Advanced Materials Research Vols. 211-212

Abstract: With increasing of the speed of the train, the requirement of the performance of the braking friction materials is more and more higher. It is urgent to find new braking materials to satisfy the rigorous using environment. C_f/SiC has the broad application prospects when it is used as a new kind of braking material. On this article, in order to shorten preparation cycle and reduced production costs, short carbon fiber is substituted continuous carbon fiber felt. Cf/SiC brake materials were prepared by the way of molding compression-pressureless sintering with resin binder at 1800°C, 1850°C and 1900°C, respectively. The effect of sintering temperature on bending property of brake material was researched. The experimental results show that with the increase of sintering temperature, the bending strength of Cf/SiC brake materials rose first and then fell. If sintering temperature is too high, which will lead the crystal grain to grow up and the crack is easy to produce. Finally make the bending strength of composites reduced. When sintering at 1850°C, the bending strength of the specimen reached maximum. At the same experimental condition, the bending strength of Cf/SiC brake material sintered at 1850°C is 18.81MPa, compared to the sample sintered at 1800°C and 1900°C, the bending strength of the specimen is increased 14.56% and 5.26%, respectively. The toughening mechanism of carbon fiber debonding and fiber pull were generated in the process of bending fracture. The fracture model of composites is pseudo-ductile type.

Abstract: Vibrating machine based on the needs of practical work, combining hydraulic technology and vibration technology, presenting a design of new stepless force regulation vibration exciter, introducing the design and features of stepless force regulation vibration exciter, expounding the detailed actualization method and physical design and realization process of stepless force regulation.

Abstract: this paper mainly reviews and analyzes the design history on "decoration is evil” and makes a discussion about the contradiction. It avoids the misunderstanding about the comparison of paper-based text, combines contextual elements of the information age and figures out the different features of the current decorative performance and the possible space for multivariate development.

Abstract: In order to solve the key technical problem in maintenance and repairing of heavy CNC machine tools, the concept of precision reliability and its forecasting module are proposed. The method is especially used for researching of reliability of heavy machine tools of which the samples are not enough for statistical methods. Firstly, spatial error module is established for a type of super heavy mill &boring machine tool based on multy-body kinematics. Then, the effect of wearing amount of kinematic pair of machine tools on machining precision is researched. Therefore forecasting modules for maintenance period and premature wearing of heavy CNC machine tools are built up. The method proposed can be used in calculating for maintenance period of heavy machine tools, analyzing for source of machining errors, and optimal design for total life of CNC machine tools. It can also be used in research of reliability for similar product of single piece or small batch.

Abstract: Microstructural characteristics of A356 alloy prepared by low superheat pouring were researched, and the fractal dimensions of morphology of primary phase in the alloy was calculated. The results indicated that morphology of primary phase in A356 alloy belonged to fractal structure, and the microstructural characteristics in the alloy can be characterized by fractal dimension. There were the different fractal dimensions for the morphology of primary phase prepared by the different process.

Abstract: When Permanent Magnet Synchronous Machines (PMSM) working with rated load or overload, stator iron loss and copper loss, bearings friction loss, permanent magnet (PM) eddy-current all will cause PM temperature rise. In this condition, the PM is affected by the temperature and the stator of the reverse magnetic field generated prone to arouse demagnetization phenomenon, it will directly affect the performance of permanent magnet machines. Previous calculation method which used magnetic circuit method to analyze PM demagnetization characteristics cannot reflect the actual working condition of PM. Firstly, the calculation formula of PM thermal stability is deduced in this paper. Secondly, demagnetization characteristics are analyzed based on FEM, which can reflect the actual working condition of PM more accurately. This paper providing reference basis for optimum electromagnetic design, PM selection and optimum PM design.

Abstract: Continuous attribute discretization based on rough set is to got possibly minimum number of cuts, and at the same time it should not weaken the indiscernibility ability of the original decision system. In order to obtain the optimal cut set of the continuous attribute system, based on research the choice of candidate cut set, this paper presents a heuristic genetic algorithm for continuous attribute discretization to decision tables. In this algorithm making the importance of the continuous cut as heuristic message, a new operator is constructed to not only maintain the discernibility of the cuts selected, but also improve local search ability of the algorithm. Compared the performance of this method with the others’, this method is proved effective and superiority.

Abstract: In carries on the multi-objective movement track, because often the goal covers, factors and so on merge, separation to cause the track defeat. Proposed with the dynamic background modeling technology and the RGB three channel chromatic aberration law gain target complex group, then uses the Kalman filter forecast movement goal initial parameter, uses the improvement the Camshift algorithm to iterate gradually again approaches each goal exact location, has realized to the multi-objective auto-adapted tracks. The massive experiments indicated that this algorithm robustness is good, auto-adapted ability.

Abstract: An experimental vibrational cooling-shearing slope was developed to prepare the ZAlSi9Mg semi-solid alloy. The results show that the molten alloy is nucleated heterogeneously under shearing of the gravitation and vibration on the inclined cooling plate surface. Primary α-Al phase converts gradually from the cellular dendrite into tiny spherical or granular crystal. Under 600°C of pouring temperature, 600mm of casting length and 50Hz of vibration frequency, the semisolid alloy melt with good microstructure can obtained. In the alloy melt the average grain size of the original α-Al phase is 50μm, and its shape factor is 0.71. Mechanical vibration can refine obviously the microstructure of ZAlSi9Mg alloy. Along with increasing of vibration frequency, the original α-Al phases are refined obviously, their roundness is improved.

Abstract: Multi-model predictive control has become an effective method for nonlinear system. But the traditional multi-model has large tracking error compared with desired output when it is used to solve the operating condition with large scale transition. To solve this problem, this paper presents a new structure of multi-model called multi-hierarchical model. The new structure consists of many layers that each layer is constituted of different number of multiple models. In each layer, multi-model is obtained by partial least squares method after k-means clustering algorithm divides the global working spaces into desired parts. Because of this special structure, the models chose from different layers can deal with the operating condition changed with large scale. At the end of this paper, experiments are carried on the pH neutralization process which is a MIMO nonlinear system and the simulation results demonstrate that the multi-hierarchical model is superior to single-hierarchical model with smaller model tracking error faster convergence speed and better stability.