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991.
Estimation of distributions involving unobservable events: the case of optimal search with unknown Target Distributions 总被引:1,自引:0,他引:1
We consider the problem of estimating the parameters of a distribution when the underlying events are themselves unobservable.
The aim of the exercise is to perform a task (for example, search a web-site or query a distributed database) based on a distribution
involving the state of nature, except that we are not allowed to observe the various “states of nature” involved in this phenomenon.
In particular, we concentrate on the task of searching for an object in a set of N locations (or bins) {C
1, C
2,…, C
N
}, in which the probability of the object being in the location C
i
is p
i
, where P = [p
1, p
2,…, p
N
]
T
is called the Target Distribution. Also, the probability of locating the object in the bin within a specified time, given that it is in the bin, is given by a function called the Detection function, which, in its most common instantiation, is typically, specified by an exponential function. The intention is to
allocate the available resources so as to maximize the probability of locating the object. The handicap, however, is that
the time allowed is limited, and thus the fact that the object is not located in bin C
i
within a specified time does not necessarily imply that the object is not in C
i
. This problem has applications in searching large databases, distributed databases, and the world-wide web, where the location
of the files sought for are unknown, and in developing various military and strategic policies. All of the research done in
this area has assumed the knowledge of the {p
i
}. In this paper we consider the problem of obtaining error bounds, estimating the Target Distribution, and allocating the
search times when the {p
i
} are unknown. To the best of our knowledge, these results are of a pioneering sort - they are the first available results
in this area, and are particularly interesting because, as mentioned earlier, the events concerning the Target Distribution,
in themselves, are unobservable.
Qingxin Zhu Qingxin Zhu got his Bachelor’s degree in Mathematics in 1981 from Sichuan Normal University, China. He got the Master’s degree in Applied Mathematics from Beijing Institute of Technology in 1984. From 1984 to 1988 he was employed by the Southwest Technical Physics Institute. In 1988, he continued his higher education with the Department of Mathematics, University of Ottawa, Canada and got a PhD degree in 1993. From 1993 to 1996, he did postgraduate research and got a second Master’s degree in Computer Science from Carleton University, Canada. He is currently a Professor with the University of Electronics Science and Technology of China (UESTC). His research interests are Optimal Search Theory, Computer Applications, and Bioinformatics. B. John Oommen Dr. John Oommen was born in Coonoor, India on 9 September 1953. He obtained his B.Tech. degree from the Indian Institute of Technology, Madras, India in 1975. He obtained his M.E. from the Indian Institute of Science in Bangalore, India in 1977. He then went on for his MS and PhD which he obtained from Purdue University, in West Lafayettte, Indiana in 1979 and 1982, respectively. He joined the School of Computer Science at Carleton University in Ottawa, Canada, in the 1981–1982 academic year. He is still at Carleton and holds the rank of a Full Professor. Since July 2006, he has been awarded the honorary rank of Chancellor's Professor, which is a lifetime award from Carleton University. His research interests include Automata Learning, Adaptive Data Structures, Statistical and Syntactic Pattern Recognition, Stochastic Algorithms and Partitioning Algorithms. He is the author of more than 280 refereed journal and conference publications, and is a Fellow of the IEEE and a Fellow of the IAPR. Dr. Oommen is on the Editorial Board of the IEEE Transactions on Systems, Man and Cybernetics, and Pattern Recognition. 相似文献
B. John Oommen (Corresponding author)Email: |
Qingxin Zhu Qingxin Zhu got his Bachelor’s degree in Mathematics in 1981 from Sichuan Normal University, China. He got the Master’s degree in Applied Mathematics from Beijing Institute of Technology in 1984. From 1984 to 1988 he was employed by the Southwest Technical Physics Institute. In 1988, he continued his higher education with the Department of Mathematics, University of Ottawa, Canada and got a PhD degree in 1993. From 1993 to 1996, he did postgraduate research and got a second Master’s degree in Computer Science from Carleton University, Canada. He is currently a Professor with the University of Electronics Science and Technology of China (UESTC). His research interests are Optimal Search Theory, Computer Applications, and Bioinformatics. B. John Oommen Dr. John Oommen was born in Coonoor, India on 9 September 1953. He obtained his B.Tech. degree from the Indian Institute of Technology, Madras, India in 1975. He obtained his M.E. from the Indian Institute of Science in Bangalore, India in 1977. He then went on for his MS and PhD which he obtained from Purdue University, in West Lafayettte, Indiana in 1979 and 1982, respectively. He joined the School of Computer Science at Carleton University in Ottawa, Canada, in the 1981–1982 academic year. He is still at Carleton and holds the rank of a Full Professor. Since July 2006, he has been awarded the honorary rank of Chancellor's Professor, which is a lifetime award from Carleton University. His research interests include Automata Learning, Adaptive Data Structures, Statistical and Syntactic Pattern Recognition, Stochastic Algorithms and Partitioning Algorithms. He is the author of more than 280 refereed journal and conference publications, and is a Fellow of the IEEE and a Fellow of the IAPR. Dr. Oommen is on the Editorial Board of the IEEE Transactions on Systems, Man and Cybernetics, and Pattern Recognition. 相似文献
992.
