tests how affective cues (emotional valence, intensity and collective self-representation) and cognitive cues (insight, causation, certainty and discrepancy) contribute to public engagement.

Design/methodology/approach
The authors created a dataset of more than three million tweets during the 2020 United States (US) presidential elections. Affective and cognitive cues were assessed via sentiment analysis. The hypotheses were tested in negative binomial regressions. The authors also scrutinized a subsample of far-famed Twitter users. The final dataset, scraping code, preprocessing and analysis are available in an open repository.

Findings
The authors found the prominence of both affective and cognitive cues. For the overall sample, negativity bias was registered, and the tweet’s emotionality was negatively related to engagement. In contrast, in the sub-sample of tweets from famous users, emotionally charged content produced higher engagement. The role of sentiment decreases when the number of followers grows and ultimately becomes insignificant for Twitter participants with many followers. Collective self-representation (“we-talk”) is consistently associated with more likes, comments and retweets in the overall sample and subsamples.

Originality/value
The authors expand the dominating one-sided perspective to social media message processing focused on the peripheral route and hence affective cues. Leaning on the dual process theory, the authors shed light on the effectiveness of both affective (peripheral route) and cognitive (central route) cues on information appeal and dissemination on Twitter during a political event. The popularity of the tweet’s author moderates these relationships.
KW  - social media
KW  - engagement
KW  - data mining
KW  - big data
Y1  - 2023
U6  - https://doi.org/10.1108/INTR-12-2021-0885
SN  - 1066-2243
VL  - 33
IS  - 6
SP  - 2058
EP  - 2085
PB  - Emeral
CY  - Bingley
ER  - 
TY  - JOUR
A1  - Krupnik, Seweryn
A1  - Wagner, Aleksandra
A1  - Vincent, Olga
A1  - Rudek, Tadeusz J.
A1  - Wade, Robert
A1  - Misik, Matúš
A1  - Akerboom, Sanne
A1  - Foulds, Chris
A1  - Smith Stegen, Karen
A1  - Adem, Çiğdem
A1  - Batel, Susana
A1  - Rabitz, Florian
A1  - Certomà, Chiara
A1  - Chodkowska-Miszczuk, Justyna
A1  - Dokupilová, Dušana
A1  - Leiren, Merethe D.
A1  - Ignatieva, Frolova M.
A1  - Gabaldón-Estevan, Daniel.
A1  - Horta, Ana
A1  - Karnøe, Peter
A1  - Lilliestam, Johan
A1  - Loorbach, Derk A.
A1  - Mühlemeier, Susan
A1  - Némoz, Sophie
A1  - Nilsson, Måns
A1  - Osička, Jan
A1  - Papamikrouli, Louiza
A1  - Pellizioni, Luigi
A1  - Sareen, Siddharth
A1  - Sarrica, Mauro
A1  - Seyfang, Gill
A1  - Sovacool, Benjamin K.
A1  - Telesiene, Audrone
A1  - Zapletalova, Veronika
A1  - von Wirth, Timo
T1  - Beyond technology
BT  - a research agenda for social sciences and humanities research on renewable energy in Europe
JF  - Energy research & social science
N2  - This article enriches the existing literature on the importance and role of the social sciences and humanities (SSH) in renewable energy sources research by providing a novel approach to instigating the future research agenda in this field. Employing a series of in-depth interviews, deliberative focus group workshops and a systematic horizon scanning process, which utilised the expert knowledge of 85 researchers from the field with diverse disciplinary backgrounds and expertise, the paper develops a set of 100 priority questions for future research within SSH scholarship on renewable energy sources. These questions were aggregated into four main directions: (i) deep transformations and connections to the broader economic system (i.e. radical ways of (re)arranging socio-technical, political and economic relations), (ii) cultural and geographical diversity (i.e. contextual cultural, historical, political and socio-economic factors influencing citizen support for energy transitions), (iii) complexifying energy governance (i.e. understanding energy systems from a systems dynamics perspective) and (iv) shifting from instrumental acceptance to value-based objectives (i.e. public support for energy transitions as a normative notion linked to trust-building and citizen engagement). While this agenda is not intended to be—and cannot be—exhaustive or exclusive, we argue that it advances the understanding of SSH research on renewable energy sources and may have important value in the prioritisation of SSH themes needed to enrich dialogues between policymakers, funding institutions and researchers. SSH scholarship should not be treated as instrumental to other research on renewable energy but as intrinsic and of the same hierarchical importance.
KW  - horizon scanning
KW  - research priorities
KW  - funding directions
KW  - EU Horizon Europe
KW  - research-policy interface
Y1  - 2022
U6  - https://doi.org/10.1016/j.erss.2022.102536
SN  - 22146296
VL  - 89
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Kleanthis, Nikos
A1  - Stavrakas, Vassilis
A1  - Ceglarz, Andrzej
A1  - Süsser, Diana
A1  - Schibline, Amanda
A1  - Lilliestam, Johan
A1  - Flamos, Alexandros
T1  - Eliciting knowledge from stakeholders to identify critical issues of the transition to climate neutrality in Greece, the Nordic Region, and the European Union
JF  - Energy research & social ccience
N2  - There are considerable differences in the pace and underlying motivations of the energy transition in the different geographical contexts across Europe. The European Union's commitment to climate neutrality by 2050 requires a better understanding of the energy transition in different contexts and scales to improve cooperation of involved actors. In this article, we identify critical issues and challenges of the European energy transition as perceived by stakeholders and investigate how these perceptions vary across geographical contexts. To do so, we couple a policy document analysis with research based on stakeholder engagement activities in three different scales, national (Greece), regional (Nordic Region) and continental scale (European Union). Our findings show that stakeholder perspectives on the energy transition depend on contextual factors underlying the need for policies sensitive to the different transition issues and challenges in European regions. They also reveal cross-cutting issues and challenges among the three case studies, which could lead to further improvement of the cross-country collaboration to foster the European energy transition.
KW  - challenges
KW  - case studies
KW  - energy policy
KW  - energy transition
KW  - climate neutrality
KW  - stakeholder engagement
Y1  - 2022
U6  - https://doi.org/10.1016/j.erss.2022.102836
SN  - 2214-6296
VL  - 93
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Brandes, Stefanie
A1  - Sicks, Florian
A1  - Berger, Anne
T1  - Behaviour classification on giraffes (Giraffa camelopardalis) using machine learning algorithms on triaxial acceleration data of two commonly used GPS devices and its possible application for their management and conservation
JF  - Sensors
N2  - Averting today's loss of biodiversity and ecosystem services can be achieved through conservation efforts, especially of keystone species. Giraffes (Giraffa camelopardalis) play an important role in sustaining Africa's ecosystems, but are 'vulnerable' according to the IUCN Red List since 2016. Monitoring an animal's behavior in the wild helps to develop and assess their conservation management. One mechanism for remote tracking of wildlife behavior is to attach accelerometers to animals to record their body movement. We tested two different commercially available high-resolution accelerometers, e-obs and Africa Wildlife Tracking (AWT), attached to the top of the heads of three captive giraffes and analyzed the accuracy of automatic behavior classifications, focused on the Random Forests algorithm. For both accelerometers, behaviors of lower variety in head and neck movements could be better predicted (i.e., feeding above eye level, mean prediction accuracy e-obs/AWT: 97.6%/99.7%; drinking: 96.7%/97.0%) than those with a higher variety of body postures (such as standing: 90.7-91.0%/75.2-76.7%; rumination: 89.6-91.6%/53.5-86.5%). Nonetheless both devices come with limitations and especially the AWT needs technological adaptations before applying it on animals in the wild. Nevertheless, looking at the prediction results, both are promising accelerometers for behavioral classification of giraffes. Therefore, these devices when applied to free-ranging animals, in combination with GPS tracking, can contribute greatly to the conservation of giraffes.
KW  - giraffe
KW  - triaxial acceleration
KW  - machine learning
KW  - random forests
KW  - behavior classification
KW  - giraffe conservation
Y1  - 2021
U6  - https://doi.org/10.3390/s21062229
SN  - 1424-8220
VL  - 21
IS  - 6
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Prill, Robert
A1  - Walter, Marina
A1  - Królikowska, Aleksandra
A1  - Becker, Roland
T1  - A systematic review of diagnostic accuracy and clinical applications of wearable movement sensors for knee joint rehabilitation
JF  - Sensors
N2  - In clinical practice, only a few reliable measurement instruments are available for monitoring knee joint rehabilitation. Advances to replace motion capturing with sensor data measurement have been made in the last years. Thus, a systematic review of the literature was performed, focusing on the implementation, diagnostic accuracy, and facilitators and barriers of integrating wearable sensor technology in clinical practices based on a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. For critical appraisal, the COSMIN Risk of Bias tool for reliability and measurement of error was used. PUBMED, Prospero, Cochrane database, and EMBASE were searched for eligible studies. Six studies reporting reliability aspects in using wearable sensor technology at any point after knee surgery in humans were included. All studies reported excellent results with high reliability coefficients, high limits of agreement, or a few detectable errors. They used different or partly inappropriate methods for estimating reliability or missed reporting essential information. Therefore, a moderate risk of bias must be considered. Further quality criterion studies in clinical settings are needed to synthesize the evidence for providing transparent recommendations for the clinical use of wearable movement sensors in knee joint rehabilitation.
