Least-Squares Curve Fitting and Discrete Optimum Fitting

This tutorial paper presents an introduction to leastsquares curve fitting and its connection to optimum filtering, using methods familiar and appealing to communication and control system engineers and educators in these disciplines. A development of the remarkable computational contribution of Kalman and Bucy to the solution of the Wiener filtering problem is presented, using leastsquares techniques and the Bayesian rule. Since the approach is discrete, the paper stresses the role of the modem digital computer in solving this class of important electrical engineering problems.     

Methodology: perfusion and diffusion

Magnetic Resonance Materials in Physics, Biology and Medicine -     

Brain: perfusion and diffusion

Magnetic Resonance Materials in Physics, Biology and Medicine -     

光缆架空金具的试制

针对光缆通信的特点及优越性,分析了光缆架空金具的现状及发展。为配套架空光缆的安装。介绍了悬垂线夹、耐张线夹、防振锤等的研制,并着重对防振锤的选择进行了计算。根据目前国内外利用电力线路资源开发光缆通信电路的光缆结构形式,为完善配套产品提出了结合市场需求要做的工作。     

Perfusion and diffusion imaging

This article reviews the measurement of perfusion and diffusion and discusses the implications of the observed anisotropy of diffusion of water molecules in some tissues. An experiment is described which shows how observations of diffusion anisotropy can be used to obtain structural information for a model system and to estimate tissue propertiesin vivo. Differences between perfusion and diffusion are highlighted, and the impact of the former on temperature measurementsin vivo based on MRI is discussed. The article concludes that the observation of these phenomena are worth very substantial effort in order to elucidate a number of quite significant problems in the practice of magnetic resonance imaging today.     

Fitting the Russian power industry with automated control systems: New challenges and new solutions

The main results of activities accomplished by the Interavtomatika Company for the last five years are presented. The problem of alternating the generations of applied computerized automation systems is considered. The effect the situation in the energy market has on the solutions for fitting power equipment with automation systems is shown. Special attention is paid to the problem concerned with participation of power units in controlling the operating parameters of power systems.     

光伏阵列区域特性曲线拟合与预估算法研究

介绍一种高精度的光伏阵列区域特性模型。首先采用不同的算法模型对光伏阵列实测IV数据进行拟合,分析比较各种模型的精度水平。推广模型的适用范围,加入环境因素的影响,基于上述各种算法模型对光伏阵列区域特性进行预估研究。通过实验结果对照分析,得到满足工程应用精度要求的实用预估模型,此模型仅采用实测的Isc、Voc、Im、Vm作为参数,便可测得任意环境下的光伏阵列区域特性。光伏阵列区域特性模型及测试的研究能有效地评估光伏阵列的性能,为光伏系统设计需要提供依据,便于光伏系统的开发和利用。     

瞬态过电压波形的滤波、重建与拟合

在测量电力系统瞬态过电压时,分压器的响应特性、测量和采样中产生的误差及各种背景噪声的干扰,很容易导致实际测量得到的波形产生畸变,从而影响对波形的观察与分析。为此,提出了一套解决上述问题的方案:先通过对实际测得的波形进行离散Gabor滤波,去除采样误差与背景噪声引入的畸变;再经过Wiener反卷积,消除分压器响应特性引入的畸变,从而较好地还原原波形;最后通过该方案中的波形拟合功能,更直观地得到各种参数,从而更便于分析。对IEC1083-2TDG(Test Data Generator)所产生的波形进行的测试结果证实,该方案具有上述功能,并具有相当的准确性与稳定性。     

Fitting Russian power units with automated control systems: Development trends, problems, and prospects

The main lines in the development of systems for automated control of Russian power equipment, namely, improvement of technical means and enhancing the level to which technological processes are automated, are discussed. Ways for solving problems concerned with construction of modern automated process control systems, such as use of intellectual field devices, methods for implementing the controller level in a distributed configuration, and integration of local automatic control systems are analyzed. Positive experience gained with achieving a high level of fitting new combined-cycle power plants with automatic control systems and with modernizing the monitoring and control systems of existing traditional equipment is presented. Factors that in some cases do not allow a real technological effect to be obtained from the use of microprocessor process control systems in retrofitted power units are pointed out.     

