Journals
2026 EN
Ma Jingyi · Guo Daquan · Zhao Zhongxiang
+3 more
Abstract This study investigates the variability of internal tides in the Arabian Sea from 2003 to 2019 using a three‐dimensional high‐resolution general ocean circulation model forced by realistic forcing. The model reveals their key generation sites including around Socotra Island, the Carlsberg Ridge, the Maldives, and the northeastern Arabian Sea. The analysis of depth‐integrated kinetic energy and energy flux reveals significant spatial and temporal variability driven by seasonal, interannual, and multi‐year climatic factors. Peak activity occurs in summer and winter due to the monsoonal cycle, and a quasi six‐year modulation is also evident in the internal tide energy. Correlation analysis shows that internal tide energy is strongly linked to upper ocean stratification on seasonal time scales, but this relationship weakens markedly after removing the climatological cycle, indicating that their interannual covariance is limited and influenced by additional processes. Empirical Orthogonal Function analysis further clarifies the dominant spatial and temporal patterns. The leading mode represents a basin‐wide coherent response, while the second mode highlights an out‐of‐phase structure between the major generation regions and the remote propagation pathways. These results reveal the complex variability of internal tides in the Arabian Sea and underscore the influence of both stratification and large‐scale environmental fluctuations on their modulation.
Journals
2026 EN
Bansal Atul · Ibrahim Mohamed · Yuan Kuang
+3 more
Abstract Radio Quiet Zones (RQZs) have been established to prevent radio sources from causing harmful interference to sensitive radio telescopes, which study extremely faint cosmic radio waves. Even with strict regulations, such interference is growing due to the widespread use of consumer electronics, emitting in many different frequency bands, including Wifi, Bluetooth. Removal of interferers is often a matter of sending trucks with spectrum analyzers to perform localization, using signal power‐based localization techniques, a human‐intensive process. We present TranQuiL, a novel long‐range detection and localization system that can detect and localize an interfering transmitter at large distances. Our key innovation is the development of an improved beacon packet detection pipeline, which enables significant range improvement. We implement and evaluate our system for an interfering WiFi and Bluetooth transmitter across two testbeds: (a) the Green Bank Observatory in West Virginia and (b) around a large manufacturing facility in a major U.S. city. We demonstrate a localization accuracy of 13.2 m in both test beds from 950 m away for WiFi transmitters and 450 m for Bluetooth transmitters, sufficient for building‐scale identification of the interferer's location.
Journals
2026 EN
Nana Ibrahim · Tabe-Ojong Martin Paul Jr
Global value chains offer countries unique opportunities to participate in and benefit from international trade by specializing in specific production stages and tasks. This study investigates the evolution in the participation of African countries in global value chains and assesses the impact of global value chain participation on economic growth over the period 1990–2022. Using the EORA Multi-Region Input-Output tables, it tracks the evolution of global value chains, identifies specialization patterns, and generates sector/task global value chain participation measures. Employing both instrumental variable and local projection methods, the study further examines the relationship between global value chains and economic growth, providing evidence on the sectors that drive this relationship. The findings suggest that African countries’ participation in global value chains is positively associated with their economic growth. This positive association is primarily driven by trade in knowledge-intensive services, labour intensive goods and commodities. These results suggest that participating actively in global value chains could serve as a crucial entry point for fostering economic growth in African countries.
Journals
2026 EN
Aydin Kadir · Karaağaç İbrahim · Kabakçi Mehmet Okan
This study investigated the effects of the Hot Isostatic Pressing (HIP) process and heat treatments on the deformation strength and microstructure of AlSi10Mg parts produced by the additive manufacturing method. The bending process tested the deformation strength of the additively manufactured parts at 15, 30, 45, 60, and 75 degrees. It was observed that Si particles, which increase brittleness, were dispersed in the dendritic structure of the Al matrix in the microstructure of the as-built parts. After the HIP process, there was an increase in the grain size of the Si particles that coalesced and agglomerated, but a decrease in the number of grains. This situation caused a significant rise in deformation strength in HIP samples, and these parts could be deformed without cracking or breaking at a maximum die angle of 75 degrees. However, after the stress-relieving process, the specimens could be deformed at a maximum die angle of 15 degrees. It was determined that the tensile strength value, 341 MPa in the as-built specimens, decreased to 110 MPa in the HIP specimens, and the hardness value decreased from 131 HV to 62 HV.
Journals
2026 EN
Ibrahim Murtala
This article examines vigilante security governance in the Nigerian city of Jos. Focusing on the Vigilante Group of Nigeria (VGN) and Neighbourhood Watch, I explore how vigilantes in Jos have reproduced and enhanced their authority by positioning themselves as potential victims of violence perpetrated by criminal gangs. In order to understand how vigilantes cultivate their authority in the city, I propose the notion of hemato-politics (politics of blood). Hemato-politics is the strategic deployment of human blood as a biomaterial medium of exchange that enables vigilantes to trade hematic self-sacrifice for power and authority over their local communities. Hemato-politics is partly performed through the distribution and circulation of images of wounded bleeding bodies, which serve as a spectacular and persuasive visual technique that attracts sympathy and solidarity from communities. Vigilantes’ authority is thus inextricably linked to their relationship with their communities, as mediated by an aesthetic of corporeality and visuality.
