According to statistic data,machinery faults contribute to largest proportion of High-voltage circuit breaker failures,and traditional maintenance methods exist some disadvantages for that issue.Therefore,based on the...According to statistic data,machinery faults contribute to largest proportion of High-voltage circuit breaker failures,and traditional maintenance methods exist some disadvantages for that issue.Therefore,based on the wavelet packet decomposition approach and support vector machines,a new diagnosis model is proposed for such fault diagnoses in this study.The vibration eigenvalue extraction is analyzed through wavelet packet decomposition,and a four-layer support vector machine is constituted as a fault classifier.The Gaussian radial basis function is employed as the kernel function for the classifier.The penalty parameter c and kernel parameterδof the support vector machine are vital for the diagnostic accuracy,and these parameters must be carefully predetermined.Thus,a particle swarm optimizationsupport vector machine model is developed in which the optimal parameters c andδfor the support vector machine in each layer are determined by the particle swarm algorithm.The validity of this fault diagnosis model is determined with a real dataset from the operation experiment.Moreover,comparative investigations of fault diagnosis experiments with a normal support vector machine and a particle swarm optimization back-propagation neural network are also implemented.The results indicate that the proposed fault diagnosis model yields better accuracy and e-ciency than these other models.展开更多
When a metal makes intimate contact with a semiconductor material, a Schottky barrier may be created. The Schottky contact has many important applications in the integrated circuit （IC） electronics field. The parame...When a metal makes intimate contact with a semiconductor material, a Schottky barrier may be created. The Schottky contact has many important applications in the integrated circuit （IC） electronics field. The parameters of such contacts can be determined from their current-voltage （I-V） characteristics. The literature contains many proposals for extracting the contact parameters using graphical methods. However, such methods are generally applicable only to contacts with a forward bias, whereas many Schottky contacts actually operate un- der a reverse bias. Accordingly, the present study proposed a generalized reverse current-voltage （I-V） plot which enables the series resis- tance, barrier height, and ideality factor of a reverse biased Schottky contact to be extracted from a single set of I-V measurements. A theo- retical derivation of the proposed approach was presented and a series of validation tests were then performed. The results show that the pro- posed method is capable of extracting reliable estimates of the contact parameters even in the presence of experimental noise.展开更多
This paper presents a low-phase-noise LC voltage-controlled oscillator (LC-VCO) with top resistive biasing in subthreshold region. The subthreshold LC-VCO has low-power and low-phase-noise due to its high transconduct...This paper presents a low-phase-noise LC voltage-controlled oscillator (LC-VCO) with top resistive biasing in subthreshold region. The subthreshold LC-VCO has low-power and low-phase-noise due to its high transconductance efficiency and low gate bias condition. The top resistive biasing has more benefit with the feature of phase noise than MOS current source since it can support the low-noise characteristics and large output swing. The LC-VCO designed in 130-nm CMOS process with 0.7-V supply voltage achieves phase noise of -116 dBc/Hz at 200 kHz offset with tuning range of 398 MHz to 408 MHz covering medical implant communication service (MICS) band.展开更多
As semiconductor manufacturing migrates to more advanced technology nodes, accelerated aging effect for nanoscale devices poses as a key challenge for designers to find countermeasures that effectively mitigate the de...As semiconductor manufacturing migrates to more advanced technology nodes, accelerated aging effect for nanoscale devices poses as a key challenge for designers to find countermeasures that effectively mitigate the degradation and prolong system's lifetime. Negative Bias Temperature Instability (NBTI) is emerging as one of the major reliability concerns. Two software tools for NBTI analyzing are proposed in this paper, one for transistor-level, and the other for gate-level. The transistor-level can be used to estimate the delay degradation due to NBTI effect very accurately, while the gate-level can be used for repeat analysis in circuit optimization because of its fast computing speed.展开更多
随着电力负荷快速增长,电力系统的故障电流水平持续上升,甚至超出了现有断路器的开断能力;为有效限制故障电流,超导故障限流器(superconducting fault current limiter,SFCL)逐渐投入应用。SFCL在正常运行时呈现零阻抗,故障发生后迅速...随着电力负荷快速增长,电力系统的故障电流水平持续上升,甚至超出了现有断路器的开断能力;为有效限制故障电流,超导故障限流器(superconducting fault current limiter,SFCL)逐渐投入应用。SFCL在正常运行时呈现零阻抗,故障发生后迅速转为高阻抗,可作为配合断路器开断的理想选择,提高电力系统的运行安全性。介绍了一种磁偏置型超导故障限流器(magneto-biased superconducting fault current limiter,MBSFCL),提出了考虑短路电流非周期分量影响的MBSFCL设计方法,对于MBSFCL的制造具有一定的指导意义。通过搭建仿真模型,验证了所提出方法的可行性,并对MBSFCL的限流特性进行了深入分析,讨论了不同非周期分量对断路器的开断影响,以及MBSFCL中电感、电阻参数变化对短路电流及其分量的限流效果影响。分析结果表明,在所提出MBSFCL设计方法中必须考虑非周期分量,且MBSFCL的电阻参数变化对短路电流的抑制效果更为显著。展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51705372)National Science and Technology Project of the Power Grid of China(Grant No.5211DS16002L).
