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Large electrical strain in lead-free K_(0.5)Na_(0.5)NbO_(3)-based ceramics by heterovalent doping

Journal of Materiomics 2023年第5期9卷 959-970页

作者： Xiangjian Wang Jun Wang Wenping Geng Guohua Dong Brahim Dkhil Xiaojie Lou Department of Information Engineering Quzhou College of TechnologyQuzhou324000China Frontier Institute of Science and Technology and State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China Science and Technology on Electronic Test and Measurement Laboratory North University of ChinaTaiyuan030051China Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education&International Center for Dielectric ResearchXi'an Jiaotong UniversityXi'an710049China Applied Physics Division of Materials ScienceDepartment of Engineering Sciences and MathematicsLuleåUniversity of TechnologySE-97187LuleåSweden Laboratoire Structures Proprietes et Modelisation des SolidesUniversite Paris SaclayCentraleSupelecCNRS-UMR8580Grande Voie des VignesCh^atenay MalabryCedex92295France

Heterovalent doped(K_(0.48-0.07)xNa_(0.52-0.43)xBi_(0.5)x)(Nb_(0.95-0.95x)Sb_(0.05-0.05x)Zrx)O_(3)ceramics were fabricated using conventional solid-state ***,the phase structures,dielectric,ferroelectric,and electricstrain properties were *** compositions were tuned to be located at polymorphic phase boundary with increasing heterovalent Bi3t and Zr4t doping levels.A large strain of 0.19%was obtained at relatively low electric fields of 30 kV/cm in the composition of x=*** normalized large-signal d33*values were approximately 633 pm/V under a low driving electric field of 30 kV/cm,which were comparable or larger than the values reported for other lead-free *** large strains obtained can be attributed to the formation of nanodomains and high-density domain walls,which were confirmed by the observations of domain morphology using transmission electron microscopy(TEM)*** temperature stability of the strain properties of the x=0.04 sample could be ascribed to the sluggish behaviour for the local structural heterogeneity in heterovalent-ion doped KNN *** simulations revealed that the Zr^(4t)produce the local stress at the BO6 octahedra and Bi3t could yield off-centering of AO12 ployhedron due to the nature of Bi 6s lone pair electrons,which induced lattice expansion and local distortions in the *** local displacements are strongly anisotropic in heterovalent-ion doped *** is believed that random local fields exist in these compositions owing to the eixstence of charge *** heterovalent doping of Bi^(3t)and Zr^(4t)could destory simultaneously the orthorhombic symmetry and the short-range ferroelecctric order,leading to the formation of complex nanodomains and local structral *** doping may,therefore,offer a new avenve to design novel K0.5Na0.5NbO3(KNN)-based materials for their mutifunctional applications.

关键词： Lead-free Strain Heterovalent doping Local structure Nanodomain

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Htem: High-Throughput Toolkit for Elasticity Modeling

SSRN

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SSRN 2025年

作者： Yang, Zhen Xian, Jiawei Xu, Yuanji Lin, De-Ye Wang, Qingchun Gao, Xingyu Tian, Fuyang Song, Haifeng Institute for Applied Physics University of Science and Technology Beijing Beijing100083 China National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing100094 China CAEP Software Center for High Performance Numerical Simulation Institute of Applied Physics and Computational Mathematics Beijing100094 China

The elasticity under varying temperatures and pressures is particularly significant for understanding mechanical properties and structural phase transitions. Consequently, there is an increasing demand for tools capable of determining elasticity across wide temperature and pressure ranges, either numerically or analytically. We propose HTEM, a comprehensive toolkit that automates the workflow for input generation, elastic calculations, modeling, and visualization within an integrated framework. HTEM performs simulations with four computational modes, allowing users to balance accuracy and efficiency. It incorporates a semi-analytic model for robust, high-precision elastic modeling with finite data combinations, even using sparse elasticity at high temperatures. To validate the workflows of calculation and modeling, we perform HTEM to study the elasticity of Si across wide temperature and pressure ranges. Results show the high precision and high efficiency of HTEM. And modeling mitigates noise from constant pressure ensemble simulations. Furthermore, HTEM provides detailed visualizations of elasticity and its anisotropy as functions of temperature and pressure, providing comprehensive insights into how the intrinsic properties of materials evolve under varying conditions. © 2025, The Authors. All rights reserved.

关键词： Elasticity

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On the metric resolvent: nonexpansiveness, convergence rates and applications

arXiv

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arXiv 2021年

作者： Xue, Feng National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China

In this paper, we study the nonexpansive properties of metric resolvent, and present a convergence rate analysis for the associated fixed-point iterations (Banach-Picard and Krasnosel’skii-Mann types). Equipped with a variable metric, we develop the global ergodic and non-ergodic iteration-complexity bounds in terms of both solution distance and objective value. A byproduct of our expositions also extends the proximity operator and Moreau’s decomposition identity to arbitrary variable metric. It is further shown that many classes of the first-order operator splitting algorithms, including alternating direction methods of multipliers, primal-dual hybrid gradient and Bregman iterations, can be expressed by the fixed-point iterations of a simple metric resolvent, and thus, the convergence can be analyzed within this unified *** Codes 68Q25, 47H05, 90C25, 47H09 Copyright © 2021, The Authors. All rights reserved.

