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Adaptive energy-preserving algorithms for guiding center system

Plasma science and Technology 2023年第4期25卷 11-22页

作者：朱贝贝刘健张嘉炜祝爱卿唐贻发 Department of Applied Mathematics School of Mathematics and PhysicsUniversity of Science and Technology BeijingBeijing 100083Peopleʼs Republic of China School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230026Peopleʼs Republic of China Advanced algorithm Joint Lab Shandong Computer Science CenterQilu University of TechnologyJinan 250014Peopleʼs Republic of China The State Key Laboratory of Scientific and Engineering Computing The Institute of Computational Mathematics and Scientific/Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190Peopleʼs Republic of China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049Peopleʼs Republic of China

We develop two types of adaptive energy preserving algorithms based on the averaged vector field for the guiding center dynamics,which plays a key role in magnetized *** adaptive scheme is applied to the Gauss Legendre’s quadrature rules and time stepsize respectively to overcome the energy drift problem in traditional energy-preserving *** new adaptive algorithms are second order,and their algebraic order is carefully *** results show that the global energy errors are bounded to the machine precision over long time using these adaptive algorithms without massive extra computation cost.

关键词： guiding center system energy-preserving methods adaptive energy conservation

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Design of Lowpass Filter and Wavelet Analysis for Electroretinogram in Dogs 38

Design of Lowpass Filter and Wavelet Analysis for Electroret...

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38th IEEE Region 10 Conference, TENCON 2023

作者： Tuntrik, Tunyawat Tuntivanich, Nalinee Banjerdpongchai, David Chulalongkorn University Center of Excellence in Intelligent Control Automation of Process Systems Faculty of Engineering Dept. of Electrical Engineering 254 Phayathai Road Pathumwan Bangkok10330 Thailand Faculty of Veterinary Science Dept. of Veterinary Surgery 254 Phayathai Road Pathumwan Bangkok10330 Thailand

ISBN: (纸本)9798350302196

In frequency domain, wavelet coefficient is one of the characteristics of ERG signal which is hidden in frequency-domain. This paper aims to develop a tool for analyzing the constituent frequencies and time of interest in the dog's ERG signal using wavelet analysis. We design a lowpass filter to reduce noise during the measurement of ERG response. ERG dataset was obtained for the light intensity series and their constituent frequencies are analyzed by using the continuous wavelet transform (CWT). The results show that, in time-domain, as light intensity increases, both amplitudes of a-wave and b-wave are higher. We can visualize the noise interference in the ERG signals. Then a lowpass filter is designed to attenuate the noise effect. The filtered signals have lower a-, and b-waves' amplitude which affect the important characteristics in time domain. Therefore, we choose to filter signal from 26ms onward, the main components are recovered, and the filtered signal becomes smoother. In frequency-domain, the peak magnitude of wavelet coefficients is increased as light intensity increases. © 2023 IEEE.

关键词： Wavelet transforms

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Inelastic neutron scattering of hydrogen in palladium studied by semiclassical dynamics

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Physical Review B 2024年第5期109卷 054303-054303页

作者： Motoyuki Shiga Bo Thomsen Hajime Kimizuka Center for Computational Science and e-Systems Japan Atomic Energy Agency Chiba 277-0871 Japan Department of Materials Design Innovation Engineering Nagoya University Aichi 464-8603 Japan

Inelastic neutron scattering (INS) spectra of hydrogen in face-centered cubic palladium have been calculated considering nuclear quantum effects (NQEs) at finite temperatures. The calculations were performed using semiclassical Brownian chain molecular dynamics (MD) [Shiga, J. Comput. Chem. 43, 1864 (2022)] and artificial neural network potentials with an accuracy of generalized gradient approximation of density functional theory. The calculated spectra are in good agreement with experimental spectra with respect to the peak positions and intensities corresponding to the fundamental tone and the first overtone of the vibrational excitation of hydrogen atoms. These results differ significantly from those of classical MD, indicating that NQE plays an essential role in the correct estimation of the INS spectrum. Importantly, the NQE acts as a blueshift of the INS spectrum for hydrogen in the octahedral site due to strong anharmonic vibrations of hydrogen on the potential surface with even symmetry. The calculated peak shifts associated with Pd lattice distortion were also in agreement with experimental results.

