1,721,442 research outputs found
Experimental study of fatigue age on SUP-9 leaf spring steel which received heat treatment and shot peening processes
No full textOne aspect of the technical defect of leaf springs that are subjected to dynamic loads is fatigue defects which cause failure, as a result of uneven road surface or impact. Then leaf springs are expected to have a higher fatigue resistance limit. To improve the mechanical properties of leaf spring steel by providing heat treatment and shot peening processes, which will provide compressive residual stress to the surface, thereby improving the fatigue resistance of the spring. In this study, SUP 9 steel specimen has dimensions of 7 mm and a width of 50 mm, the heat treatment process is carried out at an austenitizing temperature of 920⁰C and 480 ⁰C temper temperature, for shot peening it is carried out at a pressure of 5 kg / cm², a shot diameter of 0.8 mm, with a peening time of 15 seconds, 17 seconds and 20 seconds, and testing of tensile, hardness, fatigue, residual stress, and fractography. This study shows that for a long shot time, good results are obtained, namely, the fatigue life has increased 8.7 times from the fatigue life of the spring steel without shot peening with application stress of 217 N / mm², and the residual stress is -847.39 N / mm²
Prevalence of tooth loss in Saudi Arabian school children: an epidemiological study of Saudi male children
No full textThe present study was carried out to determine the prevalence of tooth loss in Saudi male children with
adolescent dentition. Five hundred school-children were investigated, selected randomly from Riyadh
City. The age group of the examined sample ranged from 13 years and 6 months to 14 years and 6 months.
Clinical and radiographic examination were performed. The findings revealed that the total prevalence
of lost teeth, including extractions, hypondontia, and trauma was 13.6%. Tooth extraction was the most
dominating cause of tooth loss (8.6%), followed by hypodontia (4%) and trauma (1%). The mandibular
first molar was the most frequently extracted tooth, the mandibular second premolar showed the highest frequency
of agenesis and the central incisors were mainly affected by trauma.Corresponding Author:
Dr. S. Al-Emran, Associate Professor, Department of Preventive Dental Sciences,
King Saud University, College of Dentistry
P.O. Box 60169, Riyadh-11545, Saudi Arabia.
Email: [email protected]
Crushing behavior of foam filled steel extrusion / Al Emran Ismail
No full textThe concern of vehicle structural integrity and safety is given highly considerable amount of research and development by engineers and scientist world wide. Weight reduction of structures without compromising the structural durability is the important aspect because weight is strongly related to fuel consumption. In this work, rigid polyurethane foam is used to fill into steel extrusions. Different foam density is used to reinforce the steel tubes and at the same time different steel wall thickness also adopted to study the crushing behavior under quasi-static compression loading loaded at different angles. Force versus displacement of each column condition is recorded automatically, compared and analyzed. The area under the curve represent the energy absorbed by the column and the column length is properly designed to prevent buckling which will be resulted catastrophic failure leading to low energy absorption capability. Then, the final crushed columns are analyzed to study the correlation with the crushing characteristics. It is found that the energy absorption increased when increasing the foam density but when the tube wall reached a maximum thickness, the foam density no longer affected to increase the energy absorption
Assessment of thermal energy storage integrated solar thermal collector system: a review
No full textRenewable solar energy is clean, abundant and globally available although intermittent in nature, thus requires storage ability whereby the solar radiation can be utilized and store simultaneously, the excess reuse during cloudy weathers and night time when there is no solar radiation. Continuous investigations by many researchers have shown that the integration of thermal energy storage (TES) to solar collector could improve the system performance and extend their utilization beyond solar radiation hours. Several studies utilizing different energy storage materials such as phase change materials (PCM), nanomaterials, PCM nanomaterials and hybrid PCM materials have reported improved heat transfer mechanism in solar thermal collectors. However, the demerits on weight, size and space increment, leakages and poor heat transfer mechanism caused by the PCM-TES incorporation with solar thermal collectors still persists despite the several research attempts on development of new smart PCM-TES materials and their incorporation. Thus far, the current mini-review paper attempts to bridge the literature gaps on past and recent PCM-TES integration techniques used for solar thermal collector systems. In addition, the performance analysis of existing designs, material fabrications and suggested improvement are discussed in this paper
Crack behavior of heat treated sintered steel under cyclic loading / Al Emran Ismail
Full text linkFatigue crack nucleation and initiation at particles or defects in materials have been the interest of many researchers over the past years . This is because the understanding of theses phenomena would provide a better understanding of production of new fatigue resistanc e materials. In this study a test was developed to evaluate the fatigue properties and to observe fatigue crack nucleation and initiation in sintered steel. The fatigue test was carried out on polished specimens which was based on plate bending gives balanced biaxial tension. The experimental results shows that there were mixed mode of crack nucleation and initiation such that most cracks initiated at the interface of particles and matrix especially at high stress values . Cracks were also observed to initiate at voids and beneath the surface. Quenched specimens which were tempered between temperature range of 300°C and 600°C shows similar crack initiation mechanisms. The significant differenc e between as-rece ived and tempered specimens was that the number of cycles to fail due to di fferences in material hardne ss and internal defect s. The result s of the experimentation are discussed in the light of possible micro crack toughening at the crack tip and the presence of residual stresses due, to temperature changes. It is believed that some effects of residual stresses at the surface and beneath playa role in the nucleation of crack in sinter ed steel
Mode III stress intensity factors of sickle-shaped surface cracks in round bars / Al Emran Ismail
