ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY AND ENVIRONMENT

Optimization of Periwinkle Shell Ash and Sawdust Mixture as Additives in Fired Clay Brick Using Grey Relational Analysis in Taguchi Methodology

S. O. Jimoh, F. O. Anafi, A. M. Na'inna — Tue, 01 Sep 2026 11:54:30 +0000

The use of additives remains one of the methods of enhancing compressive strength and thermal conductivity of a clay bricks used for various applications in the construction industry. However, obtaining the right mixtures of additives remain a concern by most researchers. In this study, an experimental and modelling approaches were used to determine optimum mixture of periwinkle shell ash (PSA) and sawdust (SD) additives at 5-20 % by weight at 900-1100oC firing temperature on fired bricks. The objective of the study was to evaluate the thermo-mechanical properties of the additives with a view to minimizing thermal conductivity and enhancing compressive strength. Consequently, an optimal thermal conductivity of 0.3486 W/mK was obtained for the additives using a control factor setting of SD10PSA15FT1100. In case of an optimum value for a compressive strength, a value of 8.2234 MPa was obtained employing a control factor setting of SD10PSA10FT1100. The estimated values obtained in the present study aligned with the suggested thermal conductivity of less than 0.6 W/mK and the proposed minimum compressive strength of at least 7 MPa. This fulfils the "Lower the Better" and "Higher Better" criterion for thermal conductivity and compressive strength respectively. In addition, a close relationship between predicted and experimental values of thermal conductivity affirmed the acceptance of the prediction model with an R-squared value of 96.25%. Conversely, as for the compressive strength, the predicted and experimental values exhibited a close relationship where the prediction model also boasts an R-squared value of 89.93%, signifying its strong acceptability for accurate predictions. The present study will be utilized in optimizing the quantity of additives used in the production of clay fired bricks for various industrial heat containment and eco-friendly applications.

Crowd-Induced Vibration Serviceability of Reinforced Concrete Lecture Theatre Floors: Taraba State University

K. U. Unamba, E. A. Medjor, J. Y. Saleh — Tue, 01 Sep 2026 12:16:41 +0000

Overcrowding in Nigerian public university lecture theatres has created a severe structural loading problem that engineers have rarely confronted systematically: crowd-induced dynamic loading that far exceeds the live loads assumed at the design stage. This study investigates the vibration serviceability of reinforced concrete floor systems in six lecture theatres at Taraba State University (TSU), Jalingo, where observed peak occupancies reached as high as 211% of design capacity. In-situ ambient vibration testing via the Stochastic Subspace Identification (SSI) algorithm, calibrated finite element modelling in ETABS, and multi-harmonic crowd load simulation were combined to characterise structural responses across six loading scenarios. Fundamental floor frequencies of 4.08 to 6.83 Hz were recorded, with the lowest values concentrated in flat-slab theatres whose wide spans placed them squarely in the resonance band for the second harmonic of rhythmic crowd activities near 4.2 Hz. Modal Assurance Criterion (MAC) values of 0.84 to 0.97 across the first three bending modes confirmed adequate model fidelity beyond the fundamental frequency alone. A supplementary boundary condition study showed that semi-rigid column base assumptions improved the mean frequency prediction error from 4.8% to 2.1%, though serviceability classifications were unaffected. Parametric sensitivity analysis for three theatres whose structural details were estimated rather than drawing-verified showed that natural frequency predictions varied by no more than 4.9%, with compliance classifications unchanged across every perturbation. Under rhythmic crowd loading at 150% of design capacity, peak floor accelerations reached 0.61 m/s2 in the most critical theatre, exceeding the ISO 10137:2007 assembly area limit of 0.45 m/s2 by 36%. Dynamic amplification factors of 1.42 to 3.89 were recorded, driven primarily by near-resonance excitation of flat-slab floors. The study recommends graduated interventions ranging from administrative occupancy limits to structural retrofitting, and makes a case for explicit vibration serviceability provisions in Nigerian design standards for educational facilities of this nature.

Design and Implementation of An Offline-Optimized Web-Based Course Material Management System for Engineering Education in Resource-Constrained Universities

O. O. Ashama, R. A. Ekemube, B. O. Okoyomoh, M. A. Ikechukwu — Tue, 01 Sep 2026 12:37:36 +0000

Access to structured academic materials has been a major problem for engineering education in university system. This is because students always depend on fragmented channels, including social media groups, photocopied handouts, and peer-to-peer sharing to obtain learning resources. This study aims to design, implement and evaluate an offline-optimized web-based course material management system for engineering education in resource-constrained universities. The design of this system was carried out by mixed-method research design in combination with questionnaire-based needs assessment, and software development. Furthermore, post-deployment performance evaluation was carried out for the research design. The study collected a total population consisting of six hundred and forty (640) valid student responses,. The system development was carried out using ReactJS for the frontend interface, Flask for backend services, PostgreSQL for structured data management, and Amazon Web Services S3 for secure cloud storage. Other tools included in the development of the system were Docker and Digital Ocean hosting. Security features such as password hashing, HTTPS communication, and role-based access control. The usability post-deployment test was carried out at score rate of 5, the results showed that respondents’ (students) experienced difficulty in accessing academic materials at 95%. In addition, students expressed willingness to adopt the proposed platform at 91%. The usability post-deployment test showed a high overall satisfaction score of 4.62 of 5 score, at strong ratings for navigation, file accessibility, and download speed. The technical evaluation result showed reliability of system performance at an average response time of 1.84 seconds and 99.2% uptime. Hence, the system developed has provided a sustainable model that could be replicated across engineering faculties and similar higher education institutions in need.

Hybrid Incremental Conductance–Model Predictive Control for Maximum Power Point Tracking Under Varying Irradiance and Temperature Conditions

M. A. Jada, M. Musa, S. Ibrahim, T. A. Aljazuli, Y. Hassan — Tue, 01 Sep 2026 13:36:34 +0000

Photovoltaic systems experience variations in irradiance and temperature that continuously shift the maximum power point, making effective MPPT essential for maximizing energy extraction. Conventional methods such as Perturb and Observe and Incremental Conductance are simple to implement but may suffer from slow convergence, oscillations, and reduced accuracy under rapidly changing conditions. Model Predictive Control offers faster dynamic response but at the cost of higher computational requirements. This study developed a hybrid Incremental Conductance–Model Predictive Control algorithm for photovoltaic MPPT. The Incremental Conductance stage generated the reference voltage, while the finite-control-set predictive controller selected the switching state of the boost converter that minimized the voltage-tracking error. The controller was implemented in MATLAB/Simulink and evaluated at irradiance levels of 1000, 800 and 500 W/m², with cell temperatures ranging from 25°C to 35°C. Its performance was compared with that of a conventional Perturb and Observe–Model Predictive Control method. The proposed controller achieved a tracking efficiency of 98.8%, compared with 96.9% for the conventional controller. In addition, the overall settling time decreased from 100 ms to 70 ms, while the steady-state power oscillation was reduced from 8.5 W to 2.3 W. Similarly, the controller was observed to have produced lower overshoot and a faster rise time. These simulation results show that the hybrid IN-MPC method improved energy extraction, transient response and steady-state stability under the investigated operating conditions. However, this study recommends both eexperimental and hardware-based studies to confirm its real-time performance.