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A new harmonic power standard has been developed at the National Institute of Metrology (NIM), Beijing, China, for the calibration of harmonic power analyzers under nonsinusoidal conditions at fundamental frequencies of 50 and 60 Hz. The standard is based on digital sampling techniques that do not require synchronization. A compensation algorithm is presented in this paper. A new definition of the...
The current methods of mobile target detection of video sequences have shortcomings such as poor disturbance-resistance and robustness. To solve this problem, a modified GVF Snake algorithm was presented, new gradient vector field was founded which took full advantage of image gradient information, between-frame motion information and grey-level information of neighbor pixels. Simulation result indicates...
Efficient and precise compensation of the range cell migration (RCM) effect is a key point for a fast and accurate synthetic aperture sonar (SAS) data processor. In particular, the range dependent nature of RCM complicates the compensation operation. It has been recently shown that an exact compensation of the range dependent RCM phenomenon can be carried out by applying the chirp Z transform procedure...
According to equity theory, perception of distributive justice is determined by referent. Based on social comparison theory, the referent information can be organized into three categories: information of average (IA); information of better paid referent (IB); and information of worse paid referent (IW). For the purpose of testing the effect of multiple referent information on the perception of d...
Ocean energy generation is a project of great potential on renewable energy at inshore areas. It could not only alleviate the press of power energy at these relative-developed areas, but also give the promotion of sustainable development for environment. Great attention has been given by many countries. This paper analyzes the necessity of the development of ocean energy generation with the world's...
Wind power generation has developed fast in recent years, which not only alleviate the press of power energy, but also give the promotion of sustainable development for environment. China is rich in wind energy resources. The development of wind power in china has made marked progress, although there are some problems. This paper elaborates the importance of the development of wind power; provides...
With the rapid development of the global economy, energy demand of the world is increasing fast. Faced with the exhaustion of the limited non-regeneration energy, the renewable energy, which is characterized by cleanness, safety, and large quantity, has drawn more and more attention. Firstly the advantages and the development of renewable energy for power generation in our country are introduced in...
In this paper an image authentication scheme is proposed to locate tampered area correctly and accurately on the watermarked image. Semi-fragile watermarks are extracted from detail coefficients of wavelet transform and embedded into DCT coefficients. In order to enhance the security, chaotic sequence is employed to encrypt the watermark signals. Experimental results show the proposed technique is...
This paper introduces a new kind of optical current transducer and its application in measuring high voltage DC and AC in power system. To solve the long-term operating stability and the steady state metering accuracy which influence the practical course of OCT, this paper presents a new method which combines the lock-in amplifier in slight photo-electric signal detection and a new higher stability...
The precision measurement for harmonic current and power up to 60th order and some validating experiments is reported. The uncertainty of harmonics current reference to fundamental is less than 36 muA/A (k=2) for range up to 50 A. The uncertainty of harmonic power reference to the fundamental apparent power is less than 42 muW/VA (k=2) for voltage and current range up to 500 V and 50 A.
The workload of calibrating equipment for AC electrical energy meters is getting more and more heavy. One subject is put forwarded which is using internet to carry on long-distance calibration. The system's designing theory, testing procedure, utilization of software and hardware hanged together are described particularly in this paper.
The uncertainty of phase shift determined through DFT of sampling data for the voltage dividers and shunts in the harmonic power standard at NIM is reported.
A definition for uncertainty of harmonic voltage is proposed. A conception of "characteristic signal" is discussed for digital estimation of equipment. The experimental determination for the uncertainty sources such as leakage, noise and non-linearity from frequencies are reported. Within the 60th harmonic up to the range of 500 V, the uncertainty reference to fundamental is less than 30...
For calibration of analyzer of harmonic voltage, current and power under non-sinusoidal condition at fundamental in industrial frequency, a harmonic power standard has been built at NIM, in which non-integer-period sampling is applied. Its setup, algorithm, and whole uncertainty are reported.
A new approach to determine phase-shift of shunt based on the sampling measurement and substitution method is described with theoretical analysis and test results. The differences with SP's results are within 2 murad at fundamental wave of 50 Hz and within 30 murad at 30th harmonic.
This paper investigates topology control and seeks to find a distributed solution with low interference, high performance. The paper proposes a distributed topology control algorithm called CBDTG by using the method of adjusting transmission power and the achievements of computational geometry, especially Delaunay triangulation (DT). Each node in the network invokes the neighbor discovery process...
Time interleaving technique is a significant trend in performance enhancement for high-speed ADC systems. This paper presents an ADC card based on time-interleaving technique. The system uses two 8-bit ADCs in parallel. Each ADC can sample at 250 MHz and the total sampling speed will theoretically becomes 500 MSPS. In an approach to increase the system's performance, a calibration algorithm is developed...
Although pay strategy is an important aspect in organizational strategic management, its effect on employees' pay satisfaction is unclear yet. In This paper, the effect of pay strategy on employees' pay satisfaction was examined by a simulative experiment, which was based on the Adams' equity theory. 122 MBA students participated in the study, and a single-factor completely randomized design was employed...
This paper is mainly about sensorless brushless DC motor (BLDCM) controlling system based on MRAC method, which substitutes the traditional controlling system, the problem of hall tracking err when running at low speed is solved. In addition, a new Hall sample circuit is designed and analyzed. By the virtue of overcoming the disturbance of hall that causes the wrong actions of the controlling circuit,...
Controlling system is the core of electric vehicles. Performance of the controller determines the character of the whole system. Based on the research of driving and regenerating circuit topology for permanent brushless DC motor (BLDCM), regenerating braking electric vehicle controller is designed. In order to improve the stability and reliability of the system, fuzzy-sliding mode control algorithm...
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