Advanced Materials Research Vols. 211-212

Abstract: Using numerical simulation to study solar water heating system it will be fast to obtain data and have a reasonable conditional statistical forecast. In this paper, based on the numerical model of an actual forced circulation solar water heating system, the whole year thermodynamic performance in a forced circulation solar water heating system are simulated and studied. It is shown that the efficiency of energy utilization and the heat loss of collectors in the system are closely related with the out door temperature and main efforts should be on the collectors.

Abstract: In the present paper, the effects of four structural parameters at three levels on the reliability and sensitivity of structure are investigated. Sensitivity of parameters is achieved by the range analysis and the significance of parameters is achieved by the variance analysis. A response surface based on orthogonal experimental design and finite element calculations is elaborated so that the relation between the random input variables and structural responses could be established. The First-Order Reliability Method (FORM) as an approximated method is used here to assess the reliability. Comparing with the results of Monte Carlo simulations by ANSYS for a numerical example, the effect of sensitivity analysis has been proved, while the precision of the reliability and sensitivity should be improved in the future.

Abstract: With the rapid development of information technology, IT industries and IT products has become a new vitality industry type of economic field. The management capability maturity Model (CMM) is an important to evaluation the management ability of a enterprise, and at present has been widely used. Using the theory of fuzzy mathematics to design a management capability maturity model of IT project, and make the comparative analysis according to the ERP system development process of the different IT enterprise.

Abstract: GCr15 alloy produced by hot-forged is subjected to equal channel angular extrusion (ECAE) process at 950°C. The microstructure of GCr15 steel via ECAE and annealed is studied by an optical microscope. The effect of ECAE and annealing on the wear properties of the alloy is also investigated. The results show that the grain size reduced from 50 mm to 10 mm via one pass ECAE, and the hardness of the alloy is increased. The wear mass loss of the alloy is greatly reduced due to the grain-refinement after ECAE and annealing.

Abstract: This paper discusses the design and analysis of a direct-drive linear slide used linear mortor. The alloy steel carriage is fully floated by twelve hydrostatic bearings, and it is force-closed. It has very high stiffnesses, 1700N/mm in vertical direction and 690N/mm in horizontal direction. The working stroke of slide is 200 mm. The slide is driven by a ironless linear motor. The optic linear encoder was used for the measurements and feedback. To analyze the static and dynamic performance of the slide, the modelling and simulation process, using the finite element analysis method, is presented.

Abstract: In this paper, a high precision positioning control method based on the learning algorithm with the reference model is proposed. The reference model is composed of a plant model and a feedback controller. In the proposed control method, disturbance, modeling error and nonlinear characteristic can be effectively compensated by the neural network-based controller, which learns the reference model. Moreover, the control-input saturation problem due to the over-learning for the neural network can be avoided. The effectiveness of the proposed control method is experimentally verified using the precision positioning equipment with nonlinear friction characteristics.

Abstract: In order to implement the measurement of two-dimensional small angles, a method of modulating optical-path differences through a wedge is put forward, based on Michelson interference principle. By promoting the wedge with a voice coil motor, optical path that pass through the wedge will be changed. Then the optical-path differences on fixed points of the receiving screen will be cycle changed. Then the interference fringes will be carried out on periodical motion. Utilizing voice coil motor and right angle flexible hinge moving cycle, the relationship between the driving voltage and the displacement of wedge also has been analyzed detailedly. The experiment results show that there is a good linearity while the driving voltage is in the range 3.2v-7.5v. Modulating optical-path in this linear range, precise measurement of two-dimensional angles can be realized.

Abstract: This paper proposed an improved thermal-electric-displacement FEM model for spark plasma sintering (SPS), which fully considered the variations of therma-electrical material parameters, contact resistances and contact boundaries due to the densification process. The simulation shows that such an alterable boundary condition builds a remarkable temperature gradient in the axial direction along the inner wall of the die, and the local change of the temperature at the contact interfaces can be described more exactly. The experiment and the simulation are in a great agreement. The developed SPS model can be used as an aiding tool to optimize the SPS process parameters of metal powders.

Abstract: The author introduced a new stair-climbing and obstacle-traversing robot system. According to its working environment, the parameters of driving wheels were determined with the optimization target of rotation axis’s undulation amplitude; The gear ratios of the driving planetary gear train were determined by running resistance, which can realize the automatic switching between rotation and revolution; According to its applicable situation, the robot’s control system was designed as a human-machine interaction model.

Abstract: A fastening of sleeper is an important part to bind rail, sleeper and foundation under the track, which requires enough strength, elasticity et al.. This article focuses on the common occurrence of fracture on a casting fastening baffle by metallographic analysis of the materials of different part in the casting, and reaches the conclusion that the unevenly distribution of chemical composition is due to the different cooling rate of different wall thickness. The low carbon content in thin wall and the lack of pearlite with high strength in matrix structure aggravates the danger of the emergence of cracks. Then a solution is put forward, which is to improve the structure of the casting and reasonably arrange the inner runner when casting.