一种联邦卡尔曼滤波渐变型故障容错方法

具有良好的容错性是组合导航系统的基本要求。组合导航系统易于完成突变型故障的检测与容错,对渐变型故障的检测与容错则较为困难。文中以联邦卡尔曼滤波为组合导航系统状态估计方法,针对渐变型故障,提出了观测品质的概念及其模糊评估方法,应用观测品质进行了导航系统的渐变型故障检测,利用观测品质构成局部滤波器估计均方误差阵的修正矩阵,设计了组合导航系统智能自适应渐变型故障容错方法并完成了仿真运算。     

固冲组合发动机进气道设计

简要地介绍了固体火箭-冲压组合发动机进气道设计思想,叙述了后置旁侧进气道突扩的特点,由于气流的拐弯、突扩和掺混,进气道总压恢复系数辐度下降。因此过于讲究进气道本身型面设计是完全没有必要的,而尽可能减小外阻却是极为重要的。 固冲组合发动机多用于加速式地空弹,这就需要增加接力点附近的推力,因此应考虑采用超额定工作进气道,增大流量以提高地空弹加速式冲压型发动机和导弹性能。 文中对后置旁侧气道攻角适用范围以及大攻角进气道性能进行了讨论,因为这是组合发动机用于地空弹和反辐射弹需要解决的突出问题,加大组合发动机攻角范围是当前急需解决的技术关键。     

MULTI-CONTROLLER STRUCTURE OF SUPERMANEUVERABLE AIRCRAFT

Supermaneuver flight is often operated withhigh angle- of- attack and high angular rates.Su-per- maneuver flight cannot be controlled by aconventional gain- scheduled controller but canbe controlled by using a nonlinear dynamic- in-version controller[1～ 3] .　　 This paper presents a method to use twokinds of controllers,nonlinear dynamic- inver-sion and conventional gain- scheduled con-trollers,in a flight control system.The nonlin-ear dynamic- inversion controller is used to con-trol superm…     

Optimum FFT-based frequency acquisition with application toCOSPAS-SARSAT

In the case of a single sinusoid or multiple well-separated sinusoids, a coarse estimator consisting of a windowed Fourier transform followed by a fine estimator which is an interpolator is a good approximation to an optimal frequency acquisition and measurement algorithm. The design tradeoffs are described. It is shown that for the fine-frequency estimator a good method is to fit a Gaussian function to the fast-Fourier-transform (FFT) peak and its two neighbors. This method achieves a frequency standard deviation and a bias in the order of only a few percent of a bin. In the case of short-time stationarity, for a moderate number of averages and for an adaptive threshold detector, only between 0.5 and 1 dB is lost when averaging is traded off for FFT length, in contrast to the asymptotic result of 1.5 dB. The COSPAS-SARSAT satellite system for emergency detection and localization is used to illustrate the concepts. The algorithm is analyzed theoretically, and good agreement is found with test results     

基于PCC的航空机轮静载荷试验台控制系统研究

设计了一种基于PCC和工控机组成的航空机轮静载荷试验台控制系统,充分利用了PCC可靠性高、扩展性好等的优点,构建了一个性能稳定、功能强大的机轮载荷控制系统,有效提高了控制系统的自动化水平,大大降低了电气控制系统的复杂程度,使得航空机轮静载荷试验台控制系统能够可靠地完成机轮静态性能检测任务.     

考虑多类维修优先权的多级维修供应系统库存控制

备件筹措与保障站点的维修能力和故障件维修机制密切相关。在经典VARI-METRIC模型上,拓宽了模型中"无限维修总体"和"先到先修"的假设条件,基于排队理论,考虑维修优先权对维修过程的影响,对故障件的维修周转时间进行了修正,建立了具有多类维修优先权的备件初始库存优化模型。构造了多站点优先权分配的目标函数,采用智能优化算法对优先权分配方案进行了优化;根据所得方案,采用边际优化算法进行了备件库存优化,提出了采用智能优化算法和边际优化算法对优先权分配方案和备件库存进行分步优化的方法,并开展了算法复杂度分析。算例分析表明,考虑优先权的备件配置方案在满足各项保障效能指标的同时,显著降低了备件购置费用;分步优化的方法在有效降低运算时间提高计算效率的同时保持了一定的计算精度。提出的模型和优化方法能够为装备保障人员制定合理的保障方案提供决策支持。     

