Power calibrator using switched mode voltage source

The paper is focused on a sophisticated switched mode power supply with a pure sinusoidal output voltage waveform with frequency (40-65 Hz) and voltage range (30-500 V). In order to cope with stringent voltage (10.2%) and distortion constraint (THD<0.7%) in a modern calibration system, traditional inverter design with an output LC filter is upgraded with a feedback-feedforward control principle. The paper presents the voltage source topology, analyzes its steady-state response and gives its comprehensive evaluation. Using a simple sensor that is capable to detect a small voltage asymmetry at the presence of a high AC component (500 VRMS), the parasitic DC component is limited below 5 mV. Experimental results demonstrate exceptional voltage accuracy (<0.2%) and low total harmonic distortion (THD)     

The N5-4 high-frequency voltage calibrator

The main characteristics, constructional features, and recommendations on the use of a new measuring instrument, employed as a highly stable multivalued standard of a variable high-frequency voltage, operating in the 0.1–50 MHz frequency band and at voltages of 0.166–30 V, are described. __________ Translated from Izmeritel’naya Tekhnika, No. 3, pp. 40–43, March, 2008.     

High-temperature superconducting SQUID as calibrator of ac voltage dividers and LF voltmeters

The performance of a radio-frequency SQUID made of high-temperature superconducting ceramics as a calibrator of ac voltage dividers and LF voltmeters at frequencies up to 1 MHz is investigated. The measurement technique and errors are analyzed. The obtained results suggest that in principle the high-temperature superconducting device can reproduce the voltage divider scale with an error less than 10^–3 dB within an input signal range from several microvolts to several volts.Translated from Izmerital'naya Tekhnika, No. 9, pp. 47–50, September, 1995.     

非负矩阵分解的分布式算法

提出一种解决大规模非负矩阵分解的分布式算法.非负矩阵分解一直是矩阵分解领域中的热点问题之一,已有一些相关的算法.但是,对于大规模的非负矩阵,至今尚无高效的方法.本文采用近来解决大数据的分布式思想和并行式计算方法,并将它们与传统的矩阵分解算法相结合,提出一种基于并行式计算的分布式网络算法,以此实现大规模的非负矩阵分解问题.实验结果表明,所提出的算法较一般的分布式算法与集中式矩阵分解的算法更加有效和快速.     

A gain monitor and calibrator for a single-channel pulse height analyser

A monitoring NIM module that visually displays the peak position and facilitates the calibration of the single-channel pulse-height analyser used in the counting of nuclear-radiation particles, has been developed. The module includes a visual 100-point bar graph array, which presents any peaks in a given spectrum with greater intensity than that of the background. A gating circuit that accepts the early or late generation of logic pulses from a single-channel analyser enables the display of the window to be set by the single-channel analyser.     

A new heuristic algorithm for capacity planning in a manufacturing facility under learning

In this paper, a new and efficient heuristic algorithm is presented to determine the production capacity in a new facility under the effect of learning. Different demand patterns are studied while deciding the capacity requirements. Further, the learning effects due to human-machine interaction often found in a manufacturing system are considered during the development of the model. A computer program is developed and interfaced with XMP software on a Sun 3/60 workstation. Several numerical examples are presented to illustrate the heuristic algorithm.     

Design and evaluation of a compensating algorithm for the secondary voltage of a coupling capacitor voltage transformer in the time domain

This study describes the design and evaluation of a compensating algorithm for the secondary voltage of a coupling capacitor voltage transformer (CCVT) in the time domain by considering the hysteresis characteristics of the core. The major error of the CCVT is the voltage across the capacitor and the tuning reactor caused by a non-sinusoidal exciting current. The proposed algorithm estimates the voltage across the capacitor and the reactor by considering the effect of the hysteresis characteristics of the core and adds it to the measured secondary voltage to obtain the correct voltage. The algorithm reduces the errors of the CCVT significantly both in the steady state and during a fault. The performance of the algorithm is verified under the various fault conditions by varying the fault distance, the fault inception angle and the fault impedance with the EMTP generated data. Test results clearly indicate that the algorithm can increase the accuracy of a CCVT significantly under the fault conditions as well as in the steady state. The algorithm helps to improve the performance of a protection relay or a metering device.     

基于空闲时间分配的电压调节策略

为了求解考虑系统能耗的实时动态电压调节（DVS）问题,提出了基于空闲时间分配算法（STDA）的DVS策略,该策略以时间片为单位逐步把所有空闲时间分配给各个任务,且每个时间片都被分配给产生能量减少量最大的任务。分析指出,当时间片大小设置合适时,STDA算法的能耗接近于DVS问题的最小能耗。仿真实验结果表明,对于仅考虑处理器能耗的DVS问题,STDA算法的能耗和最优策略的能耗相近;而对于考虑系统能耗的DVS问题,STDA算法减少能耗的效果要优于其他现有DVS策略。     