文摘According to statistic data,machinery faults contribute to largest proportion of High-voltage circuit breaker failures,and traditional maintenance methods exist some disadvantages for that issue.Therefore,based on the wavelet packet decomposition approach and support vector machines,a new diagnosis model is proposed for such fault diagnoses in this study.The vibration eigenvalue extraction is analyzed through wavelet packet decomposition,and a four-layer support vector machine is constituted as a fault classifier.The Gaussian radial basis function is employed as the kernel function for the classifier.The penalty parameter c and kernel parameterδof the support vector machine are vital for the diagnostic accuracy,and these parameters must be carefully predetermined.Thus,a particle swarm optimizationsupport vector machine model is developed in which the optimal parameters c andδfor the support vector machine in each layer are determined by the particle swarm algorithm.The validity of this fault diagnosis model is determined with a real dataset from the operation experiment.Moreover,comparative investigations of fault diagnosis experiments with a normal support vector machine and a particle swarm optimization back-propagation neural network are also implemented.The results indicate that the proposed fault diagnosis model yields better accuracy and e-ciency than these other models.
基金financially supported by the Fund under Grant No.NSC95-2516-S-020-003
文摘When a metal makes intimate contact with a semiconductor material, a Schottky barrier may be created. The Schottky contact has many important applications in the integrated circuit （IC） electronics field. The parameters of such contacts can be determined from their current-voltage （I-V） characteristics. The literature contains many proposals for extracting the contact parameters using graphical methods. However, such methods are generally applicable only to contacts with a forward bias, whereas many Schottky contacts actually operate un- der a reverse bias. Accordingly, the present study proposed a generalized reverse current-voltage （I-V） plot which enables the series resis- tance, barrier height, and ideality factor of a reverse biased Schottky contact to be extracted from a single set of I-V measurements. A theo- retical derivation of the proposed approach was presented and a series of validation tests were then performed. The results show that the pro- posed method is capable of extracting reliable estimates of the contact parameters even in the presence of experimental noise.
文摘This paper presents a low-phase-noise LC voltage-controlled oscillator (LC-VCO) with top resistive biasing in subthreshold region. The subthreshold LC-VCO has low-power and low-phase-noise due to its high transconductance efficiency and low gate bias condition. The top resistive biasing has more benefit with the feature of phase noise than MOS current source since it can support the low-noise characteristics and large output swing. The LC-VCO designed in 130-nm CMOS process with 0.7-V supply voltage achieves phase noise of -116 dBc/Hz at 200 kHz offset with tuning range of 398 MHz to 408 MHz covering medical implant communication service (MICS) band.
基金Supported by the National Key Technological Program of China (No.2008ZX01035-001)the National Natural Sci-ence Foundation of China (No.60870001)TNList Cross-discipline Fundation
文摘As semiconductor manufacturing migrates to more advanced technology nodes, accelerated aging effect for nanoscale devices poses as a key challenge for designers to find countermeasures that effectively mitigate the degradation and prolong system's lifetime. Negative Bias Temperature Instability (NBTI) is emerging as one of the major reliability concerns. Two software tools for NBTI analyzing are proposed in this paper, one for transistor-level, and the other for gate-level. The transistor-level can be used to estimate the delay degradation due to NBTI effect very accurately, while the gate-level can be used for repeat analysis in circuit optimization because of its fast computing speed.
文摘随着电力负荷快速增长,电力系统的故障电流水平持续上升,甚至超出了现有断路器的开断能力;为有效限制故障电流,超导故障限流器(superconducting fault current limiter,SFCL)逐渐投入应用。SFCL在正常运行时呈现零阻抗,故障发生后迅速转为高阻抗,可作为配合断路器开断的理想选择,提高电力系统的运行安全性。介绍了一种磁偏置型超导故障限流器(magneto-biased superconducting fault current limiter,MBSFCL),提出了考虑短路电流非周期分量影响的MBSFCL设计方法,对于MBSFCL的制造具有一定的指导意义。通过搭建仿真模型,验证了所提出方法的可行性,并对MBSFCL的限流特性进行了深入分析,讨论了不同非周期分量对断路器的开断影响,以及MBSFCL中电感、电阻参数变化对短路电流及其分量的限流效果影响。分析结果表明,在所提出MBSFCL设计方法中必须考虑非周期分量,且MBSFCL的电阻参数变化对短路电流的抑制效果更为显著。
