检索结果-南通市图书馆

Optimizing the grain size and grain boundary morphology of (K,Na) NbO_(3)-based ceramics: Paving the way for ultrahigh energy storage capacitors

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materiomics 2021年第4期7卷 780-789页

作者： Xiaozhi Wang Yu Huan Peiyao Zhao Xiaoming Liu Tao Wei qiwen zhang Xiaohui Wang School of Material Science and Engineering University of JinanJinan250022China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education) Northeastern UniversityShenyang110819China The Chinese Ceramic Society Beijing100831China

Relaxor dielectric ceramic capacitors are very attractive for high-power energy ***,the low breakdown strength severely restricts improvements to the energy storage density and practical ***,a strategy of designing small grain sizes and abundant amorphous grain boundaries is proposed to improve the energy storage properties under the guidance of phase field theory.0.925(K_(0.5)Na_(0.5))NbO_(3)-e0.075Bi(Zn_(2/3)(Ta_(0.5)Nb_(0.5))1/3)O_(3)(KNNe-BZTN)relaxor ferroelectric ceramic is taken as an example to verify our *** grain sizes and grain boundaries of the KNNeBZTN ceramics are carefully controlled by the high-energy ball milling method and twoestep sintering *** analysis and diffusion reflectance spectra demonstrate that KNNeBZTN ceramics with a small grain size and abundant amorphous grain boundary exhibit a lower charge carrier concentration and higher band *** a consequence,the breakdown electric field of KNNeBZTN ceramics increases from 222 kV/cm to 317 kV/cm when the grain size is decreased from 410 nm to 200 nm,accompanied by a slightly degraded maximum *** ceramics with an average grain size of~250 nm and abundant amorphous grain boundaries exhibit optimum energy storage properties with a high recoverable energy density of 4.02 J/cm^(3) and a high energy efficiency of 87.4%.This successful local structural design opens up a new paradigm to improve the energy storage performance of other dielectric ceramic capacitors for electrical energy storage.

关键词： Grain size Grain boundary KNN-based dielectric ceramic capacitors Energy storage properties Breakdown strength Two-step sintering strategy

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

FSO-WOFDM系统的实验研究

红外与激光工程 2018年第10期47卷 240-246页

作者：柯熙政张棋雯西安理工大学自动化与信息工程学院陕西西安710048

在无线光正交频分复用(FSO-OFDM)系统中,因需要加入循环前缀而消耗近20%的带宽,降低了数据传输效率。为了进一步减少带宽损耗,改善系统性能,采用小波包变换代替FSO-OFDM中的傅里叶变换,设计了一种基于小波变换的无线光正交频分复用(FSO-... 详细信息

在无线光正交频分复用(FSO-OFDM)系统中,因需要加入循环前缀而消耗近20%的带宽,降低了数据传输效率。为了进一步减少带宽损耗,改善系统性能,采用小波包变换代替FSO-OFDM中的傅里叶变换,设计了一种基于小波变换的无线光正交频分复用(FSO-WOFDM)系统。该系统无需加入循环前缀,利用小波基函数的正交性来抑制子载波间的干扰。根据FSO-WOFDM系统原理,研究了信道估计方法、湍流强度、小波基对FSO-WOFDM系统误码率的影响,对比分析了FSO-WOFDM与FSO-OFDM的系统性能,并通过实验验证了FSO-WOFDM系统的可行性及其优良的抗混合噪声干扰能力。

关键词：无线光通信离散小波包变换正交频分复用 Mallat算法

Absorption and Accumulation of Heavy Metal from Soil by Leaves of Populus x euramericana cv.‘Neva’Plantation

在线全文

学校读者我要写书评

暂无评论

Chinese Forestry Science and Technology 2012年第3期11卷 51-52页

作者： Li Jinhua He Yan Duan Jianping zhang qiwen Key Laboratory of Tree Genetics and Breeding of State Forestry Administration Research Institute of ForestryChinese Academy of Forestry Beijing Management Bureau of Forest Seed and Seedling Yanqing Management Bureau of Forest Seed and Seedling

The absorption and enrichment of heavy metal elements by leaves of Populus×euramericana cv.’Neva’ were analyzed through content assessing of heavy metal elements in soils of three forest lands at Fangshan District in the southern suburb of Beijing. These forest lands with P.×euramericana cv. ’Neva’plantation were around with the various sources of pollution such as cement mill,stone mill, sewage and *** of heavy metal elements such as Cd,Pb,Cu,and Zn were found in the soil samples and leaves of P.×euramericana cv.’Neva’ grown on the three forest lands which were *** results of investigation showed that the soils of three forest lands were polluted with Pb, Cd,Cu and Zn in varying *** contents of Pb,Cu and Zn in soils were significantly different among the three forest lands,whereas the average content of Cd(0.077 6 mg·kg-1) was less but that of Pb,Cu,and Zn(37.61,26.25 and 90.3 mg·kg-1 ) were more than the average background value of *** contents of Pb,Cd,Cu and Zn in leaves of P.×euramericana cv.’Neva’ were different among three *** the changes of heavy metal contents in soil samples,there was no regularity on the changes of different heavy metal contents in leaves of P.×euramericana cv.’Neva’ grown on different forest land.P.×euramericana cv.’Neva’ can absorb and accumulate Pb,Cd,Cu and Zn in soil but showed different capacities of absorption and accumulation with the order of Cd>Zn>Cu>***,its absorption and accumulation capacity for Cd was strong with maximum enrichment factor higher than 16 and showed high accumulation on low background,whereas its enrichment capacities for Pb and Cu were relatively poorer with average enrichment factor of less than *** different forest lands,there existed great difference on absorption capacity of P.×euramericana cv.’Neva’ with the same heavy metal.

