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31,377 Article Results

Heart disease prediction through feature optimization, ensembles, and threshold calibration

10.11591/ijece.v16i5.pp2836-2846
Mehdi Mostofi , Touraj BaniRostam
Early detection of cardiovascular disease is critical for reducing mortality and enabling timely clinical intervention. While machine learning models have been widely applied to heart disease prediction, many studies prioritize overall accuracy rather than sensitivity, which is essential in medical screening tasks. This study proposes a structured multi-stage optimization framework that integrates feature optimization, ensemble model tuning, and recall-oriented decision-threshold calibration within a unified pipeline. Feature selection was performed using RFECV and importance-based methods to identify an optimal subset of 14 predictors, and ensemble classifiers including Random Forest, Extra Trees, and XGBoost were refined through hyperparameter tuning using RandomizedSearchCV. To prioritize sensitivity, the classification threshold was calibrated from 0.5 to 0.3. In the calibrated evaluation split, recall increased to 0.961 while maintaining strong discriminative performance (AUC ≈ 0.93). To assess robustness, stratified cross-validation and bootstrap resampling were conducted; cross-validation demonstrated stable recall performance around 0.88–0.89 across models, and bootstrap analysis yielded a mean recall of 0.902 (95% CI: 0.842–0.959), confirming that the recall-oriented optimization remains statistically reliable. McNemar’s test further indicated no statistically significant performance differences among the ensemble models. These findings demonstrate that integrating feature selection, ensemble learning, and threshold calibration can improve heart disease detection while maintaining predictive stability, providing a clinically aligned machine learning framework for cardiovascular risk assessment.
Volume: 16
Issue: 5
Page: 2836-2846
Publish at: 2026-10-01

Development of a T-instrument for soil resistivity measurement in agricultural applications

10.12928/telkomnika.v24i5.27943
Tedy; Institut Teknologi Bandung Setiawan , Satria; Institut Teknologi Bandung Bijaksana , Ulvienin; Institut Teknologi Bandung Harlianti
Geoelectric measurements are widely applied in natural resource exploration and groundwater studies. In this work, a prototype resistivity meter, referred to as the T-instrument, was developed for soil resistivity measurements in agricultural applications. The system is designed with an emphasis on portability, ease of operation, and field applicability. Measurements were conducted using the Wenner electrode configuration, and system performance was evaluated through comparison with a commercial resistivity meter (OYO McOhm). The results show a strong correlation coefficient of 0.96 between the two instruments, indicating good agreement. The instrument performs reliably within typical agricultural soil resistivity ranges and targets shallow soil depths relevant to crop root zones. However, further refinement is required to improve performance under high-resistivity conditions and optimize power efficiency.
Volume: 24
Issue: 5
Page: 1745-1754
Publish at: 2026-10-01

Low-cost educational prototype for IoT-based PV energy monitoring and MPPT control

10.11591/ijece.v16i5.pp2282-2293
Abdelmalek Mimouni , Youssef Chahet , Aumeur El Amrani , Mohamed Azeroual , Mohamed El Amraoui , Lahcen Bejjit
This paper presents a low-cost embedded platform integrating photovoltaic (PV) energy monitoring, maximum power point tracking (MPPT), and Internet of Things (IoT) communication for real-time control and performance evaluation. The proposed system is built around an ESP32 microcontroller with dual INA219 sensors and a custom-designed DC–DC boost converter operating at 20 kHz. Two MPPT strategies, perturb and observe (P&O) and fuzzy logic control (FLC), are implemented and experimentally compared under identical outdoor conditions. Experimental results obtained under natural irradiance demonstrate that the FLC approach achieves faster convergence and reduced steady-state oscillations compared to P&O. Specifically, FLC improves tracking efficiency from 82.5% to 84%, reduces duty cycle ripple, and increases average extracted power by approximately 1.5%. The system also enables real-time acquisition of I–V and P–V characteristics through duty-cycle sweeping. The proposed architecture integrates sensing, control, and IoT telemetry using MQTT and a ThingsBoard dashboard, enabling continuous monitoring with negligible communication latency relative to the MPPT update period. This work contributes a reproducible, low-cost testbed that bridges embedded control, power electronics, and IoT-based monitoring, with potential applications in both education and rapid prototyping of smart PV systems.
Volume: 16
Issue: 5
Page: 2282-2293
Publish at: 2026-10-01