Journals
2026 EN
Özyurt Gülcan · Usta İbrahim
This study evaluates a Zirconium-based conversion coating as an eco-friendly alternative to conventional phosphating for welded aluminium alloys. Conventional phosphating often results in uneven coatings on high-silicon alloys and welded areas, reducing adhesion and corrosion resistance. The proposed chromium-, nickel-, and phosphate-free pretreatment contains hexafluorozirconic acid, organic silanes, stabilisers, and complexing agents, forming a thin, amorphous zirconium oxide layer that enhances paint adhesion and corrosion protection. The coating system was applied to 3103 and 5754 aluminium alloys and evaluated in two configurations: cataphoresis alone and a duplex system of cataphoresis followed by wet paint application. Compared to phosphating, salt spray tests and surface analyses showed that the Zirconium-based treatment provides more uniform coatings, better adhesion, and significantly improved corrosion resistance. These results demonstrate the method’s technical effectiveness and environmental compliance, making it a promising surface preparation technique for automotive and industrial applications.
Journals
2026 EN
Ali Khalid K. · Mohamed Mohamed S. · Ibrahim Amira Abd-Elall
+2 more
The goal of this work is investigating the existence and uniqueness of solutions for a class of non-local Riemann-Liouville fractional q -integro-differential equations, in addition to finding the approximate solutions to the proposed equation. The problem incorporates Riemann-Liouville fractional derivatives, Riemann-Liouville fractional q integral, and a q -nonlocal boundary condition. By leveraging the Schauder fixed-point theorem and the Banach contraction principle, we establish rigorous conditions under which solution exists and is unique. These mathematical methods are vital for determining the existence and uniqueness of a solution for a class of non-local Riemann-Liouville fractional q -integro-differential equation. Five illustrative examples validate the theoretical results, demonstrating the applicability of the proposed framework. Furthermore, a neural network-based approach is employed to approximate solutions, achieving high accuracy with minimal error, as evidenced by detailed simulations. The integration of theoretical analysis and computational methods highlights the effectiveness of the approach in addressing complex fractional systems.
Journals
2026 EN
Ager Paul · Jimoh Isah A. · Bevan Geraint
+1 more
This work presents an adaptive backstepping controller using a radial basis function neural network (RBF-NN) for position control of a linear motor drive with parameter uncertainties, discontinuous friction and unknown external disturbances. Initially, a robust control scheme is developed to ensure asymptotic stability. To avoid conservative tracking performance, we propose an adaptive robust backstepping law incorporating an RBF-NN to estimate lumped uncertainties and disturbances. The dynamic determination of the approximation error upper bound eliminates discontinuities in the adaptive control law. The RBF-NN's characteristics are utilised to establish the existence of solutions for the system, ensuring that the adaptive control law satisfies the Lipschitz continuity condition. The developed scheme ensures global asymptotic stability under bounded disturbances. Simulation results validate the proposed scheme's effectiveness in achieving precise positioning and reducing chattering compared to a robust backstepping controller, a fast nonsingular terminal sliding mode controller and an adaptive recursive terminal sliding mode controller.
Journals
2026 EN
Loukam Imed · Hellal Aouatef · Djeddou Messaoud
+2 more
The resistance coefficient is a key parameter in free-surface flow modelling, influencing velocity distribution, drainage capacity and energy dissipation. Traditionally derived from Manning’s and Chézy’s equations, its calibration in urban environments is challenging due to the combined effects of viscosity, geometry, wall conditions and slope. This study compares deep neural networks and conditional generative adversarial networks for predicting the Manning coefficient using discharge, kinematic viscosity, surface roughness, slope, and filling ratio. The deep neural network achieved higher accuracy, with a mean relative error of 1.27% and a coefficient of determination of 0.9753, compared to 2.26% error and 0.9159 for the conditional generative adversarial network. Only 4.34% of deep neural network predictions exceeded a 5% error tolerance, compared to 15.8% for the conditional generative adversarial network. Both models demonstrated reliable uncertainty quantification and generalization, highlighting viscosity and roughness as dominant factors shaping hydraulic resistance behaviour.
Journals
2026 EN
Seven Berfin · Hatun Osman · Demirci İbrahim
This study aimed to examine the relationship between psychological flexibility and ontological well-being among adults. The participants consisted of 477 adults aged 18 to 65 years ( M = 25.84, SD = 7.62), recruited through convenience sampling. Data were collected using a demographic information form, the Psychological Flexibility Scale, and the Ontological Well-Being Scale. Pearson correlation analysis, multiple regression analysis, and independent samples t-tests were conducted to analyze the data. The results indicated that psychological flexibility was positively associated with ontological well-being. Furthermore, male participants and those who were married or in a romantic relationship reported higher levels of psychological flexibility and ontological well-being. Additionally, even after controlling for age, gender, relationship status, and socioeconomic status, the sub-dimensions of psychological flexibility significantly predicted ontological well-being. The strongest predictors of ontological well-being were the defusion, acceptance, and present-moment-awareness sub-dimensions of psychological flexibility, respectively. In conclusion, interventions aimed at enhancing psychological flexibility may contribute significantly to improving ontological well-being among adults.