Digitized mapping: the key to achieving a common command and control picture

One of the main goals in transforming the Army is the process of moving away from the use of paper maps and grease pencils into more embedded and computer-oriented forms of command and control. There are currently many weapons platforms trying to achieve this function; however, each platform is developing their own solution to meet individual needs. The Army as a whole needs to standardize on a single path forward to ensure that all systems can communicate across the digitized battlefield, allow for each platform to have a "common picture," and promote software reuse across the Army. Once this "common picture" is achieved, the armed forces will have the information needed to continue domination of the battlefield.     

Implementing Aircraft Identification Schemes by Public Key Cryptosystems

The use of public key cryptosystems for identification purposes has already been suggested. The practical aspects of using such systems for aircraft identification are discussed. It is shown that the digital signature property is not mandatory for implementing an identification procedure. It is then shown how public key distribution systems can be used for identification purposes. The technical difficulties in implementing an identification scheme are finally discussed with possible solutions offered.     

Facing harsh realities--in space, air, and war

Current legislative activity in Washington includes plans for hearings and proposed changes to NASA after the publication of the Columbia Accident Investigation Board report in August, 2003. Also reviewed are legislative interest in airline safety and armed forces expansion.     

Safety testing of lithium ion batteries for navy devices

Lithium ion battery technology is being introduced into power supplies used by our armed forces for a variety of applications. In many cases, the same cells and design parameters that support commercial battery packs are being used in military battery packs. This approach is expected to result in a major decrease in the total life cycle cost of the equipment these batteries support. On June 13, 1991, NAVSEA issued INST9310.1B1, which states that all lithium battery powered equipment must undergo safety evaluation and approval prior to fleet use. This safety program governs a process whereby approvals are issued for lithium batteries to be used in specific equipment on ground facilities, surface combatants, air combatants, and/or submarines. The Naval Ordnance Safety and Security Activity (NOSSA) manages the program. The chief technical advisors are Code 644 at NSWC Carderock Division and Code 609A at NSWC Crane Division. This paper describes three battery designs that incorporate lithium ion technology, and the results of battery safety tests conducted in accordance with navy requirements.     

Adaptive model architecture and extended Kalman-Bucy filters

In radar systems, extended Kalman-Bucy filters (EKBFs) are used to estimate state vectors of objects in track. Filter models accounting for fundamental aerodynamic forces on reentry vehicles are well known. A general model structure accommodating the dynamics of reentry vehicles in both exoatmospheric and endoatmospheric flight is presented. The associated EKBFs for these various models are described and the resulting associated parameter estimation and identification problems are discussed. The effects of position, velocity, drag, and aerodynamic lift are described within a nested set of EKBF models     

生长军官学员学风评价研究

根据军队院校教育的特点和规律构建了生长军官学员学风评价的指标体系,提出了学风评价的数学模型,依据指标体系和数学模型对某军校进行了学员学风实测,在此基础上进行了分析研究。     

武装直升机横航向增控增稳系统鲁棒性研究

武装直升机横航向增控增稳系统可看作是２输入５输出的多变量控制系统,多变量控制系统的鲁棒性可用稳定裕度作为衡量标准。利用矩阵奇异值分解的方法,计算武装直升机横航向ＳＣＡＳ的稳定裕度,来评判所设计系统的鲁棒性。该方法获得的满足鲁棒性所要求的裕度指标,为我国军用直升机飞行品质规范的修订提供了依据。     

武装直升机红外成像仿真

虚拟仿真以其低成本、短周期、高质量的特点,逐渐成为复杂环境下红外成像制导武器设计分析、验证和评估的主要手段之一。以某武装直升机目标为对象,首先利用基于航空发动机物理模型的方法,通过全尺寸几何建模、计算蒙皮、尾喷和羽烟等主要红外辐射源的流场和温度场,利用灰度等级描述红外辐射信息,生成不同视向角下的近场红外辐射亮度显示,并存储形成数据库。然后根据具体使用时的条件从数据库中调用,按照距离进行大气衰减,最终形成视点处的红外辐射亮度显示。实验结果证明,算法生成的武装直升机红外图像真实感强,实时性好,可用于红外成像制导导弹仿真和夜航模拟训练系统的红外视景显示,具有一定的军事参考价值。     

一种基于响应信息的整体叶盘结构失谐识别方法

以谐调叶盘有限元模型解析模态和真实失谐结构的稳态响应作为基础信息,提出一种整体叶盘结构失谐识别方法。该方法基于公称模态子集（SNM）降阶技术,降低了识别过程的计算花费以及对基础信息量的要求;采用子矩阵型技术使得失谐参数定义更加自由,并使得该方法具有模型修正的功能;直接利用实测的稳态响应数据作为输入参数,并且不需要施加在结构上的外力信息,提高了基础数据可靠性并有效降低了实际测量的难度。最后以一个整体叶盘结构的仿真分析证明了该方法的有效性。     

