Q—GERT在开发研究管理中的应用

本文在GERT(Graphcial Evaluation and Review Tehniquec)解析性解法与仿真解法的基础上,给出了我国开发研究管理中应用Q—GERT建模的方法,对于某预研任务建立了网络模型,进行了相应的分析与计算,取得了管理中所需要的一系列重要信息,提出了应用模型进一步进行分析、预测与管理的意见。基于对仿真结果的分析,本文提出了“关键事项”的概念,针对所建模型给出一种评审方法。本文还对概率值的灵敏性规律进行了探讨。在上述工作过程中,开发了一个有用的Q—GERT软件,为在科研管理中采用Q—GERT法创造了条件。     

基于离散事件方法的AFDX建模与仿真

采用了建模仿真的方法来分析航空电子全双工交换式以太网(AFDX,Avionics Full Duplex switched ethernet)协议.通过对AFDX协议的抽象,基于离散事件的建模方法,以基本的网络元素来抽象化网络中的端系统、交换机等设备,以离散事件来描述网络设备的行为,以此构建了AFDX网络模型,并依据模型实现了仿真.网络演算是一种理论计算AFDX最坏延迟界限的方法,将典型场景下仿真得到的结果与理论计算的结果进行比较,验证了模型.通过不同流量方案下仿真结果的对比,对AFDX进行了传输特性的分析.      

航空电子环境下FC网络的建模与仿真

机载网络是航空电子系统的重要部分.从航电系统对数据传输的需求出发,研究了光纤通道(FC,Fibre Channel)网络复杂混合拓扑的建模与仿真.在协议分析的基础上,将不同拓扑结构的网络抽象成终端与交换机模型的组合,并分别建模.基于离散事件系统仿真方法构建了适合航空电子环境的FC网络仿真平台,并提供网络吞吐量、延迟和实时性等性能指标的评价方法.仿真结果与实测数据相对比,误差小于10％,验证了模型的有效性.使用仿真模型进行案例分析,对机载FC网络做出性能评价.      

区域运输规划模型系统

提出一种区域运输规划模型系统,以求从定量的角度,预测一个区域内的货物运输量,继而确定这些运输量对该区域内存在的多种运输方式的偏好结构,最后仿真这些运量在相应的各种运输网络上的分布情况,同时仿真模型还对运输网线路经过新建或扩建后所形成的新的运量分布进行模拟。根据运量分布情况,就可提出初步的规划建设方案。     

复杂深空通信网络的LTP传递时延建模及验证

针对简化场景下建立的LTP（Licklider Transmission Protocol）传递时延模型无法直接应用于复杂场景的问题，提出了一种复杂深空通信网络的LTP传递时延理论模型。已有研究多关注于一到两跳的简化场景或 bundle 保管开启状态下多跳场景数据传输模型的建立，然而其结果在复杂深空通信网络中，对于在 bundle 保管关闭状态下的深空通信并不适用。本文对LTP在复杂深空通信网络中的传输机制进行了分析，基于此分析对LTP在复杂深空通信网络中的传递时延进行了理论建模，搭建了仿真验证平台，仿真分析了模型的正确性及优势。结果表明，该模型计算结果与实验结果较为吻合，相比基于简化场景建立的理论模型，本文所提出的模型更加适用于复杂深空通信网络。      

基于贝叶斯网络的关键链项目管理模型

针对项目进度管理问题,在分析关键链项目管理方法和贝叶斯网络模型技术的基础上,建立了关键链项目管理贝叶斯网络模型（CCPMBN）。首先给出了CCPMBN的基本定义,详述了模型中的节点、有向边及节点条件概率分布信息。然后,提出了面向贝叶斯网络的关键链工序分解方法,研究了基于项目关键链信息的CCPMBN建模方法。针对关键链模型中的大量资源冲突情况,分析了CCPMBN中的各类冲突结构,并给出了冲突描述及化解方法。最后,通过CCPMBN基本性质和特征分析表明了贝叶斯网络模型在项目进度管理中的应用前景。     

