电力传输通信网故障影响分析

讨论了故障影响分析的意义,举例说明电力传输通信网资源对象的故障状态,分析了电力传输通信网资源对象的单故障影响程度,并提出了多故障影响程度对比方法,从而实现对故障影响的分析。     

脉冲雷达中频采样系统的镜频抑制性能分析与参数设计

本文研究了脉冲雷达信号包络对中频采样的影响,重点分析了非理想包络对镜频抑制的影响,主要是产生镜频、幅度损失;作为一种特例,详细研究了简单脉冲信号矩形包络边沿对镜频抑制的影响;分析了不同系统参数对镜频抑制的影响,以保证脉冲边沿特性,并尽可能减少镜频影响.本文还分析了线性调频信号中频采样处理时的镜频抑制影响.     

工艺因素对厚膜电阻器性能的影响

本文主要介绍了厚膜混合集成电路中电阻器在生产过程中影响其性能的主要工艺因素。其中主要介绍了陶瓷基片对电阻器性能的影响,印制工艺对电阻器性能的影响,烧结工艺对电阻器性能的影响以及激光调阻工艺对电阻器性能的影响。     

谐振腔镜对激光模式匹配效果的影响

利用匹配透镜将激光光束与谐振腔进行匹配时，均不考虑谐振腔镜对匹配效果的影响。本文从理论上分析了进行激光模式匹配时谐振腔镜对匹配效果的影响，计算了影响的程度，并给出了消除影响的修正公式。     

后向散射对激光水下成像的影响研究

为研究后向散射对水下成像的影响,采用辐射传输理论建立了激光水下成像后向散射理论模型,提出了表征后向散射对目标识别影响程度的水下成像后向散射影响系数,给出了距离选通成像后向散射功率及后向散射影响系数的解析表达式。利用Matlab进行了数值模拟分析,得出了水下成像后向散射随探测水深及水衰减系数的变化规律,证明了考虑后向散射对成像质量的影响时,水衰减系数远大于探测水深的影响,说明了非对称因子的取值对成像质量具有较大的影响。     

GPS电子干扰范围及效果分析

介绍了GPS导航系统的基本原理及其干扰和反干扰措施。以INS/GPS组合导航为例,研究了干扰距离对其干扰效果的影响。分析了影响干扰距离的因素并研究了各因素对干扰距离影响的大小,指出有效干扰范围不仅受干扰功率的影响,还受到干扰机和接收机天线方向增益的影响及地表曲率决定的视在距离的限制。讨论了如何对未来具有强抗干扰能力GPS接收机进行有效干扰的干扰机配置方案。     

制冷型红外探测器组件降温时间的影响因素

以工作物质的一定压力、温度为基准状态,定义了组件热容量影响系数、工质状态(压力/温度)影响系数、流量影响系数等参数,为红外探测器组件的降温时间计算建立理论模型,用该模型计算分析了高温环境下组件的热容量和工质制冷量的变化对降温时间的影响,并和实验结果进行了比较.另外分析了实际情况小幅偏离基准状态对实验结果的影响.     

社交网络环境下影响最大化的问题分析

社交网络具有社区特征,很大程度上影响了信息在网络中的传播,构建了一些计算节点影响的参数,给出了社区结构影响最大化的计算模型,借助试验模型,以验证方式分析了模型。最终利用计算模型,经过设计与计算,得到了基于影响最大化的舆论牵引策略算法,于社区舆论引导系统中获得了比较不错的引导效果。     

电压电流相序对电能测量影响的研究

阐述了加强电压相序对电能测量影响研究的重大意义,分析了电源相序接入错误对计量的影响,并对常见电能表错误接线进行了分析,提出了减少电压相序对电能测量影响的解决对策。     

电气设备红外诊断相对温差判别法影响因素分析

根据红外辐射理论和红外热像仪的测温原理,推导了相对温差影响因素的计算公式;分析了环境温度、物体表面发射率和红外热像仪工作波段对相对温差的影响,得出了环境温度对相对温差影响较小,设备表面发射率对相对温差有一定影响,在相同条件下,使用长波热像仪测温对相对温差影响较小的结论.     

Comparison of the dispersion properties of higher order FDTD schemes and equivalent-sized MRTD schemes

The dispersion errors of higher order finite-difference time-domain (HO-FDTD) algorithms are compared to those of multiresolution time-domain (MRTD) algorithms that have equivalent spatial stencil sizes. Both scaling-function-based MRTD (S-MRTD) and wavelet-function-based MRTD (W-MRTD) schemes are considered. In particular, the MRTD schemes considered include the Coifman scaling functions and the Cohen-Daubechies-Feauveau (CDF) biorthogonal scaling and wavelet functions. In general, the HO-FDTD schemes are more accurate than their MRTD counterparts.     

一种便携式外场用MRTD测试仪的研制

目前热像仪MRTD测试主要在室内,为了满足外场热像仪MRTD测试的需求,研制了一种便携式MRTD测试仪.文章主要阐述了仪器的研制原理、光学优化设计、结构设计及黑体组件等的设计要点.目前,该仪器已经用于外场环境的热像仪MRTD测试,结果准确.     

