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Analysis and optimizations of macro-pulse performances for a constructed high-power beam injector with a compact layout

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Nuclear Engineering and technology 2025年第10期57卷

作者： H. Hu Y. Wang H.J. Xu Y.F. Zeng T.N. Hu H.M. Wang G.Y. Feng Y.J. Pei State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China Chengdu Aircraft Design & Research Institute Aviation Industry Corporation of China Chengdu 610091 China National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 China

The performance of terahertz (THz) radiation from free electron lasers (FEL) depends on the consistency of electron bunches within the macro-pulse, not just the properties of individual bunches. In accelerator-based injectors, bunch-to-bunch deviations often arise due to transient beam loading effects. This study investigates the impact of such transient responses on macro-pulse inconsistencies by combining theoretical analysis and particle simulations, using the FEL injector at Huazhong University of science and technology (HUST) as a case study. The goal is to optimize macro-pulse performance without requiring additional equipment or facility upgrades. To achieve this, an improved multi-objective optimization algorithm, NSGA-III, is introduced to optimize RF injection timing and phase settings, targeting energy and phase consistency within the macro-pulse and stable energy output. The approach is validated through extensive virtual simulations, which demonstrate its effectiveness in providing optimal initial settings for the HUST-FEL injector's macro-pulse. Subsequent online experiments conducted on this injector have preliminarily validated the reliability of the proposed method as well. The results are applicable to other multi-bunch/macro-pulse injectors, offering a cost-effective solution for efficient beam commissioning and engineering implementation.

关键词： Beam injector Transient beam loading Free electron laser linac Beam dynamics

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Exploration of the LHCb states and possible resonances in a unitary coupled-channel model

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The European Physical Journal C 2024年第7期84卷 1-10页

作者： Shen, Chao-Wei Rönchen, Deborah Meißner, Ulf-G. Zou, Bing-Song Wang, Yu-Fei Institute for Advanced Simulation (IAS-4) Forschungszentrum Jülich Jülich Germany Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics Universität Bonn Bonn Germany Tbilisi State University Tbilisi Georgia Department of Physics Tsinghua University Beijing China CAS Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing China School of Physics University of Chinese Academy of Sciences (UCAS) Beijing China School of Nuclear Science and Technology University of Chinese Academy of Sciences (UCAS) Beijing China

We extend our previous study of the interactions of $$\bar{D}^{(*)} \Lambda _c - \bar{D}^{(*)}\Sigma _c^{(*)}$$ within an analytic, unitary, coupled-channel approach by including the $$J/\psi p$$ channel and performing fits to the $$J/\psi p$$ invariant mass distributions in the $$\Lambda _b^0 \rightarrow J/\psi p K^-$$ decay by the LHCb Collaboration. We take into account the contributions of t-channel pseudoscalar and vector meson exchanges and u-channel baryon exchanges in this work, and a series of bound states and resonances with different spin-parities are dynamically generated. According to the results, four states have a significant impact on the physical observables, with two having a spin-parity of $$1/2^-$$ and the other two having $$3/2^-$$ . These states can be associated with the LHCb hidden-charm pentaquarks. We further provide the coupling strength between each pole and different channels, which provides some insights on how to search for them in future experiments. Moreover, we also search for poles in higher partial waves up to $$J=7/2$$ and find indications for the existence of several states with larger widths.

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Corrigendum to “Strong convergence theorem of a new modified Bregman extragradient method to solve fixed point problems and variational inequality problems in general reflexive Banach spaces [Communications in Nonlinear science and Numerical simulation, 135, (2024): CNSNS 108051]

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Communications in Nonlinear science and Numerical simulation 2024年 138卷

作者： Huilin Tan Qian Yan Gang Cai Qiaoli Dong School of Mathematical Sciences Chongqing Normal University College of Sciences Chongqing University of Technology Tianjin Key Laboratory for Advanced Signal Processing and College of Science Civil Aviation University of China

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MoO 3 -MoC/ [email protected] coupled heterostructures with strong connections and abundant interfaces for electromagnetic wave absorption

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Colloids and Surfaces A: Physicochemical and Engineering Aspects 2023年 668卷

作者： Yichao Yin Xiaojun Zeng Lei Xia Guangjie Xiong Hang Zhang Guoke Wei Aviation Key Laboratory of Science and Technology on Advanced Surface Engineering AVIC Manufacturing Technology Institute Beijing 100024 China School of Materials Science and Engineering Jingdezhen Ceramic University Jingdezhen 333403 China

