Time-dependent thermal simulation of ridge-geometry InGaN laser diodes is carried out with a two-dimensional model. A high temperature in the waveguide layer and a large temperature step between the regions under and ...Time-dependent thermal simulation of ridge-geometry InGaN laser diodes is carried out with a two-dimensional model. A high temperature in the waveguide layer and a large temperature step between the regions under and outside the ridge are generated due to the poor thermal conductivity of the sapphire substrate and the large threshold current and voltage. The temperature step is thought to have a strong influence on the characteristics of the laser diodes. Time-resolved measurements of light-current curves,spectra, and the far-field pattern of the InGaN laser diodes under pulsed operation are performed. The results show that the thermal lensing effect improves the confinement of the higher order modes and leads to a lower threshold current and a higher slope efficiency of the device while the high temperature in the active layer results in a drastic decrease in the slope efficiency.展开更多
Two kinds of monolithically fabricated circuits are demonstrated in GaAs-based material systems using resonant tunneling diodes（RTD） and metal-semiconductor-metal photo detectors（MSM PD）. The electronic characteri...Two kinds of monolithically fabricated circuits are demonstrated in GaAs-based material systems using resonant tunneling diodes（RTD） and metal-semiconductor-metal photo detectors（MSM PD）. The electronic characteristics of these fabricated RTD devices,MSM devices,and integrated circuits are tested at room temperature. The results show that the current peak-to-valley ratio is 4,and the photocurrent at 5V is enhanced by a factor of nearly 9,from 2 to about 18μA by use of recessed electrodes. The working theory and logical functions of the circuits are validated.展开更多
Current leads are used to connect the superconducting magnets in cryogenic temperature to the power station in room temperature. It is the main source of heat leak into the eryostat of magnets on static operation. Thi...Current leads are used to connect the superconducting magnets in cryogenic temperature to the power station in room temperature. It is the main source of heat leak into the eryostat of magnets on static operation. This paper presents the optimized methods of the leads for BEPC Ⅱ , and the effects of different cross section ar- ea on the heat leak, temperature profile as well as the voltage drop of the leads. The multi-tube structure is adopted and improved for the leads. The results of numerical simulation using CFD software package Fluent6. 0 for the muhi-tube-structure leads are presented, which can be used to improve the design of the leads.展开更多
Induction motor is a multi-parameter, non-linear and strong coupling system, which requires efficient control algorithms. In this paper, rotor flux oriented control （FOC） algorithm based on voltage source inverter-f...Induction motor is a multi-parameter, non-linear and strong coupling system, which requires efficient control algorithms. In this paper, rotor flux oriented control （FOC） algorithm based on voltage source inverter-fed is deduced in detail, including stator voltage compensation, closed-loop PI parameters＇ calculation of torque and rotor flux. FOC＇ s Simulink model is setup to simulate torque and rotor flux＇s response. At last, the experimental results are shown.展开更多
This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable cond...This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable conductor temperature as well as load current determination principles are proposed. On one hand, the principles are based on mechanical limitations; on the other hand, they are based on thermal limitations. The simulation tasks were based on specific data information of three existing overhead lines of Latvian power system as well as the planned 330 kV overhead line. Moreover, the special thermovision device was used for precious determination of conductor temperature of the existing transmission lines. The simulation results of the obtained data are reviewed in the paper.展开更多
The P+ α-Si /N+ polycrystalline solar cell is molded using the AMPS-1D device simulator to explore the new high efficiency thin film poly-silicon solar cell. In order to analyze the characteristics of this device and...The P+ α-Si /N+ polycrystalline solar cell is molded using the AMPS-1D device simulator to explore the new high efficiency thin film poly-silicon solar cell. In order to analyze the characteristics of this device and the thickness of N+ poly-silicon, we consider the impurity concentration in the N+ poly-silicon layer and the work function of transparent conductive oxide (TCO) in front contact in the calculation. The thickness of N+ poly-silicon has little impact on the device when the thickness varies from 20 μm to 300 μm. The effects of impurity concentration in polycrystalline are analyzed. The conclusion is drawn that the open-circuit voltage (Voc) of P+ α-Si /N+ polycrystalline solar cell is very high, reaching 752 mV, and the conversion efficiency reaches 9.44%. Therefore, based on the above optimum parameters the study on the device formed by P+ α-Si/N+ poly-silicon is significant in exploring the high efficiency poly-silicon solar cell.展开更多
