A theory for execution-time derivation in real-time programs

We provide an abstract command language for real-time programs and outline how a partial correctness semantics can be used to compute execution times. The notions of a timed command, refinement of a timed command, the command traversal condition, and the worst-case and best-case execution time of a command are formally introduced and investigated with the help of an underlying weakest liberal precondition semantics. The central result is a theory for the computation of worst-case and best-case execution times from the underlying semantics based on supremum and infimum calculations. The framework is applied to the analysis of a message transmitter program and its implementation. (c) 2005 Elsevier B.V. All rights reserved.

On the execution of collaborative business processes

Management of collaborative business processes that span multiple business entities has emerged as a key requirement for business success. These processes are embedded in sets of rules describing complex message-based interactions between parties such that if a logical expression defined on the set of received messages is satisfied, one or more outgoing messages are dispatched. The execution of these processes presents significant challenges since each contentrich message may contribute towards the evaluation of multiple expressions in different ways and the sequence of message arrival cannot be predicted. These challenges must be overcome in order to develop an efficient execution strategy for collaborative processes in an intensive operating environment with a large number of rules and very high throughput of messages. In this paper, we present a discussion on issues relevant to the evaluation of such expressions and describe a basic query-based method for this purpose, including suggested indexes for improved performance. We conclude by identifying several potential future research directions in this area. © 2010 IEEE. All rights reserved

Implementation of a triple modular redundant FPGA based safety critical system for reliable software execution

This paper describes the implementation of a TMR (Triple Modular Redundant) microprocessor system on a FPGA. The system exhibits true redundancy in that three instances of the same processor system (both software and hardware) are executed in parallel. The described system uses software to control external peripherals and a voter is used to output correct results. An error indication is asserted whenever two of the three outputs match or all three outputs disagree. The software has been implemented to conform to a particular safety critical coding guideline/standard which is popular in industry. The system was verified by injecting various faults into it.

DOS MUROS DA ESCOLA À ABERTURA PARA A CIDADE

A prática educativa na escola está carregada de uma postura tradicional e bancária , conforme aparece em várias obras de Freire, ainda que novas tecnologias sejam introduzidas em seu cotidiano pedagógico. A ênfase à informação em detrimento da construção do conhecimento e saberes, na verdade, afasta o aluno, particularmente nas escolas públicas, de apropriar-se dos instrumentos significativos de sua elaboração. Nesse sentido, dentro da linha de Políticas e Gestões Educacionais, esse trabalho se propõe à reflexão do espaço da escola no diálogo com a cidade, isto é, à possibilidade de protagonismo social no desenvolvimento do aluno. O procedimento da pesquisa fundamenta-se no estudo dos projetos de educação ambiental desenvolvidos na rede municipal de Mauá através dos registros e relatos descritivos das avaliações das escolas dessas atividades, de seus Projetos Políticos Pedagógicos e do Programa de Educação Ambiental de Mauá da Secretaria Municipal de Educação. O trabalho Dos muros da escola à abertura para a cidade foi desenvolvido de forma a entendermos o espaço geográfico, considerando sua territorialização e o conceito de espaço simbólico. Dessa forma, podemos compreender como a relação escola/espaço território e o Programa de Educação Ambiental desenvolvido em escolas da rede pública da cidade de Mauá aparece na atuação de um em relação ao outro. A metodologia de trabalho usada foi exploratória, de natureza bibliográfica e documental. A pesquisa buscou perceber a abordagem dialógica que se estabelece com a cidade a partir da conceituação do espaço simbólico da escola no processo ensino-aprendizagem. O Programa de Educação Ambiental e as escolas, de acordo com seus Projetos Políticos Pedagógicos se propõem, ainda que empiricamente, a trabalhar nessa direção. A prática pedagógica, como demonstraram algumas atividades, mesmo tratando do tema de forma sem a consciência diferenciada , aponta um avanço nesse sentido. Os textos coletivos, a participação solidária, são elementos que nos permitem concluir dessa forma. As respostas das crianças foram significativas, embora tenhamos apontado as dificuldades na execução dos procedimentos pedagógicos. Por tratar-se de algo novo, não só como proposta, o Programa de Educação Ambiental exigiu a capacidade de lidar com ações integrada e integradora, ou seja, mudança de subjetividade dos distintos atores envolvidos no processo. O tema poderia se tornar por demais abrangente e, dessa forma, perder-se em generalidades. Assim, alguns aspectos relevantes foram apontados sem, no entanto, partir para um maior aprofundamento a fim de garantir a objetividade do trabalho. A instituição escolar está presente de corpo e alma na cidade e, ainda que, a temática ambiental esteja presente em seu cotidiano ela se faz de maneira formal e informativa. Todos falam em meio ambiente, entretanto poucos internalizam os valores de um ambiente saudável e próprio para o desenvolvimento humano da maioria que produz a riqueza das nações. Consideradas as observações apontadas, o trabalho apresentou elementos que devem ser analisados com maior propriedade, isto é, com maior extensão, como proposta de continuidade da pesquisa.

Intelligent execution monitoring and error analysis in planning involving processes

An intelligent agent, operating in an external world which cannot be fully described in its internal world model, must be able to monitor the success of a previously generated plan and to respond to any errors which may have occurred. The process of error analysis requires the ability to reason in an expert fashion about time and about processes occurring in the world. Reasoning about time is needed to deal with causality. Reasoning about processes is needed since the direct effects of a plan action can be completely specified when the plan is generated, but the indirect effects cannot. For example, the action `open tap' leads with certainty to `tap open', whereas whether there will be a fluid flow and how long it might last is more difficult to predict. The majority of existing planning systems cannot handle these kinds of reasoning, thus limiting their usefulness. This thesis argues that both kinds of reasoning require a complex internal representation of the world. The use of Qualitative Process Theory and an interval-based representation of time are proposed as a representation scheme for such a world model. The planning system which was constructed has been tested on a set of realistic planning scenarios. It is shown that even simple planning problems, such as making a cup of coffee, require extensive reasoning if they are to be carried out successfully. The final Chapter concludes that the planning system described does allow the correct solution of planning problems involving complex side effects, which planners up to now have been unable to solve.

Prior action execution has no effect on corticospinal facilitation during action observation

Transcranial magnetic stimulation (TMS) has been used widely in research investigating corticospinal (CS) excitability during action observation. Generally, this work has shown that observation of an action performed by others, in the absence of overt movement, modulates the excitability of the CS pathway in humans. Despite the extent of the literature exploring action observation effects, however, there has been little research to date that has compared observation with the combination of observation and execution directly. Here, we report a single-pulse TMS study that investigated whether CS excitability during action observation was modulated by actions performed by the observers prior to viewing a ball pinching action. The results showed that CS excitability during action observation increased when compared to observation of a static hand, but that there was no additional motor facilitation when participants performed the same action prior to observing it. Our findings highlight the importance of action observation and its consequences on the CS system, whilst also illustrating the limited effect of prior action execution on the CS pathway for a simple action task.