Publications

  • 2025
    Ahmed Yosreddin Samti, Ines Ben Jaafar, Issam Nouaouri, Patrick Hirsh

    A Novel NSGA-III-GKM++ Framework for Multi-Objective Cloud Resource Brokerage Optimization

    June 2025 Mathematics 13(13):2042, 2025

    Abstract

    Cloud resource brokerage is a fundamental challenge in cloud computing, requiring the efficient selection and allocation of services from multiple providers to optimize performance, sustainability, and cost-effectiveness. Traditional approaches often struggle with balancing conflicting objectives, such as minimizing the response time, reducing energy consumption, and maximizing broker profits. This paper presents NSGA-III-GKM++, an advanced multi-objective optimization model that integrates the NSGA-III evolutionary algorithm with an enhanced K-means++ clustering technique to improve the convergence speed, solution diversity, and computational efficiency. The proposed framework is extensively evaluated using Deb–Thiele–Laumanns–Zitzler (DTLZ) and Unconstrained Function (UF) benchmark problems and real-world cloud brokerage scenarios. Comparative analysis against NSGA-II, MOPSO, and NSGA-III-GKM demonstrates the superiority of NSGA-III-GKM++ in achieving high-quality tradeoffs between performance and cost. The results indicate a 20% reduction in the response time, 15% lower energy consumption, and a 25% increase in the broker’s profit, validating its effectiveness in real-world deployments. Statistical significance tests further confirm the robustness of the proposed model, particularly in terms of hypervolume and Inverted Generational Distance (IGD) metrics. By leveraging intelligent clustering and evolutionary computation, NSGA-III-GKM++ serves as a powerful decision support tool for cloud brokerage, facilitating optimal service selection while ensuring sustainability and economic feasibility.

    Zakia Zouaghia, Zahra Kodia, Lamjed Ben Said

    Smapf-hnna: a novel Stock Market Analysis and Prediction Framework using Hybrid Neural Network Architectures Across Major US Indices

    International Journal of Data Science and Analytics (2025): 1-37., 2025

    Abstract

    Financial markets exhibit high volatility due to various external factors, making stock price prediction a complex yet crucial task for investors and financial institutions. Accurate forecasting not only enhances decision making but also mitigates financial risks. This paper introduces SMAPF-HNNA, an advanced framework that integrates multiple neural network (NN) architectures for robust time-series analysis and stock price forecasting. The proposed approach leverages Convolutional Neural Networks (CNNs) for automatic feature extraction, followed by the application of diverse NN models, including Simple Recurrent Neural Networks (SRNNs), Long Short-Term Memory (LSTM), Bidirectional LSTM (BiLSTM), Gated Recurrent Units (GRU), Bidirectional GRU (BiGRU), and Multilayer Perceptron (MLP) for precise stock price prediction. The framework is rigorously evaluated on multiple benchmark datasets, including NYSE, S&P 500, NASDAQ, and SSE, through extensive training and testing phases. Experimental results demonstrate that the hybrid CNN-MLP model outperforms other architectures across all datasets, achieving exceptionally low error rates with five key regression metrics. The model yields mean squared error (MSE) values between 0.000031 and 0.000004, root mean squared error (RMSE) between 0.0020 and 0.0056, mean absolute error (MAE) between 0.0018 and 0.0042, mean absolute percentage error (MAPE) between 0.12% and 0.32%, and R-squared (R) values ranging from 0.9995 to 0.9999, while maintaining low computational complexity across datasets. These results highlight the potential of SMAPF-HNNA as a highly accurate and computationally efficient solution for stock market prediction, addressing the limitations of previous methods. The proposed framework offers valuable insights for researchers and practitioners, paving the way for more reliable financial market forecasting models.

    Zakia Zouaghia, Zahra Kodia, Lamjed Ben Said

    A novel approach for dynamic portfolio management integrating K-means clustering, mean-variance optimization, and reinforcement learning

    Knowledge and Information Systems, 1-73., 2025

    Abstract

    Effective portfolio management is crucial in today’s fast-moving and unpredictable financial landscape. This paper introduces a powerful and adaptive investment framework that fuses classical portfolio theory with cutting-edge artificial intelligence (AI) to optimize portfolio performance during volatile market conditions. Our methodology seamlessly integrates K-means clustering to identify asset groupings based on correlation structures of technical indicators, mean-variance optimization (MVO) to achieve an ideal risk-return trade-off, and advanced Machine Learning (ML) and reinforcement learning (RL) techniques to dynamically adjust asset allocations and simulate market behavior. The proposed framework is rigorously evaluated on historical stock data from 60 prominent stocks listed on NASDAQ, NYSE, and S&P 500 indices between 2021 and 2024, a period marked by significant economic shocks, global uncertainty, and structural market shifts. Our experimental results show that our framework consistently outperforms traditional strategies and recent state of the art models, achieving superior metrics including Sharpe ratio, Sortino ratio, annual return, maximum drawdown, and Calmar ratio. We also assess the computational efficiency of the approach, ensuring its feasibility for real-world deployment. This work demonstrates the transformative potential of AI-driven portfolio optimization in empowering investors to make smarter, faster, and more resilient financial decisions amid uncertainty.

