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三相异弹模薄板界面裂缝缝端应力奇异性与应力场 被引量:1
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作者 周鸿钧 王广印 周红锤 《郑州工业大学学报》 2000年第3期1-4,共4页
研究了三相异弹模薄板界面裂缝缝端奇异性与几何边界条件和弹性常数的依赖关系 .采用原点设置在缝端的极坐标系统 ,用复势函数方法推导了缝端应力场的表达式 ,求得应力强度因子 .算例表明 ,本文的解答是正确的 。
关键词 应力奇 界面裂缝 复势函数方法 应力强度因子 应力场 三相异弹模薄板
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Y560系列三相异步电动机设计特点 被引量:1
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作者 李贤明 张霄 周慧 《电机技术》 2002年第3期30-31,共2页
介绍了Y560系列50Hz,2、4、6、8、10、12极6kV、10kV系列中型高压三相异步电动机设计的特点。
关键词 Y560系列 三相电动机 设计特点
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三相异步电动机简单控制电路实验常见错误及改进措施
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作者 郭琳 《黑龙江科技信息》 2010年第23期80-80,共1页
针对三相异步电动机定子绕组串电阻降压启动控制电路实验,总结了常见的错误,并提出改进措施。
关键词 三相异电动机 控制电路 错误 改进措施
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具有光电倍增的宽光谱三相体异质结有机彩色探测器
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作者 安涛 涂传宝 龚伟 《物理学报》 SCIE EI CAS CSCD 北大核心 2018年第19期329-337,共9页
实验研究了P3HT:PBDT-TT-F:PCBM三相体异质结活性层光谱拓宽及其材料混合度对探测器光电特性的影响以及陷阱辅助光电倍增的机理.在此基础上,获得了一个覆盖350—750 nm波长范围的彩色探测器.该探测器在-1 V低偏压下红绿蓝三基色的光响... 实验研究了P3HT:PBDT-TT-F:PCBM三相体异质结活性层光谱拓宽及其材料混合度对探测器光电特性的影响以及陷阱辅助光电倍增的机理.在此基础上,获得了一个覆盖350—750 nm波长范围的彩色探测器.该探测器在-1 V低偏压下红绿蓝三基色的光响应度和外量子效率分别达到了470, 381, 450 mA/W和93%,89%, 121%,比探测率均接近10^(12)Jones,且各基色的特性参数最大平均相对偏差均小于20%,同时频率带宽分别达到了5, 8, 8 kHz.结果表明:在保持二相体异质结薄膜原有微观形貌下,掺入少量光谱拓宽材料可实现活性层吸收光谱的拓宽.利用能级陷阱中电子的辅助作用引入外电路空穴注入,可实现探测器光电倍增.通过调节三相材料的混合度可实现基色间探测能力的均衡性. 展开更多
关键词 有机彩色图像传感器 光电探测器 三相质结 光电倍增
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宽光谱高比探测率有机光电探测器 被引量:1
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作者 安涛 龚伟 《光子学报》 EI CAS CSCD 北大核心 2018年第11期160-167,共8页
为实现有机光电探测器对三基色(红、绿、蓝)的全响应以及器件性能的改善,研究了在聚(3-己基噻吩)(P3HT)∶[6,6]-苯基-C61-丁酸甲酯(PC61BM)活性层中,掺入窄带隙材料(4,8-双-(2-乙基己氧基)-苯并[1,2-b:4,5-b′]二噻吩)-(4-氟代噻并[3,4... 为实现有机光电探测器对三基色(红、绿、蓝)的全响应以及器件性能的改善,研究了在聚(3-己基噻吩)(P3HT)∶[6,6]-苯基-C61-丁酸甲酯(PC61BM)活性层中,掺入窄带隙材料(4,8-双-(2-乙基己氧基)-苯并[1,2-b:4,5-b′]二噻吩)-(4-氟代噻并[3,4-b]噻吩)(PBDT-TT-F)实现光谱拓宽以及通过提高阳极修饰层电子注入势垒来降低暗电流,改善探测器性能的方法,研究了PBDT-TT-F掺杂浓度以及修饰层厚度对探测器光电学性能的影响规律.在此基础上,获得了一个覆盖400~750nm波长范围的探测器,并且在低偏压-1V下三基色的线性动态范围和比探测率分别达到了81、80、81dB和2.7×1012、2.0×1012、2.6×1012 Jones.结果表明:在保持原有二相体异质结薄膜的微观形貌和电学特性前提下,掺入13wt.%少量光谱拓宽材料可实现活性层的光谱拓宽.采用合适厚度的三氧化钼(MoO3)层替换原有的聚乙撑二氧噻吩-聚(苯乙烯磺酸盐)(PEDOT∶PSS)阳极修饰层,可使探测器的三基色线性动态范围和比探测率大幅提高.该研究为研发宽光谱高探测率三基色有机光电探测器提供了一种新思路. 展开更多
关键词 有机光电探测器 三相质结 宽光谱 阳极缓冲层 比探测率
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电机节能新突破自适应随动控制技术简介
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作者 张兆龙 《资源与发展》 2010年第1期28-29,共2页
一、自适应随动控制技术填补了恒速运行类设备电机节能的空白电力系统中的主要耗能设备是各种电机。2008年,我国在役的10亿台电机(4KW以上的约2亿台)中.装机6亿KW.能耗占工业用电的70%,占整个电网的60%。因此电机节能是电力节能的重中... 一、自适应随动控制技术填补了恒速运行类设备电机节能的空白电力系统中的主要耗能设备是各种电机。2008年,我国在役的10亿台电机(4KW以上的约2亿台)中.装机6亿KW.能耗占工业用电的70%,占整个电网的60%。因此电机节能是电力节能的重中之重。电机在设计时,选择的额定功率一般是按极限工况计算,再加上一定的富裕量;而实际运行中,绝大多数设备都存在运行功率小于额定功率的情况,造成了各种设备中普遍存在"大马拉小车"的现象。 展开更多
关键词 电机系统 随动控制 运行功率 恒速运行 主要耗能设备 电力节能 工业用电 电机运行 节电效果 三相异
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Electromagnetic Torque Estimation of a Three-Phase Induction Motor for Setting the Feedrate of a Milling Machine
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作者 Elida Fernanda Xavier Julio Simplicio Amaud da Silva +1 位作者 Cicero da Rocha Souto Isaac Soares de Freitas 《Journal of Mechanics Engineering and Automation》 2014年第6期511-520,共10页
In this paper, it presents a project of a fuzzy controller and a neural estimator to control a coordinate table powered by three-phase induction motor, aiming to implement an intelligent milling system. The position/s... In this paper, it presents a project of a fuzzy controller and a neural estimator to control a coordinate table powered by three-phase induction motor, aiming to implement an intelligent milling system. The position/speed control is performed using vector techniques of three-phase induction machines. The estimation of the motor electromagnetic torque is used for setting the feedrate of the table. The speed control is developed using TS (Takagi-Sugeno) fuzzy logic model and electromagnetic torque estimation using neural network type LMS (least mean square) algorithm. The induction motor is powered by a frequency inverter driven by a DSP (digital signal processor). Control strategies are implemented in DSP. Simulation results are presented for evaluating the performance of the system. 展开更多
