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An Index mechanism for multi-scale view in spatial databases 认领 引用
1
作者 ZHANGYuan-zhi XIEKun-qing +2 位作者 MAXiu-jun LIChen-yu CHENZhuo 《重庆邮电学院学报（自然科学版）》 2004年第5期16-22,共7页
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should ... There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations: retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R tree. The difference between the generalization and the R tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value, too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub blocks, and vertexes are total ordered by their importance value. With the help of the generalized R tree, one can easily retrieve data at different detail levels. Some experiments are performed on real life data to evaluate the performance of solutions that separately use normal spatial index and multi scale spatial index. The results show that the solution using multi scale index in SISP is satisfying. 展开更多
关键词 索引机制 空间数据库 多级观察 R树 可见性 选择性 简单性
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A solution of spatial query processing and query optimization for spatial databases 认领 引用
2
作者 YUANJie XIEKun-qing +2 位作者 MAXiu-jun ZHANGMin SUNLe-bin 《重庆邮电学院学报（自然科学版）》 2004年第5期165-172,共8页
Recently, attention has been focused on spatial query language which is used to query spatial databases. A design of spatial query language has been presented in this paper by extending the standard relational databas... Recently, attention has been focused on spatial query language which is used to query spatial databases. A design of spatial query language has been presented in this paper by extending the standard relational database query language SQL. It recognizes the significantly different requirements of spatial data handling and overcomes the inherent problems of the application of conventional database query languages. This design is based on an extended spatial data model, including the spatial data types and the spatial operators on them. The processing and optimization of spatial queries have also been discussed in this design. In the end, an implementation of this design is given in a spatial query subsystem. 展开更多
关键词 空间数据库 询问语言 空间数据模型 空间操作 最优化
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CX11: A Chinese Language Supporting Interface for X Window Environment 认领 引用
3
作者 熊志国 徐曦 董士海 《Journal of Computer Science & Technology》 SCIE EI 1995年第1期15-22,共8页
HChinese language deals with ideographic character input and output. TheX Window System (X11R5 or earlier versions) has the mechanism to outputHanzi (Chinese ideograph) through 2-byte encoding when the correspondingfo... HChinese language deals with ideographic character input and output. TheX Window System (X11R5 or earlier versions) has the mechanism to outputHanzi (Chinese ideograph) through 2-byte encoding when the correspondingfolits are included, but it has no corresponding input feature. Because thereare as many as 16000 most in use Hanzis, more than one keystroke is needed toinput a single Hanzi by the traditional English keyboard. This paper proposesa Hanzi input architecture on the X Window System and a Chinese languagemechanism that can upgrade English-based commercial X products or supplyan appIication (X clients) programming interface for inputting Hanzi. CX11,our first implementation, is running on SCO ODT. Its design principle andimplementation should be a model and can be applied as one of the generalapproaches to inteInationalize and localize the X Window System. 展开更多
关键词 X Window System internationalization localization Chinese ideograph (Hanzi) multibyte encoding
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Exploiting Deterministic TPG for Path Delay Testing 认领 引用 被引量：1
4
作者 李晓维 PaulY.S.Cheung 《Journal of Computer Science & Technology》 SCIE EI 2000年第5期472-479,共8页
Detection of path delay faults requires two-pattern tests. BIST technique provides a low-cost test solution. This paper proposes an approach to designing a cost-effective deterministic test pattern generator (TPG) for... Detection of path delay faults requires two-pattern tests. BIST technique provides a low-cost test solution. This paper proposes an approach to designing a cost-effective deterministic test pattern generator (TPG) for path delay testing. Given a set of pre-generated test-pairs with pre-determined fault coverage, a deterministic TPG is synthesized to apply the given test-pair set in a limited test time. To achieve this objective, configurable linear feedback shift register (LFSR) structures are used. Techniques are developed to synthesize such a TPG, which is used to generate an unordered deterministic test-pair set. The resulting TPG is very efficient in terms of hardware size and speed performance. Simulation of academic benchmark circuits has given good results when compared to alternative solutions. 展开更多
关键词 built-in self-test (BIST) path delay testing deterministic TPG configurable LFSR
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Outline of Initial Design of the Structured Hypertext Transfer Protocol 认领 引用
5
作者 孙斌 《Journal of Computer Science & Technology》 SCIE EI 2003年第3期287-298,共12页
This paper presents an introduction to the initial design of the Structured Hyper-text Transfer Protocol (STTP), a compatible extension to the HTTP. It includes a new message setfor the control of resource transmissio... This paper presents an introduction to the initial design of the Structured Hyper-text Transfer Protocol (STTP), a compatible extension to the HTTP. It includes a new message setfor the control of resource transmission, and the Structured Hypertext Markup Language (STML)for describing the structural information of Web pages. Experimental tests show that STTP canbe significantly faster than HTTP, with the improvement of transmission time being around 70%to 400% and the same magnitude of packet savings, which is among the best performance improve-ment ever reported. The paper discusses the basic idea and major design considerations of thesecomponents, as well as a few important issues in developing STTP servers and clients. 展开更多
关键词 HTTP 环球网 性能 超文本 传送方法 初始设计 传输协议
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