5900836
The TV-tree: An index structure for high-dimensional data
We propose a file structure to index high-dimensionality data, which are typically points in some feature space. The idea is to use only a few of the features, using additional features only when the additional discriminatory power is absolutely necessary. We present in detail the design of our tree structure and the associated algorithms that handle such “varying length” feature vectors. Finally, we report simulation results, comparing the proposed structure with theR*-tree, which is one of the most successful methods for low-dimensionality spaces.The results illustrate the superiority of our method, which saves up to 80% in disk accesses.
7539391
Compressed-domain video indexing techniques using DCT and motion vector information in MPEG video
Development of various multimedia applications hinges on the availability of fast and efficient storage, browsing, indexing, and retrieval techniques. Given that video is typically stored efficiently in a compressed format, if we can analyze the compressed representation directly, we can avoid the costly overhead of decompressing and operating at the pixel level. Compressed domain parsing of video has been presented in earlier work where a video clip is divided into shots, subshots, and scenes. In this paper, we describe key frame selection, feature extraction, and indexing and retrieval techniques that are directly applicable to MPEG compressed video. We develop a frame-type independent representation of the various types of frames present in an MPEG video in which al frames can be considered equivalent. Features are derived from the available DCT, macroblock, and motion vector information and mapped to a low-dimensional space where they can be accessed with standard database techniques. The spatial information is used as primary index while the temporal information is used to enhance the robustness of the system during the retrieval process. The techniques presented enable fast archiving, indexing, and retrieval of video. Our operational prototype typically takes a fraction of a second to retrieve similar video scenes from our database, with over 95% success.
18266651
A similarity-based soft clustering algorithm for documents
Document clustering is an important tool for applications such as Web search engines. Clustering documents enables the user to have a good overall view of the information contained in the documents that he has. However, existing algorithms suffer from various aspects, hard clustering algorithms (where each document belongs to exactly one cluster) cannot detect the multiple themes of a document, while soft clustering algorithms (where each document can belong to multiple clusters) are usually inefficient. We propose SISC (similarity-based soft clustering), an efficient soft clustering algorithm based on a given similarity measure. SISC requires only a similarity measure for clustering and uses randomization to help make the clustering efficient. Comparison with existing hard clustering algorithms like K-means and its variants shows that SISC is both effective and efficient.
17442336
Ordinal association rules for error identification in data sets
A new extension of the Boolean association rules, ordinal association rules, that incorporates ordinal relationships among data items, is introduced. One use for ordinal rules is to identify possible errors in data. A method that finds these rules and identifies potential errors in data is proposed.
18594508
An index structure for efficient reverse nearest neighbor queries
The Reverse Nearest Neighbor (RNN) problem is to find all points in a given data set whose nearest neighbor is a given query point. Just like the Nearest Neighbor (NN) queries, the RNN queries appear in many practical situations such as marketing and resource management. Thus, efficient methods for the RNN queries in databases are required. The paper introduces a new index structure, the Rdnn-tree, that answers both RNN and NN queries efficiently. A single index structure is employed for a dynamic database, in contrast to the use of multiple indexes in previous work. This leads to significant savings in dynamically maintaining the index structure. The Rdnn-tree outperforms existing methods in various aspects. Experiments on both synthetic and real world data show that our index structure outperforms previous methods by a significant margin (more than 90% in terms of number of leaf nodes accessed) in RNN queries. It also shows improvement in NN queries over standard techniques. Furthermore, performance in insertion and deletion is significantly enhanced by the ability to combine multiple queries (NN and RNN) in one traversal of the tree. These facts make our index structure extremely preferable in both static and dynamic cases.
