Can Component/Service-Based Systems Be Proved Correct?

Component-oriented and service-oriented approaches have gained a strong enthusiasm in industries and academia with a particular interest for service-oriented approaches. A component is a software entity with given functionalities, made available by a provider, and used to build other application within which it is integrated. The service concept and its use in web-based application development have a huge impact on reuse practices. Accordingly a considerable part of software architectures is influenced; these architectures are moving towards service-oriented architectures. Therefore applications (re)use services that are available elsewhere and many applications interact, without knowing each other, using services available via service servers and their published interfaces and functionalities. Industries propose, through various consortium, languages, technologies and standards. More academic works are also undertaken concerning semantics and formalisation of components and service-based systems. We consider here both streams of works in order to raise research concerns that will help in building quality software. Are there new challenging problems with respect to service-based software construction? Besides, what are the links and the advances compared to distributed systems?Comment: 16 page

Semantic Embedding of Petri Nets into Event-B

We present an embedding of Petri nets into B abstract systems. The embedding is achieved by translating both the static structure (modelling aspect) and the evolution semantics of Petri nets. The static structure of a Petri-net is captured within a B abstract system through a graph structure. This abstract system is then included in another abstract system which captures the evolution semantics of Petri-nets. The evolution semantics results in some B events depending on the chosen policies: basic nets or high level Petri nets. The current embedding enables one to use conjointly Petri nets and Event-B in the same system development, but at different steps and for various analysis.Comment: 16 pages, 3 figure

Comparison of membrane bioreactor technology and conventional activated sludge system for treating bleached kraft mill effluent

The purpose of this paper was to review the use of membrane bioreactor technology as an alternative for treating the discharged effluent from a bleached kraft mill by comparing and contrasting membrane bioreactors with conventional activated sludge systems for wastewater treatment. There are many water shortage problems currently in the world, some of which are more serious than others. Public concern over health and the environment, combined with increased requirements for municipalities to reuse wastewater, have created a need for new technologies that can treat wastewater to generate high quality reusable water at low cost. In several of these technologies, membrane technology could make a great contribution since membranes have the ability to produce water of exceptional purity that can be recycled for reuse in a variety of places. This reuse of wastewater is already widely practiced in many countries, which reduces net demand on water supply systems. In industry, in particular the pulp and paper industry, large volumes of water are used with a significant amount of wastewater generated. This effluent needs to be treated prior to final disposal or reuse. The commonly used biological treatment methods of aerated lagoons and activated sludge of bleached kraft mill effluent have been found to be inadequate in achieving the desired level of toxicity removal. There is, therefore, the growing demand for greener/sustainable technologies for reuse/recycling of wastewater and the membrane bioreactors treatment of these effluents has shown some greater potential as it is much cleaner and meet stringent discharge requirements than with other techniques.Key words: Membrane bioreactor, activated sludge, bleached kraft mill effluent, pulp and paper

Tool-Assisted Multi-Facet Analysis of Formal Specifications (Using Alelier-B and ProB).

International audienceTool-assisted analysis of software systems and convenient guides to practise the formal methods are still motivating challenges. This article addresses these challenges. We ex periment on analysing a formal specification from multiple aspects. The B method and the Atelier-B tool are used for formal specifications, for safety property analysis and for refinements. The ProB tool is used to supplement the study with model checking; it helps to discover errors and there fore to improve the former specifications

Modelling and Analysing Dynamic Decentralised Systems

We introduce a method to specify and analyse decentralised dynamic systems; the method is based on the combination of an event-based multi-process system specification approach with a multi-facet analysis approach that considers a reference abstract model and several specific ones derived from the abstract model in order to support facet-wise analysis. The method is illustrated with the modelling and the analysis of a mobile ad-hoc network. The Event-B framework and its related tools B4free and ProB are used to conduct the experiments.Comment: 6 pages - two columns (IEEE) - Conference PRDC'200

Submicroscopic Cracking of Cement Paste and Mortar in Compression

Submicroscopic cracking of cement paste and mortar under uniaxial compression is measured and correlated with applied strain and load history. Cement paste specimens with water-cement ratios of 0.7, 0.5 and 0.3 were subjected to monotonic, sustained or cyclic loading, while mortar specimens with a water-cement ratio of 0.5 were subjected to monotonic loading. One hundred and thirty ( 130) specimens were tested at ages ranging from 27 to 29 days, using a closed-loop servo-hydraulic testing machine. After loading, slices of material were removed for study at a magnification of 1 250x in a scanning electron microscope. Cracking on transverse and longitudinal surfaces was measured. Statistical and stereological models are developed to convert the surface crack distributions to three-dimensional distributions. A self-consistent model is developed tc estimate the elastic moduli of transversely isotropic cracked materials. These models are used to correlate submicrocracking with the reduction in stiffness and the shape of the stress-strain curve. The surface crack densities in cement paste and mortar are about ten times the density of bond and mortar microcracks in concrete at the same value of compressive strain. Submicrocracking accounts for a significant portion (20% to 90%) of the nonlinear respons of cement paste and mortar at all levels of applied compressive strain. As compressiVE strain increases, other mechanisms, such as large microcracks, macrocracks, and creep, play an increasingly greater role

Using Event-B to Verify the Kmelia Components and Their Assemblies

International audienceBuilding reliable software systems from components requires to verify the consistency of components and the correctness of component assemblies. In this work, we design a verification method to address the problem of verifying the consistency of components states and the correctness of assembly contracts, using pre-/post-conditions. The starting point is specifications written with the Kmelia component model: a Kmelia component type declares provided and required services which are used to link components in component assemblies. We generate Event-B models from Kmelia specifications in such a way that we can check the consistency and also the correctness of assembly at the Kmelia level, using Event-B provers. An illustrative example based on a stock management system is used to support the presentation

Scrap metals’ role in circular economy in Ghana, using Sunyani as a case study

Scrap metals can create jobs. It can also be reused and recycled as resource recovery measure in a circular economic model for Ghana. This case study therefore is a preliminary assessment of the quantity and economic value of scrap metals as essential part of resource recovery in the circular economic model. The findings of the study shows that scrap metal industry is growing in the Sunyani Municipality and similar trend is likely in other cities in Ghana as well. The most abundant of the metals found was aluminum while copper was most expensive. Though sales of the scrap was profitable, it was done on monthly basis owing to low rate of volume of scrap realized by the owners. Much of the scrap was dumped at various waste dumping sites in the municipality, thus raising concerns about lack of knowledge of residents about the profitability and recovery values of scrap metals in the circular models. As a result, this could lead to environmental pollution, inefficient resource utilization and energy uses. Therefore, proper education, policy and regulatory measures are key recommendations to prevent these and encourage uses of scrap metals in the circular economy of Ghana. Also, it is recommended that transfer, recycling and foundry stations should be built to prevent high transportation cost due to long haulage distance to final destination points of sales and recycling or reuses.Key words: Scrap metals, job creation, resource recovery, reuse, recycle, circular economy