In this work, enhancement of the light extraction efficiency of a 590 nm AIGaInP light-emitting diodes （LED） with a reflective top electrode （RTE） was investigated. A distributed Bragg reflector （DBR）, consistin...In this work, enhancement of the light extraction efficiency of a 590 nm AIGaInP light-emitting diodes （LED） with a reflective top electrode （RTE） was investigated. A distributed Bragg reflector （DBR）, consisting of AIAs/AIGaAs pairs, grown on an AlGaInP structure was used as a reflector for a reflective top electrode. It was found that a higher output power was observed from the AIGalnP LED with a RTE than from a conventional one. In addition, it was noted that the improvement in the output power depends strongly on the reflectivity of the reflector and that it exhibits a more effective performance with low injection currents. The increase in the optical output power was attributed to the enhanced extraction efficiency caused by a reduction of light absorbed from the emission region to top electrode through the RTE.展开更多
Because of the action of strong magnetic forces, it's difficult to avoid end winding vibration in the large turbo-generator stator. Sometimes it leads to the occurrence of accidents and affects the normal operatio...Because of the action of strong magnetic forces, it's difficult to avoid end winding vibration in the large turbo-generator stator. Sometimes it leads to the occurrence of accidents and affects the normal operation of the generator. This paper firstly lays out the calculation method for end winding magnetic force. Second, based on the structure of large machines, the natural vibration frequency equation and forced oscillation equation is set up. Third, through the analysis of magnetic force calculation and vibration on the end winding of turbo-generator, it will be shown that the end winding vibration is related to the magnetic force and the position of winding binds as well as binding tightness. We can ease the winding vibration by distributing binding position appropriately or add more bindings, and test the concept through experimental data.展开更多
The South China Sea is rich in wind and wave energy resources,and the wind-wave combined power generation device is currently in the concept research and development stage.In recent years,extreme sea conditions such a...The South China Sea is rich in wind and wave energy resources,and the wind-wave combined power generation device is currently in the concept research and development stage.In recent years,extreme sea conditions such as super typhoons have frequently occurred,which poses a serious challenge to the safety of offshore floating platforms.In view of the lack of safety analysis of wind-wave combined power generation devices in extreme sea conditions at present,this paper takes the OC4-WEC combined with semi-submersible wind turbine(Semi-OC4)and the oscillating buoy wave energy converter as the research object,and establishes a mesoscale WRF-SWANFVCOM(W-S-F)real-time coupling platform based on the model coupling Toolkit(MCT)to analyze the spatial and temporal evolution of wind-wave-current in offshore wind farms during the whole process of super typhoon“Rammasun”transit.Combined with the medium/small scale nested method,the flow field characteristics of OC4-WEC platform are analyzed.The results show that the simulation accuracy of the established W-S-F platform for typhoon track is 42.51%higher than that of the single WRF model.Under the action of typhoon-wave-current,the heave motion amplitude of OC4-WEC platform is reduced by 38.1%,the surge motion amplitude is reduced by 26.7%,and the pitch motion amplitude is reduced by 23.4%.展开更多
Performance characteristics data of solar photovoltaic （PV） cell/module are conventionally obtained under standard testing conditions. In the present work, the performance of PV modules under extreme temperatures an...Performance characteristics data of solar photovoltaic （PV） cell/module are conventionally obtained under standard testing conditions. In the present work, the performance of PV modules under extreme temperatures and insolations experienced in State of Qatar was utilized to aid presenting a simplified characterization approach for the special case of arid environmental conditions. The chosen model was the well-known single diode model with both series and parallel resistors for greater accuracy. The modeling technique was validated by comparing the numerically calculated electrical characteristics with experimentally obtained data using two approaches： a single indoor fixed monocrystalline PV module inside a solar simulation chamber which physically simulated different weather scenarios by changing irradiation intensities and temperature, and a set of outdoor fixed polycrystalline PV modules. The result of the indoor experiment was presented in form of performance curves, and the outdoor experiment results in a monthly accumulated power production chart format. Both illustration types showed acceptable tolerance.展开更多
The effect of L-cysteine in different concentrations on the bioleaching of Ni-Cu sulfide was studied with an extremely thermophilic archaea,Acidianus manzaensis. It is found that adding certain amounts of L-cysteine t...The effect of L-cysteine in different concentrations on the bioleaching of Ni-Cu sulfide was studied with an extremely thermophilic archaea,Acidianus manzaensis. It is found that adding certain amounts of L-cysteine to the bioleaching system of Ni-Cu sulfide largely enhances the leaching rate. X-ray diffraction (XRD) patterns show the change of bioleached solid residues and the effect of L-cysteine on the surface charges of minerals. Zeta potential and IR spectra of mineral surface show that the interaction between L-cysteine and mineral leads to the formation of metal complex,which is propitious to the bioleaching of Ni-Cu sulfide by Acidianus manzaensis.展开更多
Electron transport properties of a triple-terminal Aharonov-Bohm interferometer are theoretically studied.By applying a Rashba spin-orbit coupling to a quantum dot locally, we find that remarkable spin polarization co...Electron transport properties of a triple-terminal Aharonov-Bohm interferometer are theoretically studied.By applying a Rashba spin-orbit coupling to a quantum dot locally, we find that remarkable spin polarization comesabout in the electron transport process with tuning the structure parameters, i.e., the magnetic flux or quantum dotlevels. When the quantum dot levels are aligned with the Fermi level, there only appear spin polarization in thisstructure by the presence of an appropriate magnetic flux. However, in absence of magnetic flux spin polarization andspin separation can be simultaneously realized with the adjustment of quantum dot levels, namely, an incident electronfrom one terminal can select a specific terminal to depart from the quantum dots according to its spin state.展开更多
文摘In this work, enhancement of the light extraction efficiency of a 590 nm AIGaInP light-emitting diodes （LED） with a reflective top electrode （RTE） was investigated. A distributed Bragg reflector （DBR）, consisting of AIAs/AIGaAs pairs, grown on an AlGaInP structure was used as a reflector for a reflective top electrode. It was found that a higher output power was observed from the AIGalnP LED with a RTE than from a conventional one. In addition, it was noted that the improvement in the output power depends strongly on the reflectivity of the reflector and that it exhibits a more effective performance with low injection currents. The increase in the optical output power was attributed to the enhanced extraction efficiency caused by a reduction of light absorbed from the emission region to top electrode through the RTE.