关键词： Iterative methods

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Real-Time Path Planning based on the Lock Loss Model

Real-Time Path Planning based on the Lock Loss Model

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Xun Luo Li Liu Xin Liu National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing China China Academy of Launch Vehicle Technology Beijing China

A new method of aircraft low altitude penetration is proposed with temporal constraints that allow periods of high observability interspersed with periods of low observability. The aircraft’s RCS character is simplified into the “bow-tie” distribution, then the aircraft can dynamically adjust its yaw angle to minimize the risk from the radars. According to the modified Lock Loss model and the TWS(Track While Scan) radar work flow, and real-time evaluating model on the original path, a fast real-time path planning method is present on the situation that unexpected threats occur. An example of real-time path planning is given.

关键词： Radar cross-sections Atmospheric modeling Heuristic algorithms Airborne radar Real-time systems Path planning Safety

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A Radar Signal Modulation Recognition Algorithm Based on Multi-branch Fusion Difference

A Radar Signal Modulation Recognition Algorithm Based on Mul...

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IEEE International Conference on Electronic Information and Communication technology (ICEICT)

作者： Sisi Jiang Jingpeng Gao Zhiye Jiang Fang Ye College of Information and Communication Engineering Harbin Engineering University Haibin China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China National Key Laboratory of Underwater Acoustic Technology College of Information and Communication Engineering Harbin Engineering University Harbin China

The time-frequency images of radar modulation signals are similar at low signal-to-noise ratios, which will lead to lower recognition accuracy. This paper proposes an algorithm based on multi-branch fusion differences to identify radar modulation signals. The algorithm designs a multi-branch fusion differential module based on the attention mechanism and differential thinking, to extract time-frequency image fine-grained features and improve the Convolution Neural Network characterization ability. After that, a dual-branch differential network is proposed by combining vanilla convolution and multi-branch fusion difference module. The network can fuse global and detailed features of time-frequency images, which can achieve radar signal modulation recognition. The simulation results show that the recognition accuracy of the algorithm can reach 93.17% at 0dB. Therefore, the algorithm can obtain high recognition accuracy and has high recognition performance.

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Periodic Structures and Its Interaction to EM Wave Spectrum, Ideas From X-Ray to MW Wave

Periodic Structures and Its Interaction to EM Wave Spectrum,...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Yunhui Tang Lu Gao Ruzhi Wang Shengjun Zhang Hang Song Yuning Zhang Xia Ai Lei Xie Luting Jiao Xiaoling Zhang Jing He Jiaqi Liu Beijing University of Technology Beijing China National Key Laboratory of Science & Technology on Test Physics and Numerical Mathematics Beijing China Beijing Institute of Space Long March Vehicle Beijing China

X-ray is an important tool for characterizing materials, which is based on the idea that all crystals are composed of atoms or molecules stacking in a particular type, basically expressing as unit cell, diffracting the incident ray with a proper type. In analogue, the periodic structures which are mostly constructed artificially show special desired properties, such as the properties of grating, frequency selective surfaces, metamaterials and metasurface. In this paper, A study was done on the insight of the relation of wave interaction with periodic structures based on X-ray diffraction and control of electromagnetic waves.

关键词： Frequency selective surfaces Stacking Electromagnetic scattering Crystals X-ray diffraction Metasurfaces Computational electromagnetics

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The Role of Regional Ocean-Atmosphere Coupling in Simulating the 2020 Extreme Mei-yu Event

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Advances in Atmospheric sciences 2025年第5期42卷 904-920页

作者： Kai LI Liwei ZOU Li DAN Hui ZHENG Zhongfeng XU Jianping TANG Fuqiang YANG Wenli FEI Taotao ZHANG Chunxiang SHI Zong-Liang YANG Key Laboratory of Regional Climate and Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Key Laboratory of Meteorological Disaster(KLME) Ministry of Education&Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science&TechnologyNanjing 210044China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China School of Atmospheric Sciences Nanjing UniversityNanjing 210023China Institute of Applied Ecology Chinese Academy of SciencesShenyangLiaoning 110016China National Meteorological Information Center China Meteorological AdministrationBeijing 100081China Department of Earth and Planetary Sciences Jackson School of GeosciencesThe University of Texas at AustinAustinTX 78712USA