关键词： Hydrogen storage materials Ab initio molecular dynamics Inelastic neutron scattering Path-integral methods Semiclassical methods

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A symmetry-based length model for characterizing the hypersonic boundary layer transition on a slender cone at moderate incidence

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Advances in Aerodynamics 2022年第1期4卷 546-568页

作者： Wei-Tao Bi Zhou Wei Ke-Xin Zheng Zhen-Su She State Key Laboratory for Turbulence and Complex Systems and Department of Mechanics and Engineering Science College of EngineeringPeking UniversityBeijing100871China Science and Technology on Scramjet Laboratory China Aerodynamics Research and Development CenterMianyang621000China State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang621000China Computational Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang621000China

The hypersonic boundary layer(HBL)transition on a slender cone at moderate incidence is studied via a symmetry-based length model:the SED-SL *** SED-SL specifies an analytic stress length function(which defines the eddy viscosity)describing a physically sound two-dimensional multi-regime structure of transitional boundary *** studies showed accurate predictions,especially on the drag coefficient,by the SED-SL for airfoil flows at different subsonic Mach numbers,Reynolds numbers and angles of ***,the SED-SL is extended to compute the hypersonic heat transfer on a 7∘half-angle straight cone at Mach numbers 6 and 7 and angles of attack from 0∘to 6∘.It is shown that a proper setting of the multi-regime structure with three parameters(i.e.a transition center,an after-transition near-wall eddy length,and a transition width quantifying transition overshoot)yields an accurate description of the surface heat fluxes measured in wind *** good agreements between simulations and measurements are obtained from windward to leeward side of the cone,implying the validity of the multi-regime description of the transition independent of instability *** is concluded that a unified description for the HBL transition of cone is found,and might offer a basis for developing a new transition model that is simultaneously of computational simplicity,sound physics and greater accuracy.

关键词： Hypersonic boundary layer transition Transition model Cone Heat flux

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Minimizing the Number of Leaders in Impulsive Multi-Agent systems Under Switching Topologies

Minimizing the Number of Leaders in Impulsive Multi-Agent Sy...

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2023 China Automation Congress, CAC 2023

作者： Chen, Kaile Xue, Mengqi Huang, Jiahao Tang, Yang School of Information Science and Engineering East China University of Science and Technology Shanghai China College of Electronic and Information Engineering Shanghai Research Institute for Intelligent Autonomous Systems Tongji University Shanghai China The Key Laboratory of Smart Manufacturing in Energy Chemical Process Ministry of Education East China University of Science and Technology Shanghai200237 China The Frontiers Science Center for Intelligent Autonomous Systems Ministry of Education Tongji University Shanghai201210 China

ISBN: (纸本)9798350303759

In this paper, the leader selection problem is studied for impulsive general linear multi-agent systems under switching topologies, which minimizes the number of leaders subject to the consensus tracking performance. First, a consensus criterion for the studied multi-agent systems is derived. Second, leader selection metrics are established via the submodular optimization technique according to the proposed criterion. Third, a leader selection scheme is presented, with a polynomial-time algorithm that returns candidate leader sets. Finally, the effectiveness of the developed leader selection scheme is verified by numerical examples. © 2023 IEEE.

关键词： Multi agent systems

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Ultrathin curved PdNiRu nanosheets as bifunctional catalysts for oxygen reduction and ethylene glycol oxidation

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Nano Research 2024年第5期17卷 3777-3784页

作者： Xianzeng Li Tingyu Lu Huan Pang Mingyi Zhang Dongdong Xu Lin Xu Min Han Jun Yang Jiangsu Key Laboratory of New Power Batteries Jiangsu Collaborative Innovation Center of Biomedical Functional MaterialsSchool of Chemistry and Materials ScienceNanjing Normal UniversityNanjing 210023China Fujian Cross Strait Institute of Flexible Electronics(Future Technology) Fujian Normal UniversityFuzhou 350117China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China State Key Laboratory of Coordination Chemistry Nanjing UniversityNanjing 210023China School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225009China Key Laboratory for Photonic and Electronic Bandgap Materials Ministry of EducationSchool of Physics and Electronic EngineeringHarbin Normal UniversityHarbin 150025China

