Documentação da lógica de modelos de simulação por meio do uso da técnica de modelagem IDEF-SIM.

A gestão do conhecimento aplicada em projetos de simulação é de grande importância, uma vez que ela possibilita a retenção do conhecimento, podendo este ser repassado para outras pessoas e até mesmo utilizado em projetos futuros. Dessa forma, é necessário registrar as lógicas de programação utilizadas em modelos computacionais. Assim, o objetivo desse trabalho é verificar a aplicabilidade da técnica de modelagem IDEF-SIM no registro de lógicas de programação de modelos de Simulação a Eventos Discretos. Essa aplicabilidade será analisada, incluindo, se for necessário, alterações na técnica para aperfeiçoá-la. Para isso, primeiramente foi realizada uma revisão sistemática da literatura com a finalidade de verificar como a técnica IDEF-SIM está sendo utilizada, identificando as principais lacunas. Também foram definindos os parâmetros para a pesquisa, como a técnica utilizada e os softwares para a construção dos modelos computacionais. Logo em seguida, através do método de pesquisa-ação, foram selecionados três modelos simulados no software ProModel®. A cada ciclo da pesquisa-ação, um modelo foi reproduzido, sendo cada um deles convertidos para o IDEF-SIM com as suas lógicas de programação e depois reproduzido no software FlexSim®. Os softwares ProModel® e FlexSim® foram escolhidos devido à diferença existente em relação à programação dos mesmos. O grau de dificuldade e inserção de elementos foram aumentando em cada ciclo da pesquisa-ação. As análises e conclusões de cada ciclo foram feitas por testes estatísticos, uma vez que os modelos foram programados por dois diferentes especialistas. Ao final de cada seção, melhorias propostas no IDEF-SIM foram identificadas para o próximo ciclo. Para a confirmação da pesquisa, um processo hipotético foi construído e aplicado em uma sala de aula, onde os alunos estavam aprendendo Simulação a Eventos Discretos. Após a programação, um questionário foi aplicado para medir a aplicabilidade da técnica. Depois dos testes, uma alteração no método de modelagem e simulação de Montevechi et al. (2010) foi proposta. Através dos ciclos de pesquisa-ação e do questionário respondido, pode-se afirmar que a técnica de fato consegue reproduzir a programação da lógica do modelo computacional, de forma clara e sem gerar confusões, contribuindo para a gestão do conhecimento em projetos de simulação

Adding Executable Context to Executable Architectures: Enabling an Executable Context Simulation Framework (ECSF)

A system that does not stand alone is represented by a complex entity of component combinations that interact with each other to execute a function. In today\u27s interconnected world, systems integrate with other systems - called a system-of-systems infrastructure: a network of interrelated systems that can often exhibit both predictable and unpredictable behavior. The current state-of-the-art evaluation process of these system-of-systems and their community of practitioners in the academic community are limited to static methods focused on defining who is doing what and where. However, to answer the questions of why and how a system operates within complex systems-of-systems interrelationships, a system\u27s architecture and context must be observed over time, its executable architecture, to discern effective predictable and unpredictable behavior. The objective of this research is to determine a method for evaluating a system\u27s executable architecture and assess the contribution and efficiency of the specified system before it is built. This research led to the development of concrete steps that synthesize the observance of the executable architecture, assessment recommendations provided by the North Atlantic Treaty Organization (NATO) Code of Best Practice for Command and Control (C2) Assessment, and the metrics for operational efficiency provided by the Military Missions and Means Framework. Based on the research herein, this synthesis is designed to evaluate and assess system-of-systems architectures in their operational context to provide quantitative results

Dynamic process modelling for business engineering and information systems evaluation

