Search results for "Operations Research"
showing 10 items of 1297 documents
Car sequencing versus mixed-model sequencing: A computational study
2014
Abstract The paper deals with the two most important mathematical models for sequencing products on a mixed-model assembly line in order to minimize work overload the mixed-model sequencing (MMS) model and the car sequencing (CS) model. Although both models follow the same underlying objective, only MMS directly addresses the work overload in its objective function. CS instead applies a surrogate objective using so-called sequencing rules which restrict labor-intensive options accompanied with the products in the sequence. The CS model minimizes the number of violations of the respective sequencing rules, which is widely assumed to lead to minimum work overload. This paper experimentally co…
Higher Education Internationalization: The Erasmus-Mundus network added value
2014
International audience; Higher education internationalization can play a major role in developing universities and students' capacities and their opportunities broadly throughout the world. Irrespective of contextual differences within and between countries, nearly all higher education institutions worldwide are engaged in international activities and are seeking to expand them. Engaging with the world is now considered part of the definition of quality in education and research. However, with the current crisis, possible tensions and counter reactions to the development of the internationalization can occur, such as an imminent resistance to a supposed denationalizing effect of internation…
A DEA-based transport heliports' efficiencies evaluation
2015
Purpose - The purpose of the study is the evaluation of the efficiencies of a group of small Italian airports and the comparison with a set of transport heliports to show the difference in the productivity of the two types of infrastructures. Design/methodology/approach - The methodology used for the evaluation is the data envelopment analysis (DEA). Findings - The better performance of the heliports compared to the small inefficient airports. Research limitations/implications - This research is limited by the field of application and the weaknesses of the DEA methodology. However, it could be the first step for further works that will include more accurate models. Practical implications - …
Formal Modeling and Discrete-Time Analysis of BPEL Web Services
2008
International audience; Web services are increasingly used for building enterprise information systems according to the Service Oriented Architecture (SOA) paradigm. We propose in this paper a tool-equipped methodology allowing the formal modeling and analysis of Web services described in the BPEL language. The discrete-time transition systems modeling the behavior of BPEL descriptions are obtained by an exhaustive simulation based on a formalization of BPEL semantics using the Algebra of Timed Processes (ATP). These models are then analyzed by model checking value-based temporal logic properties using the CADP toolbox. The approach is illustrated with the design of a Web service for GPS na…
Using the Rasch model to assess a University Service on the Basis of Students Opinions
2008
In this paper we use the Rasch model (RM) as a tool to measure the perceived quality of student services at the Reception Office of an Italian university faculty. This paper has both a substantive and a methodological aim. The former is concerned with measuring the service quality of the Reception Office, while the latter concerns the definition and validation of an instrument for measuring perceived quality. The sample comprised 273 students enrolled at the Faculty of Economics at the University of Palermo (Aiello F. Il modello di Rasch per la costruzione di uno strumento di misura della qualit`a di un Servizio. Ph.D. Thesis, University of Palermo, Palermo, 2005). The RM is applied to prod…
Scatter Search—Wellsprings and Challenges
2006
I came up with the idea of editing this volume in the summer of 2002 while working on the book "Scatter search methodologies and implementations in C" with Manuel Laguna in the University of Colorado at Boulder. There, Fred Glover kindly let me use his office, where I found a copy of the "Tabu Search Methods for Optimization" special issue that he edited in 1988 for the European Journal of Operational Research. This encounter made me realize that Scatter Search has reached a level of maturity as an optimization method that has parallels with what Tabu Search was experiencing in the late eighties. So I thought that the moment was perfect to embark on this project, which has been supported en…
Multiple-attribute decision support system based on fuzzy logic for performance assessment
2005
Abstract This paper deals with the problem of assessing the performance of a set of production units, simultaneously considering different kinds of information, yielded by a Data Envelopment Analysis, a qualitative data analysis and an expert assessment. The tool for integrating heterogeneous data is a model that applies fuzzy logic to decision support systems. The results obtained are a holistic performance assessment of each unit of the set and a ranking order of the units.
Hierarchical multi-criteria analysis for the selection of a triathlon
2018
Sports activities have an increasingly large impact in different fields: economy, tourism, environment, applied technology, social, culture, etc. This study analyses the most important criteria that triathletes take into account when choosing a triathlon event in Spain. The methodology used was Analytic Hierarchy Process (AHP), which quantifies the weighting of each criterion and sub-criterion in a survey. The survey was drawn up using 14 triathlete experts and was completed by 95 triathlon participants. The results show that the internal aspects associated with the development of the triathlon event, together with the proximity to the athlete's home, the layout and signage of the circuits …
Investigating the effect of residual stress on hydrogen cracking in multi-pass robotic welding through process compatible non-destructive testing
2021
Abstract In this paper, the effect of Welding Residual Stress (WRS) on the size and morphology of hydrogen-induced cracks (HIC) is studied. Four samples were manufactured using a 6-axis welding robot and in two separate batches. The difference between the two batches was the clamping system used, which resulted in different amounts of welding deformation and WRS. The hydrogen cracks were intentionally manufactured in the samples using a localised water-quenching method, where water was sprayed over a specific weld pass in a predetermined position. The Phased-Array Ultrasonic Testing (PAUT) system was implemented during the welding process (high-temperature in-process method), to detect the …
Minimizing the cycle time in serial manufacturing systems with multiple dual-gripper robots
2006
Robots are being used more and more extensively as material-handling systems for automated manufacturing systems. This is especially true for dual-gripper robots whose in-process buffer (the robot's second gripper) constitutes a further element of flexibility. When the number of stations to be served is high and the set of activities the robot must execute is great, the system throughput may depend on robot capability rather than on process times. In such conditions, the use of several robots leads to an increase in system productivity. Obviously, the design and the management of such a handling system becomes more complex: the minimum number of robots required, the work stations to be serv…