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Lead-free BiFeO_(3)-BaTiO_(3) based high-Tc ferroelectric ceramics:Antiferroelectric chemical modification leading to high energy storage performance

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Journal of Materiomics 2024年第4期10卷 819-827页

作者： Hongliang Wang Liang shu Liyu wei Xin Zhang Qian Li Jing-feng Li State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China

Dielectric capacitors have been widely used in pulsed power devices owing to their ultrahigh power density,fast charge/discharge speed,and excellent ***,developing lead-free dielectric materials with a combination of high recoverable energy storage density and efficiency remains a ***,a high energy storage density of 7.04 J/cm^(3) as well as a high efficiency of 80.5%is realized in the antiferroelectric Ag(Nb_(0.85)Ta_(0.15))O_(3)-modified BiFeO3-BaTiO3 ferroelectric *** achievement is mainly attributed to the combined effect of a high saturation polarization(Pmax),increased breakdown field(Eb),and reduction of the remnant polarization(Pr).The modification of pseudotetragonal BiFeO3 by Ag(Nb_(0.85)Ta_(0.15))O_(3) leads to a high Pmax,and the enhanced relaxor behavior gives rise to a small *** promoted microstructure(such as a dense structure,fine grains,and compact grain boundaries)after modification results in a high breakdown ***,both the recoverable energy density and efficiency exhibit high stability over a broad range of operating frequencies(1–50 Hz)and working temperatures(25–120℃).These results suggest that the(0.67–x)BiFeO_(3)-0.33BaTiO_(3)-xAg(Nb_(0.85)Ta_(0.15))O_(3) ceramics can be highly competitive as a lead-free relaxor for energy storage applications.

关键词： BiFeO_(3) Lead-free ceramics Dielectric capacitors Energy storage

B-spline surface fitting and simplified GO/PO analysis of subreflector correction for large Cassegrain antenna distortion compensation

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Research in Astronomy and Astrophysics 2018年第7期18卷 53-62页

作者： You Ban Cong-Si Wang shu-Fei feng wei Wang Bao-Yan Duan Key Laboratory of Electronic Equipment Structure Design Ministry of Education School of Electromechanical Engineering Xidian University

The main surface of a large Cassegrain antenna consists of a large number of panels. There are inevitably random and systematic errors which will degrade the antenna pattern and limit its applicability when working at high frequencies. Correcting the subreflector surface is difficult to describe by a global expansion effectively with a small amount of data. This paper presents a simple and clear way for correcting the subreflector surface of a large Cassegrain antenna for achieving such compensation. The advantage of the method is that the geometrical optics （GO） analysis is extremely simplified by the concept of equivalent prime-focus paraboloid, and corrected deformations of the subreflector surface are determined by simple formulas which represent the relationship between distortions of the subreflector surface and phase of the main surface current. The final shape of the subreflector surface is represented by a B-spline surface. To obtain a satisfactory antenna pattern with the simplest subreflector surface, the optimal number of B-spline patches are searched by particle swarm optimization （PSO）. The shaping process is verified by compensating a 22-m Cassegrain antenna whose main reflector has 96 panels. The results are satisfactory and demonstrate the simplicity and effectiveness of the approach.

关键词： telescopes reflector antennas subreflector shaping compensation

SET COVERING-BASED TOPSIS METHOD FOR SLOVING SUP-T EQUATION CONSTRAINED MULTI-OBJECTIVE OPTIMIZATION PROBLEMS

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Journal of Systems Science and Systems Engineering 2015年第3期24卷 258-275页

作者： Cheng-feng Hu shu-Cherng Fang Department of Applied Mathematics National Chaiyi University Edward P.Fitts Department of Industrial and Systems Engineering North Carolina State University

This paper considers solving a multi-objective optimization problem with sup-T equation constraints A set covering-based technique for order of preference by similarity to the ideal solution is proposed for solving such a problem. It is shown that a compromise solution of the sup-T equation constrained multi-objective optimization problem can be obtained by ＂solving an associated set covering problem. A surrogate heuristic is then applied to solve the resulting optimization problem. Numerical experiments on solving randomly generated multi-objective optimization problems with sup-T equation constraints are included. Our computational results confirm the efficiency of the proposed method and show its potential for solving large scale sup-T equation constrained multi-objective optimization problems.

