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SSRN 2024年

作者： Zhang, Baidu Qiu, Wei Liao, Xiangbiao He, Linghui Ni, Yong CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Anhui Hefei230026 China Advanced Research Institute of Multidisciplinary Science Beijing Institute of Technology Beijing100081 China

The effects of out-of-plane deformation on atomic relaxation in twisted van der Waals bilayers are investigated by comprehensive multiscale modeling and simulations. The model integrates the DFT-informed generalized stacking-fault energy for interlayer interaction between layers and the Föppl–von Kármán plate theory for elastic energy in each layer with minimization of the total free energy for atomic relaxation governed by a gradient flow method. Our simulation results elucidate twist-angle dependent moiré pattern, strain field, tortional displacement field and stacking domain structures, in good agreement with recent experimental observations. In particular, we derive the strain soliton solution at a small twist angle and the elastic solution at a large twist angle for the reconstructed van der Waals bilayer with out-of-plane deformation. These results show that out-of-plane deformation not only narrows the strain soliton width but also induces substantial alterations in the strain field, local rotation, and stacking structures. Our findings reveal the pivotal role played by out-of-plane deformation in the atomic relaxation of twisted van der Waals bilayers, particularly at smaller twist angles. The intricate interplay between in-plane atomic relaxation and out-of-plane deformation provides opportunities for strain engineering in twisted van der Waals bilayers. © 2024, The Authors. All rights reserved.

关键词： Atoms

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Design of Conical Equiangular Spiral Antenna with Wide Bandwidth and High Gain 4

Design of Conical Equiangular Spiral Antenna with Wide Bandw...

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4th International Applied Computational Electromagnetics Society Symposium in China, ACES-China 2021

作者： Zong, Liping Zong, Xianzheng Nie, Zaiping Wang, Youcheng Jiang, Peng School of Electronic Science and Engineering UESTC Chengdu China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing Electro-Mechanical Engineering Institute Beijing China

ISBN: (纸本)9781733509619

In this paper, an ultra-wideband conical equiangular spiral antenna has been designed. The presented antenna covers an operating bandwidth of f-{0}-10f-{0}. In the design, by loading absorbing materials, the voltage standing wave ratio (VSWR) of the antenna in the low frequency is improved, and the addition of metal cone structure increases the gain of high frequency, which makes the antenna performance improved in the whole band. © 2021 Applied Computational Electromagnetics Society (ACES).

关键词： Spiral antennas

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Adaptive radar detection of subspace-based distributed target in power heterogeneous clutter

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arXiv 2024年

作者： Xiao, Daipeng Liu, Weijian Liu, Jun Dai, Lingyan Fang, Xueli Ge, Jianjun Wuhan Electronic Information Institute Wuhan430019 China Department of Electronic Engineering and Information Science University of Science and Technology of China Hefei230027 China Key Laboratory of Complex Aviation Simulation System Beijing100076 China Information Science Academy China Electronics Technology Group Corporation Beijing100041 China

This paper investigates the problem of adaptive detection of distributed targets in power heterogeneous clutter. In the considered scenario, all the data share the identical structure of clutter covariance matrix, but with varying and unknown power mismatches. To address this problem, we iteratively estimate all the unknowns, including the coordinate matrix of the target, the clutter covariance matrix, and the corresponding power mismatches, and propose three detectors based on the generalized likelihood ratio test (GLRT), Rao and the Wald tests. The results from simulated and real data both illustrate that the detectors based on GLRT and Rao test have higher probabilities of detection (PDs) than the existing competitors. Among them, the Rao test-based detector exhibits the best overall detection performance. We also analyze the impact of the target extended dimensions, the signal subspace dimensions, and the number of training samples on the detection performance. Furthermore, simulation experiments also demonstrate that the proposed detectors have a constant false alarm rate (CFAR) property for the structure of clutter covariance matrix. © 2024, CC BY.

关键词： Radar clutter

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Forming Circle Formations of Multi-agent systems Under Actuator Faults 5th

Forming Circle Formations of Multi-agent Systems Under Actu...

