Multi-parameters uncertainty analysis of logistic support process based on GERT

The uncertainty analysis is an effective sensitivity analysis method for system model analysis and optimization. However,the existing single-factor uncertainty analysis methods are not well used in the logistic support systems with multiple decision-making factors. The multiple transfer parameters graphical evaluation and review technique（MTP-GERT） is used to model the logistic support process in consideration of two important factors, support activity time and support activity resources, which are two primary causes for the logistic support process uncertainty. On this basis,a global sensitivity analysis（GSA） method based on covariance is designed to analyze the logistic support process uncertainty. The aircraft support process is selected as a case application which illustrates the validity of the proposed method to analyze the support process uncertainty, and some feasible recommendations are proposed for aircraft support decision making on carrier.     

Multiple-Attribute and Multilevel Synthetic Evaluation Model and Its Application

On the basis of analyzing the flaws of present multiple-attribute and multilevel evaluation methods, concerning the problem of characteristics of the multiple-attribute and multilevel system s appraisal and the particular emphasis on the respective attributes in the evaluation process, as well as its relevance to the environment, an optimal attribute system is proposed, and the multiplicative analytic hierarchy process (MAHP) is used to obtain subjective weight coefficients and the objective weight coefficient evaluating method is given. The deviation between the index value of each level and the values of the same index of other levels are formulated, and an optimal model is gained, thus establishing the weight coefficients of the whole optimal attribute system. Furthermore, the detailed implementation procedure of this method is introduced. Besides, favorable results have been gained by applying the model to the practical problems of economic evaluation.     

EMMD-Prony approach for dynamic validation of simulation models

Model validation and updating is critical to model credibility growth. In order to assess model credibility quantitatively and locate model error precisely, a new dynamic validation method based on extremum field mean mode decomposition(EMMD) and the Prony method is proposed in this paper. Firstly, complex dynamic responses from models and real systems are processed into stationary components by EMMD. These components always have definite physical meanings which can be the evidence about rough model error location. Secondly, the Prony method is applied to identify the features of each EMMD component. Amplitude similarity, frequency similarity, damping similarity and phase similarity are defined to describe the similarity of dynamic responses.Then quantitative validation metrics are obtained based on the improved entropy weight and energy proportion. Precise model error location is realized based on the physical meanings of these features. The application of this method in aircraft controller design provides evidence about its feasibility and usability.     

基于UML的通用3D飞行仿真平台的设计与实现

一个能对不同飞行器进行仿真的综合性平台对飞行器建模和飞行控制算法设计等理论研究工作具有重要意义。采用基于UML的面向对象的程序设计方法,综合利用网络通信与3D视景仿真,数据库,模型库等技术,构建了基于局域网的分布式通用3D飞行仿真平台。通过为飞行器模型设计合适的接口,该平台可以适用于多种飞行器的仿真,大大减少了数据和代码的冗余,具有良好的飞行器通用性和功能扩展性。

Abstract：

Theoretical research on modeling and control of aircraft needs a platform to simulate and verify the correctness and accuracy.A distributed universal 3D flight simulation platform was designed based on UML Object Oriented modeling method,network communications,3D visual simulation,database and model base.This platform could be used for simulating various aircraft by well designed interface of aircraft models.The code and data redundancies are greatly reduced.The platform has a good aircraft universal availability and function augment ability.     

Conceptual design and RCS performance research of shipborne early warning aircraft

In order to improve the survivability of the aircraft,conceptual design and radar cross section（RCS） performance research are done. The CATIA software is used to design the 3D digital model of the shipborne early warning aircraft, and some measures are taken to reduce the RCS characteristics of the early warning aircraft at the same time. Based on the physical optics method and the equivalent electromagnetic flow method,the aircraft＇s RCS characteristics and strength distribution characteristics are simulated numerically, and compared with the foreign advanced shipborne early warning aircraft. The simulation results show that under the X radar band, when the incident wave pitching angle is 0？, compared with the foreign advanced shipborne early warning aircraft, the forward RCS average value of the conceptual shipborne early warning aircraft is reduced to 24.49%, the lateral RCS average value is reduced to 5.04%, and the backward RCS average value is reduced to 39.26%. The research results of this paper are expected to provide theoretical basis and technical support for the conceptual design and the stealth design of the shipborne early warning aircraft.     

Inspection interval optimization for aircraft composite structures with dent and delamination damage

The optimization of inspection intervals for composite structures has been proposed,but only one damage type,dent damage,has been addressed so far.The present study focuses on the two main damage types of dent and delamination,and a model for optimizing the inspection interval of composite structures is proposed to minimize the total maintenance cost on the premise that the probability of structure failure will not exceed the acceptable level.In order to analyze the damage characteristics and the residual strength of the composite structure,the frequency,energy,size,and depth of the damage are studied,and the situation of missing detection during the inspection is considered.The structural residual strength and total maintenance cost are quantified corresponding to different inspection intervals.The proposed optimization method relieves the constraints in previous simulation methods,and is more consistent with the actual situation.Finally,the outer wing of aircraft is taken as an example,and with the historical cases and experimental data,the optimization method is verified.The optimal inspection interval is shorter than the actually implemented inspection interval,and the corresponding maintenance cost is reduced by 23.3%.The result shows the feasibility and effectiveness of the proposed optimization method.     

