Based on the equivalent circuit model of a two-port optical receiver front-end,the relationship between the equivalent input noise current spectral density and the noise figure is analyzed. The derived relationship ha...Based on the equivalent circuit model of a two-port optical receiver front-end,the relationship between the equivalent input noise current spectral density and the noise figure is analyzed. The derived relationship has universal validity for determining the equivalent input noise current spectral density for optical receiver designs, as verified by measuring a 155Mb/s high-impedance optical receiver front.end. Good agreement between calculated and simulated results has been achieved.展开更多
The high corrosion resistance of duplex stainless steel （DSS） is due to elements such as Cr, Mo and N, hut also depends on the microstructure. The best general properties are obtained with approximately equal amount...The high corrosion resistance of duplex stainless steel （DSS） is due to elements such as Cr, Mo and N, hut also depends on the microstructure. The best general properties are obtained with approximately equal amounts of austenite and ferrite and the absence of third phases such as σ（sigma） and Cr2N. In the present work the effect of heat input variations on the microstructure and corrosion resistance of a DSS UNS S32760 in artificial sea water media were studied. The corrosion resistance in 3.5 % of NaCl solution was evaluated by potentiostatic polarization tests at room temperature. It is found that the presence of sigma phase and Cr2N decreases the corrosion potential. The specimen with heat input of approximately 0.95 kJ/mm have the best corrosion characteristics, which is the result for the lack of deleterious phases such as sigma and Cr2 N and balanced ferrite austenite proportion.展开更多
In this paper, by change of integration path in complex spectrum domain and by defining input admittance as the ratio of complex radiated power to amplitude of square of voltage across the gap, new expressions of admi...In this paper, by change of integration path in complex spectrum domain and by defining input admittance as the ratio of complex radiated power to amplitude of square of voltage across the gap, new expressions of admittance (valid for all frequencies ) of infinitely long cylindrical antenna with and without conducting ground are obtained. Meanwhile corresponding formulas of current distribution are derived in detail. Some numerical computations are also given.展开更多
Based on the data and method offered by Liu et al. （2009）, the direct wind and Stokes drift-induced energy inputs into the Ekman layer within the Antarctic Circumpolar Current （ACC） area are reestimated since the ...Based on the data and method offered by Liu et al. （2009）, the direct wind and Stokes drift-induced energy inputs into the Ekman layer within the Antarctic Circumpolar Current （ACC） area are reestimated since the results of the former have been proved to be underestimated. And the result shows that the total rate of energy input into the Ekman-Stokes layer within the ACC area is 852.41 GW, including 649.75 GW of direct wind energy input （76%） and 202.66 GW of Stoke drift-induced energy input （24%）. Total increased energy input, due to wave-induced Coriolis-Stokes forcing added to the classical Ekman model, is 52.05 GW, accounting for 6.5% of the wind energy input into the classical Ekman layer. The long-term variability of direct wind and Stokes drift-induced energy inputs into the Ekman layer within the ACC is also investigated, and the result shows that the Stokes drift hinders the decadal increasing trend of direct wind energy input. Meanwhile, there is a period of 4-5 a in the energy spectrums, as same as the Antarctic circumpolar wave.展开更多
为使对换流阀工作状态的控制更加精确、抑制换相失败,提出了一种基于多分支多输入多输出(Multiple input multiple output,MIMO)深度学习的高压直流输电(Line commutated converter high voltage direct current,LCC-HVDC)换流器阀电流...为使对换流阀工作状态的控制更加精确、抑制换相失败,提出了一种基于多分支多输入多输出(Multiple input multiple output,MIMO)深度学习的高压直流输电(Line commutated converter high voltage direct current,LCC-HVDC)换流器阀电流波形反演方案。对现行实际工程中常用的基于差流换相失败的检测方案进行仿真分析,发现检测结果存在滞后性。阀电流波形的反演模型,其输入特征量为三相交流电流、输出量为6个阀电流,属于MIMO的场景。为提取更多特征信息,基于Inception-ResNet结构、采用多种不同尺寸的卷积,设计多分支MIMO深度学习的换流器阀电流反演模型,并以三相电流作为模型输入,6个阀电流作为输出量,对多分支MIMO模型进行训练。最后,对阀电流的波形进行预测反演。仿真结果表明,多分支MIMO模型对阀电流波形的反演具有较好的适用性,反演结果的相关系数在0.9836以上、平均绝对误差在0.1284以下、且均方误差在0.0286以内,误差变化程度较低。展开更多
