对深空网天线组阵中的几种信号相关算法作简要介绍,重点研究无需形成矩阵的幂的方法——Matrix-Free Power Method。通过理论分析,提出一种改进算法,即基于归一化权的Matrix-Free Power Method。理论计算和软件仿真结果均表明,基于归一...对深空网天线组阵中的几种信号相关算法作简要介绍,重点研究无需形成矩阵的幂的方法——Matrix-Free Power Method。通过理论分析,提出一种改进算法,即基于归一化权的Matrix-Free Power Method。理论计算和软件仿真结果均表明,基于归一化权的Matrix-Free Power Method信噪比合成性能略优于原Matrix-Free Power Method。展开更多
The main drawback of current ECG systems is the location-specific nature of the systems due to the use of fixed/wired applications. That is why there is a critical need to improve the current ECG systems to achieve ex...The main drawback of current ECG systems is the location-specific nature of the systems due to the use of fixed/wired applications. That is why there is a critical need to improve the current ECG systems to achieve extended patient’s mobility and to cover security handling. With this in mind, Compressed Sensing (CS) procedure and the collaboration of Sensing Matrix Selection (SMS) approach are used to provide a robust ultra-low-power approach for normal and abnormal ECG signals. Our simulation results based on two proposed algorithms illustrate 25% decrease in sampling-rate and a good level of quality for the degree of incoherence between the random measurement and sparsity matrices. The simulation results also confirm that the Binary Toeplitz Matrix (BTM) provides the best compression performance with the highest energy efficiency for random sensing matrix.展开更多
The thermal resistance matrix including self-heating thermal resistance and thermal coupling resistance is presented to describe the thermal effects of multi-finger power heterojunction bipolar transistors. The depend...The thermal resistance matrix including self-heating thermal resistance and thermal coupling resistance is presented to describe the thermal effects of multi-finger power heterojunction bipolar transistors. The dependence of thermal resistance matrix on finger spacing is also investigated. It is shown that both self-heating thermal resistance and thermal coupling resistance are lowered by increasing the finger spacing, in which the downward dissipated heat path is widened and the heat flow from adjacent fingers is effectively suppressed. The decrease of self-heating thermal resistance and thermal coupling resistance is helpful for improving the thermal stability of power devices. Furthermore, with the aid of the thermal resistance matrix a 10-finger power heterojunction bipolar transistor （HBT） with non-uniform finger spacing is designed for high thermal stability. The optimized structure can effectively lower the peak temperature while maintaining a uniformity of the temperature profile at various biases and thus the device effectively may operate at a higher power level.展开更多
The paper demonstrates the possibility to enhance the damping of inter-area oscillations using Wide Area Measurement (WAM) based adaptive supervisory controller (ASC) which considers the wide-area signal transmission ...The paper demonstrates the possibility to enhance the damping of inter-area oscillations using Wide Area Measurement (WAM) based adaptive supervisory controller (ASC) which considers the wide-area signal transmission delays. The paper uses an LMI-based iterative nonlinear optimization algorithm to establish a method of designing state-feedback controllers for power systems with a time-varying delay. This method is based on the delay-dependent stabilization conditions obtained by the improved free weighting matrix (IFWM) approach. In the stabilization conditions, the upper bound of feedback signal’s transmission delays is taken into consideration. Combining theoriesof state feedback control and state observer, the ASC is designed and time-delay output feedback robust controller is realized for power system. The ASC uses the input information from Phase Measurement Units (PMUs) in the system and dispatches supplementary control signals to the available local controllers. The design of the ASC is explained in detail and its performance validated by time domain simulations on a New England test power system (NETPS).展开更多
文摘对深空网天线组阵中的几种信号相关算法作简要介绍,重点研究无需形成矩阵的幂的方法——Matrix-Free Power Method。通过理论分析,提出一种改进算法,即基于归一化权的Matrix-Free Power Method。理论计算和软件仿真结果均表明,基于归一化权的Matrix-Free Power Method信噪比合成性能略优于原Matrix-Free Power Method。
文摘The main drawback of current ECG systems is the location-specific nature of the systems due to the use of fixed/wired applications. That is why there is a critical need to improve the current ECG systems to achieve extended patient’s mobility and to cover security handling. With this in mind, Compressed Sensing (CS) procedure and the collaboration of Sensing Matrix Selection (SMS) approach are used to provide a robust ultra-low-power approach for normal and abnormal ECG signals. Our simulation results based on two proposed algorithms illustrate 25% decrease in sampling-rate and a good level of quality for the degree of incoherence between the random measurement and sparsity matrices. The simulation results also confirm that the Binary Toeplitz Matrix (BTM) provides the best compression performance with the highest energy efficiency for random sensing matrix.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61006059, 60776051, and 61006044)the Beijing Municipal Natural Science Foundation of China (Grant No. 4082007)+3 种基金the Beijing Municipal Education Committee of China (Grant Nos. KM200710005015 and KM200910005001)the Beijing Municipal Trans-century Talent Project of China (Grant No. 67002013200301)the Beijing Innovatory Talent Training Program of China (Grant No. 00200054RA001)the Ph. D. Start Science Foundation of Beijing University of Technology of China (Grant No. X0002013201102)
文摘The thermal resistance matrix including self-heating thermal resistance and thermal coupling resistance is presented to describe the thermal effects of multi-finger power heterojunction bipolar transistors. The dependence of thermal resistance matrix on finger spacing is also investigated. It is shown that both self-heating thermal resistance and thermal coupling resistance are lowered by increasing the finger spacing, in which the downward dissipated heat path is widened and the heat flow from adjacent fingers is effectively suppressed. The decrease of self-heating thermal resistance and thermal coupling resistance is helpful for improving the thermal stability of power devices. Furthermore, with the aid of the thermal resistance matrix a 10-finger power heterojunction bipolar transistor （HBT） with non-uniform finger spacing is designed for high thermal stability. The optimized structure can effectively lower the peak temperature while maintaining a uniformity of the temperature profile at various biases and thus the device effectively may operate at a higher power level.
文摘The paper demonstrates the possibility to enhance the damping of inter-area oscillations using Wide Area Measurement (WAM) based adaptive supervisory controller (ASC) which considers the wide-area signal transmission delays. The paper uses an LMI-based iterative nonlinear optimization algorithm to establish a method of designing state-feedback controllers for power systems with a time-varying delay. This method is based on the delay-dependent stabilization conditions obtained by the improved free weighting matrix (IFWM) approach. In the stabilization conditions, the upper bound of feedback signal’s transmission delays is taken into consideration. Combining theoriesof state feedback control and state observer, the ASC is designed and time-delay output feedback robust controller is realized for power system. The ASC uses the input information from Phase Measurement Units (PMUs) in the system and dispatches supplementary control signals to the available local controllers. The design of the ASC is explained in detail and its performance validated by time domain simulations on a New England test power system (NETPS).
