CEGI - Indexed Articles in Conferences

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    An agent-based simulation approach to the circular open dimension problem
    ( 2015) Ribeiro,JP ; Rossetti,RJF ; José Fernando Oliveira
    Cutting and packing problems generally address the cutting or packing of smaller items into a larger container object. Usually, the main methodologies used in the Circular Open Dimension Problem (CODP) are nonlinear programming methods or methods that combine different heuristics. The aim of this project is at devising and using an agent-based simulation approach to determine the length of the open rectangle in CODP; more specifically, we look into the Circular two-dimension Open Dimension Problem. Agents (circles, which can have different dimensions) were given a set of simple rules that allow them to be placed in the world (i.e. an open rectangle). These rules are inferred from the formal CODP formulation and from the behavior defined in the agents.
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    An algorithm for packing tubes and boxes
    ( 2015) João Pedro Pedroso ; Tavares,JN ; Leite,J
    In this paper we describe a method for packing tubes and boxes in containers. Each container is divided into parts (holders) which are allocated to subsets of objects. The method consists of a recursive procedure which, based on a predefined order for dealing with tubes and boxes, determines the dimensions and position of each holder. Characteristics of the objects to pack and rules limiting their placement make this problem unique. The method devised provides timely and practical solutions.
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    Application of collaborative information exchange in urban public transport: the Seamless Mobility solution
    ( 2016) Costa,PM ; Tânia Daniela Fontes ; Nunes,AA ; Marta Campos Ferreira ; Vera Lúcia Costa ; Teresa Galvão ; José Luís Borges ; João Falcão Cunha
    Contemporary urban transportation networks are facing challenges to address the growing needs of mobility, all the while improving their economic gains and environmental sustainability. Several studies demonstrate that competitive alternatives to individual private transport are able to address these challenges, such as public transportation services. Thus, the need for optimising their operational efficiency and offer user-centric service delivery arises, with a range of challenges related to the inherent complexity of urban transportation networks as well as the range of dynamic elements involved in such systems. An innovative approach to this problem leverages personal mobile devices in combination with collaborative exchange of information. In this study a system was developed to combine information provided by travellers with data from public transport operators. The result is a rich model of the transportation network that enables the distribution of information in a personalized way and in real-time: the Seamless Mobility solution. Large-scale and expensive infrastructures, such as existing ticketing systems, constitute a threat to such flexibility and traveller access to services. As a result, a distributed architecture was targeted with the goal of integrating personal mobile devices in the infrastructure, with benefits for travellers and transport operators. The proposed solution integrates a broad scope of challenges, including application of secure mobile payments methods, data aggregation from different components and distribution based on relevance techniques. With the implementation of this solution we expect to positively impact the way travellers and transport operators interact, and contribute towards mobility services that are more agile and adequate, taking into account that mobility patterns vary from person to person, seasonally, and even throughout a day. (C) 2016 The Authors. Published by Elsevier B.V.
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    Architecture for centralizing healthcare services
    ( 2015) Ferreira,D ; Rocha,T ; António Carvalho Brito
    Despite the technological advances, healthcare systems still face several issues. One of the most important is the lack of communication between systems or the communication process speed. If the information about a patient is not promptly shared in time between services, it may jeopardise the practicioner-pacient relationship. In a worse scenario, the system can even become a handicap and turn the Healthcare processes down into a state of total uselessness. A lot has been done in Portugal to enable the interconnection of external healthcare applications with the ones used in the National Health Service. In this article we present an architecture to facilitate this interconnection. Based on a REST architecture and HL7 communication standards, it connects two current solutions, one for melanoma and one for blood donors, with a central healthcare data repository of the National Healthcare Service. © 2015 AISTI.
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    Assessing contextual mood in public transport: A pilot study
    ( 2013) Costa,PM ; Pitt,J ; Teresa Galvão ; João Falcão Cunha
    In recent years, the technological developments in mobile and communication networks have paved the way for smart environments, whose final goal is to provide users with enhanced experiences. The measure of user experience satisfaction, or quality of experience, may be defined as an affective state in response to a service. Thus, an experiment was devised to explore the relationship between users' affective state and their context, for assessing quality of experience in urban public transport services. A pilot study, conducted to evaluate the feasibility and requirements of such an experiment is presented, leading to a large scale field study. © 2013 Authors.
