履带车辆行驶平顺性仿真分析研究

应用履带车辆仿真软件ATV,建立整车多刚体系统模型和正弦波路面谱,进行了整车行驶平顺性的仿真分析,研究不同车速下车辆驾驶员位置的垂直振动加速度、水平振动加速度、以及人体承受振动的持续时间,并且通过与实测数据比较,验证了模型的合理性.     

履带车辆悬挂系统振动的半主动控制与仿真

恶劣路面上行驶的履带车辆的振动对车辆的性能、平顺性、操作稳定性及运动安全性都造成不同程度的消极影响。履带车辆悬挂系统振动的加速度是描述履带车辆振动程度的一个重要指标。首先提出了一个考虑负重轮的履带车辆悬挂系统的力学模型,并且建立了相应的运动微分方程组。又选取了一组新的描述悬挂系统运动的输出变量,然后应用二次型半主动最优控制理论,具体计算了正弦路面激励下悬挂系统在控制前后运动状态的改变。参数分析和数值仿真结果表明,通过选取合适的控制参数,就能使履带车辆悬挂系统的加速度得到有效的控制。     

履带车辆行驶循环的构建方法研究

基于行驶循环工况的仿真分析可以为履带车辆动力传动系统匹配提供新的技术手段,针对某履带车辆试车场的试验数据,提出了一种履带车辆行驶循环的构建方法.应用小波变换方法对试验数据进行了滤波处理.定义试车场一次整圈试验为一个运动学样本,通过统计学的相关性分析和速度-加速度概率分布分析,选出最接近样本集合的代表样本.试车场行驶循环...     

履带车辆悬挂质量系统振动的模糊控制与仿真

本文提出了一种模糊控制方法以控制履带车辆悬挂质量系统的上下垂直线振动和前后俯仰运动的角振动。建立了含8自由度的二分之一履带车辆悬挂系统的力学模型，同时考虑了履带车辆的垂直线振动和俯仰角振动的耦合效应。另外，本文也研究了不同控制力的组合对控制效果的影响，发现在转动控制中存在所需控制力的极小值。模糊控制的数值仿真结果表明在规则正弦路面和复杂随机路面下悬挂系统的加速度和俯仰角均可得到有效控制。     

某型履带车辆紧急制动动力学仿真分析

基于虚拟样机技术,用ADAMS/ATV模块建立了某型履带车辆紧急制动的动力学模型。通过实车的行驶试验和紧急制动试验对模型进行了验证,结果表明所建动力学模型在反映履带车辆行驶及紧急制动动力学行为方面能够满足工程分析的需要。将其作为分析平台,对履带车辆进行了以相同初速度在不同路面以及同一路面不同初速度情况下紧急制动动力学仿真分析,仿真结果表明,其符合在相同的路面制动初速度越大制动距离越远以及制动初速度相同的情况下,路面不平度越大制动距离越短的实际情况。     

履带车辆在不同行驶工况下燃油消耗量的仿真模型

该文首先利用曲面拟合法建立了发动机稳态工况的万有特性数学模型,然后建立了履带车辆在不同行驶工况下燃油消耗量的仿真模型,接着以某车辆为实例,应用 Matlab语言编程计算得出计算值,最后与试验值比较,验证了模型的有效性和准确性。     

某车辆车体振动特性及主动轮减振方案研究

为解决某履带车辆水泥路面行驶时的振动问题,测试了该车及变型车的振动特性,并以假定的激励建立了车速与车体周期振动频率公式,此公式获得的计算结果与测试曲线的基频基本一致,验证了激励假定的正确性.提出了3种关于主动轮设计的减振方案.     

履带对履带车辆车体振动影响的分析

基于LMS Virtual.Lab Motion建立了以行动系统为主的车辆—履带动力学模型和车辆—试验台架动力学模型(不含履带).利用仿真结果对比了两种模型在不同车速、不同路况下车体质心垂向振动加速度功率谱密度曲线的变化情况.从而分析出履带对车体振动的影响,同时也为履带车辆室内道路模拟试验的准确度提供了一定的参考.     

履带车辆行驶平顺性预测的仿真

履带车辆行驶平顺性预测仿真,以某型履带车辆为例,利用Matlab信号处理工具箱构建路面模型,以逆傅立叶法构造路面谱.以ISO 2361标准作为平顺性评价方法,对履带车辆在F级路面上的平顺性进行仿真.并用履带车辆模块和Pro/ENGINEER构造履带车辆虚拟样机,包括其结构组成及运动分析、模型建立及仿真分析.     