KW  - wearable movement sensor
KW  - IMU
KW  - motion capture
KW  - reliability
KW  - clinical
KW  - orthopedic
Y1  - 2021
U6  - https://doi.org/10.3390/s21248221
SN  - 1424-8220
VL  - 21
IS  - 24
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Krüger, Stefanie
A1  - Schwarze, Michael
A1  - Baumann, Otto
A1  - Günter, Christina
A1  - Bruns, Michael
A1  - Kübel, Christian
A1  - Szabo, Dorothee Vinga
A1  - Meinusch, Rafael
A1  - Bermudez, Veronica de Zea
A1  - Taubert, Andreas
T1  - Bombyx mori silk/titania/gold hybrid materials for photocatalytic water splitting
BT  - combining renewable raw materials with clean fuels
JF  - Beilstein journal of nanotechnology
N2  - The synthesis, structure, and photocatalytic water splitting performance of two new titania (TiO2)/gold(Au)/Bombyx mori silk hybrid materials are reported. All materials are monoliths with diameters of up to ca. 4.5 cm. The materials are macroscopically homogeneous and porous with surface areas between 170 and 210 m(2)/g. The diameter of the TiO2 nanoparticles (NPs) - mainly anatase with a minor fraction of brookite - and the Au NPs are on the order of 5 and 7-18 nm, respectively. Addition of poly(ethylene oxide) to the reaction mixture enables pore size tuning, thus providing access to different materials with different photocatalytic activities. Water splitting experiments using a sunlight simulator and a Xe lamp show that the new hybrid materials are effective water splitting catalysts and produce up to 30 mmol of hydrogen per 24 h. Overall the article demonstrates that the combination of a renewable and robust scaffold such as B. mori silk with a photoactive material provides a promising approach to new monolithic photocatalysts that can easily be recycled and show great potential for application in lightweight devices for green fuel production.
KW  - Bombyx mori silk
KW  - gold
KW  - photocatalytic water splitting
KW  - titania
Y1  - 2018
U6  - https://doi.org/10.3762/bjnano.9.21
SN  - 2190-4286
VL  - 9
SP  - 187
EP  - 204
PB  - Beilstein-Institut zur Förderung der Chemischen Wissenschaften
CY  - Frankfurt, Main
ER  - 
TY  - JOUR
A1  - Yarman, Aysu
A1  - Kurbanoğlu, Sevinç
A1  - Zebger, Ingo
A1  - Scheller, Frieder W.
T1  - Simple and robust
BT  - the claims of protein sensing by molecularly imprinted polymers
JF  - Sensors and actuators : B, Chemical : an international journal devoted to research and development of chemical transducers
N2  - A spectrum of 7562 publications on Molecularly Imprinted Polymers (MIPs) has been presented in literature within the last ten years (Scopus, September 7, 2020). Around 10 % of the papers published on MIPs describe the recognition of proteins. The straightforward synthesis of MIPs is a significant advantage as compared with the preparation of enzymes or antibodies. MIPs have been synthesized from only one up to six functional monomers while proteins are made up of 20 natural amino acids. Furthermore, they can be synthesized against structures of low immunogenicity and allow multi-analyte measurements via multi-target synthesis. Electrochemical methods allow simple polymer synthesis, removal of the template and readout. Among the different sensor configurations electrochemical MIP-sensors provide the broadest spectrum of protein analytes. The sensitivity of MIP-sensors is sufficiently high for biomarkers in the sub-nanomolar region, nevertheless the cross-reactivity of highly abundant proteins in human serum is still a challenge. MIPs for proteins offer innovative tools not only for clinical and environmental analysis, but also for bioimaging, therapy and protein engineering.
KW  - Molecularly imprinted polymer
KW  - Plastibodies
KW  - Functional scaffolds
KW  - Biomimetic sensors
KW  - Proteins
Y1  - 2021
U6  - https://doi.org/10.1016/j.snb.2020.129369
SN  - 0925-4005
SN  - 1873-3077
VL  - 330
PB  - Elsevier Science
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Kuntze, Kim
A1  - Viljakka, Jani
A1  - Titov, Evgenii
A1  - Ahmed, Zafar
A1  - Kalenius, Elina
A1  - Saalfrank, Peter
A1  - Priimagi, Arri
T1  - Towards low-energy-light-driven bistable photoswitches
BT  - ortho-fluoroaminoazobenzenes
JF  - Photochemical & photobiological sciences / European Society for Photobiology
N2  - Thermally stable photoswitches that are driven with low-energy light are rare, yet crucial for extending the applicability of photoresponsive molecules and materials towards, e.g., living systems. Combined ortho-fluorination and -amination couples high visible light absorptivity of o-aminoazobenzenes with the extraordinary bistability of o-fluoroazobenzenes. Herein, we report a library of easily accessible o-aminofluoroazobenzenes and establish structure-property relationships regarding spectral qualities, visible light isomerization efficiency and thermal stability of the cis-isomer with respect to the degree of o-substitution and choice of amino substituent. We rationalize the experimental results with quantum chemical calculations, revealing the nature of low-lying excited states and providing insight into thermal isomerization. The synthesized azobenzenes absorb at up to 600 nm and their thermal cis-lifetimes range from milliseconds to months. The most unique example can be driven from trans to cis with any wavelength from UV up to 595 nm, while still exhibiting a thermal cis-lifetime of 81 days. <br /> [GRAPHICS] <br /> .
Y1  - 2022
U6  - https://doi.org/10.1007/s43630-021-00145-4
SN  - 1474-905X
SN  - 1474-9092
VL  - 21
IS  - 2
SP  - 159
EP  - 173
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Kaiser, Soraya
A1  - Grosse, Guido
A1  - Boike, Julia
A1  - Langer, Moritz
T1  - Monitoring the transformation of Arctic landscapes
BT  - automated shoreline change detection of lakes using very high resolution imagery
JF  - Remote sensing / Molecular Diversity Preservation International (MDPI)
N2  - Water bodies are a highly abundant feature of Arctic permafrost ecosystems and strongly influence their hydrology, ecology and biogeochemical cycling. While very high resolution satellite images enable detailed mapping of these water bodies, the increasing availability and abundance of this imagery calls for fast, reliable and automatized monitoring. This technical work presents a largely automated and scalable workflow that removes image noise, detects water bodies, removes potential misclassifications from infrastructural features, derives lake shoreline geometries and retrieves their movement rate and direction on the basis of ortho-ready very high resolution satellite imagery from Arctic permafrost lowlands. We applied this workflow to typical Arctic lake areas on the Alaska North Slope and achieved a successful and fast detection of water bodies. We derived representative values for shoreline movement rates ranging from 0.40-0.56 m yr(-1) for lake sizes of 0.10 ha-23.04 ha. The approach also gives an insight into seasonal water level changes. Based on an extensive quantification of error sources, we discuss how the results of the automated workflow can be further enhanced by incorporating additional information on weather conditions and image metadata and by improving the input database. The workflow is suitable for the seasonal to annual monitoring of lake changes on a sub-meter scale in the study areas in northern Alaska and can readily be scaled for application across larger regions within certain accuracy limitations.
KW  - change detection
KW  - shoreline movement rate
KW  - shoreline movement direction
KW  - arctic water bodies
KW  - permafrost lowlands
KW  - automated monitoring
KW  - North
KW  - Slope
KW  - very high resolution imagery
Y1  - 2021
U6  - https://doi.org/10.3390/rs13142802
SN  - 2072-4292
VL  - 13
IS  - 14
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Dannemann, Udo
T1  - Krisenvorstellungen
BT  - Einschätzungen und Überzeugungen von Lehrer/-innen zu den Herausforderungen unserer Gesellschaft
JF  - Zeitschrift für Didaktik der Gesellschaftswissenschaften
N2  - Der Beitrag stellt zentrale Ergebnisse der qualitativen Untersuchung zum Thema „Gesellschaftliche Herausforderungen im sozialen und im schulischen Raum“ dar. Dabei wird zunächst nur der erste Teil und damit das Erfahrungswissen im sozialen Raum beleuchtet. Neben einer kurzen Darstellung des theoretischen und methodischen Zugangs werden unterschiedliche Krisenverständnisse von Lehrer/-innen herausgestellt und auf sozialwissenschaftliche Erkenntnisse zurückgeführt. Der Rekurs auf die Krise(n) wird als Zugang genutzt, um gesellschaftliche He-rausforderungen zu identifizieren und Einschätzungen zu explizieren. In einem zweiten Schritt werden zwei Typen präsentiert, durch die exemplarisch konträre Vorstellungen zu unterschiedlichen gesellschaftlichen Herausforderungen und Krisen herausgestellt werden können. Durch die zwei Typen „progressive“ und „konservative Kritiker/-innen“ kann ein Spannungsfeld aufgemacht werden, auf dem die untersuchten Fälle verortet werden. Ziel ist es, Erfahrungswissen und die gesellschaftlichen Sichtweisen wie auch politischen Überzeugungen sichtbar und vergleichbar werden zu lassen. Diese bilden die Grundlage, um anschließend zu untersuchen,  wie  sich  Vorstellungen  und  Überzeugungen  auch  im  schulischen  Raum wiederfinden lassen. Ein erster Einblick wird am Ende des Beitrags durch die Darstellung eines exemplarischen Falls gewährt.
