Free energy techniques provide the basis for an analysis of aspects of the liquid-vapour interface undertaken in this study. The main focus of this work is an extensive theoretical investigation into properties of the surface tension, including curvature dependence and supersaturation effects, using Monte Carlo computer simulation techniques.

The Unified Modelling Language (UML) is intended to express complex ideas in an intuitive and easily understood way. It is important because it is widely used in software engineering and other disciplines. Although an official definition document exists, there is much debate over the precise meaning of UML models. ¶ In response, the academic community have put forward many different proposals for formalising UML, but it is not at all obvious how to decide between them. Indeed, given that UML practitioners are inclined to reject formalisms as non-intuitive, it is not even obvious that the definition should be “formal” at all. Rather than searching for yet another formalisation of UML, our main aim is to determine what would constitute a good definition of UML. ¶ The first chapter sets the UML definition problem in a broad context, relating it to work in logic and the philosophy of science. More specific conclusions about the nature of model driven development are reached in the beginning of Chapter 2. We then develop criteria for a definition of UML. Applying these criteria to the existing definition, we find that it is lacking in clarity. We then set out to test the precision of the definition. The test is to take an apparently inconsistent model, and determine whether it really is inconsistent according to the definition. ¶ Many people have proposed that UML models are graphs, but few have justified this choice using the official definition of UML. We begin Chapter 3 by arguing from the official definition that UML models are graphs and that instantiation is a graph homomorphism into an interpretation functor. The official definition of UML defines the semantics against its abstract syntax, which is in turn defined by a UML model. Chapters 3 and 4 prepare for our test by resolving this apparent circularity. The result is a semantics for the metamodel fragment of the language. ¶ In Chapter 5, we find, contrary to popular belief, that the official definition does provide sufficient semantics to classify the example model as inconsistent. Moreover, the sustained study of the semantics in Chapters 3 to 5 confirms our initial argument that the semantic domain is graphs. The Actions are the building blocks of UML’s prescriptive dynamics. We see that they can be naturally defined as graph transformation rules. Sequence diagrams are the main example of descriptive dynamics, but we find that their official semantics are broken. The “recorded history” approach should be replaced, we suggest, by a graph-oriented dynamic logic. ¶ Chapter 6 presents our early work on dynamic logic for UML sequence diagrams and further explores the proposed semantic repairs. In Chapter 7, guided by the criteria developed in Chapter 2, we critically survey the UML formalisation literature and conclude that an existing body of graph transformation based work known as “dynamic metamodelling” is very close to what is required. ¶ The final chapter draws together our conclusions. It proposes a category theoretic construction to merge models of the syntax and semantic domain, yielding a type graph for the graph transformation system which defines the dynamic semantics of the language. Finally, it outlines the further work required to realise a satisfactory definition of UML.

Identifying the detrimental effect of environmental factors and subsystem interactions are one of themost challenging aspects of early hazard assessment in the design of complex safety critical systems.Therefore, a complete understanding of potential failure effects before the catastrophe happens is a verydifficult task. The thesis proposes a model-based hazard analysis procedure for early identification ofpotential safety issues caused by unexpected environmental factors and subsystem interactions within acomplex safety critical system. The proposed methodology maps hazard and vulnerability modes tospecific components in the system and analyzes the hazard propagation paths for risk control andprotection strategies. The main advantage of the proposed method is the ability to provide the designerswith means to use low-fidelity, high level models to identify hazardous interactions. Using thistechnique, designers can examine the collective impacts of environmental and subsystem risks onoverall system during early stages of design and develop a hazard mitigation strategy.

Free energy techniques provide the basis for an analysis of aspects of the liquid-vapour interface undertaken in this study. The main focus of this work is an extensive theoretical investigation into properties of the surface tension, including curvature dependence and supersaturation effects, using Monte Carlo computer simulation techniques.

Integration is one of the driving themes in database and applied computing research. Starting with the development of Federated Information Systems and passing over to Enterprise Application Integration, the integration of distributed systems receives a lot of attention with the development of Web services these days. Integration on an architecture independent level can be cast to the integration of autonomous object oriented systems which requires the integration of object structure and object behaviour. Past research has mainly addressed the structural aspects meaning the integration of class attributes and relations. This thesis is addressing the integration of object behaviour and proposes a structured, model-driven approach for the integration of business processes specifying software application behaviour. It consists of the identification of correspondences between business processes on different levels of abstraction and associates the correspondences with integration patterns that lead to a specific technical integration. One advantage of the approach is that correspondences and patterns are defined separately, which enhances the re-usability of patterns in different integration scenarios. Integration scenarios can be distinguished between horizontal and vertical integration, and within or across enterprise borders. Within an enterprise, horizontal integration consists of integrating systems on the same level of abstraction and vertical integration consists of integrating systems on different levels of abstractions, whereas across enterprise borders, horizontal integration consists of determining the most appropriate systems, from among a set of functionally equivalent ones, and vertical integration consists of defining an appropriate combination of systems to create a new one. So far, there exist no approach that attempts to support all integration scenarios within a framework. This thesis proposes an integration approach that is able to support all integration scenarios mentioned before. The approach is built on a meta-meta layer architecture and provides generic methods and techniques for the logical integration of object behaviour based on a domain independent framework. The thesis proposes two alternative outcomes of an integration. First one creates a new global behaviour that integrates local behaviour and can be supported by a service oriented architecture. Second alternative outcome are synchronisation points between business process, so-called inter-process dependencies, that can be supported by an event-driven architecture. The advantages and disadvantages of both are discussed in detail.

