Research on storing raster metadata in spatial database

Storage of raster metadata is a key topic in spatial database. Although there are a few of abstract standards on raster metadata, there is not implement standard about it. This paper concludes three storage models implemented in current spatial databases and discusses their advantages and disadvantages. After that analyzing, the paper proposes a mixed storage method which is used the relational table to store structured metadata and used XML to store non-structured metadata, and gives its implementation solution. © 2010 IEEE.

基于GIS的高速公路养护管理信息系统的设计与开发

China is experiencing a rapid development of highway ever since 1990s. By the end of 2004, the total length of the highway summed up to 33 thousand kilometers, ranking 2n in the world. After the open of highway, the accumulation of time and traffic causes the decrease of its capability. To ensure its good quality, security and operation functions, we should take some reasonable measures to maintain it periodically. At present, a big problem is that the traditional maintain measures can no longer meet the increasing requirements. Due to the characters of highway, the relationship of various maintenance data and geographic positions is even closer than any others. If we wan to improve the quality and efficiency of the maintenance work, particularly when there is need for decision-making, a great number of data that is related to geographic positions are absolutely necessary. Evidently, Geographical Information System (GIS) has incomparably advantages in dealing with these spatial information. As a result, a management system for highway maintenance work based on GIS became inevitable for the development of the maintenance of highway. The purpose of this paper is to establish a management system for highway maintenance work base on Geographical Information System (GIS), Global Positioning System (GPS) and spatial database, to manage all kinds of problems encountered in the work, and to provide support on information and methods. My study mainly includes: (1) Analysis on the current status of the maintenance and management work; overview on the history of domestic and international highway maintenance management systems; identifying the necessity and importance for establishing a management system for highway maintenance work based on GIS. (2) Based on the requirement analysis, I proposed a general design for this management system, and discussed the objective, design principles, framework, systematical structure and function design. (3) Outdoor data collection is not only a prime way to understand the current situation of the road, but also an important method for data update after the system is put into use. This paper also intends to establish a set of plan to collect data efficiently and precisely which is based on GIS and GPS technologies. (4) The maintenance management database is a supporting platform for various maintenance decision-makings. Such decisions need the support of a great amount of data, which would cause other problems, such as the diversity of the data source, difference of data formats. This paper also discussed how to deal with these problems and establish such a database. (5) To propose an approach to assess the condition of pavement, based on GIS and related maintenance models. Among all the maintenance models, the two for assessing and forecasting pavement condition are the most important and mature. This paper also analyzed these two models and introduced them in terms of the integration of models. (6) This paper took the Guangshen Highway for example, explaining how to realize a GIS for management of highway maintenance work.

移动复制数据库系统冲突检测及消解策略

复制技术是提高移动数据库系统性能的一项关键技术 .该文提出了一种新的移动复制数据库系统模型——事务级结果集传递 (TL RSP)移动复制模型 ,重点分析了该模型中的冲突检测及消解策略 ,并给出了具体的实现算法 ;TL RSP移动复制模型允许移动用户在系统断连时存取数据库的本地副本并提交事务 ,重新连接时进行冲突的检测及消解 ,同时进行事务结果集的合并 ,最后通过增量刷新的方式进行同步处理 ,使得系统最终收敛于一致性的状态 .此外 ,通过引入简化的事务日志、数据版本号以及权限控制等概念 ,TL RSP模型有效地降低了移动数据库系统的资源消耗 ,保证了数据库的一致性 ,从而为移动数据库系统复制提供了一个可行的解决方案

移动数据库系统乐观事务处理策略

在移动数据库系统中 ,计算平台的移动性、频繁的断接性以及长事务等特性使得传统的事务处理模式不再适用 .为了解决移动数据库中的事务处理问题 ,提出了一种新的移动事务处理模型——乐观两阶段提交移动事务模型 ( O2 PC-MT) .该模型采用乐观并发控制与两阶段提交协议相结合的方法 ,对移动事务的长事务特性提供了灵活与有效的支持 ;此外 ,该模型允许移动计算机分多次发送事务操作 ,且在事务执行的过程中可以任意移动 ,从而提供了对交互式事务及随意移动性的支持 .实验结果表明 ,与基于两段锁协议及其变形的其它移动事务处理模型相比 ,O2 PC-MT提高了系统的事务吞吐率并改善了系统的总体性能

复制的移动数据库系统事务级同步处理策略

同步处理技术是保持复制的移动数据库系统一致性的一项关键技术,但现有的事务级同步处理算法存在着一定的局限性.为了克服这些缺陷,并增强其实用性,提出了一种新的移动数据库同步处理模型──基于双时间印的事务级同步(DTSTLS)模型.DTSTLS模型采用了一种三级复制体系结构,系统可以直接使用通用的数据库产品作为其数据库服务器,因此具有良好的可扩充性.作为一种异步的多主副本复制方法,DTSTLS模型允许移动计算机在断连的情况下存取本地副本,从而造成系统短暂的不一致,重新连接时进行冲突检测及同步处理,使系统重新收敛于一致性的状态.此外,通过一种独特的时间印处理策略,DTSTLS模型减少了通信代价,并降低了资源消耗.实验结果表明,DTSTLS模型提高了移动数据库系统的资源利用效率,保证了事务调度的可串行性和数据库的一致性.