Modeling and performance analysis of batteries in PV systems

10.11591/ijece.v16i5.pp2294-2303
Abdelfettah Boussaid , Hadjer Bounechba , Seif El-Islam Chelli , Salah Hammoudi
This research paper comprehensively examines photovoltaic batteries, essential elements of sustainable solar energy systems. This research includes a pre- cise mathematical model development to represent behavior and performance of these batteries, in order to better understand the storage and use of electri- cal energy generated by solar panels. In addition, a complete simulation was carried out to evaluate the performance of these models under various operating conditions, thus contributing to improve our understanding on various factors that influence batteries efficiency in real situations. In the field of battery man- agement, their performances were examined, such as charging and discharging mode as well as continuous monitoring of the battery status. The objective is to strengthen the use efficiency of solar energy and improve its sustainability, thus contributing to achieving the global sustainability goals and reducing harmful emissions associated with traditional energies.
Volume: 16
Issue: 5
Page: 2294-2303
Publish at: 2026-10-01

Role model identity contract enforcement as a structural determinant of identity drift suppression in autonomous large language model agents

10.11591/ijece.v16i5.pp2795-2805
Sahana B. , Charithra H. S. , Arshitha S. , Chandrakala Chandrakala , Neethu B. Krishna , Soumya Prasada , Bhanupriya P. , Aryaman Tiwary
Autonomous agents powered by large language models (LLMs) are deployed widely across finance, healthcare, legal review, and customer support. Each deployment assumes that an agent will remain within its assigned role—an assumption that adversarial users routinely challenge through identity drift attacks. This work asks whether placing enforcement logic outside the model, rather than embedding rules in the system prompt, is the primary factor governing drift suppression. We designed RMIC-Guard: a framework where a cryptographically sealed Role-Model Identity Contract (RMIC) is checked by a dual-pass middle ware engine on every planned tool call before execution proceeds. The engine runs a deterministic hard-rule pass followed by a semantic Intent Drift Score (IDS) computed from seven independent embedding-based signals. Experiments across four LLMs (claude-sonnet-4-6, claude-haiku-4-5, llama-3.3-70b-versatile, llama-3.1-8b-instant), four agent roles, and 5,212 API calls show that external enforcement reaches DSR 0.952–1.000, whereas the best prompt-only condition achieves only DSR 0.391. Ablation confirms the dual-pass architecture is necessary: neither pass alone achieves acceptable joint drift-suppression and false-positive performance. All code, contracts, and prompt data are released openly.
Volume: 16
Issue: 5
Page: 2795-2805
Publish at: 2026-10-01

Solid oxide fuel cells as next‑generation high‑efficiency alternatives to combined cycle gas turbines

10.12928/telkomnika.v24i5.27887
Ignatius; Politeknik Negeri Bandung Riyadi Mardiyanto , Handrea; Politeknik Negeri Bandung Bernando Tambunan , Haryadi; Politeknik Negeri Bandung Haryadi , Lina; Politeknik Negeri Bandung Troskialina , Sri; Politeknik Negeri Bandung Paryanto Mursid , Yusuf; Politeknik Negeri Bandung Sofyan , Lidya; Politeknik Negeri Bandung Elizabeth
This study provides a direct thermodynamic comparison between a combined cycle gas turbine (CCGT) and a solid oxide fuel cell (SOFC) system, each designed for approximately 450 MW gross output. The benchmark CCGT, based on Siemens STG5‑4000F and SST5‑5000 units, achieved 61% gross efficiency under baseline conditions, with moderate sensitivity to fuel composition. In contrast, the SOFC system, modeled with an active cell area of 250,000 m², demonstrated superior performance, reaching nearly 70% gross efficiency and exceeding 63% net efficiency, while requiring lower fuel input (18.5 kg/s versus 19.5 kg/s for CCGT). Efficiency trends highlight fundamental differences: CCGT shows incremental gains with increased fuel flow but remains below 57% net efficiency, whereas SOFC sustains higher values despite greater sensitivity to input variations. These findings emphasize SOFC’s potential as a next‑generation utility‑scale power technology, offering higher efficiency and reduced fuel demand, while acknowledging challenges in scalability, durability, and cost that must be addressed for practical deployment.
Volume: 24
Issue: 5
Page: 1805-1815
Publish at: 2026-10-01

Per-channel margin and nonlinear asymmetry in an eight-channel optical distribution network

