12389317
Methodical restructuring of complex workflow activities
We describe a family of activity-split and activity-join operations with a notion of validity. The key idea of introducing the set of activity-split and activity-join operations is to allow users to restructure ongoing activities in anticipation of uncertainty so that any significant performance loss due to unexpected unavailablity or delay of shared resources can be avoided or reduced through release of early committed resources or transferring ownership of uncommitted resources. To guarantee the correctness of new activities generated by activity-split or activity-join operations, we define the notion of validity of activity restructuring operations and identify the cases where the correctness is ensured and the cases where activity-split or activity-join are illegal due to the inconsistency incurred.
12589406
VISTA: Validating and Refining Clusters Via Visualization
Clustering is an important technique for understanding of large multidimensional datasets. Most of clustering research to date has been focused on developing automatic clustering algorithms and cluster validation methods. The automatic algorithms are known to work well in dealing with clusters of regular shapes, for example, compact spherical shapes, but may incur higher error rates when dealing with arbitrarily shaped clusters. Although some efforts have been devoted to addressing the problem of skewed datasets, the problem of handling clusters with irregular shapes is still in its infancy, especially in terms of dimensionality of the datasets and the precision of the clustering results considered. Not surprisingly, the statistical indices works ineffective in validating clusters of irregular shapes, too. In this paper, we address the problem of clustering and validating arbitrarily shaped clusters with a visual framework (VISTA). The main idea of the VISTA approach is to capitalize on the power of visualization and interactive feedbacks to encourage domain experts to participate in the clustering revision and clustering validation process. The VISTA system has two unique features. First, it implements a linear and reliable visualization model to interactively visualize multi-dimensional datasets in a 2D star-coordinate space. Second, it provides a rich set of user-friendly interactive rendering operations, allowing users to validate and refine the cluster structure based on their visual experience as well as their domain knowledge.
33902172
An Object-Centered Approach for Manipulating Hierarchically Complex Objects
We present an object-centered approach for manipulating hierarchically complex objects, which covers an extended object model and an object-centered query algebra. Extensions of the object model are mainly based on a separation of structural and semantic elements in modeling complex objects, including a general distinction between aggregation reference and association reference, an introduction of type inheritance into aggregation hierarchies and a support for combination of aggregation inheritance with subtype inheritance. Based on the extensions, we develop a query algebra as an integral part of the model. Unlike most of existing algebra-based query languages, our object algebra takes complex object collectively as a unit of high level queries and allows complex objects to be accessed at all levels of aggregation hierarchies without having resort to any kind of path expressions. Features of aggregation hierarchies, such as acyclicity and aggregation inheritance, have played important roles in such a development. We have also formally described the output type of each operator in order for dynamic classification of query results in the IsA type/class lattice. Although the design is based on the chosen object-oriented model, other object-oriented databases are possible. We feel that the proposal largely covers the query requirements for complex objects, and meanwhile provides users with an opportunity to remain within the framework of the model of complex objects while querying database. As a consequence, the flexibility and adaptability of the object-oriented model against schema changes are increased.
599285
Differential evaluation of continual queries
We define continual queries as a useful tool for monitoring of updated information. Continual queries are standing queries that monitor the source data and notify the users whenever new data matches the query. In addition to periodic refresh, continual queries include Epsilon Transaction concepts to allow users to specify query refresh based on the magnitude of updates. To support efficient processing of continual queries, we propose a differential re-evaluation algorithm (DRA), which exploits the structure and information contained in both the query expressions and the database update operations. The DRA design can be seen as a synthesis of previous research on differential files, incremental view maintenance, and active databases.
9143242
Update Monitoring: The CQ Project
In rapidly growing open environments such as the Internet, users experience information starvation in the midst of data overload, due to difficulties similar to finding the needle in a haystack. Update monitoring is a promising area of research where we bring the right information to the user at the right time, instead of forcing the user through manual browsing or repeated submission of queries. As an example of update monitoring research, we outline our work in the Continual Queries (CQ) project, including its basic concepts, software architecture, and current implementation status.
13182282
InfoFilter: Supporting quality of service for fresh information delivery
With the explosive growth of the Internet and World Wide Web comes a dramatic increase in the number of users that compete for the shared resources of distributed system environments. Most implementations of application servers and distributed search software do not distinguish among requests to different web pages. This has the implication that the behavior of application servers is quite unpredictable. Applications that require timely delivery of fresh information consequently suffer the most in such competitive environments. This paper presents a model of quality of service (QoS) and the design of a QoS-enabled information delivery system that implements such a QoS model. The goal of this development is two-fold. On one hand, we want to enable users or applications to specify the desired quality of service requirements for their requests so that application-aware QoS adaptation is supported throughout the Web query and search processing. On the other hand, we want to enable an application server to customize how it should respond to external requests by setting priorities among query requests and allocating server resources using adaptive QoS control mechanisms. We introduce the Infopipe approach as the systems support architecture and underlying technology for building a QoS-enabled distributed system for fresh information delivery.
