Event-based models find frequent usage in fields such as computational physics and biology as they may contain both continuous and discrete state variables and may incorporate both deterministic and stochastic state transitions. If the state transitions are stochastic, computer-generated random numbers are used to obtain the model solution. This type of event-based computations is also known as Monte-Carlo simulation. In this thesis, I study different approaches to execute event-based computations on parallel computers. This ultimately allows users to retrieve their simulation results in a fraction of the original computation time. As system sizes grow continuously or models have to be simulated at longer time scales, this is a necessary approach for current computational tasks. More specifically, I propose several ways to asynchronously simulate such models on parallel shared-memory computers, for example using parallel discrete-event simulation or task-based computing. The particular event-based models studied herein find applications in systems biology, computational epidemiology and computational neuroscience. In the presented studies, the proposed methods allow for high efficiency of the parallel simulation, typically scaling well with the number of used computer cores. As the scaling typically depends on individual model properties, the studies also investigate which quantities have the greatest impact on the simulation performance. Finally, the presented studies include other insights into event-based computations, such as methods how to estimate parameter sensitivity in stochastic models and how to simulate models that include both deterministic and stochastic state transitions. / UPMARC

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[pt] Os sistemas de agendamento de consultas tradicionalmente realizam as marcações dos pacientes em intervalos fixos de tempo, sem levar em consideração diversos fatores de complexidade do sistema de saúde. Isso pode causar mão de obra ociosa em alguns períodos do dia e longas filas de espera de pacientes em outros momentos. Nesse contexto, esta dissertação tem como intuito propor uma nova política de agendamento para uma clínica especializada em cirurgia bariátrica do Rio de Janeiro, considerando os fatores desse sistema: tempos de serviços estocásticos, impontualidade do paciente, atrasos e interrupções do serviço, e presenças de no-shows. Esta dissertação analisou diversos cenários com overbooking (marcação de pacientes adicionais), e testou as principais políticas por meio de simulação, propondo a mais adequada para a clínica. As 18 políticas de agendamento aplicadas foram encontradas através de uma extensa revisão sistemática da literatura. Com a utilização da política de agendamento OFFSET, foi possível aumentar o número de atendimentos em 30 por cento para o agendamento do principal provedor da clínica, mantendo o nível de serviço prestado. Além disto, foi proposta uma nova política de agendamento, denominada DOME CYCLE, que teve resultados superiores às demais políticas da literatura na média dos cenários realizados. / [en] Appointment-scheduling systems traditionally schedule patient appointments at fixed intervals, without taking into account several complexity factors of health-care system. This schedule can make the server idle at certain times of the day and can produce long queues of patients at other times. In this context, the objective of this study is to propose a new scheduling policy for a clinic specialized in bariatric surgery in Rio de Janeiro, considering the following factors of this system: stochastic service times, patient unpunctuality, delays and interruptions of the provider and presences of no-shows. This study analyzed several scenarios with overbooking, and tested the main policies with a simulation model, proposing the most appropriate for the clinic. The 18 scheduling policies applied were found through an extensive systematic review of the literature. With the use of the OFFSET scheduling policy, it was possible to increase the number of appointments by 30 percent to the scheduling of the main clinic provider, maintaining the level of service provided. In addition, a new scheduling policy, called DOME CYCLE, was proposed, which has outperformed the other policies in the average of the tests performed.

