Microssimulação para avaliar o impacto da introdução de pré-semáforos em cruzamentos

Dissertação de mestrado em Engenharia de SistemasA resolução de problemas relacionados com a saturação dos cruzamentos consiste, geralmente, na construção de infraestruturas como pontes e túneis. Estas representam o tipo de soluções mais dispendiosas e, no cenário de crise em que vários países se encontram, torna-se necessário equacionar outro tipo de soluções, de menor custo. Assim, esta dissertação pretende fornecer uma resposta à tese de que é possível melhorar significativamente o desempenho de um cruzamento, através da utilização de pré-semáforos, nos acessos ao mesmo. Para este efeito, foi desenvolvido um modelo de microssimulação de tráfego, usando o SIMIO. Durante o processo de familiarização com esta ferramenta, foi efetuada uma comparação com o Arena. O modelo de tráfego desenvolvido é totalmente parametrizável, sendo possível alterar: o tipo de cruzamento (com ou sem pré-semáforos); a distância entre um pré-semáforo e os respetivos semáforos principais; o tempo de sinal verde dos semáforos e a intensidade de tráfego. Os dados introduzidos para modelar o sistema foram recolhidos através de observações no terreno e da bibliografia consultada. Definiram-se como KPI (Key Performance Indicators): o tempo médio de espera por veículo, o tamanho médio das filas e o fluxo de veículos por hora. Foi usado o modo de experiências de simulação do SIMIO, para avaliar o impacto que as alterações às propriedades do modelo produzem nos KPI. As experiências indicam que o tempo adequado de duração do sinal verde, em cruzamentos com pré-semáforos, se deve situar entre os 20 e os 30 segundos e que o melhor desempenho é atingido quando os pré-semáforos se encontram a 40 metros dos respetivos semáforos principais, contudo, constata-se que, para intensidades de tráfego moderadas ou baixas, a distância não influencia o desempenho do cruzamento. Comparando os desempenhos de um cruzamento com pré-semáforos com o de um com normal semaforização, verifica-se uma subida do teto máximo do fluxo do cruzamento em 15%, uma descida do tempo médio de espera em aproximadamente 1 minuto e 15 segundos e uma descida do tamanho médio das filas em aproximadamente 60 metros. Adicionalmente, também se verificou que existe sempre lucro no espaço ocupado pelas filas, tendo em conta o investimento necessário para implementação de pré-semáforos.The resolution of problems related to the saturation of traffic intersections usually consists in the construction of infrastructure such as bridges or tunnels. These represent the type of solutions most costly and, in the scenario of crisis in which several countries are, it becomes necessary to ponder another type of solution, of lower cost. Thus, this dissertation intends to provide an answer to the thesis that it is possible to significantly improve the performance of a traffic intersection, by using pre-signals, in its approaches. For this purpose, a traffic micro simulation model was developed, using SIMIO. During the process of familiarization with this tool, a comparison was made with Arena. The traffic model developed is completely parametrizable, being possible to change: the type of intersection (with or without pre-signals); the distance between a pre-signal and the respective main lights of each approach; the green light signal time of the traffic lights and the traffic intensity. The input data to model the system were collected through field observations and literature reviewed. The defined KPI (Key Performance Indicators) were: the average waiting time per vehicle, the average size of the queues and the flow of vehicles per hour. To evaluate the impact that changes to the model properties produce on the KPI, the simulation experiences mode of the SIMIO were used. These show that the proper time duration of the green light at traffic intersections with pre-signals should be between 20 and 30 seconds and that the best performance is achieved when the pre-signals are located 40 meters away of the respective main lights, however, it is found that for moderate and low traffic intensities the distance doesn‘t influence the performance of the intersection. Comparing the performance of an intersection with traffic signals with a normal one, it is noted an increase of the upper ceiling of the flow of the intersection in 15%, a decrease in the average waiting time in approximately 1 minute and 15 seconds and a decrease of the average size of the queues in about 60 meters. In addition, it was also found that there is always gain in the space occupied by the queues, taking into consideration the investment needed to implement pre-signals

Agent-based micro simulation to assess the performance of roundabouts considering different variables and performance indicators

