The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding curren...The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding current detection results of Xieqiao coal mine, the conclusion that harmonic component of grounding current is dominated by higher harmonics with complex harmonic sources in coal mine power network system was obtained. The influences of harmonic source type and fault point position on harmonic voltage and harmonic current were analyzed theoretically. The influences of earthed fault feeder detection result and the estimation errors of parameters to earth on residual current compensation were analyzed. A new thought of residual current prediction and the selections of model method and control method were proposed on this basis. The simulation results prove that harmonic amplitudes of zero sequence voltage and zero sequence current are determined by harmonic source type as well as fault point position in coal mine power network, and also prove that zero sequence voltage detection can avoid the unstable problem of coal mine power network system caused by undercompensation of capacitive current. Finally, the experimental device of full compensation arc suppression coil is introduced.展开更多
The present paper aims to investigate the influence of the current density in the electroplating process on the microstructure, crystal texture transformations, and corrosion behavior of Ni/Co pumice multilayer nanoco...The present paper aims to investigate the influence of the current density in the electroplating process on the microstructure, crystal texture transformations, and corrosion behavior of Ni/Co pumice multilayer nanocomposite coatings. The Ni/Co pumice composite coatings were prepared by deposition of Ni, followed by the simultaneous deposition of pumice nanoparticles (NPs) in a Co matrix via an electroplating process at various current densities. Afterward, the morphology, size, topography, and crystal texture of the obtained samples were investigated. Furthermore, electrochemical methods were used to investigate the corrosion behavior of the produced coatings in a solution of 3.5wt% NaCl. The results indicated that increasing the plating current density changed the mechanism of coating growth from the cell state to the column state, in- creased the coating thickness, roughness, and texture coefficient (TC) of the Co (203) plane, and reduced the amount of pumice NPs incorporated into the Ni/Co pumice composite. The electrochemical results also indicated that increasing the current density enhanced the corrosion resistance of the Ni/Co pumice composite.展开更多
The effect of adding RE to plating bath on microstructure and corrosion resistance of Ni-Co alloy coatings prepared by pulse reversal current electrodeposition was studied by means of SEM/EDS, electrochemical analysis...The effect of adding RE to plating bath on microstructure and corrosion resistance of Ni-Co alloy coatings prepared by pulse reversal current electrodeposition was studied by means of SEM/EDS, electrochemical analysis and corrosion mass loss etc. The results show that adding proper RE to plating solution can promote the microstructure of coatings compacter, the surface smoother and the crystal finer, and improve the corrosion resistance. The coatings exhibite the highest corrosion resistance when the concentration of RE reaches 0.25 g·L -1. The reason of increasing corrosion resistance by adding RE was also investigated.展开更多
Several applications such as liquid-liquid extraction in micro-fluidic devices are concerned with the flow of two immiscible liquid phases. The commonly observed flow regimes in these systems are slug-flow and stratif...Several applications such as liquid-liquid extraction in micro-fluidic devices are concerned with the flow of two immiscible liquid phases. The commonly observed flow regimes in these systems are slug-flow and stratified flow. The latter regime in micro-channels has the inherent advantage that separation of the two liquids at the exit is efficient. Recently extraction in a stratified counter-current flow has been studied experimentally and it has been shown to be more efficient than co-current flow. An analytical as well as a numerical method to determine the steady-state solution of the corresponding convection-diffusion equation for the two flow-fields is presented. It is shown that the counter-current process is superior to the co-current process for the same set of parameters and operating conditions. A simplified model is proposed to analyse the process when diffusion in the transverse direction is not rate limiting. Different approaches to determining mass transfer coefficient are compared. The concept of log mean temperature difference used in design of heat exchangers is extended to describe mass transfer in the system.展开更多
目的:探讨经颅直流电刺激(transcranial direct current stimulation,t DCS)治疗急性CO中毒患者认知功能障碍的疗效。方法:选取15例CO中毒后认知功能障碍患者,对患者均进行常规康复治疗和t DCS治疗,治疗前后采用简易精神状态评价(minimu...目的:探讨经颅直流电刺激(transcranial direct current stimulation,t DCS)治疗急性CO中毒患者认知功能障碍的疗效。方法:选取15例CO中毒后认知功能障碍患者,对患者均进行常规康复治疗和t DCS治疗,治疗前后采用简易精神状态评价(minimum mental state examination,MMSE)量表、上肢反应时间及事件相关电位P300综合评估患者认知功能情况。结果:与治疗前相比,常规康复治疗和t DCS治疗后患者MMSE评分明显升高,上肢反应时间明显缩短且正确率显著升高,P300检测中P3波潜伏期明显缩短,波幅显著升高,差异均有统计学意义(P<0.05或P<0.01)。结论:t DCS有助于提高急性CO中毒患者认知功能。展开更多
基金The financial support from the National Natural Science Foundation of China (No. 51107143)
文摘The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding current detection results of Xieqiao coal mine, the conclusion that harmonic component of grounding current is dominated by higher harmonics with complex harmonic sources in coal mine power network system was obtained. The influences of harmonic source type and fault point position on harmonic voltage and harmonic current were analyzed theoretically. The influences of earthed fault feeder detection result and the estimation errors of parameters to earth on residual current compensation were analyzed. A new thought of residual current prediction and the selections of model method and control method were proposed on this basis. The simulation results prove that harmonic amplitudes of zero sequence voltage and zero sequence current are determined by harmonic source type as well as fault point position in coal mine power network, and also prove that zero sequence voltage detection can avoid the unstable problem of coal mine power network system caused by undercompensation of capacitive current. Finally, the experimental device of full compensation arc suppression coil is introduced.