关键词： Populus×euramericana cv.'Neva’ soil leaves heavy metal absorption enrichment

在线全文

学校读者我要写书评

暂无评论

基于教学优化算法求解置换流水车间调度问题

系统仿真学报 2022年第5期34卷 1054-1063页

作者：张其文张斌兰州理工大学计算机与通信学院甘肃兰州730050

针对置换流水车间调度问题,将连续算法与离散策略相结合,提出一种多班级教学优化算法。采用基于置换变异改进的NEH(nawaz enscore ham)种群初始化方法,兼顾初始解的质量和多样性。在教学阶段,引入离散的自适应教学,并给出去重的操作,避... 详细信息

针对置换流水车间调度问题,将连续算法与离散策略相结合,提出一种多班级教学优化算法。采用基于置换变异改进的NEH(nawaz enscore ham)种群初始化方法,兼顾初始解的质量和多样性。在教学阶段,引入离散的自适应教学,并给出去重的操作,避免了无意义的教学过程。新增了基于莱维飞行的自学策略,同时以变邻域搜索的方式模拟离散阶段的自学。将相互学习与班级交流合并,在保证优秀个体交流的基础上,提高学习的效率。通过对标准测试集Rec进行测试,并与其他算法比较,验证了算法的有效性和稳定性。

关键词：置换流水车间调度多班级教学优化算法去重操作自学策略优势个体交流

Modulation of the octahedral structure and potential superconductivity of La3Ni2O7 through strain engineering

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2025年第3期Mechanics & Astronomy) .卷 149-156页

作者： Zihao Huo Zhihui Luo Peng zhang Aiqin Yang Zhengtao Liu Xiangru Tao Zihan zhang Shumin Guo qiwen Jiang Wenxuan Chen Dao-Xin Yao Defang Duan Tian Cui Key Laboratory of Material Simulation Methods & Software of Ministry of Education State Key Laboratory of Superhard Materials College of Physics Jilin University Center for Neutron Science and Technology Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices State Key Laboratory of Optoelectronic Materials and Technologies School of Physics Sun Yat-sen University MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter Shaanxi Province Key Laboratory of Advanced Functional Materials and Mesoscopic Physics School of Physics Xi'an Jiaotong University Institute of High Pressure Physics School of Physical Science and Technology Ningbo University

The recent transport measurements of La3Ni2O7uncovered a “right-triangle” shape of the superconducting dome in the pressure-temperature（P-T） phase diagram. Motivated by this, we perform theoretical first-principles studies of La3Ni2O7with the pressure ranging from 0 to 100 GPa. Notably, we reveal a pressure dependence of the Ni-dz2electron density at the Fermi energy(nzEF) that highly coincides with such shape. On this basis, we further explore the electronic structure under uniaxial stress. By tracking the stress response of nzEF, we propose that superconductivity can be achieved by applying only ～2 GPa of compression along the c axis. The idea is further exemplified from the perspectives of lattice distortion, band structure, Fermi surface and superconducting phase coherence. We also discuss the possible charge modulation under the stress and provide an insight into the relation between nz E Fand the superconducting Tcin La3Ni2O7system. Our study provides new routes to the search of high-Tcsuperconductors in future experiments.

关键词： nickelate superconductors density functional theory strong correlated systems strain engineering

同方期刊数据库

Non-coding RNAs in acute ischemic stroke:from brain to periphery

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第1期20卷 116-129页

作者： Shuo Li Zhaohan Xu Shiyao zhang Huiling Sun Xiaodan Qin Lin Zhu Teng Jiang Junshan Zhou Fuling Yan qiwen Deng Department of Neurology Nanjing First HospitalNanjing Medical UniversityNanjingJiangsu ProvinceChina Department of Neurology Zhongda HospitalSchool of MedicineSoutheast UniversityNanjingJiangsu ProvinceChina General Clinical Research Center Nanjing First HospitalNanjing Medical UniversityNanjingJiangsu ProvinceChina