电动机试验数据拟合算法的研究与实现

电动机数据处理问题在电动机设计中占有重要的地位,对其进行系统的分析具有重要的意义.在数据处理中,通常采用多项式的最小二乘法或根据假设的函数关系来拟合性能曲线;但当多项式的次数较高时,方程组易出现病态等问题.为解决这一问题,采用正交函数作最小二乘拟合的方法绘制电动机性能曲线. 实践证明,该方法简明,结果准确,可应用于测量数据的处理和研究.     

青海电网金具失效分析研究

电网金具的失效断裂直接影响着电网的安全运行,对电网用户的可靠供电和电网设备的健康状态构成了巨大威胁,文章通过近几年来青海电网金具断裂的事例原因分析,提出了金具失效断裂的防范措施。     

ADSS自承式光纤金具的研制与应用

结合光纤通信对通道建设的要求,提出并论证ADSS光纤金具的技术要求、结构型式、材质、尺寸和试验要求,以达到预测目的。     

SiC MOSFET功率器件特性参数的提取与拟合

为了对碳化硅(SiC)MOSFET功率器件的特性参数进行全面的研究,提出了一种碳化硅(SiC)MOSFET变温度参数模型,该模型考虑了功率器件中封装引脚寄生电感、内部寄生电容、体二极管等特性参数,并根据器件的开关过程中的不同阶段,将功率器件中的导电沟道等效为不同电路模型.为获取该模型中的涉及的特性参数,搭建了基于Agi...     

基于曲线拟合的PEBB单元散热优化设计

散热优化是功率电子元组件(PEBB)设计的关键环节,良好的散热系统可充分提高PEBB的功率密度,最大限度地提高开关器件的利用率。文中详细计算了PEBB单元开关器件的各项损耗功率,并采用ICEPAK软件对该单元进行散热仿真分析。通过改变PEBB单元中散热器的翅片数目和基板厚度等参数,得出其对单元散热效果的影响,运用曲线拟合的方式确定了这些影响因素与散热效果的函数关系,并通过对函数式求极值给出了散热器结构优化方案,最终通过对比仿真结果与实验数据验证了热仿真设计方法和实验的一致性,证明了该仿真在系统散热优化设计中具有指导意义。     

基于各向异性扩散的图像降噪算法综述

系统介绍了基于各向异性扩散的图像降噪技术的发展.将各向界性扩散模型分为针对普通噪声和斑点噪声降噪两大类,阐述了在其发展过程中出现的较典型模型的原理、方法和特点.通过试验全面比较了这些模型在降噪、边缘定位、结构保持方面的优劣,分析了该领域亟待解决的关键问题和发展趋势.     

皮带秤实煤校验装置的设计安装

论述了皮带秤是火力发电厂用煤计量的主要手段，其准备性直接影响电厂的经济计算，实煤校验是皮带秤目前最准确的校验方法。另外详细介绍了实煤校验装置的设计思想和在设计安装过程中的注意事项。     

水轮机综合特性曲线的数据拟合及其软件开发

利用软件开发工具Delphi2007和数据库Access2003开发出界面友好、操作简单、接口丰富、通用性较强的特性曲线图采集软件。在Delphi中利用ActiveX技术实现Matlab的自动化,从而在MATLAB中实现对水轮机特性曲线数据的拟合,并将结果反馈到Delphi界面中。该软件可用于水电站计算机仿真、水轮机工况分析等。     

改进加窗频谱峰值拟合算法及谐波分析应用

加窗FFT是目前应用最为广泛的谐波分析方法。但非同步采样时,离散频谱校正中存在计算准确度与实时性的矛盾。论文结合三角自卷积窗的频谱特性,建立了基于最小二乘法的三角自卷积窗加权电力谐波分析算法。首先利用三角自卷积窗对信号进行加权,以抑制频谱泄漏;其次,采用最小二乘法进行离散频谱校正,构造可以根据精度要求进行调节的频谱校正拟合多项式;最后,根据最小二乘拟合多项式,建立简单、易行的谐波幅值、初相角和频率计算式。非同步采样和非整数周期截断条件下,对白噪声、基波频率波动等情况的谐波参数分析仿真实验验证了算法的有效性和准确性。