基于OPNET的CAN网络建模与仿真

为分析控制器局域网(Controller Area Network, CAN)协议,评价CAN网络性能,提出在OPNET网络仿真环境中CAN网络模型的建模方法.采用网络层次化建模方法构建节点模型.介质访问控制(Medium Access Control, MAC)子层中设计MAC、错误处理和帧间空间模块,保证系统结构清晰.通过进程设计,MAC模块中实现了网络实时性模型;错误处理模块中实现了连续错误下网络不可用模型.定义和编辑链路及数据帧模型.根据实例模型进行网络模型的配置和仿真.仿真结果与实例测试结果一致,验证了网络模型的有效性.通过分析具体网络仿真环境下的仿真结果,对CAN网络性能进行了讨论.该模型提供了独立可编辑的节点模型,链路模型和数据帧模型,可实现灵活的网络配置,用于不同网络拓扑分析.     

基于CIDBN的战术活动识别模型及在线精确推理

战术活动识别是战场态势感知的重要研究内容。为提高战术活动识别的准确性与实时性,提出了一种基于上下文独立动态贝叶斯网络（CIDBN）的战术活动识别模型及在线精确推理。通过对战术活动机制的分析,采用动态贝叶斯网络（DBN）理论,建立了一个初始战术活动识别模型。该模型引入了威胁指数节点来影响战术活动的终止与选择,并采用模糊隶属度函数对连续变量进行离散化处理。依据上下文独立关系对该模型进行简化,获得了一个基于CIDBN的战术活动识别模型。将接口算法扩展于该模型上,提出了在线精确推理算法。仿真结果表明,所提出的战术活动识别方法,具有识别精度高、较低不确定性和实时性高的优点。      

随机网络仿真分析法在交通运输中的应用

本文就多个城市间建立交通运输线的课题应用随机网络技术(VERT-3)构建了一个较大的仿真模型。该模型具备强有力的逻辑判断功能和路线选择功能,并具备一定的通用性。课题仿真已通过计算机运算。结论表明,VERT-3技术具有处理较大型课题的能力。     

Learning in an immersive digital theater

The Houston Museum of Natural Science, in collaboration with Rice University has an outreach program taking portable digital theaters to schools and community sites for over five years and has conducted research on student learning in this immersive environment. By using an external independent evaluator, the effectiveness of NASA-funded Education and Public Outreach (EPO) projects can be assessed. This paper documents interactive techniques and learning strategies in full-dome digital theaters. The presentation is divided into Evaluation Strategies and Results and Interactivity Strategies and Results. All learners from grades 3–12 showed statistically significant short-term increase in knowledge of basic Earth science concepts after a single 22-min show. Improvements were more significant on items that were taught using more than one modality of instruction: hearing, seeing, discussion, and immersion. Thus immersive theater can be an effective as well as engaging teaching method for Earth and Space science concepts, particularly those that are intrinsically three-dimensional and thus most effectively taught in an immersive environment. The portable system allows taking the educational experience to rural and tribal sites where the underserved students could not afford the time or expense to travel to museums.     

Scaling analysis and model estimation of solar corona index

A monthly average solar green coronal index time series for the period from January 1939 to December 2008 collected from NOAA (The National Oceanic and Atmospheric Administration) has been analysed in this paper in perspective of scaling analysis and modelling. Smoothed and de-noising have been done using suitable mother wavelet as a pre-requisite. The Finite Variance Scaling Method (FVSM), Higuchi method, rescaled range (R/S) and a generalized method have been applied to calculate the scaling exponents and fractal dimensions of the time series. Autocorrelation function (ACF) is used to find autoregressive (AR) process and Partial autocorrelation function (PACF) has been used to get the order of AR model. Finally a best fit model has been proposed using Yule-Walker Method with supporting results of goodness of fit and wavelet spectrum. The results reveal an anti-persistent, Short Range Dependent (SRD), self-similar property with signatures of non-causality, non-stationarity and nonlinearity in the data series. The model shows the best fit to the data under observation.     