关键词 MACHINING speed control torque estimation fuzzy logic neural network
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Transient Analysis and Control Strategies for a Quad-lnverter Multiphase Multilevel Motor Drive in Faulty Conditions
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作者 Gabriele Grandi Padmanaban Sanjeevkumar Yasser Gritli 《Journal of Energy and Power Engineering》 2013年第7期1304-1315,共12页
In this paper, post-fault-tolerant control strategies for quad-inverter multiphase-multilevel induction motor drives are investigated. More specifically, four standard two-level three-phase VSIs (voltage source inver... In this paper, post-fault-tolerant control strategies for quad-inverter multiphase-multilevel induction motor drives are investigated. More specifically, four standard two-level three-phase VSIs (voltage source inverters) supplying the open-end windings of a dual three-phase induction motor is considered, quadrupling the power capability of a single VSI with given voltage and current ratings. In healthy conditions, the control algorithm is able to generate multi-level voltage waveforms, equivalent to the ones of a three-level inverter and to share the total motor power among the four dc sources in each switching period. This sharing capability is investigated under post-fault operating conditions, when one VSI must be completely insulated due to a severe failure on it. In this case, the conversion power unit can operate with a reduced power rating by a proper modulation of the remaining three VSIs. The whole ac motor drive has been numerically implemented, and the effectiveness of the proposed control strategies under healthy and post-fault operating conditions have been proved. 展开更多
关键词 Dual three-phase motor multi-level inverter multi-phase motor drive multi-phase fault post-fault-tolerance space vectormodulation.
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Microcontroller-Based Variable Speed Drive for Three-Phase Induction Motor in Cooling Applications
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作者 Kondapalli Siva Rama Rao Lee Teng Hong 《Journal of Energy and Power Engineering》 2012年第4期656-662,共7页
This paper presents an electronic VSD (variable speed drive) for three-phase IM (induction motor) using a microcontroller. The VSD is designed for cooling applications where the 1M is coupled to a cooling fan. The... This paper presents an electronic VSD (variable speed drive) for three-phase IM (induction motor) using a microcontroller. The VSD is designed for cooling applications where the 1M is coupled to a cooling fan. The drive receives temperature feedback from objects to be cooled and output a corresponding frequency to the IM. A prototype of the VSD is constructed to control a 175 W, four pole, squirrel cage three-phase IM. The heart of the control circuit is a low-cost microchip's PICI6F777 microcontroller which is programmed using C language to generate variable frequency SPWM (sinusoidal pulse width modulation) switching signals. These switching signals are fed to an 1GBT inverter. The VSD constructed can be switched between two modes of speed control" automatic temperature-controlled mode and manual user-controlled mode. Cost savings using the prototype are demonstrated. 展开更多
关键词 IGBT inverter PIC microcontroller SPWM three-phase induction motor variable speed drive.
