Search results for "Strategy"

New trends in manufacturing processes research

2019

Research on manufacturing processes is further enriched and becomes stronger at the 47th North American Manufacturing Research Conference (NAMRC 47) at Penn State University, The Behrend College, Erie, Pennsylvania USA. Innovation is fundamentally connected to products or processes: the former being rarer and more difficult to be obtained, the latter is definitively related to economy, competitiveness and welfare of a nation. Furthermore, the research and success in innovation of processes permit also the proposition of innovative products. Manufacturing processes engineering is of primary interest for industries and new challenges are faced every day in order to reduce costs, increase comp…

Latest developments in manufacturing processes at NAMRC 45

2017

Manufacturing processes are tightly connected to innovation.They have been the key areas that support and influence a nation’scompetitiveness and economy since the eighteenth century. Asthe primary driving force behind economic growth, manufactur-ing processes enable and facilitate innovative products realization,ranging from heavy-duty machinery to hi-tech home electronics.In the past centuries, they have contributed significantly to moderncivilization and created the momentum that drives today’s econ-omy. Despite various achievements in manufacturing processes, weare still facing challenges due to growing complexity in manufac-turing operations, introduction of new manufacturing technolog…

Linear and nonlinear fractional hereditary constitutive laws of asphalt mixtures

2016

The aim of this paper is to propose a fractional viscoelastic and viscoplastic model of asphalt mixtures using experimental data of several tests such as creep and creep recovery performed at different temperatures and at different stress levels. From a best fitting procedure it is shown that both the creep one and recovery curve follow a power law model. It is shown that the suitable model for asphalt mixtures is a dashpot and a fractional element arranged in series. The proposed model is also available outside of the linear domain but in this case the parameters of the model depend on the stress level.

Investigation on fracture of epoxy-filled composites by acoustic emission

2016

Acoustic emission (AE) technique is widely used to monitor failure processes in composite materials includ-ing development of cracks and plastic deformations within the polymer matrix, fracture and debonding of inclusions, etc. In this study, the AE technique was applied investigating failure character of epoxy polymers with different content of nanofiller – fine polyethersulfone (PES) powder. Variation of material properties of the epoxy with 0, 5%, 7.5%, 10%, and 12.5% concentration (by weight) of the PES was assessed experimentally. Correlation between the PES content and the modulus of elasticity was found negligible. The same was characteristic for the tensile strength. Whereas, such a…

A multistage heuristic for storage and retrieval problems in a warehouse with random storage

2017

The warehouse is one of the essential components of logistics and supply chains. The efficiency of the whole chain is affected by the performance of warehouse operations and, more particularly, the storage and retrieval of goods. This paper considers a storage and retrieval problem in a real warehouse with random storage and different types of forklifts, depending on the locations they can access. The problem deals with selecting locations to store/retrieve a predefined set of pallets, assigning an adequately skilled forklift to each operation and determining the order in which each forklift will perform its operations so that the total employed time is minimized. The problem is solved heur…

A parallel variable neighborhood search approach for the obnoxious p -median problem

2018

Intelligent Multi-Start Methods

2018

Heuristic search procedures aimed at finding globally optimal solutions to hard combinatorial optimization problems usually require some type of diversification to overcome local optimality. One way to achieve diversification is to re-start the procedure from a new solution once a region has been explored, which constitutes a multi-start procedure. In this chapter we describe the best known multi-start methods for solving optimization problems. We also describe their connections with other metaheuristic methodologies. We propose classifying these methods in terms of their use of randomization, memory and degree of rebuild. We also present a computational comparison of these methods on solvi…

Heuristics for the capacitated dispersion problem

2020

An airline connection builder using maximum connection lag with greedy parameter selection

2014

Abstract This paper introduces a methodology for designing an airline connection builder (CB) and adjusting its parameter settings. The objective of the proposed CB is to construct relevant connections that attract passenger demand while avoiding operationally infeasible and commercially irrelevant connections. Using worldwide MIDT booking data, we examined the sensitivity of CB results to the setting of the standard CB parameters maximum connection time and geographical detour. We demonstrated that CB performance can be increased by replacing these two parameters with connection lag, a measure that combines the impact of connection time with geographical detour on the total travel time of …

A multi-objective approach for a project scheduling problem with due dates and temporal constraints infeasibilities

2014

In this paper, we study a multi-mode resource-constrained project scheduling problem (RCPSP) which considers time and work generalised precedence relationships with minimal and maximal time lags and due dates where each activity requires only one unit of resource (e.g. a worker, a machine, etc.). To find a feasible solution for this problem is NP-hard and therefore for instances where a feasible solution has not been found, an appropriate real-life approach would consist of providing the decision-maker with a collection of quality solutions with a trade-off between due dates and temporal constraints violations. We propose a multi-objective evolutionary algorithm for the generation of an app…