Tool orientation planning for five-axis CNC machining of open free-form surfaces

For the geometry characteristics of open free-form surfaces, it is hard to consider global interference during the planning of feasible domains. Therefore, the optimal kinematic orientation of tool axis will no longer be confined to the boundary of feasible domains. In this paper, according to the principle demanding that the tool should be fitted to a surface as close as possible and relevant processing parameters, a feasible domain of tool orientation for each cutter contact is planned in the local feed coordinates system. Then, these feasible domains of the tool orientation are transformed into the same coordinates system of the machine tool by the inverse kinematics transformation. The linear equations based feasible domain method and Rosen gradient projection algorithm are used to improve the optimization process in precision and efficiency of the algorithm. It constructs the variation of tool orientation optimization model and ensures the smoothness of tool orientation globally. Simulation and analysis of examples show that the proposed method has good kinematics performance and greatly improves the efficiency.     

NSHV trajectory prediction algorithm based on aerodynamic acceleration EMD decomposition

Aiming at the problem of gliding near space hypersonic vehicle(NSHV)trajectory prediction,a trajectory prediction method based on aerodynamic acceleration empirical mode decomposition(EMD)is proposed.The method analyzes the motion characteristics of the skipping gliding NSHV and verifies that the aerodynamic acceleration of the target has a relatively stable rule.On this basis,EMD is used to extract the trend of aerodynamic acceleration into multiple sub-items,and aggregate sub-items with similar attributes.Then,a prior basis function is set according to the aerodynamic acceleration stability rule,and the aggregated data are fitted by the basis function to predict its future state.After that,the prediction data of the aerodynamic acceleration are used to drive the system to predict the target trajectory.Finally,experiments verify the effectiveness of the method.In addition,the distribution of prediction errors in space is discussed,and the reasons are analyzed.     

The Maximum Likelihood Method of Aerodynamic Parameter Identification

In this paper a method of aerodynamic parameter identification of vehicle, the maximum likelihood method, is introduced. The aerodynamic model of vehicle is identified and the basic equations using maximum likelihood method are established. After that, the simulation data is identified to verify the correctness of the mathematic model and identification method. Last, the practical flight data is identified and analyzed.     

Searching Multiple Structural Changes of Chinese Stock Market via GMDH

This paper analyzes multiple structural changes by GMDH （Group Meth- ods of Data Handling）, which have obvious advantages. Our method extends the model of Lumsdaine ＆ Papell[1] （1997）, and it could be applied to the case of more than two structural changes. Because of simultaneously considering every structural change of the hypothesis, it is likely to be of particular relevance in practice. And it can decrease large investigation costs by MATLAB programming. What is more, we can select the criterion value of F incremental statistic to control the significance of the breaks, based on kinds of investigation intentions. And the empirical evidences on Shenzhen Composite Index are presented to illustrate the usefulness of our method.     

三维空间中凸多刚体实时运动仿真

将计算机科学与理论力学相结合,介绍了多刚体运动仿真的步骤和方法。首先论述了单个及多个刚体的运动仿真步骤以及应用叠加原理计算合力及合力矩的方法。然后,针对刚体运动中的不同碰撞响应类型:碰撞接触与临时接触,分别建立不同的碰撞响应力学模型,前者运用恢复系数理论和动量、动量矩定理建立响应模型,后者通过分析刚体的受力和运动状态建立相应的动力学模型。最后,讨论了该方法的局限性以及适用的范围。     

对基于四元数的飞机本体运动模型的改进

现有的基于四元数的飞机本体运动方程没有完全消除欧拉角。本文推导了气流坐标系与机体坐标系的转换关系,尤其考虑了俯仰角为±90°时的情况。得到了以向量式表示的、完全消除欧拉角的飞机本体运动数学模型。该模型便于面向对象程序实现,并用于大姿态角飞行仿真。     

先进短距起飞垂直着陆飞机的建模与仿真研究

先进短距起飞垂直着陆(ASTOVL)飞行／推进综合控制技术的实现，需要进行大量的理论研究和仿真计算，以确定最优控制律。通过用全量非线性方程来描述的该类依靠气动舵面和推力矢量融合控制技术的飞机运动状态，建立了六自由度的飞机动力学数学模型。由于没有对刚体飞机数学模型和气动数据进行线性化处理，因而所建模型不仅能较全面地反映STOVL飞机的实际运行特性，而且具有较强的通用性。最后，以某型号STOVL飞机为背景，在MATLAB5．2／Simulink环境下研究和开发了飞行数字传真器，介绍了仿真软件的设计思想和程序架构，并通过数字仿真验证了该仿真器的正确性。     

