Applied Mechanics and Materials Vols. 444-445

Abstract: The levitation control system is a key technique of the maglev system. Due to the strong non-linear character of the magnetic force, as well as the model uncertainties and external interferences of the maglev system, the Implicit General Predictive Control algorithm, which adjusts the parameters of the control scheme by using the input and output data, is adopted in this article. Taking the single electro-magnet levitation system as the research object, this algorithm not only guarantees the stability of the system, but also suppresses the vibration caused by the flexibility of the track. The advantages of this algorithm include: the superior control capacity, roll over optimization and little dependence on model. The simulation approves the validity of this method.

Abstract: Construction of nuclear power plant steel liner is an important component. The design and lifting is a highly complex technical systems engineering. For a nuclear power plant project in China, the displacement and strength of the grid and the steel liner have been analyzed in the lifting process by computer methods. The results show that the use of lifting truss design has good strength and stiffness, which can achieve the requirements. The steel liner in the lifting process itself is not overstressed and deformed. The lifting process can meet the engineering requirements of the installation accuracy.

Abstract: Applying common surrogate models to problems have numerous output variables is computational expensive, since the number of surrogate models should be constructed equals to the number of output variables. This paper presents an efficient strategy to solve this problem. For that, snapshot Proper Orthogonal Decomposition (POD) is used to extract a few main basis modes from certain number of samples. The predicted result of a large-scale output problem comes from the linear superposition of these basis modes. Common surrogate models just need to predict the coefficients for these basis modes. Through this strategy, The Mach numbers at 36864 points around an airfoil are predicted by just constructing 12 kriging surrogate models. The predicted Mach number distributions fit with the CFD results very well, that proves the efficiency of this strategy.

Abstract: To achieve airworthiness requirements, 90 second certification test is performed to show compliance. Recent development in the application of computer simulation makes it possible to improve aviation safety through aircraft evacuation simulation. The approach can replace the full scale certification demonstration and has attracted extensive interest. Various evacuation models have been developed to simulate evacuation process. This review investigates the modeling theoretical foundation and summaries individual applications in different scenarios. Moreover, a meaningful research field is proposed for further study.

Abstract: Some cracks are observed in a heightening project of a concrete gravity. In order to investigate and solve this problem, the three-dimensional finite element simulation and nonlinear cracking analysis are implemented in this paper to analyze the causes of cracks and their propagation trends. This work is helpful to design the proper crack controlling plans. The research shows that large tensile stress has accumulated during construction, especially after an early air temperature sudden drop in November, the tensile stress increases 3MPa in general on the concrete surface, which exceeds the tensile strength of concrete and causes cracking. Therefore, the crack is the result of both the accumulated temperature stress during construction and temperature sudden drop. The crack will further propagate during another temperature sudden drop, but extended range is limited. If concrete tensile strength is greater than 2.5MPa, the cracks will not penetrate throughout the dam body along the water flow direction.

Abstract: Building finite element model of wind turbine tower, analyzing Static and modal of tower with using finite element analysis software ANSYS .Getting stress distribution, maximum displacement, natural frequencies and modes of vibration by finite element modal analysis of wind turbine tower and analyzing natural frequencies of wind turbine tower to determine whether to cause the tower and the wind wheel drive resonance.

Abstract: As a typical binary classifier, its an inseparable sample problem about the Support Vector Machine (SVM) when processing the classification of the multi-class vehicle models. Since the SVM can not estimate the effect size of the samples classification accurately, and then reduces the classification generalization ability. In this paper, a fuzzy Support Vector Machine (FSVM) classification algorithm is applied to vehicle classification. According to the difference of the contribution which the vehicle characteristics make to the classification, the appropriate degree of membership is given, and the algorithm improves the vehicle models classification ability of the traditional SVM effectively. The experimental results show that the new method, compared with the existing vehicle classification method, is feasible, effective, and with a high classification accuracy

Abstract: Under the action of annual change and sudden drop of air temperature, thermal induced cracking will occur in concrete dam during the operation period. For exploring the temperature control measures for crack prevention, taking a concrete gravity dam section as the research object, sensitivity analyses to the factors which affecting the water-cooling effect are conducted with 3D FEM, some significant suggestions for the water cooling are presented. The results show that, the stresses of the dam surface will decrease to a certain extent after water cooling in the operation period using the cooling water pipe which embedded during construction period, and the cracking risk of the dam will reduce. The study provides a new train of thought for the temperature control and crack prevention of the mass concrete during the operation period.

Abstract: Based on the original unsteady simulation program, the transonic aircraft external store separation was simulated by structured chimera grid approach coupled with a six degree of freedom trajectory code. The chimera grid utilized the hole-map cutting method; the searching efficiency was compared between the stencil walk and inverse map when building interpolation during the procedure. The space format utilized flux difference splitting format FDS based on Roe, moreover adding the min-mod limiter to achieve second order accuracy. The time format utilized the implicit integration and discrete scheme of the Back-Euler method. The three-dimensional trajectory of the store was captured and better fit for the experimental data. The results show that the method is correct and provides a reference for the simulation of the unsteady multi-body separation.

Abstract: This paper summarizes the literature and presents important concepts related to conceptual model verification. Different approaches have been proposed in the literature. These approaches have been introduced as two parts with emphasis on formal techniques. First order logic for structural views and Petri nets for behavioral views are investigated in the search of a practical verification method for conceptual modeling in UML. Then a short assessment of formal verification work for UML will be presented.