KW  - Krise
KW  - Gesellschaftswissenschaften
KW  - Didaktik
KW  - Didaktik der Gesellschaftswissenschaften
KW  - Sinnbildung
Y1  - 2022
U6  - https://doi.org/10.46499/2079.2533
SN  - 2191-0766
SN  - 2749-487X
VL  - 13
IS  - 2
SP  - 77
EP  - 98
PB  - Wochenschau Verlag
CY  - Frankfurt, M.
ER  - 
TY  - JOUR
A1  - Ekatushabe, Margaret
A1  - Kwarikunda, Diana
A1  - Muwonge, Charles Magoba
A1  - Ssenyonga, Joseph
A1  - Schiefele, Ulrich
T1  - Relations between perceived teacher’s autonomy support, cognitive appraisals and boredom in physics learning among lower secondary school students
JF  - International journal of STEM education
N2  - Background Boredom during learning activities has the potential of impeding attention, motivation, learning and eventually achievement. Yet, research focusing on its possible antecedents seems to have received less attention especially within the physics domain. Based on assumptions of the Control Value Theory of Achievement Emotions (CVTAE), this study aimed at examining gender differences and structural relationships between students' reported perceived teacher autonomy support (PTAS), cognitive appraisals (self-efficacy and task value) and learning-related boredom in physics. A sample of 375 (56% females) randomly selected 9(th) grade students (mean age = 15.03 years; SD = 1.02) from five secondary schools in Masaka district of Uganda took part in the study. Results Data collected from students' self-reports using standardised instruments revealed that higher levels of PTAS, self-efficacy, and task value were significantly associated with lower levels of boredom during physics learning. Females reported significantly greater task value for learning physics than the males. Self-efficacy (beta = - .10, p < .05) and task value (beta = - .09, p < .01) partially mediated the relationship between PTAS and boredom. PTAS showed significant direct negative contributions to boredom (beta = - .34, p < .001). Conclusion These findings provide support for theory and practice about the importance of promoting autonomy among students by adjusting instructional behaviours among teachers of physics. Teacher autonomy supportive behaviours influence formation of students' beliefs about ability, subjective value and learning-related boredom in physics. Implications and suggestions for further research are also discussed in this paper.
KW  - Teacher autonomy support
KW  - Cognitive appraisals
KW  - Self-efficacy
KW  - Task
KW  - value
KW  - Boredom
KW  - Gender
KW  - Physics
Y1  - 2021
U6  - https://doi.org/10.1186/s40594-021-00272-5
SN  - 2196-7822
VL  - 8
IS  - 1
PB  - SpringerOpen
CY  - Berlin ; Heidelberg [u.a.]
ER  - 
TY  - GEN
A1  - Milewski, Robert
A1  - Chabrillat, Sabine
A1  - Bookhagen, Bodo
T1  - Analyses of Namibian Seasonal Salt Pan Crust Dynamics and Climatic Drivers Using Landsat 8 Time-Series and Ground Data
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Salt pans are highly dynamic environments that are difficult to study by in situ methods because of their harsh climatic conditions and large spatial areas. Remote sensing can help to elucidate their environmental dynamics and provide important constraints regarding their sedimentological, mineralogical, and hydrological evolution. This study utilizes spaceborne multitemporal multispectral optical data combined with spectral endmembers to document spatial distribution of surface crust types over time on the Omongwa pan located in the Namibian Kalahari. For this purpose, 49 surface samples were collected for spectral and mineralogical characterization during three field campaigns (2014–2016) reflecting different seasons and surface conditions of the salt pan. An approach was developed to allow the spatiotemporal analysis of the salt pan crust dynamics in a dense time-series consisting of 77 Landsat 8 cloud-free scenes between 2014 and 2017, covering at least three major wet–dry cycles. The established spectral analysis technique Sequential Maximum Angle Convex Cone (SMACC) extraction method was used to derive image endmembers from the Landsat time-series stack. Evaluation of the extracted endmember set revealed that the multispectral data allowed the differentiation of four endmembers associated with mineralogical mixtures of the crust’s composition in dry conditions and three endmembers associated with flooded or muddy pan conditions. The dry crust endmember spectra have been identified in relation to visible, near infrared, and short-wave infrared (VNIR–SWIR) spectroscopy and X-ray diffraction (XRD) analyses of the collected surface samples. According these results, the spectral endmembers are interpreted as efflorescent halite crust, mixed halite–gypsum crust, mixed calcite quartz sepiolite crust, and gypsum crust. For each Landsat scene the spatial distribution of these crust types was mapped with the Spectral Angle Mapper (SAM) method and significant spatiotemporal dynamics of the major surface crust types were observed. Further, the surface crust dynamics were analyzed in comparison with the pan’s moisture regime and other climatic parameters. The results show that the crust dynamics are mainly driven by flooding events in the wet season, but are also influenced by temperature and aeolian activity in the dry season. The approach utilized in this study combines the advantages of multitemporal satellite data for temporal event characterization with advantages from hyperspectral methods for the image and ground data analyses that allow improved mineralogical differentiation and characterization.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 988 
KW  - salt pan
KW  - playa
KW  - spectral analysis
KW  - crust
KW  - saline pan cycle
KW  - evaporites
KW  - time-series mapping
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-475685
SN  - 1866-8372
IS  - 988
ER  - 
TY  - JOUR
A1  - Milewski, Robert
A1  - Chabrillat, Sabine
A1  - Bookhagen, Bodo
T1  - Analyses of Namibian Seasonal Salt Pan Crust Dynamics and Climatic Drivers Using Landsat 8 Time-Series and Ground Data
JF  - Remote Sensing
N2  - Salt pans are highly dynamic environments that are difficult to study by in situ methods because of their harsh climatic conditions and large spatial areas. Remote sensing can help to elucidate their environmental dynamics and provide important constraints regarding their sedimentological, mineralogical, and hydrological evolution. This study utilizes spaceborne multitemporal multispectral optical data combined with spectral endmembers to document spatial distribution of surface crust types over time on the Omongwa pan located in the Namibian Kalahari. For this purpose, 49 surface samples were collected for spectral and mineralogical characterization during three field campaigns (2014–2016) reflecting different seasons and surface conditions of the salt pan. An approach was developed to allow the spatiotemporal analysis of the salt pan crust dynamics in a dense time-series consisting of 77 Landsat 8 cloud-free scenes between 2014 and 2017, covering at least three major wet–dry cycles. The established spectral analysis technique Sequential Maximum Angle Convex Cone (SMACC) extraction method was used to derive image endmembers from the Landsat time-series stack. Evaluation of the extracted endmember set revealed that the multispectral data allowed the differentiation of four endmembers associated with mineralogical mixtures of the crust’s composition in dry conditions and three endmembers associated with flooded or muddy pan conditions. The dry crust endmember spectra have been identified in relation to visible, near infrared, and short-wave infrared (VNIR–SWIR) spectroscopy and X-ray diffraction (XRD) analyses of the collected surface samples. According these results, the spectral endmembers are interpreted as efflorescent halite crust, mixed halite–gypsum crust, mixed calcite quartz sepiolite crust, and gypsum crust. For each Landsat scene the spatial distribution of these crust types was mapped with the Spectral Angle Mapper (SAM) method and significant spatiotemporal dynamics of the major surface crust types were observed. Further, the surface crust dynamics were analyzed in comparison with the pan’s moisture regime and other climatic parameters. The results show that the crust dynamics are mainly driven by flooding events in the wet season, but are also influenced by temperature and aeolian activity in the dry season. The approach utilized in this study combines the advantages of multitemporal satellite data for temporal event characterization with advantages from hyperspectral methods for the image and ground data analyses that allow improved mineralogical differentiation and characterization.