Pd-based metallic nanosheets with advanced physicochemical properties have been widely prepared and employed in various electrocatalytic ***,few concerns were focused on their multiple performances in different ***,highly curved and ultrathin PdNiRu nanosheets(NSs)are developed by facile wet-chemistry strategy and exhibit excellent electrocatalytic performance toward both oxygen reduction reaction(ORR)and ethylene glycol oxidation reaction(EGOR).Owing to the synergistically structural(e.g.,ultrathin,curved,defects/steps-rich)and compositional(ternary alloy)advantages,PdNiRu NSs exhibited enhanced ORR and EGOR specific/mass activities and better stability/durability than control *** specific activity(5.52 mA·cm^(−2))and mass activity(1.13 A·mg_(Pd)^(−1))of the PdNiRu NSs in ORR are 4.8 and 3.4 times as the ones of commercial Pt/C,*** mass activity of PdNiRu NSs(3.86 A·mg_(Pd)^(−1))in EGOR is 2.6 times as commercial Pd/C(1.51 A·mg_(Pd)^(−1)).This study is helpful for the development of desired electrocatalysts with multi-functional application in practical fuel cells.

关键词： ultrathin nanosheets noble metal electrocatalysts bifunctional

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Projected gradient descent algorithm for ab initio crystal structure relaxation under a fixed unit cell volume

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Physical Review B 2024年第22期109卷 224108-224108页

作者： Yukuan Hu Junlei Yin Xingyu Gao Xin Liu Haifeng Song Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China School of Mathematical Sciences Innovation Center NPU Chongqing Chongqing 401135 China National Key Laboratory of Computational Physics

This paper is concerned with ab initio crystal structure relaxation under a fixed unit cell volume, which is a step in calculating the static equations of state and forms the basis of thermodynamic property calculations for materials. The task can be formulated as an energy minimization with a determinant constraint. Widely used line minimization-based methods (e.g., conjugate gradient method) lack both efficiency and convergence guarantees due to the nonconvex nature of the determinant constraint as well as the significant differences in the curvatures of the potential energy surface with respect to atomic and lattice components. To this end, we propose a projected gradient descent algorithm named PANBB. It is equipped with (i) search direction projections for lattice vectors, (ii) distinct curvature-aware initial trial step sizes for atomic and lattice updates, and (iii) a nonrestrictive line minimization criterion as the stopping rule for the inner loop. It can be proved that PANBB favors theoretical convergence to equilibrium states. Across a benchmark set containing 223 structures from various categories, PANBB achieves average speedup factors of approximately 1.41 and 1.45 over the conjugate gradient method and direct inversion in the iterative subspace implemented in off-the-shelf simulation software, respectively. Moreover, it normally converges on all the systems, manifesting its robustness. As an application, we calculate the static equations of state for the high-entropy alloy AlCoCrFeNi, which remains elusive owing to 160 atoms representing both chemical and magnetic disorder and the strong local lattice distortion. The results are consistent with the previous calculations and are further validated by experimental thermodynamic data.

关键词： Crystal structure Structural properties Density functional theory

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Dimensionality and dynamics for next-generation artificial neural networks

Patterns

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Patterns 2025年

作者： Wang, Ge Fan, Feng-Lei Department of Biomedical Engineering Department of Electrical Computer and Systems Engineering Department of Computer Science Center for Computational Innovations Biomedical Imaging Center Center for Biotechnology and Interdisciplinary Studies Rensselaer Polytechnic Institute TroyNY United States Department of Data Science City University of Hong Kong Kowloon Hong Kong