CESM-a new category of radar ECCM

Radar ECCM techniques are well known. Heretofore the listed ECCM effects have generally been to counteract the effects of ECM. This approach is one of attempting to cure an illness, rather than preventing it. Modem ECM systems usually include an ESM receiver to detect the radar signal, identify it by its emission characteristics, assess its importance, select the proper ECM, and signal to initiate ECM. If the ESM receiver detection of the radar signal can be delayed/denied, or the identification be confused, either the wrong ECM may be applied, or delayed. The radar may thus not be confronted with timely, proper ECM. Radar operation may therefore be possible. This paper introduces and defines CESM, a new category of radar ECCM. There are two principles of CESM-those which delay/deny ESM receiver detection, and those which confuse/impede signal identification. Illustrative examples of CESM techniques/operating techniques are given. It is shown that many CESM techniques may have multiple roles by impeding detection, impeding identification, and also diluting effects of ECM     

考虑模型抖振力跨向不完全相关性效应的气动导纳识别

首先通过考虑节段模型上抖振力跨向不完全相关性效应推导了节段模型风洞试验中作用在模型断面上的分布抖振力谱和由底支式天平测到的模型总抖振力谱之间的关系。然后,以准平板断面为例,进行了格栅湍流场节段模型的测力和同步测压试验,获得了模型总抖振力谱以及模型抖振力跨向相关性函数。接着,采用等效导纳法以及抖振力自谱和抖振力脉动风速交叉谱综合残量最小二乘法分别识别了准平板节段模型等效气动导纳和六分量气动导纳,讨论了模型抖振力跨向不完全相关性效应对气动导纳识别结果的影响,并把识别得到的准平板断面气动导纳与平板断面气动导纳的理论结果——Sears函数进行了比较。结果表明：忽略抖振力跨向不完全相关性效应（即假设节段模型分布抖振力沿跨向完全相关）而直接采用平均抖振力作为断面上分布抖振力的传统方法会导致气动导纳识别结果偏小,并且,其偏小程度会随着频率的增加而增加;此外,相对于抖振升力和扭矩相关的气动导纳分量而言,由于抖振阻力的跨向相关性比抖振升力和扭矩的跨向相关性显得更弱,因此抖振力跨向不完全相关性效应对阻力相关气动导纳分量识别结果的影响更大;利用识别得到的六分量气动导纳反算的作用在模型上的分布抖振力谱与试验中实测结果非常接近,经抖振力跨向不完全相关性效应修正后的竖向脉动风速对应的升力和扭矩气动导纳分量的识别结果与Sears函数也比较接近,从而验证了用于六分量气动导纳识别的自谱-交叉谱综合最小二乘法的可靠性。     

直升机超低空突防辅助系统关键技术研究

介绍了直升机超低空突防辅助系统的组成部分及关键技术,研究表明,将现有超低空突防技术应用于直升机,有效降低直升机的飞行高度,实现直升机超低空贴地飞行,可以大大提高武装直升机攻击的突然性、精确性和多样性,提高武装直升机的空战能力以及远程突袭的安全性,也可以提高民用直升机的任务成功率和安全性。具有非常广阔的应用前景。     

基于PCI总线接口的SD主控制器的设计与实现

SD卡已在消费型电子产品中得到了广泛应用,在显示控制系统中如何实现对SD卡的支持也变得很重要,而目前在机载计算机中占主流的PowerPC微处理中没有集成SD主控制器,因此研究和实现在PowerPC模块中对SD卡的读写访问就显得很有意义。在分析SD主控制器规范的基础上,采用功能模块化的方法,设计和实现了基于PCI总线接口,支持DMA传输的SD主控制器。测试结果表明,该SD主控制器数据传输稳定,并且具有硬件逻辑方便移植、重构的特点,可应用于PCI总线接口的嵌入式系统中。     

基于小波神经网络辨识的PID神经MRAC研究

提出了一种基于小波神经网络辨识的PID神经网络模型参考自适应控制方法。该方法采用小波神经网络作为辨识器,PID神经网络作为控制器在线调节。由于小波变换具有良好的时频局部特性,神经网络具有强大的非线性映射能力,自学习、自适应等优势,采用规范正交的小波函数作为神经网络的基函数构成小波神经网络,该网络兼有小波函数的紧支性、波动性以及神经网络的非线性映射能力,自学习、自适应能力等优点,仿真结果表明用该方法构成的控制系统收敛速度快,逼近精度高,鲁棒性好,优于一般的BP网络控制。     

