k-ε-g紊流燃烧模型数值研究

本文对k-ε-g紊流燃烧模型中模型系数C_R,C_(g1),C_(g2)的选定和计算浓度脉动均方值g的不同方法进行数值研究。计算结果表明模型系数值的选定直接与化学反应速率有关,而其中C_R影响最大。g的计算虽然可有不同方法,而其中微分方程求解最佳。并用实验数据来验证计算结果。     

1/spl phi/ 3W grid-connection PV power inverter with partial active power filter

This paper presents a single-phase three-wire (1/spl phi/ 3W) grid-connection photovoltaic (PV) power inverter with a of partial active power filter (PAPF) feature, which can not only deal with PV power but filter current harmonics and improve power factor. Once the processed power exceeds the switch ratings, the inverter can reduce its output reactive power and harmonic power, while still supplying the maximum real power generated by the PV arrays. In the derivation of control laws, a limit circle is defined to confine the output power of the inverter. To determine the power that the inverter can process, the instantaneous reactive power of a 1/spl phi/ 3W system is defined and used to calculate reactive power, which can avoid complex detections of phase angle and magnitude of the fundamental component of a nonlinear load current. Simulation results and experimental measurements have verified the proposed algorithm and the feasibility of the inverter.     

掠海飞行导弹击水概率的仿真研究

本文对掠海导弹的击水概率问题进行了研究,提出了用均匀设计、Monte—Carlo法和逐步回归法建立击水概率预报公式的仿真方法,并结合某型号的反舰导弹进行计算,得到了满意的结果。本文还利用表观频率和表观频谱的概念,建立起飞航导弹的背景干扰——海浪和阵风的数学模型,并用波叠加法进行了数字仿真。     

星光折射航天器自主定轨方案比较

当星光透射大气发生折射时 ,用星光折射角精确地反映星光在大气中离地球表面的高度 ,并建立高度、航天器与地球的几何关系。通过对折射角进行观测 ,间接测得地平 ,从而改善了用地平仪直接测地平所造成的航天器自主导航精度低的不足。本文提出了几种利用星光折射的航天器自主定轨方案 ,并作了细致的仿真实验 ,对直接和间接两种测量地平方法以及几种星光折射自主定轨方案进行了分析比较。     

Ariane transfer vehicle in service of man in orbit

The Ariane transfer vehicle (ATV), an Ariane 5 borne, unmanned propulsion vehicle, is designed to transport the logistics needed to resupply the International Space Station (ISS) and the man tended free flyer (MTFF) step 2 with pressurized and unpressurized cargo and to dispose the waste. The ATV is an expendable vehicle and is disposed of by a safe atmospheric burn up. In accordance with the AR5 schedule it should be operational in 1996 for missions toward ISS and beyond the year 2000 for MTFF 2 missions. The main constituents of the proposed ATV are the modified AR5 third stage L5, an upgraded VEB steering the launcher as well as the ATV and the P/L-adaptor providing mechanical and umbilical links to the payload. The mechanical part of the RVD-kit will be placed on the payload-module, the main RVD sensors are located on the adaptor and the needed computer intelligence will be integrated on the VEB. To minimize the development, and recurring costs, the ATV concept fully complies to the idea of maximum use of existing hardware and software, mainly from the AR5, Hermes and Columbus programs thus minimizing development and recurring costs. The ATV is compatible to ISS, MTFF and OMV and is able to transport logistic modules compatible with NSTS and U.S.-expendable launchers.     

开放式飞行任务规划方法

本文给出了一种基于分布式黑板结构的开放式飞行任务规划方法，简要叙述了飞行器飞行任务规划的概念和其独特要求，并对飞行任务规划的数据预处理、知识表达、规划方法作了深入的探讨。最后介绍了分布式黑板的结构和运行方式。     

航天飞行器防热部件烧蚀行为的数值模拟

对航天飞行器防热部件在氧－煤油发动机火焰喷吹下的烧蚀行为进行了有限元数值模拟。利用“杀死”单元的方法建立防热部件瞬态温度场的有限元模型，实现了烧蚀边界的退缩，从而完成了对烧蚀尺寸变化的定量描述。烧蚀开始于4．59s，到12s时线烧蚀量为1．47mm。计算结果与试验的实测结果一致。     

LISA — a study of the ESA cornerstone mission for observing gravitational waves

The primary objective of the Laser Interferometer Space Antenna (LISA) mission is to detect and observe gravitational waves from massive black holes and galactic binaries in the frequency range 10⁻⁴ to 10⁻¹ Hz. This low-frequency range is inaccessible to ground-based interferometers because of the unshieldable background of local gravitational noise and because ground-based interferometers are limited in length to a few km. LISA is an ESA cornerstone mission and recently had a system study (Ref. 1) carried out by a consortium led by Astrium, which confirmed the basic configuration for the payload with only minor changes, and provided detailed concepts for the spacecraft and mission design. The study confirmed the need for a drag-free technology demonstration mission to develop the inertial sensors for LISA, before embarking on the build of the flight sensors. With a technology demonstration flight in 2005, it would be possible to carry out LISA as a joint ESA-NASA mission with a launch by 2010 subject to the funding programmatics. The baseline for LISA is three disc-like spacecraft each of which consist of a science module which carries the laser interferometer payload (two in each science module) and a propulsion module containing an ion drive and the hydrazine thrusters of the AOCS. The propulsion module is used for the transfer from earth escape trajectory provided by the Delta II launch to the operational orbit. Once there the propulsion module is jettisoned to reduce disturbances on the payload. Detailed analysis of thermal and gravitational disturbances, a model of the drag-free control and of the interferometer operation confirm that the strain sensitivity of the interferometer will be achieved.     

按降低轨迹灵敏度综合最优设计飞行控制系统

本文提出了一个按降低轨迹灵敏度综合最优设计飞行控制系统的方法。它能使系统具有满意的动态品质,同时对系统参数的变化及非线性产生的影响具有较强的鲁棒性。该设计方法具有通用性和程序化,系统实现简单。     

态势评估领域知识的表示方法研究

从分析态势评估专家系统的结构出发,研究战场态势评估知识库的构建,进而对态势评估的领域知识进行归纳,并通过示例探讨对态势评估领域知识的表示方法,同时把可信度方法引入态势评估不确定性知识的表示,给出了复合条件可信度的计算方法。