The concept of connecting two boost half bridge DC-DC converter modules in input-paral- lel output-parallel configuration is presented. The input-parallel-output-parallel （IPOP） converter consists of multiple boost ...The concept of connecting two boost half bridge DC-DC converter modules in input-paral- lel output-parallel configuration is presented. The input-parallel-output-parallel （IPOP） converter consists of multiple boost half bridge （BHB） DC-DC converter modules which are connected in par- allel at the input and output side. This kind of converter is an attractive solution for high power ap- plications. The correlation between input current sharing （ICS） and output current sharing （OCS） of the IPOP converter basic modules is described. Two loop control strategies, consisting of input cur- rent loop and output voltage loop, have been developed to achieve equal ICS and OCS in this present work. The control strategy for the IPOP configuration of boost haft bridge DC-DC converter has been verified for different load conditions （half load and full load）, The IPOP system proposed here is comprising of two modules but it can be extended to three or more. The performance of the pro- posed system along with the control strategy is verified by simulation in MATLAB using Simpower tool. Finally the satisfactory simulation results are obtained.展开更多
This paper presents an efficient supply current wave shaping technique for bridgeless interleaved Single Ended Primary Inductor Converter(SEPIC).The SEPIC converter converts an Alternating Current(AC)to Direct Current...This paper presents an efficient supply current wave shaping technique for bridgeless interleaved Single Ended Primary Inductor Converter(SEPIC).The SEPIC converter converts an Alternating Current(AC)to Direct Current(DC)with the boost converter.Power Factor Correction(PFC)is progressively significant to achieve high energy efficiency.The overall system efficiency can be increased as the bridgeless topology has less conduction losses from rectifying bridges.Also,the bridgeless and interleaved techniques are incorporated in this study to achieve better performance.The performance of the system is analyzed on both current control and sensor-less techniques.Different controllers such as Proportional Integral(PI)control,peak current control,Non-Linear Carrier(NLC)control,and sensor-less current control are integrated.All the above controllers are implemented using MATrix LABoratory(MATLAB)/SIMULINK.The performance parameter,namely Power Factor(PF),Total Harmonic Distortion(THD),is computed for both open loop and closed loop condition.The sensor-less current control method is implemented using the DsPIC30F2010 controller.The circuit performance is also verified from the simulation and hardware results.The proposed controller has inbuilt Analog-to-Digital Converter(ADC),Digital-to-Analog Converter(DAC),Pulse Width Modulation(PWM)generator,and provides fast responses.展开更多
文摘Based on the equivalent circuit model of a two-port optical receiver front-end,the relationship between the equivalent input noise current spectral density and the noise figure is analyzed. The derived relationship has universal validity for determining the equivalent input noise current spectral density for optical receiver designs, as verified by measuring a 155Mb/s high-impedance optical receiver front.end. Good agreement between calculated and simulated results has been achieved.
文摘The high corrosion resistance of duplex stainless steel （DSS） is due to elements such as Cr, Mo and N, hut also depends on the microstructure. The best general properties are obtained with approximately equal amounts of austenite and ferrite and the absence of third phases such as σ（sigma） and Cr2N. In the present work the effect of heat input variations on the microstructure and corrosion resistance of a DSS UNS S32760 in artificial sea water media were studied. The corrosion resistance in 3.5 % of NaCl solution was evaluated by potentiostatic polarization tests at room temperature. It is found that the presence of sigma phase and Cr2N decreases the corrosion potential. The specimen with heat input of approximately 0.95 kJ/mm have the best corrosion characteristics, which is the result for the lack of deleterious phases such as sigma and Cr2 N and balanced ferrite austenite proportion.
文摘In this paper, by change of integration path in complex spectrum domain and by defining input admittance as the ratio of complex radiated power to amplitude of square of voltage across the gap, new expressions of admittance (valid for all frequencies ) of infinitely long cylindrical antenna with and without conducting ground are obtained. Meanwhile corresponding formulas of current distribution are derived in detail. Some numerical computations are also given.