Traffic congestion problems in intersections are usually solved by building infrastructures such as roundabouts. Several variables influence its performance, e.g. geometry, size and driving behaviour. Thus, it becomes necessary to compare these variables. This paper proposes a simulation model, developed to compare the performance of roundabouts, employing the object and agent modelling paradigms of Simio, to model the individual behaviour of vehicles. The results indicate the optimum size of roundabouts is around 40 meters of diameter and that the driving style has a greater influence on the performance of the roundabout than its unbalancing. In addition, it was found that roundabouts considering unbalancing and human behaviour decreased: The flow of vehicles in 8%, the waiting time per vehicle in 3 minutes, the queue size in 90%, the number of stops per vehicle in 88% and vehicles spent three times more fuel, than the roundabouts that did not consider these variables.(undefined)info:eu-repo/semantics/publishedVersio

Discrete simulation software ranking -A top list of the worldwide most popular and used tools

This paper documents a work on all-purpose discrete event simulation tools evaluation. Selected tools must be suitable for process design (e.g. manufacturing or services industries). Rather than making specific judgments of the tools, authors tried to measure the intensity of usage or presence in different sources, which they called "popularity". It was performed in several different ways, including occurrences in the WWW and scientific publications with tool name and vendor name. This work is an upgrade to the same study issued 5 years ago (2011), which in its turn was also an upgrade of 10 years ago (in 2006). It is obvious that more popularity does not assure more quality, or being better to the purpose of a simulation tool; however, a positive correlation may exist between them. The result of this work is a short list, of 19 commercial simulation tools, with probably the nowadays' most relevant ones.This work has been co-supported by SI I&DT project in joint-promotion nº 36265/2013 (HMIEXCEL) and by FCT Fundação para a Ciência e Tecnologia - project: PEst-OE/EEI/UI0319/2014. REFERENCESinfo:eu-repo/semantics/publishedVersio

Assessing the performance of a restaurant through discrete simulation in Simio

For the purpose of evaluating the level of service of a Portuguese self-service restaurant, a simulation model was developed in Simio. The purpose of such model was to quantify specific performance indicators. In this sense, data was gathered by conducting observations of the field, which allowed the authors to find relevant problems in the system. The simulation model was validated and, afterwards, simulation experiments were conducted, which suggested some changes that could be implemented, without reducing the performance of the restaurant and reduce the utilization of workers, who become available for other tasks with more added-value, such as supplying critical items (e.g., main dishes and soap). Moreover, the potential impact of the introduction of an information device used to warn workers responsible to supply items was assessed through simulation, indicating that it would lead to benefits both for customers and workers.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT –Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013 and by the Doctoral scholarship PDE/BDE/114566/2016 funded by FCT, the Portuguese Ministry of Science, Technology and Higher Education, through national funds, and co-financed by the European Social Fund (ESF) through the Operacional Programme for Human Capital (POCH)

A novel application of pre-signals to improve the performance of signalized intersections: Evaluation through simulation

To ponder less costlier solutions to solve traffic congestion problems at signalized intersections, this paper proposes a novel application consisting of using pre-signals. Hence, an agent-based traffic simulation model was developed, where it is possible to model different types of intersections - including roundabouts of different sizes - and quantify and compare their performance. By analyzing the simulation results, it was found that: on the intersection with pre-signals, an increase in the flow of 10% and 3% was registered, the vehicles spent 1 and 2 less minutes to cross the intersection and the fuel consumption was decreased in 22% and 44%, in comparison to regular intersections and roundabouts, respectively. Concerning the size of queues, it was noted that the queues of the regular intersection were 60 meters longer than the queues on the intersection with pre-signals and on the roundabout. Based on these findings, and by making cost assumptions, a small cost analysis was made, which indicates that at least 1 million € could be yearly saved.This work has been supported by FCT –Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019

Combining simulation and optimization models on a production line problem: A case study

To improve the performance of a production line of a company of the Bosch Group, an optimization model was developed, which produces the optimum allocation of tasks to workstations and workers, according to a set of constraints. These results can thereafter be used in the simulation model, to estimate performance indicators, which would be difficult to estimate with other approaches, namely: waiting times, times spent with displacements and utilization rates. Thus, the purpose of this paper is twofold. First, it describes the combined use of the optimization and the simulation models. Thereafter, it presents the results obtained for 2 scenarios: one without displacements and another with displacements. The former was used to compare the simulation and the optimization models, whilst the later was used to assess the impact of displacements in the production line. By analyzing the results, it was possible to verify that the displacements increased the total time required to produce the devices in more than 10%. Furthermore, it was shown that the displacements caused considerable changes in the remaining performance indicators, indicating the relevance of considering them. This work also brings insights to the Industry 4.0 by proposing an approach to virtualize a production line system, providing the benefits of the 3D visualization of the simulation tool used in this research.This research was partially sponsored by the Portugal Incentive System for Research and Technological Development. Project in co-promotion nº 002814/2015 (iFACTORY 2015-2018) and has been partially supported by FCT –Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019

