A multi-criteria decision support system for a routing problem in waste collection

Autor proofThis work presents a decision support system for route planning of vehicles performing waste collection for recycling. We propose a prototype system that includes three modules: route optimization, waste generation prediction, and multiple-criteria decision analysis (MCDA). In this work we focus on the application of MCDA in route optimization. The structure and functioning of the DSS is also presented. We modelled the waste collection procedure as a routing problem, more specifically as a team orienteering problem with capacity constraints and time windows. To solve the route optimization problem we developed a cellular genetic algorithm. For the MCDA module, we employed three methods: SMART, ValueFn and Analytic Hierarchy Process (AHP). The decision support system was tested with real-world data from a waste management company that collects recyclables, and the capabilities of the system are discussed.FCT Fundação para a Ciência e Tecnologia, Project Scope: PEst-OE/EEI/UI0319/2

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

Joining of fibre-reinforced thermoplastic polymer composites by friction stir welding—A review

The objective of the current work is to show the potential of the friction stir welding (FSW) and its variants to join fibre-reinforced thermoplastic polymer (FRTP) composites. To accomplish that, the FSW technique and two other important variants, the friction stir spot welding (FSSW) and the refill friction stir spot welding (RFSSW), are presented and explained in a brief but complete way. Since the joining of FRTP composites by FSSW has not yet been demonstrated, the literature review will be focused on the FSW and RFSSW techniques. In each review, the welding conditions and parameters studied by the different authors are presented and discussed, as well as the most important conclusions taken from them. About FSW, it can be concluded that the rotational speed and the welding speed have great influence on heat generation, mixture quality, and fibre fragmentation degree, while the tilt angle only has residual influence on the process. The reduction of internal and external defects can be achieved by adjusting axial force and plunge depth. Threaded or grooved conical pins achieved better results than other geometries. Stationary shoulder tools showed better performance than conventional tools. Regarding the RFSSW, it has not yet been possible to deepen conclusions about most of the welding parameters, but its feasibility is demonstrated.info:eu-repo/semantics/publishedVersio

Pigments extraction from Cyanobium sp. a comparison between pressure-based and electric fields-based technologies

Pigments from cyanobacteria, in special carotenoids and phycobiliproteins, have been seen with considerable interest for industrial applications due to their bioactive properties and their natural product characteristics. The extraction of these compounds is focused on the methodologies of cell disruption and on the chemical solubility of the compounds. In this study, two different methods were optimised and evaluated in terms of pigments´ extraction from the marine cyanobacterium Cyanobium sp.: a continuous pressurized solvent extraction (CPSE) system, and an electric fields-assisted extraction system based in ohmic heating (OH). For each method, a Central Composite Design (23) was performed. Optimal conditions for each extraction method were then compared to determine the best method for the extraction of pigments from Cyanobium sp. In both optimisation and comparison steps, two extracts were obtained from the same biomass: an ethanolic extract (carotenoids-targeted) and a successive water extract (phycobiliproteins-targeted). The content and profile of carotenoids and phycobiliproteins and the respective antioxidant capacity of extracts were evaluated. OH provided the best ethanolic extract, with a carotenoids content of 41.6 ± 1.7 mg gDW-1, and total antioxidant capacity of 8.0 ± 0.3 mgTE gDW-1, representing an increase of 1.3-fold and 2.5-fold respectively, when compared to CPSE. Regarding the aqueous extract, both methods led to the same content of phycobiliprotein (135 ± 10.0 mg gDW-1), although OH led to an antioxidant capacity of this extract of 8.3 ± 0.3 mgTE gDW-1, 3.6-fold higher when compared to CPSE. In terms of profile, no major variation was found between extraction methods, being lutein, zeaxanthin, echinenone and -carotene the major carotenoids (>60 % of total carotenoids), and phycocyanin and allophycocyanin the only present phycobiliproteins (in a 1:2 ratio). In addition to the productivity and composition of the extracts, the design and applicability of the system must be considered. Once again, OH overtook the other methods due to the scalability and possible continuous operation. Overall, OH proved to be the best of the two methodologies for pigments co-extraction from Cyanobium sp..A PhD fellowship (reference SFRH/BD/136767/2018) for author Fernando Pagels was granted by Fundação para a Ciência e Tecnologia (FCT, Portugal) under the auspices of Programa Operacional Capital Humano (POCH), supported by the European Social Fund and Portuguese funds (MECTES). This work was financially co-supported by the strategical funding from FCT UIDB/04423/2020, UIDP/04423/2020 and UIDB/04469/2020; and the project ALGAVALOR – MicroALGAs: produção integrada e VALORização da biomassa e das suas diversas aplicações (POCI-01-0247-FEDER-035234), supported by the European Regional Development Fund and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