Conceptual Modelling (CM) has received little attention in the area of Modelling and Simulation (M&S) and more specifically in Discrete Event Simulation (DES). It is widely agreed that CM is least understood despite its importance. This is however, not the case in other fields of science and engineering (especially, computer science, systems engineering and software engineering). In Computer Science (CS) alone, CM has been extensively used for requirements specification and some well-established methods are in practice. The aim of the thesis is to propose a CM framework based on the principles of software engineering and CS. The development of the framework is adapted from a well-known software engineering method called Structured Analysis and Design Technique (SADT), hence it is called SADT CM. It is argued that by adapting approaches from CS, similar benefits can be achieved in terms of formality, understanding, communication and quality. A comprehensive cross-disciplinary review of CM in CS and M&S is undertaken, which highlights the dearth of standards within M&S CM when compared to CS. Three important sub-fields of CS are considered for this purpose namely, information systems, databases and software engineering. The review identifies two potential methods that could be adopted for developing a M&S CM framework. The first method called PREView was found unsuitable for M&S CM in DES domain. Hence, the thesis concentrates on developing the framework based on SADT. The SADT CM framework is evaluated on three-in depth test cases that investigate the feasibility of the approach. The study also contributes to the literature by conducting a usability test of the CM framework in an experimental setting. A comprehensive user-guide has also been developed as part of the research for users to follow the framework.

<p>Juglone is a 1,4-naphthoquinone (1,4-NQ) and the allelochemical responsible for the well-known toxic effects of black walnut (<i>Juglans nigra</i>)<i> </i>and other members of the Juglandaceae. Juglone affects a variety of weed species via a mode of action unlike any commercially available herbicides, and thus has the potential to be used as a new natural product-based herbicide. However, lack of knowledge about its metabolism precludes introducing juglone biosynthesis traits into resistant crops through biotechnology. Herein, we established that juglone is derived from the phylloquinone pathway at the level of the intermediate 1,4-dihydroxy-2-naphthoic acid (DHNA). Phylloquinone is a primary 1,4-NQ made by all plants for photosynthetic electron transport. Despite the fundamental importance of phylloquinone, there are still unanswered questions about the subcellular architecture of the phylloquinone pathway. In chapter 3, we show that <i>o</i>-succinylbenzoate CoA-ligase is localized to both chloroplasts and peroxisomes and that its activity is vital in both organelles. The required dual localization of CoA ligase activity is a theme common to other plant pathways with CoA metabolic steps occurring in peroxisomes and thus leads us to propose a revised model of the phylloquinone pathway. Lastly, given the potential of introducing juglone biosynthesis as part of novel weed management strategies, we investigated the circumstances, costs, and benefits of producing allelochemicals in crops using an evolutionary game theory model. Together, this work (i) shows that the phylloquinone pathway provides crops with the biosynthetic framework to produce juglone, (ii) sheds new light on the phylloquinone pathway architecture, and (iii) reveals the circumstances in which producing an allelochemical will be an evolutionarily stable strategy. We envision these results will assist biotechnological efforts to utilize juglone as a novel, natural product-based herbicide.</p>

The National Health Insurance Scheme (NHIS) in Ghana was introduced to alleviate the problem of citizens having to pay for healthcare at the point of delivery, given that many did not have the financial resources needed to do so, and as such were unable to adequately access healthcare services. The scheme is managed from the national headquarters in the capital Accra, through satellite offices located in districts right across the length and breadth of the country. It is the job of these offices to oversee the operations of the scheme within that particular district. Current literature however shows us that there is a digital divide that exists between the rural and urban areas of the country which has led to differences in the management of information within urban-based and rural-based districts. This thesis reviews the variables affecting the management of information within the scheme, and proposes an information management model to eliminate identified bottlenecks in the current information management model. The thesis begins by reviewing the theory of health insurance, information management and then finally the rural-urban digital divide. In addition to semi-structured interviews with key personnel within the scheme and observation, a survey questionnaire was also handed out to staff in nine different district schemes to obtain the raw data for this study. In identifying any issues with the current information management system, a comparative analysis was made between the current information management model and the real-world system in place to determine the changes needed to improve the current information management system in the NHIS. The changes discovered formed an input into developing the proposed information management system with the assistance of Natural Conceptual Modelling Language (NCML). The use of a mixed methodology in conducting the study, in addition to the employment of NCML was an innovation, and is the first of its kind in studying the NHIS in Ghana. This study is also the first to look at the differences in information management within the NHIS given the rural-urban digital divide.

