2011
Authors
Lovera, M; Novara, C; dos Santos, PL; Rivera, D;
Publication
IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY
Abstract
2011
Authors
Agra, A; Avelino, C; Cerveira, A; Delgado, A; Poss, M;
Publication
International Journal of Mathematical Modelling and Numerical Optimisation
Abstract
We consider a real production planning problem occurring in a glass container manufacturing company. The goal is to minimise the average stock level during a planning horizon of one year, maintaining customers satisfaction and keeping the production at its maximum rate. Besides the production capacity, the main constraints considered are related to the number of setup changes in machines, which is restricted in each factory. The main goal is to find the best balance between the number of setups and the average stock level. We propose a decomposition of the problem into two interrelated problems: a lot-sizing problem and a scheduling problem. For each problem we propose a mathematical model that can be solved using a commercial solver package. To be an efficient managerial tool, the method should provide quickly good solutions. Therefore we solve the lot-sizing problem through a relax-and-fix heuristic and discuss the results. Copyright © 2011 Inderscience Enterprises Ltd.
2011
Authors
Pedrosa, C; Oliveira, BMPM; Albuquerque, I; Simoes Pereira, C; Vaz de Almeida, MD; Correia, F;
Publication
EUROPEAN JOURNAL OF NUTRITION
Abstract
Excess weight may be related to the development of adverse cardiometabolic risk factors in children. The aim of this study was to evaluate the effect of a lifestyle intervention program (nutrition and exercise counseling) on anthropometric parameters and metabolic syndrome (MS) components in Portuguese overweight/obese children. A total of 83 overweight/obese children aged 7-9 years were assigned to a 1-year individual or group-based treatment (GT); 61 children (z-score BMI (zBMI): 1.93 +/- A 0.28; 27 boys and 34 girls) completed the program. Anthropometric and biochemical parameters were assessed at baseline, at 6 months and at 1 year. The overweight/obese children, compared to normal-weight ones, presented significantly higher blood pressure, total-cholesterol, total-cholesterol/high density lipoprotein cholesterol (HDL) ratio, triglycerides, Apolipoprotein B and C-reactive protein levels, while HDL and Apolipoprotein A-I were significantly lower. At baseline, the prevalence of MS was 16.4% in overweight/obese and 0% in normal-weight children. The number of components of MS was significantly higher in children with higher zBMI. Lifestyle intervention led to a significant improvement in zBMI, waist circumference/height ratio, HDL, triglycerides, Apolipoprotein A-I, and Apolipoprotein B levels. The prevalence of MS decreased to 14.8%. The GT intervention seems to be more successful, with a significant decrease in zBMI and an increase in HDL and a lower drop-out rate. Overweight/obese children have multiple risk factors associated with the MS. Lifestyle intervention, both individual and group-based treatment, led to an improvement in the degree of overweight/obesity and in MS components.
2011
Authors
Burroughs, NJ; Oliveira, BMPM; Pinto, AA; Ferreira, M;
Publication
MATHEMATICAL AND COMPUTER MODELLING
Abstract
The consequences of regulatory T cell (Treg) inhibition of interleukine 2 secretion are examined by mathematical modelling. We determine the analytic formula that describes the fine balance between Regulatory T cells and T cells at controlled and immune response equilibrium states. We demonstrate that cytokine dependent growth exhibits a quorum T cell population threshold that determines if immune responses develop on activation. We determine the analytic formulas of T cell proliferation thresholds that allow us to study the sensibility of the quorum growth thresholds controlling immune responses.
2011
Authors
Machado, EM; Oliveira, MAY; Baptista, JD;
Publication
SHO2011: INTERNATIONAL SYMPOSIUM ON OCCUPATIONAL SAFETY AND HYGIENE
Abstract
The motivation to perform this particular research comes from a need which we feel exists for further research in this area. It is necessary to answer a set of questions both empirical (observed over the years in the area of health and safety) and theoretical (following an analysis of the international literature) relative to the dimension of the problem of musculoskeletal injuries resulting from the exercise of the nursing profession in a hospital context. Research questions addressed include: 1) Are there complaints associated to the performing of nursing tasks? 2) How serious in terms of absolute numbers are musculoskeletal injuries? 3) What sort of influence does the environment (namely buildings) play, as well as technology / equipment, and work organization? Furthermore, 4) What should be present in the workplace but is not? After analyzing survey (of 168 active nurses in Portuguese hospitals) and interview data and having observed nurses at work, accompanying them in their day-to-day tasks, there is a global tendency to consider that, over the last twelve months of work, in a hospital context, nursing professionals have felt pain or musculoskeletal discomfort in a part of their bodies. Research results point also to more training and more adequate working spaces being needed in order to decrease musculoskeletal injuries amongst nurses. Furthermore, the more widespread usage of technological means which are lacking in some hospitals (such as beds with adjustable height, trapeze-type supporting bars attached above beds, patient transferring lifts and transferring belts) or in bad condition (such as wheels on beds, wheelchairs, and stretchers, which makes moving patients difficult) could also reveal itself to be an important aid, presenting itself as a solution to the problem discussed herein, on the one hand due to the number of injuries on the other due to the need for more professionals.
2011
Authors
Saraiva, JT; Heitor, H; Correia, N; Araujo, R;
Publication
2011 8th International Conference on the European Energy Market, EEM 11
Abstract
This paper addresses the provision of ancillary services in Portugal and Spain in the scope of the Common Iberian Electricity market. The paper reviews the definitions and the international practice regarding ancillary services with emphasis on primary, secondary and tertiary reserves and describes the procedures adopted by the Portuguese and Spanish TSO's to procure and allocate reserve levels. On the other hand, the paper discusses the models that can be used to enlarge the integration of the reserve markets, namely regarding tertiary reserve. Using data from 2009, the paper presents the results of the simulations that were performed for several situations including an ideal unlimited interconnection capacity, the existing interconnection capacity and an interconnection capacity increased by 300 MW. The results obtained indicate that the adoption of a common tertiary reserve list would ultimately be beneficial for the consumers since the cost of tertiary reserve would be reduced. However, a larger integration and cooperation between the two TSO's would be clearly required. © 2011 IEEE.
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