装甲车辆平顺性仿真及试验验证

该文研究内容为车辆(轮式、履带)在不平路面行驶和通过障碍时的平顺性问题。利用状态方程法建立了包括随机和确定路面轮廓、三维车体等较为通用的车辆行驶平顺性模型。并针对行驶振动中车轮与悬架的碰撞建立了专用模型。对某型装甲车辆进行了计算机仿真和验证,对模型的精度和有效性进行检验和评估。结果证明所建立的车辆—地面系统模型是有效的。该模型和建模采用的方法为装甲车辆的系统设计和动力学分析提供了一条途径。     

Stability of the Third Generation Intensifier under Illumination

The stability under illumination of transmission-mode GaAs photocathode sealed in the third generation intensifier is investigated by use of spectral response testing instruments. The variations of spectral response with the illumination times under weak and intense illumination are compared. The variations of photoemission performance parameters are also characterized. The results show that during initial several weak illuminations photocathode behaves no evident decay and a maximum sensitivity is achieved, while under intense illumination the sensitivity of photocathode begin to decrease largely at the first illumination. The calculated performance parameters show that the variation of surface escape probability with illumination times is a direct cause of instability of photocathode. It is also found that under intense illumination peak wavelength is moved towards short-wave and peak response is decreased, which shows that the ability of long-wave response of photocathode is decreased.     

Passive Acoustic Radar for Detecting Supersonic Cruise Missile

A Passive Acoustic Radar is presented as a necessary complement to electromagnetic wave radar, which will be expected to be an effective means for detecting cruise missiles. Acoustic characteristics of supersonic flying projectiles with diverse shapes are expounded via experiment. It is pointed out that simulation experiment could be implemented using bullet or shell instead of cruise missile. Based on theoretical analysis and experiment, the ““acoustic fingerprint““ character of cruise missile is illustrated to identify it in a strong noise environment. After establishing a locating mathematical model, the technique of acoustic embattling is utilized to resolve a problem of confirming the time of early-warning, considering the fact that velocity of sound is much slower than that of light. Thereby, a whole system of passive acoustic radar for detecting supersonic cruise missile is formed.     

Super-resolution Restoration of Remote-sensing Images

A novel image restoration scheme, which is super-resolution image restoration algorithm Poisson-maximum-afterword-probability based on Markvo constraint （MPMAP） combined with evaluating image detail parameter D, has been proposed. The advantage of super-resolution algorithm MPMAP incorporated with parameter D lies in the fact that superresolution algorithm MPMAP model is discrete, which is in accordance with remote-sensing imaging model, and the algorithm MPMAP is proved applicable to linear and non-linear imaging models with a unique solution when noise is not severe. According to simulation experiments for practical images, super-resolution algorithm MPMAP can retain image details better than most of traditional restoration methods; at the same time, the proposed parameter D can help to identify real point spread function （PSF） value of degradation process. Processing result of practical remote-sensing images by MPMAP combined with parameter D are given, it illustrates that MPMAP restoration scheme combined PSF estimation has a better restoration result than that of Photoshop processing, based on the same original images. It is proved that the proposed scheme is helpful to offset the lack of resolution of the original remote-sensing images and has its extensive application foreground.     

Design and Simulation of TF and TA Controller for Missile

A nonlinear terrain following(TF) and terrain avoidance(TA) controller is proposed for missile control systems. Based on classical TF algorithm (adaptive angle method), a new method for TF controller is proposed by using angle of attack. A method of obtaining terrain outline data from digital elevation map (DEM) for TF control is discussed in order to save store space. A TA algorithm is proposed by using bank-to-turn technique. The block control model, which is suitable for backstepping design, is given for nonlinear model of missile. Making full use of the characteristics of the system and combining block control principle and backstepping technique, a robust controller design method is proposed. Uncertainties in every sub-block are allowed, and can be canceled by using the idea of nonlinear damping. It is proved that the state tracking errors are converged to a neighborhood of the origin exponentially. Finally, nonlinear six-degree-of-freedom simulation results for the missile model are presented to demonstrate the effectiveness of the proposed control law.     