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Investigation of Interline Dynamic Voltage Restorer with Virtual Impedance Injection
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作者 Ahmed Elserougi Ahmed Hossam-Eldin +1 位作者 Ahmed Massoud Shehab Ahmed 《Journal of Energy and Power Engineering》 2012年第1期101-109,共9页
The inter-line dynamic voltage restorer (IDVR) consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for volta... The inter-line dynamic voltage restorer (IDVR) consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for voltage sag that appears in its feeder (voltage control mode), the other inverters pump the required power into the dc bus (power control mode). Each inverter will have both voltage and power controllers; only one controller is in use during the abnormal conditions according to its feeder state. The voltage controller uses one of the dynamic voltage restoration techniques. In this paper, the in-phase technique is applied and two types of loads are considered (constant impedance and three phase induction motor). Since the voltage restoration process may need real power injection into the distribution system, the power controller injects this power via voltage injection. This voltage injection is simulated by voltage drop across series virtual impedance. A new scheme is proposed to select the impedance value. The impedance value is selected such that the power consumed by this impedance represents the required power to be transferred without perturbing the load voltage. The performance of this system is also studied during voltage swell. A scheme for operation of multi-feeder IDVR system is proposed in this paper. Simulation results substantiate the proposed concept. 展开更多
关键词 Dynamic voltage restorers IDVR voltage sag voltage swell power quality.
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Efficiency in Boiler Feed Pumps for Industrial Steam Generation
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作者 Guilherme Filippo Fi|ho 《Journal of Energy and Power Engineering》 2014年第6期1021-1029,共9页
This paper presents some opportunities to improve feedwater system efficiency for industrial boilers, usually consisting of multistage centrifugal pumps driven by three-phase induction motors. There is abundant litera... This paper presents some opportunities to improve feedwater system efficiency for industrial boilers, usually consisting of multistage centrifugal pumps driven by three-phase induction motors. There is abundant literature on the efficiency in steam boilers. However, few deal exclusively with feedwater systems. The total horsepower in boiler feed pumps and the corresponding energy consumption estimated for Brazilian industries are as follows: 110.5 MWE of motor driven power and a yearly electricity consumption of 442 GWh for a population of 7,800 steam boilers, approximately. It is estimated that there can be an efficiency improvement in feedwater systems for industrial boilers of 30% on average. To a large extent, these opportunities reside in older boilers that are very common in the Brazilian industrial sector. The most common causes for the low efficiency of feedwater systems are: the control loop of the feedwater, oversized boilers and excessive operational pressure set. Sometimes, the boiler feedwater system can present more than one problem simultaneously. Any kind of solution involves some speed regulation, new pump and number of pumps. Each problem generation facilities were selected in which common inefficiencies cases, the improvement in efficiency can get to 37%. form of intervention in boiler feed pumps, such as: impeller trim, may have more than one solution. Three distinct industrial steam are present. The suggested solutions were analyzed. In these three 展开更多
关键词 Industrial boiler boiler feed pump industrial energy efficiency.
