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Publicações

Publicações por LIAAD

2025

Optimizing job shop scheduling with speed-adjustable machines and peak power constraints: A mathematical model and heuristic solutions

Autores
Homayouni, SM; Fontes, DBMM;

Publicação
INTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH

Abstract
This paper addresses a job shop scheduling problem with peak power constraints, in which jobs can be processed once or multiple times on either all or a subset of the machines. The latter characteristic provides additional flexibility, nowadays present in many manufacturing systems. The problem is complicated by the need to determine both the operation sequence and starting time as well as the speed at which machines process each operation. Due to the adherence to renewable energy production and its intermittent nature, manufacturing companies need to adopt power-flexible production schedules. The proposed power control strategies, that is, adjusting processing speed and timing to reduce peak power requirements may impact production time (makespan) and energy consumption. Therefore, we propose a bi-objective approach that minimizes both objectives. A linear programming model is developed to provide a formal statement of the problem, which is solved to optimality for small-sized instances. We also proposed a multi-objective biased random key genetic algorithm framework that evolves several populations in parallel. Computational experiments provide decision and policymakers with insights into the implications of imposing or negotiating power consumption limits. Finally, the several trade-off solutions obtained show that as the power limit is lowered, the makespan increases at an increasing rate and a similar trend is observed in energy consumption but only for very small makespan values. Furthermore, peak power demand reductions of about 25% have a limited impact on the minimum makespan value (4-6% increase), while at the same time allowing for a small reduction in energy consumption.

2025

The Application of Machine Learning and Deep Learning with a Multi-Criteria Decision Analysis for Pedestrian Modeling: A Systematic Literature Review (1999-2023)

Autores
Reyes-Norambuena, P; Pinto, AA; Martínez, J; Yazdi, AK; Tan, Y;

Publicação
SUSTAINABILITY

Abstract
Among transportation researchers, pedestrian issues are highly significant, and various solutions have been proposed to address these challenges. These approaches include Multi-Criteria Decision Analysis (MCDA) and machine learning (ML) techniques, often categorized into two primary types. While previous studies have addressed diverse methods and transportation issues, this research integrates pedestrian modeling with MCDA and ML approaches. This paper examines how MCDA and ML can be combined to enhance decision-making in pedestrian dynamics. Drawing on a review of 1574 papers published from 1999 to 2023, this study identifies prevalent themes and methodologies in MCDA, ML, and pedestrian modeling. The MCDA methods are categorized into weighting and ranking techniques, with an emphasis on their application to complex transportation challenges involving both qualitative and quantitative criteria. The findings suggest that hybrid MCDA algorithms can effectively evaluate ML performance, addressing the limitations of traditional methods. By synthesizing the insights from the existing literature, this review outlines key methodologies and provides a roadmap for future research in integrating MCDA and ML in pedestrian dynamics. This research aims to deepen the understanding of how informed decision-making can enhance urban environments and improve pedestrian safety.

2025

Clustering and Classification of Compositional Data Using Distributions Defined on the Hypersphere

Autores
Figueiredo, A;

Publicação
Springer Proceedings in Mathematics and Statistics

Abstract
We propose an approach to cluster and classify compositional data. We transform the compositional data into directional data using the square root transformation. To cluster the compositional data, we apply the identification of a mixture of Watson distributions on the hypersphere and to classify the compositional data into predefined groups, we apply Bayes rules based on the Watson distribution to the directional data. We then compare our clustering results with those obtained in hierarchical clustering and in the K-means clustering using the log-ratio transformations of the data and compare our classification results with those obtained in linear discriminant analysis using log-ratio transformations of the data. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.