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

Comparação de dois algoritmos genéticos aplicados ao TOP

A recolha seletiva de resíduos sólidos urbanos para reciclagem é um processo dispendioso, especialmente quando realizado em grande escala. Um problema importante neste processo reside na gestão de uma frota, uma vez que atualmente as estratégias utilizadas geralmente têm baixa eficiência. O processo de recolha seletiva de resíduos sólidos urbanos pode ser modelado como um problema de encaminhamento de veículos, em particular como um Problema de Orientação de Equipas (TOP - Team Orienteering Problem). No TOP uma frota de veículos é incumbida de visitar um conjunto selecionado de vértices, de modo a maximizar o luvro total. O objetivo deste trabalho é o de otimizar o processo de recolha selectiva de resíduos sólidos urbanos ao abordar as questões relacionadas com a gestão de uma frota. Isso deve ser alcançado através do desenvolvimento de uma ferramenta de software que implementa um algoritmo genético para resolver o modelo desenvolvido. Neste artigo apresentamos e comparamos dois algoritmos genéticos através de experiências computacionais realizadas com instâncias de teste conhecidas da literatura. O uso de algoritmos genéticos para resolver o TOP mostra ser uma escolha acertada, pois o método é eficiente produzindo bons resultados num tempo aceitável.Fundos FEDER através do Programa Operacional Fatores de Competitividade – COMPETE e por Fundos Nacionais através da FCT – Fundação para a Ciência e Tecnologia no âmbito do Projeto: FCOMP-01-0124-FEDER-022674GATOP - Genetic Algorithms for Team Orienteering Problem (Ref PTDC/EME-GIN/ 120761/2010), financiado por fundos nacionais pela FCT / MCTES e co-financiado pelo by the European Social Development Fund (FEDER) through the COMPETE Programa Operacional Fatores de Competitividade (POFC) Ref FCOMP-01-0124-FEDER-020609

Avaliação do efeito bifidogênico da banana verde (Musa paradisiaca) sobre o trato gastrointestinal de Rattus norvegicus

Nos dias de hoje cada vez mais a população busca alimentos que além do seu valor nutricional normal, tenham alguma funcionalidade que favoreça a promoção da saúde de alguma forma. Nesse aspecto, um dos assuntos que vem sendo bem enfatizado são alimentos que tenham uma funcionalidade prebiótica. O presente trabalho visou demonstrar a funcionalidade da banana verde como uma fonte prebiótica, avaliando o seu fator bifidogênico sobre as Bifidobacterium do trato gastrointestinal, assim a banana foi usada para a suplementação na alimentação de Rattus norvegicus, no qual foi avaliado o fator bifidogênico e também a conversão alimentar e o ganho de peso. Foram utilizados 30 animais machos, com 4 semanas de vida, os quais foram divididos em 3 grupos de 10 indivíduos, sendo que no grupo A (grupo controle) foram administrados apenas água e ração, o grupo B além da água e da ração foram suplementados com um preparado da farinha da casca de banana verde diariamente e o grupo C além de água e ração foram suplementados com preparado da farinha da polpa de banana verde diariamente. Estes foram avaliados durante seis semanas, onde semanalmente foram feitas coletas de fezes frescas para a contagem de Bifidobacterium. Os dados obtidos a partir da contagem foram avaliados estatisticamente pelos testes ANOVA e Bonferroni, onde não foi constatada diferença significativa entre o grupo controle e o grupo suplementado com a farinha da casca (P>0,05), porém, o grupo suplementado com farinha da polpa de banana verde, apresentou aumento significativo na contagem de Bifidobacterium comparado aos outros dois grupos (P0,05). Desta forma, conclui-se que a farinha da polpa de banana verde, estimula o aumento de Bifidobacterium nas fezes