10.11591/ijece.v16i5.pp2559-2574
Mohammed Kareem Al-Swaiedi , Ahmed Ali Skaiky
The physical layer of a wavelength-division-multiplexed optical distribution network for smart-city Internet-of-Things access is almost always reported from a single simulation run, which says nothing about its stability. This paper characterized an eight-channel C-band link over 25 km of standard single-mode fibre, modelled in OptiSystem, across thirty independent replications yielding 240 per-channel Q-factor observations. Every channel cleared the Q ≥ 6 threshold in every replication, with a system mean of 8.66, a per-channel 95% confidence interval never wider than 0.46, and a worst realization of 6.64 on the weakest channel, so the link held a stable margin rather than crossing the boundary between runs. The per-channel Q-factors followed a U-shape across the wavelength grid with its minimum at the centre, and a short-reach reference at 1 km showed that two thirds of the edge-to-interior asymmetry was established within the first kilometre. A launch-power sweep placed the usable ceiling between 10 and 13 dBm. A control experiment with the fibre nonlinearity disabled collapsed the edge-to-interior ratio from 1.354 to 1.038, establishing that 89% of the asymmetry was nonlinear in origin, while a four-wave-mixing coherence length of 0.74 km against the 25 km span identified cross-phase modulation as the mechanism.
Volume: 16
Issue: 5
Page: 2559-2574
Publish at: 2026-10-01

An artificial intelligence-based stacking ensemble framework for smart irrigation pump control using IoT sensor data

10.11591/ijece.v16i5.pp2652-2663
Sarra Gourari , Wafa Difallah , Belkacem Draoui
Efficient water management is essential for sustainable agricultural production, particularly in arid and semi-arid regions where water resources are limited. Machine-learning-based irrigation systems can support automated pump-operation decisions using environmental and soil-related sensor data. However, most previous studies have focused on individual machine-learning models, while the application of stacked ensembles to binary irrigation pump-status prediction remains relatively limited. This study proposes a stacking-based framework for predicting irrigation pump operation in an ON/OFF classification setting. The framework uses environmental and soil-related variables, including soil moisture, temperature, humidity, and a numerical time-related feature. Random forest (RF), extreme gradient boosting (XGBoost), and multilayer perceptron models were trained as base learners, and their out-of-fold (OOF) predictions were combined using a logistic-regression meta-learner. The models were evaluated on a held-out test set using accuracy, precision, recall, specificity, and F1-score. The individual models achieved accuracies ranging from 97.34% to 99.95%, with XGBoost providing the best individual performance. The proposed stacking ensemble achieved 99.97% accuracy, 99.94% precision, 100.00% recall, 99.94% specificity, and a 99.97% F1-score. Compared with XGBoost, the ensemble further refined predictive performance, improving accuracy by 0.02 percentage points and F1-score by 0.01 percentage points while achieving complete elimination of false negatives (100.00% recall). These results demonstrate the potential of stacked ensemble learning to improve binary pump-operation prediction and support data-driven irrigation management in water-limited environments.
Volume: 16
Issue: 5
Page: 2652-2663
Publish at: 2026-10-01

An intelligent artificial intelligence framework for business insight generation from streaming data

10.11591/ijai.v15.i5.pp4071-4080
Benymol Jose , Sajimon Abraham , Nikitha Sajith
Big data analytics helps organizations leverage their data to uncover new opportunities, leading to smarter decisions, more efficient operations, and ultimately higher profits. Effective use of big data and creating important predictive models make it more straightforward for a business to realize what the consumer likes and what he or she does not. This will enable the business to propose better offers and administrations with their items when contrasted to its competitors. In this paper, the authors suggest the use of a big data analytics platform combined with natural language processing (NLP) techniques to do the intelligent processing of unstructured streaming data. A new method utilizing Apache Spark pipelining is proposed to achieve predictive analytics for unstructured data streams. With this predictive model, mining of the unstructured streaming data can be done and intelligent predictions are made possible in real time using artificial intelligence techniques.
Volume: 15
Issue: 5
Page: 4071-4080
Publish at: 2026-10-01

Hybrid model for driver drowsiness prediction using neuro-fuzzy and random forest