2025

Evaluating the Therapeutic Potential of Exercise in Hypoxia and Low-Carbohydrate, High-Fat Diet in Managing Hypertension in Elderly Type 2 Diabetes Patients: A Novel Intervention Approach

Autores
Kindlovits, R; Sousa, AC; Viana, JL; Milheiro, J; Oliveira, BMPM; Marques, F; Santos, A; Teixeira, VH;

Publicação
NUTRIENTS

Abstract
Background/Objectives: Type 2 diabetes mellitus (T2DM) is a chronic condition marked by hyperglycemia, which can affect metabolic, vascular, and hematological parameters. A low-carbohydrate, high-fat (LCHF) diet has been shown to improve glycemic control and blood pressure regulation. Exercise in hypoxia (EH) enhances insulin sensitivity, erythropoiesis, and angiogenesis. The combination of LCHF and EH may offer a promising strategy for managing T2DM and hypertension (HTN), although evidence remains limited. This study aimed to assess the effects of an eight-week normobaric EH intervention at 3000 m simulated altitude combined with an LCHF diet on hematological and lipid profiles, inflammation, and blood pressure in older patients with T2DM and HTN. Methods: Forty-two diabetic patients with HTN were randomly assigned to three groups: (1) control group (control diet + exercise in normoxia), (2) EH group (control diet + EH), and (3) intervention group (EH+LCHF) Baseline and eight-week measurements included systolic, diastolic, and mean blood pressure (SBP, DBP, MAP), hematological and lipid profiles, and inflammation biomarkers. Results: Blood pressure decreased after the intervention (p < 0.001), with no significant differences between groups (SBP: p = 0.151; DBP: p = 0.124; MAP: p = 0.18). No differences were observed in lipid profile or C-reactive protein levels (p > 0.05). Mean corpuscular hemoglobin (MCH) increased in the EH group (p = 0.027), while it decreased in the EH+LCHF group (p = 0.046). Conclusions: Adding hypoxia or restricting carbohydrates did not provide additional benefits on blood pressure in T2DM patients with HTN. Further elucidation of the mechanisms underlying hematological adaptations is imperative.

2025

Evaluating the Therapeutic Potential of Exercise in Hypoxia and Low-Carbohydrate High-Fat Diet in Managing Hypertension in Elderly Type 2 Diabetes Patients: A Novel Intervention Approach

Autores
Kindlovits, R; Sousa, AC; Viana, JL; Milheiro, J; Oliveira, BMPM; Marques, F; Santos, A; Teixeira, VH;

Publicação

Abstract
Type 2 diabetes mellitus (T2DM) is a chronic disease characterized by hyperglycemia, which could alter metabolic, vascular and hematological parameters. A low-carbohydrate, high-fat diet (LCHF) diet benefits glycemic and blood pressure control. In turn, exercise in hypoxia (EH) is known to improve insulin sensitivity, erythropoiesis and angiogenesis. LCHF combined with EH seem to be a potential therapeutic strategy for T2DM and hypertension (HTN), but evidence is still scarce. The aim of this study was to evaluate the effects of eight weeks of EH combined with a LCHF on hematological and lipid profiles, inflammation and blood pressure in older patients with T2DM and coexistent HTN. Diabetic patients with HTN (n=42) were randomly assigned to a (1) control group: control diet (high-carbohydrate and low-fat diet) + exercise in normoxia; (2) EH group: control diet + EH; (3) intervention group: LCHF + EH. Baseline and eight-week measurements included systolic, diastolic, and mean blood pressure (SBP, DBP, MAP, respectively), and hematological and lipid profiles and inflammation biomarkers. Blood pressure decreased after interventions (p&amp;lt;0.001), with no differences among groups (SBP: p=0.151; DBP: p=0.124 and MAP: p=0.18). There were no differences in lipid profile and C-reactive protein (p&amp;gt;0.05). Mean corpuscular hemoglobin (MCH) increased in the EH group (p=0.027), while MCH concentration decreased in the EH+LCHF group (p=0.046). In conclusion, there is no additional benefit in adding hypoxia to exercise or restricting carbohydrates, on blood pressure in patients with T2DM and coexisting HTN. Further elucidation of the mechanisms underlying hematological adaptations is imperative. Trial registration number: NCT05094505.

2025

Histopathological Imaging Dataset for Oral Cancer Analysis: A Study with a Data Leakage Warning

Autores
Nogueira, M; Gomes, E;

Publicação
Proceedings of the 18th International Joint Conference on Biomedical Engineering Systems and Technologies

Abstract

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