电力系统状态估计研究综述

电力系统状态估计是能量管理系统(EMS)的重要组成部分,其结果直接影响电网调度的智能化分析与决策。综述了电力系统状态估计的研究现状。首先,简要分析了电力系统经典静态状态估计和动态状态估计的基本功能及其发展;然后,介绍了几种目前新出现的状态估计方法,即新息图状态估计、谐波状态估计、配电网状态估计等,指出各个方法的优缺点。最后,对状态估计方法中值得研究的方面进行了展望。     

岸基水听器阵列阵形估计方法研究

阐述了基于时延估计的阵形估计方法的基本原理,该方法比基于传感器测量和基于匹配场处理的方法具有更强的适应性和较高的精度.对比分析了单辅助信源和双辅助信源的相应的阵形估计方法,其中单信源方法用装配间距近似各个阵元间的实际间距.对已有海试数据阵形估计处理的结果表明,阵列弯曲不大时,单源方法可以得到与双源方法相当精度的估计结果,用估计阵形进行空间谱分析,进一步说明了结果的有效性.基于时延估计的阵形估计方法对长水听器阵列的应用及阵形估计具有较大应用价值.     

盲源分离用于DOA估计研究

方位估计是水下目标定位、跟踪的前提。提出了一种复数域奇异值分解盲源分离方法,估计出了阵列流形,并利用阵列流形表现出的相位关系完成了目标方位估计。通过仿真实验与MUSIC高分辨方位估计方法和相关文献的方法进行了对比,结果表明该方法能很好地实现目标方位的实时估计,且性能更佳。     

用多项式模型和自适应滤波估计瞬时频率

本文论述了非平稳信号瞬时频率(IF)的估计方法,包括基干最小均方误差(LMS)算法或递推最小二乘(RLS)算法的自适应IF估计方法和基于信号相位多项式模型的IF估计方法。对各种估计方法的估计方差与理论方差下限进行了比较。说明了,基于互Wigner分布的估计方法所需信噪比(SNR)门限值最低。在低SNR、短信号记录的情况下,用多项式相位模型与最大似然法可以获得比较可靠的IF估计。     

几种基于FFT的频率估计方法精度分析

介绍了噪声背景中正弦信号频率估计的方差下限，对利用FFT主瓣内两条幅度最大谱线进行插值的频率估计方法（Rife-Jane方法和Quinn方法）以及利用FFT相位进行频率插值的方法（分段FFT相位差法和重叠FFT相位差法）的方差进行了理论分析，推导了Quinn方法的频率估计方差计算公式．提出了通过滤波进一步提高分段FFT相位差法的频率估计精度的方法。通过计算机MonteCarlo模拟实验对上述各种方法的频率估计精度以及加窗函数的影响进行了分析并与理论下限进行了比较，指出了每种方法所能达到的估计精度。     

自回归模型参数的经验Bayes估计

用核估计的方法，构造了自回归模型ＡＲ（ｐ）的参数的一种经验Ｂａｙｅｓ（ＥＢ）估计，证明了这种估计的渐近最优性。模拟计算表明，该估计不仅优于古典估计方法，也优于现有的ＥＢ估计方法     

数字采样测量噪声误差的估计和分析

针对高频数字采样中的附加噪声和时间抖动误差估计问题，给出了高频数字采样测量噪声误差的最大似然估计方法。在获得了相应的数学模型后，对最小二乘估计和最大似然估计方法进行了比较。仿真结果表明，对于此类误差最大似然估计比最小二乘估计有效性更好。另外最大似然估计的一个优点是用于不确定度计算的克拉美一罗下限值更易于获得。     

基于逆系统分析法的多输入-多输出系统动态载荷的优化估计

本文提出了一种多输入－多输出系统动态的优化估计方法。该方法可以使估计的总体均方误差最小。首先,采用逆系统分析方法建立误差估计方程;其次,利用非因果维纳滤波理论导出了动态载荷的优化估计器。数字仿真结果表明,该方法在抑制测量噪声对估计精度的影响方面具有良好的效果。与传统方法估计结果的对比分析表明,所提出的方法更为有效和实用。     

基于时延估计的海底线阵阵形估计方法研究

阵形估计是水听器阵列应用中的关键问题,基于时延估计的阵形估计方法比基于传感器测量和基于匹配场处理的方法具有更强的适应性和较高的精度。针对浅海水听器阵列中水平长线阵存在的纵向相关振荡现象引起的不能简单以某一阵元为基准求相对时延的问题,充分利用了阵元信号的高相关性,提出了基于子阵时延的阵形估计方法,针对子阵间时延估计误差向阵端累积的问题,该方法以时延估计的克拉美罗界为依据提出了合理的子阵方式,在一定程度上减小了误差传递。对已有海试数据阵形估计处理的结果表明,相对于单源固定间距方法和未分子阵的双源时延估计方法,基于子阵时延的阵形估计方法满足阵元间距的约束,有较好的空间谱特性,减小了阵形估计误差,对长水听器阵列的应用及阵形估计具有较大应用价值。     

时延估计方法的分析

对周内外时延估计的最新研究现状及各种算法进行研究,在研究了大量时延估计文献的基础上,分析了广义相关法、广义相位谱法、自适应算法及其改进算法,分析了各种算法之间的关系以及各自的特点。重点论述了现代信号处理算法与时延估计算法相结合的各种时延估计方法及其在非平稳信号中的应用,同时,分析了带宽对时延估计精度的影响及宽带信号的时延估计方法,指出了时延估计算法还需要进一步研究的方向。     