基于弹簧质量模型的复合材料螺接修理载荷传递计算方法

复合材料螺接修理具有操作简便,对连接件表面处理的要求不高,施工快速、性能可靠等优点,在复合材料的临时修理、尤其是战伤修理中应用较为广泛。然而其修理设计过程较为复杂,难以满足工程快速定参的需要。在螺接接头弹簧质量模型的基础上,针对蒙皮和补片等宽的情况,提出了一种复合材料螺接修理结构载荷传递比例计算方法。通过引入载荷按刚度分配的原则对模型进行修正,将模型进一步推广到蒙皮宽度大于补片宽度的情况。然后讨论了模型中不同弹簧刚度的计算方法。给出了采用细观力学方法以及均匀化方法等计算含损伤蒙皮等效刚度的计算方法,推导得到了规则排列多列螺栓连接中各排螺栓等效刚度的计算方法,并证明该刚度满足叠加原理。最后,以含圆形损伤孔的复合材料蒙皮板的螺接修理问题为例,对模型进行了考核,并与有限元法（FEM）预测结果进行了对比。结果表明：模型预测结果与有限元结果吻合较好,预测误差最大为7.7%。采用该模型可以高效、准确地实现复合材料螺接修理的分析设计。     

An innovative approach for integrated airline network and aircraft family optimization

The determination of optimal aerial transport networks and their associated flight frequencies is crucial for the strategic planning of airlines, as well as for carrying out market research, to establish target markets, and for aircraft and crew rostering. In addition, optimum airplane types for the selected networks are crucial to improve revenue and to provide reduced operating costs. The present study proposes an innovative approach to determine the optimal aerial transport network simultaneously with the determination of the optimum fleet for that network, composed of three types of airplanes (network and vehicle integrated design). The network profit is maximized. The passenger’s demands between the airports are determined via a gravitational model. An embedded linear programming solution is responsible for obtaining potential optimal network configurations. The optimum fleet combination is determined from a database of candidate aircraft designs via genetic algorithm. A truly realistic airplane representation is made possible thanks to accurate surrogate models for engine and aerodynamics is adopted. An accurate engine deck encompassing a compression map and an innovative engine weight calculation besides an aerodynamical artificial neural network module enable a high degree of accuracy for the mission analysis. The proposed methodology is applied to obtain the optimum network comprised of twenty main Brazilian airports and corresponding fleet.     

Sensor Optimization Selection Model Based on Testability Constraint

Sensor selection and optimization is one of the important parts in design for testability. To address the problems that the traditional sensor optimization selection model does not take the requirements of prognostics and health management especially fault prognostics for testability into account and does not consider the impacts of sensor actual attributes on fault detectability, a novel sensor optimization selection model is proposed. Firstly, a universal architecture for sensor selection and optimization is provided. Secondly, a new testability index named fault predictable rate is defined to describe fault prognostics requirements for testability. Thirdly, a sensor selection and optimization model for prognostics and health management is constructed, which takes sensor cost as objective function and the defined testability indexes as constraint conditions. Due to NP-hard property of the model, a generic algorithm is designed to obtain the optimal solution. At last, a case study is presented to demonstrate the sensor selection approach for a stable tracking servo platform. The application results and comparison analysis show the proposed model and algorithm are effective and feasible. This approach can be used to select sensors for prognostics and health management of any system.     

RESEARCH ON THE 3-AXES ROUGH MILLING OF MULTI-SURFACES

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一种基于LMI的航空发动机输出反馈PI控制

基于LMI(LinearMatrixInequality,线性矩阵不等式),提出一种航空发动机PI输出反馈控制器设计方法。利用被控对象中控制向量2范数上界的限制,提出了一种改进ILMI(IterativeLMI)算法,用于解决控制受约束的航空发动机PI控制器的一种LMI描述求解问题。以某型双转子涡喷发动机为被控对象,基于LMI进行了PI输出反馈控制器的设计,并分区域在飞行包线进行了航空发动机控制系统仿真验证。结果表明,所得控制器满足预期设计要求,同时具有一定鲁棒性。     

非结构混合网格自适应并行技术

计算流体力学（CFD）模拟实际工程问题所采用的网格规模可达千万量级，并行技术是减少计算时间的有效方法。耦合流场信息的网格自适应技术能有效动态优化计算网格，被NASA视为一项亟待发展的CFD关键技术。混合网格自适应系统包含网格分布优化、表面网格投影和空间网格匹配等关键技术。针对以上3项关键技术分别建立了高效的并行算法。首先，提出了"先唯一后同一"的两步法策略实现了网格单元分布优化过程的并行相容性；其次，基于局部曲面拟合思想，实现了曲面重构和新增物理网格点投影的完全并行；再次，提出了空间网格匹配技术的半并行算法，快速解决了网格单元交错问题。为了提高后续流场计算的并行效率，发展了基于并行重分区-网格数据迁移方法的动态负载平衡技术，并采用圆柱激波流场自适应模拟对动态负载平衡技术进行初步验证。最后，采用三角翼自适应加密测试了自适应系统的并行效率。结果表明，建立的混合网格自适应系统并行效率较高，且相比流场求解耗费总时间的比例低于1%。     