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    Assessing Technical and Economic Efficiency of the Artisanal Dredge Fleet in the Portuguese West Coast
    ( 2015) Manuela Maria Oliveira ; Ana Camanho ; Gaspar,MB
    The bivalve dredge fleet is by far the most extensively studied fleet among the Portuguese artisanal segment. It is considered one of the most important artisanal fisheries, essentially due to the number of fishermen and vessels involved and to the high volume and value of the catches. The present study aimed to explore the efficiency of the dredge fleets that operated in the west coast of Portugal between 2006 and 2012. The methodology was based on the use of data envelopment analysis to assess vessels' efficiency. The inputs considered included the number of days at sea, a biomass stock indicator, and the characteristics of the vessels (power, length and tonnage). The annual fishing quota per vessel was also included in the model as a contextual factor. In the technical efficiency analysis, the outputs were defined by the weight of captures for three different bivalve species. Using data on the prices of each species in the wholesale market, revenue efficiency was also estimated to complement the technical efficiency analysis. The results allowed to gain insights concerning the performance of both Northwest and Southwest fleets, considering both technical and economic aspects of the fishery. It was also possible to identify the benchmark vessels, whose practices should be followed by the other vessels of the fleet.
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    The Assessment of Municipal Services: Environmental Efficiency of Buildings Construction
    ( 2016) Isabel Horta ; Ana Camanho ; Teresa Galvão ; Niza,S
    This paper develops an innovative methodology to assess municipal performance concerning the environmental efficiency of new buildings construction, focusing on the consumption of different types of materials. This study aims to support local governments in the definition of policies for improvements in service provision based on the results of a benchmarking study. The methodology developed includes two stages. The first step concerns the evaluation of municipal environmental efficiency using Data Envelopment Analysis and the identification of factors that may explain different levels of performance. The second step enables the classification of municipalities in terms of the efforts required to achieve environmental efficiency. For this purpose, we used clustering analysis, namely the k-means algorithm. To illustrate the methodology developed, we analyzed the data of the major materials used in the construction of new buildings (metals, non-metallic minerals, fossil fuels, and biomass) in the municipalities of Lisbon metropolitan area between 2003 and 2009. The study revealed that the environmental efficiency of new buildings construction varies considerably among municipalities, suggesting a high potential for performance improvement.
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    Assessment of performance and innovation of Portuguese construction companies
    ( 2011) Isabel Horta ; Jorge Moreira da Costa ; Ana Camanho
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    The Assessment of Performance of Educational Services: The Case of Portuguese Secondary Schools
    ( 2016) Portela,MCAS ; Ana Camanho
    This paper describes the assessment of performance of educational services recurring to benchmarking. We adopted two perspectives for the evaluation of secondary schools, aligned with the objectives of different stakeholders. In the society perspective schools are viewed as promoting students achievement ( ideally including not only academic results but also interpersonal capacities) given the students characteristics in terms of academic abilities and socio-economic backgrounds. In the educational authorities perspective schools are viewed as transforming a set of resources ( including students with given characteristics in terms of academic abilities and socioeconomic backgrounds and also school resources, such as teachers) into students achievement. The relative performance assessment was carried out using Data Envelopment Analysis models, followed by an exploratory analysis of contextual indicators that potentially affect schools' performance, in order to understand their impact on the educational process.
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    Building an extended ontological perspective on Service Science
    ( 2014) Dragoicea,M ; Borangiu,T ; João Falcão Cunha ; Oltean,VE ; José Faria ; Radulescu,S
    This paper presents an approach accounting for the classification of the main knowledge resources related to the new Science of Service. The main knowledge categories are defined as concepts integrated in an extended Service Science ontology. The ontology derived from several sources was captured using UML and Protégé, and then, through a RDF/OWL transformation, a semantically annotated wiki has been directly implemented offering an execution of the ontology together with implemented use cases. Further, a dedicated application was developed - the Service Science Knowledge Environment (SSKE) - in order to grant user access to different knowledge categories created along with the proposed ontology. The SSKE is a cloud based collaborative software service, aiming at providing co-created knowledge resources shared by academia, industry and government organizations. This application can be accessed through the Web (http://sske.cloud.upb.ro/) and it can be used for managing service related knowledge. © Springer International Publishing Switzerland 2014.
