Advanced Materials Research Vols. 211-212

Abstract: The QoS requirement of a connection is given as a set of constraints, which can be link constraints, path constraints, or tree constraints. A feasible path (tree) is one that has sufficient residual resources to satisfy the QoS constraints of a connection. In this solution some complicated constraint are relaxed and the primal problem is decomposed into several sub problems. Primal feasible solutions are obtained by some heuristics and a link set adjusting method is proposed by the aggregate flow on links. In computational experiments, the proposed algorithm determines solutions that are within a few percent of an optimal solution with 30 nodes in the QoS model. In terms of performance, our solution has more significant improvement than simple heuristics. The improvement on the total revenue can reach 12% on the average in the QoS model. The improvement of heuristics 2 in the QoS model on the total revenue can reach 8% on the average.

Abstract: In wireless cellular network, users will share the time-slots channel and bandwidth with voice users. With the characteristic of dynamic slot allocation, some time slots can be allocated to one single user. How to choose the slot allocation methodology is a significant problem when considering the system revenue and users’ satisfaction. A new model based on improvement of Markov Decision Process) is developed that can combines the original maximum system revenue model and the call blocking constraints, and will find out the optimal policy of time slots allocation. The experiment result shows that the new algorithm and model is efficient in the channel assignment area of wireless networks.

Abstract: Methods of tribo-system health state recognition and wear residual lifetime prediction are proposed based on wear failure mechanism, many uncertain influence factors also being taken into consideration. It mainly deals such engineering problems as tribological behavior measurement, friction pair surface testing, experiment data collection and management, feature extraction and health state recognition, and so on. It outlines the basic frame of the application of PHM technology in the tribo-system.

Abstract: This paper presents an approach to analyze accelerated life testing (ALT) data involving two failure modes. The approach first transforms the ALT dataset into two new datasets that correspond to individual failure modes. Each transformed dataset is modeled using a two-step procedure, and the resulted models associated with individual failure modes are combined into a competing risk model. The approach is illustrated using the ALT data of industrial heaters from the literature. The analysis shows that the shape parameter of the life distribution can change with stress level.

Abstract: Crash pulse is an important parameter that can directly reflect the process of vehicle crash. And it is found that there exists an interrelationship between crash pulses and injuries of occupants. In this paper, a method of crash pulse modeling named TESW was adopted to simplify the real crash pulse with several characteristic parameters and then 37 groups characteristic parameters were obtained from 37 crash pulses of full-scale frontal tests, subsequently correlation analysis of crash pulse of body and injury of occupant were performed. And several rules that how these characteristic parameters correlate injuries of occupants were summarized.

Abstract: By means of the complex variable functions, dynamic expension problems on symmetrical mode Ⅲ interface crack were researched. The problems considered can be very facilely transformed into Riemann-Hilbert problem by the measures of self-similar functions, and the general expressions of analytical solutions for the edges of mode Ⅲ symmetrical interface crack subjected to motive variable loadings Px²/t³ and Pt⁴/x³ were obtained by means of self-similar functions, respectively. After those solutions were utilized by superposition theorem, the solutions of arbitrary complex problems could be readily attained.

Abstract: Based on the fuzzy theory and an idea of multidisciplinary design optimization, a fuzzy optimization model of multidisciplinary design is established. Fuzzy constraints are changed by a fuzzy comprehensive evaluation and an amplification-coefficient method. Using collaborative optimization and genetic algorithms, the multidisciplinary fuzzy optimum of planar linkage mechanism is achieved and a four-bar mechanism is given as an example. Two disciplines are involved in the design optimization of mechanism, i.e., kinematics and control. The numerical results indicate that the optimized mechanism not only satisfies the mechanism and control constraints, but also synthesizes approximate optimum value, and lays a foundation for the solution of more complex mechanical system.

Abstract: This paper presents a fault diagnosis method of automobile rear axle based on wavelet packet analysis (WPA) and support vector machine (SVM) classifier. By Fourier transformation we find out the frequency band that can mostly reflect the rear axle failure state and use wavelet packet to decompose and reconstruct the vibration signals of rear axle, then extract each band’s energy and the variance, standard deviation, skewness, kurtosis of the specific frequency band to constitute a feature vector. We use the feature vectors which are come from some pieces of normal and abnormal samples to train support vector machine classifier for obtaining the best classification，at the same time, discuss the optimization of SVM parameters. Application shows that the method is effective in real time fault diagnosis for the automobile rear axle and has a strong anti-interference ability in different working conditions.

Abstract: It is important to develop a new special material to meet the requirement of advanced industry. The BST (Ba_0.8Sr_0.2TiO₃) ceramics doped La₂O₃ and Sm₂O₃ was fabricated by the conventional method, and was tested by X-ray diffraction (XRD), Complex Impedance Testing Instrument, LCR Tester with temperature controlling systems. The results indicate that dielectric property of BST-based ceramics doped 0.05 mol% La₂O₃ and 0.2 mol% Sm₂O₃ simultaneously is the best, and Sm₂O₃ had applications of removing T_c of matrix material to a low temperature and making peak wider. The calcining temperature of samples was 1280 °C.

Abstract: Based on the complexity of surface vibration of diesel engine, the wavelet denoising method is used to process the monitor signal Preliminary. And then several vibration modes are isolated based on EMD method. Finally take the energy of these vibration modes as the input parameters to create neural network for fault diagnosis of diesel engine valve. The method has accomplished the fault diagnosis of the diesel engine merging many methods.