Experimental Evaluation of Book Drawing Algorithms

A $k$-page book drawing of a graph $G=(V,E)$ consists of a linear ordering of its vertices along a spine and an assignment of each edge to one of the $k$ pages, which are half-planes bounded by the spine. In a book drawing, two edges cross if and only if they are assigned to the same page and their vertices alternate along the spine. Crossing minimization in a $k$-page book drawing is NP-hard, yet book drawings have multiple applications in visualization and beyond. Therefore several heuristic book drawing algorithms exist, but there is no broader comparative study on their relative performance. In this paper, we propose a comprehensive benchmark set of challenging graph classes for book drawing algorithms and provide an extensive experimental study of the performance of existing book drawing algorithms.Comment: Appears in the Proceedings of the 25th International Symposium on Graph Drawing and Network Visualization (GD 2017

Parallelisation of genetic algorithms for the 2-page crossing number problem

Genetic algorithms have been applied to solve the 2-page crossing number problem successfully, but since they work with one global population, the search time and space are limited. Parallelisation provides an attractive prospect to improve the efficiency and solution quality of genetic algorithms. This paper investigates the complexity of parallel genetic algorithms (PGAs) based on two evaluation measures: Computation-time to Communication-time and Population-size to Chromosomesize. Moreover, the paper unifies the framework of PGA models with the function PGA (subpopulation size; cluster size, migration period; topology), and explores the performance of PGAs for the 2-page crossing number problem

Integrated design optimization methods for optimal sensor placement and cooling system architecture design for electro-thermal systems

Dynamic thermal management plays a very important role in the design and development of electro-thermal systems as these become more active and complex in terms of their functionalities. In highly power dense electronic systems, the heat is concentrated over small spatial domains. Thermal energy dissipation in any electrified system increases the temperature and might cause component failure, degradation of heat sensitive materials, thermal burnouts and failure of active devices. So thermal management needs to be done both accurately (by thermal monitoring using sensors) and efficiently (by applying fluid-based cooling techniques). In this work, two important aspects of dynamic thermal management of a highly dense power electronic system have been investigated. The first aspect is the problem of optimal temperature sensor placement for accurate thermal monitoring aimed toward achieving thermally-aware electrified systems. Strategic placement of temperature sensors can improve the accuracy of real-time temperature distribution estimates. Enhanced temperature estimation supports increased power throughput and density because Power Electronic Systems (PESs) can be operated in a less conservative manner while still preventing thermal failure. This work presents new methods for temperature sensor placement for 2- and 3-dimensional PESs that 1) improve computational efficiency (by orders of magnitude in at least one case), 2) support use of more accurate evaluation metrics, and 3) are scalable to high-dimension sensor placement problems. These new methods are tested via sensor placement studies based on a 2-kW, 60Hz, single-phase, Flying Capacitor Multi-Level (FCML) prototype inverter. Information-based metrics are derived from a reduced-order Resistance-Capacitance (RC) lumped parameter thermal model. Other more general metrics and system models are possible through application of a new continuous relaxation strategy introduced here for placement representation. A new linear Programming (LP) formulation is presented that is compatible with a particular type of information-based metric. This LP strategy is demonstrated to support the efficient solution of finely-discretized large-scale placement problems. The optimal sensor locations obtained from these methods were tested via physical experiments. The new methods and results presented here may aid the development of thermally-aware PESs with significantly enhanced capabilities. The second aspect is to design optimal fluid-based thermal management architectures through enumerative methods that help operate the system efficiently within its operating temperature limits using the minimum feasible coolant flow level. Expert intuition based on physics knowledge and vast experience may not be adequate to identify optimal thermal management designs as systems increase in size and complexity. This work also presents a design framework supporting comprehensive exploration of a class of single-phase fluid-based cooling architectures. The candidate cooling system architectures are represented using labeled rooted tree graphs. Dynamic models are automatically generated from these trees using a graph-based thermal modeling framework. Optimal performance is determined by solving an appropriate fluid flow distribution problem, handling temperature constraints in the presence of exogenous heat loads. Rigorous case studies are performed in simulation, with components having variable sets of heat loads and temperature constraints. Results include optimization of thermal endurance for an enumerated set of 4,051 architectures. In addition, cooling system architectures capable of steady-state operation under a given loading are identified. Optimization of the cooling system design has been done subject to a representative mission, consisting of multiple time-varying loads. Work presented in this thesis clearly shows that the transient effects of heat loads are expected to have important impacts on design decisions when compared to steady-state operating conditions

Sustainable Mobility and Transport

This Special Issue is dedicated to sustainable mobility and transport, with a special focus on technological advancements. Global transport systems are significant sources of air, land, and water emissions. A key motivator for this Special Issue was the diversity and complexity of mitigating transport emissions and industry adaptions towards increasingly stricter regulation. Originally, the Special Issue called for papers devoted to all forms of mobility and transports. The papers published in this Special Issue cover a wide range of topics, aiming to increase understanding of the impacts and effects of mobility and transport in working towards sustainability, where most studies place technological innovations at the heart of the matter. The goal of the Special Issue is to present research that focuses, on the one hand, on the challenges and obstacles on a system-level decision making of clean mobility, and on the other, on indirect effects caused by these changes