采用工作模态识别法进行模态分析

对于一些大型工作结构 ,有时很难测得输入信号 ,只能单独利用实测响应数据进行工作模态识别。本文针对工程实际中的这一情况 ,首先利用响应间互相关函数同脉冲响应函数在表达形式上的相似性 ,推导出了多参考点时域工作模态复指数法 ,继而又从响应间的互相关函数入手 ,推导出了多参考点频域工作模态识别法。最后采用一飞机模型对这两种方法进行了试验验证 ,并将所得结果做了对比分析 ,结果表明 ,两种多参考点方法都能较有效地单独从实测响应数据提取结构的模态参数 ,且频域工作模态识别法比时域工作模态复指数法识别精度更高。     

Identification of nonlinear flight dynamics: theory and practice

This article presents an innovative time-domain nonlinear mapping-based identification method. The method reported is applied to identify the unknown parameters of multivariable dynamic systems which are mapped by nonlinear differential equations. A systematic identification method is introduced, and a novel algorithm is developed using nonlinear error maps. An analysis of parameter convergence is provided and the regions of convergence can be found using the second method of Lyapunov. Innovative nonquadratic Lyapunov functions are designed and used. Analytical and numerical studies are performed to illustrate and validate the identification concept. The unsteady flight of a high-alpha aircraft in the longitudinal axis is chosen as a nonlinear case study. The unknown parameters are identified. Simulation results show that the model dynamics match the experimental data. The reported example demonstrates that the time-domain nonlinear mapping-based identification method ensures robustness and reduces major shortcomings in stability, convergence, and computational efficiency compared with other algorithms available     

采用频域多参考点模态识别法进行工作状态下的模态识别

 针对工程实际情况,从实测响应间的互相关函数入手,推导出适用于工作状态下的频域多参考点模态识别法,然后采用一飞机模型对该方法进行了试验验证。     

Generalized Kutta–Joukowski theorem for multi-vortex and multi-airfoil flow(a lumped vortex model)

For purpose of easy identification of the role of free vortices on the lift and drag and for purpose of fast or engineering evaluation of forces for each individual body,we will extend in this paper the Kutta–Joukowski(KJ) theorem to the case of inviscid flow with multiple free vortices and multiple airfoils. The major simplification used in this paper is that each airfoil is represented by a lumped vortex,which may hold true when the distances between vortices and bodies are large enough. It is found that the Kutta–Joukowski theorem still holds provided that the local freestream velocity and the circulation of the bound vortex are modified by the induced velocity due to the outside vortices and airfoils. We will demonstrate how to use the present result to identify the role of vortices on the forces according to their position,strength and rotation direction. Moreover,we will apply the present results to a two-cylinder example of Crowdy and the Wagner example to demonstrate how to perform fast force approximation for multi-body and multi-vortex problems. The lumped vortex assumption has the advantage of giving such kinds of approximate results which are very easy to use. The lack of accuracy for such a fast evaluation will be compensated by a rigorous extension,with the lumped vortex assumption removed and with vortex production included,in a forthcoming paper.     

金属橡胶-钢丝绳索型减摆阻尼器动力学建模与参数识别

研制了一种直升机旋翼系统金属橡胶—钢丝绳索减摆阻尼器,对其建立了非对称弹性黏性阻尼双折线迟滞恢复力模型,利用Fourier级数展开法对模型作线性化处理,基于力—位移迟滞回线中恢复力各个成分关于位移的对称关系,设计了一种参数分离的物理参数识别算法,数值仿真显示算法精度和抗噪性高,采用振幅3.2mm,频率3Hz的正弦位移载荷激励减摆器时,实测结果的计算表明模型及算法可用于实际研究。     

Corner-milling of Thin Walled Cavities on Aeronautical Components

This article presents a mathematical model of helical end-milling forces through experimental identification of the cutting coefficients and analyzes the changes of corner-milling forces under different conditions. In allusion to the corner-milling process, the relationship between working parameters and the corner coordinates is investigated by way of combination of tool tracing and cutting geometrodynamics. The milling parameters are optimized by changing the coordinates of tool center and working parameters without altering cutting forces. By applying the optimized parameters to milling practice, a comparison is made to show the improved product quality. Based on these optimized parameters, a finite element method (FEM) program is used to compute deformation values of a workpiece's corner, which evidences few effects that optimized parameters can exert on the corner deformation.