Advanced Materials Research Vols. 181-182

Abstract: Weibull distribution is one of the most widely used model in reliability analysis of NC machine tools. In order to assess the reliability of NC machine tool, Generalized Expectation Maximization (GEM) algorithm is used to estimate parameters of mixture Weibull models. Akaike information criterion (AIC) and Bayesian information criterion (BIC) are used as comprehensive criteria to select the number of subpopulations of mixture models. The results show that mixture models are more suitable to assess reliability of NC machine tools than that of single model. Root mean square errors (RMSE) of mixture models reduce by 87.5% than that of single model. Reliability evaluation results of machine tool, such as MTBF etc., are given.

Abstract: With the improved Apriori algorithm mine the potential association rules among courses from a large number of college students’ results. First is data preprocessing, which includes course options, students (transaction) options, results classification, category statistics and Data transformation. Then carry the experiment and analyze the experimental results in detail. At last, get association rule guiding to further teaching.

Abstract: In flexible roll forming, the horizontal movable sheet steel can be formed by controlling the servo motor to drive the multi-pass vertical movable roll. Only when the longitudinal movable distance of the roll in every pass matches exactly the contours of the sheet steel in time and space, the designated cross-section shape can be formed. Controlling the servo motor by applying the configuration programming is a common approach to achieve roll motion, but will not be able or difficult to realize by the configuration programming for complex contour without the rules such as hyperbolic, or the molding product in asymmetric cross-section shape, however, there are two other approaches such as simplifying the curves and using similar shapes to fit the process. As for the complex non-symmetrical curvature shapes, this paper adopts the variable time-domain servo motion control method to form the sheet steel. Experiments show that the variable time-domain servo motor control is a good motion control method for the sheet steel forming in complex cross-section shape.

Abstract: This paper introduced working principle of dual-coil self-sensing actuator based on magnetically controlled shape memory alloy (MSMA). The ANSYS software was used to establish the finite element model of MSMA dual-coil self-sensing actuator. Edge element method was adopted to analyze the MSMA dual-coil self-sensing actuator's 3-D static magnetic field under the influence of different excitation voltages. The analysis obtained MSMA and silicon steel sheet distribution of magnetic induction intensity and the magnetic field intensity, has further confirmed the reliability of MSMA dual-coil self-sensing actuator, and has given the MSMA length relations along with the magnetic induction intensity changes. The results show that magnetic field analysis has certain reference value to the MSMA practical application.

Abstract: This paper is concerned with the power and fuel economy performance simulation study of power splitcontinuously variable transmission(PSCVT). Firstly, mathematic model of PSCVT is established and the shifting rule is designed based on the introduction of PSCVT working principle; Secondly, the fuzzy-PID controller is designed according to the control requirements of electronic control system; Thirdly, the vehicle model with PSCVT and engine model are established to carry out the PSCVT power and fuel economy performance simulation. The simulation results indicate that the vehicle fuel consumption with PSCVT is reduced distinctly with the same power performance.

Abstract: Using BP Neural Network to optimize AE characteristic parameters of crack in drawing parts.By detecting the optimized characteristic parameters of crack, the crack in drawing parts are identified.According to the quality of drawing parts,the output of the network are crack signal and normal signal.Comparing the sensitivity of the input characteristic parameters on the output characteristic parameters,then pick the characteristic parameters which have bigger sensitivity values.Finally,the AE characteristic parameters such as Rise Time、AE Event Counter、Energy、Amplitude、Frequency Centroid can represent the signal of crack in the drawing parts better.These five characteristic parameters can identify the crack signal in the forming process of the drawing parts.

Abstract: In order to compare the steady multi-phase and unsteady calculation in double-suction centrifugal pump application, this article simulates the internal turbulent flow of the 150S-50 double suction centrifugal pump. Numerical simulation uses realizable turbulence model, simulating with two methods of steady multi-phase and unsteady in 7 cases. Based on the numerical simulation, the head, shaft power, efficiency were calculated, the simulated performance curves of a double suction centrifugal pump is processed. The results show that: The results of unsteady simulation are closer with the experimental data.

Abstract: In this paper, we studied the effect of the temperature and the initial concentration of sodium bromate (NaBrO3) on the aggregation-disaggregation self-oscillation for a polymer chain. The polymer chain consisted of N-isopropylacrylamide (NIPAAm), Ru catalyst of the BZ reaction and Acrylamide-2-methylpropanesulfonic acid (AMPS) as a solubility control site. The concentration of sodium bromate and the temperature significantly affected the self-oscillating behavior and the period of the aggregation-disaggregation self-oscillation. Moreover, the amplitude of the aggregation-disaggregation self-oscillation of the AMPS-containing polymer solution decreased with time. The damping behavior is originating from the increase in the size of the polymer chain. In addition, this study clarified that the period of the self-oscillation of the AMPS-containing polymer solution in the strongly acidic condition was significantly shorter than that in the acid-free condition.

Abstract: Perovskite KTa0.65Nb0.35O3 (KTN) thin films were grown by pulsed laser deposition (PLD) on single crystal SrTiO3 (100) substrates. X-ray diffraction (XRD) analyses illustrate epitaxially grown of KTN thin films along the (100) orientation. The surface morphology of films observed by atomic force microscope (AFM) showed that, the surface of films was smooth and uniform built from regular, ordered and dense grains with the root mean square (RMS) roughness of 5.602 nm. Linear and third-order nonlinear optical properties of the films were investigated by using transmission spectra as well as the Z-scan technique with femtosecond laser pulses, respectively. The open-aperture and closed-aperture Z-scan curves of KTN thin films were obtained in the first measurement. The calculated nonlinear refractive index was , the nonlinear absorption coefficient is = , and the real part and imaginary part of the third order nonlinear susceptibility are and respectively.