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    Cargo dynamic stability in the container loading problem -a physics simulation tool approach
    ( 2017) António Galrão Ramos ; João Tiago Jacob ; Justo,JF ; José Fernando Oliveira ; Rui Pedro Rodrigues ; António Miguel Gomes
    The container loading problem (CLP) is a real-world driven, combinatorial optimisation problem that addresses the maximisation of space usage in cargo transport units. The research conducted on this problem failed to fulfill the real needs of the transportation industry, owing to the inadequate representation of practical-relevant constraints. The dynamic stability of cargo is one of the most important practical constraints. It has been addressed in the literature in an over-simplified way which does not translate to real-world stability. This paper proposes a physics simulation tool based on a physics engine, which can be used to translate real-world stability into the CLP. To validate the tool, a set of benchmark tests is proposed and the results obtained with the physics simulation tool are compared to the state-of-the-art simulation engineering software Abaqus Unified FEA. Analytical calculations have been also conducted, and it was also possible to conclude that the tool proposed is a valid alternative. Copyright © 2017 Inderscience Enterprises Ltd.
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    Challenging user interaction in Public Transportation Spider Maps: a Cobweb solution for the city of Porto
    ( 2016) Maciel,F ; Teresa Galvão
    In Public Transportation systems, accurate representation of information has been key for users to take the more advantages of the services and fulfil their travel needs. The Spider Map is a particular schematic representation to illustrate all travel possibilities from a given geographical location. Recently the Spider Map interaction and generation process automation have been studied, although there are yet different possibilities to explore in the technological approach and interactive solution fields. This research proposes the Cobweb solution, dissecting the components of an Interactive Spider Map, focusing on the interactive dynamic potential, the ways to represent information, challenging the existing standard. An implementation of this solution is evaluated using carefully designed user tests to validate the design decisions, taking into consideration different interaction alternatives for each phase of the map generation. The results show improvements regarding the traditional alternative, with positive user response, valuing highly context awareness and information features.
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    Circle covering representation for nesting problems with continuous rotations
    ( 2014) Pedro Filipe Rocha ; Rui Pedro Rodrigues ; Gomes,AM ; Toledo,FMB ; Andretta,M
    This paper analyses distinct methods to represent a polygon through circle covering, which satisfy specific requirements, that impact primarily the feasibility and the quality of the layout of final solution. The trade-off between the quality of the polygonal representation and its derived number of circles is also discussed, showing the impact on the resolution of the problem, in terms of computational efficiency. The approach used to tackle the Nesting problem in strip packing uses a Non-Linear Programming model. Addressing these problems allows to tackle real world problems with continuous rotations. © IFAC.
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    Circle covering using medial axis
    ( 2013) Pedro Filipe Rocha ; Rui Pedro Rodrigues ; Toledo,FMB ; António Miguel Gomes
    A good representation of a simple polygon, with a desired degree of approximation and complexity, is critical in many applications. This paper presents a method to achieve a complete Circle Covering Representation of a simple polygon, through a topological skeleton, the Medial Axis. The aim is to produce an efficient circle representation of irregular pieces, while considering the approximation error and the resulting complexity, i.e. the number of circles. This will help to address limitations of current approaches to some problems, such as Irregular Placement problems, which will, in turn, provide a positive economic and environmental impact where similar problems arise. © 2013 IFAC.
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    Combining data analytics with layout improvement heuristics to improve libraries’ service quality
    ( 2017) Silva,DV ; Vera Miguéis
    Currently, many libraries, either academic or public, possess information systems to support their operations. Although libraries are becoming more aware of the potential of data analytics in supporting library management decisions, there is still a long way to go to take plenty advantage of the information collected. This paper proposes a prescriptive analytics solution to enhance the service provided by libraries, by optimizing libraries layout. The quantitative method introduced aims to identify layout configurations that minimize the time spent by clients in picking books from the library. A new multi-floor layout optimization algorithm is developed, based on the pairwise exchange method heuristic. A real data sample of approximately 66.000 loans, taken from the information system of a European Engineering School’s library, was analyzed and processed. The method proposed was used to improve the library’s current departments configuration, achieving an improvement of 13.2% in terms of walking distance to collect the books. The results corroborate the effectiveness of the method proposed and its potential in supporting library management decisions. © Springer International Publishing AG 2017.
