74 research outputs found
Evaluation of a chemocapacitive sensor array for the detection of vapor analytes and their mixtures
No full textAdaptive workflow processing and execution in Pegasus
No full textWorkflows are widely used in applications that require coordinated use of computational resources. Workflow definition languages typically abstract over some aspects of the way in which a workflow is to be executed, such as the level of parallelism to be used or the physical resources to be deployed. As a result, a workflow management system has the responsibility of establishing how best to execute a workflow given the available resources. The Pegasus workflow management system compiles abstract workflows into concrete execution plans, and has been widely used in large-scale e-Science applications. This paper describes an extension to Pegasus whereby resource allocation decisions are revised during workflow evaluation, in the light of feedback on the performance of jobs at runtime. The contributions of this paper include: (i) a description of how adaptive processing has been retrofitted to an existing workflow management system; (ii) a scheduling algorithm that allocates resources based on runtime performance; and (iii) an experimental evaluation of the resulting infrastructure using grid middleware over clusters
Light cycle oil solvent extraction optimization: Impact of solvent, temperature, and solvent to feed ratio variation
No full textA Management System for Service level Agreements in Grid based Systems
No full textGrid based systems have increased the opportunity for users to deploy and execute their applications using Grid resources. These resources have varying reliability and performability, particularly when demand is high. If a Grid application is executed at such times, performance may suffer and results may be delayed. In order to overcome this problem, application management is needed to support Quality of Service (QoS) requirements. The Distributed Aircraft Maintenance Environment (DAME) is an example of a Grid based system in which users wish to attach application QoS requirements.
In light of this, an adaptive SLA (Service Level Agreement) management system is presented which has the ability to interpret application requirements and deliver management using application adaptation. An SLA specification is presented which improves contract non-repudiation by way of elements which allow requirements, guarantees to be specified and provenance to be recorded. To predict the execution time of an application, a technique using historical observations is proposed. An approach which is highly appropriate for Grid based systems which perform countless runs of the same application. This prediction is used in combination with application monitoring to determine the progress made by the application during run-time. Progress is determined by comparing an estimate of the applications remaining execution time and an execution schedule. If application progress is insufficient, a rule-based control algorithm monitors progress and infers control actions which adapt the behaviour of the application.
Experimental analysis is conducted on a local Grid test-bed and a large scale Grid infrastructure, the White Rose Grid. This shows the solution supports application executions with attached time or performance constraints; where use of the system prevents application failure or delay. Migration is useful in reducing the execution time of applications when performance degradation occurs. Mechanisms for automated monitoring and provenance capture are presented, both of which support the operation of the SLA management system.
Adaptive SLA management benefits the users of Grid based systems such as DAME, by providing Grid application management. This is in contrast to current best-effort provision which offers no such guarantee. The ability to provide these guarantees and an SLA specification makes commercial exploitation of these Grid based systems more realisti
Um gerador de programas para sistemas de regras de produção visando a eficiencia na execução
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro TecnologicoEsta dissertação apresenta o SPP, um Sistema de Produção Proporcional desenvolvido com características adequadas para sua utilização em aplicações de tempo real, embora possa ser igualmente usado para outro tipo de aplicações. O SPP é implementado como um gerador de programa, têmuma sintaxe lisp-like e uma boa capacidade matemática. Requer a declaração explícita de atributos e funções, está baseado na lógica proporcional e sua máquina de inferência trabalha sem backtracking, com raciocínio não monotônico, em encadeamento para frente e atendendo as estratégias clássicas de resolução de conflitos. Para conseguir uma boa eficiência de execução, a linguagem C foi escolhida como base do desenvolvimento, sendo usada tanto para o sistema especialista gerado como para o programa gerador. Por outro lado, uma interface ampla e flexível entre SPP e a linguagem C insere o sistema num contexto de programação híbrida (mistura de procedural e não procedural), necessário para compatibilizar o tempo real com os sistemas especialistas
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