实时数据库缓冲区管理算法的设计和实现

分析了实时数据库的事务特征,对以往的研究成果进行了总结,以满足事务的按时完成比率(SuccessRatio)为目标,为实时系统设计了一种使用反馈控制思想的基于优先级的实时数据库缓冲区管理算法FCLRU2 dl,并将该算法与常用的实时数据库事务调度算法和并发控制策略配合进行了测试和评估,证明了算法的优越性。实验中得到的另一个结论是在特定的事务调度算法和并发控制策略下,实时数据库不需要全部位于内存中,可以不是内存数据库。

浅论实现基于MapX的灌溉信息系统的关键技术

现代化的灌溉用水管理是实现农业高效用水的重要措施之一,它可实现灌溉水资源的合理配置和灌溉系统的优化调度,达到节水增产目的,使有限的水资源获得最大的效益。采用手工方式进行灌溉用水管理,难以及时提供水资源利用最优化方案,因此急需研制出具有网络通信功能的可视化操作界面的灌溉信息管理系统,为灌区水资源评价和利用、规划等工作奠定良好的数据基础。GIS不仅具有强大的空间数据管理功能,还具有丰富的多元地学数据分析处理能力和直观的图形显示效果,因此利用GIS进行灌区的管理与建设将会有效提高灌区的工作效率和经济效益。笔者在实践调研的基础上,根据灌溉信息管理系统的功能规划及结构设计,利用MapX组件工具开发了陕西省冯家山灌区灌溉信息系统,对提高灌溉用水的管理效率进行了实例尝试,并着重对下列关键技术的运用进行了实践与思考:(1)阐述了利用可视化编程工具结合数据库管理技术、地理信息系统组件技术、网络通信技术等进行系统开发的过程;(2)着重介绍了基于MapX组件的空间数据库的建立与关联技术、灌溉管理信息的网络通信实现技术;(3)最后对在灌溉管理工作中运用GIS技术进行科学管理等相关问题进行了有益的探讨。

基于Geodatabase和Arcengine的海岛空间数据库的设计与实现

本文对山东省海岛进行了研究，认识了山东省不同地区海岛的自然环境、资源和开发利用的总体状况。通过对大量的海岛调查资料的整理、分析，提出了利用Geodatabase数据模型构建山东省海岛空间数据库来组织和存储海岛数据的方案，采用GIS软件平台ArcEngine和程序开发语言研发山东省海岛管理信息系统。 山东省是我国海岛资源比较丰富的省份。从整体来看，山东省海岛地理位置优越，气候条件好，海岛类型分为基岩岛、沙岛和人工岛，其中大部分海岛为基岩岛，沙岛主要分布在黄河三角洲北侧的滨州和潍坊昌邑。山东省海岛拥有丰富的渔业资源、水产资源、旅游资源、土地资源、港口资源、地下卤水资源、贝壳砂资源等，依据这些资源优势，海岛的开发也集中在养殖业开发、旅游开发、港口资源开发等。 Geodatabase数据模型能够有效地定义、组织空间数据，ArcSDE技术提供了空间数据存储在商业关系型数据库的通道，Geodatabase数据模型和ArcSDE技术使得使用同一大型的关系型数据库统一存储空间数据和属性数据成为可能。本文采用Geodatabase数据模型、ArcSDE技术、SQL Server数据库，设计了海岛数据的统一存储和管理模型，通过数据处理和入库建立了山东省海岛空间数据库。 本文还基于GIS软件平台ArcEngine组件和程序开发语言VB.NET完成了山东省海岛管理信息系统的开发。该系统实现了海岛数据的访问和加载、海岛地图的显示和操作、海岛数据的多种方式的查询显示、地图的几何量算功能以及海岛专题资料的集成与综合分析，同时系统也提供数据图层的标注、图层颜色的设置，图层的移动、删除功能。这些功能的实现对山东省海岛的开发、管理提供了有用的平台，为决策部门提供服务。

Micro-systems for Optical Protein-Chip

Protein-Chip as micro-assays for the determination of protein interaction, the analysis, the identification and the purification of proteins has large potential applications. The Optical Protein-Chip is able to detect the multi-interaction of proteins and multi-bio-activities of molecules directly and simultaneously with no labeling. The chip is a small matrix on solid substrate containing multi-micro-area prepared by microfabrication with photolithography or soft lithography for surface patterning, and processed with surface modification which includes the physical, chemical, and bio-chemical modifications, etc. The ligand immobilization, such as protein immobilization, especially the oriented immobilization with low steric hindrance and high bio-specific binding activity between ligand and receptor is used to form a sensing surface. Each area of the pattern is corresponding to only one bioactivity. The interval between the areas is non-bioactive and optically extinctive. The affinity between proteins is used to realize non-labeling microassays for the determination of protein identification and protein interaction. The sampling of the chip is non-disturbing, performed with imaging ellipsometry and image processing on a database of proteins.

Heteroclinic cycles in lattice dynamical systems

A criterion of spatial chaos occurring in lattice dynamical systems-heteroclinic cycle-is discussed. It is proved that if the system has asymptotically stable heteroclinic cycle, then it has asymptotically stable homoclinic point which implies spatial chaos.

Numerical analysis of spatial evolution of the small signal gain in a chemical oxygen-iodine laser operating without primary buffer gas

A chemical oxygen iodine laser (COIL) that operates without primary buffer gas has become a new way of facilitating the compact integration of laser systems. To clarify the properties of spatial gain distribution, three-dimensional (3-D) computational fluid dynamics (CFD) technology was used to study the mixing and reactive flow in a COIL nozzle with an interleaving jet configuration in the supersonic section. The results show that the molecular iodine fraction in the secondary flow has a notable effect on the spatial distribution of the small signal gain. The rich iodine condition produces some negative gain regions along the jet trajectory, while the lean iodine condition slows down the development of the gain in the streamwise direction. It is also found that the new configuration of an interleaving jet helps form a reasonable gain field under appropriate operation conditions. (c) 2007 Elsevier Ltd. All rights reserved.