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5th Chinese Conference on Swarm Intelligence and Cooperative Control, CCSICC 2021

作者： Liu, Jiajun Ru, Xinfeng Xia, Weiguo Wang, Chen China National Aeronautical Radio Electronic Research Institute and National Key Laboratory of Science and Technology on Avionics System Integration Shanghai China Key Laboratory of Intelligent Control and Optimization for Industrial Equipment of Ministry of Education and School of Control Science and Engineering Dalian University of Technology Dalian China National Engineering Research Center of Software Engineering and the State Key Laboratory of Turbulence and Complex Systems Intelligent Biomimetic Design Lab College of Engineering Peking University Beijing China

ISBN: (纸本)9789811939976

A distributed fault-tolerant formation control law is designed in this paper for multi-agent systems under external disturbances and actuator faults including time-varying loss of effectiveness faults. The initial position of each agent is already on a circle and the control purpose is to form a desired formation on this circle. Based on this local information, a distributed adaptive formation control law is designed by employing the congelation of variables method to deal with time-varying actuator faults. Finally, a simulation example is given to verify the effectiveness of the adaptive fault-tolerant control design method. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Multi agent systems

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A Stable and Symmetric FDTD Subgridding Method with Arbitrary Grid Ratio

A Stable and Symmetric FDTD Subgridding Method with Arbitrar...

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Antennas and Propagation Society International Symposium

作者： Langran Deng Ningbo Gong Guijie Diao Shunchuan Yang Research Institute for Frontier Science Beihang University Beijing China Beijing Electro-mechanical Engineering Institute Beijing China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory China

A stable and symmetric finite-difference time-domain (FDTD) subgridding method is proposed to effectively and accurately solve the three-dimensional electromagnetic prob-lems. The linear interpolation coefficient (LIC) and the length cutoff coefficient (LCC) are carefully designed to guarantee the stability of the proposed method. In addition, the proposed method is applicable to arbitrary grid ratios and nested meshes. A practical multiscale example is used to validate its accuracy and efficiency.

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A Micromagnetic-Mechanically Coupled Phase-Field Model for Fracture and Fatigue of Magnetostrictive Alloys

SSRN

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SSRN 2024年

作者： Sun, Shen Gong, Qihua Ni, Yong Yi, Min Nanjing210016 China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Hefei230026 China

Magnetostrictive alloys are usually brittle materials with micromagnetic structures. Their structural reliability and durability depend on the complex micromagnetic-mechanical coupling at smaller length scales encompassing the evolution of micromagnetic structures. Herein we propose a micromagnetic-mechanically coupled phase-field model for fracture and fatigue behavior of magnetostrictive alloys with evolution of the micromagnetic structure. The thermodynamically-consistent model is derived from microforce theory, laws of thermodynamics, and Coleman–Noll analysis. The evolution of crack phase-field and magnetization-vector order parameters that are fully coupled is governed by history field dependent Allen–Cahn and Landau–Lifshitz–Gilbert equations, respectively. The model is extended to fatigue by introducing a degradation prefactor for the fracture energy as a function of positive elastic energy. One-dimensional analyses are then presented to anatomize the crack driving forces in terms of fully coupled micromagnetic-mechanical and pure mechanical driving force. We demonstrate the model capabilities by finite-element numerical studies on the micromagnetic domain evolution during the crack propagation and the influence of external magnetic field for type-I, type-II, and three-point bending fracture, as well as for the fracture of a single-edge notched specimen with an elliptical inclusion. The simulation result shows that depending on how micromagnetic domains are switched under micromagnetic-mechanical coupling, the magnetic field can enhance or decrease the critical load. In the presence of inclusion with larger fracture toughness, a crack is found to nucleate in the tri-junction of multi-domain micromagnetic structure owing to the high elastic strain around the tri-junction point. It is further found that a suitable magnetic field promoting magnetization-vector rotation around the crack tip could remarkably improve the fracturing load and fatigue life. The resul

关键词： Magnetic fields

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A Provably Stable SBP-SAT FDTD Subgridding Method without Modifying Yee's Grids

A Provably Stable SBP-SAT FDTD Subgridding Method without Mo...

