An aviation oxygen supply system based on a mechanical ventilation model

At high altitudes, an Aviation Oxygen Supply System(AOSS) protects pilots from low pressure and hypoxia by continuously providing oxygen corresponding to the pilots' dynamic respiratory properties.An AOSS mainly consists of oxygen supercharging machines which are used in a high-altitude flight cabin to supply pressurized oxygen to pilots.Therefore, it is of great significance to study the airflow dynamic characteristics of an AOSS for safe, continuous, and efficient oxygen supply.In this paper, an AOSS is firstly simplified and considered as a mechanical ventilation system.Then, its corresponding mathematical model is constructed.Next, to verify the mathematical model, a prototype AOSS with a lung simulator is proposed for an experimental study.Afterwards, to build a foundation for the optimization of the AOSS, the airflow dynamic characteristics of an aircraft are analyzed, and the effects of key parameters on the respiration system are researched.Through experimental and simulation studies, it can be concluded that the mathematical model is effective.Subsequently, for stability during the respiration process, we consider setting the equivalent throttling areas of the inspiration and expiration pipelines smaller within certain limits; additionally, an excessively high oxygen supply pressure will disturb smooth airflow, and in a low-pressure environment, the pressure can be 84 cm H_2O lower than the standard atmospheric pressure.This research can be referred to in the design of an oxygen supply system and the study on optimization of airflow dynamic characteristics.     

利用OpenGL建立运动目标体素模型的方法

三维体素模型的建立是运动目标序列图像产生的基础和关键步骤，三维体素模型就是利用计算机系统将运动目标的几何特性在计算机显示器上直观地表示出来。介绍了应用SGI公司的OpenGL三维图形库和微软的MFC基类库在VC 5.0的编程环境中建立运动目标三维体素模型的方法和过程，并以较复杂的静态飞机模型为例进行了模拟实现，得到较好的效果。     

UG13环境下小型钛合金叶轮的造型方法

阐述了利用ＵＧ１３平台，对小型钛合金叶轮的造型方法。并且针对加工小型钛合金整体叶轮过程中变形和回弹的问题，提出了在造型阶段就主动控制负余量的软件补偿方法。该造型及软件补偿方法在航空某型任务小型钛合金叶轮制造中得到应用     

Multi-disciplinary design optimization with variable complexity modeling for a stratosphere airship

This paper proposes a hybrid architecture based on Multi-disciplinary Design Optimization(MDO) with the Variable Complexity Modeling(VCM) method, to solve the problem of general design optimization for a stratosphere airship. Firstly, MDO based on the Concurrent SubSpace Optimization(CSSO) strategy is improved for handling the subsystem coupling problem in stratosphere airship design which contains aerodynamics, structure, and energy. Secondly, the VCM method based on the surrogate model is presented for reducing the computational complexity in high-fidelity modeling without loss of accuracy. Moreover, the global-to-local optimization strategy is added to the architecture to enhance the process. Finally, the result gives a prominent stratosphere airship general solution that validates the feasibility and efficiency of the optimization architecture. Besides, a sensitivity analysis is conducted to outline the critical impact upon stratosphere airship design.     

Aspects of Global Magnetospheric Processes

Magnetospheric global modeling is a method to link observations from distant regions via physical laws and has long played a unique and crucial role in space physics. It, different from computer simulations, represents the highest level of abstraction of the physical understanding of the processes that cause observed phenomena. It results in various specific models. While it appears in the form of cartoons, it is based on and has to be qualitatively consistent with physical laws. With the advancement of computer simulations, clues to the connection between physical laws and observation can be perceived much more easily than as ever before. However, computer simulation results are highly dependent on the used boundary conditions and numerical methods which may or may not represent the reality, even if the initial conditions are properly set. Therefore, simulations can easily mislead the investigations. Furthermore, a simulation result needs to be examined using diagnostic tools, such as field line tracing and streamline tracing programs. There are uncertainties in these diagnostic methods. The errors can be very large in certain areas under certain conditions. For example, a small error may link two different field lines or stream lines. The interpretations of the simulation results can be misled by these errors. The knowledge of global modeling can be useful in identifying the inconsistencies in the simulations and the flaws in the theoretical interpretation from the simulations. This review-tutorial article outlines the principles of the global modeling and discusses the successes and flaws of several global models.     

