大长径比自旋弹箭横向自振特征的有限元计算方法与结果分析

本文研究大长径比自旋弹箭在飞行时横向振动的自振特性.本文将转子动力学应用于弹道学，采用有限元法，建立自旋弹簧横向振动自振特性方程。同时给出了计算方法，利用该方程和该方法，开发了相应的计算程序，通过数值计算，可给出细长旋转弹簧飞行时的进动转速和临界转速，以及上应的位移和角度振型。利用该程序，进行了实例计算和分析。     

悬臂板振动控制传感器/致动器优化配置

针对悬臂板的振动主动控制问题，首先利用有限元分析方法给出了悬臂板的动力控制方程。对于单独控制悬臂板的每阶模态振动，采用同位配置的方法，利用有限元分析方法分析传感器／致动器的配置，给出了目标函数，并将有限元分析方法与遗传算法结合，给出了一种新的传感器／致动器优化配置方法。     

数字射频存贮器信号重构的性能分析

从功率谱角度分析了数字射频存贮器（DRFM）信号重构的性能,给出了分析方法和典型雷达信号的分析结果。通过计算仿真,得出了零阶保持信号归一化能量随中心频率变化情况。还给出减小零阶保持产生信号失真方法,并给出补偿滤波器的传递函数。     

大长径比自旋弹箭横向自振特性的有限元计算方法与结果分析

本文研究大长径比自旋弹箭在飞行时横向振动的自振特性。本文将转子动力学应用于弹道学 ,采用有限元法 ,建立自旋弹箭横向振动自振特性方程。同时给出了计算方法。利用该方程和该方法 ,开发了相应的计算程序。通过数值计算 ,可给出细长旋转弹箭飞行时的进动转速和临界转速 ,以及相应的位移和角度振型。利用该程序 ,进行了实例计算和分析。     

瞬态信号测试的自适应采样策略

研究了瞬态信号测试过程中采样设计所面临的基本问题，根据多项式预测器的数学模型，研究提出了适用于瞬态信号测试的自适应采样策略，给出了零阶和一阶自适应采样算法，并给出了软件模拟结果。     

大长径比低旋尾翼稳定火箭弹最佳转速的确定

为了提高射击精度和密集度，对于尾翼稳定火箭弹，一般都采用低速旋转的方式消除推力偏心、质量偏心和气动偏心等的影响。但低旋时火箭弹转速应避免共振转速．即保证出炮口后弹轴章动角迅速衰减；大长径比尾翼火箭弹在飞行时自身还会产生弹性随机振动，转速设计还应避开火箭弹的固有振动频率，以防止发生结构共振。文中采用ANSYS有限元软件计算火箭弹的固有振动频率和动力响应特性，并依据这些计算结果给出最佳转速的确定方法。     

自行火炮变速箱瞬态过程振动信号的时频分析研究

讨论了一般机械在瞬态过程和稳态过程中所呈现出的不同振动特性，提出了基于瞬态过程分析机械故障诊断的必要性。针对瞬态过程诊断问题，将时频分析方法应用于非平稳信号的处理，同时针对时频分布图利用Hough变换，提取分布图中的线性部分。最后，给出自行火炮变速箱在不同工况下的瞬态过程振动信号的时频分析实例。实例证明，本文提出的方法对机械设备非平稳振动描述是可行的，对机械设备的故障诊断是有效的。     

某型多管火炮的振动模态分析

为研究某型多管火炮的振动特性，在其几何模型基础上，提出了该型火炮模态分析方法，确定了试验点。基于SC310W多通道数据采集系统，组建了该型火炮的模态分析系统，利用锤击法对该系统进行了模态试验，获得了冲击激励力与振动加速度响应信号与频谱及其频率响应函数。利用稳态图法，获得了前7阶系统的振型及各阶振动频率，并给出了模态分析的置信因子。     

基于DSP的步进电机高精度变速控制研究

分析步进电机DSP控制转速的基本原理和实现方法,研究确定信号控制步进电机转速的积分定时调频算法.针对非确定信号输入实现高精度变速控制问题,提出了具有重复误差补偿性能的梯形近似调频算法.利用Matlab对两种算法进行仿真,并采用DSP开发平台完成步进电机变速控制实验,结果表明,梯形近似调频法在步进电机变速控制中能有效地提高速度控制精度.     

基于Laplace先验和稀疏块相关性的旋转机械振动信号贝叶斯压缩重构

为通过无线传输实时监测装备状态,针对机械振动信号采样频率较高导致压缩重构困难的问题,将Laplace先验模型和振动信号周期性稀疏块相结合,提出一种改进的贝叶斯压缩感知算法。建立基于Laplace分布的贝叶斯先验模型,相对于高斯先验具有更强的稀疏促进作用。根据机械设备转速和采样频率计算振动信号类周期,对信号进行周期性分块,并基于多稀疏块共享相同超参数的特点,采用快速相关向量机迭代估计出原始信号期望。选取两级平行轴齿轮箱作为研究对象,进行压缩重构仿真实验。结果表明,该方法在相同稀疏基下能有效改善机械振动信号的重构效果。     

Nitrosation and Nitration of Tetraacetyldibenzylhexaazaisowurtzitane

Tetraacetyldibenzylhitane (TADBIW) was subjected to debenzylation by nitrosating with inorganic materials available commercially to synthesize tetraacetyldinitrosohexaazaisowurtzitane (TADNSIW). TADNSIW was purified, and its structure was determined by FTIR, 1H NMR, MS and element analysis. The debenzylation reaction of TADBIW gave quantitative benzaldehyde as a by-product. This indicates that the reaction produces an imine cation as an intermediate. Hexanitrohexaazaisowurtzitane (HNIW) was prepared from unpurified TADNSIW with the yield over 96.0 % and the purity more than 98.0 %. And the mechanism of the reaction from TADNSIW to HNIW is proposed to be oxidation of nitroso and nitration of acetyl on the molecule of TADNSIW, This reaction system involved is simple, and the reaction can complete within a short time and under mild conditions. The product can be easily to separate and the waste disposed readily.     

