To satisfy the design requirements of analog-to-digital converter （ADC） of high speed sampling system in an infrared focal plane array tester with 1024 × 1024 pixels, a first inter-stage amplifier of 12-bit 40-...To satisfy the design requirements of analog-to-digital converter （ADC） of high speed sampling system in an infrared focal plane array tester with 1024 × 1024 pixels, a first inter-stage amplifier of 12-bit 40- Msample/s pipelined ADC was designed with 0. 35 μm CMOS technology. On the basis of traditional two-stage amplifier, the cross-coupled class AB output stage and cascode compensation were adopted to improve the output vohage swing and bandwidth. Power dissipation was optimized with math tools. Circuit and layout design were completed. Simulation results show that the designed amplifier has good performance of 95 dB dc gain, ±2 V output voltage swing, 190 MHz bandwidth and 63° phase margin with feedback factor 1/4, 33 mW power dissipation and so on, which can meet the system requirements.展开更多
The full bridge zero voltage zero current switching （ FB-ZVZCS ） , which could adjust the output power by keeping the duty ratio of lagging leg constant and changing the duty ratio of leading leg, was a common circu...The full bridge zero voltage zero current switching （ FB-ZVZCS ） , which could adjust the output power by keeping the duty ratio of lagging leg constant and changing the duty ratio of leading leg, was a common circuit of soft switching arc welding inverter power source. However, when the duty ratio of leading leg was reduced to zero, the output power stayed the constant value instead of becoming zero. The working status and waveforms of some major parameters were studied in this paper while the duty ratio of leading leg was zero. It was concluded that the minimum output power of soft switching inverter was related to the charging voltage of paraUel capacitors, and the output power also could be reduced by reducing the duty ratio of lagging leg. A novel two-stage continuous PWM control method that could switch working-mode between full bridge and half bridge was put forward in this paper. This kind of control method could further reduce the output power of soft switching inverter in order to meet the requirement of low heat input of sheet metal welding.展开更多
In this study, we apply the data envelopment analysis(DEA) model to quantitatively measure the input and output efficiency of 19 urban agglomerations in China from 2011 to 2016. The results show that the input and out...In this study, we apply the data envelopment analysis(DEA) model to quantitatively measure the input and output efficiency of 19 urban agglomerations in China from 2011 to 2016. The results show that the input and output efficiency of urban agglomerations is relatively not high, only a small number of that reach the optimal DEA efficiency. It is clearly revealed that there are the regions from the east that presents the better performance, followed by regions from the central and the west. The peer counts show that Zhusanjiao is taken into account 12 times which shows the importance here of the Zhusanjiao model.Considering the values for radial movements and the slack movements, respective urban agglomeration has their improving orientation towards the capital slack, the labor slack or the land slack. It offers a scientific decision-making of for healthy urbanization and high quality development.展开更多
In this paper, we present a theoretical analysis of the output signal-to-interference-plus-noise ratio (SINR) for eigen-space beamformers so as to investigate the performance degradation caused by large pointing error...In this paper, we present a theoretical analysis of the output signal-to-interference-plus-noise ratio (SINR) for eigen-space beamformers so as to investigate the performance degradation caused by large pointing errors. For the sake of reducing such performance loss, a robust scheme, which consists of two cascaded signal processors, is proposed for adaptive beamformers. In the first stage, an algorithm possessing time efficiency is developed to adjust the direc-tion-of-arrival (DOA) estimate of the desired source. Based the achieved DOA estimate, the second stage provides an eigenspace beamformer combined with the spatial derivative constraints (SDC) to further mitigate the cancellation of the desired signal. Analysis and numerical results have been conducted to verify that the proposed scheme yields a better robustness against pointing errors than the conventional approaches.展开更多
虚拟同步发电机固态变压器(Virtual Synchronous Generator-Solid State Transformer,VSG-SST)具有高低压交直流端口,可有效改善电网电压/频率调节能力,提高分布式电源的接入适应性。然而低压配电网电压暂降易导致VSG-SST输出级并网电...虚拟同步发电机固态变压器(Virtual Synchronous Generator-Solid State Transformer,VSG-SST)具有高低压交直流端口,可有效改善电网电压/频率调节能力,提高分布式电源的接入适应性。然而低压配电网电压暂降易导致VSG-SST输出级并网电流超限及不对称,且故障过程中难以提供无功支撑,不具备低电压穿越能力。针对上述问题,文中提出改进VSG控制策略。通过分析传统低电压穿越控制与VSG控制存在的问题,设计VSG电流平衡控制模式来消除电压不对称暂降下产生的负序分量。结合低电压穿越数学模型设计了适用于VSG的低电压穿越控制模式。通过计算有功/无功电流和功率参考值保持输出信号与跟踪量一致,实现两种控制模式间的切换。仿真实验验证了所提控制策略可保障SST在不同电压暂降下完成穿越。展开更多
文摘To satisfy the design requirements of analog-to-digital converter （ADC） of high speed sampling system in an infrared focal plane array tester with 1024 × 1024 pixels, a first inter-stage amplifier of 12-bit 40- Msample/s pipelined ADC was designed with 0. 35 μm CMOS technology. On the basis of traditional two-stage amplifier, the cross-coupled class AB output stage and cascode compensation were adopted to improve the output vohage swing and bandwidth. Power dissipation was optimized with math tools. Circuit and layout design were completed. Simulation results show that the designed amplifier has good performance of 95 dB dc gain, ±2 V output voltage swing, 190 MHz bandwidth and 63° phase margin with feedback factor 1/4, 33 mW power dissipation and so on, which can meet the system requirements.
