@article{BleifussBornemannJohnsonetal.2018, author = {Bleifuss, Tobias and Bornemann, Leon and Johnson, Theodore and Kalashnikov, Dmitri and Naumann, Felix and Srivastava, Divesh}, title = {Exploring Change}, series = {Proceedings of the VLDB Endowment}, volume = {12}, journal = {Proceedings of the VLDB Endowment}, number = {2}, publisher = {Association for Computing Machinery}, address = {New York}, issn = {2150-8097}, doi = {10.14778/3282495.3282496}, pages = {85 -- 98}, year = {2018}, abstract = {Data and metadata in datasets experience many different kinds of change. Values axe inserted, deleted or updated; rows appear and disappear; columns are added or repurposed, etc. In such a dynamic situation, users might have many questions related to changes in the dataset, for instance which parts of the data are trustworthy and which are not? Users will wonder: How many changes have there been in the recent minutes, days or years? What kind of changes were made at which points of time? How dirty is the data? Is data cleansing required? The fact that data changed can hint at different hidden processes or agendas: a frequently crowd-updated city name may be controversial; a person whose name has been recently changed may be the target of vandalism; and so on. We show various use cases that benefit from recognizing and exploring such change. We envision a system and methods to interactively explore such change, addressing the variability dimension of big data challenges. To this end, we propose a model to capture change and the process of exploring dynamic data to identify salient changes. We provide exploration primitives along with motivational examples and measures for the volatility of data. We identify technical challenges that need to be addressed to make our vision a reality, and propose directions of future work for the data management community.}, language = {en} } @article{MaximovaGieseKrause2018, author = {Maximova, Maria and Giese, Holger and Krause, Christian}, title = {Probabilistic timed graph transformation systems}, series = {Journal of Logical and Algebraic Methods in Programming}, volume = {101}, journal = {Journal of Logical and Algebraic Methods in Programming}, publisher = {Elsevier}, address = {New York}, issn = {2352-2208}, doi = {10.1016/j.jlamp.2018.09.003}, pages = {110 -- 131}, year = {2018}, abstract = {Today, software has become an intrinsic part of complex distributed embedded real-time systems. The next generation of embedded real-time systems will interconnect the today unconnected systems via complex software parts and the service-oriented paradigm. Due to these interconnections, the architecture of systems can be subject to changes at run-time, e.g. when dynamic binding of service end-points is employed or complex collaborations are established dynamically. However, suitable formalisms and techniques that allow for modeling and analysis of timed and probabilistic behavior of such systems as well as of their structure dynamics do not exist so far. To fill the identified gap, we propose Probabilistic Timed Graph Transformation Systems (PTGTSs) as a high-level description language that supports all the necessary aspects of structure dynamics, timed behavior, and probabilistic behavior. We introduce the formal model of PTGTSs in this paper as well as present and formally verify a mapping of models with finite state spaces to probabilistic timed automata (PTA) that allows to use the PRISM model checker to analyze PTGTS models with respect to PTCTL properties. (C) 2018 Elsevier Inc. All rights reserved.}, language = {en} } @misc{BjoerkHoelzle2018, author = {Bj{\"o}rk, Jennie and H{\"o}lzle, Katharina}, title = {Editorial}, series = {Creativity and innovation management}, volume = {27}, journal = {Creativity and innovation management}, number = {4}, publisher = {Wiley}, address = {Hoboken}, issn = {0963-1690}, doi = {10.1111/caim.12298}, pages = {373 -- 374}, year = {2018}, abstract = {"Never doubt that a small group of thoughtful, committed citizens can change the world; indeed, it's the only thing that ever has. - Margaret Mead." With the last issue of this year we want to point out directions towards what will come and what challenges and opportunities lie ahead of us. More needed than ever are joint creative efforts to find ways to collaborate and innovate in order to secure the wellbeing of our earth for the next generation to come. We have found ourselves puzzled that we could assemble a sustainability issue without having a call for papers or a special issue. In fact, many of the submissions we currently receive, deal with sustainable, ecological or novel approaches to management and organizations. As creativity and innovation are undisputable necessary ingredients for reaching the sustainable development goals, empirical proof and research in this area are still in their infancy. While the role of design and design thinking has been highlighted before for solving wicked societal problems, a lot more research is needed which creative and innovative ways organisations and societies can take to find solutions to climate change, poverty, hunger and education. We would therefore like to call to you, our readers and writers to tackle these problems with your research. The first article in this issue addresses one of the above named challenges - the role of innovation for achieving the transition to a low-carbon energy world. In "Innovating for low-carbon energy through hydropower: Enabling a conservation charity's transition to a low-carbon community", the authors John Gallagher, Paul Coughlan, A. Prysor Williams and Aonghus McNabola look at how an eco-design approach has supported a community transition to low-carbon. They highlight the importance of effective management as well as external collaboration and how the key for success lay in fostering an open environment for creativity and idea sharing. The second article addresses another of the grand challenges, the future of mobility and uses a design-driven approach to develop scenarios for mobility in cities. In "Designing radical innovations of meanings for society: envisioning new scenarios for smart mobility", the authors Claudio Dell'Era, Naiara Altuna and Roberto Verganti investigate how new meanings can be designed and proposed to society rather than to individuals in the particular context of smart mobility. Through two case studies the authors argue for a multi-level perspective, taking the perspective of the society to solve societal challenges while considering the needs of the individual. The latter is needed because we will not change if our needs are not addressed. Furthermore, the authors find that both, meaning and technology need to be considered to create radical innovation for society. The role of meaning continues in the third article in this issue. The authors Marta Gasparin and William Green show in their article "Reconstructing meaning without redesigning products: The case of the Serie7 chair" how meaning changes over time even though the product remains the same. Through an in-depth retrospective study of the Serie 7 chair the authors investigate the relationship between meaning and the materiality of the object, and show the importance of materiality in constructing product meaning over long periods. Translating this meaning over the course of the innovation process is an important task of management in order to gain buy-in from all involved stakeholders. In the following article "A systematic approach for new technology development by using a biomimicry-based TRIZ contradiction matrix" the authors Byungun Yoon, Chaeguk Lim, Inchae Park and Dooseob Yoon develop a systematic process combining biomimicry and technology-based TRIZ in order to solve technological problems or develop new technologies based on completely new sources or combinations from technology and biology. In the fifth article in this issue "Innovating via Building Absorptive Capacity: Interactive Effects of Top Management Support of Learning, Employee Learning Orientation, and Decentralization Structure" the authors Li-Yun Sun, Chenwei Li and Yuntao Dong examine the effect of learning-related personal and contextual factors on organizational absorptive capability and subsequent innovative performance. The authors find positive effects as well as a moderation influence of decentralized organizational decision-making structures. In the sixth article "Creativity within boundaries: social identity and the development of new ideas in franchise systems" the authors Fanny Simon, Catherine Allix-Desfautaux, Nabil Khelil and Anne-Laure Le Nadant address the paradox of balancing novelty and conformity for creativity in a franchise system. This research is one of the first we know to explicitly address creativity and innovation in such a rigid and pre-determined system. Using a social identity perspective, they can show that social control, which may be exerted by manipulating group identity, is an efficient lever to increase both the creation and the diffusion of the idea. Furthermore, they show that franchisees who do not conform to the norm of the group are stigmatized and must face pressure from the group to adapt their behaviors. This has important implications for future research. In the following article "Exploring employee interactions and quality of contributions in intra-organisational innovation platforms" the authors Dimitra Chasanidou, Nj{\aa}l Sivertstol and Jarle Hildrum examine the user interactions in an intra-organisational innovation platform, and also address the influence of user interactions for idea development. The authors find that employees communicate through the innovation platform with different interaction, contribution and collaboration types and propose three types of contribution qualities—passive, efficient and balanced contribution. In the eighth article "Ready for Take-off": How Open Innovation influences startup success" Cristina Marullo, Elena Casprini, Alberto di Minin and Andrea Piccaluga seek to predict new venture success based on factors that can be observed in the pre-startup phase. The authors introduce different variables of founding teams and how these relate to startup success. Building on large-scale dataset of submitted business plans at UC Berkeley, they can show that teams with high skills diversity and past joint experience are a lot better able to prevent the risk of business failure at entry and to adapt the internal resources to market conditions. Furthermore, it is crucial for the team to integrate many external knowledge sources into their process (openness) in order to be successful. The crucial role of knowledge and how it is communicated and shared is the focal point of Natalya Sergeeva's and Anna Trifilova's article on "The role of storytelling in the innovation process". They authors can show how storytelling has an important role to play when it comes to motivating employees to innovate and promoting innovation success stories inside and outside the organization. The deep human desire to hear and experience stories is also addressed in the last article in this issue "Gamification Approaches to the Early Stage of Innovation" by Rui Patricio, Antonio Moreira and Francesco Zurlo. Using gamification approaches at the early stage of innovation promises to create better team coherence, let employees experience fun and engagement, improve communication and foster knowledge exchange. Using an analytical framework, the authors analyze 15 articles that have looked at gamification in the context of innovation management before. They find that gamification indeed supports firms in becoming better at performing complex innovation tasks and managing innovation challenges. Furthermore, gamification in innovation creates a space for inspiration, improves creativity and the generation of high potential ideas.