Research on Data Service Model of DistributedHeterogeneous Database Information Sharing Technology

随着计算机和网络技术的发展，基于Internet的资源集成和共享已经成为当前主要的研究内容。Internet上存在着大量异构的数据资源，由于技术和管理的原因，形成了数据壁垒，数据的共享能力很低，网络上大量的数据资源形成了众多的“数据孤岛”，造成了Internet上资源丰富，信息匮乏的局面。异构数据库信息共享技术是针对在现代网络环境中如何在异构的数据环境下进行数据访问、信息共享问题的研究，具有很强的现实意义。本文讨论了异构数据库信息共享技术的主要解决方案，分析了联邦数据库模式、Wrapper/Mediator模式、中间件模式、数据仓库模式、WebService模式和数据网格模式在数据共享与集成解...With the rapid development of computer and network techniques,the research of resource integration and sharing based on Internet becomes the important and key subjects.There are lots of heterogeneous data sources in the Internet,due to techniques and management,data sources are isolated,data sharing becomes very difficult.More and more “data isolated islands” fromed in the Internet.Although there ...学位：工学硕士院系专业：计算机与信息工程学院计算机科学系_计算机应用技术学号：X200128027

Research on Grid Database Materialized Query Caching Policy

提出了基于XML Database的网格数据库物化查询缓存机制,提高用户查询的速度,均衡网格负载。定义了网格数据库服务质量与数据质量的标准,提出了物化查询选择算法MQS,为用户提供更好的数据服务。In this paper,grid database materialized query caching policy based on XML Database is presented,which will improve the response time of queries and balance the load of the grid.QoS and QoD of grid database are defined to provide parameters.The MQS algorithm acts as cached materialized query selector to provide better data service.福建省自然基金资助项目(A0310008);; 福建省高新技术研究开放计划重点资助项目(2003H043

电子政务基础数据库建设和信息服务研究

电子政务的目标是实现以“Citizen-centered”为宗旨的新的服务型政府。建设的中心问题是数据资源的共享与办公流程的优化重组。基础数据库的建设是电子政务建设的基础,基于基础数据库的信息服务是政府办公透明化的保障,也是电子政务向公众提供服务的重要手段。讨论了电子政务建设中的基础数据库建设问题和信息服务系统的结构和应用

Progress in research of hypoxia in estuaries and coastal areas in China

对长江、珠江等河口及其近海水域缺氧现象与影响因素进行研究,结果表明,主要分布于长江与珠江河口及其邻近海域的缺氧现象,夏季(6-8月)达到最盛,秋; 冬季消失;长江口的缺氧区域主要位于30.75°N~32°N,122.5°E~123.25°E附近海域,具有南北2个缺氧中心;珠江口缺氧程度相对较; 轻,缺氧区域主要在广州黄埔区河段至虎门水域和伶仃洋;辽河、钱塘江、海河等河口区域也时而出现零星的缺氧现象;水体缺氧受控于多项环境要素,物理层化作; 用是缺氧产生的最初诱因之一,陆源污染物的分解则是重要的耗氧负荷;各河口区特征各异,潮汐、洋流、营养盐、叶绿素a等要素对缺氧区的范围、程度和持续时; 间影响程度不一。In order to study hypoxia in the main estuaries and adjacent coastal; areas in China, we compared the hypoxia in the estuaries of the Yangtze; River, the Pearl River, and other rivers, and analyzed the factors. We; found that hypoxia mainly occurred in the estuaries of the Yangtze; River, the Pearl River, and the adjacent coastal areas; it had the most; significant increase in the summer (from June to August) and disappeared; in the autumn and winter. The hypoxia zone in the Yangtze River Estuary; was mainly located in the area with latitudes from 30.75°N to 32°N and; longitudes from 122.5°E to 123.25°E, and there were two hypoxia centers; in the south and north, respectively. The degree of hypoxia in the Pearl; River Estuary was relatively moderate, and hypoxia mainly occurred from; the Huangpu section to Humen waters in Guangzhou and in the Lingdingyang; Channel. In addition, hypoxia occasionally occurred in the estuaries of; the Liaohe River, Qiantang River, and Haihe River. We also found that; hypoxia was subjected to many environmental factors, of which the; stratification of water was one of the initial factors and the; decomposition of terrigenous pollutants was a major factor of oxygen; consumption. Tides, upwellings, nutrients, and chlorophyll-a had; different influences on the scale, degree, and duration of hypoxia, due; to the various characteristics of the estuaries

