Active filters are used to eliminate current harmonics near nonlinear loads. This paper presents a new method for the evaluation of the current that should be injected by the active filter in order to eliminate harmon...
详细信息
Active filters are used to eliminate current harmonics near nonlinear loads. This paper presents a new method for the evaluation of the current that should be injected by the active filter in order to eliminate harmonics. The method proposed is based on the Synchronous Reference Frame method and explores the fact that the performance of the active filter depends on the speed of the system that determines the rotating reference frame, but doesn't depend on its position. Compared with other methods, this method presents some advantages, due to its simplicity and its rudeness to perturbations on the ac network. Normally active filters have poor performances under non symmetrical and non-sinusoidal voltage conditions. The method proposed in this paper presents good response in presence of harmonics on the ac mains voltages and in presence of imbalance.
Austenitic stainless steel transforms from austenitic crystal structure to martensitic crystal structure after applying strain or stress. Because martensitic crystal structures have magnetization, strain evaluation an...
Austenitic stainless steel transforms from austenitic crystal structure to martensitic crystal structure after applying strain or stress. Because martensitic crystal structures have magnetization, strain evaluation and fatigue evaluation can be performed by measuring magnetic properties. This paper describes the measurement of leakage magnetic flux density of remanent magnetization for the strain evaluation and the fatigue evaluation by a typical Hall element sensor for SUS 304 and SUS 304L and by a high‐sensitivity thin‐film flux‐gate magnetic sensor for SUS 316 and SUS 316L.
Spectral estimation is important in many fields including astronomy, meteorology, seismology, communications, economics, speech analysis, medical imaging, radar, sonar, and underwater acoustics. Most existing spectral...
ISBN:
(数字)9781598290011
Spectral estimation is important in many fields including astronomy, meteorology, seismology, communications, economics, speech analysis, medical imaging, radar, sonar, and underwater acoustics. Most existing spectral estimation algorithms are devised for uniformly sampled complete-data sequences. However, the spectral estimation for data sequences with missing samples is also important in many applications ranging from astronomical time series analysis to synthetic aperture radar imaging with angular diversity. For spectral estimation in the missing-data case, the challenge is how to extend the existing spectral estimation techniques to deal with these missing-data samples. Recently, nonparametric adaptive filtering based techniques have been developed successfully for various missing-data problems. Collectively, these algorithms provide a comprehensive toolset for the missing-data problem based exclusively on the nonparametric adaptive filter-bank approaches, which are robust and accurate, and can provide high resolution and low sidelobes. In this book, we present these algorithms for both one-dimensional and two-dimensional spectral estimation problems.
This article presents an analysis of how pulses in the long two-conductor coupled lines with conductor screened interact mutually. The interaction of pulses appears in those places of the line, where there is a change...
详细信息
This article presents an analysis of how pulses in the long two-conductor coupled lines with conductor screened interact mutually. The interaction of pulses appears in those places of the line, where there is a change of wave impedance causing a change in reflection coefficient for pulses moving along the line. An exemplary analysis is performed for a homogenous lossless line at its starting and terminal points. The results of analysis are analytical expressions describing quantitative interactions of pulses. The expressions are verified both by computer simulation and by measurements of the real line. There has been performed the analysis of influence of the resistances with which the terminal points of the line are loaded onto the amplitude value of the pulses registered at the starting point of the line. The new method and the new system of measurements of pulses have been proposed that minimize the interaction of pulses at the starting point of the line, disadvantageous for the process of fault location by using pulse method.
The paper presents regulation characteristics that fulfill the requirements of highest possible efficiency and strongly reduced torque ripple level. For switched reluctance motors it is not so simple and obvious, beca...
详细信息
The paper presents regulation characteristics that fulfill the requirements of highest possible efficiency and strongly reduced torque ripple level. For switched reluctance motors it is not so simple and obvious, because the regulation characteristics depend on three variables: phase voltage, switch-on and switch-off angles. For this reason in a steady state the same operation point (Tl, ω) of the mechanical characteristic is attainable for quite different values of those control parameters. So there is a field for quasi-optimal operation and the choice of the coresponding control parameters is the main subject of this work. The paper presents also the method to determine these quasi-optimal control characteristics from simple tests or from computations based on presented simple mathematical model.
The concept of intraepithelial neoplasm (IEN) as a near-obligate precursor of cancers has generated opportunities to examine drug or device intervention strategies that may reverse or retard the sometimes lengthy proc...
The concept of intraepithelial neoplasm (IEN) as a near-obligate precursor of cancers has generated opportunities to examine drug or device intervention strategies that may reverse or retard the sometimes lengthy process of carcinogenesis. Chemopreventive agents with high therapeutic indices, well-monitored for efficacy and safety, are greatly needed, as is development of less invasive or minimally disruptive visualization and assessment methods to safely screen nominally healthy but at-risk patients, often for extended periods of time and at repeated intervals. Imaging devices, alone or in combination with anticancer drugs, may also provide novel interventions to treat or prevent precancer.
The objective of this research is to determine a near optimal fuel efficient control strategy for an electric propulsion space vehicle to attain a predefined velocity at the target. The control strategy is represented...
详细信息
ISBN:
(纸本)1889335339
The objective of this research is to determine a near optimal fuel efficient control strategy for an electric propulsion space vehicle to attain a predefined velocity at the target. The control strategy is represented as a chromosome and micro genetic algorithms are used to find the best solution. The control strategy uses me space vehicle's reverse thrust and the sling effect caused by the Sun. Copyright - World Automation Congress (WAC) 2006.
A linear time-varying filter with the characteristic of variable bandwidth is proposed for noise reduction of signals with time-varying bandwidth and decomposition of multicomponent signals into components. The propos...
详细信息
In the paper the problem of disturbance attenuation performance in single-loop control system is investigated. Modified MV control strategy with bounded control variance is used as benchmark for both LQG and classical...
详细信息
ISBN:
(纸本)1424401704;9781424401703
In the paper the problem of disturbance attenuation performance in single-loop control system is investigated. Modified MV control strategy with bounded control variance is used as benchmark for both LQG and classically and optimally tuned PID-type controllers. Certain time and frequency domain functions are then examined to further assess the control performance in terms of robustness. It has been shown that as long as the system to be controlled is delay-free, and there is no extreme demand on performance, simple lag-delay system model along with optimally tuned PID control algorithm provides control quality similar to that of LQG controlled original system assuming the same bound on control signal variance. Although the classical performance measure based on substitute delay indicates then almost optimal performance, there is still room for additional improvement that can be attained using both PID and LQG controllers and more sophisticated original delay-free model. The price paid is much larger control variance. It is interesting to note that while LQG systems remain robust this is not longer valid for PID controllers
暂无评论