}, language = {en} } @article{OrejasPinoNavarroetal.2018, author = {Orejas, Fernando and Pino, Elvira and Navarro, Marisa and Lambers, Leen}, title = {Institutions for navigational logics for graphical structures}, series = {Theoretical computer science}, volume = {741}, journal = {Theoretical computer science}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0304-3975}, doi = {10.1016/j.tcs.2018.02.031}, pages = {19 -- 24}, year = {2018}, abstract = {We show that a Navigational Logic, i.e., a logic to express properties about graphs and about paths in graphs is a semi-exact institution. In this way, we can use a number of operations to structure and modularize our specifications. Moreover, using the properties of our institution, we also show how to structure single formulas, which in our formalism could be quite complex.}, language = {en} } @article{BertiEquilleHarmouchNaumannetal.2018, author = {Berti-Equille, Laure and Harmouch, Nazar and Naumann, Felix and Novelli, Noel and Saravanan, Thirumuruganathan}, title = {Discovery of genuine functional dependencies from relational data with missing values}, series = {Proceedings of the VLDB Endowment}, volume = {11}, journal = {Proceedings of the VLDB Endowment}, number = {8}, publisher = {Association for Computing Machinery}, address = {New York}, issn = {2150-8097}, doi = {10.14778/3204028.3204032}, pages = {880 -- 892}, year = {2018}, abstract = {Functional dependencies (FDs) play an important role in maintaining data quality. They can be used to enforce data consistency and to guide repairs over a database. In this work, we investigate the problem of missing values and its impact on FD discovery. When using existing FD discovery algorithms, some genuine FDs could not be detected precisely due to missing values or some non-genuine FDs can be discovered even though they are caused by missing values with a certain NULL semantics. We define a notion of genuineness and propose algorithms to compute the genuineness score of a discovered FD. This can be used to identify the genuine FDs among the set of all valid dependencies that hold on the data. We evaluate the quality of our method over various real-world and semi-synthetic datasets with extensive experiments. The results show that our method performs well for relatively large FD sets and is able to accurately capture genuine FDs.}, language = {en} } @misc{HorowitzFeiRamosetal.2018, author = {Horowitz, Carol R. and Fei, Kezhen and Ramos, Michelle A. and Hauser, Diane and Ellis, Stephen B. and Calman, Neil and B{\"o}ttinger, Erwin}, title = {Receipt of genetic risk information significantly improves blood pressure control among African anecestry adults with hypertension}, series = {Journal of General Internal Medicine}, volume = {33}, journal = {Journal of General Internal Medicine}, publisher = {Springer}, address = {New York}, issn = {0884-8734}, doi = {10.1007/s11606-018-4413-y}, pages = {S322 -- S323}, year = {2018}, language = {en} } @misc{AlvianoRomeroDavilaSchaub2018, author = {Alviano, Mario and Romero Davila, Javier and Schaub, Torsten H.}, title = {Preference Relations by Approximation}, series = {Sixteenth International Conference on Principles of Knowledge Representation and Reasoning}, journal = {Sixteenth International Conference on Principles of Knowledge Representation and Reasoning}, publisher = {AAAI Conference on Artificial Intelligence}, address = {Palo Alto}, pages = {2 -- 11}, year = {2018}, abstract = {Declarative languages for knowledge representation and reasoning provide constructs to define preference relations over the set of possible interpretations, so that preferred models represent optimal solutions of the encoded problem. We introduce the notion of approximation for replacing preference relations with stronger preference relations, that is, relations comparing more pairs of interpretations. Our aim is to accelerate the computation of a non-empty subset of the optimal solutions by means of highly specialized algorithms. We implement our approach in Answer Set Programming (ASP), where problems involving quantitative and qualitative preference relations can be addressed by ASPRIN, implementing a generic optimization algorithm. Unlike this, chains of approximations allow us to reduce several preference relations to the preference relations associated with ASP's native weak constraints and heuristic directives. In this way, ASPRIN can now take advantage of several highly optimized algorithms implemented by ASP solvers for computing optimal solutions}, language = {en} } @misc{RischKrestel2018, author = {Risch, Julian and Krestel, Ralf}, title = {My Approach = Your Apparatus?}, series = {Libraries}, journal = {Libraries}, publisher = {Association for Computing Machinery}, address = {New York}, isbn = {978-1-4503-5178-2}, issn = {2575-7865}, doi = {10.1145/3197026.3197038}, pages = {283 -- 292}, year = {2018}, abstract = {Comparative text mining extends from genre analysis and political bias detection to the revelation of cultural and geographic differences, through to the search for prior art across patents and scientific papers. These applications use cross-collection topic modeling for the exploration, clustering, and comparison of large sets of documents, such as digital libraries. However, topic modeling on documents from different collections is challenging because of domain-specific vocabulary. We present a cross-collection topic model combined with automatic domain term extraction and phrase segmentation. This model distinguishes collection-specific and collection-independent words based on information entropy and reveals commonalities and differences of multiple text collections. We evaluate our model on patents, scientific papers, newspaper articles, forum posts, and Wikipedia articles. In comparison to state-of-the-art cross-collection topic modeling, our model achieves up to 13\% higher topic coherence, up to 4\% lower perplexity, and up to 31\% higher document classification accuracy. More importantly, our approach is the first topic model that ensures disjunct general and specific word distributions, resulting in clear-cut topic representations.}, language = {en} } @misc{FrickeDoellnerAsche2018, author = {Fricke, Andreas and D{\"o}llner, J{\"u}rgen Roland Friedrich and Asche, Hartmut}, title = {Servicification - Trend or Paradigm Shift in Geospatial Data Processing?}, series = {Computational Science and Its Applications - ICCSA 2018, PT III}, volume = {10962}, journal = {Computational Science and Its Applications - ICCSA 2018, PT III}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-95168-3}, issn = {0302-9743}, doi = {10.1007/978-3-319-95168-3_23}, pages = {339 -- 350}, year = {2018}, abstract = {Currently we are witnessing profound changes in the geospatial domain. Driven by recent ICT developments, such as web services, serviceoriented computing or open-source software, an explosion of geodata and geospatial applications or rapidly growing communities of non-specialist users, the crucial issue is the provision and integration of geospatial intelligence in these rapidly changing, heterogeneous developments. This paper introduces the concept of Servicification into geospatial data processing. Its core idea is the provision of expertise through a flexible number of web-based software service modules. Selection and linkage of these services to user profiles, application tasks, data resources, or additional software allow for the compilation of flexible, time-sensitive geospatial data handling processes. Encapsulated in a string of discrete services, the approach presented here aims to provide non-specialist users with geospatial expertise required for the effective, professional solution of a defined application problem. Providing users with geospatial intelligence in the form of web-based, modular services, is a completely different approach to geospatial data processing. This novel concept puts geospatial intelligence, made available through services encapsulating rule bases and algorithms, in the centre and at the disposal of the users, regardless of their expertise.}, language = {en} } @misc{ReimannKlingbeilPasewaldtetal.2018, author = {Reimann, Max and Klingbeil, Mandy and Pasewaldt, Sebastian and Semmo, Amir and Trapp, Matthias and D{\"o}llner, J{\"u}rgen Roland Friedrich}, title = {MaeSTrO: A Mobile App for Style Transfer Orchestration using Neural Networks}, series = {International Conference on Cyberworlds (CW)}, journal = {International Conference on Cyberworlds (CW)}, editor = {Sourin, A Sourina}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-7315-7}, doi = {10.1109/CW.2018.00016}, pages = {9 -- 16}, year = {2018}, abstract = {Mobile expressive rendering gained increasing popularity among users seeking casual creativity by image stylization and supports the development of mobile artists as a new user group. In particular, neural style transfer has advanced as a core technology to emulate characteristics of manifold artistic styles. However, when it comes to creative expression, the technology still faces inherent limitations in providing low-level controls for localized image stylization. This work enhances state-of-the-art neural style transfer techniques by a generalized user interface with interactive tools to facilitate a creative and localized editing process. Thereby, we first propose a problem characterization representing trade-offs between visual quality, run-time performance, and user control. We then present MaeSTrO, a mobile app for orchestration of neural style transfer techniques using iterative, multi-style generative and adaptive neural networks that can be locally controlled by on-screen painting metaphors. At this, first user tests indicate different levels of satisfaction for the implemented techniques and interaction design.}, language = {en} } @misc{LimbergerGroplerBuschmannetal.2018, author = {Limberger, Daniel and Gropler, Anne and Buschmann, Stefan and D{\"o}llner, J{\"u}rgen Roland Friedrich and Wasty, Benjamin}, title = {OpenLL}, series = {22nd International Conference Information Visualisation (IV)}, journal = {22nd International Conference Information Visualisation (IV)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-7202-0}, doi = {10.1109/iV.2018.00039}, pages = {175 -- 181}, year = {2018}, abstract = {Today's rendering APIs lack robust functionality and capabilities for dynamic, real-time text rendering and labeling, which represent key requirements for 3D application design in many fields. As a consequence, most rendering systems are barely or not at all equipped with respective capabilities. This paper drafts the unified text rendering and labeling API OpenLL intended to complement common rendering APIs, frameworks, and transmission formats. For it, various uses of static and dynamic placement of labels are showcased and a text interaction technique is presented. Furthermore, API design constraints with respect to state-of-the-art text rendering techniques are discussed. This contribution is intended to initiate a community-driven specification of a free and open label library.