A generic operational simulation for early design civil unmanned aerial vehicles

Contemporary aerospace programmes often suffer from large cost overruns, delivery delays and inferior product quality. This is caused in part by poor predictive quality of the early design phase processes with regards to the operational environment of a product. This paper develops the idea of a generic operational simulation that can help designers to rigorously analyse and test their early product concepts. The simulation focusses on civil Unmanned Air Vehicle products and missions to keep the scope of work tractable. The research agenda is introduced along with ideas, initial results and future work. Designers specify details about their product, its environment and anticipated operational procedures. The simulation returns information that can help to estimate the value of the product using the value-driven design approach. Information will include recurring and non-recurring mission cost items. The research aim is to show that an operational simulation can improve early design concepts, thereby reducing delays and cost overruns. Moreover, a trade-off between mission fidelity and model generality is sought along with a generic ontology of civil Unmanned Air Vehicle missions and guidelines about capturing operational informatio

Evaluation of the changes in working limits in an automobile assembly line using simulation

The aim of the work presented in this paper consists of the development of a decision-making support system, based on discrete-event simulation models, of an automobile assembly line which was implemented within an Arena simulation environment and focused at a very specific class of production lines with a four closed-loop network configuration. This layout system reflects one of the most common configurations of automobile assembly and preassembly lines formed by conveyors. The sum of the number of pallets on the intermediate buffers, remains constant, except for the fourth closed-loop, which depends on the four-door car ratio (x) implemented between the door disassembly and assembly stations of the car body. Some governing equations of the four closed-loops are not compatible with the capacities of several intermediate buffers for certain values of variable x. This incompatibility shows how the assembly line cannot operate in practice for x0,97 in a stationary regime, due to the starvation phenomenon or the failure of supply to the machines on the production line. We have evaluated the impact of the pallet numbers circulating on the first closed-loop on the performance of the production line, translated into the number of cars produced/hour, in order to improve the availability of the entire manufacturing system for any value of x. Until the present date, these facts have not been presented in specialized literature. © 2012 American Institute of Physics

Order planning decision support system for customer driven manufacturing

An important goal in schedule production orders through a manufacturing facility is to assure that thework is completed as close as possible to its due date. Work that is late creates downstream delays,while early completion can be detrimental if storage space is limited. Production planning andcontrol manufacturing is becoming more difficult as family products increase and quantity decreases.This paper presents an ongoing information system development that aims the production planningof special test tables equipment for automobile components manufacturers. The simulated basedinformation system will be used to support planning and schedule activities; to compare and analyzethe impact of planning rescheduling; to forecast the production completion date; to detect bottlenecksand to evaluate machines performance

A simulação na Indústria 4.0: principais conceitos e abordagens

Atualmente as empresas estão inseridas num mercado cada vez mais competitivo e global. Para fazer face a essa competitividade as empresas devem estar em constante desenvolvimento. Como tal, e com a necessidade de um processo produtivo cada vez mais integrado e automatizado, a indústria evoluiu para a Indústria 4.0. Ao longo deste trabalho descrevem-se os nove pilares da Indústria 4.0, realçando-se a importância da simulação e do seu importante papel no apoio à decisão. Apresentam-se os principais conceitos, os paradigmas tradicionais e emergentes e evidenciam-se algumas ferramentas de simulação (simuladores) que permitem operacionalizar os modelos.Nowadays, companies are inserted in an increasingly competitive and global market. To cope with that competitiveness, companies must be in a constant development. As such, and with the need for an increasingly and integrated productive process, the industry has evolved to industry 4.0. Throughout this work, are described the nine pillars of industry 4.0, highlighting the importance of the simulations and it’s important role in decision support. The main concepts, the traditional and emergents paradigms are presented, and some simulation tools (simulaters) that allow the operationalization of the models are evidenced.Mestrado em Engenharia e Gestão Industria

Development of a decision support system for decision-based part/fixture assignment and fixture flow control = Ukusungulwa kohlelo lokuxhaswa kwezinqumo mayelana nokwabiwa kwezingxenye ezakhiwayo kanye nokuhanjiswa kwazo.