The Yangtze-Huaihe River Valley(YHRV)experienced a record-breaking mei-yu season during the summer of 2020,prompting investigation into the role of regional ocean-atmosphere coupling in simulating this extreme *** comparative analysis of regional ocean-atmosphere coupled(CP)and atmosphere-only(WRF)simulations,the aim of this study was to elucidate the mechanisms underlying this *** indicate that CP effectively reproduced the observed sea surface temperature spatial distribution and its daily variation during the period from 25 June to 25 July 2020,and notably reduced the wet biases over the YHRV when compared to WRF *** improvement in representation was manifested in the observed rainfall spatial distribution and daily *** wet biases simulated by WRF were associated with a stronger 200-hPa westerly jet and a more westward-positioned western North Pacific subtropical high(WNPSH)with more intense 500-hPa winds and a stronger 850-hPa ***,these biases were significantly reduced in CP *** analysis revealed that regional ocean-atmosphere coupling over the western Northwest Pacific influenced surface turbulent heat fluxes and atmospheric instability,thereby modulating the intensity and position of the WNPSH and associated circulation subsystems at different ***,adjustments in land-sea thermal contrast induced by ocean-atmosphere coupling impacted YHRV precipitation by altering East Asian circulation *** findings highlight the significant role of regional ocean-atmosphere coupling in enhancing the simulation and understanding of extreme mei-yu events over East Asia.

关键词： 2020 extreme mei-yu regional ocean-atmosphere coupling circulation systems land-sea heat contrast

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An Improved DSDV Protocol based on Link Stability with Adaptive Period for Intra-cluster Routing in High-dynamic Flying UAV Networks

An Improved DSDV Protocol based on Link Stability with Adapt...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Yiguo Zhang Lai Qian Xiaoqin Xue Wei Wang College of Computer Science Xi’an Polytechnic University Xi’an China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China

We propose a stability-based adaptive-period DSDV intra-cluster routing protocol that automatically adjusts the routing update period by the link stability among the nodes in the cluster structure, thus reducing the network overhead of the network structure in maintaining the routing table. We describe the link stability and adaptive period implementation and test the proposed routing protocol in the cluster structure based on network simulation. The implementation results show that the proposed routing protocol has better performance than the traditional DSDV routing protocol, can improve the network throughput and reduce the routing overhead in the network, and has good adaptability in the cluster with fast changing network topology.

关键词： Costs Adaptive systems Network topology Routing Throughput Computational electromagnetics Routing protocols

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Spectral–spatial attention fusion transformer for hyperspectral image classification

Spectral–spatial attention fusion transformer for hyperspec...

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IET International Radar Conference (IRC 2023)

作者： Xiangyu Ji Jingpeng Gao Geng Chen Lu Gao College of Information and Communication Engineering Harbin Engineering University Harbin People's Republic of China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing People's Republic of China

ISBN: (数字)9781837240982

In view of the limited generalization and poor local feature information modeling ability of vision transformer model(ViT) in hyperspectral image classification, a Spectral-Spatial Attention Fusion Transformer (SAFT) method for hyperspectral image classification is proposed in this paper. The proposed method includes two key modules: Spectral-Spatial Feature Extraction Module (SSFE) and Multi-Head Attention Fusion Transformer Module (MAFT). The SSFE module is a lightweight network. It contains a 3D convolution block and a 2D convolution block, which can efficiently obtain local feature information. Based on the proposed attention fusion structure, the MAFT module designs an improved transformer encoder. It improves the generalization ability of the model on the premise of obtaining global information. In this paper, two datasets of HyRANK are used for experiments. The experimental results show that this method is superior to other HSI classification methods.

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Characteristic Mode Design of Dual-Band Multistate Tunable Absorber Based on Programmable Flexible Metasurface

TechRxiv

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TechRxiv 2022年

作者： Li, Mengmeng Ning, Zihao Ding, Dazhi Ai, Xia Liu, Jiaqi Wang, Chao-Fu The Department of Communication Engineering Nanjing University of Science and Technology Nanjing China The National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China The Department of Electrical and Computer Engineering National University of Singapore Singapore

Theory of characteristic modes (TCM) is applied to the design of a programmable flexible metasurface (PFMS) to achieve its multistate tunable microwave absorption. The designed metasurface consists of two layers. The first layer is a very thin polyimide (PI), on which unit cells consisting of two trapezoidal patches symmetrical along the central bias microstrip are printed. The second layer is grounded polyvinyl chloride (PVC) substrate to maintain the flexibility of the designed structure. The TCM is used to analyze and understand the modal behavior of the unit cell, which provides clear underlying electromagnetic (EM) physics to guide us how to load positive-intrinsic-negative (PIN) diode as a tunable resistance to achieve variable absorption states. The designed PFMS absorber have been fabricated and experimentally verified on the flat and cylindrical foams, respectively. Good agreements can be found for both planar and cylindrical metasurface structures between full-wave simulations and measurements. Less than -10 dB reflectivity is achieved from 3.6 to 10.7 GHz (99%). The mimicry of time-varying scattering cross section (SCS) is further realized through real-time coding PFMS absorber, which can be precisely tuned from -30 dB to 0 dB with a step of 1.5 dB at 5.5 GHz and 10.4 GHz, respectively. © 2022, CC BY.

关键词： Polyvinyl chlorides

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