雷达仿真中飞机编队平均反射截面的计算

研究中程警戒雷达仿真中飞机编队平均雷达反射截面的实时计算问题，首先运用经验曲线计算单架飞机处于不同姿态角时的平均雷达反射截面，其次当飞机在飞机编队中被遮挡时，考虑对飞机平均反射截面起主要作用的因素，飞机制投影面积，进气道，座舱和雷达舱，然后利用简化的飞机模型，计算飞机被遮挡与没有被遮挡时这些因素对反射截面贡献的比例，从而计算出被遮挡飞机的平均雷达反射截面，最后将飞机编队中各架飞机的反射截面相加，就可以得到飞机编队总的反射截面。     

基于本体的飞机舵面结构故障诊断方法

从系统工程的角度分析了飞机系统的复杂性,将飞机族的概念引入到飞机的本体建模中,并以舵面故障诊断过程为研究对象, 首先用Protégé建立了飞机本体的领域知识模型,然后将单故障和组合故障的诊断知识列为本体中的SWRL规则,最后利用 JESS推理出 新知识得出诊断结果,实现了用本体来选择修复方案的过程.该方法能够实现复杂系统的建模及故障诊断 方案的准确选择,并可通过增加新的诊断知识来完善故障诊断知识库.     

基于两阶段DEA的空中突防兵力方案评价方法

以效费比优选兵力方案是作战方案制定中的关键技术。以飞机编队突防作战为研究背景,用系统动力学的方法构建突防编队依次通过飞机拦截区与地空武器拦截区的兵力损失模型。将突防过程抽象为类型3的两阶段数据包络分析模型,证明其与类型1模型在效率加性分解与乘性分解上特性的不同,指出其无偏见性,并分别从两个阶段的输出与输入导向综合定义新的中立性评价方法。在仿真实验中,分别运用3种评价方法对可选兵力方案的两阶段与整体效率进行评价比较,根据任务要求,选取最优兵力方案。     

多因素分离过程蒙特卡罗仿真平台设计

火箭和导弹等运载工具在飞行过程中涉及多种分离,分离过程出现问题会导致整个任务的失败。分离过程中分离体受到多种干扰因素和误差的影响,而靶场试验次数有限,无法得到多因素对分离过程的综合影响。设计了通用型的分离模型,建立包含多种力和干扰的分离载荷库,基于蒙特卡罗随机打靶技术,能够对多种分离过程进行打靶分析,得到多因素干扰的影响情况。对某导弹头罩分离过程进行了蒙特卡罗打靶仿真,得到了在多种偏差因素下分离体的运动范围。     

民用飞机多地域航材支援网络模型研究

航材支援保障对于民用飞机安全可靠营运至关重要, 民用飞机运营在不同地区, 以客户需求为牵引的航材支援同时受到地域环境和运输方式的影响。为了实现民用飞机航材敏捷支持, 本文综合考虑多因素的影响, 提出了航材支援网络节点权衡的嵌套层次分析法(nested analytic hierarchy process, NAHP), 以及基于遗传算法(genetic algorithm, GA)的民用飞机多地域航材支援网络模型。结合民用飞机多地域运营特点, 对航材支援网络影响因素进行研究, 并运用NAHP对航材支援网络节点进行权衡分析, 对备选节点的重要性进行排序以得到航材支援网络目标节点, 从而构建以时效性为优化目标的多地域航材支援网络节点类型定位与多式联运路径优化模型, 并进行GA适用性设计以对模型求解。最后, 通过与人工规划航材支援方案对比, 对所提方法和模型的有效性进行验证。结果表明,所提方法能够合理确定航材支援网络节点的类型和辐射范围, 同时以最短时间完成航材支援任务, 可为民用飞机在多地域运营的航材支援网络搭建提供可行的方法和思路。     

基于绝对坐标的实体单元在多体系统动力学中的应用

为研究具有复杂几何外形的柔性多体系统的动态应力响应或大变形运动,需提供一种能描述复杂几何外形并支持大变形的柔性体建模方法。利用完全非线性有限元方法,在多体系统框架下,开发包括线性和二次插值两种类型的四面体、五面体和六面体6种三维大变形实体单元,为准确描述多体系统中实体柔性体的大变形和任意的刚体运动提供一种建模方法。同时通过引进虚刚体建立实体单元和刚体的约束,利用赫兹理论处理实体单元和刚体之间的碰撞问题,将实体单元与多体系统有机结合在一起。最后通过数值算例验证了实体单元在多体系统动力学中的应用可行性和有效性。     

地板下结构参数对民机适坠性的影响及优化

为了确保乘员在可生存事故中存活,民机结构必须具备适坠特性.适坠性设计的关键部位为客舱地板以下结构,包括底框、行李舱底部结构和行李舱支柱三个元素.对民机典型机身结构进行了简化,利用LS-DYNA3D建立了1/4缩比动力学仿真模型,考察了行李舱支柱位置、角度及行李舱高度变化对机身坠撞特性的影响.以改善机身适坠性能为目标对地板以下结构参数进行了综合优化,优化过程采用基于均匀试验设计的Kriging近似模型,大大降低了动力学优化的计算代价.优化结果表明合理选择行李舱支柱位置、角度及行李舱高度参数可以有效改善民机机身结构的适坠性能.