Applied Mechanics and Materials Vols. 229-231

Abstract: In view of the high complexity and uncertain characteristics of traffic flow in urban expressway, a fuzzy logic approach is proposed to adjust the number of vehicles entering a mainline of urban expressway via entrance ramp during rush traffic times. Taking account of the combine influence of traffic state on mainline and the on-ramp queue at Surface Street, the on-ramp fuzzy controller of urban expressway is designed based on such traffic information as the speed downstream mainline, time occupancy upstream mainline, and on-ramp queue length at the Surface Street. Simulation research based on MATLAB toolbox is carried out and the results show that the fuzzy controller is feasible and reasonable to confirm the number of vehicles entering the mainline of urban expressway.

Abstract: For disadvantage of the methods that are used to evaluate inter-cluster separability measure, a novel separability measure is proposed and applied to directed acyclic graph support vector machine. The distance between cluster centers and distribution of samples in feature space are both considered by the algorithm. Firstly, use hyper-sphere support vector machine to obtain minimal bounding hyper-sphere of each cluster, according to the radius and centers of minimal bounding hyper-spheres, introduce the concept of inter-cluster separability measure in feature space, get the matrix of inter-cluster separability measure according to the concept, finally construct the directed acyclic graph according to the matrix. The experimental results show that the algorithm has higher classification precision, comparing with old directed acyclic graph support vector machine.

Abstract: In this study, performances of double delta-doped AlGaAs/InGaAspseudomorphic high electron mobility transistors are investigated. Simulation results demonstrate good performance for this structure. Form simulation, the structure demonstrates a maximum current gain cutoff frequency of 145GHz for 100nm gate length, a peak extrinsic transconductance of 526mS/mm, and a maximum saturation current density of 350mA/mm.

Abstract: The dynamic behavior of step motor is of great importance in the field of the developing high performance open-loop system. The dynamic simulation model of a 3-phase reluctance step motor was established on neglecting the mutual inductance between phases and magnetic circuit saturation. The simulation results were verified by the motor characteristic under deferent controller. The characteristics of the motor were analyzed under various operation and load conditions. The work provides an active approach for further designing and controlling the step motor.

Abstract: The DC link current spectrum has important effects on the active state and life of the battery cell and the bus capacitance in the three-phase inverter. Based on the load of PMSM (Permanent Magnet Synchronous Motor), the DC link current characteristics are presented intuitively using the computer simulation. The paper discusses the method and procedure to the simulation model that includes several key modules: PWM module, inverter module, and PMSM module. The simulating results are presented and analyzed.

Abstract: In the process of ground simulation object maneuver simulation in large-scale operation simulation, an efficient path planning method based on A*algorithm is proposed. By means of introducing all kind of geography factors and security factors into heuristic function, the plan reaching method solves the problem of finding an optimal path under acquiring enemy's situation and terrain data. Experiment results show that it has effectively raised path planning speed of A* algorithm and the scheme is practical and feasible.

Abstract: According to the internal physical structure of photovoltaic cell and output V-I characteristic, the paper construct a solar module simulating model by engineering calculation method under the Simulink environment. In the light of the limited parameters of photovoltaic cell (PV), the model can give the entire output characteristic curve under the different intensity illuminations and the various temperatures. At the final of the paper, MPPT to solar module adopted a special method is researched based on the Simulink.

Abstract: The DOA Estimation of the MIMO radar is widely used to determine the position of the objects. Having been considered the multipath communication environment, this paper estimates the DOA information of low elevation targets using beam space MUSIC algorithm based on the model of uniform linear array of MIMO radar. Simulations have shown that the algorithm is effective in the multipath spread environment, and the resolution of the DOA estimation of angular is about 0.5°

Abstract: The principle of Particle Swarm Optimization (PSO) and Homotopy Optimization (HO) is introduced. For the purpose of improving the local-searching efficiency of the PSO，HO-PSO is presented by combining the PSO with HO. New space homotopy curve produced by homotopy particle function directs the particle’s local optimization. For comparison，the methods of HO-PSO, PSO and FEM(Finite Element Method) are used to calculate the tunnel parameter inversion of the Shuibuya Project on the basis of the measured displacements. The result shows that HO-PSO takes smaller time compared with PSO and FEM in a same precision level, and the calculated values are in good agreement with the measured values，which also indicate that the HO-PSO can be well applied to the displacement back analysis in tunnel engineering.

Abstract: A location method based on seismic wave detection was put forward. The seismic wave was collected by high-precision seismic sensors which were set as five-element-square-array structure. The distance and azimuth angle were acquired according to the time delay estimation between each sensor. The result of experiment shows that the location method is effective and has a high precision.