46019766
A Study on Textual Entailment
In this paper we study a graph-based approach to the task of textual entailment between a text and hypothesis. The approach takes into account the full lexico-syntactic context of both the text and hypothesis and relies heavily on the concept of subsumption. It starts with mapping the text and hypothesis into graph structures where nodes represent concepts and edges represent lexico-syntactic relations among concepts. Based on a subsumption score between the text-graph and hypothesis-graph an entailment decision is then made. The impact of synonymy on entailment is quantified and discussed. An important advantage of our solution is the ability to customize it so that high-confidence results are obtained
15828117
Enhancing external consistency in real-time transactions
Real-time computing brings two new requirements to database management. The first is the deadline constraint which requires better scheduling algorithms to meet transaction deadfines. The second requirement is the temporal validity, or external consistency[Lin89], requirement of data: a real-time database must prevent data from being corrupted not only by the executions of concurrent transactions but also by the delay from sharing computing resources and real-time scheduler decisions. In this paper, we study the external consistency requirement in real-time databases. We propose a semantic-based concurrency control scheme that prefers the external consistency to the traditional serializability. Two new concepts are introduced in our work. An update of a physical object value is considered to be compatible to those read operations that need to access the most recent data. Secondly, if a transaction depends strongly on the validity of the value of an object, a new update may cause the transaction to be aborted since continuing the transaction may be harmful to the appfication. A real-Life example is the stock market database. A trading program may be executed for a long time and its read operations should not block any new updates. Moreover, if there is a big sudden change in a particular stock price, it may be better to abort an on-going transaction rather than letting it make some invalid decisions.
44711812
An open real-time environment for parallel and distributed systems
Most computer-based systems have hard real-time constraints. Schedulers in complex systems must be designed to manage a set of applications developed and deployed independently. We study an open real-time environment architecture for distributed systems where real-time applications may run concurrently with non-real-time applications. The architecture uses a two-level scheduling scheme. Each application is assigned a sporadic server to schedule the processes in the application. All sporadic servers are then scheduled by a system-wide fixed priority scheduler. Using the proposed open environment architecture, all hard real-time applications are guaranteed to have their reserved CPU utilization in order to meet all their deadlines. The guarantee is independent of the behaviors of all other applications in the same system. We present the schedulability analysis methods on systems with or without shared memory.
9933111
Service-oriented computing
Service-oriented computing using Web services has emerged as a major research topic in recent years. Strong support from major computer companies including IBM, Microsoft, Hewlett-Packard, Oracle, and SAP has accelerated the acceptance and adoption of SOC using Web services. With SOC, enterprises can define and execute transactions across multiple business. Companies can use SOC's plug-and-play interoperability to compose business processes and integrate different information systems on the fly to enable ad hoc cooperation between new partners. Thus, SOC reinvents the way enterprises work together: common tasks in a business process or supply chain can be easily outsourced to external service providers for both performance and cost reasons.
14548816
Enhancing the real-time capability of the Linux kernel
Linux has become one of the most popular UNIX operating systems. Commercial support for Linux and adoption of Linux in real world applications have now started to emerge. Some of the applications have strict real-time requirements. We discuss how to make Linux a real-time operating system. The real-time capability is achieved by three new kernel mechanisms. We port a microtimer into the kernel. We adopt the time-driven scheduling paradigm and implement a time-driven scheduler in the Linux kernel. Finally, we insert preemption points in the kernel to make it more preemptable so that real-time jobs may experience shorter blockings. Our approach is general and may be used to enhance the real-time capability of other non-real-time operating systems as well.
40285763
Critical Points for Interactive Schema Matching
Experience suggests that fully automated schema matching is infeasible, especially for n-to-m matches involving semantic functions. It is therefore advisable for a matching algorithm not only to do as much as possible automatically, but also to accurately identify the critical points where user input is maximally useful. Our matching algorithm combines several existing approaches, with a new emphasis on using the context provided by the way elements are embedded in paths. A prototype tested on biological data (gene sequence, DNA, RNA, etc.) and on bibliographic data, shows significant performance improvements from user feedback and context checking. In non-interactive mode on the purchase order schemas, it compares favorably with COMA, the most mature schema matching system in literature, and also correctly identifies critical points for user input.