Despite nearly 50 years of attempts at reform, the US defense acquisition system continues to deliver weapon systems over budget, behind schedule, and with performance shortfalls. Why has acquisition reform failed? Three potential contributors were identified in the literature: the misalignment of incentives, a lack of a systems view, and a lack of objective evaluation criteria. This thesis considers these problems in the context of the most recent effort to transform the defense acquisition enterprise, evolutionary acquisition. First, game theory was employed to analyze the incentives of participants in the defense acquisition enterprise regarding the use of immature technology. It was found that there is a tragedy of the commons at work where acquisition programs serve as a common resource for stakeholders to meet their goals. The result is that participants are incentivized to use immature technology in contradiction of evolutionary acquisition policies. Second, the cost and performance of evolutionary acquisition in the context of the defense acquisition system was analyzed using a discrete event simulation. What was found was that evolutionary acquisition may lead to better performance from fielded systems and lower cost programs but also that the cost of operating the acquisition system as whole may actually rise. Finally, a method using price indices was developed to translate the gain in buying power resulting from improvements to the defense acquisition system into a monetary valuation. This allows for the application of options analysis to determine whether or not it is cost effective to pursue a potential improvement. A comparison with a more traditional approach revealed that simply using the NPV of cost savings may significantly understate value.

The factored state representation and concurrency semantics of Petri nets are closely related to those of classical planning models, yet automated planning and Petri net analysis have developed independently, with minimal and mainly unconvincing attempts at crossfertilisation. This thesis exploits the relationship between the formal reachability problem, and the automated planning problem, via Petri net unfolding, which is an attractive reachability analysis method for highly concurrent systems as it facilitates reasoning about independent sub-problems. The first contribution of this thesis is the theory of directed unfolding: controlling the unfolding process with informative strategies, for the purpose of optimality and increased efficiency. The second contribution is the application of directed unfolding to automated planning. Inspired by well-known planning heuristics, this thesis shows how problem specific information can be employed to guide unfolding, in response to the formal problem of developing efficient, directed reachability analysis methods for concurrent systems. Complimenting this theoretical work, this thesis presents a new forward search method for partial order planning which can be exponentially more efficient than state space search. Our suite of planners based on directed unfolding can perform optimal and suboptimal classical planning subject to arbitrary action costs, optimal temporal planning with respect to arbitrary action durations, and address probabilistic planning via replanning for the most likely path. Empirical results reveal directed unfolding is competitive with current state of the art automated planning systems, and can solve Petri net reachability problems beyond the reach of the original “blind” unfolding technique. / Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2008

As systems become more interconnected, the focus of engineering design must shift to include consideration for systems of systems (SoS) e ects. As the focus shifts from singular systems to systems of systems, so too must the focus shift from performance based analysis to an evaluation method that accounts for the tendency of such large scale systems to far outlive their original operational environments and continually evolve in order to adapt to the changes. It is nearly impossible to predict the nature of these changes, therefore the rst focus of this thesis is the measurement of the exibility of the SoS and its ability to evolve and adapt. Flexibility is measured using a combination of network theory and a discrete event simulation, therefore, the second focus is the development of a simulation environment that can also measure the system's performance for baseline comparisons. The results indicate that simulated exibility is related to the performance and cost of the SoS and is worth measuring during the design process. The third focus of this thesis is to reduce the computational costs of SoS design evaluation by developing heuristics for exibility. This was done by developing a network model to correspond with the discrete event simulation and evaluating network properties using graph theory. It was shown that the network properties can correlate with simulated exibility. In such cases it was shown that the heuristics could be used in connection with an evolutionary algorithm to rapidly search the design space for good solutions. The entire methodology was demonstrated on a multi-platform maintenance planning problem in connection with the Navy Hardware Open System Technologies initiative.

