谐波信号检测及经济评估

本文分析了一种神经元自适应谐波电电流检测方法提出了谐波的经济评估方案。

深圳市部分厂矿噪声作业人员听力检测结果与建议

目的了解深圳市部分厂矿企业在岗噪声作业人员及上岗前工人听力损伤情况。方法用VO-522型电测听仪对接触和准备接触噪声的工人进行检测,在岗期间噪声作业工人检测多在厂区,现场离噪声源较远、环境较安静的地方进行;就业前职业禁忌证检测在隔音室内进行。结果两组检测资料显示,噪声的职业危害与年龄和性别无关;在岗期间接噪组听力下降随着接触噪声工龄的增长呈上升趋势(χ2=21.99,P<0.01))。在岗期间组和就业前组听力下降率,两组之间差异有统计学意义(χ2=5.06,P<0.05)。结论噪声对作业工人听力有损伤。现场电测听检测既方便了企业的生产,又提升了职防工作的效率。

关于高压电气设备的绝缘预防性试验研究

电气设备绝缘安全与电力系统安全密切相关,阐述对高压电气设备进行绝缘性能预防性试验的必要性和试验的内容,对试验影响因素进行总结,并说明了试验分析方法。文章还提出,在试验中应做好安全管理,保证人员和设备安全。

永磁式励磁器结构参数设计

分析了钢丝绳损伤电磁检测的永磁式周向励磁回路，提出了励磁回路的等效磁路模型，推导了磁路参数的计算公式，计算出磁路中不同气隙对应不同直径钢丝绳所需要的磁势降。对直径10～60mm的钢丝绳进行饱和磁化所需的励磁回路参数和励磁器结构尺寸进行设计计算，为钢丝绳损伤电磁检测的励磁器设计提供了理论依据。

Adaptive double-threshold energy detection algorithm for cognitive radio

Due to the fact that the conventional spectrum sensing algorithm is susceptible to noise, an adaptive double-threshold energy detection algorithm for a cognitive radio is proposed. Based on double-threshold energy detection, the algorithm can adaptively switch between one-round sensing and two-round sensing by comparing the observations with the pre-fixed thresholds. Mathematical expressions for the probability of detection, the probability of false alarm, and the sensing time are derived. The relationships including signal to noise ratio （SNR） vs. the probability of detection and SNR vs. the sensing time are plotted using Monte Carlo simulation and the algorithm is verified in a real cognitive system based on GNU Radio and universal software radio peripheral （USRP）. Simulation and experimental results show that, compared with the existing spectrum sensing method, the proposed algorithm can achieve a higher probability of detection within a reasonable sensing time.

Design of intelligent line-tracking chess robot based on STM32

An intelligent line-tracking chess robot based on STM32 is introduced in this paper. Its hardware consists of photo- electric detection circuit, main control circuit, motor driven circuit, steering engine driven circuit and dial switch. The hardware structure and software flow chart of the system are described in details in this paper. The robot is driven by rear wheel motors, and the real-time position of the robot is determined by the ground information collected by infrared sensors. The heading direction of robot is adjusted by steering engine installed in front wheel, and the open angle of manipulator is controlled by the other steering engine which can ensure the robot moving chessmen accurately and quickly during the moving process. The test shows that the kind of intelligent chess robot can complete the task in a fast and accurate way.

A FAULT DETECTION SENSOR FOR CIRCUIT AGING USING DOUBLE-EDGE-TRIGGERED FLIP-FLOP

In nanoscale technology, transistor aging is one of the most critical problems that impact on the reliability of circuits. Aging sensor is a good online way to detect the circuit aging, which performs during the operating time with no influence of the normal operation of circuits. In this paper, a Dou- ble-edge-triggered Detection Sensor for circuit Aging （DSDA） is proposed, which employs data signal of logic circuits as its clock to control the sampling process. The simulation is done by Hspice using 45 nm technology. The results show that this technique is not case of the detection precision is more than 80% under aging fault effectively with the 8% power cost and 30% sensitive to the process variations. The worst the different process variations. It can detect performance cost.

Design of Photoelectric Detection Circuit in Linear Measuring System

The structure,equivalent circuit,noise sources of silicon photodiode are analyzed.In order to improve the measuring linearity,we must choose the silicon photodiode with a large R d,small R s and I 0 and under an operation state of output short-circuit.We must let the operation amplifier work in the current-voltage transfer form.Also we analyzed the effects of the input noise voltage,the input noise current,the input offset voltage,the input offset current of the operation amplifier and the noises of the silicon photodiode on the combined circuit of the operation amplifier with the silicon photodiode.Considering these factors,we can design the detective circuit with high response,sensitivity,stability,linearity and SNR .

