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NURBS-based DEM for non-spherical particles

Particuology 2020年第2期18卷 65-76页

作者： Shiwen Liu Feiguo Chen Wei Ge Philippe Ricoux State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesP.O.Box 353Beijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China Data Processing and Modeling TOTAL Scientific DivisionFrance

The discrete element method(DEM)is used to analyze complex practical granular systems;however,the representation of real shapes is an important consideration because behavior of non-spherical particles is unlike that of spherical particles both individually and *** this study,we use non-uniform rational basis-splines(NURBS)to describe the shapes of non-spherical particles and introduce a contact detection scheme based on quadratic convergence,to simulate the behaviors of elliptical *** simulation results are compared with those based on polygons,in terms of the shape description and contact treatment,to demonstrate the high accuracy and efficiency of NURBS-based DEM.

关键词： Non-spherical particle Discrete element method NURBS Facet-based DEM Granular system

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Thermodynamically Consistent Hybrid Computational Models for Fluid-Particle Interactions

SSRN

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SSRN 2023年

作者： Hong, Qi Wang, Qi School of Mathematics Nanjing University of Aeronautics and Astronautics Nanjing211106 China MIIT Nanjing211106 China Key Laboratory of Numerical Simulation for Large Scale Complex Systems Nanjing Normal University Ministry of Education Nanjing210023 China Department of Mathematics University of South Carolina ColumbiaSC29208 United States

We introduce a novel computational framework designed to explore the dynamic interactions between fluid and solid particles or structures immersed in a viscous fluid medium. This innovative framework harnesses the power of the phase-field-embedding method, in which each solid component, whether rigid or elastic, is characterized by a volume-preserving phase field. The unified velocity within the fluid-solid ensemble governs the movement of both solid particles and the surrounding fluid, specifically for passive particles. Active particles, however, are not only influenced by this unified velocity but are also driven by their self-propelling velocities. To capture exclusive volume interactions among particles and between particles and boundaries, we employ repulsive potential forces at a coarser scale. These forces effectively model repulsion and collision effects. Rigid particles maintain structural integrity by enforcing a zero velocity gradient tensor within their spatial domains, necessitating the introduction of a constraining stress tensor. In contrast, elastic particles are governed by a quasi-linear constitutive equation describing the elastic stress within their domains, allowing for accurate modeling of their deformations. The motion of solid particles is tracked by monitoring the dynamics of their centers of mass. This approach facilitates the development of a hybrid, thermodynamically consistent hydrodynamic model applicable to both rigid and elastic particles. Adhering to the generalized Onsager principle, this model spans the entire computational domain. To numerically solve this thermodynamically consistent model for elastic particles, we present a structure-preserving numerical algorithm. Notably, in the limit of an infinite elastic modulus, this algorithm converges to the one employed for modeling rigid particles. Finally, we substantiate the effectiveness, accuracy, and stability of our proposed scheme through a series of numerical experiments. Thes

关键词： Hydrodynamics

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Dynamical relaxation behavior of an extended XY chain with a gapless phase following a quantum quench

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Physical Review B 2024年第2期109卷 024303-024303页

作者： Kaiyuan Cao Yayun Hu Peiqing Tong Guangwen Yang Zhejiang Lab Hangzhou 311100 People's Republic of China Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing 210023 People's Republic of China and Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 People's Republic of China Zhejiang Lab Hangzhou 311100 People's Republic of China and Department of Computer Science and Technology Tsinghua University Haidian District Beijing 100084 People's Republic of China

We investigate the dynamical relaxation behavior of the two-point correlation in extended XY models with a gapless phase after quenches from various initial states. Specifically, we study the XY chain with gapless phase induced by the following additional interactions: Dzyaloshinskii-Moriya interaction and the XZY-YZX type of three-site interaction. When quenching from the gapped phase, we observe that the additional interactions have no effect on the relaxation behavior. The relaxation behavior is δCmn(t)∼t−3/2 and ∼t−1/2 for the quench to the commensurate phase and the incommensurate phase, respectively. However, when quenching from the gapless phase, we demonstrate that the scaling behavior of δCmn(t) is changed to ∼t−1 for the quench to the commensurate phase, and the decay of δCmn(t) follows ∼t−1 or ∼t−1/2 for the quench to the incommensurate phase depending on the parameters of prequench Hamiltonian. We also establish the dynamical phase diagrams based on the dynamical relaxation behavior of δCmn(t) in the extended XY models.

