Full bridge Zero Voltage Switch PWM converter combines advantages of the PWM control technique and resonant technique. However, Full ZVS is achieved only under large load current because resonant tank of this circu...Full bridge Zero Voltage Switch PWM converter combines advantages of the PWM control technique and resonant technique. However, Full ZVS is achieved only under large load current because resonant tank of this circuit is made up of the parasitic capacitance of the power semiconductors and the leakage inductor of the transformer primary. In this paper two saturable inductors as magnetic switches are added to secondary, so output inductor is always reflected to primary and assists resonant transition. Full ZVS is achieved under lower load current. The above mentioned investigated results are validated by the computerized simulation and hardware circuit experiment.展开更多
Quasi Z-source converter is a single stage soft switched power converter derived from Z-source converter topology, employing an impedance network coupling the source with the converter. The quasi Z-source source conve...Quasi Z-source converter is a single stage soft switched power converter derived from Z-source converter topology, employing an impedance network coupling the source with the converter. The quasi Z-source source converter can buck or boost the voltage and current flow is bidirectional. The duty cycle of the switch can be adjusted to maintain constant voltage during load change. To obtain constant output voltage, proper controller design is a must. This paper presents closed loop control of quasi Z-source converter using PI controller where controller parameters are estimated using the small signal model of the entire system. The transfer function of the system with AC sweep is used to obtain appropriate proportional and integral gain constants to reduce transient dynamics and to reduce steady state error.展开更多
A laser-produced plasma(LPP) source was built using liquid as target and a Nd:YAG laser as the irradiation laser, and the LPP source's radiation with ethanol and acetone target respectively was measured by an AXUV...A laser-produced plasma(LPP) source was built using liquid as target and a Nd:YAG laser as the irradiation laser, and the LPP source's radiation with ethanol and acetone target respectively was measured by an AXUV100 silicon photodiode combined with a McPHERSON model 247 grazing incidence monochromator of the resolution Δλ≤0.075 nm and the wavelength scanning interval 0.5 nm. Both ethanol and acetone target LPP source had EUV emission at 11～20 nm wavelength. The comparison between the spectra of the two kinds of target materials shows that all the two kinds of target source's spectra are the result of oxygen ions' transitions under current source's parameters, but the spectrum intensity from different target sources is different. The spectra intensity from the ethanol target is higher than that from the acetone target. In addition, the target liquid is forced into the vacuum chamber by the background pressure supported by the connected external high pressure gas, and the influence of the background pressure on the source's intensity is investigated.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
With the emergence of the Cultural School in the 1990s, researchers began to deem that translation is inevitably associated with political tendencies and aspirations of social groups, and the relationship between sour...With the emergence of the Cultural School in the 1990s, researchers began to deem that translation is inevitably associated with political tendencies and aspirations of social groups, and the relationship between source language and target language has never gone beyond politics and are always entangled with power. From political perspective, this thesis will take the popularity of Yu Hua’s works in US into account to analyze and explore how cultural soft power, has impacts on translation activities, especially translation direction and source text selection.展开更多
High brightness γ-rays produced by laser Compton scattering(LCS) are ideal probes for the study of nucleon and nuclear structure. We propose such a γ-ray source using the backscattering of a laser from the bright el...High brightness γ-rays produced by laser Compton scattering(LCS) are ideal probes for the study of nucleon and nuclear structure. We propose such a γ-ray source using the backscattering of a laser from the bright electron beam produced by the linac of the Shanghai Soft X-ray Free-electron Laser(SXFEL) test facility at the Shanghai Institute of Applied Physics(SINAP). The performance is optimized through theoretical analysis and benchmarked with 4D Monte-Carlo simulations. The peak brightness of the source is expected to be larger than2 × 1022photons/(mm2mrad2s 0.1%BW) and photon energy ranges from 3.7 Me V to 38.9 Me V. Its performance, compared to Extreme Light Infrastructure-Nuclear Physics(ELI-NP), and the Shanghai Laser-Electron Gamma-ray Source(SLEGS), is given. The potential for basic and applied research is also briefly outlined.展开更多
在影视配乐创作中,乐器数字接口(Musical Instrument Digital Interface,MIDI)采样器及软音源的应用越来越受到重视。这些工具可以模拟各种乐器的声音,拓展了作曲家的创作思路和想象力,同时提高了音乐的质量和效率。详细介绍MIDI采样器...在影视配乐创作中,乐器数字接口(Musical Instrument Digital Interface,MIDI)采样器及软音源的应用越来越受到重视。这些工具可以模拟各种乐器的声音,拓展了作曲家的创作思路和想象力,同时提高了音乐的质量和效率。详细介绍MIDI采样器及软音源的原理和特点,列举相关的主要软件和硬件设备;结合实际案例,详细阐述MIDI采样器及软音源在影视配乐中的实际应用方法和技巧;分析MIDI采样器及软音源在影视配乐中的效果,并针对存在的问题提出相应的建议和改进方案。展开更多
文摘Full bridge Zero Voltage Switch PWM converter combines advantages of the PWM control technique and resonant technique. However, Full ZVS is achieved only under large load current because resonant tank of this circuit is made up of the parasitic capacitance of the power semiconductors and the leakage inductor of the transformer primary. In this paper two saturable inductors as magnetic switches are added to secondary, so output inductor is always reflected to primary and assists resonant transition. Full ZVS is achieved under lower load current. The above mentioned investigated results are validated by the computerized simulation and hardware circuit experiment.
