Mechanical Engineering and Materials Science

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Authors: Shi Lin Zhang, He Ping Li, Shu Wu Zhang
Abstract: A BS process involves building a model of the background and extracting regions of the foreground (moving objects) with the assumptions that the camera remains stationary and there exist no movements in the background. Video object extraction is a critical task in multimedia analysis and editing. Normally, the user provides some hints of foreground and background, and then the target object is extracted from the video sequence. In this paper, we propose a object segmentation system that integrates a clustering model with Markov random field-based contour tracking and graph-cut image segmentation. The contour tracking propagates the shape of the target object, whereas the graph-cut refines the shape and improves the accuracy of video segmentation. Experimental results show that our segmentation system is efficient.
Authors: Tao Nie, Wei Qiang Liu
Abstract: To study the effects of wall thickness, rib height and groove width on cooling effect and pressure drop, three dimensional heat transfer of liquid propellant rocket engine with cooling groove is numerically investigated using gas-solid-liquid coupled heat transfer model. The one-dimensional model is adopted to describe the coolant flow and 3D heat transfer model is used to calculate the coupling heat transfer through the wall. In this text, wall thickness, rib height and groove width varied while the groove number is fixed and coolant mass flow rate remains constant. When liner material is QZr0.2 alloy, we find the optimal design point of the aspect ratio. Moreover, a fitting function of the optimal aspect ratio is acquired. The biggest error of the fitting function is 3.3% compared with numerical results.
Authors: Yu Ying Zhu, Qiang Li, Yun Hua He, Ge Wang, Xing Hua Wang
Abstract: The Ti50Fe22Ni22Sn6 amorphous powder was prepared by mechanical alloying with a high-energy planetary ball mill. Crystallization kinetics of the milled amorphous powders was investigated by DSC. Thermal analysis showed that when the heating rate increasing from 10K/min to 40K/min, the super-cooled liquid region of milled amorphous alloy increased from 93K to 110K. On the basis of the obtained DSC curves, the characteristic temperatures of the amorphous powders could be measured. The equations of Kissinger and Ozawa were used to calculate the crystallization activation energies of the milled amorphous alloy for comparing. The activation energy for the glass transition Eg had the maximum values of 650KJ/mol and 629KJ/mol calculated from Kissinger and Ozawa, respectively. In addition, the second crystallization process had a higher activation energy value comparing with the others crystallization events.
Authors: Hui Ying Tang, De Quan Shi, Yong Jun Zhao, Da Yong Li, Xu Dong Shi, Zhi Wei Gao
Abstract: In this paper, several methods for testing the filling capacity including mechanical test method, vacuum test method, electrometric method, high-speed photography method and X-ray observation method were reviewed, and they can be divided into two classes, namely traditional test method and new test method based on computer. The principles and measurement process of theses methods were summarily described. Through further analysis and comparison, their merits and limitations were indicated respectively. Also, their applications in measuring filling capacity of liquid alloys were exemplified. Finally, it is thought that the development and application of computer technology will benefit to the accuracy improvement of filling capacity.
Authors: Dong Mei Huang, Guo Jun Zhang, Song Xin Shi
Abstract: The Facility layout of flexible manufacturing workshop is designed under process principle, which is suitable for medium and small batch production.However, large WIP is produced under this facility layout model, and the material transport is relatively disorderly, the production cost is caused very high. Aiming on the problem, the facility layout with variety of materials is researched, and the mathematical model of lowest logistics cost is established with the total logistics cost as the objective function. Finally, according to the workshop equipment layout optimization process, the simulation mode in unit is established with the computer simulation software eM-Plant, and the logistics cost is optimized and compared with the initial result.
Authors: Xiao Hua Song, Dong Xiao Niu, Cai Qin Ye, Dong Liang Lu
Abstract: Power distribution engineering plays an important role in power system, whose construction quality directly impacts the investment income, social and environmental benefits. This paper firstly analyzed the necessity of quality management in power distribution engineering, and then introduced the application of total quality management to the quality management in power distribution engineering. Finally, by combining the basic points of TQM, applying the PDCA cycle and controlling the factors affecting quality management, this article built a basic system model for quality management in power distribution engineering.
Authors: A. Vatani Oskouei, F. Kiakojouri
Abstract: In this study, for behavior of steel plate which subjected to uniform blast loading the general purpose finite element software ABAQUS, was used. The aim of this paper is to recognize the effect of stiffener configurations, boundary conditions, mesh dependency, load patterns, geometry of plates and damping on dynamic response of the plates. Special emphasis is focused on the evolution of mid-point displacements. The results show that stiffener configuration and boundary conditions have a significant influence on the response, while the effects of damping and load pattern on maximum response are negligible. The results obtained allow an insight into the effect of stiffener configurations and other parameters on the response of the plates under uniform blast loading.
Authors: Hai Bo Lu, Wei Qiang Liu
Abstract: Forward-facing cavity mounted on the blunt nose of hypersonic vehicle is a good choice to reduce the stagnation heating. Presently, the study on hypersonic vehicles nose tip with forward-facing cavity mainly focus on its thermology characteristic, and little work can be found investigating the effect of cavity on aerodynamic force for a holistic vehicle. The CFD method is developed to investigate the effect of cavity geometry on aerodynamic performance of hypersonic vehicle with a forward-facing cavity on the nose-tip. Drag coefficient, lift coefficient and pitching moment coefficient of the vehicle for different attack angle are calculated. It is found that the cavity length to diameter (L/D) can not be a characteristic parameter in aerodynamic research, though it was used as a main characteristic parameter in investigation on the thermal protection. The length of the cavity L has little effect on aerodynamic characteristic of the vehicle, and the cavity diameter D has a crucial influence on the aerodynamic performance and the aerodynamic performance decrease with the D increasing. With the attack angle increasing, the drag coefficient, lift coefficient, pitching moment coefficient and lift-drag ratio of the hypersonic vehicle all increase.
Authors: Shao Jian He, Yi Qing Wang, Jun Lin, Li Qun Zhang
Abstract: Rubber/clay nanocomposites have been explored as alternative materials to replace expensive halogenated butyl rubber. In order to further improve their gas barrier properties, a simple and efficient method through sulfur modification was applied in this work. Excess sulfur was added into SBR/clay nanocompound to prepare sulfur modified nanocomposite via the formation of cyclic sulfide in addition to crosslinking. The vulcanization behavior, mechanical properties, dynamic mechanical property and gas barrier property of the nanocomposites were investigated. It was found that the sulfur modified SBR/clay nanocomposites showed much increased glass transition temperature and lower gas permeability.

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