Acute ischemic stroke is a clinical emergency and a condition with high morbidity,mortality,and *** predictive,diagnostic,and prognostic biomarkers and effective therapeutic targets for acute ischemic stroke remain *** innovations in high-throughput gene sequencing analysis,many aberrantly expressed non-coding RNAs(ncRNAs)in the brain and peripheral blood after acute ischemic stroke have been found in clinical samples and experimental *** expressed ncRNAs in the post-stroke brain were demonstrated to play vital roles in pathological processes,leading to neuroprotection or deterioration,thus ncRNAs can serve as therapeutic targets in acute ischemic ***,distinctly expressed ncRNAs in the peripheral blood can be used as biomarkers for acute ischemic stroke prediction,diagnosis,and *** particular,ncRNAs in peripheral immune cells were recently shown to be involved in the peripheral and brain immune response after acute ischemic *** this review,we consolidate the latest progress of research into the roles of ncRNAs(microRNAs,long ncRNAs,and circular RNAs)in the pathological processes of acute ischemic stroke–induced brain damage,as well as the potential of these ncRNAs to act as biomarkers for acute ischemic stroke prediction,diagnosis,and *** from this review will provide novel ideas for the clinical application of ncRNAs in acute ischemic stroke.

关键词： acute ischemic stroke apoptosis blood–brain barrier damage circular RNAs excitatory toxicity long non-coding RNAs microRNAs neuroinflammation non-coding RNAs oxidative stress

Optimal Trajectory Planning Algorithm for VSCMG Based on Mode Scheduling

在线全文

学校读者我要写书评

暂无评论

Optimal Trajectory Planning Algorithm for VSCMG Based on Mod...

GNSS Interference Suppression for Spacecraft Using Integrated Navigation based on Support Vector Regression

第40届中国控制会议

作者： Zhaoyang Cheng zhanghai Nie Chao Zhong He Zhu qiwen zhang Shanghai Institute of Spaceflight Control Technology Shanghai Key Laboratory of Aerospace Intelligent Control Technology

An optimal trajectory planning algorithm for Variable Speed Control Moment Gyroscope（VSCMG） based on mode scheduling is proposed, aiming at the application of large angle attitude maneuver of agile spacecraft. Based on the torque generating characteristic of the VSCMG and the mission requirement of spacecraft, Gauss pseudospectral method is used to plan the optimal trajectory of the spacecraft’s attitude maneuver task. In the process of large angle attitude maneuver, the wheel speed of VSCMGs system maintains a constant speed, and the system switches to CMG mode（similar to the SGCMGs system）;In the attitude stability phase, the gimbal of the VSCMGs system is locked, and the system switches to RWs mode（Similar to the RWs system of the pyramid configuration）, which generates fine control torque to overcome disturbance torque. The simulation results show the effectiveness and practicability of the optimal trajectory planning algorithm.

关键词： Variable Speed Control Moment Gyroscope(VSCMG) Gauss pseudospectral method Singularity Trajectory planning

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

GNSS Interference Suppression for Spacecraft Using Integrate...

第43届中国控制会议

作者： Fan Yang qiwen zhang Hao Yu Xiang Guo Cheng Gong Shanghai Aerospace Control Technology Institute

Global Navigation Satellite System(GNSS) determines the Orbit information of spacecraft,while the signal is easily affected by interference in *** GNSS interference suppression methods based on GNSS/Inertial Navigation System(INS) integrated navigation do not make confidence assessment for the error correction values of position and *** this study,a method is proposed to assess interference by analyzing the features of geocentric distance,velocity,acceleration,semi-major axis,eccentricity ratio and orbit inclination using Support Vector Regression(SVR).Then,the impact of different kernel functions is analyzed and the Mean-Square Error(MSE) of the fine Gaussian radial basis kernel reaches *** position and velocity accuracy of the optimized method improves approximately 28.5% and 27.7% *** paper provides technical support for the research and implementation of GNSS interference suppression technology,which is of great significance to maintain the normal operation of spacecraft.

关键词： global navigation satellite system interference suppression support vector regression GNSS/INS integrated navigation

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

独立自适应调整参数的粒子群优化算法

计算机科学与探索 2020年第4期14卷 637-648页

作者：张其文尉雅晨兰州理工大学计算机与通信学院兰州730050

针对传统粒子群优化算法在求解复杂优化问题时易陷入局部最优和依赖参数的取值等问题,提出了一种独立自适应参数调整的粒子群优化算法。算法重新定义了粒子进化能力、种群进化能力以及进化率,在此基础上给出了粒子群惯性权重及学习因子... 详细信息

针对传统粒子群优化算法在求解复杂优化问题时易陷入局部最优和依赖参数的取值等问题,提出了一种独立自适应参数调整的粒子群优化算法。算法重新定义了粒子进化能力、种群进化能力以及进化率,在此基础上给出了粒子群惯性权重及学习因子的独立调整策略,更好地平衡了算法局部搜索与全局搜索的能力。为保持种群多样性,提高粒子向全局最优位置的收敛速度,在算法迭代过程中,采用粒子重构策略使种群中进化能力较弱的粒子向进化能力较强的粒子进行学习,重新构造生成新粒子。最后通过CEC2013中的10个基准测试函数与4种改进粒子群算法在不同维度下进行测试对比,实验结果验证了该算法在求解复杂函数时具有高效性,通过收敛性分析说明了算法的有效性。

关键词：粒子群算法(PSO) 惯性权重学习因子粒子重构