Concept Design,Modeling and Station-keeping Attitude Control of an Earth Observation Platform

The stratosphere airship provides a unique and promising platform for earth observation. Researches on the project design and control scheme for earth observation platforms are still rarely documented. Nonlinear dynamics, model uncertainties, and external disturbances contribute to the difficulty in maneuvering the stratosphere airship. A key technical challenge for the earth observation platform is station keeping, or the ability to remain fixed over a geo-location. This paper investigates the conceptual design, modeling and station-keeping attitude control of the near-space earth observation platform. A conceptual design of the earth observation platform is presented. The dynamics model of the platform is derived from the Newton-Euler formulation, and the station-keeping control system of the platform is formulated. The station-keeping attitude control approach for the platform is proposed. The multi-input multi-output nonlinear control system is decoupled into three single-input single-output linear subsystems via feedback linearization, the attitude controller design is carried out on the new linear systems using terminal sliding mode control, and the global stability of the closed-loop system is proven by using the Lyapunov theorem. The performance of the designed control system is simulated by using the variable step Runge-Kutta integrator. Simulation results show that the control system tracks the commanded attitude with an error of zero, which verify the effectiveness and robustness of the designed control system in the presence of parametric uncertainties. The near-space earth observation platform has several advantages over satellites, such as high resolution, fast to deploy, and convenient to retrieve, and the proposed control scheme provides an effective approach for station-keeping attitude control of the earth observation platform.

Design of micropiles to increase earth slopes stability

A methodology was proposed for the design of micropiles to increase earth slopes stability. An analytic model based on bearn-colurnn equation and an existing P-y curve method was set up and used to find the shear capacity of the micropile. Then, a step-by-step design procedure for stabilization of earth slope with rnicropiles was introduced, involving six main steps： 1） Choosing a location for the rnicropiles within the existing slope; 2） Selecting micropile cross section; 3） Estimating length of rnicropile; 4） Evaluating shear capacity of mieropiles; 5） Calculating spacing required to provide force to stabilize the slope; 6） Designing the concrete cap beam. The application of the method to an embankment landslide in Qinghai Province was described in detail. In the final design, three rows of rnicropiles were adopted as a group and a total of 126 rnicropiles with 0.23 m in diameter were used. The micropile length ranged between 15 and 18 m, with the spacing 1.5 m at in-row direction. The monitoring data indicate that slope movement has been effectively controlled as a result of the slope stabilization measure, which verifies the reasonability of the design method.

Study on the FEM design of reinforced earth retaining wall with geogrid

At present,limit equilibrium method is often adopted in the design of reinforced earth retaining wall. Geotechnical engineers home and abroad have done a lot of work to improve the traditional calculation methods in recent years,while there are lots of defects. This paper first identifies the location of failure surface and safety factor through the finite element program of PLAXIS and then analyses the influencing factors of the stability of reinforced earth retaining wall with geogrid. The authors adopt strength reduction FEM (finite element method)in the design and stability analysis of reinforced earth retaining wall and have achieved some satisfying results. Without any assumptions,the new design method can automatically judge the failure mode of reinforced earth retaining wall,consider the influence of axial tensile stiffness of the reinforcement stripe on the stability of retaining wall,identify reasonable distance and length of the reinforcement stripe,and choose suitable parameters of reinforcement stripe,including strength,stiffness and pseudo-friction coefficient which makes the design optimal. It is proved through the calculation examples that this method is more reasonable,reliable and economical in the design of reinforced earth retaining wall.

Molecular Design and Electronic Structure of Polynuclear Rare Earth Complexes and Clusters

Studies on the electronic structure,molecular design,syntheses of some novel series of tetranuclear rare earth complexes in our laboratory have been reviewed.Spin-unrestricted localized INDO method was used to calculate the electronic structure and the chemical bonding in the typical rare earth cluster Sc[Sc_6Cl_(12)Co]was discussed.