基于θ方法的波形松弛方法的A稳定

描述芯片或电力系统运行规律的常用数学模型是高维微分代数方程组，其中的微分方程组太大，线性多步法和Runge-Kutta法等经典数值方法均不能有效求解。为求解这些微分方程组，借鉴常微分方程经典数值方法的A稳定定义，提出了波形松弛方法A稳定(强A稳定)，给出了基于θ方法的波形松弛方法 A稳定(强A稳定)和非A稳定的条件，以及几个支持理论结果的数值算例。研究结果表明WR方法并非天然继承底层方法的A稳定性，为使波形松弛方法 A稳定，需要使用A稳定的底层方法和适当的分裂函数，这为刚性方程WR方法的构造奠定了理论基础。此外，借鉴经典数值方法的B稳定定义，提出了波形松弛方法的B稳定(强B稳定)，给出了波形松弛方法强B稳定的条件。     

A study of the use of concept selection methods from inside a company

Design methods have been studied by researchers for decades. Academia considers their impact on industry to be insufficient. The objective of this research is to understand the use and impact of design methods in the context of a specific company, Volvo Car Corporation (VCC), by describing the behaviour of engineers in relation to methods, to assist in the future development of design methods and tools. We mainly concentrate on concept selection methods because of their relevance in this company. The data presented is the result of qualitative research carried out during 4 years at VCC, where the authors were located as researchers. The research shows that many methods are employed besides those with an academic name, that some in-company methods used contain improvements to methods researched by academia, that some modifications to academic methods lead to unreliable results, and that there is a lack of objectivity in method modification. For these reasons, the authors suggest further research on understanding the principles of successful and unreliable modification of concept selection methods.     

Nonparametric variance-based methods of assessing uncertainty importance

This paper examines the feasibility and value of using nonparametric variance-based methods to supplement parametric regression methods for uncertainty analysis of computer models. It shows from theoretical considerations how the usual linear regression methods are a particular case within the general framework of variance-based methods. Examples of strengths and weaknesses of the methods are demonstrated analytically and numerically in an example. The paper shows that relaxation of linearity assumptions in nonparametric variance-based methods comes at the cost of additional computer runs.     

A family of methods with three-term recursion formulae

A state-of-the-art survey of a family of vector iterative methods with three-term recursion formulae is presented. The methods can be classified under two broad categories. The Chebyshev semi-iterative type of methods and the conjugate gradient type of methods. Relationships between the iteration parameters of the methods are established and computational techniques for estimating these parameters are presented. Numerical tests confirm the superiority of the conjugate gradient method for linear problems and the Chebyshev semi-iterative methods for nonlinear problems.     

航空摄影胶片冲洗质量控制系统的研究与实现

本文介绍了一套实用的摄影冲洗质量控制系统。在简要介绍系统建立的基本思想、主要技术原理和软硬件组成的基础上,重点阐述了系统研究并解决的主要问题—影像密度数据采集、胶片感光特性参数解算、冲洗工艺确定和影像质量评价。实际应用表明,系统确定的最佳冲洗工艺和影像质量评价结果准确、方法实用,能有效提高航空航天摄影冲洗质量,有着很好的推广应用前景。     

Experimental comparison of fourier transformation and model-fitting methods of spectral analysis

A summary of the results of an extensive comparative experimental study of Fourier transformation and model-fitting methods of spectral analysis of random time-series data is presented. It is illustrated that Fourier transformation methods can be an essential companion to model-fitting methods even for short data segments with underlying sharp spectral peaks. The best spectrum estimates can be obtained by taking advantage of the strengths of both types of methods. For example, it is shown that detection and estimation of the frequencies of spectral lines for short data segments can be best accomplished using certain parametric methods in conjunction with Fourier transformation methods to aid in model-order selection and identification of spurious peaks in the parametric spectrum estimate, and that estimation of amplitude and phase for sine-wave removal, given frequency estimates, and spectrum estimation after sine-wave removal can often be best accomplished with Fourier transformation methods alone.     

Fatigue of metals under nonuniform stressed state. part 2. methods of the analysis of research results

We review the currently available methods that are used to explain the difference in fatigue strength of metals and alloys under conditions of uniform and nonuniform stressed states. We discuss (i) the empirical methods, (ii) the methods allowing for the difference between nominal and effective cyclic stresses, (iii) the methods based on the notions of statistical theories of strength, and (iv) the methods assuming that responsible for fatigue failure are the averaged stresses in the surface layer. The calculated results are verified against experimental findings.     

Postintegration methods for numerical integration of non-linear dynamic equations of motion

The paper presents a family of methods with postintegration, for numerical integration of non-linear dynamic equations of motion of discrete systems. Both explicit and implicit algorithms of these methods are conditionally stable, but can give solutions of accuracy of a few orders higher than the known methods with preintegration, corresponding to them. A general analysis of stability and accuracy of single-step methods is carried out. The postintegration methods have been tested on a single-degree-of-freedom non-linear system.     

频域传递路径分析方法（TPA）的研究进展

传递路径分析方法(Transfer Path analysis,TPA)是当前诊断机械系统振动和噪声最通用的手段。本文介绍了传统TPA、工况TPA、OPAX、快速TPA、多级TPA以及混合TPA的基本原理和优缺点,结合实例说明实现过程,并进行综合比较得出各种方法的应用场合,最后对TPA方法的未来发展作了展望。     

P－S－N曲线测定法比较研究

本文介绍了七种测定Ｐ－Ｓ－Ｎ曲线的方法。并且用五种材料的实验数据对上述测定方法作了分析比较。在比较了几种方法的优缺点的基础上，提出了选择试验方法的建议和结论。