共查询到20条相似文献,搜索用时 15 毫秒
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《Education, IEEE Transactions on》1967,10(1):29-36
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. 相似文献
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《Magma (New York, N.Y.)》1999,8(1):6-10
Magnetic Resonance Materials in Physics, Biology and Medicine - 相似文献
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《Magma (New York, N.Y.)》1999,8(1):102-106
Magnetic Resonance Materials in Physics, Biology and Medicine - 相似文献
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Stefano Giordano 《International Journal of Circuit Theory and Applications》2005,33(6):519-540
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. 相似文献
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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. 相似文献
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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. 相似文献
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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。 相似文献
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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。 相似文献
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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. 相似文献
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电动机试验数据拟合算法的研究与实现 总被引:1,自引:0,他引:1
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. 相似文献
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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。 相似文献
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