Fluorescence-based Multiplex PCR-Single Strand Conformation Polymorphism (SSCP) Analysis of 16S Ribosomal DNA Using Capillary Electrophoresis

The rRNA genetic locus is found in all prokaryotic organisms, and is highly conservative, although its relatively stable variations are found frequently in different bacteria. The utility of this locus as a taxonomic and phylogenetic tool has been reported widely. This study, aimed at 16S rRNA gene (16S rDNA) and with the help of biomolecular methods, attempted to achieve the goal of rapid identification of common pathogens. In this study, 333 clinical isolated pathogenic bacteria were collected. Two pairs of primers were chosen and labeled with different fluorescent dyes and then used to amplify the genomic DNA extracted from bacteria. The PCR products were then detected by capillary electrophoresis-single strand conformation polymorphism (CE-SSCP). In order to pursue higher resolution and peak-separation effect, a high efficient separating medium, liner polyacrylamidedel (LPA), was put to use in this study. Finally, every bacteria colony generated distinct patterns from each other, which were easily to be used for identification. These results indicated that PCR-CE-SSCP was a rapid identification method for bacterial identification, with the aspects of high efficiency and high precision. Compared with traditional method, this technology is of great utility for clinical use especially for its high sensitivity.

Dynamics analysis of vibration process in Particle Impact Noise Detection

Particle Impact Noise Detection (PIND) test is a reliability screening technique for hermetic device that is prescribed by MIL-PRF-39016E. Some test conditions are specified, although MIL-PRF-39016E did not specify how to obtain these condi- tions. This paper establishes the dynamics model of vibration process based on first order mass-spring system. The corresponding Simulink model is also established to simulate vibration process in optional input excitations. The response equations are derived in sinusoidal excitations and the required electromagnetic force waves are computed in order to obtain a given vibration and shock accelerations. Last, some simulation results are given.

Scanning Measurement Method of Dispersion Mini-spot by Quadrant Photodetector

Quadrant photodetector is a new type position detector, which has already been applied to many fields such as measurement, target tracking, control, laser collimation, guidance, etc. System performance is related to laser spot area received by the quadrant photodetector. The optimum linear output signal of system is gotten only when the size of laser dispersion spot is well-proportioned to the detector photosensitive area. A method to measure the mini-spot received by detector and to adjust it in real time is presented, which is based on the quadrant geometrical and optical structure, making use of tilting mirror scanning, the sequence output signal of detector is gotten, then measurement model is built with rate of signal change as characteristic variable, the radius of the laser dispersion spot and adjustable value of dispersion are calculated. The experiment result shows that the maximum error is 0.58μm in measurement range of 0.5mm±0.1mm.

Development and Optimization of an Alternative Methodology for Detection of Milk Adulteration by Water

This paper presents a process which allows the determination of milk adulteration by water. Considering the limitations of the reference method （cryoscopy）, the proposed methodology matches electrical conductivity and cryoscopy index measurements. Based on statistical procedures, a linear descriptive model is achieved to quantify adulteration of milk with water. It is also shown that electrical conductivity measurements allow the detection of adulteration with water and sodium chloride.

Mitigation of primary user emulation attack using a new energy detection method in cognitive radio networks

A most promising solution to the expansion of spectrum efficiency is cognitive radio(CR)and this expansion is achieved by permitting the licensed frequency bands to be accessed by unlicensed secondary users(SUs)with a lack of interference with licensed primary users(PUs).This utilization of CR networks in the spectrum sensing causes vulnerable attacks like primary user emulation(PUE)attack and here PUs play the role of malicious user and do not permit other users to utilize PUs channel even in their unavailability.On the basis of the traditional single-threshold energy detection algorithm,a novel modified double-threshold energy detector is formulated in the CR network and the detection probability,miss detection probability,probability of false alarm,and their inter-relationship are analyzed.This paper develops a modified double threshold energy detection cooperative spectrum sensing technique to alleviate the PUE attack.Finally,performance-based evaluation is carried out between the proposed and the existing energy detection spectrum sensing method that had no consideration on PUE attack.The resultant of the simulation in MATLAB has revealed that the proposed model has significantly mitigated PUE attack by means of providing outstanding performance.