交直流电表校验仪直流电压示值误差测量结果不确定度评定

文章介绍交直流电表校验仪开展校准工作的相关条件,并对其作为相关电参量仪表的检定／校准装置测量结果的不确定度进行评定。     

Binocular self-calibration performed via adaptive genetic algorithm based on laser line imaging

Abstract

An accurate technique to perform binocular self-calibration by means of an adaptive genetic algorithm based on a laser line is presented. In this calibration, the genetic algorithm computes the vision parameters through simulated binary crossover (SBX). To carry it out, the genetic algorithm constructs an objective function from the binocular geometry of the laser line projection. Then, the SBX minimizes the objective function via chromosomes recombination. In this algorithm, the adaptive procedure determines the search space via line position to obtain the minimum convergence. Thus, the chromosomes of vision parameters provide the minimization. The approach of the proposed adaptive genetic algorithm is to calibrate and recalibrate the binocular setup without references and physical measurements. This procedure leads to improve the traditional genetic algorithms, which calibrate the vision parameters by means of references and an unknown search space. It is because the proposed adaptive algorithm avoids errors produced by the missing of references. Additionally, the three-dimensional vision is carried out based on the laser line position and vision parameters. The contribution of the proposed algorithm is corroborated by an evaluation of accuracy of binocular calibration, which is performed via traditional genetic algorithms.     

A digital self-calibration circuit for absolute optical rotary encoder microsystems

The parameters of the analog waveforms produced by the front-end electronics of absolute optical rotary encoders are affected by substantial differences and drifts. The threshold level required to convert the generated analog signal into a digital square wave in each read-out channel has to, therefore, be calibrated so as to keep the output duty-cycle close to its ideal value of 50%. This paper presents a digital self-calibration circuit specifically designed for this purpose. The circuit performs dynamic calculation of the threshold level, continuously compensating for encoder nonidealities while the system is normally operating. This avoids the need for manual calibration, provides thermal stabilization, and prevents performance degradation. The proposed digital calibration system was integrated in conventional CMOS technology and was then successfully evaluated.     

Digital self-calibration method for MEMS sensors

This paper presents a digital self-calibration method for microelectromechanical systems (MEMS) using a relay-feedback loop and a set of discrete-time filters. This method is based on the measurement of limit-cycles at the comparator's output, which result from a synchronization phenomenon between the natural frequency of the MEMS and the clock frequency of the discrete-time components. We show how quantized information concerning the MEMS parameters may be extracted from the shape of the limit-cycle, which depends on the characteristics of the MEMS (pulsation, damping, etc.). This digital technique is amplitude-independent, relatively insensitive to noise, and not costly to implement. Details concerning its implementation are discussed, and some simulation and experimental results are given.     

A buildup voltage distribution (BVD) algorithm for shape control of smart plate structures

 An intuitive approach for the determination of voltage distribution in the application to shape control of smart structures using piezoelectric actuators is presented here. The algorithm called the Buildup Voltage Distribution (BVD) is based on an iterative approach inspired by a combination of existing iterative techniques. The mathematical model of the smart structure is based on a High Order Displacement (HOD) field coupled with a Layerwise Linear electric potential. The current shape control work will make use of the Finite Element (FE) formulation based on the above mentioned mathematical model. The development of the BVD algorithm makes no linearity assumption between displacement and voltage and hence can be applied to non-linear mathematical models. The algorithm will then be compared with two well-known algorithms. In addition, a patch insensitivity index is defined to identify the most and least effective locations for piezoelectric actuators. Received: 15 July 1999     

Camera self-calibration method suitable for variant camera constraints

This paper presents a self-calibration algorithm that seeks the camera intrinsic parameters to minimize the sum of squared distances between the measured and reprojected image points. By exploiting the constraints provided by the fundamental matrices, the function to be minimized can be directly reduced to a function of the camera intrinsic parameters; thus variant camera constraints such as fixed or varying focal lengths can be easily imposed by controlling the parameters of the resulting function. We employed the simplex method to minimize the resulting function and tested the proposed algorithm on some simulated and real data. The experimental results demonstrate that our algorithm performs well for variant camera constraints and for two-view and multiple-view cases.     

Application of core vector machines for on-line voltage security assessment using a decisiontree-based feature selection algorithm

This study presents a core vector machine (CVM)-based algorithm for on-line voltage security assessment of power systems. To classify the system security status, a CVM has been trained for each contingency. The proposed CVM-based security assessment algorithm has a very small training time and space in comparison with support vector machines (SVMs) and artificial neural networks (ANNs)-based algorithms. The proposed algorithm produces less support vectors (SVs). Therefore is faster than existing algorithms. One of the main points to apply a machine learning method is feature selection. In this study, a new decision tree (DT)-based feature selection algorithm has been presented. The proposed CVM algorithm has been applied to New England 39-bus power system. The simulation results show the effectiveness and the stability of the proposed method for on-line voltage security assessment. The effectiveness of the proposed feature selection algorithm has also been investigated. The proposed feature selection algorithm has been compared with different feature selection algorithms. The simulation results demonstrate the effectiveness of the proposed feature algorithm.