KW  - salt pan
KW  - playa
KW  - spectral analysis
KW  - crust
KW  - saline pan cycle
KW  - evaporites
KW  - time-series mapping
Y1  - 2019
U6  - https://doi.org/10.3390/rs12030474
SN  - 2072-4292
IS  - 3
PB  - MDPI
CY  - Basel
ER  - 
TY  - GEN
A1  - Krüger, Stefanie
A1  - Schwarze, Michael
A1  - Baumann, Otto
A1  - Günter, Christina
A1  - Bruns, Michael
A1  - Kübel, Christian
A1  - Szabó, Dorothée Vinga
A1  - Meinusch, Rafael
A1  - de Zea Bermudez, Verónica
A1  - Taubert, Andreas
T1  - Bombyx mori silk/titania/gold hybrid materials for photocatalytic water splitting
BT  - combining renewable raw materials with clean fuels
T2  - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe
N2  - The synthesis, structure, and photocatalytic water splitting performance of two new titania (TiO 2 )/gold(Au)/Bombyx mori silk hybrid materials are reported. All materials are monoliths with diameters of up to ca. 4.5 cm. The materials are macroscopically homogeneous and porous with surface areas between 170 and 210 m 2/g. The diameter of the TiO 2 nanoparticles (NPs) – mainly anatase with a minor fraction of brookite – and the Au NPs are on the order of 5 and 7–18 nm, respectively. Addition of poly(ethylene oxide) to the reaction mixture enables pore size tuning, thus providing access to different materials with different photocatalytic activities. Water splitting experiments using a sunlight simulator and a Xe lamp show that the new hybrid materials are effective water splitting catalysts and produce up to 30 mmol of hydrogen per 24 h. Overall the article demonstrates that the combination of a renewable and robust scaffold such as B. mori silk with a photoactive material provides a promising approach to new monolithic photocatalysts that can easily be recycled and show great potential for application in lightweight devices for green fuel production.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 581 
KW  - Bombyx mori silk
KW  - gold
KW  - photocatalytic water splitting
KW  - titania
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-423499
SN  - 1866-8372
IS  - 581
ER  - 
TY  - JOUR
A1  - Apergi, Maria
A1  - Zimmermann, Eva
A1  - Weko, Silvia
A1  - Lilliestam, Johan
T1  - Is renewable energy technology trade more or less conflictive than other trade?
JF  - Energy policy
N2  - Renewable energy changes the geopolitics of energy: whereas access to fossil fuel resources were key in the past, control over technology and industry will be key in the future. Consequently, different scholars have predicted that a growing focus on renewables will increase or decrease conflict in the energy sector, with no consensus on which is most likely. Here, we investigate the degree of conflict in renewable energy technology (RET) trade by analyzing data on 7041 trade conflicts 1995–2020, guided by two sets of theory-driven hypotheses. We show that RET trade is associated with more, longer, and more intense trade conflicts than other trade conflicts for 1995–2016. This supports the neorealist, geo-economic view of countries being willing to risk conflict to increase their share of a market rather than avoiding conflicts to increase the overall market size. It also contradicts the view that renewables will reduce conflict: at least in the past and regarding trade, it has increased rather than decreased conflict. For 2017–2020, this trend is reversed and RET trade became significantly less conflictive than other trade. Our findings imply that improved conflict-resolution institutions for RET are needed. We also suggest establishing specific institutions to govern trade in immature technologies.
Y1  - 2023
U6  - https://doi.org/10.1016/j.enpol.2023.113538
SN  - 0301-4215
SN  - 1873-6777
VL  - 177
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Kar, Manaswita
A1  - Körzdörfer, Thomas
T1  - Computational high throughput screening of inorganic cation based halide perovskites for perovskite only tandem solar cells
JF  - Materials Research Express
N2  - We search for homovalent alternatives for A, B, and X-ions in ABX(3) type inorganic halide perovskites suitable for tandem solar cell applications. We replace the conventional A-site organic cation CH3NH3, by 3 inorganic cations, Cs, K, and Rb, and the B site consists of metals; Cd, Hg, Ge, Pb, and Sn This work is built on our previous high throughput screening of hybrid perovskite materials (Kar et al 2018 J. Chem. Phys. 149, 214701). By performing a systematic screening study using Density Functional Theory (DFT) methods, we found 11 suitable candidates; 2 Cs-based, 3 K-based and 6 Rb-based that are suitable for tandem solar cell applications.
KW  - inorganic perovskites
KW  - tandem solar cells
KW  - density functional theory
Y1  - 2020
U6  - https://doi.org/10.1088/2053-1591/ab8c0d
SN  - 2053-1591
VL  - 7
IS  - 5
SP  - 1
EP  - 10
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Süsser, Diana
A1  - Martin, Nick
A1  - Stavrakas, Vassilis
A1  - Gaschnig, Hannes
A1  - Talens-Peiró, Laura
A1  - Flamos, Alexandros
A1  - Madrid-López, Cristina
A1  - Lilliestam, Johan
T1  - Why energy models should integrate social and environmental factors
BT  - assessing user needs, omission impacts, and real-word accuracy in the European Union
JF  - Energy research & social science
N2  - Energy models are used to inform and support decisions within the transition to climate neutrality. In recent years, such models have been criticised for being overly techno-centred and ignoring environmental and social factors of the energy transition. Here, we explore and illustrate the impact of ignoring such factors by comparing model results to model user needs and real-world observations. We firstly identify concrete user needs for better representation of environmental and social factors in energy modelling via interviews, a survey and a workshop. Secondly, we explore and illustrate the effects of omitting non-techno-economic factors in modelling by contrasting policy-targeted scenarios with reality in four EU case study examples. We show that by neglecting environmental and social factors, models risk generating overly optimistic and potentially misleading results, for example by suggesting transition speeds far exceeding any speeds observed, or pathways facing hard-to-overcome resource constraints. As such, modelled energy transition pathways that ignore such factors may be neither desirable nor feasible from an environmental and social perspective, and scenarios may be irrelevant in practice. Finally, we discuss a sample of recent energy modelling innovations and call for continued and increased efforts for improved approaches that better represent environmental and social factors in energy modelling and increase the relevance of energy models for informing policymaking.
KW  - energy modelling
KW  - energy planning
KW  - energy policy
KW  - ecological crisis
KW  - social acceptance
KW  - environmental impacts
Y1  - 2022
U6  - https://doi.org/10.1016/j.erss.2022.102775
SN  - 2214-6296
VL  - 92
SP  - 102775
EP  - 102775
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - De Schrijver, Lotte
A1  - Vander Beken, Tom
A1  - Krahé, Barbara
A1  - Keygnaert, Ines
T1  - Prevalence of sexual violence in migrants, applicants for international protection, and refugees in Europe
BT  - a critical interpretive synthesis of the evidence
T2  - Postprints der Universität Potsdam : Humanwissenschaftliche Reihe
N2  - (1) Background: Sexual violence (SV) is a major public health problem, with negative socio-economic, physical, mental, sexual, and reproductive health consequences. Migrants, applicants for international protection, and refugees (MARs) are vulnerable to SV. Since many European countries are seeing high migratory pressure, the development of prevention strategies and care paths focusing on victimised MARs is highly needed. To this end, this study reviews evidence on the prevalence of SV among MAR groups in Europe and the challenges encountered in research on this topic. (2) Methods: A critical interpretive synthesis of 25 peer-reviewed academic studies and 22 relevant grey literature documents was conducted based on a socio-ecological model. (3) Results: Evidence shows that SV is highly frequent in MARs in Europe, yet comparison with other groups is still difficult. Methodologically and ethically sound representative studies comparing between populations are still lacking. Challenges in researching SV in MARs are located at the intrapersonal, interpersonal, community, societal, and policy levels. (4) Conclusions: Future research should start with a clear definition of the concerned population and acts of SV to generate comparable data. Participatory qualitative research approaches could be applied to better grasp the complexity of interplaying determinants of SV in MARs.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 674 
KW  - sexual violence
KW  - migrants
KW  - refugees
KW  - asylum seekers
KW  - applicants for international protection
KW  - Europe
KW  - prevalence
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-459733
SN  - 1866-8364
IS  - 674
ER  - 
TY  - JOUR
A1  - Chatterjee, Souran
A1  - Stavrakas, Vassilis
A1  - Oreggioni, Gabriel
A1  - Süsser, Diana
A1  - Staffell, Iain
A1  - Lilliestam, Johan
A1  - Molnar, Gergely
A1  - Flamos, Alexandros
A1  - Ürge-Vorsatz, Diana
T1  - Existing tools, user needs and required model adjustments for energy demand modelling of a carbon-neutral Europe
JF  - Energy research & social science
N2  - To achieve the European Union's target for climate neutrality by 2050 reduced energy demand will make the transition process faster and cheaper. The role of policies that support energy efficiency measures and demand-side management practices will be critical and to ensure that energy demand models are relevant to policymakers and other end-users, understanding how to further improve the models and whether they are tailored to user needs to support efficient decision-making processes is crucial. So far though, no scientific studies have examined the key user needs for energy demand modelling in the context of the climate neutrality targets. In this article we address this gap using a multi-method approach based on empirical and desk research. Through survey and stakeholder meetings and workshops we identify user needs of different stakeholder groups, and we highlight the direction in which energy demand models need to be improved to be relevant to their users. Through a detailed review of existing energy demand models, we provide a full understanding of the key characteristics and capabilities of existing tools, and we identify their limitations and gaps. Our findings show that classical demand-related questions remain important to model users, while most of the existing models can answer these questions. Furthermore, we show that some of the user needs related to sectoral demand modelling, dictated by the latest policy developments, are under-researched and are not addressed by existing tools.