基金This work is supported by the National Natural Science Foun- dation of China under Grant 51105261.
文摘Because of the action of strong magnetic forces, it's difficult to avoid end winding vibration in the large turbo-generator stator. Sometimes it leads to the occurrence of accidents and affects the normal operation of the generator. This paper firstly lays out the calculation method for end winding magnetic force. Second, based on the structure of large machines, the natural vibration frequency equation and forced oscillation equation is set up. Third, through the analysis of magnetic force calculation and vibration on the end winding of turbo-generator, it will be shown that the end winding vibration is related to the magnetic force and the position of winding binds as well as binding tightness. We can ease the winding vibration by distributing binding position appropriately or add more bindings, and test the concept through experimental data.
基金jointly funded by the National Key Research and Development Projects(No.2017YFE0132000)the National Natural Science Foundation of China(Nos.5211101879,52078251,52108456)the Natural Science Foundation of Jiangsu Province(Nos.BK20211518,BK20210309)
文摘The South China Sea is rich in wind and wave energy resources,and the wind-wave combined power generation device is currently in the concept research and development stage.In recent years,extreme sea conditions such as super typhoons have frequently occurred,which poses a serious challenge to the safety of offshore floating platforms.In view of the lack of safety analysis of wind-wave combined power generation devices in extreme sea conditions at present,this paper takes the OC4-WEC combined with semi-submersible wind turbine(Semi-OC4)and the oscillating buoy wave energy converter as the research object,and establishes a mesoscale WRF-SWANFVCOM(W-S-F)real-time coupling platform based on the model coupling Toolkit(MCT)to analyze the spatial and temporal evolution of wind-wave-current in offshore wind farms during the whole process of super typhoon“Rammasun”transit.Combined with the medium/small scale nested method,the flow field characteristics of OC4-WEC platform are analyzed.The results show that the simulation accuracy of the established W-S-F platform for typhoon track is 42.51%higher than that of the single WRF model.Under the action of typhoon-wave-current,the heave motion amplitude of OC4-WEC platform is reduced by 38.1%,the surge motion amplitude is reduced by 26.7%,and the pitch motion amplitude is reduced by 23.4%.
文摘Performance characteristics data of solar photovoltaic （PV） cell/module are conventionally obtained under standard testing conditions. In the present work, the performance of PV modules under extreme temperatures and insolations experienced in State of Qatar was utilized to aid presenting a simplified characterization approach for the special case of arid environmental conditions. The chosen model was the well-known single diode model with both series and parallel resistors for greater accuracy. The modeling technique was validated by comparing the numerically calculated electrical characteristics with experimentally obtained data using two approaches： a single indoor fixed monocrystalline PV module inside a solar simulation chamber which physically simulated different weather scenarios by changing irradiation intensities and temperature, and a set of outdoor fixed polycrystalline PV modules. The result of the indoor experiment was presented in form of performance curves, and the outdoor experiment results in a monthly accumulated power production chart format. Both illustration types showed acceptable tolerance.
基金Projects(50621063, 30400010) supported by the National Natural Science Foundation of ChinaProject(2010CB630903) supported by the National Basic Research Program of China
文摘The effect of L-cysteine in different concentrations on the bioleaching of Ni-Cu sulfide was studied with an extremely thermophilic archaea,Acidianus manzaensis. It is found that adding certain amounts of L-cysteine to the bioleaching system of Ni-Cu sulfide largely enhances the leaching rate. X-ray diffraction (XRD) patterns show the change of bioleached solid residues and the effect of L-cysteine on the surface charges of minerals. Zeta potential and IR spectra of mineral surface show that the interaction between L-cysteine and mineral leads to the formation of metal complex,which is propitious to the bioleaching of Ni-Cu sulfide by Acidianus manzaensis.
基金Supported by the National Natural Science Foundation of China under Grant No.10847109the Education Department of Liaoning Province under Grant No.2009A309
文摘Electron transport properties of a triple-terminal Aharonov-Bohm interferometer are theoretically studied.By applying a Rashba spin-orbit coupling to a quantum dot locally, we find that remarkable spin polarization comesabout in the electron transport process with tuning the structure parameters, i.e., the magnetic flux or quantum dotlevels. When the quantum dot levels are aligned with the Fermi level, there only appear spin polarization in thisstructure by the presence of an appropriate magnetic flux. However, in absence of magnetic flux spin polarization andspin separation can be simultaneously realized with the adjustment of quantum dot levels, namely, an incident electronfrom one terminal can select a specific terminal to depart from the quantum dots according to its spin state.