Um dos grandes problemas relacionados a modelagem de workflow consiste na utilização de técnicas de modelagem conceitual especificas a cada sistema de workflow, não havendo, dessa forma, urn modelo aceito consensualmente. Esta situação, decorrência do ambiente competitivo neste mercado, leva a não inclusão de muitas características conceitualmente importantes relacionadas a modelagem nos técnicas geralmente utilizadas. Um importante aspecto a ser tratado nos modelos conceituais e a questão da modelagem formal do workflow e que constitui o terra central deste trabalho. Esta dissertação apresenta uma técnica de modelagem de workflow utilizando como modelo de dados referencial o TF-ORM (Temporal Functionality in Objects with Roles Model). Esta técnica desenvolve uma especificação rigorosa de workflow em um nível conceitual, formalizando com a utilização de um modelo técnico seu comportamento interno (cooperação e interação entre tarefas) e seu relacionamento para o ambiente (designação de tarefas de trabalho para executores). Neste modelo, construções são apresentadas para representar, de forma eficiente, a modularização e o paralelismo. Uma linguagem textual de definição de workflow e apresentada. Adicionalmente é apresentada a utilização de descrições formais do workflow para gerar o esquema de dados do workflow e o conjunto de regras para seu gerenciamento. Em adição, o paradigma de regras oferece um formalismo conveniente para expressar computações reativas influenciadas por eventos externos, gerados fora do WFMS (Workflow Manager System). Finalmente é realizada uma analise sobre algumas ferramentas comerciais, procurando validar a praticidade dos modelos conceituais desenvolvidos. Os principais conceitos envolvidos em workflow são descritos e classificados de forma a possibilitar, a validação tanto dos conceitos quanto da modelagem através de um estudo de caso e a utilização de um sistema comercial. / One of the greatest problems in workflow modelling is the use of specific conceptual modelling techniques associated to each workflow system; there is not a consensual accepted model. This situation, a consequence of the strong competitive environment in this market, leads to the non-inclusion of many important conceptual characteristics. This restriction is a consequence of the restricted modelling techniques closely related with implementation models. An important aspect to be considered, and the central subject of this work, is the formal workflow modelling. A modelling technique using the TF-ORM (Temporary Functionality in Objects with Rolls Model) data model is here presented. The modelling technique develops a rigorous specification of workflow at the conceptual level, formalising in one model its internal behaviour (the co-operation and interaction among tasks) and its relationship with the environment (the designation of tasks). In this model, constructions where developed to represent, in an efficient form, the modularity and the parallelism of the activities. A formal language for the workflow definition is presented. Additionally, the use of formal workflow description is used to generate the data flow and rules set for its management. In addition, the rules paradigm offers a convenient formalism to express reactive computations influenced by external events generated outside the Workflow Manager System. Finally a case study is accomplished using some commercial modelling tools, to validate the developed conceptual models practicality.

Knowledge is considered important for the survival and growth of an enterprise. Currently knowledge is stored in various places including the bottom drawers of employees. The human being is considered to be the most important knowledge provider. Over the years knowledge based systems (KBS) have been developed to capture and nurture the knowledge of domain experts. However, such systems were considered to be separate and different from the traditional information systems development. Many KBS development projects have failed. The main causes for such failures have been recognised as the difficulties associated with the process of knowledge elicitation, in particular the techniques and methods employed. On the other hand, the main emphasis of information systems development has been in the areas of data and information capture relating to transaction based systems. For knowledge to be effectively captured and nurtured it is necessary for knowledge to be part of the information systems development activity. This thesis reports on a process of investigation and analysis conducted into the areas of information, knowledge and the overlapping areas. This research advocates a hybrid approach, where knowledge and information capture to be considered as one in a unified environment. A meta-schema design based on Formal Object Role Modelling (FORM), independent of implementation details, is introduced for this purpose. This is considered to be a key contribution of this research activity. Both information and knowledge is expected to be captured through this approach. Meta data types are provided for the capture of business rules and they form part of the knowledge base of an organisation. The integration of knowledge with data and information is also described. XML is recognised by many as the preferred data interchange language and it is investigated for the purpose of rule interchange. This approach is expected to enable organisations to interchange business rules and their meta-data, in addition to data and their schema. During interchange rules can be interpreted and applied by receiving systems, thus providing a basis for intelligent behaviour. With the emergence of new technologies such as the Internet the modelling of an enterprise as a series of business processes has gained prominence. Enterprises are moving towards integration, establishing well-described business processes within and across enterprises, to include their customers and suppliers. The purpose is to derive a common set of objectives and benefit from potential economic efficiencies. The suggested meta-schema design can be used in the early phases of requirements elicitation to specify, communicate, comprehend and refine various artefacts. This is expected to encourage domain experts and knowledge analysts work towards describing each business process and their interactions. Existing business processes can be documented and business efficiencies can be achieved through a process of refinement. The meta-schema design allows for a ?systems view? and sharing of such views, thus enabling domain experts to focus on their area of specialisation whilst having an understanding of other business areas and their facts. The design also allows for synchronisation of mental models of experts and the knowledge analyst. This has been a major issue with KBS development and one of the main reasons for the failure of such projects. The intention of this research is to provide a facility to overcome this issue. The natural language based FORM encourages verbalisation of the domain, hence increasing the understanding and comprehension of available business facts.