The most costly and labor-intensive activity for almost every warehouse is the order picking process and a key challenge for manufacturing companies is to store parts in an efficient way. Therefore, to minimize the order retrieval time when picking from a storage, the need of a sufficient storage categorization strategy becomes vital. One of the logistics centers at Scania in Södertälje stores parts that will be transported to the chassis assembly and the assembly of gearboxes and axles when needed in the production. In one of the storage areas at the logistics center, namely the PS storage, the forklift drivers picking from the storage have experienced congestion in the storage aisles and that it might be possible to reduce the order fulfillment time when picking the orders. This master thesis aims to investigate the possibility of optimizing the picking process in the PS storage, with respect to the order fulfillment time for the forklift drivers, with categorization of the goods. This has been analyzed with a heuristic optimization approach and with the use of a discrete event simulation model, where different categorization strategies have been applied on the storage and compared to the current state. By categorizing the goods in the PS storage, a reduction of the order fulfillment time can be done of around 4% - 5% compared to the current state with all tested categorization strategies. The strategy which has been shown to give the largest improvement is by categorizing the parts in the storage according to their final delivery address at the production line, which would reduce the order fulfillment time by 5.03% compared to the current state. With this categorization method, parts that are picked on the same route are located close to each other.

Les technologies RFID présentent des avantages non négligeables en comparaison aux technologies d'identification actuelles. Cependant, l'intégration de ces technologies dans les chaînes logistiques implique souvent des coûts élevés. Ainsi, les entreprises doivent conduire des analyses poussées pour évaluer l'impact des RFID sur le fonctionnement et l'économie des chaînes logistiques et décider de l'intégration ou non de ces technologies.Dans cette thèse nous nous concentrons sur la modélisation et l'analyse de l'introduction des technologies RFID dans les chaînes logistiques. Nous présentons d'abord une information générale sur les technologies RFID. Nous analysons ensuite la littérature sur l'intégration des RFID dans les chaînes logistiques en focalisant sur les défis et les avantages liés à l'intégration de ces technologies. Nous développons deux approches (analytique et par simulation) afin d'évaluer les impacts qualitatifs et quantitatifs des technologies RFID sur le fonctionnement et le profit des chaînes logistiques. Nous développons aussi une analyse du retour sur investissement (ROI), pour comparer les revenus obtenus à l'aide des technologies RFID avec les coûts associés à leur intégration. D'autre part, nous nous intéressons à l'amélioration des avantages de RFID dans les chaînes logistiques. Nous comparons les impacts de l'intégration de différentes RFID dans les chaînes logistiques par un remplacement simple des technologies d'identification actuelles et par la réorganisation des chaînes logistiques utilisant les nouvelles possibilités des technologies RFID. Les résultats obtenus dans ce travail mettent en évidence des perspectives intéressantes pour des études futures. L'originalité de cette étude est que nous comparons les impacts de plusieurs technologies RFID en les intégrant aux systèmes actuels et en reconstruisant des chaînes logistique grâce aux possibilités offertes par des technologies RFID. Notre modèle de simulation à événements discrets peut être utilisé comme un outil d'aide à la décision pour les sociétés qui visent à intégrer des technologies RFID.L'originalité de cette étude est que nous comparons les impacts de plusieurs technologies RFID en les intégrant aux systèmes actuels et en reconstruisant des chaînes logistique par les possibilités offertes par des technologies RFID. Notre simulation peut être utilisée comme un outil d'aide à la décision pour les sociétés qui considèrent l'intégration de technologies RFID. / In the last few years, RFID technologies have drawn considerable interests as one of the possible solutions to overcome these supply chain problems. However, integrating these technologies in supply chains induces large costs. Thus, companies must evaluate the impacts of RFID technologies on supply chain performances and economics, in order to decide whether these technologies should be integrated or not.In this thesis we focus on modeling and analyzing the impacts of introducing RFID technologies in supply chain. We first provided a basic knowledge of RFID technologies that includes the working process, the challenges and the obstacles of applying RFID technologies in supply chains. We then reviewed the literature and discussed the challenges and benefits related to integrating RFID in supply chains. Finally, we developed analytical and simulation approaches to evaluate qualitative and quantitative impacts of RFID technologies on supply chain performances and profits. We also developed ROI (Return On Investment) analysis, to compare the benefits obtained by RFID technologies with the costs associated to the integration of these technologies. Furthermore, we focused on how the benefits of RFID technologies can be improved by re-engineering supply chains using the characteristics of RFID technologies. Results obtained in this thesis highlight interesting perspectives for future studies. The main originality of this study is to compare the impacts of integrating different RFID technologies to supply chains by just replacing current identification technologies and by re-engineering supply chains using the new possibilities provided by RFID technologies. Our simulation can also be used as a decision support tool by companies that integrate RFID technologies.

