Institution
University of Coimbra
Education•Coimbra, Portugal•
About: University of Coimbra is a education organization based out in Coimbra, Portugal. It is known for research contribution in the topics: Population & Mitochondrion. The organization has 14318 authors who have published 43067 publications receiving 994733 citations. The organization is also known as: UC & Universidade dos Estudos Gerais.
Papers published on a yearly basis
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TL;DR: The results show that real-time TDDFT, as implemented in octopus, can be the method of choice for studying the excited states of large molecular systems in modern parallel architectures.
Abstract: Octopus is a general-purpose density-functional theory (DFT) code, with a particular emphasis on the time-dependent version of DFT (TDDFT). In this paper we present the ongoing efforts to achieve the parallelization of octopus. We focus on the real-time variant of TDDFT, where the time-dependent Kohn-Sham equations are directly propagated in time. This approach has great potential for execution in massively parallel systems such as modern supercomputers with thousands of processors and graphics processing units (GPUs). For harvesting the potential of conventional supercomputers, the main strategy is a multi-level parallelization scheme that combines the inherent scalability of real-time TDDFT with a real-space grid domain-partitioning approach. A scalable Poisson solver is critical for the efficiency of this scheme. For GPUs, we show how using blocks of Kohn-Sham states provides the required level of data parallelism and that this strategy is also applicable for code optimization on standard processors. Our results show that real-time TDDFT, as implemented in octopus, can be the method of choice for studying the excited states of large molecular systems in modern parallel architectures.
261 citations
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TL;DR: Two basic traction electric drive systems of electric/hybrid vehicles are presented and evaluated, with a special focus on the efficiency analysis of the main drive components efficiency, including the global drive efficiency, presented in the form of efficiency maps.
Abstract: One of the most important research topics in drive train topologies applied to electric/hybrid vehicles is the efficiency analysis of the power train components, including the global drive efficiency. In this paper, two basic traction electric drive systems of electric/hybrid vehicles are presented and evaluated, with a special focus on the efficiency analysis. The first topology comprises a traditional pulsewidth-modulation (PWM) battery-powered inverter, whereas in the second topology, the battery is connected to a bidirectional dc-dc converter, which supplies the inverter. Furthermore, a variable-voltage control technique applied to this second topology is presented, which allows for the improvement of the drive overall performance. Some simulation results are presented, considering both topologies and a permanent-magnet synchronous motor (PMSM). An even more detailed analysis is performed through the experimental validation. Particular attention is given to the evaluation of the main drive components efficiency, including the global drive efficiency, presented in the form of efficiency maps. Other parameters such as motor voltage distortion and power factor are also considered. In addition, the comparison of the two topologies takes into account the drive operation under the motoring and regenerative-braking modes.
261 citations
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University of Wrocław1, University of Washington2, University of Social Sciences and Humanities3, Baqiyatallah University of Medical Sciences4, King Saud University5, University of Ghana6, University of Milan7, The Chinese University of Hong Kong8, Pontifical Catholic University of Peru9, Federal University of Rio de Janeiro10, Moscow State University11, Russian State University for the Humanities12, Federal University of Rio Grande do Norte13, Ankara University14, University of Coimbra15, Babeș-Bolyai University16, Universidad Iberoamericana Ciudad de México17, İzmir University of Economics18, Charles University in Prague19, Saint Mary's University20, Akdeniz University21, Cumhuriyet University22, University of Zagreb23, Lviv University24, Federal Neuro Psychiatric Hospital25, University of Belgrade26, Central University of Finance and Economics27, University of Nairobi28, Norwegian University of Science and Technology29, National University of Entre Ríos30, Philadelphia University31, University of Granada32, University of Pécs33, Razi University34, University of Science and Culture35, University of Vienna36, Pontifical Catholic University of Rio de Janeiro37, Makerere University Business School38, Adekunle Ajasin University39, Universiti Utara Malaysia40, University of Nigeria, Nsukka41, University of Tartu42, University of Warwick43, University of Magdalena44, University of Karachi45, University of Constantine the Philosopher46, Dresden University of Technology47, University of Amsterdam48, South-West University "Neofit Rilski"49, Matej Bel University50, Indonesia University of Education51, Rio de Janeiro State University52, Indian Institute of Management Bangalore53, Indian Institute of Technology Guwahati54, Kyung Hee University55
TL;DR: In this paper, an extensive analysis of interpersonal distances over a large data set (N = 8,943 participants from 42 countries) was presented, which attempted to relate the preferred social, personal, and intimate distances observed in each country to a set of individual characteristics of the participants, and some attributes of their cultures.
Abstract: Human spatial behavior has been the focus of hundreds of previous research studies. However, the conclusions and generalizability of previous studies on interpersonal distance preferences were limited by some important methodological and sampling issues. The objective of the present study was to compare preferred interpersonal distances across the world and to overcome the problems observed in previous studies. We present an extensive analysis of interpersonal distances over a large data set (N = 8,943 participants from 42 countries). We attempted to relate the preferred social, personal, and intimate distances observed in each country to a set of individual characteristics of the participants, and some attributes of their cultures. Our study indicates that individual characteristics (age and gender) influence interpersonal space preferences and that some variation in results can be explained by temperature in a given region. We also present objective values of preferred interpersonal distances in different regions, which might be used as a reference data point in future studies.
260 citations
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TL;DR: In this paper, the authors define dynamic capability as the potential to systematically solve problems, enabled by its propensity to sense opportunities and threats, to make timely decisions, and to implement strategic decisions and changes efficiently, thereby ensuring the right direction.
260 citations
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TL;DR: This paper introduces two descent methods for a special instance of bileVEL programs where the inner problem is strictly convex quadratic and it is proved that checking local optimality in bilevel programming is a NP-hard problem.
Abstract: The bilevel programming problem involves two optimization problems where the data of the first one is implicitly determined by the solution of the second. In this paper, we introduce two descent methods for a special instance of bilevel programs where the inner problem is strictly convex quadratic. The first algorithm is based on pivot steps and may not guarantee local optimality. A modified steepest descent algorithm is presented to overcome this drawback. New rules for computing exact stepsizes are introduced and a hybrid approach that combines both strategies is discussed. It is proved that checking local optimality in bilevel programming is a NP-hard problem.
260 citations
Authors
Showing all 14693 results
Name | H-index | Papers | Citations |
---|---|---|---|
P. Chang | 170 | 2154 | 151783 |
Yang Gao | 168 | 2047 | 146301 |
Bin Liu | 138 | 2181 | 87085 |
P. Sinervo | 138 | 1516 | 99215 |
Filipe Veloso | 128 | 887 | 75496 |
Panagiotis Kokkas | 128 | 1234 | 81051 |
Nuno Filipe Castro | 128 | 960 | 76945 |
Robert Gardner | 128 | 1015 | 77619 |
Francois Corriveau | 128 | 1022 | 75729 |
Peter Krieger | 128 | 1171 | 81368 |
João Carvalho | 126 | 1278 | 77017 |
Helmut Wolters | 126 | 851 | 75721 |
Nicola Venturi | 126 | 796 | 69518 |
Sai-Juan Chen | 121 | 1211 | 73991 |
Harinder Singh Bawa | 120 | 798 | 66120 |