平流层飞艇的结构健康监测系统初探

文章从介绍平流层飞艇的结构健康监测定义入手，说明了该系统研究的作用和意义以及工作原理。在分析平流层飞艇运行环境和结构可能的损伤模式的基础上，从工程应用角度出发，对结构健康监测系统方案展开了研究，探讨了平流层飞艇结构健康监测系统中的一些关键因素，为今后结构健康监测系统设计提供参考。     

可控翼伞、返回舱组合体滑翔性能研究

文中采用“九自由度”动力学模型分析了可控翼伞、返回舱组合体的滑翔性能。     

工程知识管理系统模型研究

针对工程知识管理系统模型多样化的现状,从需求、功能和应用三个方面论述了对工程知识管理系统模型的理解和认识以及需求、功能及应用模型的含义和组成。提出工程知识管理系统模型由知识需求、系统功能和知识应用构成。在工程知识管理系统模型的基础上,成功设计开发出工程知识管理系统实例,并在航天企业中形成了一定规模的应用。     

Linear Shaped Charge Cutting Property and Charge Cutting Mechanism of Mg-Gd-Y-Zn Alloy

The linear shaped charge cutting technology is an effective technology for aircraft separation. It can separate invalid components from aircrafts timely to achieve light-weight. Magnesium alloy is the lightest metal material, and can be used to cast effective light-weight components of an aircraft construction. However, the application study of the linear shaped charge cutting technology on magnesium alloy components is basically blank. In response to the demand for the linear separation of magnesium alloys, the Mg-12Gd-0.5Y-0.4Zn alloy is selected to carry out the target shaped charge cutting test. The effects of the shaped charge line density, cutting thickness, and mechanical properties on the cutting performance of the alloy are studied. The shaped charge cutting mechanism is analyzed through the notch structure. The results show that the linear shaped charge cutting performance is significantly affected by the penetration and the collapse. The higher the linear density is, the stronger the ability of the linear shaped charge cutter is, and the greater the penetration depth is, which is advantageous. However, the target structure will be damaged when it is too large (e.g., 4.5 g?m-1). Within 12 mm, when the cutting thickness of the target increases, the penetration depth increases. The lower the tensile strength is, the greater the penetration depth is, and the more conducive the penetration depth to the shaped charge cutting is. When the elongation (EL) increases to 12%, the collapse of the target is incomplete and the target cannot be separated. When the tensile strength of the Mg-Gd-Y-Zn alloy is less than 350 MPa, the EL is less than 6.5%, the cutting thickness is less than 12 mm, and the linear shaped charge cutting of the magnesium alloy can be achieved stably.     

A DISSIPATION-DISPERSION TURBULENCE THEORY AND ITS MODIFIED k-ε MODEL

Based on the perturbation equation of the Navier-Stokes equation and the instability analysis of strongly nonlinear flow. a set of new control equations is presented featuring the interaction between dissipation and dispersion of turbulence. Three extra terms repr(?)nting respectiveiy the effects of extra strains, rotation and dispersion on the turbulent stresses introduced into the momentum equation. The defects of the original k-(?) model are removed mainly by introducing new (?) terms. This modified k-(?) model has advantages of simplicity, self-consistency and clarity of physics It is abie to handle complex flows and provides new perspectives for looking at a diversity of turbulence problems, such as inter(?)ttency, coberent structure,anisotropy, turbulent energy inversion and the cut-off of turbulence spectra.     

湍流的耗散及弥散相互作用理论

 湍流具有涡团散裂、耗散和弥散的特性。根据Prigogine倡导的耗散结构理论,推导了表征耗散与弥散相互作用的新的湍流控制方程组。其特点是:用稳定性分析得到湍流动能产生项,再根据广义熵增原理推出并列存在的,分别适用于强弱涡量的二个湍流动量方程。运用该理论已成功地计算了一些典型的湍流问题:湍流边界层中的马蹄涡拟序结构、钝体涡尾区的湍流能量逆转、湍流涡团散裂弛豫及各向异性分布。文中给出了部分算例。     

挖补修理对复合材料层合板拉伸性能的影响

挖补修理是一种先进的复合材料层合板损伤修理技术,分为斜接法和阶梯法两种类型。本文研究不同修补结构对斜接法挖补修理试验件力学性能的影响。对斜接法楔形砂磨斜坡比率为1:10、1:20、1:30和1:40的复合材料层合板修理试验件的拉伸性能进行了研究,同时总结了斜接法修理后试件的断裂位置特征。结果表明:斜接法斜坡比率为1:30的挖补修理试件的抗拉强度最好,外加补片会提高试件的抗拉强度,外加补片层数2层为宜。断裂类型主要有脱胶断裂和补片断裂。     

THEMIS Ground-Based Magnetometers

The THEMIS mission includes a comprehensive ground-based measurement network that adds two additional dimensions to the information gained in the night magnetosphere by the five THEMIS spacecraft. This network provides necessary correlative data on the strength and extent of events, enables their onsets to be accurately timed, and provides an educational component in which students have an active participation in the program. This paper describes the magnetometers installed to obtain these ground-based North American magnetic measurements, including the magnetometers installed as part of the educational effort, and the support electronics provided by UCLA for the ground-based observatories. These magnetometers measure the Earth’s magnetic field with high resolution, and with precise timing provided by the Global Positioning System. They represent UCLA’s next generation of low-cost, ground-based magnetometers using an inexpensive personal computer for data collection, storage and distribution. These systems can be used in a stand-alone mode requiring only AC power. If there is Internet connectivity, they can be configured to provide near real-time data over the web. These data are provided at full resolution to the entire scientific community over the web with minimal delay.     

The THEMIS Magnetic Cleanliness Program

The five identical THEMIS Spacecraft, launched in February 2007, carry two magnetometers on each probe, one DC fluxgate (FGM) and one AC search coil (SCM). Due to the small size of the THEMIS probes, and the short length of the magnetometer booms, magnetic cleanliness was a particularly complex task for this medium sized mission. The requirements leveled on the spacecraft and instrument design required a detailed approach, but one that did not hamper the development of the probes during their short design, production and testing phase. In this paper we describe the magnetic cleanliness program’s requirements, design guidelines, program implementation, mission integration and test philosophy and present test results, and mission on-orbit performance.     

三维空间拦截的前置追踪变结构制导律(英文)

This article aims to develop a head pursuit （HP） guidance law for three-dimensional hypervelocity interception, so that the effect of the perturbation induced by seeker detection can be reduced. On the basis of a novel HP three-dimensional guidance model, a nonlinear variable structure guidance law is presented by using Lyapunov stability theory. The guidance law positions the interceptor ahead of the target on its tlight trajectory, and the speed of the interceptor is required to be lower than that of the target, A numerical example of maneuvering ballistic target interception verifies the rightness of the guidance model and the effectiveness of the proposed method.