17865149
A framework for specification-based class testing
Class testing is the base of object-oriented software testing. It involves three aspects: testing each method, testing the relations among class methods and testing the inheriting relation between class and subclass. Rather than concerning the whole class testing process, most specification-based class testing focuses on the methods of generating test cases from the class specification. As a result, the class testing process and test cases cannot be unified and managed in a consistent and convenient way. This paper introduces a test class framework (TCF) that is used to structure the test cases and test deriving process of the class under testing. This framework clearly denotes the process of deriving test cases and test suites from a class specification. It facilitates the construction and management of test cases. Object-Z notation is used to express the framework and class specification.
17203041
Tight upper bounds for cell loss probabilities in ATM multiplexers and required bandwidth estimation
Estimating the cell loss probability in an ATM multiplexer is a key issue in network management and traffic control such as call admission control and bandwidth allocation. In this paper, we derive a new approximation to estimate the total and individual cell loss probabilities in an ATM multiplexer fed by a superposition of heterogeneous on-off sources with exponentially distributed on and off periods. Based on this approximation, a simple and accurate method is proposed to estimate the aggregate required bandwidth by a given mix of traffic to guarantee a given cell loss probability.
8796534
Intelligent OCR Processing
Optical Character Recognition (OCR) has become a highly demanded information transfer technology in recent years. This demand has been driven by the increasing needs for information sharing and office automation, and by the increasing accessibility to largescale, fast, and powerful computer resources. A problem of current OCR technology is that texts produced by the state-of-the-art OCR software contain an unacceptable frequency of errors. This prevents the OCR technology from being efficiently used for vast-volume information transfer or daily office operation applications. To correct these errors in a conventional way requires a significant amount of costly human-machine interaction. In this article, we identify and classify the types and distributions of optical recognition errors. We propose a novel postprocessing strategy, based on machine learning techniques, to correct errors resulted from unrecognized or misrecognized characters during the recognition process. By applying this strategy, the accuracy of recognition can be significantly improved, and the human interaction required can be dramatically reduced. Experimental results indicate that, in a typical environment, about 46% of total errors can be corrected automatically (i.e., without human interference), with an accuracy of 91%.
17453773
Automatic 3D to 2D registration for the photorealistic rendering of urban scenes
This paper presents a novel and efficient algorithm for the 3D range to 2D image registration problem in urban scene settings. Our input is a set of unregistered 3D range scans and a set of unregistered and uncalibrated 2D images of the scene. The 3D range scans and 2D images capture real scenes in extremely high detail. A new automated algorithm calibrates each 2D image and computes an optimized transformation between the 2D images and 3D range scans. This transformation is based on a match of 3D with 2D features that maximizes an overlap criterion. Our algorithm attacks the hard 3D range to 2D image registration problem in a systematic, efficient, and automatic way. Images captured by a high-resolution 2D camera, that moves and adjusts freely, are mapped on a centimeter-accurate 3D model of the scene providing photorealistic renderings of high quality. We present results from experiments in three different urban settings.
18066023
Improvement on vertex cover for low-degree graphs
The Vertex Cover problem (given a graph G and an integer k, decide if G has a vertex cover of k vertices) is one of the six “basic” NP-complete problems according to Garey and Johnson [7]. It is fixed-parameter tractable in terms of Downey and Fellows [5], that is, it can be solved in time O(f(k)n), where f is a function of the parameter k but independent of the input length n and c is a constant independent of the parameter k. Continuous efforts have been made in improving fixed-parameter tractable algorithms for the vertex cover problem, starting from Buss’ algorithm of running time O(kn + 2kk2k+2) [2]. Downey and Fellows [4] developed an O(kn + 2kk2) time algorithm. More recently, Balasubramanian et al. [1] developed an O(kn+1.3247kk2) time algorithm. Later Downey et al. [6] improved the result slightly to time complexity O(kn + 1.3195kk2), and Niedermeier and Rossmanith [9] developed an algorithm of time O(kn+1.2918kk2). More recently, Chen et al. [3] developed an O(kn + 1.271kk2) time algorithm. For the restricted version of the vertex