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自己动手制教具 促进实践出真知——自制桑塔纳轿车整车电路操作演示台 被引量:1
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作者 魏开泰 《交通职业教育》 1996年第5期34-35,共2页
为培养能适应现代化建设需要的各类人才,全国各地的职业教育都以很快的速度向前发展。但由于我国职业教育起步较晚,教育经费和教育设备不足,特别是专业课程中实践教育环节比较薄弱,培养出来的学生操作技能和实践能力还很难适应岗位要求。
关键词 桑塔纳轿车 职业教育 实践能力 电路操作 操作演示 设备不足 自己动手 整车 电路 理论知识
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一种电力操作电源的建模与控制环路设计 被引量:3
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作者 刘兴发 文远芳 周挺 《电力电子技术》 CSCD 北大核心 2006年第3期117-119,共3页
结合电力操作电源的特性,建立了基于有限双极性控制的操作电源的小信号模型,并设计了控制电路。克服了开关电源轻载实现零电压零电流开关(Zero-VoltageZero-CurrentSwitching,ZVZCS)效果不好以及传统电压控制模式反应相对较慢的缺陷。... 结合电力操作电源的特性,建立了基于有限双极性控制的操作电源的小信号模型,并设计了控制电路。克服了开关电源轻载实现零电压零电流开关(Zero-VoltageZero-CurrentSwitching,ZVZCS)效果不好以及传统电压控制模式反应相对较慢的缺陷。该电路具有简单、可靠、稳定的特点。 展开更多
关键词 电源 控制电路/电力操作电源 有限双极性控制
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无线传感器网络中FSK的电池能耗分析 被引量:1
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作者 唐秋玲 《科技咨询导报》 2007年第28期13-14,16,共3页
基于无线传感器网络中周期性数据传输的通信任务,本文探讨采用FSK调制技术时两传感器节点之间通信链路上的电池能耗问题,针对不同的电池耗能模型、不同电路操作模式和不同传输信道情况下的电池能耗进行理论评估和数值仿真比较。结果表明... 基于无线传感器网络中周期性数据传输的通信任务,本文探讨采用FSK调制技术时两传感器节点之间通信链路上的电池能耗问题,针对不同的电池耗能模型、不同电路操作模式和不同传输信道情况下的电池能耗进行理论评估和数值仿真比较。结果表明,实际电池能耗总比理想化电池能耗要大;多模式比单模式电路操作节能;在相同的系统参数下,Rayleigh衰落信道环境中的能耗比路径损耗信道中的能耗大得多。 展开更多
关键词 无线传感器网络 频移键控(FSK) 电池能耗 电路操作模式 无线信道
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Tests on the First 500 kV Compact Transmission Line in China 被引量:2
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作者 巩学海 王惠仁 张章奎 《Electricity》 2001年第1期22-27,共6页
The paper deals with the tests on the first 500 kV compact transmission line. The transmission line stretches from Fangshan Substation to Changping Substation nearby Beijing with a length of 83 km. In order to investi... The paper deals with the tests on the first 500 kV compact transmission line. The transmission line stretches from Fangshan Substation to Changping Substation nearby Beijing with a length of 83 km. In order to investigate the characteristics of the transmission line, many tests were performed on the line before and after its operation. The results indicate that all electrical parameters are perfectly identical to the design. 展开更多
关键词 compact transmission line overvoltage switching surge parameters
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Sub-independence-spaces 被引量:2
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作者 MAO Huat WANG Gang 《Chinese Quarterly Journal of Mathematics》 CSCD 2010年第2期293-299,共7页
Cleverly using the relation of independence spaces and B-matroids, this paper firstly deals with the properties of the closure operator of an independence space, followed by presenting the definitions and solving some... Cleverly using the relation of independence spaces and B-matroids, this paper firstly deals with the properties of the closure operator of an independence space, followed by presenting the definitions and solving some relative properties for the sub-independence spaces of an independence space with the help of circuits. 展开更多
关键词 CIRCUIT sub-independence-space independence space closure operator
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Hierarchical Cognition Cycle for Cognitive Radio Networks
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作者 WANG Jinlong FENG Shuo +2 位作者 WU Qihui ZHENG Xueqiang XU Yuhua 《China Communications》 SCIE CSCD 2015年第1期108-121,共14页
Cognitive radio(CR) can bring about remarkable improvement in spectrum utilization.Different cognition cycles have been proposed in recent years.However,most of the existing works only emphasize functional or operatio... Cognitive radio(CR) can bring about remarkable improvement in spectrum utilization.Different cognition cycles have been proposed in recent years.However,most of the existing works only emphasize functional or operational aspects of cognition cycle,regardless of other indispensable aspects and the connection between them.To deal with the emerging situation of "data rich,information vague,knowledge poor" in cognitive radio networks(CRNs),we propose the hierarchical cognition cycle(HCC) as a new transdisciplinary research field in this paper.HCC investigates a fundamental problem,which is how to manage available resources in the complex environment to meet various demands in CRN.A comprehensive theoretical framework of HCC is established in terms of the core,the essence loop,the function loop,the operation loop,and the external loop of HCC.The reduction of uncertainty in CRN is studied and several new metrics in HCC are defined.Furthermore,a few research challenges ahead are presented as well. 展开更多
