4779667
GBI: A Generalized R-Tree Bulk-Insertion Strategy
A lot of recent work has studied strategies related to bulk loading of large data sets into multidimensional index structures. In this paper, we address the problem of bulk insertions into existing index structures with particular focus on R-trees - which are an important class of index structures used widely in commercial database systems. We propose a new technique, which as opposed to the current technique of inserting data one by one, bulk inserts entire new incoming datasets into an active R-tree. This technique, called GBI (for Generalized Bulk Insertion), partitions the new datasets into sets of clusters and outliers, constructs an R-tree (small tree) from each cluster, identifies and prepares suitable locations in the original R-tree (large tree) for insertion, and lastly performs the insertions of the small trees and the outliers into the large tree in bulk. Our experimental studies demonstrate that GBI does especially well (over 200% better than the existing technique) for randomly located data as well as for real datasets that contain few natural clusters, while also consistently outperforming the alternate technique in all other circumstances.
4775385
A fine-grained replacement strategy for XML query cache
Caching popular queries and reusing results of previously computed queries is one important query optimization technique, especially in modern distributed environments such as the WWW. Based on the recent proliferation of XML data and the emergence of the XQuery language, we are thus developing a query- based caching system for XQuery queries, called ACE-XQ. ACE-XQ applies innovative query containment and rewriting strategies to answer incoming user queries based on the cached XQueries, whenever possible, instead of accessing remote XML data sources.To manage the space of the cache, a straightforward application of traditional replacement strategies would correspond to removing a complete cached query and its derived XML document as a whole when space needs to be freed. This coarse granularity however does not match well with the typical access pattern of web searches where new queries often partially overlap with cached queries.In this paper, we propose a novel replacement strategy appropriate for such query-based XML caching systems. In particular, we collect user access statistics at the granularity of the XML path structure instead of the complete XML query regions. We then apply a more fine-grained replacement strategy that purges XML fragments off a cached region instead of the whole XML document and accordingly adjusts the query descriptor. This may better capture the user access patterns since more frequently used XML document fragments are likely to remain in the cache while other less beneficial parts are purged. This approach has been implemented in our ACE-XQ System. Preliminary experiment results illustrate the performance improvement achievable by our fine-grained replacement strategy over the one which replaces a whole XML view at a time when the cache size is relatively large.
4784687
SERF: ODMG-based generic re-structuring facility
The age of information management and with it the advent of increasingly sophisticated technologies have kindled a need in the database community and others to re-structure existing systems and move forward to make use of these new technologies. Legacy application systems are being transformed to newer state-of-the-art systems, information sources are being mapped from one data model to another, a diversity of data sources are being transformed to load, cleanse and consolidate data into modern data-warehouses [CR99].
Re-structuring is thus a critical task for a variety of applications. For this reason, most object-oriented database systems (OODB) today support some form of re-structuring support [Tec94, Obj93, BKKK87]. This existing support of current OODBs [BKKK87, Tec94, Obj93] is limited to a pre-defined taxonomy of simple fixed-semantic schema evolution operations. However, such simple changes, typically to individual types only, are not sufficient for many advanced applications [Bré96]. More radical changes, such as combining two types of redefining the relationship between two types, are either very difficult or even impossible to achieve with current commercial database technology [Tec94, Obj93]. In fact, most OODBs would typically require the user to write ad-hoc programs to accomplish such transformations. Research that has begun to look into the issue of complex changes [Bré96, Ler96] is still limited by providing a fixed set of some selected (even if now more complex) operations.
To address these limitations of the current restructuring technology, we have proposed the SERF framework which aims at providing a rich environment for doing complex user-defined transformations flexibly, easily and correctly [CJR98b]. The goal of our work is to increase the usability and utility of the SERF framework and its applicability to re-structuring problems beyond OODB evolution. Towards that end, we provide re-usable transformations via the notion of SERF Templates that can be packaged into libraries, thereby increasing the portability of these transformations. We also now have a first cut at providing an assurance of consistency for the users of this system, a semantic optimizer that provides some performance improvements via enhanced query optimization techniques with emphasis on the re-structuring primitives [CNR99]. In this demo we give an overview of the SERF framework, its current status and the enhancements that are planned for the future. We also present an example of the application of SERF to a domain other than schema evolution, i.e., the web restructuring.