abstract: The adoption of the Service Oriented Architecture (SOA) as the foundation for developing a new generation of software systems - known as Service Based Software Systems (SBS), poses new challenges in system design. While simulation as a methodology serves a principal role in design, there is a growing recognition that simulation of SBS requires modeling capabilities beyond those that are developed for the traditional distributed software systems. In particular, while different component-based modeling approaches may lend themselves to simulating the logical process flows in Service Oriented Computing (SOC) systems, they are inadequate in terms of supporting SOA-compliant modeling. Furthermore, composite services must satisfy multiple QoS attributes under constrained service reconfigurations and hardware resources. A key desired capability, therefore, is to model and simulate not only the services consistent with SOA concepts and principles, but also the hardware and network components on which services must execute on. In this dissertation, SOC-DEVS - a novel co-design modeling methodology that enables simulation of software and hardware aspects of SBS for early architectural design evaluation is developed. A set of abstractions representing important service characteristics and service relationships are modeled. The proposed software/hardware co-design simulation capability is introduced into the DEVS-Suite simulator. Exemplar simulation models of a communication intensive Voice Communication System and a computation intensive Encryption System are developed and then validated using data from an existing real system. The applicability of the SOC-DEVS methodology is demonstrated in a simulation testbed aimed at facilitating the design & development of SBS. Furthermore, the simulation testbed is extended by integrating an existing prototype monitoring and adaptation system with the simulator to support basic experimentation towards design & development of Adaptive SBS. / Dissertation/Thesis / Ph.D. Computer Science 2011

In today’s world, simulation and optimization are playing a vital role in reducing the time, cost and preserving resources. In manufacturing industries, there are ample amount of problems that go on with the expansion of the industry. In such cases, to tackle these problems simulation can be helpful to check whether any change in the current situation makes any effect on the current efficiency of the overall plant. In the presented case study, a solution to the problem of internal and external logistics has been designed by using simulation and optimization to improve part of a material flow of an organization. Basically, the organization whose major production is established in the south of Sweden deals with the manufacturing and assembly of equipment. Before the dispatch, all of them go to the painting section which is the expansion of the present shop floor. However, the design and analysis of the material handling system to feed the new painting line which is going to be established by the organization is the aim of this case study. While achieving this aim the literature regarding the discrete event simulation, Lean and Simulation-Based optimization related to the material handling system has been done. Furthermore, the appropriate material handling systems along with the different scenarios were suggested to reduce the cost and the lead times between the production line and the new painting line. To support this process a methodology combining simulation, optimization and lean production has been implemented under the framework of the design and creation research strategy. In the Kaizen workshop organized at a company with managers and stakeholders, the designed scenarios were presented and after some discussion one of them was chosen and the selected scenario was designed and optimized. Moreover, the Simulation-Based multi-objective optimization has been helpful for the optimization of the designed model proposed as a final solution.

Au CERN (Organisation européenne pour la recherche nucléaire), le contrôle et la supervision du plus grand accélérateur du monde, le LHC (Large Hadron Collider), sont basés sur des solutions industrielles (SCADA). Le LHC est composé de sous-systèmes disposant d’un grand nombre de capteurs et d’actionneurs qui rendent la surveillance de ces équipements un véritable défi pour les opérateurs. Même avec les solutions SCADA actuelles, l’occurrence d’un défaut déclenche de véritables avalanches d’alarmes, rendant le diagnostic de ces systèmes très difficile. Cette thèse propose une méthodologie d’aide au diagnostic à partir de données historiques du système. Les signatures des défauts déjà rencontrés et représentés par les listes d’alarmes qu’ils ont déclenchés sont comparées à la liste d’alarmes du défaut à diagnostiquer. Deux approches sont considérées. Dans la première, l’ordre d’apparition des alarmes n’est pas pris en compte et les listes d’alarmes sont représentées par un vecteur binaire. La comparaison se fait à l’aide d’une distance pondérée. Le poids de chaque alarme est évalué en fonction de son aptitude à caractériser chaque défaut. La seconde approche prend en compte l’ordre d’apparition des alarmes, les listes d’alarmes sont alors représentées sous forme de séquences symboliques. La comparaison entre ces deux séquences se fait à l’aide d’un algorithme dérivé de l’algorithme de Needleman et Wunsch utilisé dans le domaine de la Bio-Informatique. Les deux approches sont testées sur des données artificielles ainsi que sur des données extraites d’un simulateur très réaliste d’un des systèmes du LHC et montrent de bons résultats. / In the context of the CERN Large Hadron Collider (LHC), a large number of control systems have been built based on industrial control and SCADA solutions. Beyond the complexity of these systems, a large number of sensors and actuators are controlled which make the monitoring and diagnostic of these equipment a continuous and real challenge for human operators. Even with the existing SCADA monitoring tools, critical situations prompt alarms avalanches in the supervision that makes diagnostic more difficult. This thesis proposes a decision support methodology based on the use of historical data. Past faults signatures represented by alarm lists are compared with the alarm list of the fault to diagnose using pattern matching methods. Two approaches are considered. In the first one, the order of appearance is not taken into account, the alarm lists are then represented by a binary vector and compared to each other thanks to an original weighted distance. Every alarm is weighted according to its ability to represent correctly every past faults. The second approach takes into account the alarms order and uses a symbolic sequence to represent the faults. The comparison between the sequences is then made by an adapted version of the Needleman and Wunsch algorithm widely used in Bio-Informatic. The two methods are tested on artificial data and on simulated data extracted from a very realistic simulator of one of the CERN system. Both methods show good results.