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This research is concerned with the pre-implementation evaluation of investments in Information Systems (IS). IS evaluation is important as organisations need to assess the financial justifiability of business change proposals that include (but usually are not limited to) the introduction of IS applications. More specifically, this research addresses the problem of benefits assessment within IS evaluation. We contend that benefits assessment should not be performed at the level of the IS application, as most extant evaluation methods advocate. Instead, to study the dynamics and the interactions of the IS applications with their surrounding environment, we propose to adopt the business process as the analytic lens of evaluation and to assess the impacts of IS on organisational, rather than on technical, performance indicators. Drawing on these propositions, this research investigates the potential of dynamic process modelling (via discrete-event simulation) as a facilitator of IS evaluation. We argue that, in order to be effective evaluation tools, business process models should be able to explicitly incorporate the effects of IS introduction on business performance, an issue that is found to be under-researched in previous literature. The above findings serve as the central theme for the development of a design theory of IS evaluation by simulation. The theory provides prescriptive elements that refer both to the design products of the evaluation and the design process by which these products can come into reality. The theory draws on a set of kernel theories from the business engineering domain and proposes a set of meta-requirements that should be satisfied by business process models, a meta-design structure that meets these requirements, and a design method that provides guidance in applying the theoretical propositions in practice. The design theory is developed and empirically tested by means of two real-life case studies. The first study is used to complement the findings of a literature review and to drive the development of the design theory's components, while the second study is employed to validate and further enhance the theory's propositions. The research results support the arguments for simulation-assisted IS evaluation and demonstrate the contribution of the design theory to the field

Aplicação da simulação a eventos discretos em conjunto com a pesquisa-ação para um projeto de melhoria em uma empresa de base tecnológica.

O gerenciamento dos dados de entrada é considerado um fator de alta influência no sucesso de um projeto de simulação, uma vez que problemas com os dados de entrada são frequentemente as razões pelas quais um modelo não é validado. Entretanto, as fases de coleta e modelagem de dados de entrada demandam muito tempo para serem executadas. Nesse contexto, o objetivo acadêmico deste trabalho é analisar a influência de diferentes estratégias de modelagem de dados de entrada na validação operacional de um modelo de simulação a eventos discretos. Como objetivo prático a pesquisa vai desenvolver um modelo computacional que será utilizado como ferramenta de tomada de decisão para o planejamento semanal da empresa objeto de estudo. Também se destaca o objetivo específico de analisar a aplicabilidade das técnicas de modelagem de processos BPMN e IDEF-SIM, utilizadas em conjunto, em um projeto de simulação. Nesta pesquisa serão utilizados os métodos pesquisa-ação e modelagem e simulação de forma conjunta. O objeto de estudo é o setor de reparos de uma empresa de base tecnológica. Foram realizados 3 ciclos de pesquisa-ação, sendo que cada um dos ciclos tinha como objetivo a finalização de uma das etapas do projeto de simulação: concepção, implementação e análise. Nesta pesquisa concluiu-se que não existem diferenças significativas entre os modelos que foram simulados com os tempos das atividades nas diferentes formas de modelagem dos dados de entrada, uma vez que ambos os modelos foram validados com a situação real. Na etapa de concepção a utilização do BPMN foi mais vantajosa, uma vez que a técnica permite a visualização das relações entre setores. Já na etapa de implementação, a utilização do IDEF-SIM facilitou a tradução da situação modelada para o software de simulação. E na etapa de análise a utilização combinada das duas técnicas tornou mais assertiva a proposição de cenários. A utilização da pesquisa-ação combinada com a modelagem e simulação favoreceu o desempenho do projeto

Development of a Process Modelling System for Simulation

This thesis details the development of a process modelling technique to aid a simulation model developer during the requirements gathering and conceptual modelling phases of a simulation project. There are a number of process modelling techniques available that are capable of being used during such phases of a simulation project, however there is currently a lack of process modelling techniques developed specifically to aid a simulation model developer in capturing, representing and communicating information and systems issues to persons involved in the operation of discrete systems under investigation. A detailed review of the literature related to techniques capable of supporting the pre-simulation phases of a simulation project is presented. The main conclusion of this review is that there is a specific lack of support available to aid a simulation model developer in the pre-coding phases of a simulation project. Currently there are no process modelling techniques available that specifically support the pre-simulation phases of a discrete event simulation project. To attempt to overcome this shortfall the thesis discusses the development of a process modelling technique specifically developed to support the pre-simulation phases of a simulation project. Objectives in the development of this technique were to develop a technique that: 1. Is capable of capturing a detailed description of a Discrete Event System; 2. Has a low modelling burden and therefore is capable of being used by non specialists; 3. Presents modelling information at a high semantic level so that manufacturing personnel can rationalise with it; 4. Has good visualisation capabilities. The technique developed is called Simulation Activity Diagrams (SADs). To demonstrate the ability of the SAD technique to model discrete event information a prototype process modelling tool, Process Modelling for Simulation (PMS) was developed. An evaluation of the SAD technique is then presented through of a number of real and conceptual discrete event systems used to examine the techniques ability to accurately model information along with its ease of use and modelling accuracy. The thesis concludes that more research is required in validating and developing SADs and in developing other techniques in the pre-simulation area

