411372
Stratification Approach to Modeling Video
The explosive growth of audiovisual information in the last few years has made the development of advanced video modeling and management tools an urgent task. In this research, we investigate the use of stratification approach to model the contextual information of video contents as multi-layered strata. By judiciously choosing the right level and types of strata, we are able to automate a major part of the strata extraction process. Using the strata as the basis, we have developed advanced functionalities to support the flexible retrieval and content-based browsing of video. A prototype has been developed to support the whole process of video management, from strata extraction, to indexing, retrieval and browsing. The prototype is tested in the domain of news video and the system has been found to be effective.
2673173
State Aware Data Dissemination over Structured Overlays
We describe the problem of data dissemination in stream-oriented applications where the required filter is a function of the current state. We call such functions dynamic filters. A state aware data dissemination network (SA-DDN) is proposed to support dynamic filters. Two approaches single-level filtering (SF) and multilevel filter decomposition (MFD) are proposed to facilitate the data dissemination. We show how MFD improves performance over SF. We then describe a realization of SA-DDN on top of an improved bi-directional Chord overlay with a built-in multicast mechanism. An application of stock price monitoring is implemented based on SA-DDN and real life stock quotes are collected to demonstrate the feasibility of our system. Extensive simulations are performed to compare the performance of both approaches and provide insight into the advantages of MFD
3172403
On overlay schemes to support point-in-range queries for scalable grid resource discovery
A resource directory is a critical component of a grid architecture. P2P computing paradigm could address some of the scalability issues that make distributed resource discovery services challenging. Unfortunately, most existing distributed hash table (DHT) based P2P overlays have difficulty in treating attribute range queries that are common in resource discovery lookups. This paper proposes a general framework for range-based resource discovery. In particular, the proposed framework maps tree-structured logical data (i.e., range indexing) onto a DHT-based physical node space (i.e., resource brokers). In this paper, we consider three mapping schemes from the logical space onto the physical space. Each mapping scheme uses a different replication mechanism to reduce range search time and to achieve load balance. We analytically and experimentally compare the performance characteristics (query/update costs and workload distributions) of these schemes and discuss their applicability under different resource discovery service scenarios.
6721638
Adaptive video streaming in vertical handoff: a case study
Video streaming has become a popular form of transferring video over the Internet. With the emergence of mobile computing needs, a successful video streaming solution demands 1) uninterrupted services even with the presence of mobility and 2) adaptive video delivery according to current link properties. We study the need and evaluate the performance of adaptive video streaming in vertical handoff scenarios. We use universal seamless handoff architecture (USHA) to create a seamless handoff environment, and use the video transfer protocol (VTP) to adapt video streaming rates according to "eligible rate estimates". Using testbed measurements experiments, we verify the importance of service adaptation, as well as show the improvement of user-perceived video quality, via adapting video streaming in the vertical handoffs.
10568129
The HIV positive selection mutation database
The HIV positive selection mutation database is a large-scale database available at that provides detailed selection pressure maps of HIV protease and reverse transcriptase, both of which are molecular targets of antiretroviral therapy. This database makes available for the first time a very large HIV sequence dataset (sequences from ∼50 000 clinical AIDS samples, generously contributed by Specialty Laboratories, Inc.), which makes possible high-resolution selection pressure mapping. It provides information about not only the selection pressure on individual sites but also how selection pressure at one site is affected by mutations on other sites. It also includes datasets from other public databases, namely the Stanford HIV database [S. Y. Rhee, M. J. Gonzales, R. Kantor, B. J. Betts, J. Ravela and R. W. Shafer (2003) Nucleic Acids Res., 31, 298–303]. Comparison between these datasets in the database enables cross-validation with independent datasets and also specific evaluation of the effect of drug treatment.
4781375
SERFing the web: The Re-Web approach for web re-structuring
In our emerging digital paper-less society, massive amount of information is being maintained in on-line repositories and diverse web site representations of this information must be served over the Internet to different user groups. E-commerce and digital libraries are two representative sample applications with such needs. In this paper we present a database-centric approach called Re-Web that addresses this need for flexible web site generation, re-structuring, and maintenance. Re-Web is based on two key ideas. First, we exploit the web site structure by associating web semantics (XML equivalents) with the modeling constructs of the ODMG object model to aid the web site generation process. By capturing the logical structure of web views within the OODB system, we can efficiently maintain the web views using standard database techniques. Secondly, to ease the process of specification and construction of multiple customized web view sites, we also propose the notion of generic web view transformations that are encapsulated into re-usable templates. Thus desired new web view sites can be generated simply by applying the corresponding transformations on the underlying database to produce web view classes and then by applying the web semantics on the newly built view classes. The Re-Web system has been implemented using PSE by Object Design Inc. as object repository, ODMG as object model, OQL as transformation language, SERF as OODB evolution facility and IBM XML parser and LotusXSL processor to aid the web site generation. A case study using Re-Web is also presented to illustrate the working of the system. To the best of our knowledge, Re-Web is the first web site management system focusing on the issue of re-usable view generation templates at the content and not at the presentation style level of abstraction.
9226100
Mining Positive and Negative Association Rules from XML Query Patterns for Caching
Recently, several approaches that mine frequent XML query patterns and cache their results have been proposed to improve query response time. However, frequent XML query patterns mined by these approaches ignore the temporal sequence between user queries. In this paper, we take into account the temporal features of user queries to discover association rules, which indicate that when a user inquires some information from the XML document, she/he will probably inquire some other information subsequently. We cluster XML queries according to their semantics first and then mine association rules between the clusters. Moreover, not only positive but also negative association rules are discovered to design the appropriate cache replacement strategy. The experimental results showed that our approach considerably improved the caching performance by significantly reducing the query response time.
1252625
Supporting self-adaptation in streaming data mining applications
There are many application classes where the users are flexible with respect to the output quality. At the same time, there are other constraints, such as the need for real-time or interactive response, which are more crucial. This paper presents and evaluates a runtime algorithm for supporting adaptive execution for such applications. The particular domain we target is distributed data mining on streaming data. This work has been done in the context of a middleware system called GATES (grid-based adaptive execution on streams) that we have been developing. The self-adaptation algorithm we present and evaluate in this paper has the following characteristics. First, it carefully evaluates the long-term load at each processing stage. It considers different possibilities for the load at a processing stage and its next stages, and decides if the value of an adaptation parameter needs to be modified, and if so, in which direction. To find the ideal new value of an adaptation parameter, it performs a binary search on the specified range of the parameter. To evaluate the self-adaptation algorithm in our middleware, we have implemented two streaming data mining applications. The main observations from our experiments are as follows. First, our algorithm is able to quickly converge to stable values of the adaptation parameter, for different data arrival rates, and independent of the specified initial value. Second, in a dynamic environment, the algorithm is able to adapt the processing rapidly. Finally, in both static and dynamic environments, the algorithm clearly outperforms the algorithm described in our earlier work and an obvious alternative, which is based on linear-updates.