关键词 cognitive radio network hierarchical cognition cycle theoretical framework UNCERTAINTY research challenge
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A Fuzzy Control Based Intelligent Control System for Flower Greenhouse
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作者 Zou Zhiyong Zhou Man 《International Journal of Technology Management》 2015年第1期80-83,共4页
In order to realize intelligent control of flower greenhouse' s parameters of atmospheric temperature and humidity, lighting intensity, CO2 concentration and soil water content, it carries out design with ZigBee netw... In order to realize intelligent control of flower greenhouse' s parameters of atmospheric temperature and humidity, lighting intensity, CO2 concentration and soil water content, it carries out design with ZigBee network, embedded controller and intelligent fuzzy control algorithm as core. With advantages of high precision and stability, the design of sensor circuit mainly employs digital module sensors. In order to save energy, the sensor circuit is controlled by relay switch to work at the proper time. The gateway node is designed by employing high performance 32-digit embedded controller and WinCE6.0 embedded OS is self customized. And embedded SQlite database is realized on WinCE6.0 for effectively managing data. The closed loop control is realized by employing fuzzy control algorithm and the test result shows that the deviation of atmospheric temperature is controlled within ± 0.5° C, the deviation of illumination intensity is controlled within ± 283 LUX, the deviation of CO2 concentration is controlled within ± 24 PPM, the deviation of atmospheric humidity is controlled within ± 13% and that of soil water content is controlled within ± 0.9%, thus all parameters fully meet practical requirements of flower greenhouse. 展开更多
关键词 Flower greenhouse ZigBee network SENSOR Embedded controller Fuzzy control Intelligent control.
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Development of the Operating Circuit for a LED Lamp Based on the Cockcroft-Walton Circuit
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作者 Tomohiro Yamaguchi Yuta Nakamura Cixin Wei Yoshio Watanabe 《Journal of Energy and Power Engineering》 2012年第12期1957-1964,共8页
The operating circuits for LED (light emitting diode) lamp composed of diodes and DC capacitors only are proposed. The proposed circuit is based on a double-voltage rectifier circuit and a Cockcroft-Walton circuit. ... The operating circuits for LED (light emitting diode) lamp composed of diodes and DC capacitors only are proposed. The proposed circuit is based on a double-voltage rectifier circuit and a Cockcroft-Walton circuit. The circuit can operate LED without flicker, and is free from switching noise since high frequency switching circuit is not used. To replace an AC capacitor by a DC capacitor for the ballast, a diode is connected across the capacitor in parallel, and the operating voltage of LED unit is kept at the value greater than the peak voltage of the input power source. The circuit realizes high efficiency and high input power factor compared with the operating circuits on the market. Cockcroft-Walton-type circuit can operate many LED devices in series connection. Series connection is preferable for fabricating LED unit of a constant voltage characteristic. Moreover, fairly flat waveform of LED operating current is realized by Cockcrofl-Walton-type circuit, even though capacitor ballast is used. 展开更多
关键词 LED lamp light emitting diode Cockcroft-Walton circuit double-voltage rectifier circuit DC capacitor DC convertor.