关键词： Dynamical phase transitions Dzyaloshinskii-Moriya interaction Quantum quench XY model

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Non-Rigid Metal–Oxygen Bonding Empowered Nitrate Reduction on Ruthenium Catalysts

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SSRN 2024年

作者： Wang, Suwen Zhuang, Zechao Xu, Jiawei Fu, Cheng Qiu, Zhen Feng, Huajun Xiang, Hai Chen, Zuliang Li, Hui Zhang, Lei Li, Yongfu Cai, Yanjiang Ma, Tianyi Yu, Bing State Key Laboratory of Subtropical Silviculture Zhejiang A&F University Hangzhou311300 China Zhejiang A&F University Hangzhou311300 China Department of Chemistry Tsinghua University Beijing100084 China Jiangsu Key Laboratory of Numerical Simulation of Large Scale Complex Systems School of Chemistry and Materials Science Nanjing Normal University Nanjing210023 China Fujian Key Laboratory of Pollution Control and Resource Reuse School of Environmental and Resource Sciences Fujian Normal University Fujian Province Fuzhou350007 China School of Science RMIT University MelbourneVIC3000 Australia Centre for Translational Atomaterials

Electrocatalytic nitrate reduction (NitRR) offers exciting potential for mass production of ammonia (NH3) from renewables. However, the rigidity of metal−ligand bonds in most electrocatalysts renders them unable to survive the structural transformations required for NitRR. Herein, we establish a type of non-rigid metal−oxygen bonds by employing graphene oxide (GO) sheets as a 'micron-scale' ligand for transition metals (TM). Because of being confined to the interfaces between GO and TM, the oxygenated groups in GO can associate with and dissociate from the TM in response to reaction dynamics. As a proof-of-concept demonstration, an electrocatalyst was developed by dispersing nanoscale ruthenium (Ru) on graphene oxide (GO) and utilizing two-dimensional MXene to compensate for the low electrical conductivity of GO. This electrocatalyst exhibits a maximum NH3 yield of over 5 mg cm−2 h−1, with almost 100% current-to-NH3 efficiency, far outperforming the performance of most reported Ru-based materials. What's even more remarkable is the achievement of a record-breaking performance: a 200-hour stable electrolysis with a NH3 yield of 40.2 mg cm−2 h−1, using a membrane electrode reactor. Our experimental and theoretical investigations further reveal the non-rigidity of the Ru–O bonds and how they self-regulate to adapt to diverse intermediates involved in NitRR. This work provides an approach to fabricate a high-performance electrocatalyst featuring reversible and non-rigid metal−oxygen bonds, opening new possibilities for practical nitrate electrolysis. © 2024, The Authors. All rights reserved.

关键词： Electrocatalysis

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Finite-Time Quasi-Projective Synchronization of Fractional-Order Reaction-Diffusion Delayed Neural Networks

SSRN

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SSRN 2024年

作者： Wang, Zhenjie Zhang, Weiwei Zhang, Hai Chen, Dingyuan Cao, Jinde Abdel-Aty, Mahmoud School of Mathematics and Physics Anqing Normal University Anqing246133 China Department of Mathematics Nanjing University of Aeronautics and Astronautics Nanjing210093 China Key Laboratory of Modeling Simulation and Control of Complex Ecosystem in Dabie Mountains of Anhui Higher Education Institutes Anqing Normal University Anqing246133 China School of Mathematics Southeast University Nanjing210096 China Deanship of Graduate Studies and Scientific Research Ahlia University Manama10878 Bahrain