}, language = {en} } @article{VollmerTrappSchumannetal.2018, author = {Vollmer, Jan Ole and Trapp, Matthias and Schumann, Heidrun and D{\"o}llner, J{\"u}rgen Roland Friedrich}, title = {Hierarchical spatial aggregation for level-of-detail visualization of 3D thematic data}, series = {ACM transactions on spatial algorithms and systems}, volume = {4}, journal = {ACM transactions on spatial algorithms and systems}, number = {3}, publisher = {Association for Computing Machinery}, address = {New York}, issn = {2374-0353}, doi = {10.1145/3234506}, pages = {23}, year = {2018}, abstract = {Thematic maps are a common tool to visualize semantic data with a spatial reference. Combining thematic data with a geometric representation of their natural reference frame aids the viewer's ability in gaining an overview, as well as perceiving patterns with respect to location; however, as the amount of data for visualization continues to increase, problems such as information overload and visual clutter impede perception, requiring data aggregation and level-of-detail visualization techniques. While existing aggregation techniques for thematic data operate in a 2D reference frame (i.e., map), we present two aggregation techniques for 3D spatial and spatiotemporal data mapped onto virtual city models that hierarchically aggregate thematic data in real time during rendering to support on-the-fly and on-demand level-of-detail generation. An object-based technique performs aggregation based on scene-specific objects and their hierarchy to facilitate per-object analysis, while the scene-based technique aggregates data solely based on spatial locations, thus supporting visual analysis of data with arbitrary reference geometry. Both techniques can apply different aggregation functions (mean, minimum, and maximum) for ordinal, interval, and ratio-scaled data and can be easily extended with additional functions. Our implementation utilizes the programmable graphics pipeline and requires suitably encoded data, i.e., textures or vertex attributes. We demonstrate the application of both techniques using real-world datasets, including solar potential analyses and the propagation of pressure waves in a virtual city model.}, language = {en} } @misc{KoetzingKrejca2018, author = {K{\"o}tzing, Timo and Krejca, Martin Stefan}, title = {First-Hitting times under additive drift}, series = {Parallel Problem Solving from Nature - PPSN XV, PT II}, volume = {11102}, journal = {Parallel Problem Solving from Nature - PPSN XV, PT II}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-99259-4}, issn = {0302-9743}, doi = {10.1007/978-3-319-99259-4_8}, pages = {92 -- 104}, year = {2018}, abstract = {For the last ten years, almost every theoretical result concerning the expected run time of a randomized search heuristic used drift theory, making it the arguably most important tool in this domain. Its success is due to its ease of use and its powerful result: drift theory allows the user to derive bounds on the expected first-hitting time of a random process by bounding expected local changes of the process - the drift. This is usually far easier than bounding the expected first-hitting time directly. Due to the widespread use of drift theory, it is of utmost importance to have the best drift theorems possible. We improve the fundamental additive, multiplicative, and variable drift theorems by stating them in a form as general as possible and providing examples of why the restrictions we keep are still necessary. Our additive drift theorem for upper bounds only requires the process to be nonnegative, that is, we remove unnecessary restrictions like a finite, discrete, or bounded search space. As corollaries, the same is true for our upper bounds in the case of variable and multiplicative drift.}, language = {en} } @misc{KoetzingKrejca2018, author = {K{\"o}tzing, Timo and Krejca, Martin Stefan}, title = {First-Hitting times for finite state spaces}, series = {Parallel Problem Solving from Nature - PPSN XV, PT II}, volume = {11102}, journal = {Parallel Problem Solving from Nature - PPSN XV, PT II}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-99259-4}, issn = {0302-9743}, doi = {10.1007/978-3-319-99259-4_7}, pages = {79 -- 91}, year = {2018}, abstract = {One of the most important aspects of a randomized algorithm is bounding its expected run time on various problems. Formally speaking, this means bounding the expected first-hitting time of a random process. The two arguably most popular tools to do so are the fitness level method and drift theory. The fitness level method considers arbitrary transition probabilities but only allows the process to move toward the goal. On the other hand, drift theory allows the process to move into any direction as long as it move closer to the goal in expectation; however, this tendency has to be monotone and, thus, the transition probabilities cannot be arbitrary. We provide a result that combines the benefit of these two approaches: our result gives a lower and an upper bound for the expected first-hitting time of a random process over {0,..., n} that is allowed to move forward and backward by 1 and can use arbitrary transition probabilities. In case that the transition probabilities are known, our bounds coincide and yield the exact value of the expected first-hitting time. Further, we also state the stationary distribution as well as the mixing time of a special case of our scenario.}, language = {en} } @misc{KoetzingLagodzinskiLengleretal.2018, author = {K{\"o}tzing, Timo and Lagodzinski, Gregor J. A. and Lengler, Johannes and Melnichenko, Anna}, title = {Destructiveness of Lexicographic Parsimony Pressure and Alleviation by a Concatenation Crossover in Genetic Programming}, series = {Parallel Problem Solving from Nature - PPSN XV}, volume = {11102}, journal = {Parallel Problem Solving from Nature - PPSN XV}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-99259-4}, issn = {0302-9743}, doi = {10.1007/978-3-319-99259-4_4}, pages = {42 -- 54}, year = {2018}, abstract = {For theoretical analyses there are two specifics distinguishing GP from many other areas of evolutionary computation. First, the variable size representations, in particular yielding a possible bloat (i.e. the growth of individuals with redundant parts). Second, the role and realization of crossover, which is particularly central in GP due to the tree-based representation. Whereas some theoretical work on GP has studied the effects of bloat, crossover had a surprisingly little share in this work. We analyze a simple crossover operator in combination with local search, where a preference for small solutions minimizes bloat (lexicographic parsimony pressure); the resulting algorithm is denoted Concatenation Crossover GP. For this purpose three variants of the wellstudied Majority test function with large plateaus are considered. We show that the Concatenation Crossover GP can efficiently optimize these test functions, while local search cannot be efficient for all three variants independent of employing bloat control.}, language = {en} } @article{BobdaYongaGebseretal.2018, author = {Bobda, Christophe and Yonga, Franck and Gebser, Martin and Ishebabi, Harold and Schaub, Torsten H.}, title = {High-level synthesis of on-chip multiprocessor architectures based on answer set programming}, series = {Journal of Parallel and Distributed Computing}, volume = {117}, journal = {Journal of Parallel and Distributed Computing}, publisher = {Elsevier}, address = {San Diego}, issn = {0743-7315}, doi = {10.1016/j.jpdc.2018.02.010}, pages = {161 -- 179}, year = {2018}, abstract = {We present a system-level synthesis approach for heterogeneous multi-processor on chip, based on Answer Set Programming(ASP). Starting with a high-level description of an application, its timing constraints and the physical constraints of the target device, our goal is to produce the optimal computing infrastructure made of heterogeneous processors, peripherals, memories and communication components. Optimization aims at maximizing speed, while minimizing chip area. Also, a scheduler must be produced that fulfills the real-time requirements of the application. Even though our approach will work for application specific integrated circuits, we have chosen FPGA as target device in this work because of their reconfiguration capabilities which makes it possible to explore several design alternatives. This paper addresses the bottleneck of problem representation size by providing a direct and compact ASP encoding for automatic synthesis that is semantically equivalent to previously established ILP and ASP models. We describe a use-case in which designers specify their applications in C/C++ from which optimum systems can be derived. We demonstrate the superiority of our approach toward existing heuristics and exact methods with synthesis results on a set of realistic case studies. (C) 2018 Elsevier Inc. All rights reserved.}, language = {en} } @article{MenningGrasnickEwaldetal.2018, author = {Menning, Axel and Grasnick, Bastien M. and Ewald, Benedikt and Dobrigkeit, Franziska and Nicolai, Claudia}, title = {Verbal focus shifts}, series = {Design Studies}, volume = {57}, journal = {Design Studies}, publisher = {Elsevier}, address = {Oxford}, issn = {0142-694X}, doi = {10.1016/j.destud.2018.03.003}, pages = {135 -- 155}, year = {2018}, abstract = {Previous studies on design behaviour indicate that focus shifts positively influence ideational productivity. In this study we want to take a closer look at how these focus shifts look on the verbal level. We describe a mutually influencing relationship between mental focus shifts and verbal low coherent statements. In a case study based on the DTRS11 dataset we identify 297 low coherent statements via a combined topic modelling and manual approach. We introduce a categorization of the different instances of low coherent statements. The results indicate that designers tend to shift topics within an existing design issue instead of completely disrupting it. (C) 2018 Elsevier Ltd. All rights reserved.}, language = {en} } @article{YousfiHeweltBaueretal.2018, author = {Yousfi, Alaaeddine and Hewelt, Marcin and Bauer, Christine and Weske, Mathias}, title = {Toward uBPMN-Based patterns for modeling ubiquitous business processes}, series = {IEEE Transactions on Industrial Informatics}, volume = {14}, journal = {IEEE Transactions on Industrial Informatics}, number = {8}, publisher = {Inst. of Electr. and Electronics Engineers}, address = {Piscataway}, issn = {1551-3203}, doi = {10.1109/TII.2017.2777847}, pages = {3358 -- 3367}, year = {2018}, abstract = {Ubiquitous business processes are the new generation of processes that pervade the physical space and interact with their environments using a minimum of human involvement. Although they are now widely deployed in the industry, their deployment is still ad hoc . They are implemented after an arbitrary modeling phase or no modeling phase at all. The absence of a solid modeling phase backing up the implementation generates many loopholes that are stressed in the literature. Here, we tackle the issue of modeling ubiquitous business processes. We propose patterns to represent the recent ubiquitous computing features. These patterns are the outcome of an analysis we conducted in the field of human-computer interaction to examine how the features are actually deployed. The patterns' understandability, ease-of-use, usefulness, and completeness are examined via a user experiment. The results indicate that these four indexes are on the positive track. Hence, the patterns may be the backbone of ubiquitous business process modeling in industrial applications.