二阶滑模控制算法在滑翔增程弹中的应用研究

滑翔增程是目前采用的较为有效的一种弹箭增程技术,对滑翔增程弹进行控制,就要使弹丸在飞行过程中,能够尽可能地跟踪方案弹道。利用无陀螺捷联惯性测量装置,实时解算弹丸滑翔飞行过程中的实际飞行姿态和弹道参数,与方案弹道中的理想飞行参数进行比较,其偏差信号构成控制指令。将增程弹的弹道分为升弧段和降弧段:升弧段为无控飞行;降弧段采用二阶滑模控制算法设计控制器。通过鸭式舵控制弹丸飞行实现增程,获得了较高的指令跟踪性能,对滑翔增程弹的设计具有一定的参考价值。     

求解滑翔增程弹较优舵偏角方法

文中阐述了滑翔增程弹的飞行过程,建立了滑翔弹在纵向平面内的弹道模型,分别采用序列二次规划法和最大升阻比法,对俯仰舵面的较佳控制过程进行了分析,仿真计算表明,序列二次规划法优化得到的俯仰舵偏角规律较优,适用于滑翔增程弹求解俯仰舵偏角的后期优化工作;最大升阻比法所求得的俯仰舵偏角规律较差,但其方法及求解过程简单,适用于滑翔增程弹前期的论证工作.     

滑翔增程弹箭滑控段弹体运动模式对增程效率的影响

增程技术是弹箭技术重点发展方向之一,而滑翔增程是目前采用的较为有效的ー种弹箭增程技术。阐述了滑翔增程弹箭的飞行过程,建立了滑翔增程弹箭的滑翔段弾道模型,在滑翔控制段弹体分别采用俯仰滑翔飞行和旋转滑翔飞行,分析了在滑'翔控制段弹体的两种运动模式对弹箭增程效率的影响。仿真结果表明：在滑翔控制段弹体釆用俯仰滑翔飞行,增程效率高,但在滚转控制过程中控制系统复杂,对舵机的要求高;在滑翔控制段弹体采用旋转滑翔飞行,增程效率较低,但整个控制过程中控制系统简单,对舵机的要求低。     

滑翔增程弹方案弹道特性的研究

阐述了滑翔增程弹的飞行原理，建立了滑翔增程弹的方案弹道模型，通过数值计算得到了滑翔增程弹方案弹道的形状特征、弹丸飞行速度沿全弹道的变化规律和最大射程角的特点，对今后进行滑翔增程弹的设计有重要促进作用。     

无翼式布局制导火箭弹俯仰操纵气动特性

为了研究某无翼式布局制导火箭弹进行俯仰操纵时非线性气动特性对弹箭操纵性的影响,通过模型风洞试验和数值计算相结合的方法,分析了不同马赫数、舵偏角和攻角等因素对该火箭弹气动特性的影响。对模型进行超声速风洞试验,试验结果表明,俯仰操纵负舵偏角时俯仰力矩系数导数随攻角先增大后减小,正舵偏角时俯仰力矩系数导数随攻角先减小后增大。采用ANSYS FLUENT对不同工况下该弹气动特性进行数值计算,计算结果表明,得到的俯仰力矩与风洞实验结果吻合较好,最大误差仅为4.6%。各部件气动特性分析结果表明:弹身的压心在负舵偏角时前移,正舵偏角时后移;上尾舵受弹身干扰影响法向力效率降低;负舵偏角时下尾舵的法向力系数导数随攻角减小,正舵偏角时下尾舵的法向力系数导数随攻角增大;各部件共同作用下弹箭气动特性呈非线性。     

滑翔增程弹气动特性分析

针对滑翔增程弹在有弹翼和无机翼两种情况下，气动特性进行了计算、分析和比较。计算结果表明，有弹翼时滑翔增程弹的升阻比与无弹翼时的升阻比相比大得多，因此滑翔增程弹能够较好的达到滑翔增程的目的。     

旋转稳定二维弹道修正弹在固定舵作用下的角运动特性研究

为研究旋转稳定二维弹道修正弹在固定舵作用下的攻角及速度运动特性,建立了复数形式的角运动方程。推导了固定舵匀速转动时攻角的强迫运动解及固定舵产生阶跃激励时攻角的瞬态、稳态响应解析解;推导了有控时平均速度偏角的解析解,导出了平均偏角的幅值和相位角与固定舵参数的关系;提出了旋转稳定二维弹道修正弹在固定舵作用下的飞行稳定性条件。结果表明:二维弹道修正弹无控时应避免共振,有控时应限制攻角最大增量及平衡攻角幅值;有控时平均偏角的相位角较固定舵滚转角提前一个前置角。研究结果对旋转稳定二维弹道修正弹的飞行稳定性设计及制导方法研究提供了参考。     

钻石背弹翼气动特性风洞实验研究

采用模块化方法设计了ー组具有“钻石背”弹翼的风洞实验模型,进行了六分量测カ实验,实验马赫数范围为Ma=0.4~0.8,攻角范围为-2°?12°俯仰控制舵偏角为-5°.实验结果表明：“钻石背”弹翼能提供较大的升力,具有“钻石背”弹翼的飞行器升阻比可达5以上,有很强的滑翔增程能力,适用于无动カ制导炸弹的滑翔增程;攻角>6°时,升力随攻角变化曲线的当地斜率迅速降低,应按最大升阻比选择滑翔飞行的攻角。     

滑翔增程弹弹道特性分析

滑翔增程是目前采用的较为有效的ー种弹箭增程技术。阐述了滑翔增程弹的飞行过 程,按其飞行过程将整个飞行弹道分为三段,并分别建立了各段的弹道模型;研究了整个飞行弹道 的特性,得到滑翔弹弹道与常规弹道在升弧段是一致的,在降弧段上则出现了较大的差別;在滚控 段采用“小步走”的控制策略,在滑控段采用开环控制。仿真计算表明：控制方法可行,计算结果与 设计思想一致,对滑翔增程弹的研制有一定的参考意义。滑翔增程是目前采用的较为有效的ー种弹箭增程技术。阐述了滑翔增程弹的飞行过 程,按其飞行过程将整个飞行弹道分为三段,并分别建立了各段的弹道模型;研究了整个飞行弹道 的特性,得到滑翔弹弹道与常规弹道在升弧段是一致的,在降弧段上则出现了较大的差別;在滚控 段采用“小步走”的控制策略,在滑控段采用开环控制。仿真计算表明：控制方法可行,计算结果与 设计思想一致,对滑翔增程弹的研制有一定的参考意义。     

带鸭舵滑翔增程炮弹飞行弹道研究

文中针对鸭式布局的滑翔增程炮弹的飞行弹道特性,通过动力学分析,建立了滑翔增程炮弹的各飞行弹道段的弹道模型和控制模型,数值分析给出了滑翔增程弹飞行速度变化规律、最大射程角以及滑翔增程炮弹的滚转控制段与滑翔控制段的弹道特性,研究结果为鸭式布局滑翔增程炮弹的弹道设计提供了理论基础。     

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.