Doctoral Degree. University of KwaZulu-Natal, Durban.ABSTRACT: An intense competition in a dynamic situation has increased the requirements that must be considered in the current manufacturing systems. Among those factors, fixtures are one of the major problematic components. The cost of fixture design and manufacture contributes to 10-20% of production costs. Manufacturing firms usually use traditional methods for part/fixture assignment works. These methods are highly resource consuming and cumbersome to enumerate the available fixtures and stabilise the number of fixtures required in a system. The aim of this study was to research and develop a Decision Support System (DSS), which was useful to perform a decision-based part/fixture assignment and fixture flow control during planned production periods. The DSS was designed to assist its users to reuse/adapt the retrieved fixtures or manufacture new fixtures depending upon the state of the retrieved fixtures and the similarities between the current and retrieved cases. This DSS combined Case-Based Reasoning (CBR), fuzzy set theory, the Analytic Hierarchy Process (AHP) and Discrete-Event Simulation (DES) techniques. The Artificial Intelligence (AI) component of the DSS immensely used a fuzzy CBR system combined with the fuzzy AHP and guiding rules from general domain knowledge. The fuzzy CBR was used to represent the uncertain and imprecise values of case attributes. The fuzzy AHP was applied to elicit domain knowledge from experts to prioritise case attributes. New part orders and training samples were represented as new and prior cases respectively using an Object-Oriented (OO) method for case retrieval and decision proposal. Popular fuzzy ranking and similarity measuring approaches were utilised in the case retrieval process. A DES model was implemented to analyse the performances of the proposed solutions by the fuzzy CBR subsystem. Three scenarios were generated by this subsystem as solution alternatives that were the proposed numbers of fixtures. The performances of these scenarios were evaluated using the DES model and the best alternative was identified. The novelty of this study employed the combination of fuzzy CBR and DES methods since such kinds of combinations have not been addressed yet. A numerical example was illustrated to present the soundness of the proposed methodological approach. Keywords: Decision support systems, case-based reasoning, analytic hierarchy process, fuzzy set theory, object-oriented methods, discrete-event simulation, fixtures. IQOQA LOCWANINGO : Ukuncintisana okunezinhlelo eziguquguqukayo kulesi sikhathi samanje sekwenze ukuthi kube nezidingo ezintsha ezinhlelweni zokukhiqiza. Phakathi kwakho konke lokhu izingxenye (fixtures) zingezinye zezinto ezidala izinkinga. Intengo yokwakha uhlaka lwengxenye kanye nokuyikhiqiza kubiza amaphesenti ayi-10 kuya kwangama-20 entengo yokukhiqiza. Amafemu akhiqizayo avamise ukusebenzisa izindlela ezindala zomsebenzi wokwaba izingxenye. Lezi zindlela zidla kakhulu izinsizangqangi futhi kuthatha isikhathi eside ukubala izingxenye ezikhona nokuqinisekisa ukuthi kunesibalo esanele kulokho okumele kube yikho ohlelweni lokusebenza. Inhloso yalolu cwaningo bekungukucwaninga nokusungula i-Decision Support System (DSS) ebe lusizo ekwenzeni umsebenzi wokuthatha izinqumo ngokwabiwa kwezingxenye kanye nokuhanjiswa kwazo ngezikhathi ezimiselwe ukukhiqiza. I-DSS yakhelwa ukusiza labo abayisebenzisayo ukuze basebenzise noma bazisebenzise lapho zingakaze zisetshenziswe khona lezo zingxenye ezibuyisiwe, noma kwakhiwe ezintsha kuya ngokuthi zibuyiswe zinjani lezi ezibuyisiwe nokuthi ziyafana yini nalezo ezintsha. I-DSS isebenzise amasu ahlanganise i-Case-Based Reasoning (CBR), injulalwazi echazwa ngokuthi i-fuzzy, ne-Analytic Hierarchy Process (AHP) ne-Discrete-Event Simulation (DES). I-Artificial Intelligence (AI) eyingxenye ye-DSS isebenzise kakhulu uhlelo lwe-fuzzy CBR luhlangene ne-fuzzy AHP kulandelwa imithetho yolwazi olumayelana nohlobo lomsebenzi. I-CBR isetshenziswe ukumelela lezo zimo zamanani ezingaqondakali nezingaphelele kulezo zingxenye. I-AHP e-fuzzy yasetshenziswa ukuze kutholakale ulwazi kochwepheshe olubeka phambili lezo zingxenye. Ama-oda ezingxenye ezintsha kanye namasampuli asetshenziselwa ukuqeqesha avezwe njengamasha kanye nabekade evele ekhona ngokulandelana kusetshenziswa indlela eyaziwa ngokuthi yi-Object-Oriented (OO) method lapho kubuyiswa izinto noma kunezinqumo eziphakanyiswayo. Izindlela ezijwayelekile zokulandelanisa nokufanisa zisetshenziswe ohlelweni lokubuyisa izinto. Kusetshenziswe isu eliyi-DES ukuhlaziya ukusebenza kwezisombululo eziphakanyiswe yindlela ye-CBR e-fuzzy. Le ndlela iphinde yaveza izimo ezintathu eziphakanyiswe ukuba zibe yisisombululo esibalweni sezingxenye ezihlongozwayo. Ukusebenza kwalezi zimo kuhlungwe ngokusebenzisa indlela ye-DES kwase kuvela inqubo engcono. Ukungajwayeleki kwalolu cwaningo kusebenzise ingxube yezindlela ze-fuzzy CBR ne-DES ngoba lolu hlobo lwengxube belungakaze lusetshenziswe. Kusetshenziswe isibonelo sezibalo ekwethuleni ukusebenza kwale nqubo yokusebenza ehlongozwayo

