匿名网络旨在公开网络环境中保护用户通信隐私.自Chaum提出Mix网以来,相关研究在几十年中不断取得进展.如今,匿名网络已发展成以Mix网、DC网或PIR(private information retrieval)为基础,并结合多种设计要素,使之适用于各种应用场景和...匿名网络旨在公开网络环境中保护用户通信隐私.自Chaum提出Mix网以来,相关研究在几十年中不断取得进展.如今,匿名网络已发展成以Mix网、DC网或PIR(private information retrieval)为基础,并结合多种设计要素,使之适用于各种应用场景和威胁模型.从匿名概念出发,介绍匿名网络领域的发展情况,分类阐述代表性研究工作及其设计选择,并系统地从匿名性、延迟和带宽开销等角度进行分析.展开更多
In order to guarantee quality during mass serial production of motors, a convenient approach on how to detect and diagnose the faults of a permanent-magnetic DC motor based on armature current analysis and BP neural n...In order to guarantee quality during mass serial production of motors, a convenient approach on how to detect and diagnose the faults of a permanent-magnetic DC motor based on armature current analysis and BP neural networks was presented in this paper. The fault feature vector was directly established by analyzing the armature current. Fault features were extracted from the current using various signal processing methods including Fourier analysis, wavelet analysis and statistical methods. Then an advanced BP neural network was used to finish decision-making and separate fault patterns. Finally, the accuracy of the method in this paper was verified by analyzing the mechanism of faults theoretically. The consistency between the experimental results and the theoretical analysis shows that four kinds of representative faults of low power permanent-magnetic DC motors can be diagnosed conveniently by this method. These four faults are brush fray, open circuit of components, open weld of components and short circuit between armature coils. This method needs fewer hardware instruments than the conventional method and whole procedures can be accomplished by several software packages developed in this paper.展开更多
A novel 50 kW fast charger was proposed for electric vehicles. The proposed fast charger is divided into two main sections an AC-DC converter performing a PFC function and a DC-DC converter performing a charging funct...A novel 50 kW fast charger was proposed for electric vehicles. The proposed fast charger is divided into two main sections an AC-DC converter performing a PFC function and a DC-DC converter performing a charging function. A transformer including leakage inductances was used in the AC-DC converter in order to obtain isolation and inductance. A series-connection topology was used in the DC-DC converter between the DC-bus and outlet. This topology enables high power conversion efficiency up to 95% for the DC-DC converter. In order to reduce the impact of the 50 kW charging on the AC grid, the proposed fast charger system includes a buffering battery unit between the two main power conversion units. This leads to reductions in the power installation costs of power companies and to improvements in the power quality were verified through simulations and experimental results. on the AC grid. The performances of the proposed fast charger system展开更多
文摘匿名网络旨在公开网络环境中保护用户通信隐私.自Chaum提出Mix网以来,相关研究在几十年中不断取得进展.如今,匿名网络已发展成以Mix网、DC网或PIR(private information retrieval)为基础,并结合多种设计要素,使之适用于各种应用场景和威胁模型.从匿名概念出发,介绍匿名网络领域的发展情况,分类阐述代表性研究工作及其设计选择,并系统地从匿名性、延迟和带宽开销等角度进行分析.
文摘In order to guarantee quality during mass serial production of motors, a convenient approach on how to detect and diagnose the faults of a permanent-magnetic DC motor based on armature current analysis and BP neural networks was presented in this paper. The fault feature vector was directly established by analyzing the armature current. Fault features were extracted from the current using various signal processing methods including Fourier analysis, wavelet analysis and statistical methods. Then an advanced BP neural network was used to finish decision-making and separate fault patterns. Finally, the accuracy of the method in this paper was verified by analyzing the mechanism of faults theoretically. The consistency between the experimental results and the theoretical analysis shows that four kinds of representative faults of low power permanent-magnetic DC motors can be diagnosed conveniently by this method. These four faults are brush fray, open circuit of components, open weld of components and short circuit between armature coils. This method needs fewer hardware instruments than the conventional method and whole procedures can be accomplished by several software packages developed in this paper.
基金Project supported by Changwon National University in 2011-2012
文摘A novel 50 kW fast charger was proposed for electric vehicles. The proposed fast charger is divided into two main sections an AC-DC converter performing a PFC function and a DC-DC converter performing a charging function. A transformer including leakage inductances was used in the AC-DC converter in order to obtain isolation and inductance. A series-connection topology was used in the DC-DC converter between the DC-bus and outlet. This topology enables high power conversion efficiency up to 95% for the DC-DC converter. In order to reduce the impact of the 50 kW charging on the AC grid, the proposed fast charger system includes a buffering battery unit between the two main power conversion units. This leads to reductions in the power installation costs of power companies and to improvements in the power quality were verified through simulations and experimental results. on the AC grid. The performances of the proposed fast charger system
