Current-voltage （I-V） characteristics of a non-transferred DC arc plasma spray torch operated in argon at vacuum are reported. The arc voltage is of negative characteristics for a current below 200 A, fiat for a cur...Current-voltage （I-V） characteristics of a non-transferred DC arc plasma spray torch operated in argon at vacuum are reported. The arc voltage is of negative characteristics for a current below 200 A, fiat for a current between 200 A to 250 A and positive for a current beyond 250 A. The voltage increases slowly with the increase in carrier gas of arc. The rate of change in voltage with currents is about 3-4 V/100 A at a gas flow rate of about 1-1.5 V/10 standard liter per minute （slpm）. The I-V characteristics of the DC plasma torch are of a shape of hyperbola. Arc power increases with the argon flow rate. and the thermal efficiency of the torch acts in a similar way. The thermal efficiency of the non-transferred DC plasmatron is about 65-78%.展开更多
This research investigates the influence of indoor and outdoor factors on photovoltaic(PV)power generation at Utrecht University to accurately predict PV system performance by identifying critical impact factors and i...This research investigates the influence of indoor and outdoor factors on photovoltaic(PV)power generation at Utrecht University to accurately predict PV system performance by identifying critical impact factors and improving renewable energy efficiency.To predict plant efficiency,nineteen variables are analyzed,consisting of nine indoor photovoltaic panel characteristics(Open Circuit Voltage(Voc),Short Circuit Current(Isc),Maximum Power(Pmpp),Maximum Voltage(Umpp),Maximum Current(Impp),Filling Factor(FF),Parallel Resistance(Rp),Series Resistance(Rs),Module Temperature)and ten environmental factors(Air Temperature,Air Humidity,Dew Point,Air Pressure,Irradiation,Irradiation Propagation,Wind Speed,Wind Speed Propagation,Wind Direction,Wind Direction Propagation).This study provides a new perspective not previously addressed in the literature.In this study,different machine learning methods such as Multilayer Perceptron(MLP),Multivariate Adaptive Regression Spline(MARS),Multiple Linear Regression(MLR),and Random Forest(RF)models are used to predict power values using data from installed PVpanels.Panel values obtained under real field conditions were used to train the models,and the results were compared.The Multilayer Perceptron(MLP)model was achieved with the highest classification accuracy of 0.990%.The machine learning models used for solar energy forecasting show high performance and produce results close to actual values.Models like Multi-Layer Perceptron(MLP)and Random Forest(RF)can be used in diverse locations based on load demand.展开更多
传统桥式全波RF-DC变换电路在设计过程中忽略了二极管导通损耗,从而影响系统效率。采用了E类零电压开关(Zero Voltage Switching,ZVS)RF-DC变换电路,设计了谐振频率为8 MHz,输入功率为1.21 W的无线电力传输系统接收模块。并利用multisi...传统桥式全波RF-DC变换电路在设计过程中忽略了二极管导通损耗,从而影响系统效率。采用了E类零电压开关(Zero Voltage Switching,ZVS)RF-DC变换电路,设计了谐振频率为8 MHz,输入功率为1.21 W的无线电力传输系统接收模块。并利用multisim软件进行了仿真。结果表明,该设计方法降低了二极管导通损耗,有效避免了传统桥式全波RF-DC变换电路存在的缺陷,效率可达92%。展开更多
单级式双有源桥(dual active bridge,DAB)DC/AC变换器控制自由度多,变压器匝比、漏感、开关频率等参数相互耦合,导致变换器效率优化面临多重制约。该文分析变压器匝比、漏感与软开关范围、漏感电流有效值、漏感电流峰值之间的约束关系,...单级式双有源桥(dual active bridge,DAB)DC/AC变换器控制自由度多,变压器匝比、漏感、开关频率等参数相互耦合,导致变换器效率优化面临多重制约。该文分析变压器匝比、漏感与软开关范围、漏感电流有效值、漏感电流峰值之间的约束关系,提出直接表征DAB-DC/AC变换器效率的物理量:效率敏感因子。通过研究效率敏感因子对系统损耗的影响机理,实现变换器效率最优的硬件参数设计,为多参数耦合的单级式DAB-DC/AC变换器效率优化提供理论指导。最后通过一台450 W样机验证所提理论的正确性。展开更多
We developed a one-dimensional hybrid model to simulate the DC/RF combined driven capacitively coupled plasma for argon discharges. The numerical results are used to analyze the influence of the DC source on the plasm...We developed a one-dimensional hybrid model to simulate the DC/RF combined driven capacitively coupled plasma for argon discharges. The numerical results are used to analyze the influence of the DC source on the plasma density distribution, ion energy distributions （IEDs） and ion angle distributions （IADs） on both the RF and DC electrodes. The increase in DC voltage drives more high-energy ions to the electrode applied to the DC source, which makes the IEDs at the DC electrode shift towards higher energy, and the peaks in the IADs shift towards small angle regions. At the same time, it also decreases the ion energy at the RF electrode and enlarges the incident angles of the ions, which strike the RF electrode.展开更多
