检索结果-南通市图书馆

Optimizing polyphase sequences for orthogonal netted radar systems

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2012年第4期23卷 529-535页

作者： Wenwu chen Zhengyu Cai rushan chen Zhao Zhao School of Electronic Engineering and Optoelectric Technology Nanjing University of Science and TechnologyNanjing 210094P.R.China

Orthogonal netted radar systems （ONRS） can fundamentally improve the radar performance by using a group of specially designed orthogonal polyphase code signals which require a very low aperiodic autocorrelation peak sidelobe level, low aperiodic cross-correlation, and a good resilience to small Doppler shifts. However, the existing numerical solutions degrade severely in the presence of small Doppler shifts. A new set of polyphase sequences is presented with good correlation properties as well as resilience to Doppler shifts. These sequences are built by using numerical optimization based on correlation properties as well as the Doppler effects on matched filter outputs, which maintains the Doppler tolerance. The statistical simulated annealing algorithm and the greedy code search method are used to optimize the sequences. Correlation and Doppler results are compared with the best-known sequences and show to be superior.

关键词： Doppler resilience netted radar orthogonal polyphasecode simulated annealing (SA).

Review on developments of novel specialty fibers： performance, application and process

在线全文

学校读者我要写书评

暂无评论

Frontiers of Optoelectronics 2014年第3期7卷 338-347页

作者： Qi MO cheng DU Wei chen Yili KE Tao ZHANG rushan chen Fiberhome Telecommunication Technologies Co. Ltd Wuhan 430074 China Accelink Technologies Co. Ltd Wuhan 430074 China

This paper reviews the development progress of optical fiber, the producing and application of the specialty optical fiber in the world. Finally it states the leading technology of optical fiber of the world. Specialty optical fibers are series of optical fiber which could satisfy special requirements. Recently, the rapidly growing need from fiber to the home （FTTH）, sensors, active optical link, energy conversion and delivery and fiber laser attracts researchers and optical companies to explore more possibilities of optical fiber and some novel specialty optical fibers were invented for the efforts. Bending insensitive optical fiber with the ability of extreme 3 mm bending diameter makes it possible to use the optical fiber as the electric wire in some extremely compact devices. Higher power was achieved in the fiber laser field with the development of rare earth doped fiber. Nanomaterials such as Au particles and ZnO nanostructures were utilized to extend the application in sensors and energy conversion. Pure silica design was commercialized to improve the radiation resistance of sensors based on fiber optics.

关键词： single mode optical fiber bending-insensitive rare earth doped fiber nano technology

Density-functional formula for strongly correlated systems

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2005年第5期15卷 395-401页

作者： WANG Huaiyu1*, HAN rushan2 and chen Nanxian1(1. Department of Physics, Tsinghua University, Beijing 100084, China 2. Department of Physics, Peking University, Beijing 100871, China) Department of Physics Tsinghua University Beijing 100084 China Department of Physics Peking University Beijing 100871 China

Density functional method is applied for strongly correlated systems. Based on the assumption that the systems are composed of electrons in singly-occupied orbitals and those in doubly-occupied orbitals, a set of self-consistent equations are obtained by standard variation procedure. The equations consist of two parts. One part is to solve the wave functions of the electrons in singly-occupied orbitals and the other is to solve the wave functions of the electrons in doubly-occupied orbitals. The physical meanings of the terms appearing in the equations are discussed.

关键词： density-functional theory strongly correlated systems doubly-occupied orbital two-particle wave function self-consistent equations.

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

一种旋转对称涂覆导体电磁散射高效分析方法

电波科学学报 2015年第6期30卷 1116-1122页

作者：樊振宏谭延君陈如山南京理工大学电子工程与光电技术学院南京210094

为改善传统方法分析旋转对称涂覆导体电磁散射问题的效率,提出了一种高效分析方法.该方法在介质表面建立电磁流混合场积分方程(Electric and Magnetic Current Combined Field Integral Equation,JMCFIE),在导体表面建立混合场积分方程(... 详细信息

为改善传统方法分析旋转对称涂覆导体电磁散射问题的效率,提出了一种高效分析方法.该方法在介质表面建立电磁流混合场积分方程(Electric and Magnetic Current Combined Field Integral Equation,JMCFIE),在导体表面建立混合场积分方程(Combined Field Integral Equation,CFIE),利用了旋转对称体在空间上的旋转周期性,只需要对表面的母线进行剖分,具有未知量少且阻抗矩阵条件数好的特点.根据等效原理与边界条件推导了JMCFIE-CFIE方程,并与传统的PMCHW-CFIE方法对比了求解效率.数值算例表明该方法能明显改善方程的收敛性.

