Transactions on Engineering and Computing Sciences

Experimental Results and Modeling of Magnetic Data for the Gallium Oxide-Hematite Mixed-Oxide Nanoparticles

Monica Sorescu, Felicia Tolea, Mihaela Sofronie — Fri, 28 Nov 2025 00:00:00 +0000

The xGa₂O₃*(1-x)Fe₂O₃ (x=0.5) was prepared by mechanochemical activation using high energy ball milling for times of 0, 2, 4, 8, and 12 hours. The magnetic properties were studied by hysteresis loop measurements with an applied magnetic field of 5 T at temperatures of 5 and 300 K. Zero-field-cooling-field-cooling results were obtained in a magnetic field of 200 Oe in the temperature range 5-300 K. The magnetization and average coercive field were investigated as functions of ball milling time and temperature. They were related to changes in the average grain size, induced stresses and defects, variations in exchange coupling and magnetic ordering. ZFC did not exhibit a sharp edge, so we do not witness superparamagnetism with a well-defined blocking temperature. The Morin transition of hematite occurred over broad temperature ranges and was monitored as a function of ball milling time. The Dzyaloshinskii-Moriya antisymmetric exchange interaction explained the gradual increase in the magnetization with ball milling time.

The Joint Effect of Organizational Characteristics, Governance Reforms, and Stakeholder Management on the Performance of Ports in Africa

Joseph Atonga, Zachary Awino, Kennedy Ogollah, Stephen Odock — Thu, 06 Nov 2025 00:00:00 +0000

The key purpose of carrying out this research was to determine the joint effect of organizational characteristics, governance reforms, and stakeholders’ management on the operational performance of seaports from Africa. The research philosophy employed by the study was positivism with a descriptive cross-sectional census survey design. Structured questionnaires were deployed to collect primary data from 46 top executives of seaports in Africa that specialize in handling containers. The rate of response was response rate was 83%. Additional published data was also obtained from the websites of some of the ports. Reliability and validity for the indicator items were ascertained through diagnostic tests. Model fitness was ascertained by obtaining ratios of SRMR and NFI. Data analysis was carried out by Partial Least Squares Structural Equation Modelling (PLS-SEM) using Smart PLS4.1 software. PLS-SEM was also used to test the hypothesis that the joint effect of organizational characteristics, governance reforms, and stakeholders’ management on the operational performance of seaports from Anglophone Africa was not significantly greater than the individual effect of each variable on the performance. The individual effects of each variable with their moderating effects were the first to be determined through PLS-SEM before finally establishing the joint effect of the three exogenous constructs. The finding established that the joint effect was greater than the individual effect of each variable and concluded that a joint application of the three variables greatly improves the performance of seaports in Africa, thereby enabling them to gain a competitive advantage. The study adds to new knowledge, policy, and practice by enabling managers, policy makers and governments, and regulators to expand, plan, build, and operate new ports from an informed point of view.

A Robust and Adaptive Lyapunov-Sliding Mode Control Strategy for Electric Motor Applications

Tidiane Diaby, Mohamed Ali Zohdy, Adnan Shaout — Sun, 09 Nov 2025 00:00:00 +0000

This paper presents a robust and adaptive control strategy that integrates Lyapunov-based stability and Discrete Time Sliding Mode Control (DTSMC) for speed tracking, and stability enhancement in electric motors. The proposed approach leverages Lyapunov theory to guarantee system stability by designing a positive definite Lyapunov function, ensuring the convergence of tracking errors under varying operating conditions. Simultaneously, the discrete SMC provides robust disturbance rejection and resilience to parameter variations by maintaining system states on a predefined sliding surface. The combination of these two methods addresses the limitations of conventional controllers, which often lack robustness to uncertainties and Disturbances. The effectiveness of the proposed method is validated through theoretical analysis and simulation results on PMSM model, demonstrating superior tracking performance, under different load conditions and system uncertainties.

Seniors in the Digital Age: Perceptions, Adaptation and Inclusion

Sunita Narang, Shalu Mahajan, Preeti Marwaha, Sharanjit Kaur, Gunjan Rani — Tue, 11 Nov 2025 00:00:00 +0000

Digital technology has transformed society over the past two decades. Despite numerous advantages, it is still posing challenges for seniors. While some older adults have embraced these changes, others struggle with digital literacy. Bridging this gap is essential to ensure that seniors can fully participate in the rapid digital transformation. This research explores the perceptions of 359 seniors towards digital transformation and evaluates their adaptation levels. Employing an integrated statistical and machine learning framework, the study reveals that seniors widely recognize the use of digital technology across education, entertainment, healthcare, e-commerce, and communication. Their primary online activities include entertainment, payments, and social networking. Seniors emphasize on the provision for basic computer skill training and secure online environment for the improved digital experience. However, the willingness to adapt with digital transformation varies within seniors. Results indicate a statistically significant difference (p<.05) in willingness to enhance technical knowledge across demographic variables viz., age, marital status, area of residence, education level and work profile. Senior citizens are divided into four segments viz., Functional Adopters, Social Adopters, Reluctant Adopters, and Tech-Savvy Pioneers by using K-means clustering algorithm considering their digital adoption. It is recommended to make tailored policies for inclusion of Indian senior citizens in the digital mainstream as per their segment. Literacy programs, infrastructure and community support may play a critical role for the same.

Coupled Statistical–Numerical Framework for Predicting Droplet Temperature in Gas Metal Arc Welding

Victor Avokerie Ijoni, Joseph Ifeanyi Achebo, K. O. Obahiagbon, F. O. Uwoghiren — Thu, 20 Nov 2025 00:00:00 +0000

Accurate prediction of droplet temperature during Gas Metal Arc Welding (GMAW) is crucial for controlling metallurgical outcomes and process stability, yet direct measurement remains a challenge due to the rapid thermal dynamics involved. This study aims to develop and validate both empirical and physics-based models to estimate droplet temperatures during GMAW. A total of 20 experimental runs were performed using mild steel (AISI 1018) under a Central Composite Design (CCD), varying welding current (240–270 A), voltage (23–26 V), and wire feed rate (2.4–3.0 mm/s). Droplet temperatures were measured with a high-resolution pyrometer and modeled using Response Surface Methodology (RSM) in Design Expert and a 1D Finite Element Method (FEM) implemented via MATLAB. The RSM model showed high accuracy with an RMSE of approximately 4.3 °C compared to experimental results, while the 1D FEM model achieved an RMSE of 192.7 °C, capturing the general thermal trend despite simplifications such as constant properties and 1D heat conduction. These findings demonstrate the complementary strengths of empirical and computational approaches: RSM offers precise data-driven predictions, while FEM provides a deeper physical understanding of heat transfer during droplet formation.