KW  - energy demand
KW  - climate neutrality
KW  - demand-side management
KW  - model adjustments
KW  - energy demand modelling
Y1  - 2022
U6  - https://doi.org/10.1016/j.erss.2022.102662
SN  - 2214-6296
VL  - 90
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Spelzhausen, Simon
A1  - Ionian, Mario-Rafael
A1  - Gerhard, Reimund
A1  - Plath, Ronald
T1  - Time-resolved measurement of space-charge evolution in dielectric films or slabs by means of repeatable laser-induced pressure pulses
JF  - Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques
N2  - A new variant of the Laser-Induced Pressure-Pulse (LIPP) method for repeatable, time-resolved space-charge profile measurements is proposed and demonstrated. Automated deposition of a fresh laser-target film before each illumination leads to good repeatability of the LIPP and thus allows for the detection of time-resolved changes in the space-charge distribution over many hours. We describe and discuss the experimental setup and its features, compare the repeatability of the LIPP measurements on the same sample without and with re-preparation of the test cell, and present the time-resolved evolution of the space-charge profile in a two-layer arrangement of a silicone-grease and a silicone-elastomer film as an example. Finally, the temperature dependence of the space-charge evolution during polarization under high voltage and during depolarization in short circuit is shown. Possible uses and future developments of the new LIPP approach are also discussed.
Y1  - 2020
U6  - https://doi.org/10.1063/1.5142443
SN  - 0034-6748
SN  - 1089-7623
VL  - 91
IS  - 5
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Gerhard, Reimund
T1  - 50 years of International Symposia on Electrets from 1967 to 2017
BT  - a global history
JF  - IEEE electrical insulation magazine / Institute of Electrical and Electronics Engineers
N2  - The prehistory of electrets is not known yet, but it is quite likely that the electrostatic charging behavior of amber (Greek: τò ηλεκτρoν, i.e., “electron”) already was familiar to people in ancient cultures (China, Egypt, Greece, etc.), before the Greek philosopher and scientist Thales of Miletus (6th century BCE)-or rather his disciples and followers-reported it in writing (cf. Figure 1). More than two millennia later, William Gilbert (1544–1603), the physician of Queen Elizabeth I, coined the term “electric” in his book De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure (1600) for dielectric materials that attract like amber and that included sulfur and glass [1]. The second half of the 18th century saw the invention of the electrophorus or electrophore [2], a capacitive electret device, in 1762 by Johan Carl Wilcke (1732–1796).
Y1  - 2021
U6  - https://doi.org/10.1109/MEI.2021.9352710
SN  - 0883-7554
SN  - 1558-4402
VL  - 37
IS  - 2
SP  - 50
EP  - 55
PB  - IEEE
CY  - New York, NY
ER  - 
TY  - JOUR
A1  - Raman Venkatesan, Thulasinath
A1  - Gerhard, Reimund
T1  - Origin of the mid-temperature transition in vinylidenefluoride-based ferro-, pyro- and piezoelectric homo-, co- and ter-polymers
JF  - Materials Research Express
N2  - The existence of an intermediate transition between the glass and the Curie/melting temperatures in Poly(vinylidene fluoride) (PVDF) and some of its co- and ter-polymers has been reported by several authors. In spite (or because?) of various different explanations in the literature, the origins of the transition are still not clear. Here, we try to understand the extra transition in more detail and study it with thermal and dielectric methods on PVDF, on its co-polymers with trifluoroethylene (P(VDF-TrFE)) and tetrafluoroethylene (P(VDF-TFE)), and on its ter-polymer with trifluoroethylene and chlorofluoroethylene (P(VDF-TrFE-CFE). Based on interpretations from the literature and our experimental studies, we propose the new hypothesis that the intermediate transition should have several interrelated origins. Especially since the relevant range is not far above room temperature, better understanding and control of their properties may also have practical implications for the use of the respective polymer materials in devices.
KW  - mid-temperature transition
KW  - vinylidenefluoride (VDF)-based polymers
KW  - Differential Scanning Calorimetry (DSC)
KW  - Dielectric Relaxation Spectroscopy (DRS)
KW  - ferroelectric polymers
KW  - pyroelectric polymers
KW  - piezoelectric polymers
Y1  - 2020
U6  - https://doi.org/10.1088/2053-1591/ab842c
SN  - 2053-1591
VL  - 7
PB  - IOP Publ.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Wang, Ningzhen
A1  - Daniels, Robert
A1  - Connelly, Liam
A1  - Sotzing, Michael
A1  - Wu, Chao
A1  - Gerhard, Reimund
A1  - Sotzing, Gregory A.
A1  - Cao, Yang
T1  - All-organic flexible ferroelectret nanogenerator with fabric-based electrodes for self-powered body area networks
JF  - Small : nano micro
N2  - Due to their electrically polarized air-filled internal pores, optimized ferroelectrets exhibit a remarkable piezoelectric response, making them suitable for energy harvesting. Expanded polytetrafluoroethylene (ePTFE) ferroelectret films are laminated with two fluorinated-ethylene-propylene (FEP) copolymer films and internally polarized by corona discharge. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)-coated spandex fabric is employed for the electrodes to assemble an all-organic ferroelectret nanogenerator (FENG). The outer electret-plus-electrode double layers form active device layers with deformable electric dipoles that strongly contribute to the overall piezoelectric response in the proposed concept of wearable nanogenerators. Thus, the FENG with spandex electrodes generates a short-circuit current which is twice as high as that with aluminum electrodes. The stacking sequence spandex/FEP/ePTFE/FEP/ePTFE/FEP/spandex with an average pore size of 3 mu m in the ePTFE films yields the best overall performance, which is also demonstrated by the displacement-versus-electric-field loop results. The all-organic FENGs are stable up to 90 degrees C and still perform well 9 months after being polarized. An optimized FENG makes three light emitting diodes (LEDs) blink twice with the energy generated during a single footstep. The new all-organic FENG can thus continuously power wearable electronic devices and is easily integrated, for example, with clothing, other textiles, or shoe insoles.
KW  - all-organic ferroelectret nanogenerator (FENG)
KW  - all-organic
KW  - piezoelectric nanogenerator (PENG)
KW  - expanded polytetrafluoroethylene
KW  - ferroelectret
KW  - micro-energy harvesting
KW  - (PEDOT
KW  - PSS)-coated porous
KW  - fabric electrodes
KW  - wearable electronics
Y1  - 2021
U6  - https://doi.org/10.1002/smll.202103161
SN  - 1613-6810
SN  - 1613-6829
VL  - 17
IS  - 33
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Stubning, Tobias
A1  - Denes, Istvan
A1  - Gerhard, Reimund
T1  - Tuning electro-mechanical properties of EAP-based haptic actuators by adjusting layer thickness and number of stacked layers
BT  - a comparison
JF  - Engineering research express
N2  - In our fast-changing world, human-machine interfaces (HMIs) are of ever-increasing importance. Among the most ubiquitous examples are touchscreens that most people are familiar with from their smartphones. The quality of such an HMI can be improved by adding haptic feedback-an imitation of using mechanical buttons-to the touchscreen. Thin-film actuators on the basis of electro-mechanically active polymers (EAPs), with the electroactive material sandwiched between two compliant electrodes, offer a promising technology for haptic surfaces. In thin-film technology, the thickness and the number of stacked layers of the electroactive dielectric are key parameters for tuning a system. Therefore, we have experimentally investigated the influence of the thickness of a single EAP layer on the electrical and the electro-mechanical performance of the transducer. In order to achieve high electro-mechanical actuator outputs, we have employed relaxor-ferroelectric ter-fluoropolymers that can be screen-printed. By means of a model-based approach, we have also directly compared single- and multi-layer actuators, thus providing guidelines for optimized transducer configurations with respect to the system requirements of haptic applications for which the operation frequency is of particular importance.
