Applied Mechanics and Materials Vols. 130-134

Abstract: The evaluation model of artillery firing efficiency is widely applied to firepower command&control and large-scale simulation, itis very important for improving precision and speed of calculation to enhance capability of firepower command&control and large-scale simulation. Two-dimensional subsection Simpson integration was introduced to evaluation the model, the analysis of two-dimensional subsection Simpson integration in theory showed that convergence speed of two-dimensional subsection Simpson integration enhance to O(h⁴). The simulation results indicate that, speed of two-dimensional subsection Simpson integration is higher 20 times than statistics experiment method, precision of two-dimensional subsection Simpson integration is a little higher than the typical numerical integration such as midpoint formula integration and statistical experiment method, but it can promotes precision by 10% than approximate computation method.

Abstract: A new algorithm to mine the frequent items in data stream is presented. The algorithm adopts a time fading factor to emphasize the importance of the relatively newer data, and records the densities of the data items in Hash tables. For a given threshold of density S and an integer k, our algorithm can mine the top k frequent items. Computation time for processing each data item is O(1) . Experimental results show that the algorithm outperforms other methods in terms of accuracy, memory requirement, and processing speed.

Abstract: In order to better determine experts’ weights in analyzing the credibility of simulation model, a new method is proposed in this paper. The deviation between experts is combined with Dempster-Shafer theory to construct the objective function of expert’s weights. And through analyzing creditability of simulation model of the ship electric propulsion system, the proposed method is proved to be feasible.

Abstract: Observability in passive location and tracking system is an important problem. This paper investigates the observability of multi-station time difference measurements system. For a 2D plane N orders movement target, three algorithms, linear system theory, nonlinear system theory and algebraic equations are used to demonstrate the observability of multi-station time difference of arrivals (TDOA) passive location and tracking system. The minimum of observation station and observation number are obtained when the targets are observability.

Abstract: Micro-CAES can balance fluctuations in supply and demand of electricity. In this technology, air is compressed with a motor/generator using low cost, off-peak or discarded electricity from wind power and stored underground in caverns or pipes. This pressurized air is released then be burned with gas in a combustor. The hot expanding gases drive a micro-turbo expander and run a motor/generator which, in turn, produces electricity during peak demand periods. By considering the factors including economy, reliability, environment protection, and CO₂ emission, a fuzzy overall evaluation model for different power supply mode is proposed. The related calculation and optimization are made. Linking with wind power, the overall performance of micro-CAES is best.

Abstract: In this paper, a numerical flow model combining with the Realizable k–ε turbulent model for compressible viscous fluid is presented for the simulation the flow perpendicular to one face of a cube in a straight rectangular duct; and the equations are solved with the finite volume method. The computed velocity field distribution shows that the proposed model is reliable and can be applied to the numerical simulation of turbulence flow in ducts.

Abstract: Semi-physical simulation of attitude control system is the more synthetically test and verify for designing of small satellite control system. It is an important means of small satellite development. However, the results of current semi-physical simulation system have a lot of non-intuitive. Compare with the actual environment, the simulation environment still has striking disparity. So the shortcomings affect precision of simulation. Based on the virtual display technology, the group semi-physical simulation system has been constructed for attitude control of small satellite due to the combination with xPC real-time environment, the simulation computer, high-precision single-axis air-bearing turntable, reaction wheel, air thrust device, fiber gyroscopes, sensors synchronizer, power subsystem and wireless devices virtual display computer etc. Semi-physical simulation achieved the visual simulation in orbit and tracked new information of virtual environment of space into real-time simulation computer. Simulation results show that the simulation system for real-time attitude and orbit position of small satellite semi-physical simulation has an excellent display effect. At the same time, Real-time transfuse of orbit information provides a more accurate space environment simulation. The simulation system of small satellite attitude control to design and evaluate the more direct and convenient.

Abstract: This paper is concerned with the numerical solution of two-dimensional flows in a rectangular meandering channel. The technique of boundary-fitted coordinate system is used to overcome the difficulties resulting from the complicated shape of natural river boundaries; the method of physical fractional steps is used to solve the partial differential equations in the transformed plane. Comparison between computed and experimental data shows a satisfactory agreement.

Abstract: The active power filter has two key link for harmonic current detection and respectively compensation current tracking. This article mainly aims at harmonic current detection link. Firstly, Analysis adaptive harmonic detection methods, then based on over to LMS (Least Mean Square) adaptive algorithm as the research object, in discussing the adaptive algorithm criteria. By comparing several simulation-based LMS algorithm to achieve the results of the filter,analyse the causes of the results.

Abstract: The micro Doppler effect of the radar echo signal of helicopter rotor is studied, and the formula of helicopter rotor echo is obtained. Then the received echo signal of helicopter rotor simulated is analyzed in time domain, frequency domain and time-frequency domain respectively, the analysis results show that it is a good method to extract micro Doppler of helicopter rotor echo by time-frequency analysis. According to analysis results, obtained a method to determine parity of blades and velocity of helicopter rotor, these methods can be used to identify helicopter.