Made available in DSpace on 2016-06-02T19:50:13Z (GMT). No. of bitstreams: 1 Retido.pdf: 19733 bytes, checksum: 6aad255badc436a06364517de2344ab6 (MD5) Previous issue date: 2011-11-28 / Brazil is one of the greatest sugarcane producers of the world, with figures that exceeds 620 million tons in 2010/2011 harvest season. There is an expectation of strong increase of Brazilian sugarcane production in next years due to increase in sales estimulated by the low production cost of sugar and alcohol and also the increase of the internal and external demands for ethanol, in substitution to fossil fuels. At the same time, environmental issues led the publication of a specific legislation that established a schedule to the next years to stop sugarcane burning previous to hand cutting, a traditional activity. This legal restriction brought a new scenario, as an increasing amount of biomass, that used to be burnt, will be available for other uses such as ethanol extra production, by technologies still in development or to energy generation, similar to what is done with bagasse (by means of cogeneration). Independent of its use, sugarcane and its biomass processing configures a complex operation as big volumes of materials are handled using high cost equipment which a high interaction among them. Several systems can be configured to do this task, varying equipments and settings of the operations performed by them. The selection of equipment and operational proceedings is one of the main tasks of managers at sugarcane mills. In order to help in decision taking situations, in this study, a discrete event simulation model was designed and modeled to represent sugarcane harvesting systems with biomass recovery. Conventional sugarcane harvesting and partial cleaning sugarcane harvesting were represented in a unique simulation model, as well as the correspondent alternatives of biomass recovery and delivery at mills. The operational characteristics of these systems were previously set in the model and can be modified through electronic spreadsheets, interfaced with the simulation model that manages the input and output of data. Field tests were done to evaluate equipment performance and generate data to the simulation model, which was used in two studies. In the first study, three sugarcane harvesting and biomass recovery systems were simulated using the data collected at each field test, representing those systems differently, under their own observed conditions. In the second study, the three systems were again compared, however, under the same conditions, with the same set of assumptions, in order to permit their comparison in equal basis. All scenarios considered a typical mill operation that processes two million tons of sugarcane per harvest season. The simulation model enabled the evaluation of the selected systems considering sugarcane and biomass production as well as their economic evaluation. / O Brasil é um dos maiores produtores mundiais de cana-de-açúcar, com processamento superior a 620 milhões de toneladas na safra 2010/2011. A perspectiva para os próximos anos é de forte crescimento da produção de açúcar e de etanol, impulsionada pelo aumento das vendas decorrentes do baixo custo de produção e do aumento do consumo de etanol, interno e externo, em substituição ao uso de combustíveis fósseis. Simultaneamente, a maior preocupação ambiental levou à implantação de leis que estipulam a redução gradativa da queima controlada, tradicionalmente utilizada no manejo da cana-de-açúcar previamente ao corte manual. Este fato estabeleceu uma mudança de cenário, pois, a biomassa que outrora era queimada, surgiu como subproduto passível de utilização, seja para a fabricação de etanol, por tecnologias ainda em desenvolvimento para escala comercial, ou para a geração de energia, da mesma forma que o bagaço (cogeração). Independente da destinação, o processamento da cana-de-açúcar e de sua biomassa caracteriza um sistema logístico complexo, pois grandes volumes de material são movimentados, utilizando equipamentos de alto custo e com algo grau de interação. Diversos sistemas podem ser configurados com a finalidade de processamento da cana e da biomassa, variando equipamentos e operações. A seleção destas opções constitui uma das principais tarefas da gestão das operações das usinas. Com o objetivo de auxiliar tomadas de decisão, neste trabalho desenvolveu-se um modelo de simulação de eventos discretos dos sistemas de colheita de cana-de-açúcar com aproveitamento da biomassa. Os processos de colheita de cana-de-açúcar com limpeza convencional e colheita com limpeza parcial foram representados em um único modelo, bem como as alternativas de recolhimento e entrega da biomassa. As características operacionais dos sistemas foram parametrizadas, sendo possível configurar cenários de interesse por meio de planilhas eletrônicas, que interagem com o modelo e facilitam a inserção de dados e a análise de resultados. Ensaios de campo foram conduzidos para testar o desempenho dos equipamentos e gerar dados para o modelo de simulação, que foi usado para realizar dois estudos. No primeiro estudo simularam-se três alternativas de sistemas de colheita de cana-deaçúcar e processamento de biomassa diferentemente, reproduzindo as condições operacionais observadas em cada ensaio de campo. No segundo estudo, os três sistemas foram novamente comparados, porém em igualdade de condições, com o mesmo conjunto de premissas, de forma a poder compará-los. Em todos os cenários adotou-se como padrão uma usina com capacidade de processamento de dois milhões de toneladas de cana por safra. O modelo permitiu avaliar os sistemas selecionados, tanto do ponto de vista operacional, com análise das produções de cana-de-açúcar e de biomassa, como também do ponto de vista econômico.

