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 -     

水位流量曲线BP神经网络逼近与多项式拟合对比

介绍了水位流量曲线的反向传播（BP）神经网络逼近方法,使用MATLAB对逼近精度和误差进行分析;介绍了水位流量曲线的多项式拟合方法,并借助OriginPro分析了拟合精度。从拟合原理、拟合精度、适用场合等方面对这2种拟合方法的优劣进行了对比。     

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。     

Disordered lattice networks: general theory and simulations

In this work we develop a theory for describing random networks of resistors of the most general topology. This approach generalizes and unifies several statistical theories available in literature. We consider an n‐dimensional anisotropic random lattice where each node of the network is connected to a reference node through a given random resistor. This topology includes many structures of great interest both for theoretical and practical applications. For example, the one‐dimensional systems correspond to random ladder networks, two‐dimensional structures model films deposited on substrates and three‐dimensional lattices describe random heterogeneous materials. Moreover, the theory is able to take into account the anisotropic percolation problem for two‐ and three‐dimensional structures. The analytical results allow us to obtain the average behaviour of such networks, i.e. the electrical characterization of the corresponding physical systems. This effective medium theory is developed starting from the properties of the lattice Green's function of the network and from an ad hoc mean field procedure. An accurate analytical study of the related lattice Green's functions has been conducted obtaining many closed form results expressed in terms of elliptic integrals. All the theoretical results have been verified by means of numerical Monte‐Carlo simulations obtaining a remarkably good agreement between numerical and theoretical values. Copyright © 2005 John Wiley & Sons, Ltd.     

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.     

特高压直流试验基地塔型布置及金具设计

我国特高压直流试验基地试验线段和电晕笼的塔型布置应满足试验功能要求,共规划设计了7 种基本塔型,9 基铁塔。在金具选择方面, 导线悬垂串由于要安装测试用阻波器, 故选择V 串+耐张串形式, 采用合成绝缘子; 导线耐张串采用双挂点, 以合成绝缘子型式为主, 为了试验需要还配有瓷绝缘子型式, 耐张串采用卡盘形式的金具将绝缘子串和导线连接起来; 导线引流串主要为I 串形式, 分单线夹和双线夹2 种; 引流线主要采用φ300mm 的管母线, 个别地方采用8×LGJ- 720 钢芯铝绞线; 管母线的固定采用数根钢芯铝绞线, 满足强度和刚度的要求, 且无需配重。     

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.     

我国架空输电线路金具技术发展及应用

电力金具是国家实施生产许可证管理的产品,其设计制造水平随着特高压输电技术的发展有了很大提高。文中介绍了当前电力金具产品执行标准、设计水平、材料与加工工艺以及铝合金悬垂线夹、碳纤维芯导线耐张线夹、回转式线夹间隔棒、预绞式金具、大跨越金具等典型产品的结构形式与应用,并对产品技术标准和企业质量管理存在的问题提出了一些改进和建议。     

水库容积特性曲线定线及其在调度中的应用

发电调度模型中水库容积特性的离散化表征导致调度模型数学解析变得困难和模型求解效率低,而已有研究对水库容积特性的函数化表征缺乏统一性,有必要开展水库容积特性曲线定线研究.本文基于水库水位-库容实测离散数据点,通过线性和非线性最小二乘拟合获取不同线型的水库容积特性曲线,并对不同线型容积特性曲线的拟合优度及工程应用效果进行综...     

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.     

电缆护套环流估算公式的拟合及排列方式的优化

护套交叉互联双端接地电缆中,3段电缆长度不均等,或电缆排列方式不对称,均会导致金属护套中产生环流。文中分析了排管敷设的单回路交叉互联电缆金属护套感应电压相量和,采用EMTP模型仿真不同的电缆分段长度差下的金属护套环流,得到EMTP仿真数据样本,用来拟合金属护套环流估算公式,最后将拟合的估算公式计算值与EMTP仿真数据进行对比,检验了估算公式的适用性。此外,还分析了不同排列方式感应电压相量,提出并验证了在不等长分段电缆中,采用恰当的混合排列方式可以降低金属护套环流。     

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。