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arXiv 2021年

作者： Vanaret, Charlie Department of Applied Algorithmic Intelligence Methods Zuse-Institut Berlin Berlin14195 Germany

In this article, we propose an interval constraint programming method for globally solving catalog-based categorical optimization problems. It supports catalogs of arbitrary size and properties of arbitrary dimension, and does not require any modeling effort from the user. A novel catalog-based contractor (or filtering operator) guarantees consistency between the categorical properties and the existing catalog items. This results in an intuitive and generic approach that is exact, rigorous (robust to roundoff errors) and can be easily implemented in an off-the-shelf interval-based continuous solver that interleaves branching and constraint propagation. We demonstrate the validity of the approach on a numerical problem in which a categorical variable is described by a two-dimensional property space. A Julia prototype is available as open-source software under the MIT license at https://***/cvanaret/***. © 2021, CC BY.

关键词： Global optimization

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Effect of Inertia Force on the Interface Stability of a Tangential-Velocity Discontinuity in Porous Media

SSRN

引用

SSRN 2023年

作者： Le, Thi Thai Koch, Thorsten Zuse Institute Berlin Applied Algorithmic Intelligence Methods Department Takustr. 7 Berlin14195 Germany TU Berlin Chair of Software and Algorithms for Discrete Optimization Str. des 17. Juni 135 Berlin10623 Germany

The present study investigates the stability of a tangential-velocity discontinuity in porous media during the withdrawing and injecting processes of natural gases from and into underground gas storages. The focus is on analyzing the impact of inertia forces on the interface stability using the Forchheimer equations. Other publications have relied primarily on Darcy's law to describe flow stability in porous media. However, Darcy's law only adequately describes flows in which viscous forces dominate over inertia forces. As the flow rate increases, the significance of inertia forces becomes more pronounced, and Darcy's law becomes insufficient for describing such flows. Our findings indicate that even a slight consideration of the inertia effect leads to permanent destabilization of the discontinuity interface, regardless of the fluid viscosity or the Mach number. In contrast, when the inertia effect is neglected, the interface is stabilized across the entire Mach number range if the fluid viscosity is strong enough. © 2023, The Authors. All rights reserved.

关键词： Porous materials

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The variational bayesian inference for network autoregression models

arXiv

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arXiv 2021年

作者： Lai, Wei-Ting Chen, Ray-Bing Chen, Ying Koch, Thorsten Department of Statistics National Cheng Kung University Tainan Taiwan Institute of Data Science National Cheng Kung University Tainan Taiwan Department of Mathematics National University of Singapore Singapore Risk Management Institute National University of Singapore Singapore Institute of Data Science National University of Singapore Singapore Chair of Software and Algorithms for Discrete Optimization Technische Universität Berlin Berlin Germany Department of Applied Algorithmic Intelligence Methods Zuse Institute Berlin Berlin Germany

We develop a variational Bayesian (VB) approach for estimating large-scale dynamic network models in the network autoregression framework. The VB approach allows for the automatic identification of the dynamic structure of such a model and obtains a direct approximation of the posterior density. Compared to Markov Chain Monte Carlo (MCMC) based sampling approaches, the VB approach achieves enhanced computational efficiency without sacrificing estimation accuracy. In the simulation study conducted here, the proposed VB approach detects various types of proper active structures for dynamic network models. Compared to the alternative approach, the proposed method achieves similar or better accuracy, and its computational time is halved. In a real data analysis scenario of day-ahead natural gas flow prediction in the German gas transmission network with 51 nodes between October 2013 and September 2015, the VB approach delivers promising forecasting accuracy along with clearly detected structures in terms of dynamic dependence. Copyright © 2021, The Authors. All rights reserved.