探测条件对红外热成像系统MRTD影响的研究

在考虑目标的尺寸、探测等级、探测概率及大气环境等因素情况下,研究了热成像系统的最小可分辨温差（MRTD）,建立了一个改进的MRTD模型。由于大气透过率与波长和距离相关,利用光谱等分法计算大气透过率,将探测波长范围等分为一个个窄波段,利用MODTRAN软件计算在一定大气条件和距离下每个窄波段的大气透过率。通过调用对应波长的透过率,计算了探测波长范围内热成像系统的MRTD,提高了MRTD的准确性和适用性。     

动态红外成像系统MRTD的测试与分析

提出一种在正弦运动状态下测试红外热像仪最小可分辨温差(MRTD)的方法,建立了正弦运动状态下测试靶标灰度对比度变化的数学模型,采用MATLAB软件模拟得到该数学模型曲线,从理论上直观地阐述了在正弦运动下,目标四杆靶灰度对比度的变化趋势,为MRTD的动态测试提供了坚实的理论基础。论文设计并研制了实验平台,采用统计学方法对实验数据进行分析,得到扰动情况下红外热像仪的MRTD值。实验结果表明,提出的方法和实验装置能准确地完成动态MRTD的测试。     

采样红外成像系统仿真及最小可分辨温差预测方法研究

提出一种基于采样红外成像系统仿真图像的最小可分辨温差MTRD预测方法。该方法从红外成像系统信号传递方程出发,模拟生成不同空间频率、辐射温度的标准四周期矩形样条;利用调制传递函数法和象素处理法,仿真了系统各组成模块的几何扭曲、模糊效应、噪声特性和非线性效应;由多名观察者观察样条仿真图像,统计正确判断概率。实现了MRTD的预测．仿真结果表明：该方法预测的MRTD值能够与实际测量的MRTD值有很好的一致性。     

焦平面热成像系统离散采样性能评价方法

在充分研究焦平面热成像系统欠采样成因的基础上,分析了ANN法和基于信息理论的光电成像系统欠采样混频评价方法,把欠采样混频看作是系统的噪声,并和其他系统噪声一起加到MRTD模型中,给出了包含欠采样噪声的MRTD模型。对比含欠采样噪声的MRTD模型仿真数据与文献中实测MRTD数据,该模型对MRTD仿真结果与测量数据走势基本一致,能够用于评价欠采样混频对热成像系统性能的影响,但模型的精确性还需要进一步修正。下一步将通过测量各种型号焦平面热像仪的MRTD,对含欠采样混频的MRTD模型进行修正。     

Multiresolution time-domain algorithm using CDF biorthogonalwavelets

A new approach to the multiresolution time-domain (MRTD) algorithm is presented in this paper by introducing a field expansion in terms of biorthogonal scaling and wavelet functions. Particular focus is placed on the Cohen-Daubechies-Feauveau (CDF) biorthogonal-wavelet class, although the methodology is appropriate for general biorthogonal wavelets. The computational efficiency and numerical dispersion of the MRTD algorithm are addressed, considering several CDF biorthogonal wavelets, as well as other wavelet families. The advantages of the biorthogonal MRTD method are presented, with emphasis on numerical issues     

MRTD: new time-domain schemes based on multiresolution analysis

The application of multiresolution analysis to Maxwell's equations results in new multiresolution time-domain (MRTD) schemes with unparalleled inherent properties. In particular, the approach allows the development of MRTD schemes which are based on scaling functions only or on a combination of scaling functions and wavelets leading to a variable mesh grading. The dispersion of the MRTD schemes compared to the conventional Yee finite-difference time-domain (FDTD) scheme shows an excellent capability to approximate the exact solution with negligible error for sampling rates approaching the Nyquist limit. Simple microwave structures including dielectric materials are analyzed in order to illustrate the application of the MRTD schemes and to demonstrate the advantages over Yee's FDTD scheme with respect to memory requirements and execution time     

Application of Haar-wavelet-based multiresolution time-domainschemes to electromagnetic scattering problems

The multiresolution time-domain (MRTD) algorithm is applied to the problem of general two-dimensional electromagnetic scattering. A Haar wavelet expansion is utilized. A parallel between Haar MRTD and the classic Yee finite-difference time-domain (FDTD) algorithm is discussed, and results of simulations on canonical targets are shown for comparison. We focus on the incident-field implementation, which, in our case, consists of a pulsed plane wave. Also, we consider scattering in a half-space environment, with application to subsurface sensing. The results illustrate the advantage of the Haar MRTD method as compared with the classic FDTD, which consists of reduced memory and execution time requirements, without sacrificing accuracy     

Application of an anisotropic perfectly matched layer absorber for open boundary truncation in the multiresolution time domain scheme

We apply an anisotropic perfectly matched layer (APML) absorber for open boundary truncation in implementation of the multiresolution time domain (MRTD) scheme. We develop an APML update algorithm to handle a general APML region in the MRTD formulations with the content of the leapfrog algorithm applied in the conventional finite-difference time-domain method. We also discuss the boundary truncations for both perfectly electric conductor (PEC) and perfectly magnetic conductor (PMC) walls using the image techniques. We validate the algorithm by analyzing various guided wave and antenna structures. It is found that the APML performs well for absorbing electromagnetic waves in the MRTD algorithm.