10.11591/ijai.v15.i5.pp4304-4314
Mouhcine Lakhloufi , El Mehdi Mellouli
In this research, a new hybrid model designed was introduced to identify driver drowsiness by integrating an adaptive neuro-fuzzy inference system (ANFIS) with the random forest (RF) method. Driver drowsiness is one of the major risk factors for road accidents, and timely, accurate identification of it is vital for improving traffic safety. The main emphasis of our work is on the combination of ANFIS with RF. ANFIS uses fuzzy logic to represent intricate systems with uncertainties and non-linear relationships, on the other hand, RF offers powerful classification by its ensemble learning technique, performing well in high-dimensional feature spaces. This combination capitalizes on each model's strengths: ANFIS for its dynamic responding to uncertain data and RF for its high classification accuracy, robustness, and resistance to overfitting. The results from the different experiments confirmed that the hybrid ANFIS-RF outperformed its components considerably. It was able to return an enhancement in accuracy by 2.70% compared to ANFIS, and 0.16% compared to RF, while at the same time, dropping the mean squared error (MSE) by 33.40% compared to ANFIS and 2.85% compared to RF. Knowing that RF is already better than other traditional machine learning methods in classification, these results emphasize its major role in the effectiveness of the hybrid model.
Volume: 15
Issue: 5
Page: 4304-4314
Publish at: 2026-10-01

Beamforming design for interference cancellation in fifth generation new radio system

10.12928/telkomnika.v24i5.27664
Heba; Damascus University Shafeik Kashour , Abdelrazak; Damascus University Badawieh , Ali; Tartous University Ahmad , Mohammad; Higher Institute for Applied Science and Technology (HIAST) Rizk Assaf
This study proposes a hybrid beamforming (HBF) architecture for interference mitigation design aimed at improving interference cancellation in fifth-generation new radio (5G-NR) systems. The proposed architecture employs interference suppression at two processing level: the linear eigen zero forcing (EZF) method is applied at the base station (BS) to mitigate inter-user interference (IUI), while the nonlinear successive interference cancellation (SIC) is implemented at each user terminal to cancel intra-user interference. Although EZF is linear, meaning it doesn’t require iterative or cumulative operations, its operations are complex and rely on matrix inversion. On the other hand, SIC is a non-linear algorithm, meaning it requires many sequential iterative operations, which increases the probability of cumulative errors. Therefore, using EZF as the first stage makes the signals to be processed in SIC less overlapping, thus reducing cumulative errors, especially under varying channel conditions. The single to interference and noise ratio (SINR) reached a value of 11.9 dB. This is based on the simulation scenarios that were tested. and a channel quality indicator (CQI) value of 10. Moreover, the proposed scheme provides a spectral efficiency of 36 bit/s/Hz at 100 MHz bandwidth and -20 dB signal-to-noise ratio (SNR), achieving performance approaches the performance of a fully digital interference-free system under the considered simulation conditions. while maintaining practical computational complexity.
Volume: 24
Issue: 5
Page: 1469-1479
Publish at: 2026-10-01

Contour-guided convexity defect geometry for precise ROI extraction in dorsal hand vein recognition

10.11591/ijece.v16i5.pp2622-2640
Habib Kadem , Merah Mostefa
Dorsal hand vein biometrics depend strongly on accurate region-of-interest (ROI) extraction, yet conventional convexity-defect-based methods remain vulnerable to contour noise, skin texture, and shadow-induced artifacts. This paper introduces contour-guided convexity defect geometry (CG-CDG), a geometry-driven ROI extraction framework in which a candidate convexity defect is accepted as an anatomical valley only if it jointly satisfies two independent criteria: chord-contour topological consistency, ensuring anatomical relevance, and a minimum enclosed-area threshold, ensuring physical plausibility. Unlike prior convexity-defect-based methods, which accept a candidate valley on the basis of a single depth- or angle-based criterion evaluated in isolation, CG-CDG applies this joint plausibility test before defining the region of interest, a square ROI centered on the hand centroid and aligned with the dominant valley orientation. Experiments on a public dorsal hand vein database of 1,024 images from 138 subjects show that, combined with HOG descriptors and City Block distance, CG-CDG achieves an equal error rate (EER) of 0.0266, with a 95% bootstrap confidence interval of [0.0241, 0.0289] over the matching scores (B = 1,000 resamples), the narrowest interval among the four ROI extraction methods compared under the primary evaluation setting. A post-hoc Wilcoxon signed-rank test with Bonferroni correction confirms that this improvement is statistically significant over all competing methods (p < 0.001). On this dataset, geometric validation substantially reduces intra-class variance and yields statistically validated performance without requiring any training data, making CG-CDG a strong candidate both as a standalone, training-free biometric solution and as an anatomically grounded preprocessing stage for hybrid deep-learning pipelines.
Volume: 16
Issue: 5
Page: 2622-2640
Publish at: 2026-10-01