Semplore: A scalable IR approach to search the Web of Data 总被引:1,自引:0,他引:1
Haofen Wang Qiaoling Liu Thomas Penin Linyun Fu Lei Zhang Thanh Tran Yong Yu Yue Pan 《Journal of Web Semantics》2009,7(3):177-188
The Web of Data keeps growing rapidly. However, the full exploitation of this large amount of structured data faces numerous challenges like usability, scalability, imprecise information needs and data change. We present Semplore, an IR-based system that aims at addressing these issues. Semplore supports intuitive faceted search and complex queries both on text and structured data. It combines imprecise keyword search and precise structured query in a unified ranking scheme. Scalable query processing is supported by leveraging inverted indexes traditionally used in IR systems. This is combined with a novel block-based index structure to support efficient index update when data changes. The experimental results show that Semplore is an efficient and effective system for searching the Web of Data and can be used as a basic infrastructure for Web-scale Semantic Web search engines. 相似文献
993.
Harmony search based algorithm for the optimum design of grillage systems to LRFD-AISC 总被引:1,自引:1,他引:0
Harmony search based optimum design method is presented for the grillage systems. This numerical technique imitates the musical
performance process that takes place when a musician searches for a better state of harmony. Jazz improvisation seeks to find
musically pleasing harmony similar to the optimum design process which seeks to find the optimum solution. The design algorithm
considers the serviceability and ultimate strength constraints which are implemented from Load and Resistance Factor Design—American
Institute of Steel Construction (LRFD-AISC). It selects the appropriate W-sections for the transverse and longitudinal beams
of the grillage system out of 272 discrete W-section designations given in LRFD-AISC. This selection is carried out such that
the design limitations described in LRFD-AISC are satisfied and the weight of the system is the minimum. Many design examples
are considered to demonstrate the efficiency of the algorithm presented. 相似文献
994.
越权访问是基于Web系统普遍存在的问题,也是一个非常难解决的问题。以SGI服务器构建的Web系统为例,通过理论分析和实例讨论来解决越权访问这一棘手的问题,最终达到将来能构建更安全的Web系统的目的。 相似文献
995.
996.
Christoph Riedl Tilo Böhmann Michael Rosemann Helmut Krcmar 《Information Systems and E-Business Management》2009,7(2):199-221
Service-oriented architectures and Web services mature and have become more widely accepted and used by industry. This growing
adoption increased the demands for new ways of using Web service technology. Users start re-combining and mediating other
providers’ services in ways that have not been anticipated by their original provider. Within organisations and cross-organisational
communities, discoverable services are organised in repositories providing convenient access to adaptable end-to-end business
processes. This idea is captured in the term Service Ecosystem. This paper addresses the question of how quality management
can be performed in such service ecosystems. Service quality management is a key challenge when services are composed of a
dynamic set of heterogeneous sub-services from different service providers. This paper contributes to this important area
by developing a reference model of quality management in service ecosystems. We illustrate the application of the reference
model in an exploratory case study. With this case study, we show how the reference model helps to derive requirements for
the implementation and support of quality management in an exemplary service ecosystem in public administration. 相似文献
997.
基于模板法的网页英语试卷自动抽取技术的研究 总被引:1,自引:1,他引:0
为解决在线考试系统中建立海量数据库的问题,采用基于模板法的Web信息抽取方法,提取相似网页中的正文内容。并根据包含英文试卷的网页特点,制定正文抽取规则,最终可获得完整的英语试卷及其答案。实验结果表明,该方法具有较高的准确率和提取速度。 相似文献
998.
搜索引擎优化策略研究 总被引:1,自引:0,他引:1
随着Internet的发展及网络资源越来越丰富,搜索引擎所起的作用也越来越大。因此搜索引擎优化作为一种可以提升网站在搜索引擎中的排名的网站优化技术,得到了广泛的关注。如何获得高的搜索引擎排名对网站特别是商务网站显得越来越重要。文章对搜索引擎优化策略进行了系统的总结,讨论了一些具体的优化方法,并对搜索引擎优化的发展前景进行了展望。 相似文献
999.
通过结合网站设计初期的网站结构和典型用例的预先定义,构建一个基于Web日志数据的用户访问数据分析系统。该系统(AS-UAB,Analysis System of User Access Behaviors)通过对网站结构和典型用例的预先植入,利用该领域最新的研究方法和结论,为网站相关人员提供可视化的用户访问信息统计及趋势预测,网站结构设计及交互设计上存在的问题及改进建议等通用功能和个性化定制功能。 相似文献
1000.
通过对数字化校园网络应用传统统一身份认证和资源访问控制机制不足之处的分析,提出了一种基于Web服务的统一身份认证系统模型,并采用基于票据的集中式架构,以跨域Cookie共享为核心来完成用户的登录、认证和权限控制。实例证明,此方案可以方便的将分散网络节点加入认证体系,完成网络节点单点登录和资源访问控制问题。 相似文献