3410538
A Flexible Context-Aware Authorization Framework for Mediation Systems
Security is a critical concern for mediator-based data integration among heterogeneous data sources. This paper provides a modeling and architectural solution to the problem of mediation security that addresses the security challenges including context-awareness, semantic heterogeneity, and multiple security policy specification. A generic, extensible modeling method for the security policies in mediation systems is presented. A series of authorization constraints are identified based on the relationship on the different security components in the mediation systems. Moreover, we enforce the flexible access control to mediation systems while providing uniform access for heterogeneous data sources.
3393163
Dynamic Integration Strategy for Mediation Framework
The trend in the information area is to provide integrated access to diverse and dynamic information sources. We present a modeling and architectural solution to the problem of data integration from heterogeneous data sources based on the use of wrappers and mediators. The mediator supports integrated query processing by the semantic mapping between the global schema type and the local schema types. However, mediation poses extensive security problems. Protecting proprietary data from unauthorized access is recognized as one of the most significant barriers to the mediation systems. Our approach benefits in both flexible strategy of data integration based on semantic mappings and dynamic access control in mediation systems.
3857492
Formal Representation and Transformation of DTDs to Sem-ODM Semantic Schemas
Many projects have investigated the issue of storing XML in traditional database systems and exporting data in traditional databases as XML documents. However, they paid little attention to the formalization of the data models and transformation between them. In this paper, we address this problem by providing a formal framework in which Document Type Definition (DTD) and Semantic Schema of the Semantic Binary ObjectOriented Data Model (Sem-ODM) are formally defined and the conversion from DTD to Semantic Schema is presented. Through this formalization, we achieve preciseness and conciseness in expressing both data models and converting one to the other.
207735443
A fuzzy multi-objective programming for optimization of fire station locations through genetic algorithms
Abstract Location of fire stations is an important factor in its fire protection capability. This paper aims to determine the optimal location of fire station facilities. The proposed method is the combination of a fuzzy multi-objective programming and a genetic algorithm. The original fuzzy multiple objectives are appropriately converted to a single unified ‘min–max’ goal, which makes it easy to apply a genetic algorithm for the problem solving. Compared with the existing methods of fire station location our approach has three distinguish features: (1) considering fuzzy nature of a decision maker (DM) in the location optimization model; (2) fully considering the demands for the facilities from the areas with various fire risk categories; (3) being more understandable and practical to DM. The case study was based on the data collected from the Derbyshire fire and rescue service and used to illustrate the application of the method for the optimization of fire station locations.
1693393
An Evaluation of Confidence Bound Estimation Methods for Neural Networks
When artificial neural networks (ANN) are used in prediction problems, it is usually desirable that some form of confidence bound is placed on the predicted value. Methods to estimate the confidence bound are available. However, these methods are valid under certain assumptions, which are rarely satisfied in practice. The behavior of the estimated confidence bound is not well understood when the assumptions are violated. We have designed some test functions to examine the behavior. The experimental results give us some guidelines on how the confidence estimation methods should be used in our application, which is to predict rock porosity values from seismic data for oil reservoir characterisation.
236427
Efficient XML query processing in mediators
With the advent of XML as the standard for data representation and exchange over the Internet, there are ever increasing applications; E-commerce application in particular, using XML as a mediator model. It raises the issue of how to evaluate XML queries efficiently in mediator systems. The authors address the problem of multiple query optimization in an XML based mediator. Because the XML query language differs from SQL/OQL in its pattern matching and regular path expression constructs, the method of identifying common subexpressions of multiple XML queries is different accordingly. We present the steps to identify common subexpressions. To obtain the global query plan, we propose some heuristics to reduce the whole search space. By using a statistical method to estimate the usage frequency of the common subexpressions in XML queries, a selective caching and materializing of remote data can be accurately made, and this will greatly improve query response time.
6650910
A predictive, decentralized load balancing approach
The growth of load balancing system raises the issue of scalability, and decentralized load balancing architecture has been proposed to address this issue. In this paper, we investigate how a load balancing architecture can be built on decentralized policies based on CORBA and enhanced by predictive algorithm. The L/sub 2/E predictive filtering model was used to supply workstations with robust cluster load information, which allows them to make more accurate independent allocation decisions. Experimental results showed that our decentralized load balancing approach was able to suppress thrashing and oscillations compared to other load monitoring and prediction techniques, and it was able to achieve a highly balanced system than Sun Grid Engine.