    Amel ZIDI, Rayen Jemili, Issam Nouaouri, Ines Ben Jaafar

    Optimizing Emergency Department Patient Flow Forecasting: A Hybrid VAE-GRU Model

    11th International Conference on Control, Decision and Information Technologies, 2025

    Abstract

    Emergency departments (EDs) face increasing
    patient demand, leading to overcrowding and resource strain.
    Accurate forecasting of ED visits is critical for optimizing
    hospital operations and ensuring efficient resource allocation.
    This paper proposes a hybrid model combining Variational
    Autoencoder (VAE) and Gated Recurrent Unit (GRU) to enhance
    patient flow predictions. The VAE extracts meaningful
    latent features while handling missing data, whereas the GRU
    captures complex temporal dependencies, improving forecasting
    accuracy. Compared to traditional models such as LSTM,
    GRU, and 1D CNN, our hybrid VAE-GRU model demonstrates
    superior predictive performance. Experimental results, based
    on real-world hospital data, highlight the model’s effectiveness
    in reducing prediction errors and improving decision-making
    in dynamic ED environments. Additionally, we compare the
    proposed model with ARIMA-ML, emphasizing the tradeoffs
    between computational efficiency and prediction accuracy.
    The findings suggest that hybrid deep learning approaches
    can significantly enhance healthcare resource management,
    reducing patient waiting times and improving overall hospital
    efficiency.

    Amel ZIDI, Issam Nouaouri, Ines Ben Jaafar

    Improving Emergency Triage in Crisis Situations: A Hybrid GAN-Boosting Approach with Machine Learning

    Second Edition IEEE Afro-Mediterranean Conference on Artificial Intelligence 2025 IEEE AMCAI IEEE AMCAI 2025, 2025

    Abstract

    Emergency departments (EDs) must quickly assess
    and prioritize patients, especially during crises when demand

    exceeds capacity. Traditional triage methods, such as the Jump-
    START protocol for pediatric cases and the START (Simple

    Triage and Rapid Treatment) method for adults, are commonly
    used but may lack precision under high-pressure situations.
    This paper proposes a hybrid approach combining ensemble
    models—XGBoost, AdaBoost, and CatBoost—with synthetic data
    augmentation using Generative Adversarial Networks (GANs) to
    enhance triage accuracy for critically ill patients.
    Models were trained on real-world ED data, including vital
    signs, symptoms, medical history, and demographics. GANs
    generated synthetic critical cases to address class imbalance,
    improving model sensitivity to high-risk profiles.

    Results show that GAN-augmented models outperform base-
    line models, with CatBoost offering the best balance between

    accuracy and computational efficiency. This approach improves
    patient prioritization, reduces delays, and supports better clinical
    decision-making in resource-limited environments.
    Index Terms—Emergency Department (ED), Patient Triage,

    Machine Learning (ML), AdaBoost, XGBoost, CatBoost, Genera-
    tive Adversarial Networks (GANs), Urgency Classification, Crisis

    Situations.

    Boutheina Drira, Haykel Hamdi, Ines Ben Jaafar

    Hybrid Deep Learning Ensemble Models for Enhanced Financial Volatility Forecasting

    Second Edition IEEE Afro-Mediterranean Conference on Artificial Intelligence 2025 IEEE AMCAI IEEE AMCAI 2025, 2025

    Abstract

    this paper presents a novel ensemble
    methodology that integrates deep learning models to enhance
    the accuracy and robustness of financial volatility forecasts. By
    combining Convolutional Neural Networks (CNNs) and GRU
    networks, the proposed approach captures both spatial and
    temporal patterns in financial time series data. Empirical results
    demonstrate the superiority of this ensemble model over
    traditional forecasting methods in various financial markets.
    Keywords: Volatility Forecasting, Deep Learning, Ensemble
    Modeling, CNN, GRU, Financial Time Series

    Wassim Ayadi, Joseph Andria, Giacomo di Tollo, Gerarda Fattoruso

    Biclustering sustainable local tourism systems by the Tabu search optimization algorithm

    Quality & Quantity, 2025

    Abstract

    Tourism is nowadays fully acknowledged as a leading industry contributing to boost the economic development of a country. This growing recognition has led researchers and policy makers to increasingly focus their attention on all those concerns related to optimally detecting, promoting and supporting territorial areas with a high tourist vocation, i.e., Local Tourism Systems. In this work, we propose to apply the biclustering data mining technique to detect Local Tourism Systems. By means of a two-dimensional clustering approach, we pursue the objective of obtaining more in-depth and granular information than conventional clustering algorithms. To this end, we formulate the objective as an optimization problem, and we solve it by means of Tabu-search. The obtained results are very promising and outperform those provided by classic clustering approaches.