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Vibration Analysis and Direct Control of XY Table Automated Assembly Machines
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作者 Charfeddine Mrad 《Journal of Mechanics Engineering and Automation》 2013年第1期7-13,共7页
XY table automated assembly machines ensure time saving and quality improving in the electronics industry. Recently, due to the need of higher operation speeds and lighter machines in PCB (Printed Circuit Board) ass... XY table automated assembly machines ensure time saving and quality improving in the electronics industry. Recently, due to the need of higher operation speeds and lighter machines in PCB (Printed Circuit Board) assembly, a challenging problem has arisen which is the table positioning vibration. The high speed with the machine flexibility, make the positioning vibration inevitable although the inner control. The positioning vibration is to be reduced otherwise the machine becomes useless. Firstly, the machine is modeled, the positioning vibration is formulated, and then analyzed. Secondly, using the analysis, three direct control methods are identified to decrease the positioning vibration, they are based on the kinematics, dynamics, and operation of the machine. Thirdly, the methods are examined numerically to evaluate their efficiency. Lastly, the identified methods are discussed to conclude on their application. The results are a real contribution in the vibration control of XY table automated assembly machines, which is classified as industrial knowhow. 展开更多
关键词 Assembly machines XY table positioningvibration vibration analysis direct control.
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Influence of DFIG Wind Turbine Protection and Control during Voltage Dip on Circuit Breaker Operation
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作者 Anssi Salomo Makinen Ontrei Raipala Sami Repo Heikki Tuusa 《Journal of Energy and Power Engineering》 2013年第1期126-138,共13页
This paper analyzes a DFIG (doubly fed induction generator) WT (wind turbine) fault current after a symmetrical network voltage dip. The goal is to identify the factors determining how fast the first zero crossing... This paper analyzes a DFIG (doubly fed induction generator) WT (wind turbine) fault current after a symmetrical network voltage dip. The goal is to identify the factors determining how fast the first zero crossings of the fault current occur. This is an important subject because the ftmdamental property of the CB (circuit breaker) is that it breaks the current when the current is very near zero. The study was conducted using a hardware-in-the-loop test environment constructed using two real time simulators (dSPACE and RTDS) and a commercial protection relay. It is found that the reactive current injection during a voltage dip demanded by the grid codes enhances the operation of the WT protection because the zero crossings of the currents through CB are attained earlier. In addition, the size of the crowbar resistance has a significant influence on the zero crossings. 展开更多
关键词 DFIG reactive current circuit breaker loss of mains relay protection.
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Characteristic investigation of permanent magnet actuator for vacuum contactors operating with an intrinsically safe low voltage
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作者 FANG ShuHua LIN HeYun +2 位作者 Ho SiuLau WANG XianBing JIN Ping 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第6期1688-1694,共7页
This paper reports a new application of permanent magnet actuator for vacuum contactors.A novel permanent magnet(PM) actuator to drive a vacuum contactor with intrinsically safe and low supply voltage is proposed.PM i... This paper reports a new application of permanent magnet actuator for vacuum contactors.A novel permanent magnet(PM) actuator to drive a vacuum contactor with intrinsically safe and low supply voltage is proposed.PM is mounted on the static iron of the contactor to enhance its holding force and reliability.While only one coil is used to break the vacuum contactor,two series coils are deployed to yield a high magnetomotive force to realize the making operation.The electrical circuit equation,mechanical equation and magnetic field are all coupled in the simulation.A prototype is manufactured and tested to validate and showcase the performance of the contactor which is equipped with the proposed PM actuator. 展开更多
关键词 low voltage control permanent magnet actuator intrinsic safety vacuum contactor
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