Surfaces of optical elements are deposited by antireflection coatings (ARCs) to decrease the reflection of light. Surface needs treatment before depositing the ARC one of treatment processes by plasma for adhesion imp...Surfaces of optical elements are deposited by antireflection coatings (ARCs) to decrease the reflection of light. Surface needs treatment before depositing the ARC one of treatment processes by plasma for adhesion improvement and surface hardening. A comparison of RF and DC glow discharges treated CR-39 polymer films gives insight into the mechanism of these surface processes. The surface properties of the plasma-treated samples are examined by microscopy techniques include contact angle measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), infrared (IR) spectroscopy and refractive index measurements. Results show that the plasma treatment modifies the polymer surface in both composition and morphology. It is found that the surface wettability is enhanced after plasma treatment. It is found that, RF plasma is more effective than DC plasma in CR-39 surface modification, as it implants more oxygen atoms into the surface and makes the contact angle declining to a lower level.展开更多
Undoped and copper(Cu)doped zinc oxide(Zn_(1-x)Cu_(x)O,where x=0-0.065)nano crystal thin films have been deposited on glass substrate via RF/DC reactive co-sputtering technique.The aim of this work is to investigate t...Undoped and copper(Cu)doped zinc oxide(Zn_(1-x)Cu_(x)O,where x=0-0.065)nano crystal thin films have been deposited on glass substrate via RF/DC reactive co-sputtering technique.The aim of this work is to investigate the crystal structure of ZnO and Cu doped ZnO thin films and also study the effect of Cu doping on optical band gap of ZnO thin films.The identification and confirmation of the crystallinity,film thickness and surface morphology of the nano range thin films are confirmed by using X-ray diffractometer(XRD),scanning electron microscope and atomic force microscope.The XRD peak at a diffractive angle of 34.44°and Miller indices at(002)confirms the ZnO thin films.Crystallite size of undoped ZnO thin films is 27 nm and decreases from 27 nm to 22 nm with increasing the atomic fraction of Cu(x_(Cu))in the ZnO thin films from 0 to 6.5%respectively,which is calculated from XRD(002)peaks.The different bonding information of all deposited films was investigated by Fourier transform infrared spectrometer in the range of wave number between 400 cm^(-1) to 4000 cm^(-1).Optical band gap energy of all deposited thin films was analyzed by ultraviolet visible spectrophotometer,which varies from 3.35 eV to 3.19 eV with the increase of x_(Cu) from 0 to 6.5%respectively.Urbach energy of the deposited thin films increases from 115 meV to 228 meV with the increase of x_(Cu) from 0 to 6.5% respectively.展开更多
文摘Current-voltage （I-V） characteristics of a non-transferred DC arc plasma spray torch operated in argon at vacuum are reported. The arc voltage is of negative characteristics for a current below 200 A, fiat for a current between 200 A to 250 A and positive for a current beyond 250 A. The voltage increases slowly with the increase in carrier gas of arc. The rate of change in voltage with currents is about 3-4 V/100 A at a gas flow rate of about 1-1.5 V/10 standard liter per minute （slpm）. The I-V characteristics of the DC plasma torch are of a shape of hyperbola. Arc power increases with the argon flow rate. and the thermal efficiency of the torch acts in a similar way. The thermal efficiency of the non-transferred DC plasmatron is about 65-78%.
文摘This research investigates the influence of indoor and outdoor factors on photovoltaic(PV)power generation at Utrecht University to accurately predict PV system performance by identifying critical impact factors and improving renewable energy efficiency.To predict plant efficiency,nineteen variables are analyzed,consisting of nine indoor photovoltaic panel characteristics(Open Circuit Voltage(Voc),Short Circuit Current(Isc),Maximum Power(Pmpp),Maximum Voltage(Umpp),Maximum Current(Impp),Filling Factor(FF),Parallel Resistance(Rp),Series Resistance(Rs),Module Temperature)and ten environmental factors(Air Temperature,Air Humidity,Dew Point,Air Pressure,Irradiation,Irradiation Propagation,Wind Speed,Wind Speed Propagation,Wind Direction,Wind Direction Propagation).This study provides a new perspective not previously addressed in the literature.In this study,different machine learning methods such as Multilayer Perceptron(MLP),Multivariate Adaptive Regression Spline(MARS),Multiple Linear Regression(MLR),and Random Forest(RF)models are used to predict power values using data from installed PVpanels.Panel values obtained under real field conditions were used to train the models,and the results were compared.The Multilayer Perceptron(MLP)model was achieved with the highest classification accuracy of 0.990%.The machine learning models used for solar energy forecasting show high performance and produce results close to actual values.Models like Multi-Layer Perceptron(MLP)and Random Forest(RF)can be used in diverse locations based on load demand.