Graph Data-Models and Semantic Web Technologies in Scholarly Digital Editing

This volume is based on the selected papers presented at the Workshop on Scholarly Digital Editions, Graph Data-Models and Semantic Web Technologies, held at the Uni- versity of Lausanne in June 2019. The Workshop was organized by Elena Spadini (University of Lausanne) and Francesca Tomasi (University of Bologna), and spon- sored by the Swiss National Science Foundation through a Scientific Exchange grant, and by the Centre de recherche sur les lettres romandes of the University of Lausanne. The Workshop comprised two full days of vibrant discussions among the invited speakers, the authors of the selected papers, and other participants.1 The acceptance rate following the open call for papers was around 60%. All authors – both selected and invited speakers – were asked to provide a short paper two months before the Workshop. The authors were then paired up, and each pair exchanged papers. Paired authors prepared questions for one another, which were to be addressed during the talks at the Workshop; in this way, conversations started well before the Workshop itself. After the Workshop, the papers underwent a second round of peer-review before inclusion in this volume. This time, the relevance of the papers was not under discus- sion, but reviewers were asked to appraise specific aspects of each contribution, such as its originality or level of innovation, its methodological accuracy and knowledge of the literature, as well as more formal parameters such as completeness, clarity, and coherence. The bibliography of all of the papers is collected in the public Zotero group library GraphSDE20192, which has been used to generate the reference list for each contribution in this volume. The invited speakers came from a wide range of backgrounds (academic, commer- cial, and research institutions) and represented the different actors involved in the remediation of our cultural heritage in the form of graphs and/or in a semantic web en- vironment. Georg Vogeler (University of Graz) and Ronald Haentjens Dekker (Royal Dutch Academy of Sciences, Humanities Cluster) brought the Digital Humanities research perspective; the work of Hans Cools and Roberta Laura Padlina (University of Basel, National Infrastructure for Editions), as well as of Tobias Schweizer and Sepi- deh Alassi (University of Basel, Digital Humanities Lab), focused on infrastructural challenges and the development of conceptual and software frameworks to support re- searchers’ needs; Michele Pasin’s contribution (Digital Science, Springer Nature) was informed by his experiences in both academic research, and in commercial technology companies that provide services for the scientific community. The Workshop featured not only the papers of the selected authors and of the invited speakers, but also moments of discussion between interested participants. In addition to the common Q&A time, during the second day one entire session was allocated to working groups delving into topics that had emerged during the Workshop. Four working groups were created, with four to seven participants each, and each group presented a short report at the end of the session. Four themes were discussed: enhancing TEI from documents to data; ontologies for the Humanities; tools and infrastructures; and textual criticism. All of these themes are represented in this volume. The Workshop would not have been of such high quality without the support of the members of its scientific committee: Gioele Barabucci, Fabio Ciotti, Claire Clivaz, Marion Rivoal, Greta Franzini, Simon Gabay, Daniel Maggetti, Frederike Neuber, Elena Pierazzo, Davide Picca, Michael Piotrowski, Matteo Romanello, Maïeul Rouquette, Elena Spadini, Francesca Tomasi, Aris Xanthos – and, of course, the support of all the colleagues and administrative staff in Lausanne, who helped the Workshop to become a reality. The final versions of these papers underwent a single-blind peer review process. We want to thank the reviewers: Helena Bermudez Sabel, Arianna Ciula, Marilena Daquino, Richard Hadden, Daniel Jeller, Tiziana Mancinelli, Davide Picca, Michael Piotrowski, Patrick Sahle, Raffaele Viglianti, Joris van Zundert, and others who preferred not to be named personally. Your input enhanced the quality of the volume significantly! It is sad news that Hans Cools passed away during the production of the volume. We are proud to document a recent state of his work and will miss him and his ability to implement the vision of a digital scholarly edition based on graph data-models and semantic web technologies. The production of the volume would not have been possible without the thorough copy-editing and proof reading by Lucy Emmerson and the support of the IDE team, in particular Bernhard Assmann, the TeX-master himself. This volume is sponsored by the University of Bologna and by the University of Lausanne. Bologna, Lausanne, Graz, July 2021 Francesca Tomasi, Elena Spadini, Georg Vogele

Semantic discovery and reuse of business process patterns

Patterns currently play an important role in modern information systems (IS) development and their use has mainly been restricted to the design and implementation phases of the development lifecycle. Given the increasing significance of business modelling in IS development, patterns have the potential of providing a viable solution for promoting reusability of recurrent generalized models in the very early stages of development. As a statement of research-in-progress this paper focuses on business process patterns and proposes an initial methodological framework for the discovery and reuse of business process patterns within the IS development lifecycle. The framework borrows ideas from the domain engineering literature and proposes the use of semantics to drive both the discovery of patterns as well as their reuse