According to the equivalent circuit model(ECM),finite element model(FEM) and physical experiment,the LIDEP force induced by the spatial variations of the phase of AC electric fields produced by the bright and dark reg...According to the equivalent circuit model(ECM),finite element model(FEM) and physical experiment,the LIDEP force induced by the spatial variations of the phase of AC electric fields produced by the bright and dark regions on the photoconductive layer was demonstrated.Besides,the phenomenon of the light-induced electro-rotation(LIER) caused by the light-induced rotating electric field was confirmed numerically and experimentally for the first time.It may be helpful to go out of the dilemma that only the dipole moment model,based on the effect of light-induced partial potentials,can be used for LIDEP theoretical calculation currently.Through the FEM simulation and the electro-rotating experiment of yeast cells,it was found that the direction of yeast's LIER is relevant to the distance between its location and the edge of optical electrode,and the spin velocity of LIER is inversely proportional to that distance.Nevertheless,the LIER torques in the three-electrode mode show a non-uniform distribution where the LIDEP forces are harmful for a particle spinning stably around a fixed axis.Moreover,a four-electrode double-layer mode was proposed for the first time and the finite element simulation results agreed with the expected design,suggesting a new way for the dielectric spectrum measurement based on LIER.展开更多
Objective:To observe the efficacy of electroacupuncture(EA)plus Yi Jin Jing(Sinew-transforming Qigong Exercises)for knee osteoarthritis(KOA).Methods:A total of 60 patients with KOA were divided into an observation gro...Objective:To observe the efficacy of electroacupuncture(EA)plus Yi Jin Jing(Sinew-transforming Qigong Exercises)for knee osteoarthritis(KOA).Methods:A total of 60 patients with KOA were divided into an observation group and a control group according to the random number table method,with 30 cases in each group.Patients in the observation group received the treatment of EA plus Yi Jin Jing(Sinew-transforming Qigong Exercises),while patients in the control group only received EA treatment.Both groups were treated for 5 weeks.The changes of Western Ontario and McMaster Universities Osteoarthritis Index(WOMAC)and visual analog scale(VAS)scores in the two groups were observed after treatment.Results:After treatment,the total effective rate in the observation group(92.3%)was significantly higher than that in the control group(70.0%),(P<0.05);the WOMAC and VAS scores in both groups were significantly lower than those before treatment,showing statistical significance(all P<0.01);there were significant differences in the post-treatment changes in the WOMAC and VAS scores between the two groups(P<0.05,P<0.01).Conclusion:EA plus Yi Jin Jing(Sinew-transforming Qigong Exercises)is clinically effective for KOA.This combined treatment can alleviate clinical symptoms.展开更多
Molecular dynamics simulation (MDS) is used to study the thermodynamic properties and transport coefficients of an argon system with Lennend-Jones potential. The results on the velocity distribution,mean free path, me...Molecular dynamics simulation (MDS) is used to study the thermodynamic properties and transport coefficients of an argon system with Lennend-Jones potential. The results on the velocity distribution,mean free path, mean collision time, specific heat and self-diffusion coefficient agree well with the existing theoretical/ experimental data. It shows that molecular dynamics method is another bridge to connect microworld and macroworld.展开更多
The thermal conductivity of complex fluid materials （dusty plasmas） has been explored through novel Evan-Gillan homogeneous non-equilibrium molecular dynamic （HNEMD） algorithm. The thermal conductivity coefficient...The thermal conductivity of complex fluid materials （dusty plasmas） has been explored through novel Evan-Gillan homogeneous non-equilibrium molecular dynamic （HNEMD） algorithm. The thermal conductivity coefficient obtained from HNEMD is dependent on various plasma parameters （T,k）. The proposed algorithm gives accurate results with fast convergence and small size effect over a wide range of plasma parameters. The cross microscopic heat energy current is discussed in association with variation of temperature （1/Г） and external perturbations （Pz）. The thermal conductivity obtained from HNEMD simulations is found to be very good agreement and more reliable than previously known numerical techniques of equilibrium molecular dynarnic, nonequilibrium molecular dynamic simulations. Our new investigations point to an effective conclusion that the thermal conductivity of complex dusty plasmas is dependent on an extensive range of plasma coupling （P） and screening parameter （k） and it varies by the alteration in these parameters. It is also shown that a different approach is used for computations of thermal conductivity in 2D complex plasmas and can be appropriate method for behaviors of complex systems.展开更多