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.     

Parameter Identification for the Valve Control Cylinder System of a Hydraulic Manipulator

In mechanical, hydraulic and electronic systems, the determination of system parameters is often challenging because liquid parameters often change significantly, due to variations in working and environmental conditions. Therefore, it is of significant practical importance to identify those parameters through experimental procedures. A systematic approach to identifying parameters in the valve controlling cylinder system of hydraulic manipulators is provided. It first derives the transfer function of the system, and then uses P control of PID control to predict system parameters. The predicted parameters are further validated using PID control. The prediction through simulation using MatLab language is utilized, which agrees well with experimental results.     

Three-dimensional Numerical Simulation of Combustion Field in the Combustion Chamber

In order to study the effect of rotation on the combustion in the underwater vehicle, a two-phase turbulent combustion process is described with Reynolds stress turbulence model, eddy-dissipation turbulent combustion model, P-1 radiation model and particle tracking model of liquid. The flow in the rotating combustion chamber is simulated at two different working speeds, 0 r/min and 1 000 r/min by Fluent software. The temperature, gas velocity, static pressure of wall and fuel concentration are computed and compared. The results show that the combustion in rotating combustor is faster and more effective.     

Software Communication Architecture Implementation and Its Waveform Application

This paper attempts to do a research on the development of software defined radio（SDR） based on software communication architecture（SCA）. Firstly, SCA is studied and a whole reference model of SCA3.0 core framework （CF） is realized; Secondly, an application-specific FM3TR waveform is implemented on the platform of common software based on the reference model; Thirdly, from the point of view of real-time performance and software reuse, tests and validations are made on the above realized CF reference model and FM3TR waveform. As a result, the SCA-compliant SDR has favorable interoperability and software portability and can satisfy the real-time performance requirements which are not too rigorous.     

Dynamic Simulation of the Tank Gun Recoil Response

By using the ATV module of MSC. ADAMS, the dynamic simulation of recoil response of tank gun is analyzed.How the recoil force affects the bodywork and the suspension during gun firing, as well as the changing status of the gun muzzle‘s velocity are gained. All results and analyzing methods are offered for the designing basis of optimizing tank vehicle-gun match. The constructive exploration is beneficial to improving the general capability of tank.     

Survey of Controllable Suspension System for Off-road Vehicles

The controllable suspension system can improve the performances of off-road vehicles both on road and cross-country. So far, four controllable suspensions, that is, body height control, active, semi-active and slow-active suspensions, have been developed. For off-road vehicles, the slow-active suspension and the semi-active suspension which have controllable stiffness, damping and body height are more appropriate to use. For many years, some control methodologies for controllable suspension systems have been developed along with the development of modern control theory, and two or more original control methods are integrated as a new control method. Today, for military or civilian off-road vehicles, the R&D of controllable suspension systems is ongoing.     

A Robust Algorithm for Watermarking 2D Vector Maps with Low Shape-Distortions

The technique of watermarking has been introduced into 2D vector maps for many potential applications such as protecting the copyright of important GIS （geographical information system） data and tracing the data source of military maps. In most previous works, although the validity of the map data could be preserved during the embedding procedure, the shape-distortions of the map elements are usually neglected which would tend to degrade the invisibility of the watermarking schemes. A shape-preserving algorithm for watermarking 2D vector maps is presented in this paper. A 1D distance sequence extracted from the original map is adopted as the cover data instead of 2D coordinates. A watermark bit is represented by changing the distributions of the cover data. The embedding procedure induces lower shape-distortions than in former works. Experimental results indicate better invisibility of the proposed scheme, as well as its robustness to certain attacks such as map simplification, interpolation, additive noise and most geometric transforms.     

Finite Element Analysis of Fretting Behavior Between an Engine Cylinder Block and a Main Bearing Cap

The finite element analysis of the fretting behavior between a cylinder block and a main bearing cap is presented. The stresses, relative fretting slip, fretting friction work parameter W and crack initiation location parameter G on the fretting contact surface of the cylinder block are obtained and analyzed. It shows that the fretting fatigue problem of the cylinder block can be quantitatively explained by W or G. The effects of pretightening force, friction factor and material combination of the cylinder block and the main bearing cap are studied. The computational results indicate that the fretting fatigue of the cylinder block can be allayed by increasing the elastic modulus of the cylinder block, but not by changing the other two factors.     

An Efficient Key Agreement Framework to MANET

Protocols for key management are compared and evaluated from the point of view on mobile ad hoe networks （MANET）. The issues of fault-tolerance and efficiency of key distribution protocols for group communications in MANET are addressed. Most key distribution protocols existing today are primarily designed for wlre-line networks. These protocols either fail to work as intended or cannot work at all when they are applied to the demanding environment of MANET. Parameters and performance of different protocols are analyzed, and then a fiat is given out, on which new protocols or existing ones are designed and modified, so that they can be robust, scalable and efficient in MANET.