关键词： Computational efficiency

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Which algorithm to select in sports timetabling?

arXiv

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arXiv 2023年

作者： Van Bulck, David Goossens, Dries Clarner, Jan-Patrick Dimitsas, Angelos Fonseca, George H.G. Lamas-Fernandez, Carlos Lester, Martin Mariusz Pedersen, Jaap Phillips, Antony E. Rosati, Roberto Maria Faculty of Economics and Business Administration Ghent University Tweekerkenstraat 2 Ghent9000 Belgium Core lab CVAMO FlandersMake@UGent Belgium Applied Algorithmic Intelligence Methods Department Zuse Institute Berlin Takustrase 7 Berlin14195 Germany Department of Informatics University of Ioannina University of Ioannina Greece Computing and Systems Department Federal University of Ouro Preto R. Diogo de Vasconcelos 122 Ouro Preto Brazil Southampton Business School University of Southampton United Kingdom Department of Computer Science University of Reading Reading United Kingdom 7bridges *** 23 Meard St London United Kingdom DPIA University of Udine via delle Scienze 206 Udine33100 Italy

Any sports competition needs a timetable, specifying when and where teams meet each other. The recent International Timetabling Competition (ITC2021) on sports timetabling showed that, although it is possible to develop general algorithms, the performance of each algorithm varies considerably over the problem instances. This paper provides a problem type analysis for sports timetabling, resulting in powerful insights into the strengths and weaknesses of eight state-of-the-art algorithms. Based on machine learning techniques, we propose an algorithm selection system that predicts which algorithm is likely to perform best based on the type of competition and constraints being used (i.e., the problem type) in a given sports timetabling problem instance. Furthermore, we visualize how the problem type relates to algorithm performance, providing insights and possibilities to further enhance several algorithms. Finally, we assess the empirical hardness of the instances. Our results are based on large computational experiments involving about 50 years of CPU time on more than 500 newly generated problem instances. © 2023, CC BY-NC-ND.

关键词： Scheduling algorithms

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Article's Scientific Prestige: Measuring the impact of individual articles in the Web of Science

arXiv

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arXiv 2022年

作者： Chen, Ying Koch, Thorsten Zakiyeva, Nazgul Liu, Kailiang Xu, Zhitong Chen, Chun-Houh Nakano, Junji Honda, Keisuke Department of Mathematics National University of Singapore 2 Science Drive 2 Singapore117543 Singapore Risk Management Institute National University of Singapore 21 Heng Mui Keng Terrace 04-03 Singapore119613 Singapore Technische Universität Berlin Software and Algorithms for Discrete Optimization Straße des 17. Juni 135 Berlin10623 Germany Zuse Institute Berlin Applied Algorithmic Intelligence Methods Department Takustraße 7 Berlin14195 Germany Research Institute Chongqing Internet Institute Building 5B No. 16 South Huashan Road Chongqing Liang Jiang New Area Chongqing China Department of Statistics and Data Science National University of Singapore 6 Science Drive 2 Singapore117546 Singapore The Institute of Statistical Science Academia Sinica 128 Academia Road Nankang Taipei11529 Taiwan Department of Global Management Chuo University 742-1 Higashinakano Hachioji Tokyo192-0393 Japan Institute of Statistical Mathematics 10-3 Midoricho Tachikawa Tokyo190-0014 Japan

We performed a citation analysis on the Web of Science publications consisting of more than 63 million articles and 1.45 billion citations on 254 subjects from 1981 to 2020. We proposed the Article's Scientific Prestige (ASP) metric and compared this metric to number of citations (#Cit) and journal grade in measuring the scientific impact of individual articles in the large-scale hierarchical and multi-disciplined citation network. In contrast to #Cit, ASP, that is computed based on the eigenvector centrality, considers both direct and indirect citations, and provides steady-state evaluation cross different disciplines. We found that ASP and #Cit are not aligned for most articles, with a growing mismatch amongst the less cited articles. While both metrics are reliable for evaluating the prestige of articles such as Nobel Prize winning articles, ASP tends to provide more persuasive rankings than #Cit when the articles are not highly cited. The journal grade, that is eventually determined by a few highly cited articles, is unable to properly reect the scientific impact of individual articles. The number of references and coauthors are less relevant to scientiffc impact, but subjects do make a difference. Copyright © 2022, The Authors. All rights reserved.

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