The world becomes more integrated and sophisticated, especially in the birth of advanced technologies, which have influenced all life aspects. Automated systems could be considered an example of those aspects, which have been affected by recent changes in today’s life. The competition in the market is putting increasing pressure on different manufacturing organizations to find the best methods that enable them to stay up to date with the latest technologies in the industrial field. One of the most famous dilemmas that exist in this field is designing an efficient and flexible material handling system. This issue draws the attention of both decision-makers in different companies and software developers who put considerable effort into making that desired system real. Inclusive research needs to be performed to obtain such a system, and the most significant part of the research that requires special attention is the applied methodology.The approach to be adapted determines the degree of stability of a particular material handling system to function effectively in the case studied. Several methods are available and could be implemented to design that effective system such as meta-heuristic algorithms, and approaches that depend on simulation software tools. The latter approach, which is the simulation approach, seems to get increasing attention from developers of the industrial system since it plays a vital role in reducing the cost and preserving available resources. Besides, it helps predict future changes and scenarios of the system to be analyzed.In this project, a discrete-event simulation model was built for the proposed layout of the main shop floor owned by a Swedish manufacturing company. The corporation located in the south of Sweden, and it produces a vast range of manufacture of goods. The chosen methodology is a combination of lean, simulation, and optimization approaches. It has been implemented on the proposed layout in which material is handled into production lines by using automated guided vehicles (AGVs) as a means of transportation. The analysis of results shows potential benefits, where the production process became more efficient and organized since the operational cost has been reduced by decreasing the number of required vehicles. Moreover, the simulation approach facilitated testing new ideas and designing improved scenarios without the necessity to change the current state of the factory layout or disturbing the regular activities.

Trends such as increasing awareness of sustainable production, shorter product life cycles and personalised products create challenges for the mining industry. A solution to these challenges may be a functional product business model, where the provider sells the hardware’s function under a service contract and is responsible for delivering the combination of hardware and services over the duration of the contract. Under a functional product contract, it is of great importance to predict the availability performance of the hardware. For the mining company to strengthen its competitiveness even further, the reliability and maintainability are also crucial factors to reduce costs, maximise profits, minimise downtime, and improve forecasting of operating hours. The feasibility of performance modelling would be increased if it could be performed by a tool.In prior research related to the reliability of mining vehicles in underground mines, a research gap for drilling rigs was identified. The aim of the thesis was to build a prototype tool and develop a realistic test case to apply it to as a demonstration of how it can help mining vehicle (drilling vehicle) providers understand the impact of their failure modes, particularly from the perspective of providing those vehicles under functional product contracts. The focus was to develop a tool that can be accessible for decision makers within mine operating and mine vehicle provider companies who are not specialists in reliability and maintenance modelling.A simulation model was developed in JaamSim, a graphical user interface developed in Qt designer and the integration between them developed in the Python programming language. A realistic test case was constructed with the purpose of imitating a jumbo drill rig, specifically the Boomer M2 manufactured by Epiroc, used to develop tunnels in an underground mine. Three critical failure modes of the Boomer M2 were identified. Simulations of the test case show that the bent boom arm failure mode had greatest influence on the availability of the drill rig.The developed prototype tool demonstrates the value of decision support tools for measuring the impact of failure modes on functional product contracts and its potential for aiding their negotiation and adoption. The tool has a low complexity regarding usage which should increase its usefulness for decision makers. To increase the tools usefulness further, extending its flexibility of application to other mining vehicles and different maintenance policies has been identified as the next steps for future work.Key words:

OMNeT++ is a discrete-event simulator commonly used to build various network simulations. It can be extended by INET framework that supplies models of protocols and devices from TCP/IP environment. This paper explores current capabilities of INET to model IPv6, particularly routing. Implemented extension includes modules of dual-stack router and dual-stack host that support XML-based configuration of IPv6 addressing and static routing. We also introduce an OSPFv3 module that implements most of auxiliary features and is ready for future development of the routing protocol core.