4773437
XCache: a semantic caching system for XML queries
A wide range of Web applications retrieve desired information from remote XML data sources across the Internet, which is usually costly due to transmission delays for large volumes of data. Therefore we propose to apply the ideas of semantic caching to XML query processing systems [2], in particular the XQuery engine. Semantic caching [3] implies view-based query answering and cache management. While it is well studied in the traditional database context, query containment for XQuery is left unexplored due to its complexity coming with the powerful expressiveness of hierarchy, recursion and result construction. We hence have developed the first solution for XQuery processing using cached views.We exploit the connections between XML and tree automata, and use subtype relations between two regular expression types to tackle the XQuery containment mapping problem. Inspired by XDuce [1], which explores the use of tree-automata-based regular expression types for XML processing, we have designed a containment mapping process to incorporate type inference and subtyping mechanisms provided by XDuce to establish containment mappings between regular-expression-type-based pattern variables of two queries. We have implemented a semantic caching system called XCache (see Figure 1), to realize the proposed containment and rewriting techniques for XQuery.The main modules of XCache include: (1) Query Decomposer. An input query is is decomposed into source-specific subqueries explicitly represented by matching patterns and return structures. (2) Query Pattern Register. By registering a few queries into semantic regions, we warm up XCache at its initialization phase. (3) Query Containment Mapper. The XDuce subtyper is incorporated into the containment mapper for establishing query containment mappings between variables of a new query and each cached query. (4) Query Rewriter. We implement the classical bucket algorithm and further apply heuristics to decide on an "optimal" rewriting plan if several valid ones exist. (5) Replacement Manager. We free space for new regions by both complete and partial replacement. (6) Region Coalescer. We apply a coalescing strategy to control the region granularity over time.
4779943
SERFing the Web: web site management made easy
In the era of electronic publishing, there is a need for a comprehensive Web Site Management System (WSMS) that provides an end-to-end solution ranging from integration of web sites to re-structuring and maintenance of new customized web views. Today, while many research efforts focus on generating diversified web sites, our Re-Web system [CRCK98] is the first to look at easing this process for end-users by providing libraries of pre-defined generic t ransformations for web re-structuring and visual tools for the generation and browsing of such transformations. Re-Web translates web information to an OO schema and data, re-structures and integrates information at the OODB level (SERF [CR99]) and finally generates web pages from the information in the database. The Re-Web system uses JDK1.2, Java Swing, and PSE Pro6.0 as its persistent storage. We use LotusXSL and IBM's XML parser for the web generation module. Re-Web system (Figure 1) has been implemented and tested on WinNT and Solaxis. I t provides tools for generating, restructuring and maintaining web sites.
4792658
Active Page Generation via Customizing XML for Data Beans in E-Commerce Applications
In this paper, we analyze enabling technologies for typical e-business applications in terms of their multi-tier system architecture and their Model-Control-View (MCV) programming model. Based on observed limitations of the JSP (Java Server Page) technique commonly adopted for dynamic page generation (the view logic), we instead propose an alternative solution approach, namely, a generic schema mapping strategy to generate XML documents and DTDs from enterprise data beans. First, we describe in detail the XML generation process for the content composition logic. We also outline the XSL processing for the transformation logic. The separation of these two logics results in a generic solution to the bean viewing problem. In particular, it improves the bean reusability via its XML representative compared to the rigid strategy of hard-coding logics into JSP. Our proposed XML mapping solution represents a potentially valuable addition to future versions of the enterprise data beans specification. The trade-off between performance and flexibility of these alternative solutions is discussed. Lastly, we survey the state-of-art research results and emerging stardards related to this XML model mapping approach.