A ranking of the most known freeware and open source discrete-event simulation tools

Freeware and open source simulation software can be of great relevant when applying simulation in companies that do not possess the required monetary resources to invest in traditional commercial software, since these can be unaffordable Even so, there is a lack of papers that contribute to literature with a comparison of opensource and freeware simulation tools. Furthermore, such existing papers fail to establish a proper assessment of these type of tools. In this regard, this paper proposes a study in which several freeware and open source discrete-event general purpose simulation tools were selected and compared, in order to propose a ranking based on the tools' popularity, considering several criteria. For this purpose, 30 criteria were used to assess the score of each tool, leading to a podium composed by SimPy, JSim and JaamSim. Further conclusion and future work are discussed in the last section.This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019 and by the Doctoral scholarship PDE/BDE/114566/2016 funded by FCT, the Portuguese Ministry of Science, Technology and Higher Education, through national funds, and co-financed by the European Social Fund (ESF) through the Operational Programme for Human Capital (POCH

Simulation of an automotive supply chain using big data

Supply Chains (SCs) are dynamic and complex networks that are exposed to disruption, which have consequences hard to quantify. Thus, simulation may be used, as it allows the uncertainty and dynamic nature of systems to be considered. Furthermore, the several systems used in SCs generate data with increasingly high volumes and velocities, paving the way for the development of simulation models in Big Data contexts. Hence, contrarily to traditional simulation approaches, which use statistical distributions to model specific SC problems, this paper proposed a Decision-Support System, supported by a Big Data Warehouse (BDW) and a simulation model. The first stores and integrates data from multiple sources and the second reproduces movements of materials and information from such data, while it also allows risk scenarios to be analyzed. The obtained results show the model being used to reproduce the historical data stored in the BDW and to assess the impact of events triggered during runtime to disrupt suppliers in a geographical range. This paper also analyzes the volume of data that was managed, hoping to serve as a milestone for future SC simulation studies in Big Data contexts. Further conclusions and future work are also discussed.This work has been supported by FCT (Fundacao para a Ciencia e Tecnologia) within the Project Scope: UID/CEC/00319/2019 and by the Doctoral scholarship PDE/BDE/114566/2016 funded by FCT, the Portuguese Ministry of Science, Technology and Higher Education, through national funds, and co-financed by the European Social Fund (ESF) through the Operational Programme for Human Capital (POCH)

Real-time supply chain simulation: a big data-driven approach

Simulation of Supply Chains comprises huge amounts of data, resulting in numerous entities flowing in the model. These networks are highly dynamic systems, where entities' relationships and other elements evolve with time, paving the way for real-time Supply Chain decision-support tools capable of using real data. In light of this, a solution comprising of a Big Data Warehouse to store relevant data and a simulation model of an automotive plant, are being developed. The purpose of this paper is to address the modelling approach, which allowed the simulation model to automatically adapt to the data stored in a Big Data Warehouse and thus adapt to new scenarios without manual intervention. The main characteristics of the conceived solution were demonstrated, with emphasis to the real-time and the ability to allow the model to load the state of the system from the Big Data Warehouse.This work has been supported by FCT - Fundacao para a Ciencia e Tecnologia within the Project Scope: UID/CEC/00319/2019 and by the Doctoral scholarship PDE/BDE/114566/2016 funded by FCT, the Portuguese Ministry of Science, Technology and Higher Education, through national funds, and co-financed by the European Social Fund (ESF) through the Operational Programme for Human Capital (POCH)

Simulation of an automotive supply chain in Simio: Data model validation

This paper presents a simulation model of the supply chain of a company of the automotive industry. The purpose of this paper is to use the presented model to validate the considered set of variables that we think are relevant to the problem. This approach was important as it allowed to consider a set of variables that could have been ignored if a different approach had been followed. It should be stressed that, due to privacy concerns, real data was not used, but rather random distributions assigned by the modeler. Notwithstanding, by recognizing that, for the data used, the outputs are in accordance to what happens in the real system, the authors concluded that the set of variables can be considered as validated. Yet, it is still necessary to further complement the model with additional available variables that were not included at this stage, due to its complexity, e.g., customer demand variability, uncertainty associated to suppliers' and impact of external events, such as transportation delays.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT –Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013 and by the Doctoral scholarship PDE/BDE/114566/2016 funded by FCT, thePortuguese Ministry of Science, Technology and Higher Education, through national funds, and co-financed by the European Social Fund (ESF) through the Operacional Programme for Human Capital (POCH)