The competition between manufacturing companies is constantlyincreasing. There is therefore a need for continuously improvingproduction control and production planning. The requirements arepartly founded on higher customer expectations on quality anddelivery precision. These requirements make manufacturing operationsmore demanding. To become more competitive, companies often turn tovirtual engineering tools with the intention of finding improvementsproposals that are not always completely obvious. The aim of this thesis work was to identify bottlenecks that limitsystem line production with the help of discrete event simulationand to identify improvement proposals that were able to reduce theproduction lead time. The work has been carried out at ABB inLudvika at the department for manufacturing the outer casing forpower transformers. The reliability of the study was ensured byusing a mixture of qualitative and quantitative data collectionmethods that complemented each other appropriately. Process mappingand collected data were the bases a simulation model, which is thebasis for the achieved work result. Analysis of the simulation results gave strong indications that aspecific operation in the production line needed to be improved andthe need to better balance operator capacity within the line. Theprocess mapping and data analysis highligthted the need for thecompany to work more with process standardisation. The finalimprovement proposals submitted to the company are intended toincrease the delivery precision and production capacity / Konkurrensen mellan tillverkande företag ökar ständigt, behovet avkontinuerlig effektivisering av produktionsstyrning och planering ärsåledes ett faktum. Tillverkning försvåras samtidigt då kunderförväntar sig allt mer kvalitativa och unika produkter med högleveransprecision. För att bli mer konkurrenskraftig vänder sig oftaföretag till virtuella hjälpmedel med avseendet att finnaförbättringsförslag som inte alltid är helt självklara. Syftet med arbetet var att identifiera eventuella flaskhalsar sombegränsar produktionen med hjälp av händelsestyrd simulering och attidentifiera förbättringsförslag som påverkar produktionskapaciteten.Arbetet har utförts på ABB i Ludvika vid avdelningen förtillverkning av ytterhöljet till transformatorer. Studienstillförlitlighet säkerställdes genom användandet av en blandningmellan kvalitativa och kvantitativa datainsamlingsmetoder somkompletterade varandra. Processkartläggning och datainsamling vargrunden för att ta fram en valid simuleringsmodell som var grund fördet uppnådda arbetsresultatet. Analys av simuleringsresultatet gav starka indikationer på att enspecifik operation i produktionen behövde justeras samt attföretaget behöver jobba med balansering av operatörs resurser föratt bättre möta kapacitetsbehovet. Utöver detta finns det ettfortsatt behov att arbeta med process standardisering. Deslutgiltiga förbättringsförslagen som lämnats till företaget ärvägledande för att öka leveransprecisionen ochproduktionskapaciteten.

LKAB hanterar en av världens största malmkroppar vid en underjordsgruva i Kiruna. I samband med deras gruvbrytning uppstår stora mängder avfall som måste hanteras korrekt. De avfallsanläggningar som finns på området har idag platsbrist, därför finns incitament att bygga nya anläggningar. Inför utformningen av dessa nya anläggningar behöver avfallsflöden inventeras och analyseras. I detta arbete har det skett med diskret händelsesimulering baserad på historisk data. På grund av osäkra parametrar har flera scenarion tagits fram. Utformningen av anläggningarna beror på vilken kapacitet de förväntas ha, vilket är beroende av hur ofta anläggningarna ska tömmas och hur mycket avfall som förväntas uppstå på gruvområdet. För att sedan hitta bästa möjliga placering på de nya anläggningarna har ett modifierat anläggningslokaliseringsproblem tillämpats. Den optimala placeringen är i den norra delen av gruvområdet och minskar den totala körsträckan. Placeringen påverkas inte av större flöden. / In Kiruna the company LKAB has an underground mine with one of the largest iron ore quantities in the world. When producing the iron ore, a lot of waste arise that has to be taken care of in a correct way. Due to lack of space in todays waste facilities, there exists incentives to build new ones. To be able to design these new facilities, the flows of waste has to be investigated and analyzed. This has been done by discrete-event simulation based on historical data. Since some of the collected parameters are uncertain, different scenarios have been tested. The design of the facilities are dependent on what capacity they are expected to store, which is dependent on how often the facilities will be emptied and how large quantities will arise in the mining area. To find an optimal placement for the new facilities, a modified facility location problem has been implemented. The optimal placement is in the north part of LKAB’s mining area and will lower the total driving distance. The optimal placement will not be affected by larger flows.