    Eya Achouri, Wassim Ayadi

    ColBic: A New Biclustering-Based Collaborative Filtering.

    21st International Conference on Artificial Intelligence Applications and Innovations (AIAI 2025) : 381-391, 2025

    Abstract

    Recommendation systems have become essential for filtering the vast amounts of information available on the Internet. Traditional collaborative filtering methods face challenges such as data sparsity and scalability issues. To address these limitations, we propose ColBic, a novel collaborative filtering approach based on biclustering and Iterative Local Search (ILS). Our method improves the accuracy of the recommendation by grouping users and items into dense biclusters and refining them through iterative optimization. Experimental results on the MovieLens-100K and MovieLens-1M datasets demonstrate that ColBic outperforms traditional collaborative filtering methods in terms of accuracy and coverage.

    Sofian Boutaib, Maha Elarbi, Slim Bechikh, Carlos A Coello Coello, Lamjed Ben Said

    Cross-Project Code Smell Detection as a Dynamic Optimization Problem: An Evolutionary Memetic Approach

    IEEE Congress on Evolutionary Computation (CEC), 2025

    Abstract

    Code smells signal poor software design that can prevent maintainability and scalability. Identifying code smells is difficult because of the large volume of code, considerable detection expenses, and the substantial effort needed for manual tagging. Although current techniques perform well in within-project situations, they frequently struggle to adapt to cross-project environments that have varying data distributions. In this paper, we introduce CLADES (Cross-project Learning and Adaptation for Detection of Code Smells), a hybrid evolutionary approach consisting of three main modules: Initialization, Evolution, and Adaptation. The first module generates an initial population of decision tree detectors using labeled within-project data and evaluates their quality through fitness functions based on structural code metrics. The evolution module applies genetic operators (selection, crossover, and mutation) to create new offspring solutions. To handle cross-project scenarios, the adaptation module employs a clustering-based instance selection technique that identifies representative instances from new projects, which are added to the dataset and used to repair the decision trees through simulated annealing. These locally refined decision trees are then evolved using a genetic algorithm, thus enabling continuous adaptation to new project instances. The resulting optimized decision tree detectors are then employed to predict labels for the new unlabeled project instances. We assess CLADES across five open-source projects and we show that it has a better performance with respect to baseline techniques in terms of weighted F1-score and AUC-PR metrics. These results emphasize its capacity to effectively adjust to different project environments, facilitating precise and scalable detection of code smells while minimizing the need for manual review, contributing to more robust and maintainable software systems.

    Maha Elarbi, Slim Bechikh, Carlos Artemio Coello Coello

    Adaptive Normal-Boundary Intersection Directions for Evolutionary Many-Objective Optimization with Complex Pareto Fronts

    In International Conference on Evolutionary Multi-Criterion Optimization (pp. 132-147). Singapore: Springer Nature Singapore., 2025

    Abstract

    Decomposition-based Many-Objective Evolutionary Algorithms (MaOEAs) usually adopt a set of pre-defined distributed weight vectors to guide the solutions towards the Pareto optimal Front (PF). However, when solving Many-objective Optimization Problems (MaOPs) with complex PFs, the effectiveness of MaOEAs with a fixed set of weight vectors may deteriorate which will lead to an imbalance between convergence and diversity of the solution set. To address this issue, we propose here an Adaptive Normal-Boundary Intersection Directions Decomposition-based Evolutionary Algorithm (ANBID-DEA), which adaptively updates the Normal-Boundary Intersection (NBI) directions used in MP-DEA. In our work, we assist the selection mechanism by progressively adjusting the NBI directions according to the distribution of the population to uniformly cover all the parts of the complex PFs (i.e., those that are disconnected, strongly convex, degenerate, etc.). Our proposed ANBID-DEA is compared with respect to five state-of-the-art MaOEAs on a variety of unconstrained benchmark problems with up to 15 objectives. Our results indicate that ANBID-DEA has a competitive performance on most of the considered MaOPs.