The problem of the finite-time quasi-projective synchronization (FTQPS) of fractional-order reaction-diffusion neural networks (FORDNNs) is examined by this paper. First, on the basis of the characterization of the reaction diffusion term and the concept of inequality deflation, an integral-type Lyapunov function is constructed. Subsequently, a nonlinear feedback control strategy is constructed, and sufficient conditions for FTQPS of the developed model are derived. Further, the system's synchronization speed is measured by estimating the settling time. It should be noted that the above control strategy is also applicable to conventional integer order RDNNs with time delay. Finally, a nu merical example is used to illustrate the veracity and validity of the theoretical analysis presented. © 2024, The Authors. All rights reserved.

关键词： Lyapunov functions

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Frequency and Voltage Computation on Protection Settings in Renewable Resources 4

Frequency and Voltage Computation on Protection Settings in ...

引用

4th IEEE Workshop on Power Electronics and Power Quality Applications (PEPQA)

作者： Arias-Guzman, S. Ustariz-Farfan, A. J. Cano-Plata, E. A. McCann, Roy Key Laboratory of Complex Systems Modeling and Simulation Ministry of Education Hangzhou Dianzi University Hangzhou China Computing Center Shanghai University Shanghai China

ISBN: (纸本)9781728116266

The presence of inverter based renewable resources has introducing new challenges on transmission systems due sudden loss of several MW after voltage and frequency excursions. These sudden disconnections have been related with a fault ride through control in voltage and frequency excursions following PRC-024 standard. The NERC Inverter-Based Resource Performance Task Force has expressed the necessity for a full ride-through standard with clear requirements as to how the resource can behave in terms on control and protection aspects. In consequence, this article addresses the problem to define the control and protection that can be taken under frequency and voltage excursions to avoid disconnections. For this purpose, this article proposes a new magnitude and frequency computation with computations delays under 16 ms and the use of new detection techniques to add new control and protection functions to the inverter based renewable resources.

关键词： Momentary Cessation Protection systems Frequency computation Estate estimation Renewable resources

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Charmoniumlike tetraquarks in a chiral quark model

arXiv

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arXiv 2023年

作者： Yang, Gang Ping, Jialun Segovia, Jorge Department of Physics Zhejiang Normal University Jinhua321004 China Department of Physics Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China Departamento de Sistemas Físicos Químicos y Naturales Universidad Pablo de Olavide SevillaE-41013 Spain

The lowest-lying charmonium-like tetraquarks (Equation presented) (q = u, d) and (Equation presented), with spin-parity JP = 0+, 1+ and 2+, and isospin I = 0 and 1, are systematically investigated within the theoretical framework of complex-scaling range for a chiral quark model that has already been successfully applied in former studies of various tetra- and penta-quark systems. A four-body S-wave configuration which includes meson-meson, diquark-antidiquark and K-type arrangements of quarks, along with all possible color wave functions, is comprehensively considered. Several narrow resonances are obtained in each tetraquark channel when a fully coupled-channel computation is performed. We tentatively assign theoretical states to experimentally reported charmonium-like signals such as X(3872), Zc(3900), X(3960), X(4350), X(4685) and X(4700). They can be well identified as hadronic molecules;however, other exotic components which involve, for instance, hidden-color channels or diquark-antidiquark structures play a considerable role. Meanwhile, two resonances are obtained at 4.04 GeV and 4.14 GeV which may be compatible with experimental data in the energy interval 4.0−4.2 GeV. Furthermore, the X(3940) and X(4630) may be identified as color compact tetraquark resonances. Finally, we also find few resonance states in the energy interval from 4.5 GeV to 5.0 GeV, which would be awaiting for discovery in future experiments. Copyright © 2023, The Authors. All rights reserved.

