Reciprocal oscillographic chronopotentiogram is such a curve that can converts incisions on "(dE/dt)-E" oscillogram into peaks on "(dt/dE)-E" curve. In order to increase the sensitivity, a new tech...Reciprocal oscillographic chronopotentiogram is such a curve that can converts incisions on "(dE/dt)-E" oscillogram into peaks on "(dt/dE)-E" curve. In order to increase the sensitivity, a new technique called feeding back current was added in new circuit of obtaining reciprocal oscillgraphic chronopotentiogram. It can make capacity current be subtracted easily. Using this method, we carry out studying on principle and titration of drug.展开更多
In this study, the combined actions of waves and tidal currents in estuarine and coastal areas are considered and a 2D mathematical model for sediment transport by waves and tidal currents has been established in orth...In this study, the combined actions of waves and tidal currents in estuarine and coastal areas are considered and a 2D mathematical model for sediment transport by waves and tidal currents has been established in orthogonal curvilinear coordinates. Non-equilibrium transport equations of suspended load and bed load are used in the model. The concept of background concentration is introduced, and the formula of sediment transport capacity of tidal currents for the Oujiang River estuary is obtained. The Dou Guoren formula is employed for the sediment transport capacity of waves. Sediment transport capacity in the form of mud and the intensity of back silting are calculated by use of Luo Zaosen＇ s formula. The calculated tidal stages are in good agreement with the field data, and the calculated velocities and flow directions of 46 vertical lines for 8 cross sections are also in good agreement with the measured data. On such a basis, simulations of back silting after excavation of the waterway with a sand bar under complicated boundary conditions in the navigation channel induced by suspended load, bed load and mud by waves and tidal currents are discussed.展开更多
介绍了一起误用三同轴——同轴BNC转接器导致测量结果错误的案例,对三同轴——同轴转接器的常见转换方式和半导体器件参数测试仪电源/测量单元(Source Meter Unit,简称SMU)的内部电路进行研究,分析案例中造成测量结果错误的原因是使用...介绍了一起误用三同轴——同轴BNC转接器导致测量结果错误的案例,对三同轴——同轴转接器的常见转换方式和半导体器件参数测试仪电源/测量单元(Source Meter Unit,简称SMU)的内部电路进行研究,分析案例中造成测量结果错误的原因是使用的转接器的连接方式不适用,并通过试验予以证实。最后,给出正确使用转接器的几种常见方式,提出在半导体器件参数测量中,应根据测量电流大小、SMU的电流回路和被测器件电路,正确选用适当的三同轴转接器,并在连接后实施开路、短路和电阻负载实验进行电路验证的建议。展开更多
交替极永磁(consequent pole permanent magnet,CPPM)电机每对极下的气隙磁密不对称,在特定极槽配合下其反电动势(electromotive force,EMF)中存在2、4次等偶次谐波分量,引起额外的转矩脉动,降低转矩输出品质。为解决上述问题,提出一种...交替极永磁(consequent pole permanent magnet,CPPM)电机每对极下的气隙磁密不对称,在特定极槽配合下其反电动势(electromotive force,EMF)中存在2、4次等偶次谐波分量,引起额外的转矩脉动,降低转矩输出品质。为解决上述问题,提出一种注入多谐波电流产生的转矩补偿原有转矩脉动的控制策略。推导适用于任意次谐波磁链产生的转矩脉动通用解析模型;并基于此模型,给出利用谐波电流抑制转矩脉动的理论依据;提出在同步旋转坐标系下注入多次谐波电流的方法,抑制由2、4、5、7、11、13次谐波反电势引起的3、6、12次转矩脉动;并利用准-比例谐振控制器实现谐波电流的精确跟踪。最后,以一台三相9槽10极交替极永磁电机为例,通过不同工况下的转矩脉动抑制实验,验证所提控制策略的有效性。展开更多
无刷直流电机(Brushless DC Motor,BLDCM)作为一种高效、节能的电机类型,在石油、化工、交通等各领域得到了广泛应用。无位置传感器控制技术作为无刷直流电机控制的重要分支,通过检测电机反电动势或相电流等信息,实现电机的换相控制,无...无刷直流电机(Brushless DC Motor,BLDCM)作为一种高效、节能的电机类型,在石油、化工、交通等各领域得到了广泛应用。无位置传感器控制技术作为无刷直流电机控制的重要分支,通过检测电机反电动势或相电流等信息,实现电机的换相控制,无需额外的位置传感器,从而降低了系统成本,提高了系统可靠性。现通过分析无刷直流电机无位置传感器控制技术的研究现状,论证了现有方法的优缺点,并探讨了未来的发展方向。展开更多
文摘Reciprocal oscillographic chronopotentiogram is such a curve that can converts incisions on "(dE/dt)-E" oscillogram into peaks on "(dt/dE)-E" curve. In order to increase the sensitivity, a new technique called feeding back current was added in new circuit of obtaining reciprocal oscillgraphic chronopotentiogram. It can make capacity current be subtracted easily. Using this method, we carry out studying on principle and titration of drug.
