Key Engineering Materials Vols. 439-440

Abstract: The aim of this study is to provide a simulation of air pollutant in a street canyon and investigates the impact of different turbulence models on the flow structure and air pollutant dispersion. Three studied k-ε turbulence models are evaluated to determine the most optimum turbulence model and the most suitable parameters of inlet boundary velocity and turbulent kinetic energy for simulating the pollutant dispersion in the present street canyon. The calculated data of the numerical model are then validated by comparing the extensive experimental database obtained from Kastner-Klein and Plate. Compared with the measured results, it can be concluded that modified RNG model with the inlet velocity profile and turbulent kinetic energy and turbulent dissipation rate provides the best calculated results, while standard and RNG k-ε turbulence models under-predict the pollutant concentrations.

Abstract: New type synchronous motor is made of a permanent magnet part and a reluctance part, there are import influence for the motor performance by the variable k, the fraction length of the permanent magnet part, and α, the displaced angle between the two part d-axis. The math model is derived based on Lyapunov stability, searching the appropriate k and α value, plotting stability regions, giving the simulation results. The calculation results are verified by simulation results.

Abstract: The design of a external sealing structures is of much importance for the miniaturization design of valve. The metal diaphragm structure is the main component of the external sealing structure. So the mechanical behaviors of the metal diaphragm are significantly necessary to be determined for the valve design. This paper, by numerical simulations, studies the mechanical behaviors of the diaphragm, including: i) the stresses and deformations of a three-layered metal diaphragm under the loads of axial force and high pressure, and ii) the effects of the diaphragm layer number on the axial force and the maximum equivalent stress under effective external sealing. These results provide guidelines for design and application of the valve and its diaphragm.

Abstract: Direct drive volume control（DDVC）electro-hydraulic servo system has synthesized the advantages of high power of hydraulic system and flexible control of the motor. It also has other features such as energy saving, high efficiency, small bulk and high reliability. On the background for application to the ship steering system, DDVC electro-hydraulic servo system for the control actuator of ship is designed and the mathematic model is made and simulated with Matlab/Simulink. The steering gears closed-loop system’s simulation obtained the perfect dynamic performances; verify the correctness of the design with its control strategy. It can satisfy the ships request of boat to steering gears system and the DDVC electro-hydraulic servo system will be a extensive prospective power equipment of the control actuator of ship in future.

Abstract: The technique of centrifuge model test has been widely used in geotechnical mechanics and engineering because of its low cost and low test scale. In order to investigate the dynamic behaviors of the geotechnical model under explosion, we are developing an explosion geotechnical centrifuge. The dynamic environment of explosion is necessary to be determined for the strength design of the centrifuge nacelle. This paper presents the dynamic force measurement of the model container to the centrifuge nacelle under a typical explosion. Firstly, three cylindrical supports were designed and calibrated by quasi-static compressive tests. The force-strain relations are measured and linearly fitted. Secondly, an explosion test was performed and the dynamic strain histories of the supports were measured. Then the dynamic force histories were obtained combined with the calibration results. The investigation provides an understanding of the dynamic environment for the centrifuge nacelle design.

Abstract: Recently, palmprint identification has been developed for security purpose. In this paper, we propose a novel palmprint recognition scheme which has three features: 1) representation of palmprint images by Local Binary Pattern (LBP); 2) dimensionality reduction by tensor subspace learning; and 3) recognition by multiple kernel classification method based on tensor analysis. LBP can effectively capture substantial palm features while keeping robustness to illumination. Then we reduce the dimensionality of each palmprint samples based on tensor subspace learning which can preserve the spatial structure of LBP. Tensor multiple kernel SVM classifier is finally employed for palmprint recognition. Experimental results on PolyU palmprint database show the effectiveness of the proposed method.

Abstract: The coupling coefficient of twin-core fiber is discussed with coupled-mode theory in this paper. It shows that the coupling coefficient is related with the pump wavelength, the core diameter, the distance between the centers of the two cores and the relative refractive index difference. And the parameters of the twin-core fibers can be optimized to satisfy different requirements. Using the theory, the twin-core fibers are fabricated by an improved method. The measurement results have an obvious progress than previous work.

Abstract: Creating many replicas in the processing of data-intensive jobs in data grid is an efficient strategy. Replica replacement is the crucial step to this strategy. Economic model, popularity model and hybrid model etc. have been proposed to solve this issue of replica replacement with analysis and prediction based on each data file, however, these models neglect association relationships among different data files. To find out these association relationships hidden in data-intensive jobs, Apriori algorithm in data mining field is adopted to analyze behaviors of each data-intensive job. An associated replica replacement algorithm based on Apriori approach in data grid is proposed in this paper. This algorithm has two major steps: 1) associated behavior analysis and classification of data files in each node; 2) generation and application of replica replacement rules. Our proposed algorithm is simulated in Optorsim to be compared with LFU algorithm. The experiment shows that there is a relative advantage compared with LFU in mean job times of all jobs, number of remote file access and effective network usage perspectives.

Abstract: As the Russian government has increased investment and management in the Global Navigation Satellite System (GLONASS), the paper improves the acquisition and tracking algorithms of GLONASS receiver based on the primary study of GPS receiver. On the platform of MATLAB, the Fast Fourier Transform (FFT) acquisition of the GLONASS intermediate frequency (IF) signal has achieved by GLONASS signal simulator and PC. At the same time the delay lock loop (that is early-late loop) and coast phase lock loop is used to achieve the code tracking and carrier tracking and decode the navigation data. Just as the experimental results shown, GLONASS IF signal can be acquired and tracked by these algorithms which are suggested in this paper. And it has laid a solid foundation for the study of a complete GLONASS software receiver in the future.

Abstract: The article describes the USB-based implementation of the designing Hardware System of a GPS IF data collector, needed to collect and save a file of GPS IF data which is used to do acquisition experiment. This instrument is based on GP2015, EP2C35F484 and CY7C68013A and so on. The logic circuit of this design is programmed into FPGA to optimize and verify under the platform of Quartus II. USB firmware is developed under the platform of Keil. Experimental results show that the GPS signal can be collected and saved as a file of GPS IF data, and this system operated stably and safely.