TY - JOUR A1 - Zali, Zahra A1 - Ohrnberger, Matthias A1 - Scherbaum, Frank A1 - Cotton, Fabrice A1 - Eibl, Eva P. S. T1 - Volcanic tremor extraction and earthquake detection using music information retrieval algorithms JF - Seismological research letters N2 - Volcanic tremor signals are usually observed before or during volcanic eruptions and must be monitored to evaluate the volcanic activity. A challenge in studying seismic signals of volcanic origin is the coexistence of transient signal swarms and long-lasting volcanic tremor signals. Separating transient events from volcanic tremors can, therefore, contrib-ute to improving upon our understanding of the underlying physical processes. Exploiting the idea of harmonic-percussive separation in musical signal processing, we develop a method to extract the harmonic volcanic tremor signals and to detect tran-sient events from seismic recordings. Based on the similarity properties of spectrogram frames in the time-frequency domain, we decompose the signal into two separate spec-trograms representing repeating (harmonic) and nonrepeating (transient) patterns, which correspond to volcanic tremor signals and earthquake signals, respectively. We reconstruct the harmonic tremor signal in the time domain from the complex spectrogram of the repeating pattern by only considering the phase components for the frequency range in which the tremor amplitude spectrum is significantly contribut-ing to the energy of the signal. The reconstructed signal is, therefore, clean tremor signal without transient events. Furthermore, we derive a characteristic function suitable for the detection of tran-sient events (e.g., earthquakes) by integrating amplitudes of the nonrepeating spectro-gram over frequency at each time frame. Considering transient events like earthquakes, 78% of the events are detected for signal-to-noise ratio = 0.1 in our semisynthetic tests. In addition, we compared the number of detected earthquakes using our method for one month of continuous data recorded during the Holuhraun 2014-2015 eruption in Iceland with the bulletin presented in Agustsdottir et al. (2019). Our single station event detection algorithm identified 84% of the bulletin events. Moreover, we detected a total of 12,619 events, which is more than twice the number of the bulletin events. KW - algorithms KW - body waves KW - earthquakes KW - elastic waves KW - eruptions KW - geologic hazards KW - natural hazards KW - P-waves KW - S-waves KW - seismic waves KW - signal-to-noise ratio KW - swarms KW - volcanic earthquakes Y1 - 2021 U6 - https://doi.org/10.1785/0220210016 SN - 0895-0695 SN - 1938-2057 VL - 92 IS - 6 SP - 3668 EP - 3681 PB - Seismological Society of America CY - Boulder, Colo. ER - TY - JOUR A1 - Mischke, Dennis T1 - Deleuze and the digital BT - on the materiality of algorithmic infrastructures JF - Deleuze and Guattari studies N2 - In his short and often quoted essay 'Postscript on the Societies of Control', Gilles Deleuze famously describes the structures of power in the dawning twenty-first century as driven by 'machines of a third type, computers', as novel and predominantly digital infrastructures. In fact, from a Deleuzian perspective the entire ecosystem of the digital transformation can be described as a larger shift in modes of production and the political economy. This essay proposes to read this 'technological evolution' as the power of algorithms and their material substance - digital infrastructures that entail a different mode of interaction between humans and technology. In looking at these infrastructures from a materialist position, my essay reconceptualises the digital as the unfolding logic of assemblages that have been shaping a 'long now' of technological modernity. In bringing a Deleuzian reading of infrastructures to the study of technology and society, this essay seeks to shed a new light on the political function-and the increasing abstraction-of infrastructures in the realm of the digital. KW - digital materialism KW - critical infrastructure studies KW - culture and KW - algorithms KW - societies of control KW - abstract machines KW - assemblages Y1 - 2021 U6 - https://doi.org/10.3366/dlgs.2021.0459 SN - 2398-9777 SN - 2398-9785 VL - 15 IS - 4 SP - 593 EP - 609 PB - Edinburgh University Press CY - Edinburgh ER - TY - JOUR A1 - Casel, Katrin A1 - Dreier, Jan A1 - Fernau, Henning A1 - Gobbert, Moritz A1 - Kuinke, Philipp A1 - Villaamil, Fernando Sánchez A1 - Schmid, Markus L. A1 - van Leeuwen, Erik Jan T1 - Complexity of independency and cliquy trees JF - Discrete applied mathematics N2 - An independency (cliquy) tree of an n-vertex graph G is a spanning tree of G in which the set of leaves induces an independent set (clique). We study the problems of minimizing or maximizing the number of leaves of such trees, and fully characterize their parameterized complexity. We show that all four variants of deciding if an independency/cliquy tree with at least/most l leaves