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The aerodynamic noise of pantograph is one of the most important noise sources of high speed trains. Therefore, the reduction of the aerodynamic noise of pantograph becomes very important for reducing the total noise level of the high-speed trains. In this paper, the distribution of dipole sound sources at the surface of a single-arm pantograph and the noise radiation from it are predicted numerically...
In recent years, energy consumption of information and communication industry have received more and more attention. But the energy efficient optimization problem of interference-limited system is difficult to solve because it is a non-convex problem. In order to deal with this problem, two sub-optimal algorithms, based on dual theory and differ-concave theory respectively, are proposed in this paper...
A vacuum circuit breaker has advantages of low maintenance cost and high reliability. It reaches the priority in aviation field. This paper focuses on the arc behavior of intermediate-frequency (400, 650, and 800 Hz) vacuum arc in commercial-type vacuum interrupters with axial magnetic field contacts. With high-speed photography and volt-ampere characteristics, three different arc modes were identified:...
The fault-free operation of diesel engine in a normal state is a kind of self-excited vibration, but with the change of its technological states in the operation, the vibration will become much more like a random vibration. All the variable information of these technological states is included in the vibration signals of diesel engines, which can be used to judge the different technological states...
In this paper, the morphological changes of the vacuum arc with the breaking current at the intermediate frequency are observed and the volt-ampere characteristic of the vacuum arc at intermediate frequency is analyzed under transverse magnetic field (TMF). Volt-ampere characteristics of the vacuum arc are divided into three phases: the initial arcing phase, the transitional phase, the current decline...
In order to solve the problem that the fault characteristics of hydraulic pump have ambiguity and signal-to-noise of inspected signals is low, a new method based on characteristics of the energy spectrum of vibration signals combing rough set (RS) and principal component analysis (PCA) algorithm is proposed in this paper. This algorithm processes noise abatement for collected vibration signals by...
Intrusion detection is actually a classification problem of detecting the normal and abnormal data separately. However, the data needed for intrusion detection are very large and complex. In this paper, we solved this problem very well, using SVDD (support vector data description) algorithm, and carried out simulation experiments in the network datasets, got a high detection rate and a low false alarm...
In realistic MIMO communication system, the receiver has usually perfect channel state information (CSI), while the transmitter has only partial channel state information feedback from the receiver for many reasons. This paper analyzes the partial channel state information, and introduces a method of equivalent noise to study the design of precoding with partial CSI. In this paper, based on ZF criterion,...
This paper presents the study of intermediate frequency vacuum arc under an axial magnetic field (AMF). Arc voltage noise at the first current half-cycle is inconspicuous even if the current is not interrupted successfully, it can be attributed to the application of a sufficiently strong AMF provided by the current in a short vacuum gap. The influence of current frequency on peak arc voltage and the...
A flux linkage estimation method for induction motor based on extended Kalman filter theory (EKF) is presented in this paper. In order to improve the accuracy of filtering, genetic algorithm (GA) is introduced to optimize the noise matrix, and also filtering parameters in EKF. Simulation results show that the flux observer with optimized filtering parameter has better estimation accuracy and dynamic...
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