Applications integration for manufacturing control systems with particular reference to software interoperability issues

The introduction and adoption of contemporary computer aided manufacturing control systems (MCS) can help rationalise and improve the productivity of manufacturing related activities. Such activities include product design, process planning and production management with CAD, CAPP and CAPM. However, they tend to be domain specific and would generally have been designed as stand-alone systems where there is a serious lack of consideration for integration requirements with other manufacturing activities outside the area of immediate concern. As a result, "islands of computerisation" exist which exhibit deficiencies and constraints that inhibit or complicate subsequent interoperation among typical MCS components. As a result of these interoperability constraints, contemporary forms of MCS typically yield sub-optimal benefits and do not promote synergy on an enterprise-wide basis. The move towards more integrated manufacturing systems, which requires advances in software interoperability, is becoming a strategic issue. Here the primary aim is to realise greater functional synergy between software components which span engineering, production and management activities and systems. Hence information of global interest needs to be shared across conventional functional boundaries between enterprise functions. The main thrust of this research study is to derive a new generation of MCS in which software components can "functionally interact" and share common information through accessing distributed data repositories in an efficient, highly flexible and standardised manner. It addresses problems of information fragmentation and the lack of formalism, as well as issues relating to flexibly structuring interactions between threads of functionality embedded within the various components. The emphasis is on the: • definition of generic information models which underpin the sharing of common data among production planning, product design, finite capacity scheduling and cell control systems. • development of an effective framework to manage functional interaction between MCS components, thereby coordinating their combined activities. • "soft" or flexible integration of the MCS activities over an integrating infrastructure in order to (i) help simplify typical integration problems found when using contemporary interconnection methods for applications integration; and (ii) enable their reconfiguration and incremental development. In order to facilitate adaptability in response to changing needs, these systems must also be engineered to enable reconfigurability over their life cycle. Thus within the scope of this research study a new methodology and software toolset have been developed to formally structure and support implementation, run-time and change processes. The tool set combines the use of IDEFO (for activity based or functional modelling), IDEFIX (for entity-attribute relationship modelling), and EXPRESS (for information modelling). This research includes a pragmatic but effective means of dealing with legacyl software, which often may be a vital source of readily available information which supports the operation of the manufacturing enterprise. The pragmatism and medium term relevance of the research study has promoted particular interest and collaboration from software manufacturers and industrial practitioners. Proof of concept studies have been carried out to implement and evaluate the developed mechanisms and software toolset

Modelling large scale enterprises : A distributed simulation approach.

Distributed simulation provides an alternative solution when today's highly complicated systems including manufacturing are to be simulated. Complexities involved in implementation, the need for more expertise, high development cost and long implementation time etc. along with a lack of guidelines for developing distributed simulation, and the complexity of tools and techniques used to implement schemes, resulted in the lack of acceptance for distributed simulation among the general simulation community. In order to address some of these issues, a new approach is proposed for modelling and simulating large scale enterprises using distributed simulation. The proposed approach which includes a comprehensive methodology for distributed enterprise simulation, developed by combining activities required for traditional sequential simulation with additional activities required for distributed simulation. The thesis elaborates the additional activities required for distributed simulation in different chapters with simplified approaches for carrying out these activities. These include an approach to decide the appropriate simulation strategy (SimSS process), a simplified approach to modelling and model partitioning, a synchronization mechanism that approximately synchronizes the distributed enterprise simulation and an approach for developing distributed simulation using tools and technologies which are popular, well accepted and also cost effective. The differences between the traditional distributed simulation approaches and the proposed methodology include: partitioning of the conceptual model into logical processes before transforming them into computer simulation models, use of commercial simulation software to implement the distributed simulation, and use of cost effective and popular middleware and programming languages. Illustration of the proposed approaches focuses on distributed manufacturing applications

Integrated knowledge-based hierarchical modelling of manufacturing organizations

The objective of this thesis is to research into an integrated knowledge-based simulation method, which combines the capability of knowledge based simulation and a structured analysis method, for the design and analysis of complex and hierarchical manufacturing organizations. This means manufacturing organizations analysed according to this methodology can manage the tactical and operational planning as well as the direct operation of shop floor. [Continues.