This master thesis has been performed in association with Blekinge Institute of Technology and in collaboration with the company Dynapac Compaction Equipment AB. The thesis aims to investigate how Discrete Event Simulation (DES) can be used for value and sustainability design concept assessments in early design stages. The research is made by investigating the example of simulating the lifecycle of a double drum asphalt compactor. The model is created in the computerbased DES software Simio LLC, where the captured data of the compactor´s lifecycle performances are linked to a Net Present Value (NPV) model and a sustainability assessment. The model is then further explored and evaluated in the Decision Arena, located at Blekinge Institute of Technology.  The simulated model is created to approach a ‘lifelike’ lifecycle of the machine, containing the compactor´s ordinary usage in road construction. This includes operations in sidewalk, parking lot and pothole repair scenarios. The model contain service, maintenance, transport, workers, resource sharing and more. The model is connected to MS Excel to transfer data. The life cycle performances are captured in the model and used to estimate the cost parameters of energy -, water -, maintenance -, service - and transportation energy cost within the NPV model. The CO2 – emission for fuel consumption and transport, together with the total water consumption in the sustainability assessment.  The outcome of the thesis showed that the method gave good results for developing new design configurations in the early phases in product development. The method could support designing towards sustainable and long-term solutions and collaborations over the sectors (i.e. between stakeholders, engineers, designers, non-experts and more). The outcome in the specific case resulted in successfulness of capturing all lifecycle performances of the machine and linking them to the mentioned parameters. The research question is, however, generic and the investigation for the specific case study uses assumptions and up- and down scaled data to protect the company secrecy. For future work, the method together with Internet of Things (IoT), Digital Twin or Industry 4.0 could be in high interest to investigate further. / Detta examensarbete har blivit utfört i association med Blekinge Tekniska högskolan och i samarbete med företaget Dynapac Compaction Equipment AB. Syftet med projektet är att undersöka hur diskret händelsesimulering (DES) kan användas för värde - och hållbarhets bedömning för olika designkonfigurationer, i tidiga skeden av produktutvecklingen. Arbetet är utfört genom att tillämpa exemplet av att simulera livscykeln för en asfaltsvält med dubbla trummor. Simuleringsmodellen är framställd genom det databaserade DES programmet Simio LLC, där utdata för maskinens livscykelprestanda tas fram och kopplas till en Net Present Value (NPV) modell och en hållbarhetsdömning för maskinen. Simuleringsmodellen utforskas och bedöms sedan vidare i ’Decision Arena’ på Blekinge Tekniska Högskola.  Den simulerade modellen är framställd för att eftersträva en verklighetstrogen livscykel av maskinen, innehållande dess vanliga användningsområden inom vägarbete. I livscykeln inkluderas operationer av trottoarer, parkeringsplatser och reparationer av hål i vägbanor. Modellen innehåller även service och underhåll, transport, arbetare/anställda, resursdelning med mera. Modellen är kopplad till MS Excel för att föra över in- och utdata mellan programmen. Maskinens livscykelprestanda är hämtat från modellen och använt till att uppskatta kostnadsparametrarna för energi, vatten, underhåll, service och energi under transport i NPV – modellen. Maskinens CO2 – utsläpp för bränsleförbrukning och transport, tillsammans med vattenkonsumtionen i hållbarhetsbedömningen. Arbetet visar på goda resultat för att utveckla nya desginkonfigurationer i de tidiga skedena inom produktutveckling. Metoden kan stödja utformning mot hållbara och långsiktiga lösningar, samt förstärka samarbeten över sektorerna (dvs. mellan intressenter, ingenjörer, designers, icke-experter med mera). Utfallet för det specifika fallet resulterade i framgång med att fånga upp maskinens livscykelprestanda och koppla dessa till de ovan nämnda parameterana. Forskningsfrågan är dock generell och utredningen för den specifika fallstudien använder uppskattningar och upp- och nerskalade data för att skydda företagets sekretess. För framtida arbete, kan metoden tillsammans med Internet of Things (IoT), Digital Twin och Industry 4.0 vara av stort intresse för att undersöka.