Improving the electromagnetic wave (EMW) absorption capability at the thin thickness of heterostructures is critical but remains a great challenge. Here, we propose a MoO 3 @ZIF-67 core-shell heterostructure derived molybdenum trioxide- molybdenum carbide/ [email protected] carbon (MoO 3 -MoC/ [email protected] ) coupled heterostructure with a one-dimensional (1D) short rod-like structure for EMW absorption. A strong connection is constructed between [email protected] nanoparticles (NPs) and MoO 3 -MoC specie due to the pyrolysis strategy and in situ reaction between MoO 3 nanobelts and ZIF-67 rhombic dodecahedrons . The abundant heterointerfaces between N-doped carbon (NC) and metallic Co, [email protected] NPs and MoC species, [email protected] NPs and MoO 3 nanobelts, as well as MoC and MoO 3 nanobelts improve the interfacial polarization. Abundant defects, such as N heteroatoms and oxygen vacancies , are also established in the MoO 3 -MoC/ [email protected] coupled heterostructure. As a result, the MoO 3 -MoC/ [email protected] coupled heterostructure inherits excellent EMW absorption performance with a reflection loss ( R L ) value of − 64.3 dB at a thickness of 3.875 mm, outperforming many advanced EMW absorbers. This work shows the great potential of strong connections and abundant interfaces in heterostructure for improvements of EMW absorbers.

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Real-time characterization of VOC exposure in a few new residential apartments in Beijing 16

Real-time characterization of VOC exposure in a few new resi...

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16th Conference of the International Society of Indoor Air Quality and Climate: Creative and Smart Solutions for Better Built Environments, Indoor Air 2020

作者： Liu, Yingjun Xie, Di Qiu, Jia Li, Yatai Qu, Yuekun Liu, Ying Zhu, Tong Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering Peking University Beijing100871 China Beijing Innovation Center for Engineering Science and Advanced Technology Peking University Beijing100871 China

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Global Dynamics and Optimal Design of a New Highly Efficient Nonlinear Energy Sink Based on Magnetic-Elastic Impacts with Negative Stiffness

Research Square

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Research Square 2021年

作者： Li, Shuangbao Wang, Tingting Chen, Jianen Research Institute of Science and Technology Innovation Civil Aviation University of China Tianjin300300 China College of Science Civil Aviation University of China Tianjin300300 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China

A new highly efficient elastic-impact bistable nonlinear energy sink (EI-BNES) based on magnetic-elastic impacts with negative stiffness and bistability is proposed and optimized through global dynamical analysis. The EI-BNES has better robustness and higher energy dissipation rates with nearly more than 96.5% for broadband impulsive excitations than the traditional cubic NESs and single bistable NESs. The structure of negative stiffness impacts is realized by reasonable layout of permanent ring magnets and springs. A two-degree-of-freedom (two-DOF) elastic-impact system is established to describe the coupled nonlinear interaction between the main structure and the attached EI-BNES. A global Melnikov reduction analysis (GMRA) is proposed to study global dynamics and homoclinic bifurcations of the reduced two-dimensional subsystem, which is used to explain the mechanism of nonlinear targeted energy transfer (TET) and detect the threshold of impulsive amplitudes of EI-BNES for in-well and compound motions between in-well and cross-well resonance responses. A special type of saddle-center equilibrium points is also found in the non-smooth system of the EI-BNES and can be used to effectively increase the energy dissipation rates. The optimal design criterion of the tuned EI-BNES for better dissipation performance is also first discussed based on the GMRA and numerical techniques for calculating the Melnikov function of the non-smooth systems. The effectiveness of the analytical GMRA is also verified by numerical simulations. © 2021, CC BY.

关键词： Stiffness

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Current-driven magnetoresistance in van der Waals spin-filter antiferromagnetic tunnel junctions with MnBi2Te4

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Physical Review Applied 2023年第4期20卷 044056-044056页

作者： Lishu Zhang Hui Li Yanyan Jiang Zishen Wang Tao Li Sumit Ghosh Peter Grünberg Institut (PGI-1) and Institute for Advanced Simulation (IAS-1) Forschungszentrum Jülich Jülich 52428 Germany Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials Ministry of Education Shandong University Jinan 250061 China Department of Physics National University of Singapore Singapore 117542 Singapore Department of Physics Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong 999077 China Institute of Physics Johannes Gutenberg-University Mainz Mainz 55128 Germany