Optimal design of near-Earth asteroid sample-return trajectories in the Sun–Earth–Moon system

In the 6th edition of the Chinese Space Trajectory Design Competition held in 2014, a near-Earth asteroid sample-return trajectory design problem was released, in which the motion of the spacecraft is modeled in multi-body dynamics, considering the gravitational forces of the Sun, Earth, and Moon. It is proposed that an electric-propulsion spacecraft initially parking in a circular 200-kin-altitude low Earth orbit is expected to rendezvous with an asteroid and carry as much sample as possible back to the Earth in a 10-year time frame. The team from the Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences has reported a solution with an asteroid sample mass of 328 tons, which is ranked first in the competition. In this article, we will present our design and optimization methods, primarily including overall analysis, target selection, escape from and capture by the Earth-Moon system, and optimization of impulsive and low-thrust trajectories that are modeled in multi-body dynamics. The orbital resonance concept and lunar gravity assists are considered key techniques employed for trajectory design. The reported solution, preliminarily revealing the feasibility of returning a hundreds-of-tons asteroid or asteroid sample, envisions future space missions relating to near-Earth asteroid exploration.

Landscape Features and Design Elements of Earth-sheltered Buildings

Categories of earth-sheltered buildings were summarized, and it was proposed that landscape features of earth-sheltered buildings were demonstrated mainly as "ecological, landscape-like and systematic". Landscape elements such as entrance, road, water and greening were believed as major means of showing landscape features of earth-sheltered buildings. Entrance landscape design of such buildings was analyzed from the perspectives of plane-type, slope-type and step-type forms. Road design for these buildings should respect natural terrains so as to connect spaces and organize traffic routes reasonably. Waterscape design should take both landscape effects and loading capacity of roof into consideration so as to meet water-loving psychology of the public, virtual and real approaches should be combined to create waterscapes. Greening design of earth-sheltered buildings was explored from the perspectives of roof greening and vertical greening to improve the green coverage rate and show favorable ecological effects.

Application of Digital Technology in Road and Bridge Design

With the development and progress of science and technology,road and bridge design has experienced rapid development,from the initial manual drawing design to the popularity of Computer-Aided Design(CAD),and then to today’s digital software design era.Early designers relied on hand-drawn paper design forms which was time-consuming and error-prone.Digital support for road and bridge design not only saves the design time but the design quality has also achieved a qualitative leap.This paper engages in the application of digital technology in road and bridge design,to provide technical reference for China’s road and bridge engineering design units,to promote the popularity of Civil3D and other advanced design software in the field of engineering design and development,ultimately contributing to the sustainable development of China’s road and bridge engineering.

Google Earth在土地开发项目规划设计中的应用

Google Earth虚拟地球软件,因其能提供高精度的三维地图和匹配真实地表信息的高清画面而被广泛地应用于各个领域,已在城市轨道交通工程控制网布设、地震应急、水利水电测绘和道路设计等方面得到应用。结合贵州省松桃县后寨村土地开发项目,阐述了Google Earth在项目区选址、现状图绘制、工程设计和三维场景仿真中的应用。

Google Earth在地震勘探中的应用可行性探讨

地震勘探属于野外施工,工区的地形地貌对野外施工和施工质量有很大的影响,在地震勘探的踏勘、设计、施工过程中需要借阅大量的地形图来指导野外生产。Google Earth(谷歌地球)是一款全球卫星地图集成软件,被广泛应用到各个行业,其最大特点就是能够提供大量清晰度很高的卫星图片,对于地震勘探来说,有很高的实用价值。通过对Google Earth软件功能的探索,结合地震勘探各个环节,介绍了利用GoogleEarth如何来进行踏勘;如何下载卫星图片、编制程序实现物理点批量展布来辅助施工设计;如何指导野外生产施工等等。通过实例应用,取得了良好的效果,提高了工作效率,节省了大量的资源。

Google Earth在石油勘探中的应用

从网上下载的Google Earth卫星遥感照片更接近实际地形,在石油勘探初期,经常用它对工区进行踏勘和施工设计。文中详细地介绍了利用Google Earth进行施工设计的方法和步骤。

基于Google earth和BIM的线路设计和外业调查新方法

成塔系列软件是基于Google earth COM API接口和BIM,结合卫星、手机、GPS而开发的地理信息系统软件,旨在扩展Google earth的应用,实现Google earth上直接进行线路设计、高程提取,SRTM DEM下载,CAD等高线绘制,地球影像截图,地形断面生成,AutoCAD、KML(KMZ)、GPS和Excel文件导入导出地球,坐标纠正,地图叠加等功能,提高工作效率。