12599093
A scalable software-based self-test methodology for programmable processors
Software-based self-test (SBST) is an emerging approach to address the challenges of high-quality, at-speed test for complex programmable processors and systems-on chips (SoCs) that contain them. While early work on SBST has proposed several promising ideas, many challenges remain in applying SBST to realistic embedded processors. We propose a systematic scalable methodology for SBST that automates several key steps. The proposed methodology consists of (i) identifying test program templates that are well suited for test delivery to each module within the processor, (ii) extracting input/output mapping functions that capture the controllability/observability constraints imposed by a test program template for a specific module-under-test, (iii) generating module-level tests by representing the input/output mapping functions as virtual constraint circuits, and (iv) automatic synthesis of a software self-test program from the module-level tests. We propose novel RTL simulation-based techniques for template ranking and selection, and techniques based on the theory of statistical regression for extraction of input/output mapping functions. An important advantage of the proposed techniques is their scalability, which is necessitated by the significant and growing complexity of embedded processors.To demonstrate the utility of the proposed methodology, we have applied it to a commercial state-of-the-art embedded processor (Xtensa™ from Tensilica Inc.). We believe this is the first practical demonstration of software-based self-test on a processor of such complexity. Experimental results demonstrate that software self-test programs generated using the proposed methodology are able to detect most (95.2%) of the functionally testable faults, and achieve significant simultaneous improvements in fault coverage and test length compared with conventional functional test.
6274371
Trust building with explanation interfaces
Based on our recent work on the development of a trust model for recommender agents and a qualitative survey, we explore the potential of building users' trust with explanation interfaces. We present the major results from the survey, which provided a roadmap identifying the most promising areas for investigating design issues for trust-inducing interfaces. We then describe a set of general principles derived from an in-depth examination of various design dimensions for constructing explanation interfaces, which most contribute to trust formation. We present results of a significant-scale user study, which indicate that the organization-based explanation is highly effective in building users' trust in the recommendation interface, with the benefit of increasing users' intention to return to the agent and save cognitive effort.
8727184
Estimating Link Capacity in High Speed Networks
Knowledge of bottleneck capacity of an Internet path is critical for efficient network design, management, and usage. With emerging high speed Internet links, most traditional estimation techniques are limited in providing fast and accurate capacity estimations. In this paper, we propose a new technique, called PBProbe, to estimate high speed links. PBProbe is based on CapProbe; however, instead of solely relying on packet pairs, PBProbe employs a “packet bulk” technique and adapts the bulk length in order to overcome the well known problem with packet pair based approaches, namely the lack of accurate timer resolution. As a result, PBProbe not only preserves the simplicity and speed of CapProbe, but it also correctly estimates link capacities within a much larger range. Using analysis, we evaluate PBProbe with various bulk lengths and network configurations. We then perform emulation and Internet experiments to verify the accuracy and speed of PBProbe on high speed links. The results show that PBProbe is consistently fast and accurate in the great majority of test cases.
10396270
Temporal Shot Clustering Analysis for Video Concept Detection
The phenomenon that conceptually related shots appear together in videos is called temporal shot clustering. This phenomenon is a useful cue for video concept detection, which is one of basic steps in content-based video indexing and retrieval. We propose a method, called temporal shot clustering analysis, to improve results of video concept detection by exploiting the temporal shot clustering phenomenon. Two other methods are compared with temporal shot clustering analysis on the TRECVID 2003 dataset. Experiments showed that temporal shot clustering is of much benefit for video concept detection, and that temporal shot clustering method outperforms the other methods.
10243856
A new LDA-based face recognition system which can solve the small sample size problem
A new LDA-based face recognition system is presented in this paper. Linear discriminant analysis (LDA) is one of the most popular linear projection techniques for feature extraction. The major drawback of applying LDA is that it may encounter the small sample size problem. In this paper, we propose a new LDA-based technique which can solve the small sample size problem. We also prove that the most expressive vectors derived in the null space of the within-class scatter matrix using principal component analysis (PCA) are equal to the optimal discriminant vectors derived in the original space using LDA. The experimental results show that the new LDA process improves the performance of a face recognition system signi"cantly. ( 2000 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.