Firms today maintain complex supply chains containing many dependent stages to manufacture a product to the end customer. Here lies a dilemma, keeping extensive inventory generate higher customer satisfaction by enabling quick deliveries. This increase in inventory, however, comes at an increase in costs. Finding the balance between minimizing costs and increasing customer satisfaction is difficult. The search to solve this dilemma has led to the development of research in the area of inventory control. For long, optimization models have been developed to improve the supply chain holistically, from raw material-to-customer. Those approaches, however, have not been possible to apply in practice by being too computationally demanding. Also, they imply organizational adjustments that create issues beyond the optimization flow of materials. It explains why, despite significant technolog- ical advancements, many firms prefer to use non-holistic approaches. This thesis evaluates the tangible effect of using holistic optimization. The objective of this thesis’ is to determine optimal stock levels between dif- ferent stages of production. The method used is an optimization of inventory, stemming from Inventory Control Theories. Inventory optimization is at the cross- roads between logistics, economics, and management. The thesis builds on a case of inventory optimization identified at a large manufacturing firm. The literature in inventory optimization has indicated that inventory and customer services is a domain of continuous development. This thesis focuses on the adequation between total inventory cost and the customer service level. The method used to answer this question is the Multi-Echelon optimization model. This model seeks to optimize reorder points and reorder quantities. A comparison to the Single-Echelon model and a Base-Case allows for evaluation of the performance, discrete event simulation based on a company’s supply chain measures the effect. The result shows that the Multi-Echelon optimization model outperforms the two non-holistic models. This thesis shows the triple advantages of the Multi-Echelon optimization allowing for leaner manufacturing system by 1- reduction of waste, 2- less unproductive capi- tal tied up in inventory, and 3- adding value by increasing customer satisfaction. Other areas of inventory optimization in manufacturing should be able to take ad- vantage of the Multi-Echelon optimization model to manage materials stock-levels, delivery flows, and customer satisfaction. / Idag bedriver företag komplexa försörjningskedjor med många relaterade produk- tionssteg för att försörja sin efterfrågan. Dilemmat är att antingen ha stora lager för att säkerställa både snabb kundleverans och hög kundnöjdhet vilket kräver mycket bundet kapital. Alternativet är att spara pengar genom mindre lager men riskerar då att inte kunna leverera inom önskad tid och minska kundnöjdheten. Att hitta en balans är svårt. För att lösa problemet har forskning inom området lager- styrning ökat. Optimeringsmodeller har länge utvecklats för att förbättra försör- jningskedjor. De har inte kunnat appliceras i många företag p.g.a. avsaknaden av beräkningskraft och behovet att förändra organisationen utöver optimeringen. Det förklarar varför många företag, trots teknisk utveckling, fortfarande inte an- vänder ett helhetsperspektiv. Denna uppsats utvärderar de påtagliga effekterna vid holistisk optimering av produktion, lagerhållning, och kundleverans. Målet med uppsatsen är att fastställa optimala lagernivåer mellan de olika stegen inom en produktionskedja. Metoden som används är ”Multi-Echelon” op- timering och härstammar från området ”Inventory Control Theories”. Det är en blandning av logistik, ekonomi, och administration. Lageroptimering är ett ämne i konstant utveckling där kundnöjdhet blivit allt viktigare. Modellen optimerar när en ny beställning av material ska ske, samt dess storlek. Modellen utvärderas genom att jämföra prestationen med en ”Single-Echelon” modell och en grund- modell genom diskret händelsesimulering som är baserad på ett företags försör- jningskedja. Resultaten visar att ”Multi-Echelon” optimeringsmodellen presterar bättre än de två icke-holistiska modellerna vad gäller totalkostnad och kundser- vicenivå. Uppsatsen visar att ”Multi-Echelon” optimeringsmodellen har fördelar inom alla tre områdena: smidigare produktion genom mindre spill, mindre bun- det kapital krävs, och den ger en ökad kundnöjdhet genom säkrare leveranser inom ”rätt” tid. Andra områden inom tillverkningsindustrin borde kunna ap- plicera ”Multi-Echelon” optimering för att hantera sina lagernivåer, produktion, leveransflöden, och kundnöjdhet.