}, language = {en} } @misc{DiazMendezSchoelzel2018, author = {Diaz, Sergio and Mendez, Diego and Sch{\"o}lzel, Mario}, title = {Dynamic Gallager-Humblet-Spira Algorithm for Wireless Sensor Networks}, series = {2018 IEEE Colombian Conference on Communications and Computing (COLCOM)}, journal = {2018 IEEE Colombian Conference on Communications and Computing (COLCOM)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-6820-7}, pages = {6}, year = {2018}, abstract = {The problem of constructing and maintaining a tree topology in a distributed manner is a challenging task in WSNs. This is because the nodes have limited computational and memory resources and the network changes over time. We propose the Dynamic Gallager-Humblet-Spira (D-GHS) algorithm that builds and maintains a minimum spanning tree. To do so, we divide D-GHS into four phases, namely neighbor discovery, tree construction, data collection, and tree maintenance. In the neighbor discovery phase, the nodes collect information about their neighbors and the link quality. In the tree construction, D-GHS finds the minimum spanning tree by executing the Gallager-Humblet-Spira algorithm. In the data collection phase, the sink roots the minimum spanning tree at itself, and each node sends data packets. In the tree maintenance phase, the nodes repair the tree when communication failures occur. The emulation results show that D-GHS reduces the number of control messages and the energy consumption, at the cost of a slight increase in memory size and convergence time.}, language = {en} } @misc{BoissierKurzynski2018, author = {Boissier, Martin and Kurzynski, Daniel}, title = {Workload-Driven Horizontal Partitioning and Pruning for Large HTAP Systems}, series = {2018 IEEE 34th International Conference on Data Engineering Workshops (ICDEW)}, journal = {2018 IEEE 34th International Conference on Data Engineering Workshops (ICDEW)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-6306-6}, doi = {10.1109/ICDEW.2018.00026}, pages = {116 -- 121}, year = {2018}, abstract = {Modern server systems with large NUMA architectures necessitate (i) data being distributed over the available computing nodes and (ii) NUMA-aware query processing to enable effective parallel processing in database systems. As these architectures incur significant latency and throughout penalties for accessing non-local data, queries should be executed as close as possible to the data. To further increase both performance and efficiency, data that is not relevant for the query result should be skipped as early as possible. One way to achieve this goal is horizontal partitioning to improve static partition pruning. As part of our ongoing work on workload-driven partitioning, we have implemented a recent approach called aggressive data skipping and extended it to handle both analytical as well as transactional access patterns. In this paper, we evaluate this approach with the workload and data of a production enterprise system of a Global 2000 company. The results show that over 80\% of all tuples can be skipped in average while the resulting partitioning schemata are surprisingly stable over time.}, language = {en} } @misc{PatalasMaliszewskaKrebs2018, author = {Patalas-Maliszewska, Justyna and Krebs, Irene}, title = {An Information System Supporting the Eliciting of Expert Knowledge for Successful IT Projects}, series = {Information and Software Technologies, ICIST 2018}, volume = {920}, journal = {Information and Software Technologies, ICIST 2018}, publisher = {Springer}, address = {Berlin}, isbn = {978-3-319-99972-2}, issn = {1865-0929}, doi = {10.1007/978-3-319-99972-2_1}, pages = {3 -- 13}, year = {2018}, abstract = {In order to guarantee the success of an IT project, it is necessary for a company to possess expert knowledge. The difficulty arises when experts no longer work for the company and it then becomes necessary to use their knowledge, in order to realise an IT project. In this paper, the ExKnowIT information system which supports the eliciting of expert knowledge for successful IT projects, is presented and consists of the following modules: (1) the identification of experts for successful IT projects, (2) the eliciting of expert knowledge on completed IT projects, (3) the expert knowledge base on completed IT projects, (4) the Group Method for Data Handling (GMDH) algorithm, (5) new knowledge in support of decisions regarding the selection of a manager for a new IT project. The added value of our system is that these three approaches, namely, the elicitation of expert knowledge, the success of an IT project and the discovery of new knowledge, gleaned from the expert knowledge base, otherwise known as the decision model, complement each other.}, language = {en} } @misc{IonBaudisch2018, author = {Ion, Alexandra and Baudisch, Patrick Markus}, title = {Metamaterial Devices}, publisher = {Association for Computing Machinery}, address = {New York}, isbn = {978-1-4503-5819-4}, doi = {10.1145/3214822.3214827}, pages = {2}, year = {2018}, abstract = {In our hands-on demonstration, we show several objects, the functionality of which is defined by the objects' internal micro-structure. Such metamaterial machines can (1) be mechanisms based on their microstructures, (2) employ simple mechanical computation, or (3) change their outside to interact with their environment. They are 3D printed from one piece and we support their creating by providing interactive software tools.}, language = {en} } @misc{BazhenovaZerbatoWeske2018, author = {Bazhenova, Ekaterina and Zerbato, Francesca and Weske, Mathias}, title = {Data-Centric Extraction of DMN Decision Models from BPMN Process Models}, series = {Business Process Management Workshops}, volume = {308}, journal = {Business Process Management Workshops}, publisher = {Springer}, address = {Berlin}, isbn = {978-3-319-74030-0}, issn = {1865-1348}, doi = {10.1007/978-3-319-74030-0_43}, pages = {542 -- 555}, year = {2018}, abstract = {Operational decisions in business processes can be modeled by using the Decision Model and Notation (DMN). The complementary use of DMN for decision modeling and of the Business Process Model and Notation (BPMN) for process design realizes the separation of concerns principle. For supporting separation of concerns during the design phase, it is crucial to understand which aspects of decision-making enclosed in a process model should be captured by a dedicated decision model. Whereas existing work focuses on the extraction of decision models from process control flow, the connection of process-related data and decision models is still unexplored. In this paper, we investigate how process-related data used for making decisions can be represented in process models and we distinguish a set of BPMN patterns capturing such information. Then, we provide a formal mapping of the identified BPMN patterns to corresponding DMN models and apply our approach to a real-world healthcare process.}, language = {en} } @misc{NeubauerWankoSchaubetal.2018, author = {Neubauer, Kai and Wanko, Philipp and Schaub, Torsten H. and Haubelt, Christian}, title = {Exact multi-objective design space exploration using ASPmT}, series = {Proceedings of the 2018 Design, Automation \& Test in Europe Conference \& Exhibition (DATE)}, journal = {Proceedings of the 2018 Design, Automation \& Test in Europe Conference \& Exhibition (DATE)}, publisher = {IEEE}, address = {New York}, isbn = {978-3-9819-2630-9}, issn = {1530-1591}, doi = {10.23919/DATE.2018.8342014}, pages = {257 -- 260}, year = {2018}, abstract = {An efficient Design Space Exploration (DSE) is imperative for the design of modern, highly complex embedded systems in order to steer the development towards optimal design points. The early evaluation of design decisions at system-level abstraction layer helps to find promising regions for subsequent development steps in lower abstraction levels by diminishing the complexity of the search problem. In recent works, symbolic techniques, especially Answer Set Programming (ASP) modulo Theories (ASPmT), have been shown to find feasible solutions of highly complex system-level synthesis problems with non-linear constraints very efficiently. In this paper, we present a novel approach to a holistic system-level DSE based on ASPmT. To this end, we include additional background theories that concurrently guarantee compliance with hard constraints and perform the simultaneous optimization of several design objectives. We implement and compare our approach with a state-of-the-art preference handling framework for ASP. Experimental results indicate that our proposed method produces better solutions with respect to both diversity and convergence to the true Pareto front.}, language = {en} } @misc{PufahlWongWeske2018, author = {Pufahl, Luise and Wong, Tsun Yin and Weske, Mathias}, title = {Design of an extensible BPMN process simulator}, series = {Business Process Management Workshops (BPM 2017)}, volume = {308}, journal = {Business Process Management Workshops (BPM 2017)}, publisher = {Springer}, address = {Berlin}, isbn = {978-3-319-74030-0}, issn = {1865-1348}, doi = {10.1007/978-3-319-74030-0_62}, pages = {782 -- 795}, year = {2018}, abstract = {Business process simulation is an important means for quantitative analysis of a business process and to compare different process alternatives. With the Business Process Model and Notation (BPMN) being the state-of-the-art language for the graphical representation of business processes, many existing process simulators support already the simulation of BPMN diagrams. However, they do not provide well-defined interfaces to integrate new concepts in the simulation environment. In this work, we present the design and architecture of a proof-of-concept implementation of an open and extensible BPMN process simulator. It also supports the simulation of multiple BPMN processes at a time and relies on the building blocks of the well-founded discrete event simulation. The extensibility is assured by a plug-in concept. Its feasibility is demonstrated by extensions supporting new BPMN concepts, such as the simulation of business rule activities referencing decision models and batch activities.}, language = {en} } @article{LambersBornKosioletal.2018, author = {Lambers, Leen and Born, Kristopher and Kosiol, Jens and Str{\"u}ber, Daniel and Taentzer, Gabriele}, title = {Granularity of conflicts and dependencies in graph transformation systems}, series = {Journal of Logical and Algebraic Methods in Programming}, volume = {103}, journal = {Journal of Logical and Algebraic Methods in Programming}, publisher = {Elsevier}, address = {New York}, issn = {2352-2208}, doi = {10.1016/j.jlamp.2018.11.004}, pages = {105 -- 129}, year = {2018}, abstract = {Conflict and dependency analysis (CDA) is a static analysis for the detection of conflicting and dependent rule applications in a graph transformation system. The state-of-the-art CDA technique, critical pair analysis, provides all potential conflicts and dependencies in minimal context as critical pairs, for each pair of rules. Yet, critical pairs can be hard to understand; users are mainly interested in core information about conflicts and dependencies occurring in various combinations. In this paper, we present an approach to conflicts and dependencies in graph transformation systems based on two dimensions of granularity. The first dimension refers to the overlap considered between the rules of a given rule pair; the second one refers to the represented amount of context information about transformations in which the conflicts occur. We introduce a variety of new conflict notions, in particular, conflict atoms, conflict reasons, and minimal conflict reasons, relate them to the existing conflict notions of critical pairs and initial conflicts, and position all of these notions within our granularity approach. Finally, we introduce dual concepts for dependency analysis. As we discuss in a running example, our approach paves the way for an improved CDA technique. (C) 2018 Elsevier Inc. All rights reserved.