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Antennas and Propagation Society International Symposium

作者： Yuhui Wang Guijie Diao Hong Ni Shunchuan Yang Research Institute for Frontier Science Beihang University Beijing China Beijing Electro-mechanical Engineering Institute Beijing China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory China

A stable finite-difference time-domain (FDTD) sub-grid ding method using the summation-by-parts simultaneous approximation term (SBP-SAT) technique is proposed. To meet the SBP properties and keep Yee's grids unchanged, the projection operators are carefully designed to extrapolate fields on the boundaries. Then, the SATs are used to weakly enforce the boundary conditions between multiple mesh blocks with different mesh sizes. Therefore, its long-term stability is theoretically guaranteed. An iris filter is simulated to validate the effectiveness of the proposed method. Results show that the proposed SBP-SAT FDTD subgridding method is stable, accurate and efficient.

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A coevolutionary framework of business-IT alignment via the lens of enterprise architecture

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Journal of systems Engineering and Electronics 2020年第5期31卷 983-995页

作者： LIN Menglong YI Shuanghui ZHANG Mengmeng CHEN Tao CHEN Honghui ZHANG Xiaoxue Science and Technology on Information Systems Engineering Laboratory National University of Defense TechnologyChangsha 410072China National Key Laboratory for Complex System Simulation Academy of Military SciencesBeijing 100000China

Due to the turbulent external business environment, the complexity of internal relations of the organization and the emergence of subversive IT roles, the business-IT alignment(BITA)has become increasingly difficult. The unsuccessful realization of BITA will lead to the waste of organizational resources, the reduction of return on investment and eventually the loss of competitive advantage. In recent years, coevolution has received widespread attention due to its ability to describe the dynamic relationship between IT and business. Multiple principles such as quickening learning action loops and adopt suitable organizing principles for achieving business and IT coevolution(BITC) are obtained. However, the continuous BITC is still hard to be achieved because of the lack of complete BITC management. This paper focuses on the management process of the BITC and how to perform it gradually. A coevolution framework combines the enterprise architecture(EA) approach with the coevolution analysis is proposed, which contains the design of EA, the sensing and governance of the misalignment and the procedure of the EA misalignment *** steps for the governance and prevention of misalignment are discussed in particular. Through comparison with the principles,characteristics and methods of coevolution in the literature, the proposed framework is evaluated. The results show that the proposed framework is effective for BITC implementation.

关键词： business-IT alignment(BITA) coevolution misalignment governance misalignment prevention enterprise architecture

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Effectiveness Evaluation of Space-based Information system based on Improved SVR 5

Effectiveness Evaluation of Space-based Information System b...

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5th IEEE Information technology, Networking, Electronic and Automation Control Conference, ITNEC 2021

作者： Han, Chi Xiong, Wei Jian, Ping Aerospace Engineering University Aerospace Information Institute Beijing China Aerospace Engineering University Science and Technology on Complex Electronic System Simulation Laboratory Beijing China

ISBN: (纸本)9781665415989

The evaluation of effectiveness of space-based information system (SIS) is of great significance for modern warfare in integrated operations. In view of characteristics of complex impact factors, small number of samples and strong nonlinearity of effectiveness evaluation, support vector regression (SVR) is adopted to evaluate effectiveness. At the same time, cuckoo search optimizer (CSO) is introduced to optimize the three parameters of SVR. The simulation results indicate that improved SVR has higher accuracy than the traditional SVR and BP neural network, and can effectively evaluate the effectiveness of SIS. © 2021 IEEE.

关键词： Vector spaces

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Rudder Health Monitoring and Data Visualization Based on Feature Extraction 10

Rudder Health Monitoring and Data Visualization Based on Fea...

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10th IEEE Data Driven Control and Learning systems Conference, DDCLS 2021

作者： Zhou, Yajing Sun, Mingwei Hao, Mingrui Chen, Zengqiang College of Artificial Intelligence Nankai University Tianjin300350 China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing100074 China

ISBN: (纸本)9781665424233

In order to monitor the health status of the rudder, this paper proposes a health monitoring method based on deep neural network through feature extraction. First, sufficient samples are obtained by data preprocessing. Then the feature dimension is reduced by using autoencoder, and the health monitoring can be carried out by combining with Softmax classifier. After proper tuning and comparison, proper network structure parameters can be obtained. Two kinds of images can be plotted by using the feature extraction of encoder to provide explicit contrast between the normal and abnormal rudders. The effectiveness of the proposed method can be demonstrated by numerical simulations. © 2021 IEEE.

关键词： Visualization

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