航空发动机试车三分钟事件记录与回放

航空发动机试车计算机辅助试验系统中开发三分钟事件记录与回放功能可以为事后的分析提供数据依据。本文着重研究了事件模型的建立的一般方法,讨论了数据记录与回放的方法,最后给出了所采用的数据结果。根据本文所论述的方法,实现了该功能并已投入了某型航空发动机试车实验使用。      

整体叶盘数控砂带磨削技术及其试验

针对航空发动机整体叶盘结构复杂、材料难加工,铣削加工后粗糙度无法达到设计要求,铣削纹理明显,目前的手工抛光难以满足整体叶盘表面质量和型面精度要求的现状,提出了整体叶盘数控砂带磨削技术及其工艺试验。概述了整体叶盘砂带磨削研究进展,分别从新型砂带磨削技术和自适应砂带磨削技术等方面阐述了整体叶盘全型面数控砂带磨削技术。介绍了整体叶盘全型面数控砂带磨削试验装置及其数控磨削加工软件,利用该装置完成了4种不同级别的整体叶盘精密磨削加工试验。结果表明:整体叶盘磨削后,表面粗糙度小于0.4μm,型线精度小于0.05mm,同时型面精度一致性显著提高。     

基于PH曲线的数控拐角过渡方法

 为了减弱轨迹拐角处的向心加速度变化给加工带来的不利影响,使用五次PH曲线进行拐角过渡,在控制加工速度的同时对向心加速度进行控制。通过对拐角处连接情况的分析,确定了连接PH曲线中的参数计算方法。在拐角前后使用S加减速进行加工,以保证直线、圆弧轨迹加工中的平稳;在拐角连接区域内使用基于曲率的速度模型,通过对拐角前后S加减速和拐角速度的连接,使拐角前后的速度更加连续,得到平滑的速度曲线;通过拐角处的加速度和弓高误差的限制,计算平稳的加工速度。结果表明,使用五次PH曲线进行拐角过渡的误差小于7.4 μm,能够满足加工需要,同时,拐角处的向心加速度变化更加平稳。将拐角前后的S加减速和拐角区域内速度连接后,得到了平滑的速度曲线。     

直升机总体参数优化设计

根据直升机的飞行性能、稳定性、发动机和重量的要求,建立优化的分析模型,应用计算机和最优化技术求解,得到满足直升机设计准则的最佳总体设计方案。本方法也可用于对已有型号的总体参数分析和参数敏感性分析。通过算例和新机设计中的应用表明,本方法对直升机总体参数选择是行之有效的。     

Effect of a Few Dominant Specular Reflectors Target Model Upon Target Detection

Some data indicate that aircraft targets viewed from certain aspects are well modeled as consisting of a few specular reflectors. The effect of a simplified form of this target model upon radar detection performance for two different waveforms has been analyzed. The signal-to-noise ratio (SNR) required for detection as a function of waveform bandwidth for a conventional-single-channel waveform and for a four-channel frequency diversity waveform is evaluated. It is shown that for either waveform there is an optimum bandwidth to minimize the SNR required for detection. In addition, the single-channel minimum is less than the four-channel minimum. The best performance occurs for the single-channel waveform when the waveform bandwidth just resolves the individual reflectors. For typical targets, this bandwidth is of the order of 35 to 75 MHz. It is also shown that only a 0.8-dB loss relative to this minimum is incurred when using a four-channel narrow bandwidth waveform.     

Optimum Realizable Continuous Range Estimation

The ability to detect the presence or absence of a target is no longer the fundamental design criterion when the vehicle to be tracked is cooperative. In spacecraft tracking or navigation systems, for example, emphasis is placed on post-acquisition performance. Therefore, classical radar theory and design techniques are not specifically applicable. On the other hand, there are optimization techniques for extracting the tracking data from noise that are more to the point. In particular, optimum demodulation theory is directed specifically to the problem of continuously extracting data from a nonlinear modulation process. In this paper, the tracking properties of a multitone PM ranging signal are reviewed and are shown to be nearly optimum for cooperative vehicles. An optimum, but nonrealizable, maximum a posteriori (MAP) continuous estimator of range is derived for this signal. The linearized model of this receiver is the optimum nonrealizable Wiener filter for the data. Interpretation of this optimum nonrealizable estimator leads to a receiver design that is both practical and intuitively satisfying. With the aid of post-detection processing in the Wiener-Hopf sense, almost optimum performance is obtained from the resulting receiver, above threshold.     

涡扇发动机内外函回热分析

对吴仲华教授提出的航空涡扇发动机改为陆用输出轴功的一种最安全可靠办法-将外函空气由内函动力透平排气回热后也输出轴功,进行了基本的热力循环分析。按初步分析可知,此法宜用于函道比接近于1的总压比不太高的机组。按目前技术水平,采用此措施可以达到比“切顶”相对提高效率与功率10%左右。在我国有一定的应用前景。