17 documents found, page 1 of 2
A simulation study of walking-workers assignment strategies based on work zones
Fernandes, Nuno O.; Thürer, Matthias; Matos, P.This study addresses an “U” shaped assembly line with walking workers and flexible worker assignments. Workers, rather than machines, are the constraining resource in a dual-resource production system. Assignment strategies for walking workers based on Takt Time or restricted time zones of overlap are compared under different production conditions, including processing time variability and worker efficiency con...
Flexible takt times through overlapping zones: an assessment by simulation
Thürer, Matthias; Fernandes, Nuno O.; Henriques, Marcelo F.N.Flexible takt times through overlapping zones: an assessment by simulation.
The DDMRP replenishment model: An assessment by simulation
Fernandes, Nuno O.; Djabi, Suleimane; Thürer, Matthias; Ávila, Paulo; Ferreira, Luís Pinto; Silva, Sílvio C.Demand-Driven Material Requirements Planning (DDMRP) has been proposed as a solution for managing uncertainty and variability in supply chains by combining decoupling, buffer management and demand-driven planning principles. A key element of DDMRP is its inventory replenishment model, which relies on dynamically adjusted inventory buffers rather than fixed stock levels. However, parameterization of these buffer...
Material flow control in make-to-stock production systems: an assessment of ord...
Thürer, Matthias; Fernandes, Nuno O.; Lödding, Hermann; Stevenson, MarkMaterial Flow Control (MFC) is a key element of production planning and control. The literature typically categorizes different MFC methods according to how material flow control is realized. This distinction overlooks that MFC decisions can be subdivided into three independent tasks that are executed as orders progress through the system: (i) order generation, (ii) order release, and (iii) production authoriza...
DDMRP relative priority for production execution: an assessment by simulation
Fernandes, Nuno O.; Thürer, Matthias; Silva, Sílvio do CarmoDemand-Driven Material Requirements Planning (DDMRP) was designed to improve supply chain performance in complex and uncertain environments. Literature on the topic suggests that production replenishment orders should be dispatched for execution based on the buffers’ penetration ratio of the products ordered, which is a measure of protection against stock depletion. However, the actual performance impact of thi...
Demand driven material requirements planning: using the buffer status to schedu...
Fernandes, Nuno O.; Guedes, Nelson; Thürer, Matthias; Ferreira, Luís Pinto; Ávila, Paulo; Silva, Sílvio do CarmoDemand Driven Material Requirements Planning argues that production re-plenishment 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 com-pares scheduling based on the on-hand inventory, with scheduling based on the inventory net flow position. Results of our...
Work faster, work in parallel, or work overtime? An assessment of short-term
Fernandes, Nuno O.; Thürer, Matthias; Costa, FedericaMany firms use short-term capacity adjustments to deal with demand changes over time, and a broad literature assesses when and where to adjust capacity. This study highlights that this may be dependent on the type of capacity flexibility used to actually realize the adjustment. By comparing for the first-time capacity adjustments by speeding up processing rates, working in parallel, or using overtime, significa...
Improving urgency-based backlog sequencing of jobs: an assessment by simulation
Fernandes, Nuno O.; Thürer, Matthias; Stevenson, Mark; Carmo-Silva, S.When order release is applied, jobs are withheld in a backlog from where they are released to meet certain performance targets. The decision that selects jobs for release is typically preceded by a sequencing decision. It was traditionally assumed that backlog sequencing is only responsible for releasing jobs on time, whereas more recent literature has argued that it can also support load balancing. Although th...
POLCA Control in Two-Stage Production Systems
Fernandes, Nuno O.; Thürer, Matthias; Mirzaei, Nima; Ferreira, Luís Pinto; Silva, Francisco J. G.; Carmo-Silva, SílvioPOLCA (Paired-cell Overlapping Loops of Cards with Authorization) is a decision support system for material flow control under Quick Response Manufacturing. It operates in the context of low-volume, high-mix, and cellular manufacturing. While there is an increasing literature on POLCA performance, current studies usually assume full availability of components (or parts) at assembly stations, neglecting parts ma...
Workload control and optimised order release: an assessment by simulation
Fernandes, Nuno O.; Thürer, Matthias; Pinho, Tatiana; Torres, Pedro; Silva, Sílvio do CarmoAn important scheduling function of manufacturing systems is controlled order release. While there exists a broad literature on order release, reported release procedures typically use simple sequencing rules and greedy heuristics to determine which jobs to select for release. While this is appealing due to its simplicity, its adequateness has recently been questioned. In response, this study uses an integer li...