Abstract: A method for mechanics analysis of bar structure materials has been presented in the paper. The method is based on the theory of kinematics, dynamics, and programming techniques. After deriving of relevant equations, detail analysis about positions, velocities, accelerations, and angles, angular velocities, angular accelerations of bars as well as other parameters relevant to bar structure materials to be searched can be obtained in the paper. Relationships between various parameters and variables of bar structures have been derived according to different working states of bars. The method put forward in the paper is a feasible and high efficient method for mechanics analysis of bar structure materials in the design of mechanism.
Abstract: In this work, syntactic foams made of microballoons having same wall thickness ratio but with different particle size was prepared. Microballoons of three size distribution ranges were selected .The property of the syntactic foams were studied by quasi-static compression test. The experimental results show the microballoons size doesn’t influent the mechanical properties of the syntactic foam significantly. The failure mode of the syntactic foams was also studied in this work.
Abstract: We present metal detection using eddy current sensors by combining 2 high-frequency sensors and 1 low-frequency transducer together on the basis of eddy current effect. The two high frequency sensors in this design work at different frequencies which implement the complementary of linear range of the detection and the analog signal is transformed into digital signal by ADC for further processing using ARM9 processor to achieve wide range, high sensitivity, and precise metal detection.
Abstract: The shear stress jump boundary condition that must be imposed at an interface between a porous medium and a free fluid in an enclosure is investigated. Two-domain approach is founded and finite element method is used to solve the problem. Three stress jump coefficients 0, 1, -1 are analyzed for different Rayleigh number, permeability and thickness of porous layer. Variation of Maximum stream function and Nusselt number show stronger convection and heat transfer when the stress jump coefficient is positive. There is little distinctive in flow and heat transfer when the value of coefficient is equal to 0 and -1.
Abstract: In the XRD spectrum analysis, there is a lot of measurement noise. It will cause the influence which can not be ignored for the elemental composition analysis. In this paper, the noise of YBaCuO nano powder in XRD was studied. In order to eliminate its influence, Wigner-Ville Distribution (WVD) was used to improve the anti-noise capability. First, based on a comprehensive study of various noise signal characteristics and model structures, the anti-noise capability of WVD was systematically studied in accordance with theoretical analysis. Then, proposed SPWVD and RSPWVD were studied and used to improve anti-noise capability. Last, by simulation experiment, compared and verified the conclusion. The results show that RSPWVD for additive noise and non-zero mean multiplicative noise has better anti-noise capability. It could eliminate the influence of the noise of YBaCuO nano power in XRD.
Abstract: The existence of measurement noise in XRD analysis brings about unneglected effect on analysis of elementary composition. In this paper, in order to eliminate the effect of the noise of nano powder of YBaCuO in XRD, Short Time Power Spectral (STPS) was presented in this paper. And the anti-interference capability of STPS was systematically studied and improved in accordance with theoretical analysis. Experiments were carried out to test the anti-interference ability of STPS with inertia filtering. The simulation results show that STPS spectrum of signals with additive noise or multiplicative noise is quite clear. It indicates that STPS with inertia filtering can overcome influence from different noise, and it has better capability of anti-interference from additive noise comparatively.
Abstract: The accuracy of the grey model is not high for the monotonic decreasing data and the error can not avoided. The model can not satisfy the compatibility conditions and then it is not accordant with the linear transformation. The paper adopts the equal interval unbiased model and takes one of the components in as the initial values. By this method it induces the parameters in the grey unbiased GRM(1,1) model and establishes the equal interval unbiased model based on the reciprocal AGO process. The model has high accuracy and has good value in the theory and practice. The examples show it is practical and reliable.
Abstract: The accuracy of the traditional grey model is not high for the monotonic decreasing data. The paper uses the opposite-direction accumulated method and makes full use of new information combined with optimization of the background values. It induces the formula of the parameters in the model and establishes the grey new information GOM(1,1) model in which it is based on the opposite-direction accumulated operation and optimization of the background values. It is a new method of the grey model. The examples show it is with higher accuracy than that of non-new information model.
Abstract: The Brushless Direct Current Motor (BLDCM) is in nature of high power density, high reliability and easy control etc, growing with the development of microcomputers, new power electronic devices, control theories and low cost rare earth permanent magnet material. The applications of a new permanent magnet material are described in this paper,such as in manufacture of parts of stereo,automobile devices,medical instruments and computer hardware, etc.Besides,the paper also discusses the prospect of its development and the problems in its production.Aiming at the BLDCM with a Hall rotor position sensor, a motor drive controller is designed by pure hardware approach. In this paper, a simple design procedures is described that can be implemented to decrease the material cost of a BLDCM often found in domestic appliances and automotive applications. According to the experiment’s result, this controller has the advantages of easy debugging, high anti-interference ability, larger driving power, low volume and low cost in large scale production.