排序方式: 共有21条查询结果,搜索用时 15 毫秒
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Realization of a Framework for Simulation-Based Large-Scale Shape Optimization Using Vertex Morphing
Ghantasala Aditya Najian Asl Reza Geiser Armin Brodie Andrew Papoutsis Efthymios Bletzinger Kai-Uwe 《Journal of Optimization Theory and Applications》2021,189(1):164-189
Journal of Optimization Theory and Applications - There is a significant tendency in the industry for automation of the engineering design process. This requires the capability of analyzing an... 相似文献
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Tzinis Efthymios Wang Zhepei Jiang Xilin Smaragdis Paris 《Journal of Signal Processing Systems》2022,94(2):245-259
Journal of Signal Processing Systems - Recent progress in audio source separation led by deep learning has enabled many neural network models to provide robust solutions to this fundamental... 相似文献
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Global approximation to arbitrary cost functions: A Bayesian approach with application to US banking
Panayotis G. Michaelides Efthymios G. Tsionas Angelos T. Vouldis Konstantinos N. Konstantakis 《European Journal of Operational Research》2015
This paper proposes and estimates a globally flexible functional form for the cost function, which we call Neural Cost Function (NCF). The proposed specification imposes a priori and satisfies globally all the properties that economic theory dictates. The functional form can be estimated easily using Markov Chain Monte Carlo (MCMC) techniques or standard iterative SURE. We use a large panel of U.S. banks to illustrate our approach. The results are consistent with previous knowledge about the sector and in accordance with mathematical production theory. 相似文献
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Efthymios I. Ioannidis Terry Z. H. Gani Heather J. Kulik 《Journal of computational chemistry》2016,37(22):2106-2117
We present an automated, open source toolkit for the first‐principles screening and discovery of new inorganic molecules and intermolecular complexes. Challenges remain in the automatic generation of candidate inorganic molecule structures due to the high variability in coordination and bonding, which we overcome through a divide‐and‐conquer tactic that flexibly combines force‐field preoptimization of organic fragments with alignment to first‐principles‐trained metal‐ligand distances. Exploration of chemical space is enabled through random generation of ligands and intermolecular complexes from large chemical databases. We validate the generated structures with the root mean squared (RMS) gradients evaluated from density functional theory (DFT), which are around 0.02 Ha/au across a large 150 molecule test set. Comparison of molSimplify results to full optimization with the universal force field reveals that RMS DFT gradients are improved by 40%. Seamless generation of input files, preparation and execution of electronic structure calculations, and post‐processing for each generated structure aids interpretation of underlying chemical and energetic trends. © 2016 Wiley Periodicals, Inc. 相似文献
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Efthymios G. Tsionas 《商业与工业应用随机模型》1999,15(3):147-168
Very often, one needs to perform (classical or Bayesian) inference, when essentially nothing is known about the distribution of the dependent variable given certain covariates. The paper proposes to approximate the unknown distribution by its non-parametric counterpart—a step function—and treat the points of the support and the corresponding density values, as parameters, whose posterior distributions should be determined based on the available data. The paper proposes distributions should be determined based on the available data. The paper proposes Markov chain Monte Carlo methods to perform posterior analysis, and applies the new method to an analysis of stock returns. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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An improved multi-staged algorithmic process for the solution of the examination timetabling problem
Christos?GogosEmail author Panayiotis?Alefragis Efthymios?Housos 《Annals of Operations Research》2012,194(1):203-221
The efficient creation of examination timetables is a recurring and important problem for universities worldwide. Good timetables
typically are characterized by balanced distances between consecutive exams for all students. In this contribution an approach
for the examination timetabling problem as defined in the second International Timetabling Competition () is presented. The solution approach is managed on the top level by GRASP (Greedy Randomized Adaptive Search Procedure) and
it involves several optimization algorithms, heuristics and metaheuristics. A construction phase is executed first producing
a relatively high quality feasible solution and an improvement phase follows that further ameliorates the produced timetable.
Each phase consists of stages that are consumed in a circular fashion. The procedure produces feasible solutions for each
dataset provided under the runtime limit imposed by the rules of the ITC07 competition. Results are presented and analyzed. 相似文献
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G Carpintero E Rouvalis K Lawniczuk M Fice CC Renaud XJ Leijtens EA Bente M Chitoui F Van Dijk AJ Seeds 《Optics letters》2012,37(17):3657-3659
We report the generation of a 95?GHz carrier frequency by optical heterodyning of two wavelengths from adjacent channels from an arrayed waveguide grating-based multiwavelength laser. The extended cavity structure of the device provides low phase noise and narrow optical linewidth, further enhanced by the intracavity filter effect of the arrayed waveguide grating. We demonstrate that the generated RF beat note, at 95?GHz, has a -3 dB linewidth of 250?kHz. To the best of our knowledge, this is the narrowest RF linewidth generated from a free-running dual-wavelength semiconductor laser. The device is realized as a photonic integrated circuit using active-passive integration technology, and fabricated on a multiproject wafer run, constituting a novel approach for a compact, low-cost dual-wavelength heterodyne source. 相似文献