The field of two-dimensional magnetic materials has paved the way for the development of spintronics and nanodevices with other functionalities. Utilizing antiferromagnetic materials, in addition to layered van der Waals (vdW) ferromagnetic materials, has garnered significant interest. In this work, we present a theoretical investigation of the behavior of MnBi2Te4 devices based on the nonequilibrium Green’s function method. Our results show that the current-voltage (I-V) characteristics can be influenced significantly by controlling the length of the device and bias voltage and thus allow us to manipulate the tunneling magnetoresistance (TMR) with an external bias voltage. This can be further influenced by the presence of the boron nitride layer, which shows significantly enhanced TMR by selectively suppressing specific spin channels for different magnetic configurations. By exploiting this mechanism, the observed TMR value reaches up to 3690%, which can be attributed to the spin-polarized transmission channel and the projected local density of states. Our findings on the influence of structural and magnetic configurations on the spin-polarized transport properties and TMR ratios give the potential implementation of antiferromagnetic vdW layered materials in ultrathin spintronics.

关键词： Spin polarization Transport phenomena Tunneling magnetoresistance Antiferromagnets Magnetic tunnel junctions Van der Waals systems Density functional calculations Nonequilibrium Green's function

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Walk the Line: The Role of Gender and Culture on the Movement Patterns of Pedestrians Based on a Multicultural Study

SSRN

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SSRN 2024年

作者： Chraibi, Mohcine Feliciani, Claudio Haghani, Milad Jia, Xiaolu Ma, Jian Institute of Advanced Simulation Forschungszentrum Jülich GmbH Wilhelm-Johnen-Straße Jülich52428 Germany School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan Research Center for Advanced Science and Technology The University of Tokyo 4-6-1 Komaba Meguro-ku Tokyo153-8904 Japan Sydney SydneyNSW2052 Australia Beijing Key Laboratory of Traffic Engineering Beijing University of Technology 100 Pingleyuan Chaoyang District Beijing100124 China School of Transportation and Logistics Southwest Jiaotong University 999 Xi’an Road Pidu District Sichuan Chengdu611756 China

Experimental work has opened new avenues for studying crowd behavior under well-controlled conditions with desirable levels of measurement accuracy. However, unlike many other areas of behavioral science, little attention has been paid to how reproducible and transferable crowd phenomena are between different populations. As such, there is only limited knowledge about how universal and generalizable experimental observations on crowd behavior *** research explores how gender and culture impact pedestrian dynamics in single-file movement, a topic previously studied in isolation through disjointed and varied experiments. Here, for the first time, and as an attempt to investigate external validity and generalizability across cultures, we conduct the same experiment in five different countries. Each experiment examines the effects of varying gender compositions on single-file pedestrian *** observed consistent effects of different gender compositions on pedestrian movement across countries, with no significant deviations in the fundamental diagrams, especially in the bounded regime. Although there was some variability in acceleration behavior across countries. Interaction levels, clustering behavior, and pedestrian spacing patterns remained consistent between different gender compositions and countries. These results suggest that, while the behavior of collective motion varies by culture and gender composition, most aspects of pedestrian movement exhibit universal traits. Understanding these variations and commonalities can allow for better infrastructure design and planning tailored to the population of interest. © 2024, The Authors. All rights reserved.

关键词： Behavioral research

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An Efficient Plasma Regeneration of As-Poisoned V2O5-Based Catalyst for Simultaneous Poison Removal and Activity Enhancement

SSRN

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SSRN 2024年

作者： Yin, Yong Li, Kezhi Jiang, Si Peng, Yue Zhu, Tianle Sun, Yifei Li, Junhua Li, Xiang School of Energy and Power Engineering Beihang University Beijing100191 China Institute of Engineering Technology Sinopec Catalyst Co. Ltd. Beijing101111 China State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing100084 China School of Materials Science and Engineering Beihang University Beijing100191 China School of Environmental Science and Engineering Hainan University Haikou570228 China Research Center for Advanced Energy and Carbon Neutrality Beihang University Beijing100191 China

