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Publicações

2025

Data-Driven Charging Strategies to Mitigate EV Battery Degradation

Autores
Carvalhosa, S; Ferreira, JR; Araújo, RE;

Publicação
IEEE ACCESS

Abstract
Battery degradation remains a major challenge in electric vehicle (EV) adoption, directly affecting long-term performance, cost, and user satisfaction. This paper proposes a data-driven charging strategy that reduces battery wear while meeting the user's daily range needs. By integrating manufacturer guidelines, battery aging models, and thermal dynamics, the proposed optimization algorithm dynamically adjusts the charging current and timing to minimize stressors, such as high temperatures and prolonged high state of charge (SoC). The methodology is responsive to user inputs such as departure time and required driving range, enabling personalized charging behavior. Simulation results show that this approach can reduce battery degradation by up to 2.7% over a 30-day period compared to conventional charging habits, without compromising usability. The framework is designed for integration into Battery Management Systems (BMS), with applications for both private EV users and fleet operators. We address EV battery aging driven by high core temperature and prolonged high state of charge (SoC) during overnight/home charging. Given a user-specified departure time and required driving range, we schedule charging power over time to minimize predicted degradation exposure while still meeting the range requirement. The scheduler optimizes charging timing/current under SoC dynamics, thermal constraints, and charger/ BMS limits.

2025

Assessing the information security posture of online public services worldwide: Technical insights, trends, and policy implications?

Autores
Ribeiro, D; Fonte, V; Ramos, LF; Silva, M;

Publicação
GOVERNMENT INFORMATION QUARTERLY

Abstract
The fast global expansion of online public services has transformed how governments interact with citizens, offering convenience and efficiency. However, this digital transformation also introduces significant security risks, as sensitive data exchanged between users and service providers over public networks are exposed to cyber threats. Thus, ensuring the security and trustworthiness of these services is critical to the success of Electronic Government (EGOV) initiatives. This study evaluates the information security posture of 3068 public service platforms across all 193 UN Member States through non-intrusive assessments conducted in 2023 and 2024. The evaluation focuses on three key dimensions: (i) the adoption of secure end-to-end communication protocols, (ii) the trustworthiness of digital certificate chains, and (iii) the exposure of hosting servers to known vulnerabilities. The findings reveal that while some progress has been made in securing online public services, substantial gaps remain in the implementation of international security standards and best practices. Many platforms continue to rely on outdated cryptographic protocols, misconfigured certificates, and unpatched vulnerabilities, leaving citizens and services vulnerable to cyber threats due to weaknesses that malicious actors can easily and inconspicuously identify. These insights emphasize the need for effective implementation of more comprehensive cybersecurity policies, proactive security assessments, and improved regulatory compliance checks. Additionally, this work provides actionable guidance for governments and system administrators to enhance the security of EGOV infrastructures by addressing persistent vulnerabilities and adopting robust cybersecurity practices.

2025

Cherry-Picking in Time Series Forecasting: How to Select Datasets to Make Your Model Shine

Autores
Roque, L; Cerqueira, V; Soares, C; Torgo, L;

Publicação
THIRTY-NINTH AAAI CONFERENCE ON ARTIFICIAL INTELLIGENCE, AAAI-25, VOL 39 NO 19

Abstract
The importance of time series forecasting drives continuous research and the development of new approaches to tackle this problem. Typically, these methods are introduced through empirical studies that frequently claim superior accuracy for the proposed approaches. Nevertheless, concerns are rising about the reliability and generalizability of these results due to limitations in experimental setups. This paper addresses a critical limitation: the number and representativeness of the datasets used. We investigate the impact of dataset selection bias, particularly the practice of cherry-picking datasets, on the performance evaluation of forecasting methods. Through empirical analysis with a diverse set of benchmark datasets, our findings reveal that cherry-picking datasets can significantly distort the perceived performance of methods, often exaggerating their effectiveness. Furthermore, our results demonstrate that by selectively choosing just four datasets - what most studies report - 46% of methods could be deemed best in class, and 77% could rank within the top three. Additionally, recent deep learning-based approaches show high sensitivity to dataset selection, whereas classical methods exhibit greater robustness. Finally, our results indicate that, when empirically validating forecasting algorithms on a subset of the benchmarks, increasing the number of datasets tested from 3 to 6 reduces the risk of incorrectly identifying an algorithm as the best one by approximately 40%. Our study highlights the critical need for comprehensive evaluation frameworks that more accurately reflect real-world scenarios. Adopting such frameworks will ensure the development of robust and reliable forecasting methods.