关键词： Fuzzy relational equations fuzzy optimization set covering problems

Influence of adding carbon nanotubes and graphite to Ag-MoS_2 composites on the electrical sliding wear properties

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Acta Metallurgica Sinica(English Letters) 2010年第1期23卷 27-34页

作者： shu LI Yi feng Xiting YANG ~ v Department of Material Science and Engineering Hefei University of Technology Hefei 230009 China

Silver matrix composite brushes were fabricated by means of powder metallurgy, which included pressing at 300 MPa and then sintering for 1 h in pure H2 protective atmosphere at 700 ℃ and repressing at 500 MPa. Four kinds composites with different compositions were produced, and the mechanical properties and electrical wear performance were investigated. The results showed that the composite added with carbon nanotubes had a higher hardness and strength, a lower contact voltage drop and an excellent anti-wear property in electrical sliding wear, because of the reinforcement ability of carbon nanotubes. Adding graphite to the composite also decreased the wear loss and contact voltage drop, because graphite had an electrical current conducting ability which not only made the current pass the lubricating films easily but also eliminated and reduced the arc and spark effectively.

关键词： Ag-MoS2 composite Carbon nanotube Graphite Contact voltage drop Friction coefficient Wear loss

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火电机组热经济性通用分析模式的开发思路

热力透平 2004年第300期3卷 256-259页

作者：张树芳冯卫强郭江龙华北电力大学动力工程系河北保定071003

　通过对热经济性通用分析模式研究现状的分析,提出在矩阵算法下利用模块化的思想,把热力系统按照系统组成的最小部件类型划分模块,并在Delphi平台上把模块做成一个一个单一的组件。针对任意的热力系统,使用组件以堆积木的方式完成系统... 详细信息

　通过对热经济性通用分析模式研究现状的分析,提出在矩阵算法下利用模块化的思想,把热力系统按照系统组成的最小部件类型划分模块,并在Delphi平台上把模块做成一个一个单一的组件。针对任意的热力系统,使用组件以堆积木的方式完成系统的组态,实现组态同时自动生成平衡方程的一种新型的热经济性通用分析模式。

关键词：通用组件组态自动生成部件开发思路模块热经济性火电机组热力系统

Improved chirp scaling algorithm for parallel-track bistatic SAR

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Journal of Systems Engineering and Electronics 2009年第2期20卷 291-296页

作者： Li feng Li shu Zhao Yigong School of Electronics Engineering Xidian Univ. Xi'an 710071 P. R. China Dept. of Information Science and Electronic Engineering Zhejiang Univ. Hangzhou 310058 P. R. China EAAF Equipment Inst. of Land-based Air Defense Beijing 100085 P. R. China

The curvature factor of the parallel-track bistatic SAR is range dependent, even without variation of the effective velocity. Accounting for this new characteristic, a parallel-track chirp scaling algorithm （CSA） is derived, by introducing the method of removal of range walk （RRW） in the time domain. Using the RRW before the CSA, this method can reduce the varying range of the curvature factor, without increasing the computation load obviously. The azimuth dependence of the azimuth-FM rate, resulting from the RRW, is compensated by the nonlinear chirp scaling factor. Therefore, the algorithm is extended into stripmap imaging. The realization of the method is presented and is verified by the simulation results.