Regeneration of highly toxic Arsenic (As) poisoned SCR catalysts is a huge challenge, because the strong interactions between As and the active component often leads to the loss or damage of active sites during the regeneration process. Herein, we develop a low-temperature plasma regeneration method that not only selectively removes As but also preserves the active components for commercial V2O5-WO3/TiO2 catalyst. More intriguingly, the catalyst after plasma regeneration achieves a significant catalytic performance enhancement, far surpassing the fresh V2O5-WO3/TiO2 catalyst. Under optimized regeneration conditions, the regenerated catalyst exhibits an As removal rate exceeding 99.5 ± 0.2% within 240 s, and a TOF value that was 11.1 and 2.4 times of the poisoned and fresh catalyst. Structural characterization reveals that the enhanced intrinsic activity of regenerated catalyst mainly stems from the As complete removal and subsequent transformation of monomeric VOx species into polymeric ones under H2 plasma environment. Multiple spectroscopic monitoring techniques unveil three stages in the plasma treatment process: (1) As reduction and removal, (2) surface polymerization of VOx species, and (3) vanadium embedded into TiO2 lattice. At low temperatures, the well regenerated catalysts with abundant polymeric VOx facilitate the nitrate-assisted dehydrogenation of adsorbed NH3 to key NH2 intermediates, thereby achieving superior NH3-SCR catalytic performance. This study not only provides a rapid regeneration strategy for poison selective separation from spent catalysts but also offers new insights into the precise control and design of active sites. © 2024, The Authors. All rights reserved.

关键词： Temperature

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DeePMD-kit v3: A Multiple-Backend Framework for Machine Learning Potentials

arXiv

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arXiv 2025年

作者： Zeng, Jinzhe Zhang, Duo Peng, Anyang Zhang, Xiangyu He, Sensen Wang, Yan Liu, Xinzijian Bi, Hangrui Li, Yifan Cai, Chun Zhang, Chengqian Du, Yiming Zhu, Jia-Xin Mo, Pinghui Huang, Zhengtao Zeng, Qiyu Shi, Shaochen Qin, Xuejian Yu, Zhaoxi Luo, Chenxing Ding, Ye Liu, Yun-Pei Shi, Ruosong Wang, Zhenyu Bore, Sigbjørn Løland Chang, Junhan Deng, Zhe Ding, Zhaohan Han, Siyuan Jiang, Wanrun Ke, Guolin Liu, Zhaoqing Lu, Denghui Muraoka, Koki Oliaei, Hananeh Singh, Anurag Kumar Que, Haohui Xu, Weihong Xu, Zhangmancang Zhuang, Yong-Bin Dai, Jiayu Giese, Timothy J. Jia, Weile Xu, Ben York, Darrin M. Zhang, Linfeng Wang, Han School of Artificial Intelligence and Data Science Unversity of Science and Technology of China Hefei China AI for Science Institute Beijing100080 China DP Technology Beijing100080 China Academy for Advanced Interdisciplinary Studies Peking University Beijing100871 China State Key Lab of Processors Institute of Computing Technology Chinese Academy of Sciences Beijing100871 China University of Chinese Academy of Sciences Beijing China Baidu Inc. Beijing China Department of Computer Science University of Toronto TorontoON Canada Department of Chemistry Princeton University PrincetonNJ08540 United States University of Chinese Academy of Sciences Beijing100871 China State Key Laboratory of Physical Chemistry of Solid Surfaces iChEM College of Chemistry and Chemical Engineering Xiamen University Xiamen361005 China College of Integrated Circuits Hunan University Changsha410082 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Center for Smart Materials and Device Integration School of Material Science and Engineering Wuhan University of Technology Wuhan430070 China College of Science National University of Defense Technology Changsha410073 China Hunan Key Laboratory of Extreme Matter and Applications National University of Defense Technology Changsha410073 China ByteDance Research Beijing100098 China Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo315201 China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Beijing100049 China Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education College of Chemistry Beijing Normal University Beijing100875 China Department of Geosciences Princeton University PrincetonNJ08544 United States Department of Applied Physics and Applied Mathematics Columbia University New YorkNY10027 United States IKKEM Fujian Xiamen361005 China Graduate

In recent years, machine learning potentials (MLPs) have become indispensable tools in physics, chemistry, and materials science, driving the development of software packages for molecular dynamics (MD) simulations and related applications. These packages, typically built on specific machine learning frameworks such as TensorFlow, PyTorch, or JAX, face integration challenges when advanced applications demand communication across different frameworks. The previous TensorFlow-based implementation of DeePMD-kit exemplified these limitations. In this work, we introduce DeePMD-kit version 3, a significant update featuring a multi-backend framework that supports TensorFlow, PyTorch, JAX, and PaddlePaddle backends, and demonstrate the versatility of this architecture through the integration of other MLPs packages and of Differentiable Molecular Force Field. This architecture allows seamless backend switching with minimal modifications, enabling users and developers to integrate DeePMD-kit with other packages using different machine learning frameworks. This innovation facilitates the development of more complex and interoperable workflows, paving the way for broader applications of MLPs in scientific research. Copyright © 2025, The Authors. All rights reserved.

关键词： Molecular dynamics

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