Development of a decision support system for decision-based part/fixture assignment and fixture flow control.

Doctoral Degree. University of KwaZulu-Natal, Durban.An intense competition in a dynamic situation has increased the requirements that must be considered in the current manufacturing systems. Among those factors, fixtures are one of the major problematic components. The cost of fixture design and manufacture contributes to 10-20% of production costs. Manufacturing firms usually use traditional methods for part/fixture assignment works. These methods are highly resource consuming and cumbersome to enumerate the available fixtures and stabilise the number of fixtures required in a system. The aim of this study was to research and develop a Decision Support System (DSS), which was useful to perform a decision-based part/fixture assignment and fixture flow control during planned production periods. The DSS was designed to assist its users to reuse/adapt the retrieved fixtures or manufacture new fixtures depending upon the state of the retrieved fixtures and the similarities between the current and retrieved cases. This DSS combined Case-Based Reasoning (CBR), fuzzy set theory, the Analytic Hierarchy Process (AHP) and Discrete-Event Simulation (DES) techniques. The Artificial Intelligence (AI) component of the DSS immensely used a fuzzy CBR system combined with the fuzzy AHP and guiding rules from general domain knowledge. The fuzzy CBR was used to represent the uncertain and imprecise values of case attributes. The fuzzy AHP was applied to elicit domain knowledge from experts to prioritise case attributes. New part orders and training samples were represented as new and prior cases respectively using an Object-Oriented (OO) method for case retrieval and decision proposal. Popular fuzzy ranking and similarity measuring approaches were utilised in the case retrieval process. A DES model was implemented to analyse the performances of the proposed solutions by the fuzzy CBR subsystem. Three scenarios were generated by this subsystem as solution alternatives that were the proposed numbers of fixtures. The performances of these scenarios were evaluated using the DES model and the best alternative was identified. The novelty of this study employed the combination of fuzzy CBR and DES methods since such kinds of combinations have not been addressed yet. A numerical example was illustrated to present the soundness of the proposed methodological approach.Please refer to the PDF for author's keywords

Melhoria de fluxos de trabalho num hospital através da aplicação de princípios Lean Thinking

Dissertação de mestrado em Engenharia IndustrialEsta dissertação apresenta um projeto realizado no contexto de uma dissertação do Mestrado em Engenharia Industrial e foi desenvolvida no Hospital Senhora da Oliveira Guimarães, tendo como foco a melhoria do fluxo de utentes nos balcões de atendimento (Consulta Externa e Internamento) aplicando princípios de Lean HealthCare, isto é, princípios de Lean Thinking, adaptados aos serviços de saúde, melhorando, assim, a satisfação de utentes e colaboradores. A metodologia utilizada para esta dissertação foi a Investigação-Ação, iniciando-se esta por um diagnóstico. Neste diagnóstico foram identificados diversos problemas que ocorreram nos serviços em estudo usando ferramentas como diagramas de Spaghetti, programa Arena para simulação e tabelas de classificação de desperdícios. Estes problemas estavam relacionados com sinalização insuficiente, tempos de espera e de processamento elevados, desorganização nos postos de trabalho, material eletrónico e informático, frequentemente, avariados, entre outros. Para que se conseguisse resolver estes problemas, foram apresentadas algumas propostas de melhoria, recorrendo à utilização de ferramentas Lean, como 5S e Gestão Visual e outras como planos de manutenção e a instalação de máquinas de senhas para se reduzir o tempo de atendimento aos utentes. Com a aplicação destas propostas pretendeu-se uma melhor gestão de tempo de trabalho para os colaboradores, filas de espera menores, redução de deslocações para utentes e colaboradores e inexistência de sobreposição de fluxos de trabalho. Em termos monetários, o conjunto de propostas apresentadas poderia permitir uma poupança de mais de 70000 € anuais.This thesis presents a project carried out in the context of a dissertation of the Master in Industrial Engineering and was developed at the Hospital Senhora da Oliveira Guimarães, focusing on improving the flow of users in service counters (External consultation and Internment) applying principles of Lean HealthCare, ie, principles of Lean Thinking, adapted to health services, thus improving the satisfaction of users and employees. The methodology used for this dissertation was Action-Research, starting with a diagnosis. In this diagnosis, several problems that occurred, in the services under study, were identified using tools such as Spaghetti diagrams, the Arena program for simulation and scrap classification tables. These problems were related to insufficient signaling, high waiting and processing times, clutter in the workstations, electronic and computer equipment, frequently broken, among others. In order to solve these problems, some proposals for improvement were made, using Lean tools such as 5S and Visual Management and others as maintenance plans and the installation of ticket machines to reduce the time of service to users. With the application of these proposals, it was intended a better management of working time for employees, shorter queues, reduction of commuting to users and employees and non-overlapping of workflows. In monetary terms, the set of proposals could allow a savings 70000 annual €