Understanding the effects of e-business on business processes, a simulation approach

This thesis defines a new approach to the analysis of the effect of e-business on business processes, utilising simulation as evaluation tool. This research was focused on answering five research questions about the suitability of simulation in this context, the role of static modelling and generic business processes, the identification of patterns for e-business activities and how to operationalise these patterns into components in simulation software, as well as how to use these components. Requirements for modelling of e-business processes were identified and documented. Pilot cases studies proved the potential of simulation for studying e-business processes (Feasibility). Generic e-business activities were derived and classified from the literature and case studies in order to fill gaps identified in existent process models. Re-usable simulation components are proposed as a result of the unique combination of simulation and e-activities in order to make simulation modelling of e-business easier. The components were tested in industrial case studies and quasi-experiments with end users for feasibility, usability and usefulness. Results show that the components' approach is feasible, that having re-usable components promotes a better analysis, (usefulness) and that it is easy to build models using the components (usability). The theoretical novelty of this research resides in bringing together three areas of study: ebusiness, simulation and business processes to analyse e-business implementations. The research contributes to the knowledge of components and re-use theory in simulation by proposing a new approach to component development, operationalisation and analysis of the degree of granularity required for these components. From a practical point of view, this research provides companies with an easier and more complete way of analysing e-business processes, breaking the barrier for the use of simulation, speeding up model building of eprocesses and getting a better understanding of the dynamics of e-processes. Future work in the area will include extending the component approach to supply chains and inter-company transactions.This thesis defines a new approach to the analysis of the effect of e-business on business processes, utilising simulation as evaluation tool. This research was focused on answering five research questions about the suitability of simulation in this context, the role of static modelling and generic business processes, the identification of patterns for e-business activities and how to operationalise these patterns into components in simulation software, as well as how to use these components. Requirements for modelling of e-business processes were identified and documented. Pilot cases studies proved the potential of simulation for studying e-business processes (Feasibility). Generic e-business activities were derived and classified from the literature and case studies in order to fill gaps identified in existent process models. Re-usable simulation components are proposed as a result of the unique combination of simulation and e-activities in order to make simulation modelling of e-business easier. The components were tested in industrial case studies and quasi-experiments with end users for feasibility, usability and usefulness. Results show that the components' approach is feasible, that having re-usable components promotes a better analysis, (usefulness) and that it is easy to build models using the components (usability). The theoretical novelty of this research resides in bringing together three areas of study: ebusiness, simulation and business processes to analyse e-business implementations. The research contributes to the knowledge of components and re-use theory in simulation by proposing a new approach to component development, operationalisation and analysis of the degree of granularity required for these components. From a practical point of view, this research provides companies with an easier and more complete way of analysing e-business processes, breaking the barrier for the use of simulation, speeding up model building of eprocesses and getting a better understanding of the dynamics of e-processes. Future work in the area will include extending the component approach to supply chains and inter-company transactions

Development of VR-simulator software for manufacturing systems as a decision making and simulation tool

Modern manufacturing is characterised by high levels of automation and integration, complex interactions among system elements, and high capital costs. Simulation and Virtual Reality technologies hold tremendous promise for reducing costs, improving quality, process data management, enhancing control over operations and shortening the time-to-market for manufactured goods. Unfortunately, these technologies still remains largely underutilised by industry today due to the requirement for a high standard of skills in programming and modelling methodologies. Visualisation has become a critical component of simulation technology in manufacturing applications. It provides the simulation practitioners with an environment to discuss and get a better understanding of the simulation model’s behaviour. Graphical presentation and animation can be a significant tool to communicate the outcome of simulation models for the non-technical audience. Decision makers often do not have the technical knowledge to understand the statistical results of a simulation model. But when the outcome can be expressed using animation, a better level of understanding becomes possible. This thesis presents a VR-Simulator software developed entirely by the author to overcome some of the limitations of simulation packages to allow users (who are not specialists in simulation and virtual reality techniques, or have no programming skills) to develop simulation and virtual models of manufacturing systems automatically without any need for excessive training on modelling techniques or programming. The users can interact with the generated models using voice commands and virtual reality devices (e.g. HMD). The VR-Simulator can be used as an operational décision-support tool to enable decision makers to model and analyse manufacturing systems