文摘The present paper aims to investigate the influence of the current density in the electroplating process on the microstructure, crystal texture transformations, and corrosion behavior of Ni/Co pumice multilayer nanocomposite coatings. The Ni/Co pumice composite coatings were prepared by deposition of Ni, followed by the simultaneous deposition of pumice nanoparticles (NPs) in a Co matrix via an electroplating process at various current densities. Afterward, the morphology, size, topography, and crystal texture of the obtained samples were investigated. Furthermore, electrochemical methods were used to investigate the corrosion behavior of the produced coatings in a solution of 3.5wt% NaCl. The results indicated that increasing the plating current density changed the mechanism of coating growth from the cell state to the column state, in- creased the coating thickness, roughness, and texture coefficient (TC) of the Co (203) plane, and reduced the amount of pumice NPs incorporated into the Ni/Co pumice composite. The electrochemical results also indicated that increasing the current density enhanced the corrosion resistance of the Ni/Co pumice composite.
文摘The effect of adding RE to plating bath on microstructure and corrosion resistance of Ni-Co alloy coatings prepared by pulse reversal current electrodeposition was studied by means of SEM/EDS, electrochemical analysis and corrosion mass loss etc. The results show that adding proper RE to plating solution can promote the microstructure of coatings compacter, the surface smoother and the crystal finer, and improve the corrosion resistance. The coatings exhibite the highest corrosion resistance when the concentration of RE reaches 0.25 g·L -1. The reason of increasing corrosion resistance by adding RE was also investigated.
文摘Several applications such as liquid-liquid extraction in micro-fluidic devices are concerned with the flow of two immiscible liquid phases. The commonly observed flow regimes in these systems are slug-flow and stratified flow. The latter regime in micro-channels has the inherent advantage that separation of the two liquids at the exit is efficient. Recently extraction in a stratified counter-current flow has been studied experimentally and it has been shown to be more efficient than co-current flow. An analytical as well as a numerical method to determine the steady-state solution of the corresponding convection-diffusion equation for the two flow-fields is presented. It is shown that the counter-current process is superior to the co-current process for the same set of parameters and operating conditions. A simplified model is proposed to analyse the process when diffusion in the transverse direction is not rate limiting. Different approaches to determining mass transfer coefficient are compared. The concept of log mean temperature difference used in design of heat exchangers is extended to describe mass transfer in the system.
文摘目的:探讨经颅直流电刺激(transcranial direct current stimulation,t DCS)治疗急性CO中毒患者认知功能障碍的疗效。方法:选取15例CO中毒后认知功能障碍患者,对患者均进行常规康复治疗和t DCS治疗,治疗前后采用简易精神状态评价(minimum mental state examination,MMSE)量表、上肢反应时间及事件相关电位P300综合评估患者认知功能情况。结果:与治疗前相比,常规康复治疗和t DCS治疗后患者MMSE评分明显升高,上肢反应时间明显缩短且正确率显著升高,P300检测中P3波潜伏期明显缩短,波幅显著升高,差异均有统计学意义(P<0.05或P<0.01)。结论:t DCS有助于提高急性CO中毒患者认知功能。