关键词： Germanium alloys

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Hidden-charm pentaquarks with strangeness in a chiral quark model

arXiv

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arXiv 2023年

The LHCb collaboration has recently announced the discovery of two hidden-charm pentaquark states with also strange quark content, Pcs(4338) and Pcs(4459);its analysis points towards having both hadrons isospin equal to zero and spin-parity quantum numbers 21 − and 32−, respectively. We perform herein a systematical investigation of the qqscc¯ (q = u, d) system by means of a chiral quark model, along with a highly accurate computational method, the Gaussian expansion approach combined with the complex-scaling technique. Baryon-meson configurations in both singlet- and hidden-color channels are considered. The Pcs(4338) and Pcs(4459) signals can be well identified as molecular bound states with dominant components ΛJ/ψ (60%) and ΞcD (23%) for the lowest-energy case and ΞcD∗ (72%) for the highest-energy one. Besides, it seems that some narrow resonances can be also found in each allowed I(JP)-channel in the energy region of 4.6 − 5.5 GeV, except for the 1(21 −) where a shallow bound state with dominant Ξ∗cD∗ structure is obtained at 4673 MeV with binding energy EB = −3 MeV. These exotic states are expected to be confirmed in future high energy experiments. Copyright © 2023, The Authors. All rights reserved.

关键词： Hadrons

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The q¯qs¯Q (q = u, d;Q = c, b) tetraquark system in a chiral quark model

arXiv

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arXiv 2023年

Inspired by the experimentally reported Tcs¯(2900) exotic states, the S-wave q¯qs¯Q (q = u, d;Q = c, b) tetraquarks, with spin-parity JP = 0+, 1+ and 2+, in both isoscalar and isovector sectors are systematically studied in a chiral quark model. The meson-meson, diquark-antidiquark and K-type arrangements of quarks, along with all possible color wave functions, are comprehensively considered. The four-body system is solved by means of a highly efficient computational approach, the Gaussian expansion method, along with a complex-scaling formulation of the problem to disentangle bound, resonance and scattering states. This theoretical framework has already been successfully applied in various tetra- and penta-quark systems. In the complete coupled-channel case, and within the complex-range formulation, several narrow resonances of q¯qs¯c and q¯qs¯b systems are obtained in each allowed I(JP)-channels. Particularly, the Tcs¯(2900) is well identified as a I(JP) = 1(0+) q¯qs¯c tetraquark state with a dominant molecular structure. Meanwhile, more resonances in q¯qs¯c and q¯qs¯b systems are also obtained within the energy regions 2.4 − 3.4 GeV and 5.7 − 6.7 GeV, respectively. The predicted exotic states, which are an indication of a richer color structure when going towards multiquark systems beyond mesons and baryons, are expected to be confirmed in future high-energy particle and nuclear experiments. Copyright © 2023, The Authors. All rights reserved.

关键词： Germanium alloys

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Bose–Einstein condensation in one-dimensional systems with short-range correlated disordered on-site potentials

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The European Physical Journal B 2022年第8期95卷 1-8页

作者： Shi, Wanwan Tong, Peiqing Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing People’s Republic of China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing People’s Republic of China Nanjing Normal University Taizhou College Taizhou People’s Republic of China

We study Bose–Einstein condensation (BEC) in one-dimensional tight-binding systems with two kinds of short-range correlated disordered on-site energy sequences (OSESs). One is the chaotic sequence generated by the modified Bernoulli map, the other is the random-dimer sequence. For these two kinds of short-range correlated systems, we consider binary and non-binary versions of sequences. It is found that BEC can occur in these systems at finite temperature and their transition temperatures ( $$T_{C}s$$ ) increase with the potential strength w. Moreover, the $$T_{C}s$$ of the systems with non-binary OSESs are greater than those of the binary ones. And the $$T_{C}$$ increases with the correlation parameter B ( $$0

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