针对煤矿井下选择性漏电保护的问题,着重围绕零序功率方向性原理对该问题进行了研究,并结合DSP(Digital Signal Processor)技术给出了一种基于TMS320LF2407A芯片的零序电压、电流相位比较方案。这一方案是通过过零触发电路捕捉零序电压...针对煤矿井下选择性漏电保护的问题,着重围绕零序功率方向性原理对该问题进行了研究,并结合DSP(Digital Signal Processor)技术给出了一种基于TMS320LF2407A芯片的零序电压、电流相位比较方案。这一方案是通过过零触发电路捕捉零序电压、电流的过零点,然后在软件上来比较零序电压、电流之间的相位关系,根据漏电故障支路与非故障支路中零序电压、电流之间相位的不同,从而实现漏电保护的选择性。同时为了验证过零触发电路的可行性,使用电子电路仿真软件Multisim9进行了触发电路的硬件仿真。最后根据选择性漏电保护的实现过程给出了软件设计流程图以及试验数据分析。展开更多
The aim of this investigation was to improve power performance of Savonius hydraulic turbine utilizing small stream for electric generation.An attempt was made to increase the power coefficient of runner by the use of...The aim of this investigation was to improve power performance of Savonius hydraulic turbine utilizing small stream for electric generation.An attempt was made to increase the power coefficient of runner by the use of flat shield plate placed upstream of the runner.The difference of the power coefficient is discussed in relation to clearance between the runner and the bottom wall and the rotation direction of the runner.The flow field around the runner was also examined visually to clarify influences of setting conditions on the power performance.From this study it was found that the power coefficient is achieved for 0.47 by only using a flat shield plate,the increase is up to 80% over the runner without the plate.Moreover,it is the proper condition that clearance ratio is 0.73 in this study.展开更多
According to the aplanatism theory, lens can be used to focus the electromagnetic wave. A piano-convex hyperboloid of revo- lution lens made of low loss material is designed for combinatorial applications with the rec...According to the aplanatism theory, lens can be used to focus the electromagnetic wave. A piano-convex hyperboloid of revo- lution lens made of low loss material is designed for combinatorial applications with the rectangle microstrip applicator in microwave hyperthermia. Results of the extensive simulations and experiments show that the introduction of the lens to the clinical used antenna can significantly improve the directivity and hence increase the microwave power density in near field. In microwave hyperthermia applications, the lens antenna will exhibit superior directivity, high gain and well thermal efficiency for tumor in superficial layer. Besides, it has small treatment area that is helpful for reducing the injury of the normal tissue around the tumor.展开更多
文摘针对煤矿井下选择性漏电保护的问题,着重围绕零序功率方向性原理对该问题进行了研究,并结合DSP(Digital Signal Processor)技术给出了一种基于TMS320LF2407A芯片的零序电压、电流相位比较方案。这一方案是通过过零触发电路捕捉零序电压、电流的过零点,然后在软件上来比较零序电压、电流之间的相位关系,根据漏电故障支路与非故障支路中零序电压、电流之间相位的不同,从而实现漏电保护的选择性。同时为了验证过零触发电路的可行性,使用电子电路仿真软件Multisim9进行了触发电路的硬件仿真。最后根据选择性漏电保护的实现过程给出了软件设计流程图以及试验数据分析。
基金supported by KAKENHI No.2231004 and Ministry of Environment
文摘The aim of this investigation was to improve power performance of Savonius hydraulic turbine utilizing small stream for electric generation.An attempt was made to increase the power coefficient of runner by the use of flat shield plate placed upstream of the runner.The difference of the power coefficient is discussed in relation to clearance between the runner and the bottom wall and the rotation direction of the runner.The flow field around the runner was also examined visually to clarify influences of setting conditions on the power performance.From this study it was found that the power coefficient is achieved for 0.47 by only using a flat shield plate,the increase is up to 80% over the runner without the plate.Moreover,it is the proper condition that clearance ratio is 0.73 in this study.
文摘According to the aplanatism theory, lens can be used to focus the electromagnetic wave. A piano-convex hyperboloid of revo- lution lens made of low loss material is designed for combinatorial applications with the rectangle microstrip applicator in microwave hyperthermia. Results of the extensive simulations and experiments show that the introduction of the lens to the clinical used antenna can significantly improve the directivity and hence increase the microwave power density in near field. In microwave hyperthermia applications, the lens antenna will exhibit superior directivity, high gain and well thermal efficiency for tumor in superficial layer. Besides, it has small treatment area that is helpful for reducing the injury of the normal tissue around the tumor.
