Ionospheric losses of Venus in the solar wind

The nature of ionospheric losses from Venus is of essential importance for understanding the ionosphere dynamics of this unmagnetized planet. A plausible mechanism that can explain the escape of charged particles involves the solar wind interaction with the upper atmospheric layers of Venus. The hydrodynamic approach proposed for plasma expansion in the present study comprises two populations of positive ions and the neutralizing electrons, which interact with the solar wind electrons and protons. The fluid equations describing the plasma are solved numerically using a self-similar approach. The behavior of plasma density, velocity, and electric potential, as well as their reliance upon solar wind parameters have been examined. It is found that for noon midnight sites, the oxygen ion-to-electron relative density may be the main factor to enhance the ionic loss. However, the other parameters, like hydrogen density and solar wind density and velocity seem to do not stimulate the runaway ions. For lower dawn-dusk region, the plasma are composed of hydrogen and oxygen ions as well as electrons, but for higher altitudes only hydrogen ions and electrons are encountered. All ionic densities play an important role either to reduce or boost the ionic loss. The streaming solar wind velocity has no effect on the plasma escaping for lower altitudes, but it reduces the expansion at higher altitudes.     

飞行试验资源规划与应用模式研究

以飞行试验过程中的飞行组织管理实践为基础,通过对人力资源、空域资源、物力资源及其他影响飞行试验的约束性资源的分析,采用解释结构模型对其进行建模研究,得出系统框图,直观地反映出影响飞行试验的各种因素间的优先级顺序和逻辑结构,同时形成了飞行试验资源结构模型的应用模式,具有一定的实用价值。     

加强学科综合教学培养实际应用技能--《机械制图》中零件表面粗糙度综合教学法探讨

以机械制图课程中零件表面粗糙度为例，进行了学科综合教学法探讨，提出了新时期高等职业技术教育培养学生的新观点，学习贵以致用，应用综合知识，解决实际问题，提高高职技术人才应用技能。     

从计算机系统角度分析软件可靠性

从硬／软件综合的角度对计算机进行可靠性研究具有非常重要的意义。本文作者对硬、软件相互作用进行了明确的划分和定义。并指出，是现行的软件可靠性黑箱分析方法禁锢了人们从更深层次对于硬／软件系统可靠性进行研究。基于上述认识，本文提出了解决软件分解单元之间耦合问题的办法。进而提出了一种新的软件可靠性分析方法，为对计算机系统进行可靠性分析时，考虑硬、软件之间的复杂的相关作用提供了基础，从而为更准确地评估计算机系统的可靠性提供了可能。文中分析了一个飞行控制系统实例。     

轻型空间CCD相机模态分析及结构建模方法研究

文章以大型结构设计软件Pro/E、前后处理软件PATRAN及分析软件NASTRAN为基础 ,研究了轻型空间CCD相机的结构建模方法 ,建立了相机的超大规模有限元模型 ,并对该相机主要零部件及整机等多种状态进行模态分析 ,在验证该相机结构设计的合理性的同时有效地改进了设计。     

一种基于模糊机理模型的混事建模方法

本文提出了一种基于模糊机理模型的混合建模方法。采用模糊逻辑系统建立机理模型，RBF神经网络建立系统的补偿模型。这种方法具有建模精度高、物理意义明确以及适应范围大的特点。仿真结果进一步证实了这种方法的有效性。     

Near real-time modeling of global ionospheric vertical total electron content using hourly IGS data

The International GNSS Service (IGS) has been providing reliable Global Ionospheric Maps (GIMs) since 1998. The Ionosphere Associate Analysis Centers (IAACs) model the global ionospheric Total Electron Content (TEC) and generate the daily GIM products within the context of the IGS. However, the rapid and final daily GIM products have a latency of at least one day and one week or so, respectively. This limits the value of GIM products in real-time GNSS applications. We propose and develop an approach for near real-time modeling of global ionospheric TEC by using the hourly IGS data. We perform an experiment in a real operating environment to generate near real-time GIM (named BUHG) products for more than two years. Final daily GIM products, Precise Point Positioning (PPP) based VTEC resources, and JASON-3 Vertical TEC (VTEC) measurements are collected for testing the performance of BUHG. The results show that the performance of BUHG is very close to that of the daily GIM products. Also, there is good agreement between BUHG and PPP-derived VTEC as well as with JASON-3 VTEC. It is possible that BUHG would be further improved with an increase in available hourly GNSS data.     

BTT导弹三维制导控制一体化建模与仿真

针对带有一定机动能力的飞行目标,结合弹目运动关系与导弹自身的动力学特性,给出了倾斜转弯(BTT)拦截导弹的俯仰、滚转、航向三通道独立制导控制一体化(IGC)设计。首先分别建立三通道数学模型,并给出了指令信号的计算形式,随后设计了基于动态面的IGC反步控制算法,最后在三维空间下进行目标拦截仿真验证。仿真结果表明,所建立的三通道模型能够充分描述目标与导弹之间的运动关系,设计的算法能够实现导弹对目标的精确拦截,且具有一定的抗机动能力。