Regional 4-D modeling of the ionospheric electron density from satellite data and IRI

Accurate knowledge of the electron density is the key point in correcting ionospheric delays of electromagnetic measurements and in studying ionosphere physics. During the last decade Global Navigation Satellite Systems (GNSS) have become a promising tool for monitoring ionospheric parameters such as the total electron content (TEC). In this contribution we present a four-dimensional (4-D) model of the electron density consisting of a given reference part, i.e., the International Reference Ionosphere (IRI), and an unknown correction term expanded in terms of multi-dimensional base functions. The corresponding series coefficients are calculable from the satellite measurements by applying parameter estimation procedures. Since satellite data are usually sampled between GPS satellites and ground stations, finer structures of the electron density are modelable just in regions with a sufficient number of ground stations. The proposed method is applied to simulated geometry-free GPS phase measurements. The procedure can be used, for example, to study the equatorial anomaly.     

Using PoF models to predict system reliability considering failure collaboration

Existing Physics-of-Failure-based (PoF-based) system reliability prediction methods are grounded on the independence assumption, which overlooks the dependency among the compo-nents. In this paper, a new type of dependency, referred to as failure collaboration, is introduced and considered in reliability predictions. A PoF-based model is developed to describe the failure behavior of systems subject to failure collaboration. Based on the developed model, the Bisection-based Reliability Analysis Method (BRAM) is exploited to calculate the system reliabil-ity. The developed methods are applied to predicting the reliability of a Hydraulic Servo Actuator (HSA). The results demonstrate that the developed methods outperform the traditional PoF-based reliability prediction methods when applied to systems subject to failure collaboration.     

敏捷性导弹的双网络逆动态模糊神经网络控制

新疆敏捷性导弹为了获得更高的机动性、敏捷性和好的导引精度，许多采用推力矢量控制方案，本文讨论了一类带推力矢量控制导弹的数学建模，在此基础上提出了一种适用于此类新型导弹的模糊神经网络控制方案，采用双网络逆动态学控制结构，数字仿真表明所提出的控制方案对于系统内参数不确定性和非线性变化具有强的适应性。     

一种共轴式直升机操纵机构的运动学建模与分析

 共轴式直升机操纵机构的输入/输出运动学关系复杂、非线性严重,不同通道间控制耦合大,其中航向采用全差动的操纵机构最为复杂。为了分析用比例关系简化建模所引起的误差及利用逆运动学进行操纵系统线性化,必须对操纵机构运动学进行精确建模。针对一种航向全差动操纵机构,首先,运用机构学原理,通过去除过约束、局部自由度对机构进行简化,计算得到操纵机构自由度;然后,将操纵机构分为3个子模块,通过对每个模块应用空间机构位置分析方法进行正向、逆向运动学推导,建立系统完整的运动学模型;利用光学测量原理设计了测试系统,并通过实验验证了所建模型的正确性;最后给出了所建模型在共轴式直升机建模、操纵解耦及线性化方面的应用方法。     

漂浮基空间机器人捕获卫星过程动力学模拟及捕获后混合体运动的RBF神经网络控制

 讨论了漂浮基空间机器人在轨捕获目标卫星过程的碰撞动力学建模,以及捕获操作结束后空间机器人与卫星混合体的稳定控制问题。首先采用多刚体动力学建模方法并结合空间机器人捕获目标卫星过程中的碰撞动力学特性,建立了漂浮基空间机器人在轨捕获漂浮卫星过程的动力学模型,并在此基础上计算出完成捕获操作后空间机器人与目标卫星混合体关节的运动速度。然后针对卫星及空间机器人系统惯性参数均是未知的复杂情况,应用上述模型、神经网络控制理论和Lyapunov稳定性理论,设计了空间机器人与卫星混合体在捕获过程碰撞冲击影响下稳定运动的高斯径向基函数神经网络控制方案,以达到对捕获卫星的有效控制。此外,高斯径向基函数神经网络控制方案具有不需要测量和反馈载体位置、移动速度与加速度的显著优点。系统数值仿真证实了上述控制方案的有效性。