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    Combining Supplier Selection and Production-Distribution Planning in Food Supply Chains
    ( 2014) Pedro Amorim ; Bernardo Almada-Lobo ; Barbosa Povoa,APFD ; Grossmann,IE
    This work addresses an integrated framework for deciding about the supplier selection in processed food supply chains that accounts for tactical production and distribution planning. We are especially concerned with the option of producing with local or mainstream raw materials. The contribution of this paper is two-fold. Firstly, it proposes a new multi-objective two-stage stochastic mixed-integer programming model for the supplier selection that maximizes the profit and minimizes the risk of a low customer service. Secondly, the main complexities of processed food supply chains management are considered: perishability of raw materials and final products, uncertainty at downstream and upstream parameters, and customer willingness to pay. Results indicate that dual sourcing is a strategy to be pursued across several scenarios. The multi-objective approach shows that a small decrease in the expected value of profit results in a significant increase in the customer service. Acknowledging the increase in customers willing to pay for local products is also fundamental.
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    A compact formulation for maximizing the expected number of transplants in kidney exchange programs
    ( 2015) Alvelos,F ; Xenia Klimentova ; Rais,A ; Ana Viana
    Kidney exchange programs (KEPs) allow the exchange of kidneys between incompatible donor-recipient pairs. Optimization approaches can help KEPs in defining which transplants should be made among all incompatible pairs according to some objective. The most common objective is to maximize the number of transplants. In this paper, we propose an integer programming model which addresses the objective of maximizing the expected number of transplants, given that there are equal probabilities of failure associated with vertices and arcs. The model is compact, i.e. has a polynomial number of decision variables and constraints, and therefore can be solved directly by a general purpose integer programming solver (e.g. Cplex).
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    A Compact Formulation for the Kidney Exchange Problem
    ( 2012) Abdur Rais ; Miguel Cosntantino ; Xenia Klimentova ; Ana Viana ; João Pedro Pedroso
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    Consistent Consolidation Strategies in Grocery Retail Distribution
    ( 2019) Sara Sofia Martins ; Pedro Amorim ; Bernardo Almada-Lobo ; 5964 ; 6061 ; 5428
    In the food retail sector, maintaining the food quality across the supply chain is of vital importance. The quality of the products is dependent on its storage and transportation conditions and this peculiarity increases the supply chain complexity relatively to other types of retailers. Actually, in this industry there are three types of food supply chains: frozen, chilled and ambient. Moreover, food retailers run different store formats, of different sizes, assortments and sales volume. In this study we research the trade-off between consolidating a range of products in order to perform direct deliveries to the stores versus performing separate delivery routes for products with different transportation requirements. A new consistency dimension is proposed regarding the periodicity that a consolidation strategy is implemented. The aim of this paper is to define a consolidation strategy for the delivery mode planning that allows to smooth the complexity of grocery retail operations. A three-step approach is proposed to tackle a real size problem in a case-study with a major Portuguese grocery retailer. By changing the consolidation strategy with a complete consistent plan the company could reach annual savings of around 4%. © 2019, Springer Nature Switzerland AG.
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    Decentralized Vs. Centralized Sequencing in a Complex Job-Shop Scheduling
    ( 2017) Afshin Mehrsai ; Gonçalo Reis Figueira ; Santos,N ; Pedro Amorim ; Bernardo Almada-Lobo
    Allocation of jobs to machines and subsequent sequencing each machine is known as job scheduling problem. Classically, both operations are done in a centralized and static/offline structure, considering some assumptions about the jobs and machining environment. Today, with the advent of Industry 4.0, the need to incorporate real-time data in the scheduling decision process is clear and facilitated. Recently, several studies have been conducted on the collection and application of distributed data in real-time of operations, e.g., job scheduling and control. In practice, pure distribution and decentralization is not yet fully realizable because of e.g., transformation complexity and classical resistance to change. This paper studies a combination of decentralized sequencing and central optimum allocation in a lithography job-shop problem. It compares the level of applicability of two decentralized algorithms against the central scheduling. The results show better relative performance of sequencing in stochastic cases. © IFIP International Federation for Information Processing 2017.