exists parameterized by l are either Para-NP- or W[1]-hard. We prove that minimizing the number of leaves of a cliquy tree parameterized by the number of internal vertices is Para-NP-hard too. However, we show that minimizing the number of leaves of an independency tree parameterized by the number k of internal vertices has an O*(4(k))-time algorithm and a 2k vertex kernel. Moreover, we prove that maximizing the number of leaves of an independency/cliquy tree parameterized by the number k of internal vertices both have an O*(18(k))-time algorithm and an O(k 2(k)) vertex kernel, but no polynomial kernel unless the polynomial hierarchy collapses to the third level. Finally, we present an O(3(n) . f(n))-time algorithm to find a spanning tree where the leaf set has a property that can be decided in f (n) time and has minimum or maximum size. KW - independency tree KW - cliquy tree KW - parameterized complexity KW - Kernelization KW - algorithms KW - exact algorithms Y1 - 2018 U6 - https://doi.org/10.1016/j.dam.2018.08.011 SN - 0166-218X SN - 1872-6771 VL - 272 SP - 2 EP - 15 PB - Elsevier CY - Amsterdam [u.a.] ER - TY - JOUR A1 - Klie, Sebastian A1 - Nikoloski, Zoran A1 - Selbig, Joachim T1 - Biological cluster evaluation for gene function prediction JF - Journal of computational biology N2 - Recent advances in high-throughput omics techniques render it possible to decode the function of genes by using the "guilt-by-association" principle on biologically meaningful clusters of gene expression data. However, the existing frameworks for biological evaluation of gene clusters are hindered by two bottleneck issues: (1) the choice for the number of clusters, and (2) the external measures which do not take in consideration the structure of the analyzed data and the ontology of the existing biological knowledge. Here, we address the identified bottlenecks by developing a novel framework that allows not only for biological evaluation of gene expression clusters based on existing structured knowledge, but also for prediction of putative gene functions. The proposed framework facilitates propagation of statistical significance at each of the following steps: (1) estimating the number of clusters, (2) evaluating the clusters in terms of novel external structural measures, (3) selecting an optimal clustering algorithm, and (4) predicting gene functions. The framework also includes a method for evaluation of gene clusters based on the structure of the employed ontology. Moreover, our method for obtaining a probabilistic range for the number of clusters is demonstrated valid on synthetic data and available gene expression profiles from Saccharomyces cerevisiae. Finally, we propose a network-based approach for gene function prediction which relies on the clustering of optimal score and the employed ontology. Our approach effectively predicts gene function on the Saccharomyces cerevisiae data set and is also employed to obtain putative gene functions for an Arabidopsis thaliana data set. KW - algorithms KW - biochemical networks KW - combinatorics KW - computational molecular biology KW - databases KW - functional genomics KW - gene expression KW - NP-completeness Y1 - 2014 U6 - https://doi.org/10.1089/cmb.2009.0129 SN - 1066-5277 SN - 1557-8666 VL - 21 IS - 6 SP - 428 EP - 445 PB - Liebert CY - New Rochelle ER - TY - JOUR A1 - Kreowsky, Philipp A1 - Stabernack, Christian Benno T1 - A full-featured FPGA-based pipelined architecture for SIFT extraction JF - IEEE access : practical research, open solutions / Institute of Electrical and Electronics Engineers N2 - Image feature detection is a key task in computer vision. Scale Invariant Feature Transform (SIFT) is a prevalent and well known algorithm for robust feature detection. However, it is computationally demanding and software implementations are not applicable for real-time performance. In this paper, a versatile and pipelined hardware implementation is proposed, that is capable of computing keypoints and rotation invariant descriptors on-chip. All computations are performed in single precision floating-point format which makes it possible to implement the original algorithm with little alteration. Various rotation resolutions and filter kernel sizes are supported for images of any resolution up to ultra-high definition. For full high definition images, 84 fps can be processed. Ultra high definition images can be processed at 21 fps. KW - Field programmable gate arrays KW - Convolution KW - Signal processing KW - algorithms KW - Kernel KW - Image resolution KW - Histograms KW - Feature extraction KW - Scale-invariant feature transform (SIFT) KW - field-programmable gate array KW - (FPGA) KW - image processing KW - computer vision KW - parallel processing KW - architecture KW - real-time KW - hardware architecture Y1 - 2021 U6 - https://doi.org/10.1109/ACCESS.2021.3104387 SN - 2169-3536 VL - 9 SP - 128564 EP - 128573 PB - Inst. of Electr. and Electronics Engineers CY - New York, NY ER -