基金The National Natural Science Foundation of China under contract Nos 40930844 and 40976005
文摘Based on the data and method offered by Liu et al. （2009）, the direct wind and Stokes drift-induced energy inputs into the Ekman layer within the Antarctic Circumpolar Current （ACC） area are reestimated since the results of the former have been proved to be underestimated. And the result shows that the total rate of energy input into the Ekman-Stokes layer within the ACC area is 852.41 GW, including 649.75 GW of direct wind energy input （76%） and 202.66 GW of Stoke drift-induced energy input （24%）. Total increased energy input, due to wave-induced Coriolis-Stokes forcing added to the classical Ekman model, is 52.05 GW, accounting for 6.5% of the wind energy input into the classical Ekman layer. The long-term variability of direct wind and Stokes drift-induced energy inputs into the Ekman layer within the ACC is also investigated, and the result shows that the Stokes drift hinders the decadal increasing trend of direct wind energy input. Meanwhile, there is a period of 4-5 a in the energy spectrums, as same as the Antarctic circumpolar wave.
文摘为使对换流阀工作状态的控制更加精确、抑制换相失败,提出了一种基于多分支多输入多输出(Multiple input multiple output,MIMO)深度学习的高压直流输电(Line commutated converter high voltage direct current,LCC-HVDC)换流器阀电流波形反演方案。对现行实际工程中常用的基于差流换相失败的检测方案进行仿真分析,发现检测结果存在滞后性。阀电流波形的反演模型,其输入特征量为三相交流电流、输出量为6个阀电流,属于MIMO的场景。为提取更多特征信息,基于Inception-ResNet结构、采用多种不同尺寸的卷积,设计多分支MIMO深度学习的换流器阀电流反演模型,并以三相电流作为模型输入,6个阀电流作为输出量,对多分支MIMO模型进行训练。最后,对阀电流的波形进行预测反演。仿真结果表明,多分支MIMO模型对阀电流波形的反演具有较好的适用性,反演结果的相关系数在0.9836以上、平均绝对误差在0.1284以下、且均方误差在0.0286以内,误差变化程度较低。
文摘The concept of connecting two boost half bridge DC-DC converter modules in input-paral- lel output-parallel configuration is presented. The input-parallel-output-parallel （IPOP） converter consists of multiple boost half bridge （BHB） DC-DC converter modules which are connected in par- allel at the input and output side. This kind of converter is an attractive solution for high power ap- plications. The correlation between input current sharing （ICS） and output current sharing （OCS） of the IPOP converter basic modules is described. Two loop control strategies, consisting of input cur- rent loop and output voltage loop, have been developed to achieve equal ICS and OCS in this present work. The control strategy for the IPOP configuration of boost haft bridge DC-DC converter has been verified for different load conditions （half load and full load）, The IPOP system proposed here is comprising of two modules but it can be extended to three or more. The performance of the pro- posed system along with the control strategy is verified by simulation in MATLAB using Simpower tool. Finally the satisfactory simulation results are obtained.
文摘This paper presents an efficient supply current wave shaping technique for bridgeless interleaved Single Ended Primary Inductor Converter(SEPIC).The SEPIC converter converts an Alternating Current(AC)to Direct Current(DC)with the boost converter.Power Factor Correction(PFC)is progressively significant to achieve high energy efficiency.The overall system efficiency can be increased as the bridgeless topology has less conduction losses from rectifying bridges.Also,the bridgeless and interleaved techniques are incorporated in this study to achieve better performance.The performance of the system is analyzed on both current control and sensor-less techniques.Different controllers such as Proportional Integral(PI)control,peak current control,Non-Linear Carrier(NLC)control,and sensor-less current control are integrated.All the above controllers are implemented using MATrix LABoratory(MATLAB)/SIMULINK.The performance parameter,namely Power Factor(PF),Total Harmonic Distortion(THD),is computed for both open loop and closed loop condition.The sensor-less current control method is implemented using the DsPIC30F2010 controller.The circuit performance is also verified from the simulation and hardware results.The proposed controller has inbuilt Analog-to-Digital Converter(ADC),Digital-to-Analog Converter(DAC),Pulse Width Modulation(PWM)generator,and provides fast responses.