Determination of Threshold for Energy Detection in Cognitive Radio Sensor Networks

The Internet of Things （loT） is called the world＇ s third wave of the information industry. As the core technology of IoT, Cognitive Radio Sensor Networks （CRSN） technology can improve spectrum utilization efficiency and lay a sofid foundation for large-scale application of IoT. Reliable spectrum sensing is a crucial task of the CR. For energy de- tection, threshold will determine the probability of detection （Pd） and the probability of false alarm Pf at the same time. While the threshold increases, Pd and Pf will both decrease. In this paper we focus on the maximum of the difference of Pd and Pf, and try to find out how to determine the threshold with this precondition. Simulation results show that the proposed method can effectively approach the ideal optimal result.

PDA DETECTOR FOR DS-CDMA COOPERATIVE SYSTEM

This paper considers the uplink of a cooperative Code-Division Multiple-Access (CDMA) system where parts of mobile nodes serve as source nodes while the others serve as relay nodes at any instant in time. When the non-orthogonal spreading codes are adopted,Multiple Access Interference (MAI) will exist at both the relay nodes and the base node,causing diversity gain to diminish. To mitigate MAI and exploit full advantages of cooperation,the Probabilistic Data Association (PDA) is developed at the relay nodes and the base node. Simulation results demonstrate that some performance gains can be obtained by the PDA detector over the Minimum Mean Square Error (MMSE) detector at high Signal-to-Noise Ratio (SNR) and conversely at low SNR.

Research on Testing Technologies of Network System in Smart Substations

The network structures of smart substations and the characteristics of industrial Ethernet switches are analyzed.The testing technologies of network systems based on smart substations are specifically elaborated.A viewpoint is proposed that special testing policy&method of smart substation networks should be followed,so that the results can reveal the real network data exchange performance of the whole station.This view ensures the safety and stability of smart substations and lays a foundation for future upgrades and expansions.

Continuous on-line adaptation of the rotor time constant in FOC induction machine system

Rotor time constant is an important parameter for the indirect lleld oraentateO control of mauc- tion motor. Incorrect rotor tittle constant value will cause the flux observer generating a wrong angu- lar orientation of the rotor field. A new approach serves for rotor time constant on-line adaptation by setting the stator current to be zero for a short period. A smooth eorrector is designed to prevent ab- normal detection result from making adaptation. Impact of zero current duration on detection error and rotor speed is analyzed by experiments.

Application of Holter ECG Signal Analysis Based on Wavelet and Data Mining Technique

A new model based on dyadic differential wavelet was developed for detecting the R peak in Holter ECG signal according to the design of data mining. The Mallat recursive filter algorithm was introduced to calculate wavelet and optimize the detection algorithm which is based on the equivalent filter technique. The detection algorithm has been verified by MIT arrhythmia database with a high efficiency of 99%. After optimization, the algorithm was put into clinical experiment and tested in the Air Force Hospital in Tianjin for about two months. After about 108 hearts beating test of more than 100 patients, the total efficient detection rate has reached 97%. Now this algorithm module has been applied in business software and shows perfect performance under the complex conditions such as the inversion of heart beating, the falling off of the electrodes, the excursion of base line and so on.

Electricity Price Forecasting Based on AOSVR and Outlier Detection

Electricity price is of the first consideration for all the participants in electric power market and its characteristics are related to both market mechanism and variation in the behaviors of market participants. It is necessary to build a real-time price forecasting model with adaptive capability; and because there are outliers in the price data, they should be detected and filtrated in training the forecasting model by regression method. In view of these points, mis paper presents an electricity price forecasting method based on accurate on-line support vector regression (AOSVR) and outlier detection. Numerical testing results show that the method is effective in forecasting the electricity prices in electric power market

Utilization of Data Communication according to the IEC61850 Standard for Nuclear Power Plant Electrical Equipment Testing

This paper deals with an integration of directly measured electrical parameters with data acquired by data communication from protections and terminals into an advanced monitoring system. Based on the periodic test, the authors of this paper present the possibility of an extended evaluation and more accurate analysis of transient and failure events. For periodical testing, as implemented during the commissioning of power plants in the Czech Republic, a monitoring system of electrical equipment has been used, to record the courses of important electrical parameters and thus, proving the proper functioning of complex technological systems in various operation modes. Data from monitoring system were used to prove the successful results of the test or as a base data for further analysis of failures. The monitoring system has proved itself as a very useful device also when recording unexpected failure events, the cause of which was very quickly and accurately detected by the follow-up analysis. Initially, only the voltage and current data from measuring transformers, analogue transducers and contact relays were used as input data for the monitoring system. After the implementation of new digital protection technology and controlling terminals with inner data recorder, the data from digital devices could be also utilized for the monitoring system.