Regular Set of Representatives for Time-Constrained MSC Graphs

Systems involving both time and concurrency are notoriously difficult to analyze. Existing decidability results apply in settings where clocks on different processes cannot be compared or where the set of timed executions is regular. We prove new decidability results for timed concurrent systems, requiring neither restriction. We consider the formalism of time-constrained MSC graphs (TC-MSC graphs for short), and study whether the set of timed executions generated by a TC-MSC graph is empty or not. This emptiness problem is known to be undecidable in general. Our approach for obtaining decidability consists of two steps: (i) find a subset R of representative timed executions, that is, for which every timed execution of the system has an equivalent, up to commutation, timed execution in R, and (ii) prove that R is regular. This allows us to solve the emptiness problem under the assumption that the TC-MSC graph G is well-formed. In particular, a well-formed TC-MSC graph is prohibited from forcing any basic scenario to take an arbitrarily long time to complete. Secondly, it is forbidden from enforcing unboundedly many events to occur within a single unit of time. We argue that these restrictions are indeed practically sensible.Il est notoirement difficile d'analyser les comportements de systémes décrits par des modèles qui comportent à la fois du temps et de la concurrence. Des résultats de décidabilité existent pour des modèles dans lesquels les valeurs des horloges sur différents processus ne peuvent pas être comparées, ou lorsque les modèles ont des ensembles d'exécutions temporisés réguliers. Dans ce travail, nous montrons de nouveaux résultats de décidabilité pour des modèles temporisés et concurrents, qui ne s'appuient sur aucune de ces restrictions. Nous étudions le formalisme des time-constrained MSC graphs (TC-MSC graphs), initalement proposés, et le problème qui consiste à savoir si l'ensemble des exécutions temporisées d'un modèle est vide ou non. Ce problème a été prouvé indécidable en général pour les TC-MSC graphs. Notre approche pour obtenir une procédure de décision comporte deux étapes : (i) trouver un sous-ensemble R d'exécutions temporisées appelé ensemble des représentants : pour toute exécution temporisée du système, on doit pouvoir trouver une exécution équivalente dans R modulo commutation, (ii) prouver que R est régulier. L'existence d'un ensemble de représentants régulier permet de résoudre le problème de la vacuité de l'ensemble des exécutions d'un TC-MSC graph. Nous proposons une restriction aux TC-MSC graphs, que nous appelons TC-MSC Graph bien formés. Dans un TC-MSC graph bien formé, on ne peut forcer le système à exécuter un nombre arbitrairement grand d'événements en un laps de temps fini. Il est également interdit qu'un MSC prenne obligatoirement un temps arbitrairement long pour être entièrement exécuté. Les restrictions imposées aux TC-MSC graph bien formés réduisent peu la puissance d'expression du langage, et permettent de garantir l'existence d'un ensemble régulier de représentants

S-100 Overlays: A Brave New World?

Marine Information Overlay (MIO) is a generic term used to describe chart and navigation related information that supplement the content that is already contained in an ENC. This includes both static and dynamic information such as tide/water level, current flow, meteorological, oceanographic, and environmental protection. With the advent of S-100 and S-101, there is increased interest in providing a wide variety of ‘new’ overlay information. This paper provides a brief history of S-57 MIOs. Examples of navigational and non-navigation MIOs are given in terms of how currently used, by who, and for what purpose. Recommendations are provided for making a transition from S-57 MIOs to S-100 overlays that can be used with the ‘Next Generation’ ENC. More specifically, what has been proposed, how should they work, who will provide, and some future challenges/opportunities related to implementation

A case study of business intelligence applications for business users

This research is conducted in two parts, with the first part reviewing the standard industry approach to providing organisations with business intelligence (BI) architecture. The discussion begins with a brief history of the evolution of data warehouses and business intelligence (DW/BI) systems. The generic approach to developing a DW/BI is described and the interfaces and features of BI applications are explored as to how they support the various user roles within an organisation e.g. executive, business user and business analyst. The discussion is presented using references to the Zachman Framework. The second part of the research focuses on a case study examining an organisation's implementation of a bespoke BI solution which is supporting its business managers with decision support, reporting and analysis. Where today's business intelligence is about giving business users the tools to get the information they need out of the data warehouse and thus reducing the reliance on IT departments, the bespoke solution studied puts the reliance on IT staff to support their business intelligence requirements. The BI requirements are compared and contrasted against the features of third party BI tools to reach a conclusion as to whether they support the reporting needs of the planning group in the case study or whether their needs are so specific that a bespoke solution is the best option and thus reliance on IT departments is still necessary to support the delivery of business intelligence. The findings from the first part of the research are the view that for the successful development of BI applications the BI user's needs should be addressed from the requirements stage, and the development of BI applications should run as a parallel activity alongside the data warehouse development activities. The BI applications should be developed by BI developers who have knowledge of the business, rather than technical IT staff. This view is supported by leading DW/BI authors such Kimball et al. (2008). The research also found the needs of the BI application users can be analysed by grouping them into one of five classifications of user - Tourists, Farmers, Explorers, Miners and Operators and that different user interfaces are needed to support their needs. The case study in the second part of the research found that the implementation of the DW/BI system in SAP using SAP BEx software fails to provide planning staff with BI applications that meet with all their reporting and analysis needs and has therefore led to the development of bespoke applications. The findings suggest that this may be because the planning staff were not involved at the scoping and planning stage of developing the DW/BI. The investigations found that most of the features in the bespoke BI system could be developed using a third party solution and that they are available in the SAP family of products. The level of expertise needed to develop the features ranged from easy to technical. The adoption of a third party tool could be used to develop the reports by the BI application developers identified by Kimball et al. (2008) and provide the planning managers with an intuitive and flexible user interface that can be easily customised and maintained. It was also found that SAP BusinessObject's Crystal Reports provide a rich user interface that is easy to use to support most of the BI features

An Evaluation of the Sustainability of Global Tuna Stocks Relative to Marine Stewardship Council Criteria

The Marine Stewardship Council (MSC) has established a program whereby a fishery may be certified as being sustainable. The sustainability of a fishery is defined by MSC criteria which are embodied in three Principles: relating to the status of the stock, the ecosystem of which the stock is a member and the fishery management system. Since many of these MSC criteria are comparable for global tuna stocks, the MSC scoring system was used to evaluate nineteen stocks of tropical and temperate tunas throughout the world and to evaluate the management systems of the Regional Fishery Management Organizations (RFMO) associated with these stocks

The Tulczyjew triple for classical fields

The geometrical structure known as the Tulczyjew triple has proved to be very useful in describing mechanical systems, even those with singular Lagrangians or subject to constraints. Starting from basic concepts of variational calculus, we construct the Tulczyjew triple for first-order Field Theory. The important feature of our approach is that we do not postulate {\it ad hoc} the ingredients of the theory, but obtain them as unavoidable consequences of the variational calculus. This picture of Field Theory is covariant and complete, containing not only the Lagrangian formalism and Euler-Lagrange equations but also the phase space, the phase dynamics and the Hamiltonian formalism. Since the configuration space turns out to be an affine bundle, we have to use affine geometry, in particular the notion of the affine duality. In our formulation, the two maps $\alpha$ and $\beta$ which constitute the Tulczyjew triple are morphisms of double structures of affine-vector bundles. We discuss also the Legendre transformation, i.e. the transition between the Lagrangian and the Hamiltonian formulation of the first-order field theor