In this paper, electrical energy quality and its indices in ship electric networks are introduced, especially the meaning of electrical energy quality terms in voltage and active and reactive power distribution indice...In this paper, electrical energy quality and its indices in ship electric networks are introduced, especially the meaning of electrical energy quality terms in voltage and active and reactive power distribution indices. Then methods of measurement of marine electrical energy indices are introduced in details and a microprocessor measurement-diagnosis system with the function of measurement and control is designed. Afterwards, estimation and control of electrical power quality of marine electrical power networks are introduced. And finally, according to the existing method of measurement and control of electrical power quality in ship power networks, the improvement of relative method is proposed.展开更多
With the increasing complexity of industrial application, an embedded control system (ECS) requires processing a number of hard real-time tasks and needs fault-tolerance to assure high reliability. Considering the cha...With the increasing complexity of industrial application, an embedded control system (ECS) requires processing a number of hard real-time tasks and needs fault-tolerance to assure high reliability. Considering the characteristics of real-time tasks in ECS, an integrated algorithm is proposed to schedule real-time tasks and to guarantee that all real-time tasks are completed before their deadlines even in the presence of faults. Based on the nonpreemptive critical-section protocol (NCSP), this paper analyzes the blocking time introduced by resource conflicts of relevancy tasks in fault-tolerant multiprocessor systems. An extended schedulability condition is presented to check the assignment feasibility of a given task to a processor. A primary/backup approach and on-line replacement of failed processors are used to tolerate processor failures. The analysis reveals that the integrated algorithm bounds the blocking time, requires limited overhead on the number of processors, and still assures good processor utilization. This is also demonstrated by simulation results. Both analysis and simulation show the effectiveness of the proposed algorithm in ECS.展开更多
Compared to finite impulse response (FIR) filters, infinite impulse response (IIR) filters can match the system better with much fewer coefficients, and hence the computation load is saved and the performance improves...Compared to finite impulse response (FIR) filters, infinite impulse response (IIR) filters can match the system better with much fewer coefficients, and hence the computation load is saved and the performance improves. Therefore, it is attractive to use IIR filters instead of FIR filters in active noise control (ANC). However, filtered-U LMS (FULMS) algorithm, the IIR filter-based algorithm commonly used so far cannot ensure global convergence. A new IIR filter based adaptive algorithm, which can ensure global convergence with computation load only slightly increasing, is proposed in this paper. The new algorithm is called as filtered-e LMS algorithm since the error signal of which need to be filtered. Simulation results show that the FELMS algorithm presents better performance than the FULMS algorithm.展开更多
文摘In this paper, electrical energy quality and its indices in ship electric networks are introduced, especially the meaning of electrical energy quality terms in voltage and active and reactive power distribution indices. Then methods of measurement of marine electrical energy indices are introduced in details and a microprocessor measurement-diagnosis system with the function of measurement and control is designed. Afterwards, estimation and control of electrical power quality of marine electrical power networks are introduced. And finally, according to the existing method of measurement and control of electrical power quality in ship power networks, the improvement of relative method is proposed.
文摘With the increasing complexity of industrial application, an embedded control system (ECS) requires processing a number of hard real-time tasks and needs fault-tolerance to assure high reliability. Considering the characteristics of real-time tasks in ECS, an integrated algorithm is proposed to schedule real-time tasks and to guarantee that all real-time tasks are completed before their deadlines even in the presence of faults. Based on the nonpreemptive critical-section protocol (NCSP), this paper analyzes the blocking time introduced by resource conflicts of relevancy tasks in fault-tolerant multiprocessor systems. An extended schedulability condition is presented to check the assignment feasibility of a given task to a processor. A primary/backup approach and on-line replacement of failed processors are used to tolerate processor failures. The analysis reveals that the integrated algorithm bounds the blocking time, requires limited overhead on the number of processors, and still assures good processor utilization. This is also demonstrated by simulation results. Both analysis and simulation show the effectiveness of the proposed algorithm in ECS.
基金This work was supported by the National High Technology Research and Development of China(863 Program:2002AA412410).
文摘Compared to finite impulse response (FIR) filters, infinite impulse response (IIR) filters can match the system better with much fewer coefficients, and hence the computation load is saved and the performance improves. Therefore, it is attractive to use IIR filters instead of FIR filters in active noise control (ANC). However, filtered-U LMS (FULMS) algorithm, the IIR filter-based algorithm commonly used so far cannot ensure global convergence. A new IIR filter based adaptive algorithm, which can ensure global convergence with computation load only slightly increasing, is proposed in this paper. The new algorithm is called as filtered-e LMS algorithm since the error signal of which need to be filtered. Simulation results show that the FELMS algorithm presents better performance than the FULMS algorithm.