关键词： bistatic synthetic aperture radar chirp scaling range walk curvature factor parallel track

基于石墨烯电极TCNQ分子结热/电输运性质理论研究

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原子与分子物理学报 2025年第3期42卷 135-140页

作者：刘仪伟邱乙峰张蓓新疆大学物理科学与技术学院乌鲁木齐830046

本文采用密度泛函理论和非格林平衡函数,对基于石墨烯电极的7,7,8,8-四氰基苯醌二甲烷(Tetracyanoquinodimethane,TCNQ)分子结热/电输运性质进行系统研究.研究结果表明:随着中心TCNQ分子个数的增加,声子透射系数明显降低,即声子透射行... 详细信息

本文采用密度泛函理论和非格林平衡函数,对基于石墨烯电极的7,7,8,8-四氰基苯醌二甲烷(Tetracyanoquinodimethane,TCNQ)分子结热/电输运性质进行系统研究.研究结果表明:随着中心TCNQ分子个数的增加,声子透射系数明显降低,即声子透射行为受到极大抑制.与此同时,电子透射系数也有一定程度的减小.在热/电参数的协同作用下,伴随分子数量的增加分子结热电转换性能呈上升趋势,1TCNQ热电优值(ZT)为0.016,而2TCNQ则上升了1个数量级,ZT值达到0.11.最后,我们对分子结依赖于分子结构个数的自旋输运性质进行研究,发现TCNQ分子结具有显著的自旋过滤效应,其过滤能力随着TCNQ分子数量的增加而增加.该工作可为实验制备分子热电器件提供理论依据和数据支持.

关键词：锯齿状石墨烯纳米带 TCNQ分子自旋输运性质自旋过滤效应

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2-甲基丙烯酸(对-硼酸苄)酯的合成及聚合

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高分子通讯 1979年第4期 210-214页

作者：陆承勋李孝叔李唯富冯新德北京大学化学系

本文报导含硼的丙烯酸酯类单体2-甲基丙烯酸(对-硼酸苄)酯(V)的合成及聚合,2-甲基丙烯酸(对-硼酸苄)酯在乙醇中,以偶氮二异丁腈为游离基引发剂易于进行溶液聚合反应,聚合物的熔点为320—325℃(变色)。此外,(V)还能与甲基丙烯酸甲酯进行... 详细信息

本文报导含硼的丙烯酸酯类单体2-甲基丙烯酸(对-硼酸苄)酯(V)的合成及聚合,2-甲基丙烯酸(对-硼酸苄)酯在乙醇中,以偶氮二异丁腈为游离基引发剂易于进行溶液聚合反应,聚合物的熔点为320—325℃(变色)。此外,(V)还能与甲基丙烯酸甲酯进行铸板共聚合得到坚韧和透明的有机玻璃,实验表明,含硼的有机玻璃具有较好的耐热性,例如含(V)8％的甲基丙烯酸甲酯共聚体的软化温度可达158℃。

关键词：甲基丙烯酸马丁烯酸硼酸无机杀虫剂熔点熔解温度软化温度红外吸收光谱蒸馏水功能团

Proteomic Analysis of Rice Leaves Shows the Different Regulations to Osmotic Stress and Stress Signals

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Journal of Integrative Plant Biology 2010年第11期52卷 981-995页

作者： Lie-Bo shu wei Ding Jin-Hong Wu Fang-Jun feng Li-Jun Luo Han-wei Mei Huazhong Agricultural University Wuhan 430070China Shanghai Agrobiological Gene Center Shanghai 201106China

Following the idea of partial root-zone drying （PRD） in crop cultivation,the morphological and physiological responses to partial root osmotic stress （PROS） and whole root osmotic stress （WROS） were investigated in *** caused stress symptoms like leaf rolling and membrane *** stimulated stress signals,but did not cause severe leaf *** proteomic analysis,a total of 58 proteins showed differential expression after one or both treatments,and functional classification of these proteins suggests that stress signals regulate photosynthesis,carbohydrate and energy *** other proteins （anthranilate synthase and submergence-induced nickel-binding protein） were upregulated only in the PROS plants,indicating their important roles in stress ***,more enzymes were involved in stress defense,redox homeostasis,lignin and ethylene synthesis in WROS leaves,suggesting a more comprehensive regulatory mechanism induced by osmotic *** study provides new insights into the complex molecular networks within plant leaves involved in the adaptation to osmotic stress and stress signals.

关键词： PROTEOMICS CARRIER proteins SYMPTOMS METABOLISM MOLECULAR biology