闽江下游及河口溶解无机氮的季节分布及组成

为研究闽江下游及河口区溶解无机氮（DIN）的季节分布及组成,采集并分析了四季的表层水样。平面分布上,NO3-N不同季节有所不同;NH4-N及NO2-N不同季节分布特征基本一致,仓山区、鼓楼区附近的站位受城市污水影响而含量偏高。季节变化上,NO3-N南北段春季最高,河口段冬季最高;NH4-N南北段秋季远高于其它三个季节,河口段季节变化不大;NO2-N南北段及河口段季节变化不大。DIN组成上,南北段不同季节占比相似,DIN组成上未达到热力学平衡;河口段DIN组成季节变化不大,三态间基本达到热力学平衡。DIN[2]转化上,北段三氮之间相关性总体较弱,且与DO的相关性变化较大,三氮关系受复杂的来源、人类活动及生物化学过程影响;南段三氮之间的相关性较显著也较复杂;河口段三氮及DO之间的关系季节差异比较明显。此外,闽江下游及河口DIN年际增高及超标现象较严重。国家自然科学基金(41376050

The Research on Dynamic Read/Write Replication Strategies of Data Grid

探讨了在网格环境中数据复制的相关策略,包括动态只读复制策略和动态读/写复制策略。动态复制策略可以用来减少带宽消耗和访问延迟,不同的复制策略在不同的访问方式下有不同的性能表现。同时,提出了动态读/写复制策略的Fast Upload算法,算法支持数据传输过程中的并发复制,通过复制锁机制来维护复制与更新数据的一致性。In this paper, the replica strategies are discussed, including Dynamic read-only Replication Strategies and Dynamic read/write Replication Strategy. Dynamic Replication Strategies can reduce bandwidth consumption and access latency in accessing the huge amounts of data. The Dynamic read/write Replication Strategy named as "Fast Upload" is proposed. Fast Upload enables updating while data transporting, and the replica lock mechanism ensures the consistency of the data source and different replica.福建省自然基金(A0310008);; 福建省高新技术研究开放计划重点项目资助(2003H043

Research on Programming of Basis Database Construction of E-government

在信息技术与现代网络技术的支持下,政府要为公众提供更加方便的高质量服务.通过将各个政府部门整合成单一的"虚拟政府",为公众提供"一站式"的政务服务.基础数据库作为电子政务建设中基础信息建设的内容,是实现信息共享的关键.本文讨论了基础数据库建设中所涉及的相关问题和建设与发展策略.The government needs higher quality service with the support of information technology and network technology. The "Virtue Government" should provide One-Stop service to the public. The basis database construction is the key component of Information share between different departments. In this paper, basis database construction and strategy are discussed

ODS Solution of the Coherence Matter in E-government

讨论了ODS技术在电子政务系统中的应用.将ODS引入到电子政务系统中形成更为合理的DB ODS DW3层结构,并通过ODS记录系统和参考表的使用进行全局联机事务处理,使各业务数据库内容可以实时更新,保持数据的一致性.从根本上解决密切相关的业务数据库数据不一致的问题.In this paper,ODS was used to solve the coherence matter in E-government solution, the three-tire structure of DB-ODS-DW will be more suitable to the E-government solution.Using the record system and the reference table,data in different DB would be dynamic update.The ODS system also provides different levels of update strategies and tactical analysis system to support analysis and decision