Stochastic particle acceleration by the forced interaction of relativistic current sheets

We address the problem of interacting relativistic current sheets in self-consistent kinetic plasma simulations within the framework of the Particle-In-Cell model. The interaction is enforced in head-on collisions of up to 10 current sheets at relativistic bulk speeds. The simulations are motivated by the general problem of Poynting flux dissipation in ‘striped wind’ configurations presumably governing the relativistic outflows pervasive in pulsar winds and gamma-ray bursts. We identify the generation of non-thermal particles and formation of a stable power-law shape in the particle energy distributions f(γ) dγ ∝ γ^−s dγ. In 1D, a spectral index s ∼ 2 is observed and attributed to a stochastic Fermi-type acceleration mechanism. In 2D, the generic index of s ∼ 3–4 is retained as in previous simulations of individual current sheets. Whereas in 2D the high energy cut-off is constrained by the limited dissipation of magnetic energy, in 1D the process converts the bulk motion of current sheets towards directed particle momentum of an exclusive class of non-thermal particles.     

Development of a gas chromatography compatible Sample Processing System (SPS) for the in-situ analysis of refractory organic matter in martian soil: preliminary results

In the frame of the 2009 Mars Science Laboratory (MSL) mission a new sample preparation system (SPS) compatible with gas chromatography–mass spectrometry (GC–MS) has been developed for the in situ analysis of complex organic molecules in the Martian soil. The goal is to detect, if they exist, some of the key compounds that play an important role in life on Earth including carboxylic acids, amino acids and nucleobases.     

基于LuGre模型的电液加载系统摩擦补偿

为了提高电液加载系统控制精度,针对摩擦问题提出了基于LuGre摩擦模型的前馈补偿方法.建立了用于摩擦仿真分析和补偿器设计的电液加载系统数学模型;通过实验获取并分析了相关的摩擦数据;基于实验数据进行LuGre模型参数辨识,把LuGre模型和辨识结果引入电液加载系统数学模型,并进行仿真结果与实际摩擦数据的对照,证明了LuGre摩擦模型的准确性.设计前馈补偿器,进行了实验对比,实验结果表明前馈补偿器可将摩擦产生的控制误差有效地降至未补偿时的30%左右.      

CoRoT and Kepler results: Solar-like oscillators

The space-borne observatories CoRoT (Convection Rotation and planetary Transits) and Kepler have provided photometric time series data of unprecedented precision for large numbers of stars. These data have revolutionized the fields of transiting exoplanets and asteroseismology. In this review some important asteroseismic results obtained using data from the CoRoT and Kepler space missions concerning stars that show solar-like oscillations are discussed. These results comprise, among others, measurements of the location of the base of the convection zone and helium second-ionization zone in main-sequence stars, the presence (or not) of core-helium burning in red-giant stars, as well as differential rotation in these stars.     

Return to Europa: Overview of the Jupiter Europa orbiter mission

Missions to explore Europa have been imagined ever since the Voyager mission first suggested that Europa was geologically very young. Subsequently, the Galileo spacecraft supplied fascinating new insights into this satellite of Jupiter. Now, an international team is proposing a return to the Jupiter system and Europa with the Europa Jupiter System Mission (EJSM). Currently, NASA and ESA are designing two orbiters that would explore the Jovian system and then each would settle into orbit around one of Jupiter’s icy satellites, Europa and Ganymede. In addition, the Japanese Aerospace eXploration Agency (JAXA) is considering a Jupiter magnetospheric orbiter and the Russian Space Agency is investigating a Europa lander.     

Radioactivity of the Moon and planets

In this report the main results of the study of radioactivity of the solar sistem bodies are considered. The radioactivity of the Moon and planets was measured by means of vehicles in situ. The radioactivity of the lunar samples, brought to the Earth was studied with laboratory equipment.     

基于最小值原理的冗余度机器人动力学控制

为了解冗余度机器人全局法优化中数值求解的困难,本文讨论了动力学方程的建立,无约束和有约束最优控制问题之间的内在联系,重点分析了求解最优控制问题的数值方法,文中提出了双向异步积分迭代的求解正则方程组的直接迭代法,较好解决了状态方程和协态方程稳定相逆给求解两点这值问题带来的困难。     

基于GPS载波相位的微卫星姿态算法研究

GPS姿态系统是利用GPS载波相位测量来确定载体的航向和姿态角。本文对微卫星的GPS姿态系统进行了研究。重点解决短基线的GPS状态算法，讨论了姿态价格函数的了小化方法。测试结果表明，所提的算法对小于1m的基线是有效的。