. In this article, we consider the problem of approximating the solution of bilevel split variational inequality problem in real Hilbert spaces. The underlying operators in the lower level problem are quasimonotone and Lipschitz continuous. The proposed algorithm is a combination of the modified subgradient extragradient and modified Tseng's extragradient methods. Compared with the existing modified subgragadient extragradient methods for solving bilevel split variational inequality problem, our suggested method does not required computation of the projections onto two half-spaces, containing the feasibility sets. The step sizes employed in our algorithm do not need the prior knowledge of the norm of the bounded linear operator and the the Lipschitz constants of the underlying operators. We obtain the strong convergence results of the new method using some mild conditions on the control parameters. The proposed method involves double inertial terms which permits it to accelerate its convergence speed. To show the advantage and potential of our method over some existing methods, we present some numerical experiments. direction.
Particle shape irregularity governs grain-scale interactions that influence dune stability and surface mobility in aeolian environments, yet its effects remain poorly quantified in constitutive models. This study presents a micromechanical investigation into the constitutive behavior of aeolian dune sand (ADS) at the scale of representative volume element (RVE), with a specific focus on the fundamental role of particle irregularity. Through a series of discrete element method (DEM) simulations incorporating high-fidelity particle shapes, assemblies with varying overall regularity ( O_R ) indices are systematically analyzed under direct shear test conditions, with varying packing density and normal stresses. The results reveal that as O_R decreases, both the peak and critical state shear strength increase non-linearly, demonstrating a saturation effect at high particle shape irregularity. A novel asymptotic model, φ =B-A(O_R)^n , is proposed, which provides a superior fit than the traditional power-law models by capturing this physical limit and implying an upper-bound strength for the ADS. A corresponding enhancement in dilatancy is observed, governed by a stress-dilatancy relationship with a material constant of 0.61, specific to the morphology of ADS. Micro-structural analysis shows that the evolution of fabric anisotropy and the mechanical coordination number strongly correlate with the macroscopic stress-strain response, with more irregular particles developing a more stable and anisotropic load-bearing network. A key finding is the establishment of unified scaling laws where the particle regularity index directly governs the pressure-dependence of both the critical state void ratio and coordination number. This provides a cross-scale framework linking particle irregularity to the bulk constitutive behavior, offering a micromechanical basis for the development of enhanced constitutive models for granular materials in aeolian environments.
This study investigates electrode-dependent resistive switching in sodium alginate (SA)-based resistive random-access memory (ReRAM) devices and evaluates their thermal stability and aging effects. Four device architectures-Ag/SA/Al, Ag/SA/ITO, Ag/SA/Ag, and Ag/SA/Cu-were fabricated using a drop-casting method and characterized for electrical performance under varying conditions. Among these, the Ag/SA/Cu device exhibited better characteristics, including a low switching voltage (similar to 1.0 V), strong hysteresis, high ON/OFF ratio, and excellent endurance over 1000 cycles. Temperature-dependent analysis (25-95 degrees C) revealed stable switching behavior despite minor morphological changes and increased signal noise, confirming robustness under thermal stress. Mechanistic insights indicate that electrochemical metallization (ECM) driven by Cu2+ ion migration governs the switching process. These findings highlight the importance of electrode selection in optimizing biodegradable memory materials and underscore the potential of SA-based ReRAMs for sustainable, non-volatile memory applications in environments subject to thermal fluctuations.
River water quality is a critical issue as it directly affects both human health and biodiversity. In the CubangoKavango River (CKR) basin, located in Angola, Namibia, and Botswana, anthropogenic and agricultural activities have increased, which exerts significant pressure on the river. This study assessed the suitability of the CKR basin water for human consumption at 12 different sites along the river. A total of 88 water samples were collected throughout the river in two phases: the dry season (August) and the wet season (March). Water quality (WQ) was analyzed both in the field and at the NamWater laboratory using a HANNA HI 9829 multiparameter instrument and an ion spectrophotometer Eco IC Metrohm, respectively. The Water Quality Index (WQI) was calculated based on the weighted arithmetic method using the following water parameters: Total Nitrogen (TN), Nitrate (NO3-), Nitrite (NO2-), Ammonia (NH3), Organic Nitrogen (ON), Total Phosphorus (TP), Orthophosphate (PO43-), Electrical Conductivity (EC), pH, Dissolved Oxygen (DO), Total Dissolved Solids (TDS), and Chlorophyll-a (Chla). The result obtained showed that the levels of NH3 and DO exceed the World Health Organization (WHO) 2022 guidelines, and the levels of NH3, NO2- and Chl-a exceeded the 2023 Namibian Water Quality Guidelines (NWQG). The WQI values ranged as good water (32.13) at Calai, to (39.12) at Ndonga Linena during the dry season. In the wet season, the WQI value ranged as good water as well (31.86) at Rundu and 42.60 at Nkurenkuru. The WQI values indicate that the overall WQ is suitable for drinking; however, continuous monitoring is needed to further assess the impact of human activities within the CKR.
Digital literacy is central to student success in technology-mediated higher education, particularly in resource-constrained environments. This study introduces the Digital Literacy Course for Learning Management Systems (DLC4LMS), an equity-sensitive instructional design framework that synthesises the ASSURE model, Universal Design for Learning (UDL), Community of Inquiry (CoI), EquityXDesign, and Laurillard’s Conversational Framework. Guided by Design Science Research (DSR), the study followed three iterative cycles: (1) relevance, identifying digital literacy gaps among first-year students; (2) design and development, constructing the DLC4LMS framework through theoretical integration and stakeholder input; and (3) rigour and evaluation, formatively validating the framework with academic staff at two South African universities. Findings suggest the importance of embedding equity as a design driver, integrating mobile-first tools, and linking digital literacy to both academic survival and employability. The DLC4LMS extends existing instructional design models, traditionally developed in well-resourced contexts. By adapting them for low-bandwidth, mobile-only, and equity-challenged universities. While developed in South Africa, its principles are transferable to similar Global South and humanitarian education settings. This research contributes a theoretically grounded, context-responsive model that advances inclusive digital transformation in higher education.
