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Effect of Elevated Temperature on Mechanical Properties of Limestone, Quartzite and Granite Concrete
Tufail, Muhammad,Shahzada, Khan,Gencturk, Bora,Wei, Jianqiang Korea Concrete Institute 2017 International Journal of Concrete Structures and M Vol.11 No.1
Although concrete is a noncombustible material, high temperatures such as those experienced during a fire have a negative effect on the mechanical properties. This paper studies the effect of elevated temperatures on the mechanical properties of limestone, quartzite and granite concrete. Samples from three different concrete mixes with limestone, quartzite and granite coarse aggregates were prepared. The test samples were subjected to temperatures ranging from 25 to $650^{\circ}C$ for a duration of 2 h. Mechanical properties of concrete including the compressive and tensile strength, modulus of elasticity, and ultimate strain in compression were obtained. Effects of temperature on resistance to degradation, thermal expansion and phase compositions of the aggregates were investigated. The results indicated that the mechanical properties of concrete are largely affected from elevated temperatures and the type of coarse aggregate used. The compressive and split tensile strength, and modulus of elasticity decreased with increasing temperature, while the ultimate strain in compression increased. Concrete made of granite coarse aggregate showed higher mechanical properties at all temperatures, followed by quartzite and limestone concretes. In addition to decomposition of cement paste, the imparity in thermal expansion behavior between cement paste and aggregates, and degradation and phase decomposition (and/or transition) of aggregates under high temperature were considered as main factors impacting the mechanical properties of concrete. The novelty of this research stems from the fact that three different aggregate types are comparatively evaluated, mechanisms are systemically analyzed, and empirical relationships are established to predict the residual compressive and tensile strength, elastic modulus, and ultimate compressive strain for concretes subjected to high temperatures.
A Survey on 5G Enabled Multi-Access Edge Computing for Smart Cities: Issues and Future Prospects
Tufail, Ali,Namoun, Abdallah,Alrehaili, Ahmed,Ali, Arshad International Journal of Computer ScienceNetwork S 2021 International journal of computer science and netw Vol.21 No.6
The deployment of 5G is in full swing, with a significant yearly growth in the data traffic expected to reach 26% by the year and data consumption to reach 122 EB per month by 2022 [10]. In parallel, the idea of smart cities has been implemented by various governments and private organizations. One of the main objectives of 5G deployment is to help develop and realize smart cities. 5G can support the enhanced data delivery requirements and the mass connection requirements of a smart city environment. However, for specific high-demanding applications like tactile Internet, transportation, and augmented reality, the cloud-based 5G infrastructure cannot deliver the required quality of services. We suggest using multi-access edge computing (MEC) technology for smart cities' environments to provide the necessary support. In cloud computing, the dependency on a central server for computation and storage adds extra cost in terms of higher latency. We present a few scenarios to demonstrate how the MEC, with its distributed architecture and closer proximity to the end nodes can significantly improve the quality of services by reducing the latency. This paper has surveyed the existing work in MEC for 5G and highlights various challenges and opportunities. Moreover, we propose a unique framework based on the use of MEC for 5G in a smart city environment. This framework works at multiple levels, where each level has its own defined functionalities. The proposed framework uses the MEC and introduces edge-sub levels to keep the computing infrastructure much closer to the end nodes.
Effects of cursor freeze time on the performance of older adult users on mouse-related tasks
Tufail, Muhammad,Kim, KwanMyung Elsevier 2017 Applied ergonomics Vol.65 No.-
<P><B>Abstract</B></P> <P>This study determines the optimum range of cursor freeze time (CFT) for basic target acquisition tasks. The effect of five levels of CFT was measured on double-clicking, clicking, and drag-and-drop operations, along with the inconvenience perceived by users at these levels. Older adult users find these standard mouse operations challenging because of slipping and accidental cursor movement. In this study, 24 older adult participants (13 males and 11 females) performed the abovementioned tasks repeatedly across five levels of CFT (0, 200, 400, 600, and 800 ms) and rated their perceived inconvenience at each level. CFT was found to have a significant effect on the three basic target acquisition tasks as well as the inconvenience perceived by participants. Performance on the drag-and-drop task was negatively influenced when the CFT was increased from 600 to 800 ms. The analysis suggests that a CFT of 200–400 ms is the optimum range for improved performance on the tasks.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Older adult users performed three mouse-related tasks at five levels of CFT. </LI> <LI> CFT varyingly influenced task performance and perceived inconvenience. </LI> <LI> The results suggest an optimum range of 200–400 ms for successful mouse tasks. </LI> </UL> </P>
Effect of Elevated Temperature on Mechanical Properties of Limestone, Quartzite and Granite Concrete
Muhammad Tufail,Khan Shahzada,Bora Gencturk,Jianqiang Wei 한국콘크리트학회 2017 International Journal of Concrete Structures and M Vol.11 No.1
Although concrete is a noncombustible material, high temperatures such as those experienced during a fire have a negative effect on the mechanical properties. This paper studies the effect of elevated temperatures on the mechanical properties of limestone, quartzite and granite concrete. Samples from three different concrete mixes with limestone, quartzite and granite coarse aggregates were prepared. The test samples were subjected to temperatures ranging from 25 to 650 『C for a duration of 2 h. Mechanical properties of concrete including the compressive and tensile strength, modulus of elasticity, and ultimate strain in compression were obtained. Effects of temperature on resistance to degradation, thermal expansion and phase compositions of the aggregates were investigated. The results indicated that the mechanical properties of concrete are largely affected from elevated temperatures and the type of coarse aggregate used. The compressive and split tensile strength, and modulus of elasticity decreased with increasing temperature, while the ultimate strain in compression increased. Concrete made of granite coarse aggregate showed higher mechanical properties at all temperatures, followed by quartzite and limestone concretes. In addition to decomposition of cement paste, the imparity in thermal expansion behavior between cement paste and aggregates, and degradation and phase decomposition (and/or transition) of aggregates under high temperature were considered as main factors impacting the mechanical properties of concrete. The novelty of this research stems from the fact that three different aggregate types are comparatively evaluated, mechanisms are systemically analyzed, and empirical relationships are established to predict the residual compressive and tensile strength, elastic modulus, and ultimate compressive strain for concretes subjected to high temperatures.