采用梁型载荷传感器改造旧式万能试验机

采用弹性梁对旧式液压万能材料试验机下横梁进行改造,为确保弹性梁传感器的灵敏度和精度,根据应用"应力集中"的设计原则,在合理选择传感器结构基础上,采用有限元法对其应变和强度进行计算,合理确定弹性梁的贴片部位,从理论上确定传感器的最大应变方位及传感器的量程。在旧式液压万能试验机上实际应用表明:被测力与输出信号保持严格的对应关系,传感器完全满足测试强度与灵敏度的要求,可实现载荷的电量输出。     

A new approach for ME image restoration based on CNN

A new approach for image restoration by cellular neural network (CNN) is developed in this paper. Based on the statistical characteristics of Gibbs image model and the analysis of maximum entropy (ME) image restoration, a reasonable template for binary image restoration is proposed. To process multilevel image, a multi‐layer cellular neural network is employed and an extensive algorithm for multilevel image restoration is proposed. The results of computer simulation prove the effectiveness of this approach and show that we can get the effective template of CNN for some special image questions if we apply the statistical characteristics of Gibbs image model and analyse the physical meaning of the questions. Copyright © 1999 John Wiley & Sons, Ltd.     

A new approach for edge detection of noisy image based on CNN

A new approach for edge detection of noisy image by cellular neural network (CNN) is proposed in this paper. In order to get the reasonable template, the statistical characteristics of image are utilized, and Gibbs image model is employed to describe the stochastic dependence of an edge pixel on its neighbourhood. Based on stochastic edge image models, edge detection of noisy image is equivalent to seeking a minimum of a cost function. If the template of CNN is designed carefully, the energy function can be mapped properly to the cost function of stochastic edge image model, then CNN can be used for seeking the minimum of cost function. Genetic algorithm is efficient in the field of optimization, and we also utilized this algorithm to get the correct form of template. The results of computer simulation confirm that the new approach is very effective. Furthermore, this result also confirms that we can design template for many different questions based on statistical image model, and the area of application of CNN will be widened. Copyright © 2003 John Wiley & Sons, Ltd.     

Printed circuit board inspection using image analysis

Computer vision has been widely used in the online inspection of electronic components. In this paper, the authors present a computer vision system using structured lighting, which provides them with an efficient solution for solder joint inspection. Their system uses a novel structured-lighting inspection technology to overcome some difficulties that traditional computer vision systems often experience. They developed a slant map surface shape estimation technique for the solder joint. From this technique, a solder joint can be determined to be a good (concave), bad (convex), bridged solder joint, or solder joint with surplus solder, or lacking solder     

A method for analysis of back-swing phenomena of synchronous machine in multimachine power systems

This paper describes a new approach to the analysis of the back-swing phenomena in multimachine power systems. When a short-circuit fault occurs in a power system, some generators decelerate in a short period immediately after the fault in some cases. The phenomenon called back swing is caused by the transient responses in armature winding of synchronous machines and in transmission lines. To represent the back swing in detail by a mathematical model, these transient behaviors have to be described by sets of differential equations. Then not only does the order of differential equations increase, but the convenient expression of the transmission system by a set of node equations becomes useless. In this paper an equivalent power system model for the simple representation of the back swing has been proposed. First, an impedance for each machine that represents the transient of transmission system has been introduced. It is assembled into the differential equations associated with armature winding response. Then the transmission system is represented by a constant impedance matrix. This model makes it possible to calculate the transient behavior of armature flux in multimachine power systems. The transient torque brought to the rotor shaft by the flux is calculated directly and it represents the back-swing phenomena effectively.     

Stabilization control of multi‐machine power systems by adaptive power system stabilizer using frequency domain analysis

To improve electric power system transient stability, synchronous generators are generally equipped with controllers such as AVR, PSS, and GOV. Fixed parameter controllers degrade control performance, since various oscillation modes occur depending on system conditions. This paper presents an adaptive power system stabilizer (PSS) using frequency domain analysis for improving the transient stability of a multimachine system. In the proposed method, first, the frequency components of the generator swings are detected by the FFT. The conventional PSS parameters are tuned online by a fuzzy controller and frequency domain analysis. We verify the proposed adaptive PSS using frequency domain analysis, which can damp the generator swings effectively. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(2): 10–20, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10129     

Methods for remote monitoring and defectoscopy systems for electrical machine high-voltage insulation by using an optical radiation

Experimental results applied to an electron-optical system sensitive to the ultraviolet (UV) and visual spectra are presented. This system makes it possible to detect defects in electrical equipment at the stage of its being created and to estimate equipment reliability. The idea of the diagnostic technique is to record the electromagnetic radiation in the ultraviolet spectrum band if surface partial discharge and corona discharges appear.     

An optical fiber sensor for biofilm measurement using intensitymodulation and image analysis

The development of an online sensor to determine the fouling properties of aqueous process fluids is described. A plastic optical fiber with its cladding removed over a sensitized length measures the growth of biofilms in a closed loop water process system by evanescent field attenuation and intensity modulation. The sensor detects material build-up at the core-cladding interface by means of refractive index modulation. A theoretical model is developed showing that an increase in cladding refractive index reduces the intensity of light propagating in the fiber and attenuates the high order modes. The modulation mechanism of the sensor is demonstrated using a CCD camera and frame grabber to record the far field modal distribution of the fiber, when the outer modes are excited. The intensity distribution changes spatially in response to the biofilm deposit on the sensor, indicating evanescent field attenuation     

Optimization of support insulators used in HV systems using support vector machine

