Advanced Materials Research Vols. 490-495

Abstract: In vehicular ad hoc network(VANETs), it is crucial for obtaining more accurate position information which variation rules between “distance-loss” model influence factors and distance measurement error is analyzed. Based on qualitative analysis of “distance-loss” model, field experimental scene and scheme are proposed. Using experimental sample data, the relation of environmental factor and shelter factor and distance measurement error is studied quantitatively. The experimental results show that distance measurement performance of optimized “distance-loss” model is significantly improved, and 6.7% is the largest reduction proportion of distance measurement error.

Abstract: When different types and extent of faults occurs at transformer winding, the energy of the signals in different frequency bands will change. So it can calculate the characteristic energy of different response signals at different states to determine whether the winding failure. The transformer fault diagnosis method based on FRA and characteristic energy extraction is presented, the maximum cross-correlation between the signal and the wavelet was taken as criterion to choose the wavelet. The method is verified by test. Experimental results show that this method can diagnose winding fault type and extent effectively, and improve the sensitivity of fault diagnosis.

Abstract: To carry out electronic control EGR strategy in diesel engine the calculation model using GT-POWER is built. The thesis uses simulation software GT-POWER to establish the calculation model of 4JB1 intake system of turbocharged diesel engine with EGR system and the results agree well. According to the simulation results, it can predict the main performance indicators of the diesel engine when it works at the maximum torque condition, which includes A/F, IMEP, Maximum Pressure, and Intake Pressure and so on. Then after controlling the volume of gas by modifying the EGR valve, it can find out the regulation how EGR effects the engine's emissions, torque, power and the inlet temperature of turbo. Referring to the simulation results, it includes from four aspects：EGR can significantly improve the quality of emission gas; NOx and PM have a trade-off relationship; applying higher EGR rate in heavy load can lead to the low torque and power less; the inlet temperature of turbo increases with the augment of EGR rate. In the experiment, the inlet oxygen concentration method is used to determine the EGR rate, and to realize it, the oxygen concentration detection module is also successful designed. Then a close-loop control strategy is proposed based on the EGR rate. It proves it is feasible to guide the ECU programmer development by the simulation results of engine control strategy. It is also can be referred by other engine control systems development.

Abstract: Based on predictive control principle of receding optimization, the infinite time domain “min-max” optimization problems are converted into convex programming problems by Lyapunov stable theory and linear matrix inequality (LMI). The sufficient conditions for the robust stability of the uncertain time-delay system are given. Finally, the simulation results illustrate the effectiveness of the proposed methods.

Abstract: In this paper, the numerical simulation of internal and external flow field of target type impinging stream nozzle by using Fluent software is observed, the effect on nozzle atomization was obtained by simulating the size of nozzle structure（the diameter d of nozzle and distance δ between the target and plate）and pressure P (that is to say the flow velocity). The results show that: the larger the structure size and the pressure of nozzle，the better the effect of nozzle atomization.That it has superiority than the general centrifugal nozzles and can save water quantity.

Abstract: The driving fatigue monitoring system based on tree structure classifier is presented. The realtime fatigue monitoring system is established by training face and eye tree-structure classifiers which consists of many strong classifiers. Each strong classifier choose several weak classifiers by AdoBoost recursive method and each weak classifier is characterized by single Haar-like features. The whole Tree-structure is constructed by clustering branches recursive algorithm. Experiment has shown that the driving fatigue monitoring system based on tree-structure classifiers is very reliable. Introduction

Abstract: A new routing algorithm is proposed for FPGA to improve the increasing transformation cost of pseudo-Boolean Satisfiability algorithm in the routing process, which combined advantages of pseudo-Boolean Satisfiability and geometric routing algorithm. In the routing process, one of geometric routing algorithm-VPR5.0 was chosen firstly for FPGA routing. If not successful, then use pseudo-Boolean Satisfiability algorithm. Technique of static symmetry-breaking is also adding to carry out pretreatment of pseudo-Boolean constraints, detecting and breaking the symmetries in the routing flow. The purpose was to prune search path, and the cost was consequently reduced. Preliminary experiments results show that the hybrid approach can reduce the runtime observably, speed up the solving process, and have no adverse affect on overall program.

Abstract: Error modeling and compensation is the most effective way to reduce thermal errors. In this paper, a novel approach to predict the thermal error of machine tool based on M-RAN is presented, clustering analysis is used to select the temperature variables, and then an easy and economical measurement system is applied to measure the temperature variables and thermal shift of CNC machining center. The thermally induced errors are estimated in real-time using the trained M-RAN network. The proposed approach is verified through error compensation test.

Abstract: The mechanical part was heated to the heat treatment temperature, and the surface color changed with temperature. The infrared radiation thermometer was used to get heating part temperature, and the corresponding color images were taken by the camera at the same time. The program was designed to analyze the images and display the temperature. To decrease the effect of the noise disturbance in the process of image, the combined filter method was used. The relationship between the temperature and image of heating mechanical parts were obtained through digital regression. The analysis and comparison results show that the temperature measurement precision of three primary color is higher than gray’s from 700°C to 1100°C. The three primary colors have more information for image recognition than that of gray image, and are suitable for higher technical requirements.

Abstract: Fractal box dimension is a new method to represent self-similarity and complexity of non-stationary mechanical fault signal. In this paper, we first present the basic conception of fractal and box dimension. Then we propose the algorithm to calculate the box dimension of discrete signal. On the basis of wavelet packet decomposition, we quantitatively analyze the vibration signal under different conditions with fault characteristic by way of box dimension. Experimental results show that the box dimensions are different in evidence because of the difference of fault mechanism. As a successful application, fractal box dimension can be used to recognize the fault pattern of hydraulic pump effectively.