Design and Analysis of Test Schemes of Static Postponing Time on Shrapnels Used to Riot Control

The test scheme of static postponing time given in our actual national military test standard on shrapnels used to control riot is a nine-point test scheme on the combined action of three kinds of temperatures and three kinds of pressures,the consumed ammunitions are more excessive. Statistic analysis and tentative checkout about a lot of test data are done,feasibility gists are put forward for optimizing of the test design scheme. The optimizing design and data analysis of test scheme of the item are done by managing uniformity design theory, two scientific and reasonable six-point test schemes are confirmed. The feasibility and reliability of the optimizing design schemes put forward above are proved ulteriorly by test validating. The gained schemes not only have good design uniformity and little ammunition wastage and meet the test demand, but also have better forecast ability for the result data of other points using the mathematic models from the actual test points.     

Expert Systems Aimed at General Design of Projectiles

Expert systems aimed at the general design of projectiles can implement a series of intelligent designs, such as the design of HE shell, the scheme expounded and proved, the emulation analysis and calculation, etc. Aiming at the product design feature, the expert system adopts the object-oriented knowledge representation and all kinds of inference control engines to describe and reason the relevant knowledge regarding the product through the microcomputer. It embodies the foundation of emulation analysis and simulated manufacturing of the shell. It makes use of the method that knowledge expression is combined with condition of inference to carry out the overall design and emulation and reference.The paper gives the ways through which the functions can be achieved, gives the modularization of reference and the design methods of systematization, puts forward the method of knowledge expression and working interface, and supplies a platform for similar products of the shell category that can be quickly designed.     

Design of Non-fragile Satisfactory Estimator for Linear Continuous Perturbed Stochastic Systems

The design problem of non-fragile estimator is addressed for a class of perturbed linear continuous systems. The perturbations occur on the plant and estimator parameters. The estimator designed should force the error system to achieve the desired decay rate and force the steady error variance less than the specified upper bound irrdevancy of the admissible plant perturbations and estimator perturbations. Consistency problem of the decay rate with the variance upper bound is first considered via linear matrix inequality （LMI） approach. The solution of the estimator parameter under specifications to be consistent is then discussed. The consistency condition of specifications and estimator parameter solution are transformed to feasible or minimum problems subject to a set of LMI respectively. The method is illustrated by a numerical example.     

An Improved Scene-based Nonuniformity Correction Algorithm for Infrared Focal Plane Arrays Using Neural Networks

The improved scene-based adaptive nonuniformity correction （NUC） algorithms using a neural network （NNT） approach for infrared image sequences are presented and analyzed. The retlna-like neural networks using steepest descent model was the first proposed infrared focal plane arrays （IRFPA） nonuniformity compensation method, which can perform parameter estimation of the sensors over time on a frame by frame basis. To increase the strength and the robustness of the NNT algorithm and to avoid the presence of ghosting artifacts, some optimization techniques, including momentum term, regularization factor and adaptive learning rate, were executed in the parameter learning process. In this paper, the local median filtering result of Xij （ n ） is proposed as an alternative value of desired network output of neuron Xij （ n ）, denoted as Tij （ n ）, which is the local spatial average of Xij （ n ） in traditional NNT methods. Noticeably, the NUC algorithm is inter-frame adaptive in nature and does not rely on any statistical assumptions on the scene data in the image sequence. Applications of this algorithm to the simulated video sequences and real infrared data taken with PV320 show that the correction results of image sequence are better than that of using original NNT approach, especially for the short-time image sequences （several hundred frames） subjected to the dense impulse noises with a number of dead or saturated pixels.     

Piecewise Filter of Infrared Image Based on Moment Theory

The disadvantages of IR images mostly include high noise, blurry edge and so on. The characteristics make the existent smoothing methods ineffective in preserving edge, To solve this problem, a piecewise moment filter （PMF） is put forward. By using moment and piecewise linear theory, the filter can preserve edge. Based on the statistical model of random noise, a related-coefficient method is presented to estimate the variance of noise. The edge region and model are then detected by the estimated variance. The expectation of first-order derivatives is used in getting the reliable offset of edge. At last, a fast moment filter of double-stair edge model is used to gain the piecewise smoothing results and reduce the calculation. The experimental result shows that the new method has a better capability than other methods in suppressing noise and preserving edge.     

Bistatic Sonar Localization Based on Best Linear Unbiased Estimation

A best linear unbiased estimation （BLUE） algorithm for bistatic sonar localization is proposed. The Cramer-Rao bound for bistatic Sonar and the geometrical dilution of precision （GDOP） in different conditions are given. The simulation results show that the location accuracy of BLUE algorithm is higher than the weighted least square method.