Aeronautical life-cycle mission modelling framework for conceptual design

This thesis introduces a novel framework for life cycle mission modelling during conceptual aeronautical design. The framework supports object-oriented mission definition using Geographical Information System technology. Design concepts are defined generically, enabling simulation of most aeronautical vessels and many non-aeronautical vehicles. Moreover, the framework enables modelling of entire vessel fleets, business competitors and dynamic operational changes throughout a vessel life cycle. Vessels consist of components deteriorating over time. Vessels carry payload that operates within the vessel environment.An agent-based simulation model implements most framework features. It is the first use of an agent-based simulation utilising a Geographical Information System during conceptual aeronautical design. Two case studies for unmanned aircraft design apply the simulation. The first case study explores how the simulation supports conceptual design phase decisions. It simulates four different unmanned aircraft concepts in a search-and-rescue scenario including lifeboats. The goal is to learn which design best improves life cycle search performance. It is shown how operational and geographical impacts influence design decision making by generating novel performance information. The second case study studies the simulation optimisation capability: an existing aircraft design is modified manually based on simulation outputs. First, increasing the fuel tank capacity has a negative effect on life cycle performance due to mission constraints. Therefore, mission definition becomes an optimisation parameter. Changing mission flight speeds during specific segments leads to an overall improved design

Uma abordagem híbrida para sistemas de apoio à decisão utilizando redes de petri e técnicas de simulação

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.O objetivo do trabalho é propor um Sistema de Apoio à Decisão (SAD), com abordagem híbrida, utilizando Simulação e Redes de Petri como técnicas de modelagem de processos de fabricação e um Sistema Especialista para auxiliar em sua utilização. O SAD proporciona uma interface amigável para o usuário que, a partir da seleção de parâmetros de entrada, obtém como resposta uma série de dados sobre o processo de fabricação, que auxiliam na avaliação de seu desempenho. Para validar a proposta do SAD, alguns cenários particulares ao modelo de uma empresa foram testados, com objetivo de elaborar um conjunto de propostas para aprimorar o desempenho do seu sistema produtivo, avaliar impactos de alterações de parâmetros do modelo e prover melhor compreensão do sistema como um todo para auxiliar no processo de tomada de decisão e documentação da planta produtiva. Algumas alterações significativas foram sugeridas a partir de resultados obtidos na avaliação destes cenários. O sistema mantém um histórico de dados com os parâmetros selecionados e com os resultados obtidos, para que não seja necessário repetir testes com cenários já executados e com objetivo de estabelecer um comparativo entre resultados alcançados. Simulação, que constitui o principal módulo do protótipo, mostrou-se uma ferramenta adequada para construir o modelo do processo e servir de apoio na resolução de questões típicas do tipo what-if. Redes de Petri foram eficientes para validar estruturalmente os cenários do modelo proposto no simulador. O SAD possibilita que gestores, sem conhecimento de técnicas de modelagem, possam manipular dados e interagir com o modelo desenvolvido. O protótipo desenvolvido é genérico para processos de fabricação, sendo sua utilização possível para qualquer planta industrial, desde que os parâmetros do modelo sejam ajustados, com auxílio da interface de entrada de dados do sistema. Os resultados alcançados na utilização do SAD mostraram-se adequados para o modelo da empresa considerada como case de validação do protótipo, pois várias considerações sobre o desempenho do processo foram possíveis através de sua utilização