2025

Local stability in kidney exchange programs

Autores
Baratto, M; Crama, Y; Pedroso, JP; Viana, A;

Publicação
EUROPEAN JOURNAL OF OPERATIONAL RESEARCH

Abstract
When each patient of a kidney exchange program has a preference ranking over its set of compatible donors, questions naturally arise surrounding the stability of the proposed exchanges. We extend recent work on stable exchanges by introducing and underlining the relevance of a new concept of locally stable, or L-stable, exchanges. We show that locally stable exchanges in a compatibility digraph are exactly the so-called local kernels (L-kernels) of an associated blocking digraph (whereas the stable exchanges are the kernels of the blocking digraph), and we prove that finding a nonempty L-kernel in an arbitrary digraph is NP-complete. Based on these insights, we propose several integer programming formulations for computing an L-stable exchange of maximum size. We conduct numerical experiments to assess the quality of our formulations and to compare the size of maximum L-stable exchanges with the size of maximum stable exchanges. It turns out that nonempty L-stable exchanges frequently exist in digraphs which do not have any stable exchange. All the above results and observations carry over when the concept of (locally) stable exchanges is extended to the concept of (locally) strongly stable exchanges.

2025

Comparative Evaluation of the Performance of Vegetable Insulating Oils in Power Transformers Against the Lightning Impulse Voltage

Autores
Cardoso, AFM; Laranjeira, MM; Silva, BMA; da Rocha Pinto Ferreira, JR; Nunes, MVA;

Publicação
2025 16th IEEE International Conference on Industry Applications, INDUSCON 2025 - Proceedings

Abstract
Mineral oil has long been the standard insulating fluid in power transformers due to its excellent dielectric and thermal properties. However, growing environmental and safety concerns have sparked interest in alternative, eco-friendly insulating fluids. Esters have emerged as promising candidates due to their high biodegradability, flame retardance, and lower ecological impact. This paper compares two such insulating fluids-a natural ester (Envirotemp FR3) and a synthetic ester (Midel 7131)-under the influence of lightning impulse voltages, representing a critical stress condition for transformer insulation. High voltage tests, including dielectric loss factor (delta tangent) measurements, were performed before and after applying standardized impulse sequences. Results indicate that both esters maintained dielectric performance within acceptable limits, with the synthetic ester demonstrating superior stability under impulse stress. The findings confirm the technical feasibility of ester-based insulating oils as viable and sustainable alternatives to mineral oil in power transformers, supporting broader environmental and operational safety goals in modern power systems. © 2025 IEEE.

2025

oCANada: A Generation-Based Fuzzer for ECUs over CAN

Autores
Santos, T; Grümer, P; Parsamehr, R; Pacheco, H;

Publicação
2025 IEEE VEHICULAR NETWORKING CONFERENCE, VNC

Abstract
Electronic Control Units are embedded devices that control various critical features of an automobile. Consequently, it is crucial to develop tools that enable penetration testers to identify security vulnerabilities within these ECUs as efficiently as possible. Fuzzing, a widely-used technique, can help uncover vulnerabilities in various types of applications. Fuzzing can then be applied to test ECUs through their communication protocols, the most common being the Controller Area Network (CAN). We present oCANada, a generation-based fuzzer which can be utilized in order to craft CAN messages for fuzzing. Many existing CAN fuzzers rely on simple mutation-based fuzzing, which involves randomly changing bits in the CAN payload. This paper introduces a novel generation-based fuzzing approach that leverages CAN database files (DBCs) in order to craft syntactically correct messages. oCANada also incorporates State-of-the-Art CAN reverse engineering techniques in order to enable syntax-aware fuzzing even when DBCs are not available. Additionally, this paper discusses test oracle techniques employed for fuzzing ECUs over CAN in both greybox and blackbox environments. Finally, we present our results while running the tool which we used two CANoe simulations, a Gateway ECU, and a modified version of the instrument cluster simulator ICSim. In these results, we also compare our fuzzer to the well-known CaringCaribou fuzzer.

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