Advanced Materials Research Vols. 199-200

Abstract: In this paper, an expanded Elman network is applied to forecast the vehicle dynamic characteristic and a one step predictive control is also put into use to reinforce its handling stability. The combined control strategy is established based on the conception of the distribution of the driving force between the front and rear driving axles that can be easily achieved in an EV. Moreover, in this research, the distribution proportion of longitudinal driving force defining as a parameter is introduced and the control method of vehicle stability with the aid of the distribution proportion between axles is investigated．Simu1ations have been carried out and the results indicate that the proposed control strategies achieve smooth control effects and rapid target tracking response. This method can be easily applied to the vehicles that are driven by motors, and is capable of improving the lateral dynamic stability of vehicles in most conditions．

Abstract: The thin-layered method (TLM) is very efficient to the wave propagation in layered ground and boundary element method (BEM) is very precise to solve infinite domain problems. In order to study the isolation vibration effectiveness of non-uniform three-dimensional (3D) layered ground wave impeding block (WIB), this paper is accomplished with the aid of a 3D semi-analytical BEM based on TLM, on which the Green’s function is regarded as fundamental solution of a stratified half-space. Then the active isolation effectiveness by WIB is studied under horizontal-rocking coupled loading in elastic half-space in the upper stiff-layer and lower soft-layer. The results show that the foundation of the stratification parameter and the characteristics of non-uniform have significant influence on the vibration isolation effect of the WIB, and the isolation vibration effectiveness of lower soft-layer is better than the upper stiff-layer.

Abstract: The gas heater, reliable as it is, is nevertheless slow in getting started, and is one of the low-efficiency energy consumption equipments adopting the indirect heating by the intermediate heat carrier medium. Apparently, the form of heat transfer process of the intermediate heat carrier medium, i.e. the flow field organization in the large capacity cylinder, is one of the key elements that can improve the thermal efficiency of gas heater. Experimental investigation and analysis of the flow condition and temperature distribution between the water and ethylene glycol in the cylinder were carried out. Based on the investigations on medium selection and heater’s integral structure and combining with the engineering practical needs, effective measures to improve the efficiency of gas heaters have been brought forward in this article and the technology has got itself the China patents.

Abstract: Thermal contact resistance is one of key technologies for heat transfer of high power light emitting diodes (LED) packaging. In this paper, based on the resistance network model of LED packaging, a 3-D finite element simulation model (FEM) is established and thermal transient testing experiments are also performed by Thermal Transient tester (T3Ster). Experiment date indicates thermal contact resistance for 48% of the total thermal resistance. The thermal interface material (TIM) layer of high power LED packaging is studied to analysis thermal contact resistance which impacts on thermal performance of LED packaging. The total thermal resistance and the thermal resistance of TIM layer are separately calculated from simulation and experiment. To the resistance of TIM layer, the result of experiment is only a 1% error compared to the result of FEM simulation. Therefore, The FEM simulation and experiment are mutually validated. In order to thoroughly study on thermal contact resistance, based on the principle of structure function, thermal resistance of three different types of TIM layer between metal core printed circuit board (MCPCB) and aluminum heat sink are measured and compared. Experiment results indicate that the quality of interface affects the thermal contact resistance to a great extent.

Abstract: This paper measures the LED thermal resistance characteristic by thermal transient tester (T3Ster) obtained the cumulative structure functions curve and differential structure functions curve. The actual K factor and optical power are obtained by testingⅠ. The thermal resistance characteristic of each layer for LED structure are analyzed by testingⅡ in different cases. The experimental results show that the bonding method and the heat sink size have tremendous influence on the LED thermal resistance’s reduce, and the contact thermal resistance takes up a great proportion in LED total thermal resistance. The contact thermal resistance may reduce by pressure on interface and by a change of the attach material and the roughness of interface.

Abstract: The knowledge of temperature field of oil-filled transformer directly related to the judgment of overheated fault. There are mainly heat exchange, convection and their coupling in the transformer. Lot of traditional methods are not enough direct-viewing, and ignore the actual situation. The geometrical model of the transformer first modeled by Solidworks, and then ANSYS CFX is used to simulate the temperature field and flow field. Get a set of computer experiment result which can be reference. This computer experiment bring forth the method and effect of the simulate using that software, and make a foundation for the research of transformer overheated fault.

Abstract: The simulation calculation on the temperature field of the disc brake system on high-speed trains under the working condition of constant speed at 50Km/h is made. A steady-state calculation model is established according to the actual geometric size of a brake disc and a brake pad, and the analog calculation and simulation on the temperature field of the brake disc and the brake pad by using the large-scale nonlinear finite element software ABAQUS are carried out. The distribution rules of the temperature field of the brake disc and the brake pad under the working condition of constant speed are made known. The surface temperature of the brake disc at friction radius is the highest, with a band distribution for temperature. There exists a temperature flex point in the direction of thickness, of which the thickness occupies 15% of that of the brake disc; due to the small volume of the brake pad, the temperature gradient of the whole brake pad is not sharp, and larger temperature gradient occurs only on the contact surface.

Abstract: It is key to improve the machining efficiency of finishing lapping machine to restrain the vibration that raise with work speed. The vibration amplitude is influenced by the excitation force of unbalanced crank-rocker mechanism and the anti-vibration performance of guide. Following improving schemes as adding counterweight to crank-rocker mechanism, adopting the light material motion components and enhancing the anti-vibration performance of guide are proposed based on theoretical and experimental studies. The improving schemes are verified by the experiment.

Abstract: In this paper, an investigation on structure function of LED for thermal resistance testing is presented. LED was placed on aluminum plate in different locations. Four group experiments were applied to determine thermal resistance of LED. A simple and effective solution is proposed and discussed on the spreading resistance. The experimental results show the relationship between junction temperature and different locations.

Abstract: In this paper, the simulation software was applied to evaluate a hybrid ventilated combined mechanical and naturally ventilated (atrium area to be naturally ventilated) building. In order to understand the impact of the usage of natural ventilation on thermal comfort in atrium, we utilized TAS to simulate the air temperature and air velocity distribution for the atrium. A modeled three-storey commercial office building was used as the main subject of this analysis. To determine the thermal comfort level of the central atrium, Parameters will be set in such a way that the full height windows will be 100% open. Results were tabularized to determine and analysis the output of the simulation. Recommendations will be then given based on the output performance of the building.