The recent awarding of the Nobel Prize in Physics to Geoffrey E. Hinton and John J. Hopfield highlights their profound impact on artificial neural networks. In this perspective, we explore how their foundational insights can drive the advancement of next-generation artificial intelligence (AI) models. We propose expanding beyond conventional architectures by introducing dimensionality through intra-layer links and dynamics via feedback loops. Network height and additional dimensions, alongside traditional width and depth, enhance learning capabilities, while entangled loops across scales induce emergent behaviors akin to phase transitions in physics. We discuss how these principles extend beyond transformers, fostering a new paradigm of intelligence inspired by physics-driven models and biological cognition mechanisms. © 2025 The Author(s)

关键词： Neural network models

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Optimizing Maritime Propeller Design with Continuous Evolutionary Algorithms 13

Optimizing Maritime Propeller Design with Continuous Evoluti...

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13th IEEE Congress on Evolutionary Computation, CEC 2024

作者： Vogel, Joe Jonas De Almeida, Paulo Barbato Fogaça Drews, Paulo Lilles Jorge Marques, Crístofer Hood Carvalho, Jônata Tyska Federal University of Santa Catarina Department of Informatics and Statistics Florianópolis Brazil Federal University of Rio Grande Center for Computational Science Rio Grande Brazil School of Engineering Federal University of Rio Grande Rio Grande Brazil Florida State University Fsu Center for Advanced Power Systems TallahasseeFL United States

ISBN: (纸本)9798350308365

The vessels are powered by propellers that convert engine power into movement. Optimizing propeller design involves numerous variables like diameter and blade count, making exact methods impractical. Meta-heuristics, such as evolutionary algorithms, offer a promising solution. This study introduces a novel marine propeller optimization approach. It decomposes the optimization process and proposes a new fitness function to overcome previous limitations. Based on two continuous optimization algorithms, the approach was compared to the state-of-the-art differential evolution algorithm. Results from ferry-boat propeller design experiments show the proposed approach achieves approximately 1% higher efficiency than the baseline study at 7.0 and 7.5-knot speeds. The proposed approach succeeds at 8.0 and 8.5 knots, where the baseline failed. Additionally, decomposition reduces execution time by executing in six threads. © 2024 IEEE.

关键词： Constrained optimization

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Core-shell gold-copper nanoparticles:Evolution of copper shells on gold cores at different gold/copper precursor ratios

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Chinese Journal of Structural Chemistry 2023年第11期42卷 32-39页

作者： Shaonan Tian Yu Zhang Qing Zeng Junyu Zhong Hui Liu Lin Xu Jun Yang State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing100190China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing100049China State Key Laboratory of Bio-fibers and Eco-textiles Qingdao UniversityQingdao266071China School of Chemistry and Materials Science Jiangsu Key Laboratory of New Power BatteriesJiangsu Collaborative Innovation Centre of Biomedical Functional MaterialsNanjing Normal UniversityNanjing210023China

Core-shell nanostructures usually exhibit tunable catalytic properties in comparison with their single core or shell counterpart due to electronic interaction and lattice strain between the core and shell ***,we report the intriguing evolution of copper(Cu)shells on the gold(Au)cores at different Au/Cu precursor ratios during the synthesis of core-shell Au-Cu nanoparticles at an organic medium via seed-mediated growth *** brief,at relatively low Cu ratios,quasi-spherical Au-Cu nanoparticles with conventional core-shell structures are the majority products,in which the Cu shell thickness increases with the increase of Cu precursor *** dif-ference is that at high Cu ratios,the Cu shells no longer increase their thickness,but evolve into a dendritic ***,the core-shell Au-Cu nanoparticles with dendritic Cu shells could be transformed into interesting Au-Cu cage-bell structures after a ripening process at elevated ***,through galvanic replacement reaction with Pt precursors,the thin Cu shells could be converted into CuPt alloy shells on the Au cores,which exhibit enhanced activity towards methanol oxidation reaction with satisfactory durability,in comparison with that of commercial Pt/C catalysts.

关键词： Core-shell nanostructure Seed-mediated growth Electronic interaction Lattice strain Methanol oxidation reaction

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