Made available in DSpace on 2016-12-12T17:38:33Z (GMT). No. of bitstreams: 1 Daniel Gumiero Noronha Maas.pdf: 6258702 bytes, checksum: 06207c47266ccded357fbb819c6ae9bf (MD5) Previous issue date: 2014-09-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work presents a multilayer architecture for fault diagnosis in embedded systems that allows a better discrimination of the type and source of the failure, providing an accurate and assertive diagnosis. This architecture contemplates the necessary interfaces to allow integration of this diagnostic framework in the embedded system and also considers the treatment of diagnostic information for recovery system actions purposes, or simply allows the externalization of such information. This work considers the diagnosers designed according to the methodology of fault diagnosis in DES modeled by automata. Once designed the diagnosers are implemented in ANSI C language through an automated software generation tool, and finally incorporated into the main product software where it intends to perform the diagnosis. This architecture diagnosis was then applied in a case study for Frost Free refrigerator, for which the diagnosers were designed then were implemented in software and subsequently validated in order to confirm the effectiveness of the diagnosers, of the proposed architecture beyond the C language conversion process. / Este trabalho apresenta uma arquitetura de diagnóstico multicamadas para detecção de falhas em sistemas embarcados, que permite uma melhor discriminação do tipo e origem da falha, possibilitando um diagnóstico mais preciso e assertivo. Esta arquitetura contempla as interfaces necessárias para permitir a integração no sistema embarcado e também considera o tratamento das informações de diagnóstico para fins de ações de recuperação do sistema, ou simplesmente a externalização destas informações. Neste trabalho, consideram-se os diagnosticadores projetados conforme a metodologia de diagnóstico de falhas em SEDs modelados por autômatos. Uma vez concebidos, os diagnosticadores são implementados em linguagem ANSI C, através de uma ferramenta de geração automática de software, e finalmente incorporados ao software principal do equipamento onde se pretende realizar o diagnóstico. Esta arquitetura de diagnóstico foi então aplicada em um estudo de caso para um refrigerador Frost Free, para o qual foram projetados os diagnosticadores, em seguida os mesmos foram implementados em software e posteriormente validados a fim de comprovar a eficácia não somente dos diagnosticadores mas também da arquitetura proposta, além do processo de conversão dos mesmos em linguagem de software.