文摘传统桥式全波RF-DC变换电路在设计过程中忽略了二极管导通损耗,从而影响系统效率。采用了E类零电压开关(Zero Voltage Switching,ZVS)RF-DC变换电路,设计了谐振频率为8 MHz,输入功率为1.21 W的无线电力传输系统接收模块。并利用multisim软件进行了仿真。结果表明,该设计方法降低了二极管导通损耗,有效避免了传统桥式全波RF-DC变换电路存在的缺陷,效率可达92%。
文摘单级式双有源桥(dual active bridge,DAB)DC/AC变换器控制自由度多,变压器匝比、漏感、开关频率等参数相互耦合,导致变换器效率优化面临多重制约。该文分析变压器匝比、漏感与软开关范围、漏感电流有效值、漏感电流峰值之间的约束关系,提出直接表征DAB-DC/AC变换器效率的物理量:效率敏感因子。通过研究效率敏感因子对系统损耗的影响机理,实现变换器效率最优的硬件参数设计,为多参数耦合的单级式DAB-DC/AC变换器效率优化提供理论指导。最后通过一台450 W样机验证所提理论的正确性。
基金supported by the Scientific Foundation from Ministry of Education of China (No.N090305004)Doctor Startup Foundation Program of Liaoning Province (No.20111008)
文摘We developed a one-dimensional hybrid model to simulate the DC/RF combined driven capacitively coupled plasma for argon discharges. The numerical results are used to analyze the influence of the DC source on the plasma density distribution, ion energy distributions （IEDs） and ion angle distributions （IADs） on both the RF and DC electrodes. The increase in DC voltage drives more high-energy ions to the electrode applied to the DC source, which makes the IEDs at the DC electrode shift towards higher energy, and the peaks in the IADs shift towards small angle regions. At the same time, it also decreases the ion energy at the RF electrode and enlarges the incident angles of the ions, which strike the RF electrode.
文摘Surfaces of optical elements are deposited by antireflection coatings (ARCs) to decrease the reflection of light. Surface needs treatment before depositing the ARC one of treatment processes by plasma for adhesion improvement and surface hardening. A comparison of RF and DC glow discharges treated CR-39 polymer films gives insight into the mechanism of these surface processes. The surface properties of the plasma-treated samples are examined by microscopy techniques include contact angle measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), infrared (IR) spectroscopy and refractive index measurements. Results show that the plasma treatment modifies the polymer surface in both composition and morphology. It is found that the surface wettability is enhanced after plasma treatment. It is found that, RF plasma is more effective than DC plasma in CR-39 surface modification, as it implants more oxygen atoms into the surface and makes the contact angle declining to a lower level.
基金Maulana Azad National Fellowship(MANF)Scheme of University Grants Commission,New Delhi,India。
文摘Undoped and copper(Cu)doped zinc oxide(Zn_(1-x)Cu_(x)O,where x=0-0.065)nano crystal thin films have been deposited on glass substrate via RF/DC reactive co-sputtering technique.The aim of this work is to investigate the crystal structure of ZnO and Cu doped ZnO thin films and also study the effect of Cu doping on optical band gap of ZnO thin films.The identification and confirmation of the crystallinity,film thickness and surface morphology of the nano range thin films are confirmed by using X-ray diffractometer(XRD),scanning electron microscope and atomic force microscope.The XRD peak at a diffractive angle of 34.44°and Miller indices at(002)confirms the ZnO thin films.Crystallite size of undoped ZnO thin films is 27 nm and decreases from 27 nm to 22 nm with increasing the atomic fraction of Cu(x_(Cu))in the ZnO thin films from 0 to 6.5%respectively,which is calculated from XRD(002)peaks.The different bonding information of all deposited films was investigated by Fourier transform infrared spectrometer in the range of wave number between 400 cm^(-1) to 4000 cm^(-1).Optical band gap energy of all deposited thin films was analyzed by ultraviolet visible spectrophotometer,which varies from 3.35 eV to 3.19 eV with the increase of x_(Cu) from 0 to 6.5%respectively.Urbach energy of the deposited thin films increases from 115 meV to 228 meV with the increase of x_(Cu) from 0 to 6.5% respectively.
