Extending and Relating Semantic Models of Compensating CSP

Business transactions involve multiple partners coordinating and interacting with each other. These transactions have hierarchies of activities which need to be orchestrated. Usual database approaches (e.g.,checkpoint, rollback) are not applicable to handle faults in a long running transaction due to interaction with multiple partners. The compensation mechanism handles faults that can arise in a long running transaction. Based on the framework of Hoare's CSP process algebra, Butler et al introduced Compensating CSP (cCSP), a language to model long-running transactions. The language introduces a method to declare a transaction as a process and it has constructs for orchestration of compensation. Butler et al also defines a trace semantics for cCSP. In this thesis, the semantic models of compensating CSP are extended by defining an operational semantics, describing how the state of a program changes during its execution. The semantics is encoded into Prolog to animate the specification. The semantic models are further extended to define the synchronisation of processes. The notion of partial behaviour is defined to model the behaviour of deadlock that arises during process synchronisation. A correspondence relationship is then defined between the semantic models and proved by using structural induction. Proving the correspondence means that any of the presentation can be accepted as a primary definition of the meaning of the language and each definition can be used correctly at different times, and for different purposes. The semantic models and their relationships are mechanised by using the theorem prover PVS. The semantic models are embedded in PVS by using Shallow embedding. The relationships between semantic models are proved by mutual structural induction. The mechanisation overcomes the problems in hand proofs and improves the scalability of the approach

Extending and relating semantic models of compensating CSP

Business transactions involve multiple partners coordinating and interacting with each other. These transactions have hierarchies of activities which need to be orchestrated. Usual database approaches (e.g.,checkpoint, rollback) are not applicable to handle faults in a long running transaction due to interaction with multiple partners. The compensation mechanism handles faults that can arise in a long running transaction. Based on the framework of Hoare's CSP process algebra, Butler et al introduced Compensating CSP (cCSP), a language to model long-running transactions. The language introduces a method to declare a transaction as a process and it has constructs for orchestration of compensation. Butler et al also defines a trace semantics for cCSP. In this thesis, the semantic models of compensating CSP are extended by defining an operational semantics, describing how the state of a program changes during its execution. The semantics is encoded into Prolog to animate the specification. The semantic models are further extended to define the synchronisation of processes. The notion of partial behaviour is defined to model the behaviour of deadlock that arises during process synchronisation. A correspondence relationship is then defined between the semantic models and proved by using structural induction. Proving the correspondence means that any of the presentation can be accepted as a primary definition of the meaning of the language and each definition can be used correctly at different times, and for different purposes. The semantic models and their relationships are mechanised by using the theorem prover PVS. The semantic models are embedded in PVS by using Shallow embedding. The relationships between semantic models are proved by mutual structural induction. The mechanisation overcomes the problems in hand proofs and improves the scalability of the approach.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Verification of Symmetry Detection using PVS

One of the major limitations of model checking is that of state-space explosion. Symmetry reduction is a method that has been successfully used to alleviate this problem for models of systems that consist of sets of identical components. In earlier work, we have introduced a specification language, Promela-Lite, which captures the essential features of Promela but has a fully defined semantics. We used hand proofs to show that a static symmetry detection technique developed for this language is sound, and suitable to be used in a symmetry reduction tool for SPIN. One of the criticisms often levelled at verification implementations, is that they have not been proved mechanically to be correct, i.e., no mechanical formal verification technique has been used to check the soundness of the approach. In this paper, we address this issue by mechanically verifying the correctness of the symmetry detection technique. We do this by embedding the syntax and semantics of Promela-Lite into the theorem prover PVS and using these embeddings to both check the consistency of syntax/semantics definitions, and interactively prove relevant theoretical properties

An investigation of carbon sequestration/ECBM potential in Australian coals: a simulation study for Sydney Coal Basin

A 2002 report by Australian National Greenhouse Gas Inventory suggests that since 1990 Australia's net emissions of carbon dioxide equivalent from stationary combustion sources are on the rise and they are likely to rise even at a higher rate in keeping with continued economic and industrial growth. In order to reduce Australian CO₂emissions, there is a need to identify and explore large-capacity storage locations for CO₂ sequestration. In that context, Australian coal seams, notably the coal-bed methane (CBM) reservoirs in Sydney and Bowen Basins, could potentially be attractive sites to sequester large volumes of greenhouse CO₂ emissions while also recovering the methane gas, a relatively cleaner source of fossil fuel. This study investigates the deliverability and economic feasibility of CO₂ sequestration through CO₂-Enhanced CBM recovery (CO₂-ECBMR) in the Camden area, Sydney coal basin. The results of the study show that the CO₂-ECBMR impacts the absolute pelmeability of the Camden area significantly. Because of a good reticulated fracture system, the CO₂ breakthrough from the producers is faster. The enhancement of CH₄ recovery by preferential adsorption of CO₂ occurs simultaneously with the abatement of CH₄ recovery by overall decrease in permeability in the CBM reservoir. Hence, the actual CH₄ is produced under the overall effect of these two competing processes, with the operating parameters like producer-injector spacing and injection pressure affecting their relative dominance over each other. The study also addresses the opportunities of a niche for CO₂ sequestration in these coals, which will be dictated mainly by the factors of sequestration economics and status of these coals being "unmineable". The results derived from the study could help the design of an optimum operating strategy in implementing the CO₂ sequestration and enhanced CBM recovery in Sydney Basin, Australia and elsewhere.Thesis (Ph.D.) -- University of Adelaide, Australian School of Petroleum, 200