}, language = {en} } @article{GebserKaminskiKaufmannetal.2018, author = {Gebser, Martin and Kaminski, Roland and Kaufmann, Benjamin and Schaub, Torsten H.}, title = {Multi-shot ASP solving with clingo}, series = {Theory and practice of logic programming}, volume = {19}, journal = {Theory and practice of logic programming}, number = {1}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {1471-0684}, doi = {10.1017/S1471068418000054}, pages = {27 -- 82}, year = {2018}, abstract = {We introduce a new flexible paradigm of grounding and solving in Answer Set Programming (ASP), which we refer to as multi-shot ASP solving, and present its implementation in the ASP system clingo. Multi-shot ASP solving features grounding and solving processes that deal with continuously changing logic programs. In doing so, they remain operative and accommodate changes in a seamless way. For instance, such processes allow for advanced forms of search, as in optimization or theory solving, or interaction with an environment, as in robotics or query answering. Common to them is that the problem specification evolves during the reasoning process, either because data or constraints are added, deleted, or replaced. This evolutionary aspect adds another dimension to ASP since it brings about state changing operations. We address this issue by providing an operational semantics that characterizes grounding and solving processes in multi-shot ASP solving. This characterization provides a semantic account of grounder and solver states along with the operations manipulating them. The operative nature of multi-shot solving avoids redundancies in relaunching grounder and solver programs and benefits from the solver's learning capacities. clingo accomplishes this by complementing ASP's declarative input language with control capacities. On the declarative side, a new directive allows for structuring logic programs into named and parameterizable subprograms. The grounding and integration of these subprograms into the solving process is completely modular and fully controllable from the procedural side. To this end, clingo offers a new application programming interface that is conveniently accessible via scripting languages. By strictly separating logic and control, clingo also abolishes the need for dedicated systems for incremental and reactive reasoning, like iclingo and oclingo, respectively, and its flexibility goes well beyond the advanced yet still rigid solving processes of the latter.}, language = {en} } @misc{PlauthPolze2018, author = {Plauth, Max and Polze, Andreas}, title = {Towards improving data transfer efficiency for accelerators using hardware compression}, series = {Sixth International Symposium on Computing and Networking Workshops (CANDARW)}, journal = {Sixth International Symposium on Computing and Networking Workshops (CANDARW)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-9184-7}, doi = {10.1109/CANDARW.2018.00031}, pages = {125 -- 131}, year = {2018}, abstract = {The overhead of moving data is the major limiting factor in todays hardware, especially in heterogeneous systems where data needs to be transferred frequently between host and accelerator memory. With the increasing availability of hardware-based compression facilities in modern computer architectures, this paper investigates the potential of hardware-accelerated I/O Link Compression as a promising approach to reduce data volumes and transfer time, thus improving the overall efficiency of accelerators in heterogeneous systems. Our considerations are focused on On-the-Fly compression in both Single-Node and Scale-Out deployments. Based on a theoretical analysis, this paper demonstrates the feasibility of hardware-accelerated On-the-Fly I/O Link Compression for many workloads in a Scale-Out scenario, and for some even in a Single-Node scenario. These findings are confirmed in a preliminary evaluation using software-and hardware-based implementations of the 842 compression algorithm.}, language = {en} } @misc{MatthiesTeusnerHesse2018, author = {Matthies, Christoph and Teusner, Ralf and Hesse, G{\"u}nter}, title = {Beyond Surveys}, series = {2018 IEEE Frontiers in Education (FIE) Conference}, journal = {2018 IEEE Frontiers in Education (FIE) Conference}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-1174-6}, issn = {0190-5848}, pages = {9}, year = {2018}, language = {en} } @misc{TeusnerMatthiesStaubitz2018, author = {Teusner, Ralf and Matthies, Christoph and Staubitz, Thomas}, title = {What Stays in Mind?}, series = {IEEE Frontiers in Education Conference (FIE)}, journal = {IEEE Frontiers in Education Conference (FIE)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-1174-6}, issn = {0190-5848}, doi = {10.1109/FIE.2018.8658890}, pages = {9}, year = {2018}, language = {en} } @misc{RepkeKrestelEddingetal.2018, author = {Repke, Tim and Krestel, Ralf and Edding, Jakob and Hartmann, Moritz and Hering, Jonas and Kipping, Dennis and Schmidt, Hendrik and Scordialo, Nico and Zenner, Alexander}, title = {Beacon in the Dark}, series = {Proceedings of the 27th ACM International Conference on Information and Knowledge Management}, journal = {Proceedings of the 27th ACM International Conference on Information and Knowledge Management}, publisher = {Association for Computing Machinery}, address = {New York}, isbn = {978-1-4503-6014-2}, doi = {10.1145/3269206.3269231}, pages = {1871 -- 1874}, year = {2018}, abstract = {The large amount of heterogeneous data in these email corpora renders experts' investigations by hand infeasible. Auditors or journalists, e.g., who are looking for irregular or inappropriate content or suspicious patterns, are in desperate need for computer-aided exploration tools to support their investigations. We present our Beacon system for the exploration of such corpora at different levels of detail. A distributed processing pipeline combines text mining methods and social network analysis to augment the already semi-structured nature of emails. The user interface ties into the resulting cleaned and enriched dataset. For the interface design we identify three objectives expert users have: gain an initial overview of the data to identify leads to investigate, understand the context of the information at hand, and have meaningful filters to iteratively focus onto a subset of emails. To this end we make use of interactive visualisations based on rearranged and aggregated extracted information to reveal salient patterns.}, language = {en} } @misc{LosterNaumannEhmuelleretal.2018, author = {Loster, Michael and Naumann, Felix and Ehmueller, Jan and Feldmann, Benjamin}, title = {CurEx}, series = {Proceedings of the 27th ACM International Conference on Information and Knowledge Management}, journal = {Proceedings of the 27th ACM International Conference on Information and Knowledge Management}, publisher = {Association for Computing Machinery}, address = {New York}, isbn = {978-1-4503-6014-2}, doi = {10.1145/3269206.3269229}, pages = {1883 -- 1886}, year = {2018}, abstract = {The integration of diverse structured and unstructured information sources into a unified, domain-specific knowledge base is an important task in many areas. A well-maintained knowledge base enables data analysis in complex scenarios, such as risk analysis in the financial sector or investigating large data leaks, such as the Paradise or Panama papers. Both the creation of such knowledge bases, as well as their continuous maintenance and curation involves many complex tasks and considerable manual effort. With CurEx, we present a modular system that allows structured and unstructured data sources to be integrated into a domain-specific knowledge base. In particular, we (i) enable the incremental improvement of each individual integration component; (ii) enable the selective generation of multiple knowledge graphs from the information contained in the knowledge base; and (iii) provide two distinct user interfaces tailored to the needs of data engineers and end-users respectively. The former has curation capabilities and controls the integration process, whereas the latter focuses on the exploration of the generated knowledge graph.}, language = {en} } @misc{Matthies2018, author = {Matthies, Christoph}, title = {Scrum2kanban}, series = {Proceedings of the 2nd International Workshop on Software Engineering Education for Millennials}, journal = {Proceedings of the 2nd International Workshop on Software Engineering Education for Millennials}, publisher = {IEEE}, address = {New York}, isbn = {978-1-45035-750-0}, doi = {10.1145/3194779.3194784}, pages = {48 -- 55}, year = {2018}, abstract = {Using university capstone courses to teach agile software development methodologies has become commonplace, as agile methods have gained support in professional software development. This usually means students are introduced to and work with the currently most popular agile methodology: Scrum. However, as the agile methods employed in the industry change and are adapted to different contexts, university courses must follow suit. A prime example of this is the Kanban method, which has recently gathered attention in the industry. In this paper, we describe a capstone course design, which adds the hands-on learning of the lean principles advocated by Kanban into a capstone project run with Scrum. This both ensures that students are aware of recent process frameworks and ideas as well as gain a more thorough overview of how agile methods can be employed in practice. We describe the details of the course and analyze the participating students' perceptions as well as our observations. We analyze the development artifacts, created by students during the course in respect to the two different development methodologies. We further present a summary of the lessons learned as well as recommendations for future similar courses. The survey conducted at the end of the course revealed an overwhelmingly positive attitude of students towards the integration of Kanban into the course.}, language = {en} } @misc{ArandaSchoelzelMendezetal.2018, author = {Aranda, Juan and Sch{\"o}lzel, Mario and Mendez, Diego and Carrillo, Henry}, title = {An energy consumption model for multiModal wireless sensor networks based on wake-up radio receivers}, series = {2018 IEEE Colombian Conference on Communications and Computing (COLCOM)}, journal = {2018 IEEE Colombian Conference on Communications and Computing (COLCOM)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-6820-7}, doi = {10.1109/ColComCon.2018.8466728}, pages = {6}, year = {2018}, abstract = {Energy consumption is a major concern in Wireless Sensor Networks. A significant waste of energy occurs due to the idle listening and overhearing problems, which are typically avoided by turning off the radio, while no transmission is ongoing. The classical approach for allowing the reception of messages in such situations is to use a low-duty-cycle protocol, and to turn on the radio periodically, which reduces the idle listening problem, but requires timers and usually unnecessary wakeups. A better solution is to turn on the radio only on demand by using a Wake-up Radio Receiver (WuRx). In this paper, an energy model is presented to estimate the energy saving in various multi-hop network topologies under several use cases, when a WuRx is used instead of a classical low-duty-cycling protocol. The presented model also allows for estimating the benefit of various WuRx properties like using addressing or not.