文摘Time-dependent thermal simulation of ridge-geometry InGaN laser diodes is carried out with a two-dimensional model. A high temperature in the waveguide layer and a large temperature step between the regions under and outside the ridge are generated due to the poor thermal conductivity of the sapphire substrate and the large threshold current and voltage. The temperature step is thought to have a strong influence on the characteristics of the laser diodes. Time-resolved measurements of light-current curves,spectra, and the far-field pattern of the InGaN laser diodes under pulsed operation are performed. The results show that the thermal lensing effect improves the confinement of the higher order modes and leads to a lower threshold current and a higher slope efficiency of the device while the high temperature in the active layer results in a drastic decrease in the slope efficiency.
文摘Two kinds of monolithically fabricated circuits are demonstrated in GaAs-based material systems using resonant tunneling diodes（RTD） and metal-semiconductor-metal photo detectors（MSM PD）. The electronic characteristics of these fabricated RTD devices,MSM devices,and integrated circuits are tested at room temperature. The results show that the current peak-to-valley ratio is 4,and the photocurrent at 5V is enhanced by a factor of nearly 9,from 2 to about 18μA by use of recessed electrodes. The working theory and logical functions of the circuits are validated.
文摘Current leads are used to connect the superconducting magnets in cryogenic temperature to the power station in room temperature. It is the main source of heat leak into the eryostat of magnets on static operation. This paper presents the optimized methods of the leads for BEPC Ⅱ , and the effects of different cross section ar- ea on the heat leak, temperature profile as well as the voltage drop of the leads. The multi-tube structure is adopted and improved for the leads. The results of numerical simulation using CFD software package Fluent6. 0 for the muhi-tube-structure leads are presented, which can be used to improve the design of the leads.
文摘Induction motor is a multi-parameter, non-linear and strong coupling system, which requires efficient control algorithms. In this paper, rotor flux oriented control （FOC） algorithm based on voltage source inverter-fed is deduced in detail, including stator voltage compensation, closed-loop PI parameters＇ calculation of torque and rotor flux. FOC＇ s Simulink model is setup to simulate torque and rotor flux＇s response. At last, the experimental results are shown.
文摘This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable conductor temperature as well as load current determination principles are proposed. On one hand, the principles are based on mechanical limitations; on the other hand, they are based on thermal limitations. The simulation tasks were based on specific data information of three existing overhead lines of Latvian power system as well as the planned 330 kV overhead line. Moreover, the special thermovision device was used for precious determination of conductor temperature of the existing transmission lines. The simulation results of the obtained data are reviewed in the paper.
基金supported by the Natural Science Foundation of Fujian Province of China (Grant No. A0220001)Science Research Project of Leshan Vocational & Technical College (Grant No. KY2011001)the Key Research Project in Science and Technology of Leshan (Grant No. 2011GZD050)
文摘The P+ α-Si /N+ polycrystalline solar cell is molded using the AMPS-1D device simulator to explore the new high efficiency thin film poly-silicon solar cell. In order to analyze the characteristics of this device and the thickness of N+ poly-silicon, we consider the impurity concentration in the N+ poly-silicon layer and the work function of transparent conductive oxide (TCO) in front contact in the calculation. The thickness of N+ poly-silicon has little impact on the device when the thickness varies from 20 μm to 300 μm. The effects of impurity concentration in polycrystalline are analyzed. The conclusion is drawn that the open-circuit voltage (Voc) of P+ α-Si /N+ polycrystalline solar cell is very high, reaching 752 mV, and the conversion efficiency reaches 9.44%. Therefore, based on the above optimum parameters the study on the device formed by P+ α-Si/N+ poly-silicon is significant in exploring the high efficiency poly-silicon solar cell.