KW  - haptic feedback
KW  - vinylidenefluoride(VDF)-based polymers
KW  - screen-printed
KW  - systems
KW  - thin-film actuators
KW  - multi-layer systems
KW  - equivalent-circuit
KW  - modelling
KW  - electro-mechanically active polymers
Y1  - 2021
U6  - https://doi.org/10.1088/2631-8695/abd286
SN  - 2631-8695
VL  - 3
IS  - 1
PB  - Institute of Physics
CY  - London
ER  - 
TY  - JOUR
A1  - Raman Venkatesan, Thulasinath
A1  - Wübbenhorst, Michael
A1  - Gerhard, Reimund
T1  - Structure-property relationships in three-phase relaxor-ferroelectric terpolymers
JF  - Ferroelectrics
N2  - Poly(vinylidenefluoride-trifluoroethylene)-based (P(VDF-TrFE)-based) terpolymers represent a new class of electroactive polymer materials that are relaxor-ferroelectric (RF) polymers and that offer unique and attractive property combinations in comparison with conventional ferroelectric polymers. The RF state is achieved by introducing a fluorine-containing termonomer as a "defect" into the ferroelectric P(VDF-TrFE) copolymer, which reduces the interaction between the VDF/TrFE dipoles. The resulting terpolymer exhibits a low Curie transition temperature and small remanent and coercive fields yielding a slim hysteresis loop that is typical for RF materials. Though the macroscopic behavior is similar to RF ceramics, the mechanisms of relaxor ferroelectricity in semi-crystalline polymers are different and not fully understood yet. Structure-property relationships play an important role in RF terpolymers, as they govern the final RF properties. Hence, a review of important characteristics, previous studies and relevant developments of P(VDF-TrFE)-based terfluoropolymers with either chlorofluoroethylene (CFE) or chlorotrifluoroethylene (CTFE) as the termonomer is deemed useful. The role of the termonomer and of its composition, as well as the effects of the processing conditions on the semi-crystalline structure which in turn affects the final RF properties are discussed in detail. In addition, the presence of noteworthy transition(s) in the mid-temperature range and the influence of preparation conditions on those transitions are reviewed. A better understanding of the fundamental aspects affecting the semi-crystalline structures will help to elucidate the nature of RF activity in VDF-based terpolymers and also help to further improve their applications-relevant electroactive properties.
KW  - Relaxor-ferroelectric (RF) fluoropolymers
KW  - structure-property
KW  - relationships
KW  - Curie transition
KW  - dielectric hysteresis
KW  - thermal
KW  - processing
KW  - mid-temperature transition(s)
Y1  - 2022
U6  - https://doi.org/10.1080/00150193.2021.2014260
SN  - 0015-0193
SN  - 1563-5112
VL  - 586
IS  - 1
SP  - 60
EP  - 81
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Hwang, Jinyeon
A1  - Zhang, Wuyong
A1  - Youk, Sol
A1  - Schutjajew, Konstantin
A1  - Oschatz, Martin
T1  - Understanding structure-property relationships under experimental conditions for the optimization of lithium-ion capacitor anodes based on all-carbon-composite materials
JF  - Energy technology : generation, conversion, storage, distribution
N2  - The nanoscale combination of a conductive carbon and a carbon-based material with abundant heteroatoms for battery electrodes is a method to overcome the limitation that the latter has high affinity to alkali metal ions but low electronic conductivity. The synthetic protocol and the individual ratios and structures are important aspects influencing the properties of such multifunctional compounds. Their interplay is, herein, investigated by infiltration of a porous ZnO-templated carbon (ZTC) with nitrogen-rich carbon obtained by condensation of hexaazatriphenylene-hexacarbonitrile (HAT-CN) at 550-1000 degrees C. The density of lithiophilic sites can be controlled by HAT-CN content and condensation temperature. Lithium storage properties are significantly improved in comparison with those of the individual compounds and their physical mixtures. Depending on the uniformity of the formed composite, loading ratio and condensation temperature have different influence. Most stable operation at high capacity per used monomer is achieved with a slowly dried composite with an HAT-CN:ZTC mass ratio of 4:1, condensed at 550 degrees C, providing more than 400 mAh g(-1) discharge capacity at 0.1 A g(-1) and a capacity retention of 72% after 100 cycles of operation at 0.5 A g(-1) due to the homogeneity of the composite and high content of lithiophilic sites.
KW  - anodes
KW  - hybrid materials
KW  - nitrogen-doped carbon
KW  - porous carbon
KW  - lithium-ion capacitors
Y1  - 2021
U6  - https://doi.org/10.1002/ente.202001054
SN  - 2194-4296
VL  - 9
IS  - 3
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Malik, Aman
A1  - Bertram, Christoph
A1  - Kriegler, Elmar
A1  - Luderer, Gunnar
T1  - Climate policy accelerates structural changes in energy employment
JF  - Energy policy
N2  - The employment implications of decarbonizing the energy sector have received far less attention than the technology dimension of the transition, although being of critical importance to policymakers. In this work, we adapt a methodology based on employment factors to project future changes in quantity and composition of direct energy supply jobs for two scenarios - (1) relatively weak emissions reductions as pledged in the nationally determined contributions (NDC) and (2) stringent reductions compatible with the 1.5 °C target. We find that in the near-term the 1.5°C-compatible scenario results in a net increase in jobs through gains in solar and wind jobs in construction, installation, and manufacturing, despite significant losses in coal fuel supply; eventually leading to a peak in total direct energy jobs in 2025. In the long run, improvements in labour productivity lead to a decrease of total direct energy employment compared to today, however, total jobs are still higher in a 1.5 °C than in an NDC scenario. Operation and maintenance jobs dominate future jobs, replacing fuel supply jobs. The results point to the need for active policies aimed at retraining, both inside and outside the renewable energy sector, to complement climate policies within the concept of a “just transition”.
KW  - energy supply
KW  - employment
KW  - just transition
KW  - political feasibility
KW  - mitigation pathways
KW  - integrated assessment models
Y1  - 2021
U6  - https://doi.org/10.1016/j.enpol.2021.112642
SN  - 0301-4215
VL  - 159
PB  - Elsevier Science
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Raman Venkatesan, Thulasinath
A1  - Gerhard, Reimund
T1  - Origin of the mid-temperature transition in vinylidenefluoride-based ferro-, pyro- and piezoelectric homo-, co- and ter-polymers
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - The existence of an intermediate transition between the glass and the Curie/melting temperatures in Poly(vinylidene fluoride) (PVDF) and some of its co- and ter-polymers has been reported by several authors. In spite (or because?) of various different explanations in the literature, the origins of the transition are still not clear. Here, we try to understand the extra transition in more detail and study it with thermal and dielectric methods on PVDF, on its co-polymers with trifluoroethylene (P(VDF-TrFE)) and tetrafluoroethylene (P(VDF-TFE)), and on its ter-polymer with trifluoroethylene and chlorofluoroethylene (P(VDF-TrFE-CFE). Based on interpretations from the literature and our experimental studies, we propose the new hypothesis that the intermediate transition should have several interrelated origins. Especially since the relevant range is not far above room temperature, better understanding and control of their properties may also have practical implications for the use of the respective polymer materials in devices.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 977 
KW  - mid-temperature transition
KW  - vinylidenefluoride (VDF)-based polymers
KW  - Differential Scanning Calorimetry (DSC)
KW  - Dielectric Relaxation Spectroscopy (DRS)
KW  - ferroelectric polymers
KW  - pyroelectric polymers
KW  - piezoelectric polymers
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-474672
SN  - 1866-8372
IS  - 977
ER  - 
TY  - GEN
A1  - Lagriffoul, Fabien
A1  - Andres, Benjamin
T1  - Combining task and motion planning
BT  - a culprit detection problem
T2  - The international journal of robotics research
N2  - Solving problems combining task and motion planning requires searching across a symbolic search space and a geometric search space. Because of the semantic gap between symbolic and geometric representations, symbolic sequences of actions are not guaranteed to be geometrically feasible. This compels us to search in the combined search space, in which frequent backtracks between symbolic and geometric levels make the search inefficient. We address this problem by guiding symbolic search with rich information extracted from the geometric level through culprit detection mechanisms.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 422 
KW  - combined task and motion planning
KW  - manipulation planning
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-405126
VL  - 35
IS  - 8
ER  - 
TY  - GEN
A1  - Wang, Xuepu
A1  - Sperling, Marcel
A1  - Reifarth, Martin
A1  - Böker, Alexander
T1  - Shaping metallic nanolattices
BT  - Design by microcontact printing from wrinkled stamps
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - A method for the fabrication of well-defined metallic nanostructures is presented here in a simple and straightforward fashion. As an alternative to lithographic techniques, this routine employs microcontact printing utilizing wrinkled stamps, which are prepared from polydimethylsiloxane (PDMS), and includes the formation of hydrophobic stripe patterns on a substrate via the transfer of oligomeric PDMS. Subsequent backfilling of the interspaces between these stripes with a hydroxyl-functional poly(2-vinyl pyridine) then provides the basic pattern for the deposition of citrate-stabilized gold nanoparticles promoted by electrostatic interaction. The resulting metallic nanostripes can be further customized by peeling off particles in a second microcontact printing step, which employs poly(ethylene imine) surface-decorated wrinkled stamps, to form nanolattices. Due to the independent adjustability of the period dimensions of the wrinkled stamps and stamp orientation with respect to the substrate, particle arrays on the (sub)micro-scale with various kinds of geometries are accessible in a straightforward fashion. This work provides an alternative, cost-effective, and scalable surface-patterning technique to fabricate nanolattice structures applicable to multiple types of functional nanoparticles. Being a top-down method, this process could be readily implemented into, e.g., the fabrication of optical and sensing devices on a large scale.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1391 
KW  - gold nanoparticle assembly
KW  - hydroxyl-functional poly(2-vinyl pyridine)
KW  - metallic nanolattices
KW  - microcontact printing
KW  - oligomeric polydimethylsiloxane
KW  - polydimethylsiloxane wrinkles
KW  - wrinkled stamps
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-514341
SN  - 1866-8372
IS  - 11
ER  - 
TY  - JOUR
A1  - Kaitoua, Abdulrahman
A1  - Rabl, Tilmann
A1  - Markl, Volker
T1  - A distributed data exchange engine for polystores
JF  - Information technology : methods and applications of informatics and information technology
JF  - Information technology : Methoden und innovative Anwendungen der Informatik und Informationstechnik
N2  - There is an increasing interest in fusing data from heterogeneous sources. Combining data sources increases the utility of existing datasets, generating new information and creating services of higher quality. A central issue in working with heterogeneous sources is data migration: In order to share and process data in different engines, resource intensive and complex movements and transformations between computing engines, services, and stores are necessary.