}, language = {en} } @article{MarufuKayemWolthusen2018, author = {Marufu, Anesu M. C. and Kayem, Anne Voluntas dei Massah and Wolthusen, Stephen D.}, title = {The design and classification of cheating attacks on power marketing schemes in resource constrained smart micro-grids}, series = {Smart Micro-Grid Systems Security and Privacy}, volume = {71}, journal = {Smart Micro-Grid Systems Security and Privacy}, publisher = {Springer}, address = {Dordrecht}, isbn = {978-3-319-91427-5}, doi = {10.1007/978-3-319-91427-5_6}, pages = {103 -- 144}, year = {2018}, abstract = {In this chapter, we provide a framework to specify how cheating attacks can be conducted successfully on power marketing schemes in resource constrained smart micro-grids. This is an important problem because such cheating attacks can destabilise and in the worst case result in a breakdown of the micro-grid. We consider three aspects, in relation to modelling cheating attacks on power auctioning schemes. First, we aim to specify exactly how in spite of the resource constrained character of the micro-grid, cheating can be conducted successfully. Second, we consider how mitigations can be modelled to prevent cheating, and third, we discuss methods of maintaining grid stability and reliability even in the presence of cheating attacks. We use an Automated-Cheating-Attack (ACA) conception to build a taxonomy of cheating attacks based on the idea of adversarial acquisition of surplus energy. Adversarial acquisitions of surplus energy allow malicious users to pay less for access to more power than the quota allowed for the price paid. The impact on honest users, is the lack of an adequate supply of energy to meet power demand requests. We conclude with a discussion of the performance overhead of provoking, detecting, and mitigating such attacks efficiently.}, language = {en} } @misc{HaarmannBatoulisNikajetal.2018, author = {Haarmann, Stephan and Batoulis, Kimon and Nikaj, Adriatik and Weske, Mathias}, title = {DMN Decision Execution on the Ethereum Blockchain}, series = {Advanced Information Systems Engineering, CAISE 2018}, volume = {10816}, journal = {Advanced Information Systems Engineering, CAISE 2018}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-91563-0}, issn = {0302-9743}, doi = {10.1007/978-3-319-91563-0_20}, pages = {327 -- 341}, year = {2018}, abstract = {Recently blockchain technology has been introduced to execute interacting business processes in a secure and transparent way. While the foundations for process enactment on blockchain have been researched, the execution of decisions on blockchain has not been addressed yet. In this paper we argue that decisions are an essential aspect of interacting business processes, and, therefore, also need to be executed on blockchain. The immutable representation of decision logic can be used by the interacting processes, so that decision taking will be more secure, more transparent, and better auditable. The approach is based on a mapping of the DMN language S-FEEL to Solidity code to be run on the Ethereum blockchain. The work is evaluated by a proof-of-concept prototype and an empirical cost evaluation.}, language = {en} } @misc{GrossTiwariHammer2018, author = {Gross, Sascha and Tiwari, Abhishek and Hammer, Christian}, title = {PlAnalyzer}, series = {Computer Security(ESORICS 2018), PT II}, volume = {11099}, journal = {Computer Security(ESORICS 2018), PT II}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-98989-1}, issn = {0302-9743}, doi = {10.1007/978-3-319-98989-1_3}, pages = {41 -- 59}, year = {2018}, abstract = {In this work we propose PIAnalyzer, a novel approach to analyze PendingIntent related vulnerabilities. We empirically evaluate PIAnalyzer on a set of 1000 randomly selected applications from the Google Play Store and find 1358 insecure usages of Pendinglntents, including 70 severe vulnerabilities. We manually inspected ten reported vulnerabilities out of which nine correctly reported vulnerabilities, indicating a high precision. The evaluation shows that PIAnalyzer is efficient with an average execution time of 13 seconds per application.}, language = {en} } @misc{GalkeGerstenkornScherp2018, author = {Galke, Lukas and Gerstenkorn, Gunnar and Scherp, Ansgar}, title = {A case atudy of closed-domain response suggestion with limited training data}, series = {Database and Expert Systems Applications : DEXA 2018 Iinternational workshops}, volume = {903}, journal = {Database and Expert Systems Applications : DEXA 2018 Iinternational workshops}, publisher = {Springer}, address = {Berlin}, isbn = {978-3-319-99133-7}, issn = {1865-0929}, doi = {10.1007/978-3-319-99133-7_18}, pages = {218 -- 229}, year = {2018}, abstract = {We analyze the problem of response suggestion in a closed domain along a real-world scenario of a digital library. We present a text-processing pipeline to generate question-answer pairs from chat transcripts. On this limited amount of training data, we compare retrieval-based, conditioned-generation, and dedicated representation learning approaches for response suggestion. Our results show that retrieval-based methods that strive to find similar, known contexts are preferable over parametric approaches from the conditioned-generation family, when the training data is limited. We, however, identify a specific representation learning approach that is competitive to the retrieval-based approaches despite the training data limitation.}, language = {en} } @misc{BlaesiusEubeFeldtkelleretal.2018, author = {Blaesius, Thomas and Eube, Jan and Feldtkeller, Thomas and Friedrich, Tobias and Krejca, Martin Stefan and Lagodzinski, Gregor J. A. and Rothenberger, Ralf and Severin, Julius and Sommer, Fabian and Trautmann, Justin}, title = {Memory-restricted Routing With Tiled Map Data}, series = {2018 IEEE International Conference on Systems, Man, and Cybernetics (SMC)}, journal = {2018 IEEE International Conference on Systems, Man, and Cybernetics (SMC)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-6650-0}, issn = {1062-922X}, doi = {10.1109/SMC.2018.00567}, pages = {3347 -- 3354}, year = {2018}, abstract = {Modern routing algorithms reduce query time by depending heavily on preprocessed data. The recently developed Navigation Data Standard (NDS) enforces a separation between algorithms and map data, rendering preprocessing inapplicable. Furthermore, map data is partitioned into tiles with respect to their geographic coordinates. With the limited memory found in portable devices, the number of tiles loaded becomes the major factor for run time. We study routing under these restrictions and present new algorithms as well as empirical evaluations. Our results show that, on average, the most efficient algorithm presented uses more than 20 times fewer tile loads than a normal A*.}, language = {en} } @misc{ElsaidShawishMeinel2018, author = {Elsaid, Mohamed Esam and Shawish, Ahmed and Meinel, Christoph}, title = {Enhanced cost analysis of multiple virtual machines live migration in VMware environments}, series = {2018 IEEE 8th International Symposium on Cloud and Service Computing (SC2)}, journal = {2018 IEEE 8th International Symposium on Cloud and Service Computing (SC2)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-7281-0236-8}, doi = {10.1109/SC2.2018.00010}, pages = {16 -- 23}, year = {2018}, abstract = {Live migration is an important feature in modern software-defined datacenters and cloud computing environments. Dynamic resource management, load balance, power saving and fault tolerance are all dependent on the live migration feature. Despite the importance of live migration, the cost of live migration cannot be ignored and may result in service availability degradation. Live migration cost includes the migration time, downtime, CPU overhead, network and power consumption. There are many research articles that discuss the problem of live migration cost with different scopes like analyzing the cost and relate it to the parameters that control it, proposing new migration algorithms that minimize the cost and also predicting the migration cost. For the best of our knowledge, most of the papers that discuss the migration cost problem focus on open source hypervisors. For the research articles focus on VMware environments, none of the published articles proposed migration time, network overhead and power consumption modeling for single and multiple VMs live migration. In this paper, we propose empirical models for the live migration time, network overhead and power consumption for single and multiple VMs migration. The proposed models are obtained using a VMware based testbed.}, language = {en} } @phdthesis{Kruse2018, author = {Kruse, Sebastian}, title = {Scalable data profiling}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-412521}, school = {Universit{\"a}t Potsdam}, pages = {ii, 156}, year = {2018}, abstract = {Data profiling is the act of extracting structural metadata from datasets. Structural metadata, such as data dependencies and statistics, can support data management operations, such as data integration and data cleaning. Data management often is the most time-consuming activity in any data-related project. Its support is extremely valuable in our data-driven world, so that more time can be spent on the actual utilization of the data, e. g., building analytical models. In most scenarios, however, structural metadata is not given and must be extracted first. Therefore, efficient data profiling methods are highly desirable. Data profiling is a computationally expensive problem; in fact, most dependency discovery problems entail search spaces that grow exponentially in the number of attributes. To this end, this thesis introduces novel discovery algorithms for various types of data dependencies - namely inclusion dependencies, conditional inclusion dependencies, partial functional dependencies, and partial unique column combinations - that considerably improve over state-of-the-art algorithms in terms of efficiency and that scale to datasets that cannot be processed by existing algorithms. The key to those improvements are not only algorithmic innovations, such as novel pruning rules or traversal strategies, but also algorithm designs tailored for distributed execution. While distributed data profiling has been mostly neglected by previous works, it is a logical consequence on the face of recent hardware trends and the computational hardness of dependency discovery. To demonstrate the utility of data profiling for data management, this thesis furthermore presents Metacrate, a database for structural metadata. Its salient features are its flexible data model, the capability to integrate various kinds of structural metadata, and its rich metadata analytics library. We show how to perform a data anamnesis of unknown, complex datasets based on this technology. In particular, we describe in detail how to reconstruct the schemata and assess their quality as part of the data anamnesis. The data profiling algorithms and Metacrate have been carefully implemented, integrated with the Metanome data profiling tool, and are available as free software. In that way, we intend to allow for easy repeatability of our research results and also provide them for actual usage in real-world data-related projects.