In this paper support vector machine (SVM) has been used for optimization of electric field along the support insulators used in high voltage (HV) systems. To illustrate the effectiveness of SVM in optimizing electric field problems, two axi-symmetric cases have been considered one having an insulator with a contour that is quarter ellipse and the second one having a porcelain core solid insulator. The training and the test data for the SVM have been prepared by electrostatic field computation using indirect boundary element method (BEM). It is observed that once the SVM is trained it is able to give results with mean absolute error of less than 1.5% when compared with the analytically obtained results. The SVM designed for insulator contour optimization is first trained with the results obtained from electric field computation for some predetermined contours of the arrangements under consideration. Then the trained SVM is used to produce an optimized insulator contour in such a way that the desired stress distribution can be obtained on the insulator surface. The results obtained from the present study show that the trained SVM is adequately efficient to optimize insulator contours in order to have the desired stress distribution along the insulator surface     

Optimal power system stabilizers for multi machine systems

Excitation supplementary control is used in power systems to enhance the damping of low frequency oscillations due to the mechanical modes of the generators. Traditionally, frequency deviation is fed back to the exciter through phase lag-lead compensators to form the supplementary control. This supplementary control is known as power system stabilizer (PSS). An optimal power system stabilizer (OPSS) based on linear quadratic regulator design and utilizing the conventional phase lag-lead structure of PSS is presented in this paper. Furthermore, a suboptimal power system stabilizer (SOPSS) is proposed by neglecting the coupling gains between machines and feeding back only the speed deviation and the PSS states. The OPSS and SOPSS are compared with the conventional phase lag-lead power system stabilizer and simulation results of several power system examples are presented.     

基于通用距离测量的机器学习方法用于图像分类和聚类

针对图像分类识别问题,提出了一种用于图像特征提取的新方法.首先定义了基于图像字符串的复杂度和以及通用图像距离(UID),然后依次提出了测量通用图像距离的UID距离测量算法,在维持特征类别之间的固有差异条件下对图像原型进行选择的原型选择算法,利用原型选择算法创建图像的特征向量表示从而生成待分类图像的特征向量的特征向量生成算法,最后基于前述算法提出了对图像的感兴趣区域进行分离的图像分类学习算法.将所提出的方法应用于卫星图像数据的几个监督和非监督学习实验,结果表明文中所提方法效果理想.     

面向对象的锅炉热力故障诊断分析软件

我国许多电站锅炉都存在一定的热力故障问题 ,因而直接影响到电厂的安全经济运行。以 SG5 0 41 4( 42 0 t/h)型锅炉为研究对象 ,采用面向对象语言 Visual Basic与结构化语言 Fortran进行混合编程 ,开发了基于 Windows的面向对象的锅炉热力故障诊断分析软件 ,为电站锅炉的热力故障诊断与分析提供了新的手段     

Monitoring HVDC systems using wavelet multi-resolution analysis

The paper presents a disturbance classification technique based on wavelet multi-resolution analysis. The wavelet multi-resolution transform is introduced as a tool for providing discriminative, translation-invariant features with small dimensions to classify different disturbances in an HVDC transmission system. The proposed method extracts features from signals monitored on both DC and AC sides of the HVDC system. It is shown that monitored signals show promising features that can classify different disturbances that may occur anywhere in the HVDC system     

Analogic CNN algorithms for 3D interpolation-approximation and object rotation using controlled switched templates

Analogic CNN algorithms are presented for various interpolation and approximation tasks in 3D. They are designed on the basis of mechanical analogies. Symmetric space-variant operations are implemented by the CNN algorithms; with switched templates, a key example is object rotation. Direction and speed coding are shown in detail.     

高压直流输电系统中换相失败Hypersim仿真分析

Hypersim是一套功能强大、接口方便、适应性广的全数字实时仿真系统,它能为HVDC换相失败问题的研究提供快速、灵活和准确的电磁暂态仿真。基于Hypersim建立了单极12脉波HVDC系统的详细模型,并分析了一次系统和控制系统的具体结构。对逆变器交流母线发生单相接地短路和三相接地短路故障的情况进行了仿真计算,研究换相失败的判定依据。仿真结果表明,Hypersim能够准确模拟HVDC系统发生换相失败情况,以及通过在控制系统中实施保护控制,能有效抑制换相失败的发生。     

A new fault location algorithm using direct circuit analysis for distribution systems

The unbalanced nature of distribution systems due to single-phase laterals and loads gives difficulty in the fault location. This paper proposes a new fault location algorithm developed by the direct three-phase circuit analysis for unbalanced distribution systems, which has not been investigated due to high complexity. The proposed algorithm overcomes the limit of the conventional algorithm, which requires the balanced system. It is applicable to any power system, but especially useful for the unbalanced distribution systems. Its effectiveness has been proved through many EMTP simulations.     

Time domain analysis of linear systems using spreadsheets

In this paper, a method for the analysis of linear systems using spreadsheets is presented. This method is based on a spreadsheet pictorial simulation of the mathematical performance of an integrator. At first, a connecting method, using integrators, is used to symbolize different blocks of the system each representing a given transfer function. These blocks are then connected according to the signal flow and the interrelationship existing between them. As a result, the output of the system in response to any given input and any given configuration is evaluated. This method is characterized by its low cost, flexibility, and simplicity     

Thermal image analysis for polygraph testing

We have designed, developed, and tested a very promising thermal image analysis method for polygraph testing. The method achieved a correct classification rate of CCR= 84% on the test population to our avail. This method, once refined, can serve as an additional channel for increasing the reliability and accuracy of traditional polygraph examination. We extract subtle facial temperature fluctuation patterns through nonlinear heat transfer modeling. The modeling transforms raw thermal data to blood flow rate information. Then, we use the slope of the average periorbital blood flow rate as the feature of a binary classification scheme. The results come to support our previous laboratory findings about the importance of periorbital blood flow in anxious states.