Muses is a distributed, high-performance data migration engine that is able to interconnect distributed data stores by forwarding, transforming, repartitioning, or broadcasting data among distributed engines' instances in a resource-, cost-, and performance-adaptive manner. As such, it performs seamless information sharing across all participating resources in a standard, modular manner. We show an overall improvement of 30 % for pipelining jobs across multiple engines, even when we count the overhead of Muses in the execution time. This performance gain implies that Muses can be used to optimise large pipelines that leverage multiple engines.
KW  - distributed systems
KW  - data migration
KW  - data transformation
KW  - big data
KW  - engine
KW  - data integration
Y1  - 2020
U6  - https://doi.org/10.1515/itit-2019-0037
SN  - 1611-2776
SN  - 2196-7032
VL  - 62
IS  - 3-4
SP  - 145
EP  - 156
PB  - De Gruyter
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Arguello de Souza, Felipe Augusto
A1  - Samprogna Mohor, Guilherme
A1  - Guzman Arias, Diego Alejandro
A1  - Sarmento Buarque, Ana Carolina
A1  - Taffarello, Denise
A1  - Mendiondo, Eduardo Mario
T1  - Droughts in São Paulo
BT  - challenges and lessons for a water-adaptive society
JF  - Urban water journal
N2  - Literature has suggested that droughts and societies are mutually shaped and, therefore, both require a better understanding of their coevolution on risk reduction and water adaptation. Although the Sao Paulo Metropolitan Region drew attention because of the 2013-2015 drought, this was not the first event. This paper revisits this event and the 1985-1986 drought to compare the evolution of drought risk management aspects. Documents and hydrological records are analyzed to evaluate the hazard intensity, preparedness, exposure, vulnerability, responses, and mitigation aspects of both events. Although the hazard intensity and exposure of the latter event were larger than the former one, the policy implementation delay and the dependency of service areas in a single reservoir exposed the region to higher vulnerability. In addition to the structural and non-structural tools implemented just after the events, this work raises the possibility of rainwater reuse for reducing the stress in reservoirs.
KW  - droughts
KW  - urban water supply
KW  - water crisis
KW  - drought risk
KW  - paired event
KW  - analysis
KW  - vulnerability
Y1  - 2022
U6  - https://doi.org/10.1080/1573062X.2022.2047735
SN  - 1573-062X
SN  - 1744-9006
VL  - 20
IS  - 10
SP  - 1682
EP  - 1694
PB  - Taylor & Francis
CY  - London [u.a.]
ER  - 
TY  - JOUR
A1  - Gautam, Khem Raj
A1  - Zhang, Guoqiang
A1  - Landwehr, Niels
A1  - Adolphs, Julian
T1  - Machine learning for improvement of thermal conditions inside a hybrid ventilated animal building
JF  - Computers and electronics in agriculture : COMPAG online ; an international journal
N2  - In buildings with hybrid ventilation, natural ventilation opening positions (windows), mechanical ventilation rates, heating, and cooling are manipulated to maintain desired thermal conditions. The indoor temperature is regulated solely by ventilation (natural and mechanical) when the external conditions are favorable to save external heating and cooling energy. The ventilation parameters are determined by a rule-based control scheme, which is not optimal. This study proposes a methodology to enable real-time optimum control of ventilation parameters. We developed offline prediction models to estimate future thermal conditions from the data collected from building in operation. The developed offline model is then used to find the optimal controllable ventilation parameters in real-time to minimize the setpoint deviation in the building. With the proposed methodology, the experimental building's setpoint deviation improved for 87% of time, on average, by 0.53 degrees C compared to the current deviations.
KW  - Animal building
KW  - Natural ventilation
KW  - Automatically controlled windows
KW  - Machine learning
KW  - Optimization
Y1  - 2021
U6  - https://doi.org/10.1016/j.compag.2021.106259
SN  - 0168-1699
SN  - 1872-7107
VL  - 187
PB  - Elsevier Science
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Camargo, Tibor de
A1  - Schirrmann, Michael
A1  - Landwehr, Niels
A1  - Dammer, Karl-Heinz
A1  - Pflanz, Michael
T1  - Optimized deep learning model as a basis for fast UAV mapping of weed species in winter wheat crops
JF  - Remote sensing / Molecular Diversity Preservation International (MDPI)
N2  - Weed maps should be available quickly, reliably, and with high detail to be useful for site-specific management in crop protection and to promote more sustainable agriculture by reducing pesticide use. Here, the optimization of a deep residual convolutional neural network (ResNet-18) for the classification of weed and crop plants in UAV imagery is proposed. The target was to reach sufficient performance on an embedded system by maintaining the same features of the ResNet-18 model as a basis for fast UAV mapping. This would enable online recognition and subsequent mapping of weeds during UAV flying operation. Optimization was achieved mainly by avoiding redundant computations that arise when a classification model is applied on overlapping tiles in a larger input image. The model was trained and tested with imagery obtained from a UAV flight campaign at low altitude over a winter wheat field, and classification was performed on species level with the weed species Matricaria chamomilla L., Papaver rhoeas L., Veronica hederifolia L., and Viola arvensis ssp. arvensis observed in that field. The ResNet-18 model with the optimized image-level prediction pipeline reached a performance of 2.2 frames per second with an NVIDIA Jetson AGX Xavier on the full resolution UAV image, which would amount to about 1.78 ha h(-1) area output for continuous field mapping. The overall accuracy for determining crop, soil, and weed species was 94%. There were some limitations in the detection of species unknown to the model. When shifting from 16-bit to 32-bit model precision, no improvement in classification accuracy was observed, but a strong decline in speed performance, especially when a higher number of filters was used in the ResNet-18 model. Future work should be directed towards the integration of the mapping process on UAV platforms, guiding UAVs autonomously for mapping purpose, and ensuring the transferability of the models to other crop fields.
KW  - ResNet
KW  - deep residual networks
KW  - UAV imagery
KW  - embedded systems
KW  - crop
KW  - monitoring
KW  - image classification
KW  - site-specific weed management
KW  - real-time mapping
Y1  - 2021
U6  - https://doi.org/10.3390/rs13091704
SN  - 2072-4292
VL  - 13
IS  - 9
PB  - MDPI
CY  - Basel
ER  - 
TY  - GEN
A1  - Peng, Lei
A1  - Yarman, Aysu
A1  - Jetzschmann, Katharina J.
A1  - Jeoung, Jae-Hun
A1  - Schad, Daniel
A1  - Dobbek, Holger
A1  - Wollenberger, Ursula
A1  - Scheller, Frieder W.
