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Publications

Publications by CESE

2024

How to Prioritize Replenishment Orders in Demand Driven MRP: A Simulation Study

Authors
Fernandes N.O.; Guedes N.; Thürer M.; Ferreira L.P.; Ávila P.;

Publication
Lecture Notes in Mechanical Engineering

Abstract
Demand Driven Material Requirements Planning (DDMRP) assumes that a production order is generated for replenishment when the inventory position, given by the net flow equation, is below a given level. Literature on this production planning and control system suggests prioritizing open orders on the shop floor based on the inventory buffer status. However, the performance of buffer-oriented priority dispatching largely remains unknown. Using discrete event simulation, this study suggests that buffer-oriented dispatching based on the net flow equation outperforms due date-oriented dispatching rules and first-come-first-served. The performance impact depends, however, on the reorder quantity associated with the production orders. These results have important implications for industrial practice.

2024

Analysis of Evacuation Strategies for a 4-Star Hotel Using Simulation

Authors
Costa H.; Ferreira A.; Ferreira L.P.; Costa E.; Ávila P.; Ramos A.L.;

Publication
Lecture Notes in Mechanical Engineering

Abstract
Total evacuation time constitutes an important factor in the safety of any building. It is thus essential to devise an emergency evacuation plan, which will enable the safe evacuation of all the occupants in the shortest possible time. The main objective of this article was to examine and improve the evacuation process of a 4-star hotel located in the city of Porto, Portugal. To this end, one looked into 6 scenarios, by means of PathFinder simulation software, so as to determine the shortest total evacuation time and identify possible bottlenecks and congestion. The simulation model developed was tested to analyze the evacuation of 429 people from the hotel, based on the availability of the 3 accessible exit doors (central exit, side exit, spa exit) and elevators. Strategy 4 presented the shortest total evacuation time, with 536.0 s. Two other strategies which showed very similar times were 5 and 6, with 537.0 s and 537.5 s, respectively.

2024

Demand Driven Material Requirements Planning: Using the Buffer Status to Schedule Replenishment Orders

Authors
Fernandes, NO; Guedes, N; Thürer, M; Ferreira, LP; Avila, P; Carmo Silva, S;

Publication
INFORMATION SYSTEMS AND TECHNOLOGIES, VOL 1, WORLDCIST 2023

Abstract
Demand Driven Material Requirements Planning argues that production replenishment orders should be scheduled on the shop floor according to the buffers' on-hand inventory. However, the actual performance impact of this remains largely unknown. Using discrete event simulation, this study compares scheduling based on the on-hand inventory, with scheduling based on the inventory net flow position. Results of our study show that scheduling based on the former performs best, particularly when multiple production orders are simultaneously generated and progress independently on the shop floor. Our finds give hints that are important to both, industrial practice and software development for production planning and control.

2024

Analysis of the Impact of Automation on a Workstation at an Industrial Company Using Simulation

Authors
Costa, C; Ferreira, LP; Ávila, P; Ramos, AL;

Publication
Lecture Notes in Networks and Systems

Abstract
In everyday life, the production lines of companies are required to be flexible, rapidly adopting new processes and methods in order to ensure their competitiveness in the market. The main objective of this study was to analyze the impact of automation on a workstation at an industrial company which paints accessories. By means of simulation, one was able to identify several aspects that negatively affect the company’s overall capacity, namely reduced productivity and long cycle times. The digital tools developed through Visual Basic for Applications constituted the starting point for the automation of several repetitive and bureaucratic tasks which support decision-making, initiating the process of Digital Transformation at the organization. In economic terms, this improvement in the workplace can potentially reduce costs in the order of thousands of euros annually, in addition to increasing productivity thus improving the company’s general performance. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.

2024

Configurations and features of demand responsive transports

Authors
Dauer A.; Dias T.G.; de Sousa J.P.; de Athayde Prata B.;

Publication
Transportation Research Procedia

Abstract
The concept of Demand Responsive Transport (DRT) has been around for more than 40 years and is a promising mobility alternative when traditional public transport proves inadequate in terms of its effectiveness or efficiency, as is the case of low-density areas. DRT systems have a wide range of operational configurations, being highly adaptable to different contexts and environments. Therefore, the design of a DRT mobility solution can become a quite complex and challenging problem. To assist in the design of DRTs, this paper aims to present a comprehensive classification of DRT features and to identify some common design choices in different operational scenarios. The proposed classification is based on a review of reports from available literature and previous European DRT projects. In addition, an analysis of the most usual configurations for different purposes and scenarios is presented. In this research, the operational, demand, and administrative characteristics of DRTs are addressed. Demand aspects encompass features that directly influence trip demand, such as service areas, target passengers, and hours of operation. Operational features include characteristics that will affect daily operations as the type of stops, frequency of the operation, booking methodology, vehicle route, pick-up and drop-off locations, and the vehicle type used. Administrative characteristics address the relationship between consumers and the system, such as the purpose of the system, fares, visual identification of stops, and booking methods. Regarding the usual design choices, our survey shows that rural DRTs are primarily oriented to serve populations in need in low-density areas and to complement existing PT gaps, while urban DRTs are mainly viewed as a mobility alternative to fill existing PT gaps. Defining design patterns for peri-urban and multi-area DRTs presents challenges due to their transitional nature, thus combining attributes of both rural and urban systems.

2024

Factors Influencing Sustainable Poverty Reduction: A Systematic Review of the Literature with a Microfinance Perspective

Authors
Fonseca, S; Moreira, A; Mota, J;

Publication
Journal of Risk and Financial Management

Abstract
This research examined factors that help microfinance achieve sustained poverty reduction based on a systematic literature review (SLR). A search was conducted on the SCOPUS database up to December 2023. After analyzing hundreds of documents, a subset of 30 articles was subject to in-depth analysis, exploring factors and corresponding measurement indicators for sustainable poverty reduction in microfinance contexts. This article emphasizes that sustained poverty reduction is a gradual process requiring ongoing efforts from both Microfinance Institutions (MFIs) and governments. Two key success factors are empowering borrowers and ensuring the microfinance programs themselves are profitable. When implemented in an integrated and coordinated manner, these factors can empower individuals to escape poverty by fostering self-employment and income generation, ultimately reducing dependence on external support. Additionally, the study highlights the role of personality traits in influencing long-term entrepreneurial success. The findings provide valuable tools for MFIs and policymakers. MFIs gain a practical framework to guide their interventions towards sustained poverty reduction. Policymakers can leverage the identified factors and indicators when designing and implementing microfinance policies with a long-term focus on poverty alleviation. This study breaks new ground by presenting an operational framework that categorizes and integrates two critical factor groups: empowerment and beneficiary profitability. Furthermore, it links these factors to corresponding measurement indicators within a unified framework, enabling a more holistic assessment of poverty reduction efforts. © 2024 by the authors.

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