}, language = {en} } @misc{DischerRichterDoellner2018, author = {Discher, S{\"o}ren and Richter, Rico and D{\"o}llner, J{\"u}rgen Roland Friedrich}, title = {A scalable webGL-based approach for visualizing massive 3D point clouds using semantics-dependent rendering techniques}, series = {Web3D 2018: The 23rd International ACM Conference on 3D Web Technology}, journal = {Web3D 2018: The 23rd International ACM Conference on 3D Web Technology}, editor = {Spencer, SN}, publisher = {Association for Computing Machinery}, address = {New York}, isbn = {978-1-4503-5800-2}, doi = {10.1145/3208806.3208816}, pages = {1 -- 9}, year = {2018}, abstract = {3D point cloud technology facilitates the automated and highly detailed digital acquisition of real-world environments such as assets, sites, cities, and countries; the acquired 3D point clouds represent an essential category of geodata used in a variety of geoinformation applications and systems. In this paper, we present a web-based system for the interactive and collaborative exploration and inspection of arbitrary large 3D point clouds. Our approach is based on standard WebGL on the client side and is able to render 3D point clouds with billions of points. It uses spatial data structures and level-of-detail representations to manage the 3D point cloud data and to deploy out-of-core and web-based rendering concepts. By providing functionality for both, thin-client and thick-client applications, the system scales for client devices that are vastly different in computing capabilities. Different 3D point-based rendering techniques and post-processing effects are provided to enable task-specific and data-specific filtering and highlighting, e.g., based on per-point surface categories or temporal information. A set of interaction techniques allows users to collaboratively work with the data, e.g., by measuring distances and areas, by annotating, or by selecting and extracting data subsets. Additional value is provided by the system's ability to display additional, context-providing geodata alongside 3D point clouds and to integrate task-specific processing and analysis operations. We have evaluated the presented techniques and the prototype system with different data sets from aerial, mobile, and terrestrial acquisition campaigns with up to 120 billion points to show their practicality and feasibility.}, language = {en} } @misc{SahlmannSchefflerSchnor2018, author = {Sahlmann, Kristina and Scheffler, Thomas and Schnor, Bettina}, title = {Ontology-driven Device Descriptions for IoT Network Management}, series = {2018 Global Internet of Things Summit (GIoTS)}, journal = {2018 Global Internet of Things Summit (GIoTS)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-6451-3}, doi = {10.1109/GIOTS.2018.8534569}, pages = {295 -- 300}, year = {2018}, abstract = {One particular challenge in the Internet of Things is the management of many heterogeneous things. The things are typically constrained devices with limited memory, power, network and processing capacity. Configuring every device manually is a tedious task. We propose an interoperable way to configure an IoT network automatically using existing standards. The proposed NETCONF-MQTT bridge intermediates between the constrained devices (speaking MQTT) and the network management standard NETCONF. The NETCONF-MQTT bridge generates dynamically YANG data models from the semantic description of the device capabilities based on the oneM2M ontology. We evaluate the approach for two use cases, i.e. describing an actuator and a sensor scenario.}, language = {en} } @phdthesis{Buschmann2018, author = {Buschmann, Stefan}, title = {A software framework for GPU-based geo-temporal visualization techniques}, doi = {10.25932/publishup-44340}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-443406}, school = {Universit{\"a}t Potsdam}, pages = {viii, 99}, year = {2018}, abstract = {R{\"a}umlich-zeitliche Daten sind Daten, welche sowohl einen Raum- als auch einen Zeitbezug aufweisen. So k{\"o}nnen beispielsweise Zeitreihen von Geodaten, thematische Karten die sich {\"u}ber die Zeit ver{\"a}ndern, oder Bewegungsaufzeichnungen von sich bewegenden Objekten als r{\"a}umlich-zeitliche Daten aufgefasst werden. In der heutigen automatisierten Welt gibt es eine wachsende Anzahl von Datenquellen, die best{\"a}ndig r{\"a}umlich-zeitliche Daten generieren. Hierzu geh{\"o}ren beispielsweise Verkehrs{\"u}berwachungssysteme, die Bewegungsdaten von Menschen oder Fahrzeugen aufzeichnen, Fernerkundungssysteme, welche regelm{\"a}ßig unsere Umgebung scannen und digitale Abbilder wie z.B. Stadt- und Landschaftsmodelle erzeugen, sowie Sensornetzwerke in unterschiedlichsten Anwendungsgebieten, wie z.B. der Logistik, der Verhaltensforschung von Tieren, oder der Klimaforschung. Zur Analyse r{\"a}umlich-zeitlicher Daten werden neben der automatischen Analyse mittels statistischer Methoden und Data-Mining auch explorative Methoden angewendet, welche auf der interaktiven Visualisierung der Daten beruhen. Diese Methode der Analyse basiert darauf, dass Anwender in Form interaktiver Visualisierung die Daten explorieren k{\"o}nnen, wodurch die menschliche Wahrnehmung sowie das Wissen der User genutzt werden, um Muster zu erkennen und dadurch einen Einblick in die Daten zu erlangen. Diese Arbeit beschreibt ein Software-Framework f{\"u}r die Visualisierung r{\"a}umlich-zeitlicher Daten, welches GPU-basierte Techniken beinhaltet, um eine interaktive Visualisierung und Exploration großer r{\"a}umlich-zeitlicher Datens{\"a}tze zu erm{\"o}glichen. Die entwickelten Techniken umfassen Datenhaltung, Prozessierung und Rendering und erm{\"o}glichen es, große Datenmengen in Echtzeit zu prozessieren und zu visualisieren. Die Hauptbeitr{\"a}ge der Arbeit umfassen: - Konzept und Implementierung einer GPU-zentrierten Visualisierungspipeline. Die beschriebenen Techniken basieren auf dem Konzept einer GPU-zentrierten Visualisierungspipeline, in welcher alle Stufen -- Prozessierung,Mapping, Rendering -- auf der GPU ausgef{\"u}hrt werden. Bei diesem Konzept werden die r{\"a}umlich-zeitlichen Daten direkt im GPU-Speicher abgelegt. W{\"a}hrend des Rendering-Prozesses werden dann mittels Shader-Programmen die Daten prozessiert, gefiltert, ein Mapping auf visuelle Attribute vorgenommen, und schließlich die Geometrien f{\"u}r die Visualisierung erzeugt. Datenprozessierung, Filtering und Mapping k{\"o}nnen daher in Echtzeit ausgef{\"u}hrt werden. Dies erm{\"o}glicht es Usern, die Mapping-Parameter sowie den gesamten Visualisierungsprozess interaktiv zu steuern und zu kontrollieren. - Interaktive Visualisierung attributierter 3D-Trajektorien. Es wurde eine Visualisierungsmethode f{\"u}r die interaktive Exploration einer großen Anzahl von 3D Bewegungstrajektorien entwickelt. Die Trajektorien werden dabei innerhalb einer virtuellen geographischen Umgebung in Form von einfachen Geometrien, wie Linien, B{\"a}ndern, Kugeln oder R{\"o}hren dargestellt. Durch interaktives Mapping k{\"o}nnen Attributwerte der Trajektorien oder einzelner Messpunkte auf visuelle Eigenschaften abgebildet werden. Hierzu stehen Form, H{\"o}he, Gr{\"o}ße, Farbe, Textur, sowie Animation zur Verf{\"u}gung. Mithilfe dieses dynamischen Mappings wurden außerdem verschiedene Visualisierungsmethoden implementiert, wie z.B. eine Focus+Context-Visualisierung von Trajektorien mithilfe von interaktiven Dichtekarten, sowie einer Space-Time-Cube-Visualisierung zur Darstellung des zeitlichen Ablaufs einzelner Bewegungen. - Interaktive Visualisierung geographischer Netzwerke. Es wurde eine Visualisierungsmethode zur interaktiven Exploration geo-referenzierter Netzwerke entwickelt, welche die Visualisierung von Netzwerken mit einer großen Anzahl von Knoten und Kanten erm{\"o}glicht. Um die Analyse von Netzwerken verschiedener Gr{\"o}ßen und in unterschiedlichen Kontexten zu erm{\"o}glichen, stehen mehrere virtuelle geographische Umgebungen zur Verf{\"u}gung, wie bspw. ein virtueller 3D-Globus, als auch 2D-Karten mit unterschiedlichen geographischen Projektionen. Zur interaktiven Analyse dieser Netzwerke stehen interaktive Tools wie Filterung, Mapping und Selektion zur Verf{\"u}gung. Des weiteren wurden Visualisierungsmethoden f{\"u}r verschiedene Arten von Netzwerken, wie z.B. 3D-Netzwerke und zeitlich ver{\"a}nderliche Netzwerke, implementiert. Zur Demonstration des Konzeptes wurden interaktive Tools f{\"u}r zwei unterschiedliche Anwendungsf{\"a}lle entwickelt. Das erste beinhaltet die Visualisierung attributierter 3D-Trajektorien, welche die Bewegungen von Flugzeugen um einen Flughafen beschreiben. Es erm{\"o}glicht Nutzern, die Trajektorien von ankommenden und startenden Flugzeugen {\"u}ber den Zeitraum eines Monats interaktiv zu explorieren und zu analysieren. Durch Verwendung der interaktiven Visualisierungsmethoden f{\"u}r 3D-Trajektorien und interaktiven Dichtekarten k{\"o}nnen Einblicke in die Daten gewonnen werden, wie beispielsweise h{\"a}ufig genutzte Flugkorridore, typische sowie untypische Bewegungsmuster, oder ungew{\"o}hnliche Vorkommnisse wie Fehlanfl{\"u}ge. Der zweite Anwendungsfall beinhaltet die Visualisierung von Klimanetzwerken, welche geographischen Netzwerken in der Klimaforschung darstellen. Klimanetzwerke repr{\"a}sentieren die Dynamiken im Klimasystem durch eine Netzwerkstruktur, die die statistische Beziehungen zwischen Orten beschreiben. Das entwickelte Tool erm{\"o}glicht es Analysten, diese großen Netzwerke interaktiv zu explorieren und dadurch die Struktur des Netzwerks zu analysieren und mit den geographischen Daten in Beziehung zu setzen. Interaktive Filterung und Selektion erm{\"o}glichen es, Muster in den Daten zu identifizieren, und so bspw. Cluster in der Netzwerkstruktur oder Str{\"o}mungsmuster zu erkennen.}, language = {en} } @phdthesis{Vogel2018, author = {Vogel, Thomas}, title = {Model-driven engineering of self-adaptive software}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-409755}, school = {Universit{\"a}t Potsdam}, pages = {xvi, 357}, year = {2018}, abstract = {The development of self-adaptive software requires the engineering of an adaptation engine that controls the underlying adaptable software by a feedback loop. State-of-the-art approaches prescribe the feedback loop in terms of numbers, how the activities (e.g., monitor, analyze, plan, and execute (MAPE)) and the knowledge are structured to a feedback loop, and the type of knowledge. Moreover, the feedback loop is usually hidden in the implementation or framework and therefore not visible in the architectural design. Additionally, an adaptation engine often employs runtime models that either represent the adaptable software or capture strategic knowledge such as reconfiguration strategies. State-of-the-art approaches do not systematically address the interplay of such runtime models, which would otherwise allow developers to freely design the entire feedback loop. This thesis presents ExecUtable RuntimE MegAmodels (EUREMA), an integrated model-driven engineering (MDE) solution that rigorously uses models for engineering feedback loops. EUREMA provides a domain-specific modeling language to specify and an interpreter to execute feedback loops. The language allows developers to freely design a feedback loop concerning the activities and runtime models (knowledge) as well as the number of feedback loops. It further supports structuring the feedback loops in the adaptation engine that follows a layered architectural style. Thus, EUREMA makes the feedback loops explicit in the design and enables developers to reason about design decisions. To address the interplay of runtime models, we propose the concept of a runtime megamodel, which is a runtime model that contains other runtime models as well as activities (e.g., MAPE) working on the contained models. This concept is the underlying principle of EUREMA. The resulting EUREMA (mega)models are kept alive at runtime and they are directly executed by the EUREMA interpreter to run the feedback loops. Interpretation provides the flexibility to dynamically adapt a feedback loop. In this context, EUREMA supports engineering self-adaptive software in which feedback loops run independently or in a coordinated fashion within the same layer as well as on top of each other in different layers of the adaptation engine. Moreover, we consider preliminary means to evolve self-adaptive software by providing a maintenance interface to the adaptation engine. This thesis discusses in detail EUREMA by applying it to different scenarios such as single, multiple, and stacked feedback loops for self-repairing and self-optimizing the mRUBiS application. Moreover, it investigates the design and expressiveness of EUREMA, reports on experiments with a running system (mRUBiS) and with alternative solutions, and assesses EUREMA with respect to quality attributes such as performance and scalability. The conducted evaluation provides evidence that EUREMA as an integrated and open MDE approach for engineering self-adaptive software seamlessly integrates the development and runtime environments using the same formalism to specify and execute feedback loops, supports the dynamic adaptation of feedback loops in layered architectures, and achieves an efficient execution of feedback loops by leveraging incrementality.