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Publications

2023

Robust Sales forecasting Using Deep Learning with Static and Dynamic Covariates

Authors
Ramos, P; Oliveira, JM;

Publication
APPLIED SYSTEM INNOVATION

Abstract
Retailers must have accurate sales forecasts to efficiently and effectively operate their businesses and remain competitive in the marketplace. Global forecasting models like RNNs can be a powerful tool for forecasting in retail settings, where multiple time series are often interrelated and influenced by a variety of external factors. By including covariates in a forecasting model, we can often better capture the various factors that can influence sales in a retail setting. This can help improve the accuracy of our forecasts and enable better decision making for inventory management, purchasing, and other operational decisions. In this study, we investigate how the accuracy of global forecasting models is affected by the inclusion of different potential demand covariates. To ensure the significance of the study's findings, we used the M5 forecasting competition's openly accessible and well-established dataset. The results obtained from DeepAR models trained on different combinations of features indicate that the inclusion of time-, event-, and ID-related features consistently enhances the forecast accuracy. The optimal performance is attained when all these covariates are employed together, leading to a 1.8% improvement in RMSSE and a 6.5% improvement in MASE compared to the baseline model without features. It is noteworthy that all DeepAR models, both with and without covariates, exhibit a significantly superior forecasting performance in comparison to the seasonal naive benchmark.

2023

Tools for Refactoring to Microservices: A Preliminary Usability Report

Authors
Fritzsch, J; Correia, FF; Bogner, J; Wagner, S;

Publication
CoRR

Abstract
While Microservices are a preferred choice for modern cloud-based applications, the migration and architectural refactoring of existing legacy systems is still a major challenge in industry. To address this, academia has proposed many strategies and approaches that aim to automate the process of decomposing a monolith into functional units. In this study, we review existing migration approaches regarding techniques used and tool support. From 91 publications, we extracted 22 tools, 7 of which address service decomposition. To assess them from an end-user perspective, we investigated their underlying techniques, installation, documentation, usability and support. For 5 of them, we generated service cuts using reference applications. The results of our preliminary work suggest that the inspected tools pursue promising concepts, but lack maturity and generalizability for reliable use by industry.

2023

The role of novel clinical digital tools in the screening or diagnosis of Obstructive Sleep Apnea – A systematic review (Preprint)

Authors
Duarte, M; Pereira-Rodrigues, P; Ferreira-Santos, D;

Publication

Abstract
BACKGROUND

Clinical digital tools are an up-and-coming new technology that can be used in the screening or diagnosis of obstructive sleep apnea (OSA) patients, notwithstanding the crucial role of polysomnography (PSG) – the gold standard.

OBJECTIVE

The aim of our study was to identify, gather, and analyze existing digital tools and smartphone-based health platforms that are being used for this disease’s screening or diagnosis in the adult population.

METHODS

We performed a comprehensive literature search in MEDLINE, Scopus, and Web of Science databases for studies evaluating the validity of digital tools in OSA screening or diagnosis until November 2022. The risk of bias was assessed using JBI Critical Appraisal Tool for Diagnostic Test Accuracy Studies. Sensitivity, specificity, and area under the receiver-operating curve (AUC) were used as discrimination measures.

RESULTS

We retrieved 1714 articles, 41 of which were included. We found 7 smartphone-based tools, 10 wearables, 11 bed/mattress sensors, 5 nasal airflow devices, and 8 other sensors that did not fit the previous categories. Only 8 (20%) studies performed external validation of their developed tool. Of those, the highest reported values for AUC, sensitivity, and specificity were 0.99, 96%, and 92%, respectively, for a clinical cutoff of apnea-hypopnea index (AHI) = 30 and correspond to a non-contact audio recorder that records sleep sounds, which are then analyzed by a deep learning technique that automatically detects sleep apnea events, calculates the AHI, and identifies OSA. Looking at the studies that only internally validated their models, the work that reported the highest accuracy measures showed AUC, sensitivity, and specificity values of 1.00, 100%, and 96%, respectively, for a clinical cutoff AHI = 30. It uses the Sonomat – a foam mattress that, aside from recording breath sounds, has pressure sensors that generate voltage when deformed, thus detecting respiratory movements, and using it to classify OSA events.

CONCLUSIONS

These clinical tools presented promising results, showing high discrimination measures (best results reaching AUC > 0.99). However, there is still a need for quality studies, comparing the developed tools with the gold standard and validating them in external populations and other environments before they can be used in a clinical setting.

CLINICALTRIAL

This systematic review was registered in PROSPERO under reference CRD42023387748.

2023

A new Matrix Form Genetic Encoding for Balanced, Compact and Connected Sectorization through NSGA-II

Authors
Ferreira, JS; Rodrigues, AM; Ozturk, EG;

Publication
International Journal of Multicriteria Decision Making

Abstract

2023

Nutritional Status among Portuguese and Turkish Older Adults Living in the Community: Relationships with Sociodemographic, Health and Anthropometric Characteristics

Authors
Ozturk, ME; Poinhos, R; Afonso, C; Ayhan, NY; de Almeida, MDV; Oliveira, BMPM;

Publication
NUTRIENTS

Abstract
Malnutrition is widespread among older adults, and its determinants may differ between countries. We compared Portuguese and Turkish non-institutionalized older adults regarding nutritional status, sociodemographic, health and anthropometric characteristics and studied the relationships between nutritional status and those characteristics. This cross-sectional study analyzed data from 430 Portuguese and 162 Turkish non-institutionalized older adults regarding sociodemographics, health conditions, the Mini-Nutritional Assessment (MNA-FF) and anthropometry. Turkish older adults were more likely to be malnourished or at risk of malnutrition and had lower average BMI but a higher calf circumference. A higher proportion of the Portuguese sample had tooth loss, diabetes, hypertension, oncologic diseases, kidney diseases, osteoarticular problems or eye problems, while less had anemia. A better nutritional status (higher MNA-FF score) was found among the Portuguese, males, people using dentures, those without tooth loss, hypertension, cardiovascular diseases, anemia or oncological diseases and was related to younger age, higher BMI and a higher calf circumference. Malnutrition and its risk were higher among older adults from Turkey, despite Portuguese older adults presenting a higher prevalence of chronic diseases. Being female, older age, tooth loss, hypertension, anemia, CVD or oncological disorders and having a lower BMI or CC were associated with higher rates of malnutrition among older adults from Portugal and Turkey.

2023

Stochastic crowd shipping last-mile delivery with correlated marginals and probabilistic constraints

Authors
Silva, M; Pedroso, JP; Viana, A;

Publication
EUROPEAN JOURNAL OF OPERATIONAL RESEARCH

Abstract
In this work, we study last-mile delivery with the option of crowd shipping. A company uses occasional drivers to complement its fleet in the activity of delivering products to its customers. We model it as a variant of the stochastic capacitated vehicle routing problem. Our approach is data-driven, where not only customer orders but also the availability of occasional drivers are uncertain. It is assumed that marginal distributions of the uncertainty vector are known, but the joint distribution is difficult to estimate. We optimize considering a worst-case joint distribution and model with a strategic planning perspective, where we calculate an optimal a priori solution before the uncertainty is revealed. A limit on the infea-sibility of the routes due to the capacity is imposed using probabilistic constraints. We propose an extended formulation for the problem using column-dependent rows and implement a branch-price-and-cut algorithm to solve it. We also develop a heuristic approximation to cope with larger instances of the problem. Through computational experiments, we analyze the solution and performance of the implemented algorithms.

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