Google Earth在线路勘测设计中的应用分析

通过分析Google Earth在电力线路勘测及输电线路基建管理中的应用,提出了一种简单可行的构建三维输电线路GIS系统的方法。

基于Google Earth的旅游公司导游跟踪系统的设计

依据旅游管理公司对导游管理的需求以及信息技术的发展,利用Google Earth技术、GPS技术以及相关的通讯技术,构建了旅游公司导游跟踪系统的总体结构方案,描述了该系统所要实现的功能,为实施该系统打下了良好的基础。

Google Earth在输电线路设计中应用

输电线路前期规划阶段常存在资料收集不便、纸质地图时效性差、路径方案比选不够直观性等问题,结合Google Earth在500 kV玉林变～玉林二变线路设计中应用,对Google Earth提供的三维地形数据及卫星影像进行正确性及精度的比较分析,以确定Google Earth资源应用于输电线路设计的可行性、有效性及具体范围,从而使得当前输电线路工程可以低成本方式实现从二维设计向三维设计转变,提高了线路设计效率和准确性,应用前景广泛。

“Google earth+”在道路勘测设计课程教学中的应用

由于Google earth 在道路工程中有着广泛的应用,为改善理论教学与工程实际脱节的问题,在道路勘测设计课程的教学中引入地图应用软件,将实际工程案例引入到平纵横设计、选线、交叉口设计等知识点的教学中,使学生将知识点进一步内化.同时,在课程配套的实习和设计中,亦可使学生熟悉GE 软件在工程中的应用,提高其解决工程实际问题的能力.

基于Google Earth的潘家窑工区煤田三维地震勘探的技术应用

在三维地震勘探项目中,野外采集是一个非常关键的环节,工区的地物状况对野外数据采集和数据采集质量影响很大。在物探项目的踏勘、设计、数据采集过程中需要详细的地图来指导。Google Earth是一款虚拟的三维数字地球软件,在很多领域中被广泛应用。其优点就是能够获取分辨率很高的地面矢量图,能够很好地指导物探项目的生产工作。鉴于Google Earth软件的强大功能以及物探项目工作的特点,描述了基于Google Earth软件技术如何来指导工区地形的踏勘;如何下载高清晰的图片、借助第三方软件来实现地震勘探检波点、炮点批量展布来辅助施工设计;如何指导野外施工等等。通过实例应用,取得了良好的效果,提高了工作效率,节省了大量的资源。

Google Earth在高压送电线路勘测设计中的应用

相比较传统地形图,Google Earth具有图像清晰,信息准确,更新速度快,费用少,有三维效果等优点,更适合应用于高压送电线路勘测设计工作。本文结合1000kV锡盟—南京特高压线路招投标阶段设计工作,对该软件运用于线路设计进行了介绍说明。

浅谈Google Earth在送电线路勘测设计中的应用

简要介绍了GoogleEarth的现况,初步分析了GoogleEarth的平面和高程精度以及在送电线路勘测设计中的应用。

Beam Position and Beam Hopping Design for LEO Satellite Communications

The numbers of beam positions(BPs)and time slots for beam hopping(BH)dominate the latency of LEO satellite communications.Aiming at minimizing the number of BPs subject to a predefined requirement on the radius of BP,a low-complexity user density-based BP design scheme is proposed,where the original problem is decomposed into two subproblems,with the first one to find the sparsest user and the second one to determine the corresponding best BP.In particular,for the second subproblem,a user selection and smallest BP radius algorithm is proposed,where the nearby users are sequentially selected until the constraint of the given BP radius is no longer satisfied.These two subproblems are iteratively solved until all the users are selected.To further reduce the BP radius,a duplicated user removal algorithm is proposed to decrease the number of the users covered by two or more BPs.Aiming at minimizing the number of time slots subject to the no co-channel interference(CCI)constraint and the traffic demand constraint,a low-complexity CCI-free BH design scheme is proposed,where the BPs having difficulty in satisfying the constraints are considered to be illuminated in priory.Simulation results verify the effectiveness of the proposed schemes.

融合Google Earth的船舶监控与应急系统的设计

Google Earth的高分辨率卫星地图资源、三维虚拟环境和人机界面,可以为船舶监控与应急系统提供丰富的地理信息资源。在Google Earth的KML技术及其COMAPI的研究和扩展开发的基础上,对海洋船舶的位置监控、信息融合和救援服务地理信息系统进行分层设计,整体提升船舶信息管理水平。该系统应用在浙江省的渔政应急救援系统项目中,收到良好效果。