基金supported by the Major Program of the National Natural Science Foundation of China (Grant No. 91023024)the New Century Elitist Program by Ministry of Education of China (Grant No.NCET-07-0180)the Technology Supported Research Program from Jiangsu Province (Grant No. BE2009054)
文摘According to the equivalent circuit model(ECM),finite element model(FEM) and physical experiment,the LIDEP force induced by the spatial variations of the phase of AC electric fields produced by the bright and dark regions on the photoconductive layer was demonstrated.Besides,the phenomenon of the light-induced electro-rotation(LIER) caused by the light-induced rotating electric field was confirmed numerically and experimentally for the first time.It may be helpful to go out of the dilemma that only the dipole moment model,based on the effect of light-induced partial potentials,can be used for LIDEP theoretical calculation currently.Through the FEM simulation and the electro-rotating experiment of yeast cells,it was found that the direction of yeast's LIER is relevant to the distance between its location and the edge of optical electrode,and the spin velocity of LIER is inversely proportional to that distance.Nevertheless,the LIER torques in the three-electrode mode show a non-uniform distribution where the LIDEP forces are harmful for a particle spinning stably around a fixed axis.Moreover,a four-electrode double-layer mode was proposed for the first time and the finite element simulation results agreed with the expected design,suggesting a new way for the dielectric spectrum measurement based on LIER.
文摘Objective:To observe the efficacy of electroacupuncture(EA)plus Yi Jin Jing(Sinew-transforming Qigong Exercises)for knee osteoarthritis(KOA).Methods:A total of 60 patients with KOA were divided into an observation group and a control group according to the random number table method,with 30 cases in each group.Patients in the observation group received the treatment of EA plus Yi Jin Jing(Sinew-transforming Qigong Exercises),while patients in the control group only received EA treatment.Both groups were treated for 5 weeks.The changes of Western Ontario and McMaster Universities Osteoarthritis Index(WOMAC)and visual analog scale(VAS)scores in the two groups were observed after treatment.Results:After treatment,the total effective rate in the observation group(92.3%)was significantly higher than that in the control group(70.0%),(P<0.05);the WOMAC and VAS scores in both groups were significantly lower than those before treatment,showing statistical significance(all P<0.01);there were significant differences in the post-treatment changes in the WOMAC and VAS scores between the two groups(P<0.05,P<0.01).Conclusion:EA plus Yi Jin Jing(Sinew-transforming Qigong Exercises)is clinically effective for KOA.This combined treatment can alleviate clinical symptoms.
文摘Molecular dynamics simulation (MDS) is used to study the thermodynamic properties and transport coefficients of an argon system with Lennend-Jones potential. The results on the velocity distribution,mean free path, mean collision time, specific heat and self-diffusion coefficient agree well with the existing theoretical/ experimental data. It shows that molecular dynamics method is another bridge to connect microworld and macroworld.
文摘The thermal conductivity of complex fluid materials （dusty plasmas） has been explored through novel Evan-Gillan homogeneous non-equilibrium molecular dynamic （HNEMD） algorithm. The thermal conductivity coefficient obtained from HNEMD is dependent on various plasma parameters （T,k）. The proposed algorithm gives accurate results with fast convergence and small size effect over a wide range of plasma parameters. The cross microscopic heat energy current is discussed in association with variation of temperature （1/Г） and external perturbations （Pz）. The thermal conductivity obtained from HNEMD simulations is found to be very good agreement and more reliable than previously known numerical techniques of equilibrium molecular dynarnic, nonequilibrium molecular dynamic simulations. Our new investigations point to an effective conclusion that the thermal conductivity of complex dusty plasmas is dependent on an extensive range of plasma coupling （P） and screening parameter （k） and it varies by the alteration in these parameters. It is also shown that a different approach is used for computations of thermal conductivity in 2D complex plasmas and can be appropriate method for behaviors of complex systems.