基金This work was supported bythe National Basic Research Program(973) of China (Grant No.2003CB415206) andthe National Natural Science Foundation of China (Grant No.50379027 and No.50479004)
文摘In this study, the combined actions of waves and tidal currents in estuarine and coastal areas are considered and a 2D mathematical model for sediment transport by waves and tidal currents has been established in orthogonal curvilinear coordinates. Non-equilibrium transport equations of suspended load and bed load are used in the model. The concept of background concentration is introduced, and the formula of sediment transport capacity of tidal currents for the Oujiang River estuary is obtained. The Dou Guoren formula is employed for the sediment transport capacity of waves. Sediment transport capacity in the form of mud and the intensity of back silting are calculated by use of Luo Zaosen＇ s formula. The calculated tidal stages are in good agreement with the field data, and the calculated velocities and flow directions of 46 vertical lines for 8 cross sections are also in good agreement with the measured data. On such a basis, simulations of back silting after excavation of the waterway with a sand bar under complicated boundary conditions in the navigation channel induced by suspended load, bed load and mud by waves and tidal currents are discussed.
文摘介绍了一起误用三同轴——同轴BNC转接器导致测量结果错误的案例,对三同轴——同轴转接器的常见转换方式和半导体器件参数测试仪电源/测量单元(Source Meter Unit,简称SMU)的内部电路进行研究,分析案例中造成测量结果错误的原因是使用的转接器的连接方式不适用,并通过试验予以证实。最后,给出正确使用转接器的几种常见方式,提出在半导体器件参数测量中,应根据测量电流大小、SMU的电流回路和被测器件电路,正确选用适当的三同轴转接器,并在连接后实施开路、短路和电阻负载实验进行电路验证的建议。
文摘交替极永磁(consequent pole permanent magnet,CPPM)电机每对极下的气隙磁密不对称,在特定极槽配合下其反电动势(electromotive force,EMF)中存在2、4次等偶次谐波分量,引起额外的转矩脉动,降低转矩输出品质。为解决上述问题,提出一种注入多谐波电流产生的转矩补偿原有转矩脉动的控制策略。推导适用于任意次谐波磁链产生的转矩脉动通用解析模型;并基于此模型,给出利用谐波电流抑制转矩脉动的理论依据;提出在同步旋转坐标系下注入多次谐波电流的方法,抑制由2、4、5、7、11、13次谐波反电势引起的3、6、12次转矩脉动;并利用准-比例谐振控制器实现谐波电流的精确跟踪。最后,以一台三相9槽10极交替极永磁电机为例,通过不同工况下的转矩脉动抑制实验,验证所提控制策略的有效性。
文摘无刷直流电机(Brushless DC Motor,BLDCM)作为一种高效、节能的电机类型,在石油、化工、交通等各领域得到了广泛应用。无位置传感器控制技术作为无刷直流电机控制的重要分支,通过检测电机反电动势或相电流等信息,实现电机的换相控制,无需额外的位置传感器,从而降低了系统成本,提高了系统可靠性。现通过分析无刷直流电机无位置传感器控制技术的研究现状,论证了现有方法的优缺点,并探讨了未来的发展方向。
