FlowUML is a logic-based system to validate information flow policies at the requirements specification phase of UML based designs. It uses Horn clauses to specify information flow polices that can be checked against ...
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The increasing heterogeneity, dynamism, and uncertainty of emerging DCE (Distributed Computing Environment) systems imply that an application must be able to detect and adapt to changes in its state, its requirements,...
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Achieving acceptable quality of service in highly dynamic computing environments requires not only adaptation and reconfiguration of individual components of the system, but also collaboration among these components. ...
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Achieving acceptable quality of service in highly dynamic computing environments requires not only adaptation and reconfiguration of individual components of the system, but also collaboration among these components. To address these issues in adaptive multimedia applications, we propose COCA, a contract-based collaborative adaptation infrastructure. COCA uses contract specifications to describe the relationships among different system components, to generate code that realizes adaptive functionality, and to govern system-wide adaptive behavior during execution. COCA also provides a set of reusable adaptation services that enable legacy components to be integrated into an adaptive system. We demonstrate the use of COCA to construct an adaptive multimedia conferencing system from a collection of existing components that were not originally designed for interoperation.
We present a simple, local protocol, pCover, which provides partial (but high) coverage in sensor networks. Through pCover, we demonstrate that it is feasible to maintain a high coverage (~90%) while significantly inc...
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We present a simple, local protocol, pCover, which provides partial (but high) coverage in sensor networks. Through pCover, we demonstrate that it is feasible to maintain a high coverage (~90%) while significantly increasing coverage duration when compared with protocols that provide full coverage. In particular, we show that we are able to maintain 94% coverage for a duration that is 2.3-7 times the duration for which existing protocols maintain full coverage. Through simulations, we show that our protocol provides load balancing, i.e., the desired level of coverage is maintained (almost) until the point where all sensors deplete their batteries
In previous years, many studies have been conducted on grid computing, in which users and resource providers organize various virtual organizations (VOs) to share resources and services. A VO organizes other sub-VOs f...
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In previous years, many studies have been conducted on grid computing, in which users and resource providers organize various virtual organizations (VOs) to share resources and services. A VO organizes other sub-VOs for the purpose of achieving the VO goal, which forms the hierarchical VO environment. In this paper, we model and formalize the resource allocation problem in hierarchical VOs. Resource providers and VOs agree upon the VO resource sharing policy, such as resource sharing amount and resource usage cost for VOs. We provide the resource allocation scheme of a VO resource broker to minimize the total cost in order to meet a user's job deadline. In addition, we deal with several cost adjustment methods in resource providers to utilize their resources efficiently in hierarchical VOs
Evacuation planning plays a significant role in building evacuation. The purpose of this paper is to demonstrate how an evolutionary computation technique in the form of an estimation of distribution algorithm can be ...
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Evacuation planning plays a significant role in building evacuation. The purpose of this paper is to demonstrate how an evolutionary computation technique in the form of an estimation of distribution algorithm can be used in evacuation planning. This technique is used to evolve the number and location of exits in order to minimize overall evacuation time and reduce the number of casualties and injuries. The algorithm is applied to three day-care layouts, classified as playroom, lunchroom, and classroom settings. The algorithm generates an optimal or near-optimal configuration, and results across several trials can be used to determine the probability that an exit is needed for each possible location. The best exit configurations are presented for each of the three layouts, and a brief analysis is discussed. Although evacuation planning presented in this paper is focused on room layouts, evolutionary computation techniques have the potential to be implemented in large-scale evacuation planning
Sensor Webs are heterogeneous collections of sensor devices that collect information and interact with the environment. They consist of wireless sensor networks that are ensembles of small, smart, and cheap sensing an...
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Sensor Webs are heterogeneous collections of sensor devices that collect information and interact with the environment. They consist of wireless sensor networks that are ensembles of small, smart, and cheap sensing and computing devices that permeate the environment as well as high-bandwidth rich sensors such as satellite imaging systems, meteorological stations, air quality stations, and security cameras. Emergency response, homeland security, and many other applications have a very real need to interconnect such diverse networks and access information in real-time. While Internet protocols and Web standards provide well-developed mechanisms for accessing this information, linking such mechanisms with resource-constrained sensor networks is very challenging because of the volatility of the communication links. This paper presents a service-oriented programming model for sensor networks which permits discovery and access of Web services. Sensor network applications are realized as graphs of modular and autonomous services with well-defined interfaces that allow them to be described, published, discovered, and invoked over the network providing a convenient way for integrating services from heterogeneous sensor systems. Our approach provides dynamic discovery, composition, and binding of services based on an efficient localized constraint satisfaction algorithm that can be used for developing ambient-aware applications that adapt to changes in the environment. A tracking application that employs many inexpensive sensor nodes, as well as a Web service, is used to illustrate the approach. Our results demonstrate the feasibility of ambient-aware applications that interconnect wireless sensor networks and Web services.
Grid computing has emerged as an effective means of facilitating the sharing of distributed heterogeneous resources, enabling collaboration in large scale environments. However, the nature of grid systems coupled with...
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Grid computing has emerged as an effective means of facilitating the sharing of distributed heterogeneous resources, enabling collaboration in large scale environments. However, the nature of grid systems coupled with the overabundance and fragmentation of information, makes it difficult to monitor resources, services, and computations in order to plan and make decisions. In this paper we present Gridscape II, a customisable portal component that can be used on its own or plugged-in to compliment existing grid portals. Gridscape II manages the gathering of information from arbitrary, heterogeneous and distributed sources and presents them together seamlessly within a single interface. It also leverages the Google Maps API in order to provide a highly interactive user interface. Gridscape II is simple and easy to use, providing a solution to those users who do not wish to invest heavily in developing their own monitoring portal from scratch, and also for those users who want something easy to customise and extend for their specific needs
The advent of service-oriented grid computing has resulted in the need for grid resources such as clusters to enforce user-specific service needs and expectations. Service level agreements (SLAs) define conditions whi...
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The advent of service-oriented grid computing has resulted in the need for grid resources such as clusters to enforce user-specific service needs and expectations. Service level agreements (SLAs) define conditions which a cluster needs to fulfill for various jobs. An example of SLA requirement is the deadline by which a job has to be completed. In addition, these clusters implement job admission control so that overall service performance does not deteriorate due to accepting exceeding amount of jobs. However, their effectiveness is highly dependent on accurate runtime estimates of jobs. This paper thus examines the adverse impact of inaccurate runtime estimates for deadline constrained job admission control in clusters using the earliest deadline first (EDF) strategy and a deadline-based proportional processor share strategy called Libra. Simulation results show that an enhancement called LibraRisk can manage the risk of inaccurate runtime estimates better than EDF and Libra by considering the risk of deadline delay
This paper presents interfacing techniques to integrate a virtual environment (VE), computer graphics, image-based modeling, and other technologies in a networked system for robot control. Technologies such as network...
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