Despite their potential as a sustainable energy technology, the operation of proton exchange membrane fuel cells (PEMFCs) in sub-freezing conditions remains a critical challenge due to the risk of ice formation and performance degradation. This study introduces a new passive thermal management technique using strategically arranged multi-layer phase change materials (PCMs) to address this challenge. A numerical model was developed to evaluate the thermal behavior across various PCM configurations, incorporating one, two, and three layers arranged both in parallel and series with distinct melting points ranging from 55 to 65 ◦C. The results show that multi-layer PCM configurations provide significant improvements over the single-layer base

The splicing design of the existing road and the new road in the expansion project is an important part of the design work. Based on the analysis of the characteristics and the load effect of pavement structure on splicing, this paper points out that tensile crack or shear failure may occur at the splicing under the repeated action of the traffic load on the new/old pavement. According to the current structure design code of asphalt pavement in China, it is proposed that the horizontal tensile stress at the bottom of the splicing layer and the vertical shear stress at other layers of the splicing line should be controlled by adjusting the position and size of the excavated steps in addition to the conventional design ind

This research investigated the effect of adding two groups of reinforcement materials, including bioactive materials Hydroxyapatite (HA) and halloysite nanoclay and bioinert materials Alumina (AL2O3) and Zirconia (ZrO2), each of them with various weight ratios (1,2,3,4 &5)% to the polymer matrix PMMA. The best ratios were selected, and then a hybrid was preparing Composite red from the best ratios from each group. Thermal properties, including thermal conductivity and Thermomechanical Analysis (TMA) technology, have been studied. The results showed that adding 3% Hydroxyapatite (HA) and 5% halloysite nanoclay to the polymethacrylate (PMMA) mer leads to an increase in thermal conductivity. It was also found from the Thermomechanical Analysis

Introduction: Surgical removal of impacted lower wisdom teeth is one of the most commonly performed proce- dures in oral and maxillofacial surgery. Objectives: This study aimed to compare the operative and post-operative outcomes of 2 flap designs (limited vs. extended 2-sided flap) in surgical extractions of lower third molars (M3) regarding fully impacted teeth. Material and methods: A prospective, randomized, controlled split-mouth trial was designed, and included 27 patients with bilateral (symmetrically positioned) impacted M3. Limited 2-sided flap was performed on one side (group 1) and extended 2-sided flap on the other side (group 2). The effect of flap design on intra-operative (visibility, accessibility, and duration of surgery) a

The effect of short range correlations on the inelastic longitudinal Coulomb form
factors for the lowest four excited 2+ states in 18O is analyzed. This effect (which
depends on the correlation parameter β) is inserted into the ground state charge
density distribution through the Jastrow type correlation function. The single particle
harmonic oscillator wave function is used with an oscillator size parameter b. The
parameters β and b are, considered as free parameters, adjusted for each excited state
separately so as to reproduce the experimental root mean square charge radius of
18O. The model space of 18O does not contribute to the transition charge density. As
a result, the inelastic Coulomb form factor of 18

The addition of organic-inorganic hybrid nanoparticles presents a promising avenue for enhancing both the ionic conductivity at room temperature and the mechanical resilience of solid polymer electrolytes (SPEs). In this study, a novel nanocomposite solid polymer electrolytes (NSPEs) based on poly(ethylene oxide)-lithium difluoro(oxalato)borate (PEO20-LiDFOB) incorporating polyhedral oligomeric silsesquioxane-poly(ethylene glycol) (POSS-PEG(13.3)) hybrid nanoparticles were developed. And also reported the effect of POSS-PEG(13.3) hybrid nanoparticles on the structural, thermal, electrical, mechanical, and electrochemical properties of the (PEO20-LiDFOB) SPE. X-ray diffraction (XRD), differential scanning calorimetry analysis (DSC) and polar

        The research deals with the analysis of the city's commercial center using geographic information systems to solve the problem of congestion by evaluating the efficiency and adequacy of car parking lots according to local and Arab standards. Undoubtedly, the importance of car parking areas, as they are not within the desired efficiency within the city, will lead to congestion and traffic becomes very difficult. Thus, the transportation service loses its most important characteristic, which is the ease of movement. Therefore, there has become an urgent need to study and analyze it, as well as to verify the adequacy of the service, and the amount of deficit required to be provided to solve the tra

This effort is related to describe and assess the performance of the Iraqi cement sample planned for oil well-cementing jobs in Iraq. In this paper, major cementing properties which are thickening time, compressive strength, and free water in addition to the rheological properties and filtration of cement slurry underneath definite circumstances are experimentally tested. The consequences point to that the Iraqi cement after special additives encounter the requests of the API standards and can consequently is used in cementing jobs for oil wells. At this research, there is a comparative investigation established on experimental work on the effectiveness of some additives that considered as waste materials which are silica fume, bauxite,