Advances in Science and Technology Vol. 179

Abstract: Lightweight modular buildings deployed in desert environments operate under severe climatic stress, facing extreme daytime temperatures, large diurnal swings and intense solar radiation. These conditions drive continuous heat ingress into the interior and impose thermal fatigue on the building envelope. While insulation materials are typically selected based on steady-state thermal conductivity values, these metrics do not capture transient heat penetration, thermal lag or the mechanical response induced by cyclic temperature loads. This work presents a thermal–mechanical performance-mapping framework that evaluates insulation materials under realistic desert boundary conditions. A multilayer cabin wall is modeled using measured Kuwait summer temperature cycles and solar-equivalent heat flux. Transient one-dimensional heat-transfer analysis is combined with thermo-elastic stress estimation to evaluate polyurethane foam, polyisocyanurate, expanded polystyrene and mineral wool. Dynamic indicators—including interior temperature moderation, thermal lag and normalized daily heat gain—are used to compare performance. The findings reveal substantial discrepancies between laboratory-rated and climate-specific behavior and highlight the need for integrated evaluation when selecting insulation for buildings in extreme climates.

Abstract: This study investigates the effect of membrane thickness on proton exchange membrane fuel cell (PEMFC) performance through high-fidelity computational fluid dynamics (CFD) simulations using the open-source platform OpenFOAM. Seven membranes with thicknesses of 20, 25, 30, 40, 50, 127, and 183 μm were evaluated to generate polarization and power density characteristics. Results reveal that membrane thickness exerts a substantial influence on PEMFC efficiency, with thinner membranes reducing ohmic resistance and enhancing proton conductivity, albeit with trade-offs related to water management and gas crossover. The findings underscore the necessity of optimizing membrane thickness to achieve an optimal balance between efficiency, durability, and operational stability, offering valuable insights for the design and development of next-generation PEMFC systems.

Abstract: Silicon oxide–carbon (SiOx–C) negative electrodes exhibit diminished performance at reduced temperature. This study isolates the role of electrolyte salt in EC/DMC half‑cells by holding the electrode formulation, separator, potential window, and current density constant and comparing 25°C and 15°C. Galvanostatic profiles and electrochemical impedance spectroscopy were used to quantify polarization, capacity, and interfacial resistance. On lowering to 15°C, all salts showed increased polarization; the severity followed LiCF₃SO₃ ≳ LiClO₄ > LiPF₆ ≫ LiBF₄. Nyquist spectra exhibited the same ordering in the growth of the mid‑frequency arc. At 25°C, the durable capacity ranking was LiBF₄ > LiPF₆ > LiClO₄ > LiCF₃SO₃. Under the fixed protocol, capacities at 15°C collapsed toward low values for all salts, indicating a kinetic penalty sufficient to trigger premature voltage cutoffs. LiBF₄ minimized the increase in interfacial resistance but did not preserve capacity at 15°C. The data show salt-dependent low-temperature kinetics in SiOx–C and indicate that operation near 15°C requires lower current density, adjusted potential windows, or deliberate control of interphase and solvation chemistry.