文摘The full bridge zero voltage zero current switching （ FB-ZVZCS ） , which could adjust the output power by keeping the duty ratio of lagging leg constant and changing the duty ratio of leading leg, was a common circuit of soft switching arc welding inverter power source. However, when the duty ratio of leading leg was reduced to zero, the output power stayed the constant value instead of becoming zero. The working status and waveforms of some major parameters were studied in this paper while the duty ratio of leading leg was zero. It was concluded that the minimum output power of soft switching inverter was related to the charging voltage of paraUel capacitors, and the output power also could be reduced by reducing the duty ratio of lagging leg. A novel two-stage continuous PWM control method that could switch working-mode between full bridge and half bridge was put forward in this paper. This kind of control method could further reduce the output power of soft switching inverter in order to meet the requirement of low heat input of sheet metal welding.
文摘In this study, we apply the data envelopment analysis(DEA) model to quantitatively measure the input and output efficiency of 19 urban agglomerations in China from 2011 to 2016. The results show that the input and output efficiency of urban agglomerations is relatively not high, only a small number of that reach the optimal DEA efficiency. It is clearly revealed that there are the regions from the east that presents the better performance, followed by regions from the central and the west. The peer counts show that Zhusanjiao is taken into account 12 times which shows the importance here of the Zhusanjiao model.Considering the values for radial movements and the slack movements, respective urban agglomeration has their improving orientation towards the capital slack, the labor slack or the land slack. It offers a scientific decision-making of for healthy urbanization and high quality development.
文摘In this paper, we present a theoretical analysis of the output signal-to-interference-plus-noise ratio (SINR) for eigen-space beamformers so as to investigate the performance degradation caused by large pointing errors. For the sake of reducing such performance loss, a robust scheme, which consists of two cascaded signal processors, is proposed for adaptive beamformers. In the first stage, an algorithm possessing time efficiency is developed to adjust the direc-tion-of-arrival (DOA) estimate of the desired source. Based the achieved DOA estimate, the second stage provides an eigenspace beamformer combined with the spatial derivative constraints (SDC) to further mitigate the cancellation of the desired signal. Analysis and numerical results have been conducted to verify that the proposed scheme yields a better robustness against pointing errors than the conventional approaches.
文摘虚拟同步发电机固态变压器(Virtual Synchronous Generator-Solid State Transformer,VSG-SST)具有高低压交直流端口,可有效改善电网电压/频率调节能力,提高分布式电源的接入适应性。然而低压配电网电压暂降易导致VSG-SST输出级并网电流超限及不对称,且故障过程中难以提供无功支撑,不具备低电压穿越能力。针对上述问题,文中提出改进VSG控制策略。通过分析传统低电压穿越控制与VSG控制存在的问题,设计VSG电流平衡控制模式来消除电压不对称暂降下产生的负序分量。结合低电压穿越数学模型设计了适用于VSG的低电压穿越控制模式。通过计算有功/无功电流和功率参考值保持输出信号与跟踪量一致,实现两种控制模式间的切换。仿真实验验证了所提控制策略可保障SST在不同电压暂降下完成穿越。
基金国家"九七三"重点基础研究发展规划项目基金(2006CB303005)国家自然科学基金(60903016+4 种基金6053311060773063)新世纪优秀人才支持计划(NCET-05-0333)黑龙江省教育厅科学技术研究项目(11531276)NSFC-RGC of China(60831160525)资助~~
