Interpreting the Object Constraint Language

The Object Constraint Language (OCL), which forms part of the UML 1.1. set of modelling notations is a precise, textual language for expressing constraints that cannot be shown in the standard diagrammatic notation used in UML. A semantics for OCL lays the foundation for building CASE tools that support integrity checking of the whole UML models, not just the component expressed using OCL. This paper provides a semantics for OCL, at the same time providing a semantics for classes, associations, attributes and states

Component Composition in Business and System Modelling

Bespoke development of large business systems can be couched in terms of the composition of components, which are, put simply, chunks of development work. Design, mapping a specification to an implementation, can also be expressed in terms of components: a refinement comprising an abstract component, a concrete component and a mapping between them. Similarly, system extension is the composition of an existing component, the legacy system, with a new component, the extension. This paper overviews work being done on a UK EPSRC funded research project formulating and formalizing techniques for describing, composing and performing integrity checks on components. Although the paper focuses on the specification and development of information systems, the techniques are equally applicable to the modeling and re-engineering of businesses, where no computer system may be involved

Semantics through Pictures

A diagrammatic approach to the semantics of OO modelling notations is proposed. This is based on an innovative and expressive notation dubbed ''constraint diagrams'', which can be used to precisely characterise a range of sophisticated, static constraints on OO models. Other notations, such as those found in UML, can be viewed as projections of constraint diagrams. Work on using constraint diagrams at the core of a 3D modelling notation is also briefly described as a means of similarly providing the semantics of diagrams imposing constraints on dynamic behaviour

Semantics Through Pictures: towards a diagrammatic semantics for object-oriented modelling notations

An object-oriented (OO) model has a static component, the set of allowable snapshots or system states, and a dynamic component, the set of filmstrips or sequences of snapshots. Diagrammatic notations, such as those in UML, each places constraints on the static and/or dynamic models. A formal semantics of OO modeling notations can be constructed by providing a formal description of (i) sets of snapshots and filmstrips, (ii) constraints on those sets, and (iii) the derivation of those constraints from diagrammatic notations. In addition, since constraints are contributed by many diagrams for the same model, a way of doing this compositionally is desirable. One approach to the semantics is to use first-order logic for (i) and (ii), and theory inclusion with renaming, as in Larch, to characterize composition. A common approach to (iii) is to bootstrap: provide a semantics for a kernel of the notation and then use the kernel to give a semantics to the other notations. This only works if a kernel which is sufficiently expressive can be identified, and this is not the case for UML. However, we have developed a diagrammatic notation, dubbed constraint diagrams, which seems capable of expressing most if not all static and dynamic constraints, and it is proposed that this be used to give a diagrammatic semantics to OO models

Prototype d’une micropompe dédiée à l’injection des médicaments anti-épileptiques

RÉSUMÉ L’épilepsie est une des maladies du système nerveux central qui demeure sans solution efficace malgré les progrès technologiques impressionnants dans le domaine biomédical. En effet, environ 15% des patients souffrants de cette maladie sont réfractaires à tout médicament ou autre solution médicale. De nos jours, le traitement d’épilepsie, chez les patients réfractaires, consiste à stimuler électriquement la région du cerveau provoquant les foyers épileptiques. De plus, des travaux de recherche sont en cours pour examiner les résultats d’injection des médicaments ou de refroidissement de régions épileptiques. Nous proposons dans ce mémoire une solution basée sur une micropompe automatisée et miniaturisée permettant d’empêcher le foyer épileptique de se déclarer et se propager en injectant des débits précis des médicaments à l’endroit de détection du foyer juste au moment de sa naissance. La micropompe choisie est basée sur un mécanisme qui génère un champ magnétique à l’aide d’une microbobine intégrée. Cette micropompe sert à manipuler un diaphragme intégré pour déplacer les médicaments à injecter. La membrane de la micropompe en question est fabriquée par polydiméthylsiloxane (PDMS) qui vibre à une fréquence variant entre 85 et 175 Hz. La micropompe permet de livrer un débit de 2.9 ml/min et est activée par un circuit de détection de crises épileptiques. Quant à l’interface électronique, elle regroupe un microcontrôleur, quelques circuits logiques simples et un convertisseur numérique – analogique (CNA) qui servent à contrôler et commander le courant alimentant la microbobine faisant partie de la micropompe. Le déclenchement de la micropompe proposée a été validé, en partie, à l'aide d'enregistrements d’électroencéphalogrammes intracorticaux (icEEG) des patients atteints d'épilepsies. Les résultats obtenus ont confirmé l’opération de l’injection précise des médicaments. Notre système, destiné à être implantable, se caractérise également par la réduction de la consommation d’énergie dans sa mise en oeuvre. Nous avons réalisé à ce sujet des circuits donnant lieu à des bonnes performances en terme d’économie d’énergie, comparé à un autre type de micropompes piézoélectriques du commerce que nous avons examiné dans ce projet dont la consommation est de l’ordre de 70 mA au lieu de 40 mA obtenue dans la micropompe proposée.----------ABSTRACT Approximately 15% of patients with partial epilepsy are neither drug responsive nor good candidate for surgery. There has been growing interest in neuro-responsive intracerebral local treatment of seizures such as focal drug delivery, focal cooling, or electrical stimulation. The latter requires an effective seizure-detection system and an intracortical stimulator. In this project, we present an automated miniaturized micropump that provides precise drug flow rate in order to control epileptic seizure. The implantable responsive drug delivery system proposed by Polystim team was validated using intracortical Electroencephalogram (icEEG) recordings from patients with refractory epilepsy. In this project, the proposed micropump is based on electromagnetic mechanism that is generated through microcoil and deflects a diaphragm fabricated using a polydimethysiloxane (PDMS), by supplying precise amount of current using a digital-to-analog convertor (DAC). The device delivers simultaneous focal drug to suppress the seizure following its onset detection by a dedicated microelectronic interface. The PDMS based membrane is driven under a range of an actuating frequency between 85 and 175 Hz. It provides a flow rate of 2.9 ml/min when all the inputs of the DAC are high and the operation frequency is 143 Hz. The feedback controller and the micropump are activated for a given duration (2, 4, 8, 16 seconds) on response to seizure detections, but they remain in sleep mode for the rest of time. The experimental results demonstrated the detection accuracy of proposed implantable responsive drug delivery systems. The implemented control circuit provides a good performance in term of power consumption, comparing with another piezoelectric micropump we previously used in our experiments. The later requires about 70 mA instead of 40 mA for the proposed micropump

Visual Specification Patterns

Visual modelling notations such as constraint diagrams can be used for the behavioural specifications of software components. This includes specifying invariants on classes or types and preconditions and postconditions of operations. However, one current problem in specifying components comes from the fact that editing constraints manually is time consuming and error prone and so we may adopt a pattern-based approach to alleviate this problem. One way to simplify the definition of constraints is to identify and capture those recurring constraints in the form of visual specification patterns. Such patterns would facilitate the automatic generation of diagrammatic constraints. This paper identifies some specification patterns that frequently occur when specifying software components and provides a diagrammatic representation of these patterns. This will form the basis of a library of specification patterns that could be used in the context of tools. We also show how such patterns can be combined in order to specify more complex constraints