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Direct on Line Starting Induction Motor with Thyristor Switched Capacitor Based Voltage Regulation
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作者 E.P.da Silveira R.C. Pires A.T.L.de Almeida A.J.J. Rezek 《Journal of Energy and Power Engineering》 2010年第9期49-55,共7页
The purpose of this paper is to show a laboratory scale implementation of a Thyristor Switched Capacitors (TSC) as an alternative for voltage regulation during a direct on line three-phase induction motor starting o... The purpose of this paper is to show a laboratory scale implementation of a Thyristor Switched Capacitors (TSC) as an alternative for voltage regulation during a direct on line three-phase induction motor starting on an emulated weak transmission line. Thyristor switched capacitor bank was chosen because it is a well known topology, considering the very nature of the direct starting induction motors, which represents a highly inductive load, the use of switched reactors becomes unnecessary. Such fact minimizes the introduction of harmonics components, and also reduces the cost of the implementation. The binary disposition of the banks allows a variable Var compensation with sixteen steps, in this case. The solution makes use of low cost devices combined with sliding window voltage and current measurement algorithm and a PI control with dead band control for achieve the shown experimental results, where the system is able to manage a typically 20% voltage drop, reducing it to less than 4%. The schematic of the developed circuit, the control technique and a quite simple method to calculate the binary weight capacitors banks are also presented. 展开更多
关键词 Induction motor thyristor switched capacitor voltage regulation
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IE3 Efficiency Induction Motors with Aluminum and Copper Rotor Cage: Technical and Economic Comparison
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作者 Francesco Parasiliti Marco Villani 《Journal of Energy and Power Engineering》 2014年第5期902-910,共9页
The aim of this study was to design three-phase induction motors with aluminum and copper cage, in the range 0.75 ÷22 kW, to fulfill the 1E3 efficiency level according to typical performance and standard constrai... The aim of this study was to design three-phase induction motors with aluminum and copper cage, in the range 0.75 ÷22 kW, to fulfill the 1E3 efficiency level according to typical performance and standard constraints. The proposed study has concerned TEFC ( totally Enclosed Fan-Cooled ), 400 V, 50 Hz, SI duty three phase squirrel-cage induction motors only. The motors' designs, with AI and Cu cage, have been optimized in order to reach the minimum efficiency level IE3 at lowest active material costs and satisfy the physical and performance constraints of the designs, which are the motor specifications. A suitable optimization procedure has been used which allowed to find the "best design" by chancing the geometric dimensions of the stator, rotor shape, the stator winding and the stack length. In order to guarantee the goodness and feasibility of the optimized designs, several constrains have been imposed. 展开更多
关键词 Induction motors EFFICIENCY copper rotor design optimization.
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Establishment of an arsenic-resistant human gallbladder carcinoma cell line and analysis of the differential expressions of genes associated with apoptosis 被引量:1
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作者 Dalong Wu Xiaowei He Chengwen Zhang 《The Chinese-German Journal of Clinical Oncology》 CAS 2010年第2期86-88,共3页
Objective: The aim of the study was to establish an arsenic trioxide (ATO)-resistant cell line of human gallbladder carcinoma, GBC-SD/ATO, and to analyze the differential expressions of its apoptosis-associated gen... Objective: The aim of the study was to establish an arsenic trioxide (ATO)-resistant cell line of human gallbladder carcinoma, GBC-SD/ATO, and to analyze the differential expressions of its apoptosis-associated genes, so as to investigate a correlation between ATO induced resistance of gallbladder carcinoma and expressions of apoptosis associated genes. Methods: The resistant cell line was obtained in vitro by culture of human gallbladder carcinoma cell line GBC-SD with increasingly stepwise concentrations of ATO. The sensitivities of GBC-SD cells and GBC-SD/ATO cells to ATO were determined by MTT assay respectively, cDNA microarray containing 458 apoptosis-related human genes was used to compare the gene expression profiles of GBC-SD/ATO cells and corresponding sensitive cell line GBC-SD. Results: GBC-SD/ATO cell line was established successfully after 8 months of exposure to increasing concentrations of ATO. Compared with the parental cell line, GBC-SD/ATO was 13.6 times more resistant to ATO. Of the 458 apoptosis-related genes, 17 genes were detected having 〉 2-fold difference of expression between the GBC-SD/ATO and GBC-SD cells, with 6 genes up-regulated and 11 genes down-regulated in GBC-SD/ATO cells. Conclusion: The 17 genes invoJved in the apoptosis pathway might be relevant to the resistance of GBC-SD/ATO cells to ATO, suggesting that the modulation of expression of apoptosis-related genes may be a main mechanism of acquired resistance in GBC-SD/ATO. 展开更多
关键词 gallbladder carcinoma RESISTANCE APOPTOSIS arsenic trioxide (ATO)
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Control of Doubly Fed Induction Generator under Unbalanced Voltages for Reduction of Torque Pulsation
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作者 S. Wangsathitwong S. Sirisumrannukul +1 位作者 S. Chatratana W. Deleroi 《Journal of Energy and Power Engineering》 2011年第3期243-251,共9页
The unbalanced voltages cause negative effects on the doubly fed induction generator (DFIG) sucn as torque pulsation,and increased stator current. Based on the symmetrical component theory, the torque pulsation is t... The unbalanced voltages cause negative effects on the doubly fed induction generator (DFIG) sucn as torque pulsation,and increased stator current. Based on the symmetrical component theory, the torque pulsation is the consequence of the interaction of stator and rotor currents of different sequences. This paper presents a control technique to reduce the effect of unbalanced voltages on the DFIG in wind energy conversion systems. The negative sequence stator voltage is derived from the unbalanced three phase stator voltages. The compensated rotor voltage in terms of the derived negative sequence stator voltage and slip which minimizes the negative stator and rotor currents is proposed. The results from the simulation of control system with steady state model and dynamic model of the DFIG show that additional control loop with compensated voltage can significantly reduce torque and reactive power pulsations. 展开更多
关键词 Doubly fed induction generator (DFIG) unbalanced voltages symmetrical components.
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