No full textThe solutions of stress intensity factors (SIFs) of sickle-shaped surface crack in round bars are not currently available especially when the cracks are subjected to mode III loading. Mode I SIFs can be obtained in open literature however they are also insufficiently completed. Therefore, this paper develops numerically the sickle-shaped crack in round bars using AN SYS finite element program. In order to validate the model, the existing mode I SIFs are used and then compared with the present model. It is found that both models are well agreed with each other. There are two important parameters used such as the crack aspect ratio, a/b and the relative crack depth, a/D ranging between 0.2-1.2 and 0.1-0.6, respectively. SIFs based on J-integral are calculated along the crack fronts for various crack geometries. It is found that the SIFs are significantly affected by a/b and a/D. For the relatively straight-fronted crack (a/b £ 0.2), the SIFs are almost flattened along the crack front. When a/b increased (a/b > 0.2), the SIFs have decreased whereas they are increased when a/D increased. It is also found that the SIFs closed to the outer edge are higher than the SIFs at the deepest crack along the crack front. However when a/b³ 1.2, the role of SIFs along the crack fronts are inversed where lower SIFs are observed at the outer point compared with the middle point
A review of the metaverse in higher education: opportunities, challenges and future research agenda
No full textThis study explores the implications of the metaverse from four distinct perspectives: technology, students, lecturers, and pedagogy. From the technology standpoint, we investigate the optimization of user experience design, technical limitations, accessibility, integration with existing educational technologies, the role of advanced natural language processing, machine learning, and data analytics in supporting personalized and adaptive learning experiences. Moreover, we delve into the student perspective, considering the potential impact of the metaverse on accessibility, inclusivity, and student satisfaction. We also assess the potential for personalized learning experiences, skill development, and student autonomy within the metaverse. From the lecturer’s perspective, we discuss the opportunities and challenges associated with transitioning to metaverse-based teaching, emphasizing the importance of professional development and support for educators. We examine the pedagogical benefits of metaverse-based education, highlighting how immersive and interactive learning experiences can promote deeper understanding, engagement, and motivation. Finally, the paper outlines a comprehensive research agenda that addresses the opportunities and challenges of implementing the metaverse in teaching and learning. By examining the metaverse from these diverse perspectives, this study contributes to the growing body of literature on the fusion of innovative technologies in education, providing valuable insights for technologists, educators, researchers, and policymakers
A Review of The Metaverse in Higher Education: Opportunities, Challenges and Future Research Agenda
No full textThis study explores the implications of the metaverse from four distinct perspectives: technology, students, lecturers, and pedagogy. From the technology standpoint, we investigate the optimization of user experience design, technical limitations, accessibility, integration with existing educational technologies, the role of advanced natural language processing, machine learning, and data analytics in supporting personalized and adaptive learning experiences. Moreover, we delve into the student perspective, considering the potential impact of the metaverse on accessibility, inclusivity, and student satisfaction. We also assess the potential for personalized learning experiences, skill development, and student autonomy within the metaverse. From the lecturer’s perspective, we discuss the opportunities and challenges associated with transitioning to metaverse-based teaching, emphasizing the importance of professional development and support for educators. We examine the pedagogical benefits of metaverse-based education, highlighting how immersive and interactive learning experiences can promote deeper understanding, engagement, and motivation. Finally, the paper outlines a comprehensive research agenda that addresses the opportunities and challenges of implementing the metaverse in teaching and learning. By examining the metaverse from these diverse perspectives, this study contributes to the growing body of literature on the fusion of innovative technologies in education, providing valuable insights for technologists, educators, researchers, and policymakers
Fatigue crack initiation in powder metallurgically-processed tool steel material under cyclic loading / Al Emran Ismail and Mohd Nor Berhan
Full text linkThe cyclic behavior of P/M steel has been evaluated at different tempering conditions. Heat treatment is found to significantly affect the hardness, micro structure and fatigue response of the material. Optimum tempering temperature is found to give the highest hardness and better fatigue life compare to as-received material. This heat treatment also characterizes the mechanisms of fatigue crack initiations. Three mechanisms are found in this material: (I) crack initiated from broken particle, (2) crack initiated from open pore and (3) crack initiated from interfacial debonding between particle and matrix. It has been observed that, by carefully designing the heat treatment this steel can be beneficially used in fatigue loaded components
Examining the Use of Generative Artificial Intelligence in Higher Education and Its Impact on Social Sustainability: An Integrated Model of UTAUT2 and T-EESST
No full textIn this research, the author assesses and evaluates the degree to which the higher education (HE) sector has embraced generative artificial intelligence (GenAI), primarily focusing on the adoption and application of GenAI and its implications for social sustainability. The aim of this research entails the proposing and advancing of a model that enhances the adoption of GenAI in an educational setting that is based on Technology-Environmental, Economic, and Social Sustainability Theory (T-EESST) and the extended Unified Theory of Acceptance and Use of Technology (UTAUT2) model. This research employs structural equation modelling (SEM), in conjunction with artificial neural networks (ANNs), to examine the main constructs driving the intention to use GenAI and the nature of its impact on social sustainability (SS). The research’s results indicate four factors that significantly impact the adoption of GenAI in HE—habit (HB), hedonic motivation (HM), performance expectancy (PE), and perceived trust (PT)—essentially highlighting intrinsic motivators. However, effort expectancy (EE), social influence (SI), facilitating conditions (FC), price value (PV), and perceived risk (PR) were not statistically significant. Furthermore, the study demonstrates that adopting GenAI has a significant impact on social sustainability (SS) in education by promoting equitable, inclusive, and lifelong learning, as well as enhancing societal well-being. These outcomes provide essential awareness for policymakers and educational institutions, establishing a basis for developing socially sustainable learning environments that leverage the revolutionary capabilities of GenAI.
Keywords: Generative AI, higher education, technology acceptance, UTAUT2, T-EESST, SEM, ANN, habit, hedonic motivation, perceived trust, social sustainability, perceived risk, performance expectancy, effort expectancy
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