文摘Quasi Z-source converter is a single stage soft switched power converter derived from Z-source converter topology, employing an impedance network coupling the source with the converter. The quasi Z-source source converter can buck or boost the voltage and current flow is bidirectional. The duty cycle of the switch can be adjusted to maintain constant voltage during load change. To obtain constant output voltage, proper controller design is a must. This paper presents closed loop control of quasi Z-source converter using PI controller where controller parameters are estimated using the small signal model of the entire system. The transfer function of the system with AC sweep is used to obtain appropriate proportional and integral gain constants to reduce transient dynamics and to reduce steady state error.
文摘A laser-produced plasma(LPP) source was built using liquid as target and a Nd:YAG laser as the irradiation laser, and the LPP source's radiation with ethanol and acetone target respectively was measured by an AXUV100 silicon photodiode combined with a McPHERSON model 247 grazing incidence monochromator of the resolution Δλ≤0.075 nm and the wavelength scanning interval 0.5 nm. Both ethanol and acetone target LPP source had EUV emission at 11～20 nm wavelength. The comparison between the spectra of the two kinds of target materials shows that all the two kinds of target source's spectra are the result of oxygen ions' transitions under current source's parameters, but the spectrum intensity from different target sources is different. The spectra intensity from the ethanol target is higher than that from the acetone target. In addition, the target liquid is forced into the vacuum chamber by the background pressure supported by the connected external high pressure gas, and the influence of the background pressure on the source's intensity is investigated.
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With the emergence of the Cultural School in the 1990s, researchers began to deem that translation is inevitably associated with political tendencies and aspirations of social groups, and the relationship between source language and target language has never gone beyond politics and are always entangled with power. From political perspective, this thesis will take the popularity of Yu Hua’s works in US into account to analyze and explore how cultural soft power, has impacts on translation activities, especially translation direction and source text selection.
基金Supported by the Major State Basic Research Development Program of China(No.2011CB808300)the Shanghai Natural Science Foundation(No.13ZR1464700)the Knowledge Innovation Project of the Chinese Academy of Sciences(No.255015061)
文摘High brightness γ-rays produced by laser Compton scattering(LCS) are ideal probes for the study of nucleon and nuclear structure. We propose such a γ-ray source using the backscattering of a laser from the bright electron beam produced by the linac of the Shanghai Soft X-ray Free-electron Laser(SXFEL) test facility at the Shanghai Institute of Applied Physics(SINAP). The performance is optimized through theoretical analysis and benchmarked with 4D Monte-Carlo simulations. The peak brightness of the source is expected to be larger than2 × 1022photons/(mm2mrad2s 0.1%BW) and photon energy ranges from 3.7 Me V to 38.9 Me V. Its performance, compared to Extreme Light Infrastructure-Nuclear Physics(ELI-NP), and the Shanghai Laser-Electron Gamma-ray Source(SLEGS), is given. The potential for basic and applied research is also briefly outlined.
文摘在影视配乐创作中,乐器数字接口(Musical Instrument Digital Interface,MIDI)采样器及软音源的应用越来越受到重视。这些工具可以模拟各种乐器的声音,拓展了作曲家的创作思路和想象力,同时提高了音乐的质量和效率。详细介绍MIDI采样器及软音源的原理和特点,列举相关的主要软件和硬件设备;结合实际案例,详细阐述MIDI采样器及软音源在影视配乐中的实际应用方法和技巧;分析MIDI采样器及软音源在影视配乐中的效果,并针对存在的问题提出相应的建议和改进方案。