T1  - Molecularly imprinted electropolymer for a hexameric heme protein with direct electron transfer and peroxide electrocatalysis
N2  - For the first time a molecularly imprinted polymer (MIP) with direct electron transfer (DET) and bioelectrocatalytic activity of the target protein is presented. Thin films of MIPs for the recognition of a hexameric tyrosine-coordinated heme protein (HTHP) have been prepared by electropolymerization of scopoletin after oriented assembly of HTHP on a self-assembled monolayer (SAM) of mercaptoundecanoic acid (MUA) on gold electrodes. Cavities which should resemble the shape and size of HTHP were formed by template removal. Rebinding of the target protein sums up the recognition by non-covalent interactions between the protein and the MIP with the electrostatic attraction of the protein by the SAM. HTHP bound to the MIP exhibits quasi-reversible DET which is reflected by a pair of well pronounced redox peaks in the cyclic voltammograms (CVs) with a formal potential of −184.4 ± 13.7 mV vs. Ag/AgCl (1 M KCl) at pH 8.0 and it was able to catalyze the cathodic reduction of peroxide. At saturation the MIP films show a 12-fold higher electroactive surface concentration of HTHP than the non-imprinted polymer (NIP).
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 362 
KW  - molecularly imprinted polymers
KW  - self-assembled monolayer
KW  - direct electron transfer
KW  - hydrogen peroxide
KW  - bioelectrocatalysis
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-400627
ER  - 
TY  - JOUR
A1  - Lass, Sander
T1  - ControlCenter 4.0
BT  - erleichterte Inbetriebnahme und Steuerung der Simulationsumgebung
JF  - Fabriksoftware : die digitale Fabrik realisieren
Y1  - 2021
SN  - 2569-7692
VL  - 26
IS  - 2
SP  - 30
EP  - 31
PB  - GITO mbH - Verlag für Industrielle Informationstechnik und Organisation
CY  - Berlin
ER  - 
TY  - GEN
A1  - Kar, Manaswita
A1  - Körzdörfer, Thomas
T1  - Computational high throughput screening of inorganic cation based halide perovskites for perovskite only tandem solar cells
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - We search for homovalent alternatives for A, B, and X-ions in ABX(3) type inorganic halide perovskites suitable for tandem solar cell applications. We replace the conventional A-site organic cation CH3NH3, by 3 inorganic cations, Cs, K, and Rb, and the B site consists of metals; Cd, Hg, Ge, Pb, and Sn This work is built on our previous high throughput screening of hybrid perovskite materials (Kar et al 2018 J. Chem. Phys. 149, 214701). By performing a systematic screening study using Density Functional Theory (DFT) methods, we found 11 suitable candidates; 2 Cs-based, 3 K-based and 6 Rb-based that are suitable for tandem solar cell applications.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1438 
KW  - inorganic perovskites
KW  - tandem solar cells
KW  - density functional theory
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-516831
SN  - 1866-8372
IS  - 5
ER  - 
TY  - CHAP
A1  - Grum, Marcus
A1  - Klippert, Monika
A1  - Albers, Albert
A1  - Gronau, Norbert
A1  - Thim, Christof
T1  - Examining the quality of knowledge transfers
BT  - the draft of an empirical research
T2  - Proceedings of the Design Society
N2  - Already successfully used products or designs, past projects or our own experiences can be the basis for the development of new products. As reference products or existing knowledge, it is reused in the development process and across generations of products. Since further, products are developed in cooperation, the development of new product generations is characterized by knowledge-intensive processes in which information and knowledge are exchanged between different kinds of knowledge carriers. The particular knowledge transfer here describes the identification of knowledge, its transmission from the knowledge carrier to the knowledge receiver, and its application by the knowledge receiver, which includes embodied knowledge of physical products. Initial empirical findings of the quantitative effects regarding the speed of knowledge transfers already have been examined. However, the factors influencing the quality of knowledge transfer to increase the efficiency and effectiveness of knowledge transfer in product development have not yet been examined empirically. Therefore, this paper prepares an experimental setting for the empirical investigation of the quality of knowledge transfers.
KW  - knowledge management
KW  - new product development
KW  - evaluation
Y1  - 2021
U6  - https://doi.org/10.1017/pds.2021.404
SN  - 2732-527X
VL  - 1
SP  - 1431
EP  - 1440
PB  - Cambridge University Press
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Melliger, Marc André
A1  - Lilliestam, Johan
T1  - Effects of coordinating support policy changes on renewable power investor choices in Europe
JF  - Energy policy : the international journal of the political, economic, planning, environmental and social aspects of energy
N2  - The economic context for renewable power in Europe is shifting: feed-in tariffs are replaced by auctioned premiums as the main support schemes. As renewables approach competitiveness, political pressure mounts to phase out support, whereas some other actors perceive a need for continued fixed-price support. We investigate how the phase-out of support or the reintroduction of feed-in tariffs would affect investors' choices for renewables through a conjoint analysis. In particular, we analyse the impact of coordination - the simultaneousness - of policy changes across countries and technologies. We find that investment choices are not strongly affected if policy changes are coordinated and returns unaffected. However, if policy changes are uncoordinated, investments shift to still supported - less mature and costlier - technologies or countries where support remains or is reintroduced. This shift is particularly strong for large investors and could potentially skew the European power mix towards an over-reliance on a single, less mature technology or specific generation region, resulting in a more expensive power system. If European countries want to change their renewable power support policies, and especially if they phase out support and expose renewables to market competition, it is important that they coordinate their actions.
KW  - Policy change
KW  - Policy coordination
KW  - Renewable energy
KW  - Investment
KW  - decision
KW  - Choice experiment
KW  - Adaptive conjoint analysis
Y1  - 2021
U6  - https://doi.org/10.1016/j.enpol.2020.111993
SN  - 0301-4215
VL  - 148
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - GEN
A1  - Morishita, Yu
A1  - Lazecky, Milan
A1  - Wright, Tim J.
A1  - Weiss, Jonathan R.
A1  - Elliott, John R.
A1  - Hooper, Andy
T1  - LiCSBAS
BT  - An Open-Source InSAR Time Series Analysis Package Integrated with the LiCSAR Automated Sentinel-1 InSAR Processor
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - For the past five years, the 2-satellite Sentinel-1 constellation has provided abundant and useful Synthetic Aperture Radar (SAR) data, which have the potential to reveal global ground surface deformation at high spatial and temporal resolutions. However, for most users, fully exploiting the large amount of associated data is challenging, especially over wide areas. To help address this challenge, we have developed LiCSBAS, an open-source SAR interferometry (InSAR) time series analysis package that integrates with the automated Sentinel-1 InSAR processor (LiCSAR). LiCSBAS utilizes freely available LiCSAR products, and users can save processing time and disk space while obtaining the results of InSAR time series analysis. In the LiCSBAS processing scheme, interferograms with many unwrapping errors are automatically identified by loop closure and removed. Reliable time series and velocities are derived with the aid of masking using several noise indices. The easy implementation of atmospheric corrections to reduce noise is achieved with the Generic Atmospheric Correction Online Service for InSAR (GACOS). Using case studies in southern Tohoku and the Echigo Plain, Japan, we demonstrate that LiCSBAS applied to LiCSAR products can detect both large-scale (>100 km) and localized (~km) relative displacements with an accuracy of <1 cm/epoch and ~2 mm/yr. We detect displacements with different temporal characteristics, including linear, periodic, and episodic, in Niigata, Ojiya, and Sanjo City, respectively. LiCSBAS and LiCSAR products facilitate greater exploitation of globally available and abundant SAR datasets and enhance their applications for scientific research and societal benefit.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1078 
KW  - InSAR
KW  - Sentinel-1
KW  - time series analysis
KW  - deformation monitoring
KW  - tectonics
KW  - subsidence
KW  - automatic processing
KW  - global
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-472431
SN  - 1866-8372
IS  - 1078
ER  - 
TY  - JOUR
A1  - Abramova, Olga
T1  - No matter what the name, we're all the same?
BT  - examining ethnic online discrimination in ridesharing marketplaces
JF  - Electronic markets
N2  - Sharing marketplaces emerged as the new Holy Grail of value creation by enabling exchanges between strangers. Identity reveal, encouraged by platforms, cuts both ways: While inducing pre-transaction confidence, it is suspected of backfiring on the information senders with its discriminative potential. This study employs a discrete choice experiment to explore the role of names as signifiers of discriminative peculiarities and the importance of accompanying cues in peer choices of a ridesharing offer. We quantify users' preferences for quality signals in monetary terms and evidence comparative disadvantage of Middle Eastern descent male names for drivers and co-travelers. It translates into a lower willingness to accept and pay for an offer. Market simulations confirm the robustness of the findings. Further, we discover that females are choosier and include more signifiers of involuntary personal attributes in their decision-making. Price discounts and positive information only partly compensate for the initial disadvantage, and identity concealment is perceived negatively.
KW  - sharing economy
KW  - discrimination
KW  - racism
KW  - discrete choice experiment
KW  - stated preferences
KW  - social inclusion
Y1  - 2022
U6  - https://doi.org/10.1007/s12525-021-00505-z
SN  - 1019-6781
SN  - 1422-8890
VL  - 32
SP  - 1419
EP  - 1446
PB  - Springer
CY  - Heidelberg
ER  -