Design science research in developing a religious chatbot based on Bulugh al-Maram

10.11591/ijece.v16i5.pp2782-2794
Aris Tjahyanto , Irmasari Hafidz , Faizal Johan Atletiko
Chatbots have recently gained significant popularity. For instance, ChatGPT has become a preferred tool for many individuals seeking instant answers without relying on human responses. This immediacy sets chatbots apart from books, which require users to search for information manually. This time-consuming process does not align with millennials' preference for convenience and efficiency. Studying hadith independently using the Bulugh al-Maram book demands considerable time and effort. The limited use of natural language processing technologies in religious chatbots restricts their ability to handle complex inquiries effectively. A chatbot capable of answering hadith-related questions could greatly assist the public in studying hadith texts by providing direct responses without extensive searching. This chatbot was designed for web browsers, utilizing deep learning as its core technology. This research led to the development of a chatbot prototype for learning hadith from Bulugh al-Maram. Built using the design science research (DSR) methodology, the prototype achieves an intent recognition rate (IRR) of 86.82%. However, its capabilities are below the BERT model, demonstrating a strong ability to accurately interpret user questions and statements.
Volume: 16
Issue: 5
Page: 2782-2794
Publish at: 2026-10-01

Calibration-guided score fusion for robust multimodal traffic anomaly detection

10.11591/ijece.v16i5.pp2516-2525
Quang Hiep Do , Thien Tan Nguyen
Multimodal traffic anomaly detection is affected by differences in visual and audio score ranges, temporal fluctuations, and unstable decision thresholds. This paper proposes a calibration-guided score fusion (CGSF) framework that processes video frames and audio spectrograms through separate reconstruction-based models. The resulting anomaly scores are temporally smoothed, normalized using validation data, and combined at the score level. A percentile estimated from normal validation samples is then used as the decision threshold. The framework was evaluated on the MAVD and DADA2000 datasets. On MAVD, CGSF achiev,,,,,,ed a ROC-AUC of 0.553, a PR-AUC of 0.082, and an F1-score of 0.129. It outperformed direct fusion in precision, recall, and F1-score, although the gain in ROC-AUC was small. Analysis on DADA2000 showed smoother temporal score behaviour after calibration and smoothing. The results indicate that CGSF mainly improves score comparability and threshold consistency rather than producing a large increase in detection accuracy. Its modular design also allows the visual and audio branches to be trained and updated independently.
Volume: 16
Issue: 5
Page: 2516-2525
Publish at: 2026-10-01

A compact tri-band THz patch antenna using slot-loaded radiator and defected ground structure

10.11591/ijece.v16i5.pp2549-2558
Tran-Thi Bich Ngoc , Truong Thi Phuong Nhi
Terahertz (THz)- based antennas are essential for future 6G sensing and short range communications, especially when multi-band flexibility and compact di mensions are required. This paper presents a compact microstrip patch an tenna designed for THz applications with tri-band operation. The antenna is formed out of a rectangular patch filled with slots, a defective ground structure (DGS), and a microstrip feedline. Slot loading and the DGS generate various current paths, exciting several resonant modes and enhancing impedance match ing across the resonant frequency range. The proposed design is implemented on a 30 µm thick RO3003 substrate with a relative permittivity of 3 and loss tan gent of 0.001. The antenna has physical dimensions of 0.27×0.28×0.03 mm3. Simulation results show the antenna operates at three frequencies with a remark ably low return loss of up to-61.35 dB over the range of 1.59-3.2 THz. It offers tri-band gains of 6.01 dBi, 7.30 dBi, and 7.31 dBi, with a voltage standing wave ratio (VSWR) close to the ideal value of 1 for most bands. Furthermore, field distributions and power breakdown calculations are performed to better under stand the radiation mechanisms and efficiency characteristics at THz frequen cies. The antenna radiated power across the band, achieving up to 86.5% of the power accepted. These results indicate that the suggested design provides tri-band capabilities while being a simple, compact and efficient candidate for the demand for improved antennas in next-generation wireless communication systems.
Volume: 16
Issue: 5
Page: 2549-2558
Publish at: 2026-10-01
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