关键词：电磁散射旋转对称体涂覆导体电磁流混合场积分方程

应用高阶有限元-局部共形完全匹配层算法分析电磁散射问题

在线全文

学校读者我要写书评

暂无评论

计算物理 2010年第2期27卷 263-268页

作者：朱剑甘辉樊振宏陈如山南京理工大学电子工程与光电技术学院江苏南京210094

提出局部共形完全匹配层在高阶有限元中的实现方法,用于分析三维电磁散射问题.基于定义在局部高阶单元上的实坐标、复坐标以及参数坐标三者之间的映射关系,局部共形完全匹配层不仅能够贴近复杂结构散射体的外廓形状设置截断区域,有效地... 详细信息

提出局部共形完全匹配层在高阶有限元中的实现方法,用于分析三维电磁散射问题.基于定义在局部高阶单元上的实坐标、复坐标以及参数坐标三者之间的映射关系,局部共形完全匹配层不仅能够贴近复杂结构散射体的外廓形状设置截断区域,有效地缩减有限元分析区域,而且由于保证了较高的几何拟合精度,可以有效地提高数值计算结果的准确性.利用这种结合局部共形完全匹配层的高阶有限元方法分析不同目标的电磁散射特性,数值结果表明方法的正确性和有效性.

关键词：局部共形完全匹配层有限元高阶曲单元高阶基函数

基于新型混合场积分方程的半空间三维均匀介质目标电磁散射分析

在线全文

学校读者我要写书评

暂无评论

计算物理 2010年第1期27卷 89-94页

作者：胡云琴安宁丁大志陈如山南京理工大学电子工程与光电技术学院江苏南京210094

利用介质半空间格林函数,将一种混合场积分方程(JMCFIE)推广应用到有耗半空间的均匀介质的散射分析中,以减少离散矩阵方程迭代求解时所需的迭代步数,提高矩量法(MoM)对半空间介质目标散射分析的求解效率.数值算例验证了方法的准确性和... 详细信息

利用介质半空间格林函数,将一种混合场积分方程(JMCFIE)推广应用到有耗半空间的均匀介质的散射分析中,以减少离散矩阵方程迭代求解时所需的迭代步数,提高矩量法(MoM)对半空间介质目标散射分析的求解效率.数值算例验证了方法的准确性和有效性.

关键词：有耗半空间均匀介质散射矩量法表面积分方程

A Stable Solution of Modified Time-domain Integral Equation for Antennas using MOD Method

在线全文

学校读者我要写书评

暂无评论

A Stable Solution of Modified Time-domain Integral Equation ...

2005'全国微波毫米波会议

作者： Rudan Jiang,Yifei Shi,Zhenbao Ye,rushan chen Department of Communication Engineering, Nanjing University of Science & Technology China,210094

＜正＞RWG basic functions is to be used in this paper with the marching-on-in degree（MOD） algorithm using Laguerre polynomials for analyzing radiation problem,which results in the accurate and stable transient responses.A central finite difference is used to approximate the time derivation instead of the complicated processing of derivative to cost much less time than general MOD *** numerical examples are preformed to demonstrate the accurateness and the stability of the proposed method.

关键词： Time domain Electric Field Integral Equation MOD Antennas Central Finite Difference.

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

介质散射的双线性高阶叠层基函数矩量法分析

电波科学学报 2016年第1期31卷 106-109,128页

作者：樊振宏何姿陈如山南京理工大学通信工程系南京210094

提出了一种基于双线性思想的高阶基函数降低矩量法分析介质目标电磁散射问题时的未知量.论文给出了双线性高阶叠层基函数的构造过程,并将其应用于介质的面积分方程分析中.数值算例比较了不同阶数时所需未知量以及计算精度,表明该高阶叠... 详细信息

提出了一种基于双线性思想的高阶基函数降低矩量法分析介质目标电磁散射问题时的未知量.论文给出了双线性高阶叠层基函数的构造过程,并将其应用于介质的面积分方程分析中.数值算例比较了不同阶数时所需未知量以及计算精度,表明该高阶叠层基函数在满足相同积分方程的计算精度时能比低阶基函数节省未知量.

关键词：电磁散射高阶基函数矩量法

在线全文

学校读者我要写书评

暂无评论

复杂媒质散射特性的FETI分析

计算物理 2010年第1期27卷 101-106页

作者：盛亦军朱剑樊振宏陈如山南京理工大学江苏南京210094

在分析复杂媒质的电磁场散射特性时,引入有限元撕裂对接法,对包含复杂媒质在内的整个计算空间做区域分解,通过合理的代数运算,将一个三维问题转化为二维问题进行求解,减小计算的复杂度.使用Krylov求解器,避免在形成交界面系统方程时,系... 详细信息

在分析复杂媒质的电磁场散射特性时,引入有限元撕裂对接法,对包含复杂媒质在内的整个计算空间做区域分解,通过合理的代数运算,将一个三维问题转化为二维问题进行求解,减小计算的复杂度.使用Krylov求解器,避免在形成交界面系统方程时,系数矩阵中的求逆运算.两个算例结果表明有限元撕裂对接法在分析复杂媒质散射特性时的正确性和有效性.

关键词：有限元撕裂对接法(FETI) 双各向同性媒质双各向异性媒质电磁散射