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Publicações

Publicações por CEGI

2013

Dynamic multi-interface services: An application to the design of a multimedia service

Autores
Teixeira, JG; Patricio, L; Huang, KH; Nobrega, L; Constantine, L; Fisk, RP;

Publicação
Proceedings - 2013 5th International Conference on Service Science and Innovation, ICSSI 2013

Abstract
The development and widespread market acceptance of recent technological devices, such as smart phones and tablets, poses new challenges and great opportunities for innovative service designs. In fact these devices no longer merely replicate the same functionalities in different contexts, they can also dynamically interact among themselves when in close proximity. Thus, this is a two-fold challenge for service designers, they must handle the additional points of contact between service providers and their customers independently, and also in combinations. In this paper we present the relevant concepts for designing multi-interface services, and also introduce the concept of dynamic service interfaces. We illustrate these dynamic service interfaces by presenting an application to the design of a new multimedia service. This service makes use of dynamic service interfaces to deliver an improved and innovative customer experience. © 2013 IEEE.

2013

Circle covering using medial axis

Autores
Rocha, P; Rodrigues, R; Toledo, FMB; Gomes, AM;

Publicação
IFAC Proceedings Volumes (IFAC-PapersOnline)

Abstract
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.

2013

Managing perishability in production-distribution planning: a discussion and review

Autores
Amorim, P; Meyr, H; Almeder, C; Almada Lobo, B;

Publicação
FLEXIBLE SERVICES AND MANUFACTURING JOURNAL

Abstract
Managing perishability may represent a remarkable problem in supply chain management of a varied set of industries. In fact, perishability can influence, for example, productivity or customer service and it may happen to occur in one or more processes throughout the supply chain. In this paper a review on planning models that handle perishability issues in production and distribution is conducted. The contribution of this paper is three-fold. First, a new framework for classifying perishability models based on multiple process features is presented. Second, it draws the community attention to the importance of managing perishability in many different industries' supply chains by showing its relevance and by reviewing the literature related to production and distribution planning. Finally, it points towards research opportunities so far not addressed by the research community in this challenging field.

2013

An operating theater planning decision support system

Autores
Gomes, C; Sperandio, F; Peles, A; Borges, J; Brito, AC; Almada Lobo, B;

Publicação
Information Systems and Technologies for Enhancing Health and Social Care

Abstract
The operating theater is the biggest hospital budget expenditure. The usage of surgery related resources and its intrinsic planning must be carefully devised in order to achieve better operational performance. However, from long to short term planning, the decision processes inherent to the operating theater are often the subject of empiricism. Moreover, the current hospital information systems available in Portuguese public hospitals lack a decision support system component, which could assist in achieving better planning solutions. This work reports the development of a centralized system for the operating theater planning to support decision-making tasks of surgeons, chief specialty managers, and hospital administration. Its main components concern surgery scheduling, operating theater's resource allocation and performance measurement. The enhancement of the planning processes, the increase of policy compliance, and the overall performance of the operating theater compared to the former methodologies are also discussed. © 2013, IGI Global.

2013

Risk Management in Production Planning of Perishable Goods

Autores
Amorim, P; Alem, D; Almada Lobo, B;

Publicação
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH

Abstract
In food supply chain planning, the trade-off between expected profit and risk is emphasized by the perishable nature of the goods that it has to handle. In particular, the risk of spoilage and the risk of revenue loss are substantial when stochastic parameters related to the demand, the consumer behavior, and the spoilage effect are considered. This paper aims to expose and handle this trade-off by developing risk-averse production planning models that incorporate financial risk measures. In particular, the performance of a risk-neutral attitude is compared to the performance of models taking into account the upper partial mean and the conditional value-at-risk. Insights from an illustrative example show the positive impact of the-risk-averse models in operational performance indicators, such as the amount of expired products. Furthermore, through an extensive computational experiment, the advantage of the conditional value-at-risk model is evidenced, as it is able to dominate the solutions from the upper partial mean for the spoilage performance indicator. These advantages are tightly related to a sustainable view of production planning, and they can be achieved at the expense of controlled losses in the expected profit.

2013

A hybrid VNS approach for the short-term production planning and scheduling: A case study in the pulp and paper industry

Autores
Figueira, G; Santos, MO; Almada Lobo, B;

Publicação
COMPUTERS & OPERATIONS RESEARCH

Abstract
Mathematical formulations for production planning are increasing complexity, in order to improve their realism. In short-term planning, the desirable level of detail is particularly high. Exact solvers fail to generate good quality solutions for those complex models on medium- and large-sized instances within feasible time. Motivated by a real-world case study in the pulp and paper industry, this paper provides an efficient solution method to tackle the short-term production planning and scheduling in an integrated mill. Decisions on the paper machine setup pattern and on the production rate of the pulp digester (which is constrained to a maximum variation) complicate the problem. The approach is built on top of a mixed integer programming (MIP) formulation derived from the multi-stage general lotsizing and scheduling problem. It combines a Variable Neighbourhood Search procedure which manages the setup-related variables, a specific heuristic to determine the digester's production speeds and an exact method to optimize the production and flow movement decisions. Different strategies are explored to speed-up the solution procedure and alternative variants of the algorithm are tested on instances based on real data from the case study. The algorithm is benchmarked against exact procedures.

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