}, language = {en} } @phdthesis{Bazhenova2018, author = {Bazhenova, Ekaterina}, title = {Discovery of Decision Models Complementary to Process Models}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-410020}, school = {Universit{\"a}t Potsdam}, year = {2018}, abstract = {Business process management is an acknowledged asset for running an organization in a productive and sustainable way. One of the most important aspects of business process management, occurring on a daily basis at all levels, is decision making. In recent years, a number of decision management frameworks have appeared in addition to existing business process management systems. More recently, Decision Model and Notation (DMN) was developed by the OMG consortium with the aim of complementing the widely used Business Process Model and Notation (BPMN). One of the reasons for the emergence of DMN is the increasing interest in the evolving paradigm known as the separation of concerns. This paradigm states that modeling decisions complementary to processes reduces process complexity by externalizing decision logic from process models and importing it into a dedicated decision model. Such an approach increases the agility of model design and execution. This provides organizations with the flexibility to adapt to the ever increasing rapid and dynamic changes in the business ecosystem. The research gap, identified by us, is that the separation of concerns, recommended by DMN, prescribes the externalization of the decision logic of process models in one or more separate decision models, but it does not specify this can be achieved. The goal of this thesis is to overcome the presented gap by developing a framework for discovering decision models in a semi-automated way from information about existing process decision making. Thus, in this thesis we develop methodologies to extract decision models from: (1) control flow and data of process models that exist in enterprises; and (2) from event logs recorded by enterprise information systems, encapsulating day-to-day operations. Furthermore, we provide an extension of the methodologies to discover decision models from event logs enriched with fuzziness, a tool dealing with partial knowledge of the process execution information. All the proposed techniques are implemented and evaluated in case studies using real-life and synthetic process models and event logs. The evaluation of these case studies shows that the proposed methodologies provide valid and accurate output decision models that can serve as blueprints for executing decisions complementary to process models. Thus, these methodologies have applicability in the real world and they can be used, for example, for compliance checks, among other uses, which could improve the organization's decision making and hence it's overall performance.}, language = {en} } @phdthesis{Herzberg2018, author = {Herzberg, Nico}, title = {Integrating events into non-automated business process environments}, school = {Universit{\"a}t Potsdam}, pages = {243}, year = {2018}, language = {en} } @misc{KovacsIonLopesetal.2018, author = {Kovacs, Robert and Ion, Alexandra and Lopes, Pedro and Oesterreich, Tim and Filter, Johannes and Otto, Philip and Arndt, Tobias and Ring, Nico and Witte, Melvin and Synytsia, Anton and Baudisch, Patrick}, title = {TrussFormer}, series = {UIST '18: Proceedings of the 31st Annual ACM Symposium on User Interface Software and Technology}, journal = {UIST '18: Proceedings of the 31st Annual ACM Symposium on User Interface Software and Technology}, publisher = {Association for Computing Machinery}, address = {New York}, isbn = {978-1-4503-5948-1}, doi = {10.1145/3242587.3242607}, pages = {113 -- 125}, year = {2018}, abstract = {We present TrussFormer, an integrated end-to-end system that allows users to 3D print large-scale kinetic structures, i.e., structures that involve motion and deal with dynamic forces. TrussFormer builds on TrussFab, from which it inherits the ability to create static large-scale truss structures from 3D printed connectors and PET bottles. TrussFormer adds movement to these structures by placing linear actuators into them: either manually, wrapped in reusable components called assets, or by demonstrating the intended movement. TrussFormer verifies that the resulting structure is mechanically sound and will withstand the dynamic forces resulting from the motion. To fabricate the design, TrussFormer generates the underlying hinge system that can be printed on standard desktop 3D printers. We demonstrate TrussFormer with several example objects, including a 6-legged walking robot and a 4m-tall animatronics dinosaur with 5 degrees of freedom.}, language = {en} } @phdthesis{Ion2018, author = {Ion, Alexandra}, title = {Metamaterial devices}, doi = {10.25932/publishup-42986}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429861}, school = {Universit{\"a}t Potsdam}, pages = {x, 173}, year = {2018}, abstract = {Digital fabrication machines such as 3D printers excel at producing arbitrary shapes, such as for decorative objects. In recent years, researchers started to engineer not only the outer shape of objects, but also their internal microstructure. Such objects, typically based on 3D cell grids, are known as metamaterials. Metamaterials have been used to create materials that, e.g., change their volume, or have variable compliance. While metamaterials were initially understood as materials, we propose to think of them as devices. We argue that thinking of metamaterials as devices enables us to create internal structures that offer functionalities to implement an input-process-output model without electronics, but purely within the material's internal structure. In this thesis, we investigate three aspects of such metamaterial devices that implement parts of the input-process-output model: (1) materials that process analog inputs by implementing mechanisms based on their microstructure, (2) that process digital signals by embedding mechanical computation into the object's microstructure, and (3) interactive metamaterial objects that output to the user by changing their outside to interact with their environment. The input to our metamaterial devices is provided directly by the users interacting with the device by means of physically pushing the metamaterial, e.g., turning a handle, pushing a button, etc. The design of such intricate microstructures, which enable the functionality of metamaterial devices, is not obvious. The complexity of the design arises from the fact that not only a suitable cell geometry is necessary, but that additionally cells need to play together in a well-defined way. To support users in creating such microstructures, we research and implement interactive design tools. These tools allow experts to freely edit their materials, while supporting novice users by auto-generating cells assemblies from high-level input. Our tools implement easy-to-use interactions like brushing, interactively simulate the cell structures' deformation directly in the editor, and export the geometry as a 3D-printable file. Our goal is to foster more research and innovation on metamaterial devices by allowing the broader public to contribute.}, language = {en} } @phdthesis{Lopes2018, author = {Lopes, Pedro}, title = {Interactive Systems Based on Electrical Muscle Stimulation}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-421165}, school = {Universit{\"a}t Potsdam}, pages = {171}, year = {2018}, abstract = {How can interactive devices connect with users in the most immediate and intimate way? This question has driven interactive computing for decades. Throughout the last decades, we witnessed how mobile devices moved computing into users' pockets, and recently, wearables put computing in constant physical contact with the user's skin. In both cases moving the devices closer to users allowed devices to sense more of the user, and thus act more personal. The main question that drives our research is: what is the next logical step? Some researchers argue that the next generation of interactive devices will move past the user's skin and be directly implanted inside the user's body. This has already happened in that we have pacemakers, insulin pumps, etc. However, we argue that what we see is not devices moving towards the inside of the user's body, but rather towards the body's biological "interface" they need to address in order to perform their function. To implement our vision, we created a set of devices that intentionally borrow parts of the user's body for input and output, rather than adding more technology to the body. In this dissertation we present one specific flavor of such devices, i.e., devices that borrow the user's muscles. We engineered I/O devices that interact with the user by reading and controlling muscle activity. To achieve the latter, our devices are based on medical-grade signal generators and electrodes attached to the user's skin that send electrical impulses to the user's muscles; these impulses then cause the user's muscles to contract. While electrical muscle stimulation (EMS) devices have been used to regenerate lost motor functions in rehabilitation medicine since the 1960s, in this dissertation, we propose a new perspective: EMS as a means for creating interactive systems. We start by presenting seven prototypes of interactive devices that we have created to illustrate several benefits of EMS. These devices form two main categories: (1) Devices that allow users eyes-free access to information by means of their proprioceptive sense, such as the value of a variable in a computer system, a tool, or a plot; (2) Devices that increase immersion in virtual reality by simulating large forces, such as wind, physical impact, or walls and heavy objects. Then, we analyze the potential of EMS to build interactive systems that miniaturize well and discuss how they leverage our proprioceptive sense as an I/O modality. We proceed by laying out the benefits and disadvantages of both EMS and mechanical haptic devices, such as exoskeletons. We conclude by sketching an outline for future research on EMS by listing open technical, ethical and philosophical questions that we left unanswered.}, language = {en} }