Applied Mechanics and Materials Vols. 490-491

Abstract: In order to estimate the coherent source, a modified multiple signal classification (MUSIC) algorithm is introduced. And a novel arrangement method for the non-uniform linear array by particle swarm optimization (PSO) algorithm is proposed. This method needs merely a signal source whose direction-of-arrival (DOA) has been exactly known. The proposed method has a simple processing and a strong stabilization. It could be applied to optimized arbitrary array configuration. The simulation verifies that the performance of DOA estimation is improved effectively, which has proved the validity of the proposed method.

Abstract: This paper through analysis the relationship between angle of voltage and current, proposes a new distance protection scheme based on double side electric parameters. This method can directly locate the fault accurately. It can regardless the influence of series compensation installation location and MOV non-linear, and it can overcomes the overreach problem for external faults. So greatly improves the reliability of series compensated line distance protection. The simulating results show the validity and adaptability of the protection principle proposed.

Abstract: In the static voltage stability analysis, we usually use the vertex of the P-U curve as the critical point of the voltage stability. This method can not reveal the problem of the physical essence of the voltage stability and the instability mechanism. We must adopt the dynamic analysis method to analyze the voltage stability from the dynamic factors. This paper discuss the small disturbance analysis method and the continuation algorithm analysis method of the dynamic analysis method, then research the mechanism of voltage collapse and the results of the dynamic analysis. At the same time, a load model and elements of the system dynamic model suitable for the voltage stability analysis is the key and difficult point of the voltage stability research.

Abstract: Sequential turbocharging and inlet/exhaust bypass (STC-CAB) were composited to used on diesel engine, which can expand engine running area in part load and optimize the matching of turbocharger and diesel engine. The simulation was studied based on GT-POWER software in order to investigate the engine performance difference caused by stc-cab system. The simulation results showed that STC-CAB system can make the compressor away from surge area and expand diesel engine running area, improve the performance of torque in low load.

Abstract: Based on the Putaohua groups in Yushulin oil field, and through the statiscics and analyses, weve found that the reservoir property of this area is in the range of specially low permeability level. So due to the low porosity and permeability, its necessary to do some reaearch on the parameters calculation method.This papers analysed the relationships between the physical property parameters such as porosity, permeability, shale content and the well logging responses such as AC, SP, GR, then we built the distribution rules histograms of each physical property parameter. And we got the distribution situations of the parameters of the oil groups. Through the multiple regression, we built the relationship formulas between the reservoir property parameters and the well logging responses by using the core analysis data of 53 test wells. Afetr comparing the parameters of calculation and the core analysis data, we found that the deviation is small, which meets the production requires of oil field.

Abstract: The article uses the cosine function and Euclidean distance function to optimize the traditional GM (1, 1) model. The cosine function processing the raw data columns, which could enhance the smoothness of the original series, and strengthen the general trend of the original series as well, effectively eliminate the shock interference of disturbed system. The principle of minimum Euclidean distance used to optimize the response function to determine the constants C, which could make better use of the original information. The improved model is applied to the tertiary industry in Beijing load forecasting, the results show that the improved model has higher prediction accuracy, and the improved model used to predict the next three years’ electricity consumption of tertiary industry in Beijing.

Abstract: The Darcy linear equation has been widely used to describe the fluid flow in porous media. It is inaccurately used to describe the flow through preferential flowing paths which exert important influence on the performance of waterflooding reservoir. In this paper, the following two problems have been studied: (1) flow law in preferential flowing paths generated by water flooding; (2) sound nonlinear mathematical model considering special internal and external boundary conditions. The greater the permeability in porous medium becomes, the easier fluid can flow. Meanwhile the flow mechanism would change correspondingly as well. Exact solution of the nonlinear model is obtained analytically by integration. It is shown that in preferential flowing channels the flow velocity and the pressure gradient are a nonlinear relationship which is different from the traditional Darcy theory described as a straight line. Finally, the seepage characteristics of nonlinear flow and its influence are determined by analyzing the pressure gradient curve and velocity distribution between the observation point and the target well. Keywords: Preferential flowing paths; Non-linear model; Forchheimer equation; Integration method; Pressure gradient.

Abstract: This paper introduces the virtual maintenance technology, expounds the present situation of agricultural vehicle maintenance and the necessity of virtual maintenance application in vehicle maintenance, and discusses the application of virtual maintenance technology in agriculture vehicle maintenance. Finally the suggestions used on virtual agricultural vehicle maintenance in the future are put forward.

Abstract: Due to the influence of low temperature, high speed and agitation in the pipeline, gas hydrate can be easily formed and blocks the pipeline. If the non-complete blockage pipeline segments are accurately detected with the number, location, length and magnitude of the blocked segments identified, the proper pigging operation scheme can be made to reduce the risk of complete blockage in the pipeline. The authors put forward that by using mass pulse launched at the pipeline inlet, the characteristic data of pipeline blockages can be identified through its propagation characteristics in multiple non-completely blocked natural gas pipeline segments. In this paper, the mathematical model of gas transient flow in a pipeline with multiple blockages is established, and pulse propagation in the blocked pipeline is simulated by using time splitting algorithms and TVD / Godunov mixed format. Under the conditions of maintaining the valve open at the end of the pipeline, the history curve of pressure fluctuation at the pipeline inlet is analyzed to dynamically identify the number of segments blocked in natural gas pipeline, blockage positions, blockage length, and blocking magnitude of multiple blockages.

Abstract: The availability of multi-fields simulation and rapid design is at core of a competitive design ability of chamber systems for IC (integrated Circuit) manufacturing. A computer system is required to provide rapid response for both new designs and processing validations, so programming the design and simulation procedure is necessary. However, some steps of the design and simulation procedure are not clear in the initial design stage in many cases. They only can be decided when part of the structure is visible, particularly when novel structures or new working principles are used. The use of agents is one way to collect information that is required but cannot be pre-programmed in computers. This paper presents a generic method to configure agents, including an analysis framework using a six stage design process, the agent analysis for general design and simulation process, the procedures of design and processing simulation of chambers, the configuration of agents, and finally the conclusion and further works. This paper contributes a generic agent design method.