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Publications

Publications by CESE

2012

Input-output control order release mechanism in a job-shop: How workload control improves manufacturing operations

Authors
Do Rosario Alves Moreira, M; Alves, RAFA;

Publication
International Journal of Computational Science and Engineering

Abstract
This paper presents and evaluates an order release decision rule in a job-shop, based on the input-output control concept. The order release mechanism is part of a global decision-making scheme that includes four main decisions: accept/reject orders, define the order's due date, release the accepted jobs and dispatch it on the shop floor. This paper also presents an evaluation of two acceptance rules, four release mechanisms, and two dispatching rules, using four levels of due date tightness. Extensive simulation experiments were performed to compare the different decision rules, using several criteria: mean tardiness, percent tardy, mean absolute deviation, mean queue time in the shop floor and in the system, and machine usage. We conclude that considering the four decisions simultaneously improve the job-shop performance, and planning both the input and the output when deciding to release a job, leads to an improvement of the operational performance measures. Copyright © 2012 Inderscience Enterprises Ltd.

2012

Hybrid heuristics for the single machine scheduling problem with quadratic earliness and tardiness costs

Authors
Singh, A; Valente, JMS; Moreira, MRA;

Publication
INTERNATIONAL JOURNAL OF MACHINE LEARNING AND CYBERNETICS

Abstract
In this paper we present three hybrid heuristics for the single machine scheduling problem with quadratic earliness and tardiness costs, and no machine idle time. Our heuristic is a combination of a steady-state genetic algorithm and three improvement procedures. The two computationally less expensive of these three improvement procedures are used inside the genetic algorithm to improve the schedule obtained after the application of genetic operators, whereas the more expensive one is used to improve the best solution returned by the genetic algorithm. We have compared our hybrid approaches against existing recovering beam search and genetic algorithms. The computational results show the effectiveness of our hybrid approaches. Indeed, our hybrid approaches outperformed the existing heuristics in terms of solution quality as well as running time.

2012

Integrated computational methods for traffic emissions route assessment

Authors
Gazis, A; Fontes, T; Bandeira, J; Pereira, S; Coelho, MC;

Publication
IWCTS 2012 - 5th ACM SIGSPATIAL International Workshop on Computational Transportation Science

Abstract
This paper focuses on the integration of multiple computational tools towards the objective of assessing emission impacts of different routes. Data from real life GPS tracks was integrated with traffic emission modelling for multiple pollutants (NOx, HC, CO and PM10) to investigate different routing strategies. The main conclusion is that different pollutants dictate different best routes. Hence, strategies for assigning relative weights to pollutants are devised in order to be able to select the best environment-friendly route. © 2012 ACM.

2012

Spatio-temporal prediction of atmospheric benzene (Part I)

Authors
Fontes, T; Barros, N;

Publication
ENVIRONMENTAL MONITORING AND ASSESSMENT

Abstract
Benzene is a carcinogenic and genotoxic pollutant which mainly affects the people health through the inhalation. Nevertheless, this pollutant is not frequently measured by air-quality networks. To solve this problem, some models have been published to estimate benzene concentrations in the atmosphere. However, the lack of measures makes difficult the application of complex models in order to get a detailed spatio-temporal analysis, namely in urban areas. In this work was developed a simple semi-empirical model to predict benzene concentrations based on the ratio of benzene and carbon monoxide concentrations in order to predict the concentrations of this pollutant in large areas and periods with lack of benzene measurements but with higher impact in the human health. The model was applied to an urban area, the Metropolitan Area of Oporto, for a period of 12 years (1995-2006). Monthly correlations between benzene and carbon monoxide concentrations at Custias air-quality station are significant (p = 0.01) and higher in winter (r (s) > 0.7) than in summer (0.3 > r (s) > 0.7). Estimate of the monthly ratio of the concentration of these two pollutants range between 199 and 305. The methodology validation shows good results (r (s) = 0.81) which allow, assuming the availability of carbon monoxide data, the use of this tool for areas with low benzene recorded data. The application of this methodology in the study area shows an annual average trend decrease of benzene concentrations during the study period, which may be linked to a general trend decrease of benzene emissions in European urban areas, including the study domain.

2012

Towards effective tourism and people alignment

Authors
Ferreira, L; Putnik, G; Cruz Cunha, MM; Castro, H;

Publication
Organizational Integration of Enterprise Systems and Resources: Advancements and Applications

Abstract
The new (e)commerce/(e)business paradigms forced enterprises to undertake important transformations and reorganizations. It happened with the web and will be repeated in the Cloud and social networks, following Eric Schmidt's (Google CEO) thoughts, "better thinking now on WWC - World Wide Computer, that is, what is behind u-commerce, ubiquity". The tourism is no more only a traditional commercial activity but ever more social- and information-oriented. The tourism services need to be effective to be aligned with tourist requirements. The globalization and easy access allows tourists to change their plans constantly. Dynamic services reconfiguration and resulting impact on their information systems need to be supported. The theme here presented explores new tourism services requirements as the ubiquity and dynamic reconfiguration, new brokering mechanisms, and reliable integration processes, and humanto-human synchronous collaboration allow the natural involvement of the tourist on the co-creation of his activity plan with other agents (humans). © 2012, IGI Global.

2012

A review of agile and lean manufacturing as issues in selected international and national research and development programs and roadmaps

Authors
Castro, H; Putnik, GD; Shah, V;

Publication
Learning Organization

Abstract
Purpose: The aim of this paper is to analyze international and national research and development (R&D) programs and roadmaps for the manufacturing sector, presenting how agile and lean manufacturing models are addressed in these programs. Design/methodology/approach: In this review, several manufacturing research and development programs and roadmaps - national programs from the USA and Canada, and international programs from the European Union and from one international organization - are reviewed. Findings: The major finding of this review is that the main concerns in agile manufacturing, as highlighted in these programs, are networks, supply chain and product/service customization, and lean manufacturing's inclination towards achieving better cost efficiency. Although the lean manufacturing approach has been considered in many past and present programs, analysis of the most recent programs shows a greater priority is given to the agile manufacturing approach. The path towards sustainable manufacturing is delineated by pro-active attitude and action towards customers. Research limitations/implications: The study analyzes two national R&D programs from the USA, one international program from the European Union, three international roadmaps from the European Union, one business plan from Canada and one international roadmap from the global organization Intelligent Manufacturing Systems. Practical implications: The findings of this paper are intended to help managers, researchers and practitioners from the manufacturing sector to enhance their understanding and define suitable strategy for their organizations' sustainability and identify suitable manufacturing path with respect to agile and lean philosophies. This study could also help academics in defining course curricula for students more coherent with the R&D policies and/or requirements towards sustainable manufacturing with respect to agile and lean philosophies. Originality/value: There are reviews comparing agile and lean manufacturing paradigms, but there are no reviews about how the two manufacturing concepts are addressed in manufacturing R&D programs and roadmaps. © Emerald Group Publishing Limited.

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