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Green roof benefits, opportunities and challenges – A review
Shafique, Muhammad,Kim, Reeho,Rafiq, Muhammad Elsevier 2018 RENEWABLE & SUSTAINABLE ENERGY REVIEWS Vol.90 No.-
<P><B>Abstract</B></P> <P>Research on the green roof has been raised expeditiously over the past decade. Green roof have been proposed as the sustainable practice to mitigate the adverse effects of urbanization. This review paper includes the history of the green roof, green roof components and multiple benefits (environmental, social and economical) associated with the green roof technology. This paper also emphasizes how the green roof works in different areas, their performance in reducing the stormwater and energy costs, improving air and ecological performance. The benefits of green roof show that it plays an important role in making cities safe, sustainable and resilient to climate change. Therefore, many countries are giving incentives to the house owners for the application of green roof. However, initial high construction costs, high maintenance costs and roof leakage problems are the main challenges associated with the application of green roofs. These challenges can be overcome with the of new cost effective green roof design that can work more effectively and efficiently in any area. Advanced modification and trends of green roof application are also included in this paper. The paper also highlights the research challenges and research gap of the green roof. At the end, for the better performance of the green roofs, some of the recommendations are also provided.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Significance of green roof practices is illustrated. </LI> <LI> Green roof function and its main components are summarized. </LI> <LI> Green roof benefits, challenges and research gap are reviewed and explained. </LI> <LI> Potential research and development opportunities are identified. </LI> </UL> </P>
Effect of the thickness on the mixed mode crack front fields
Shafique M.A. Khan 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.42 No.5
Results pertaining to 3D investigations on the effect of the thickness on the stress fields at the crack front are presented. A 3D finite element analysis is performed using a modified single edgenotched tension specimen configuration, with an inclined crack to include mixed mode I-II. A technique to mesh the crack front (3D) with singular finite elements in ANSYS without using third party software is introduced and used in this study. The effect of the specimen thickness is explicitly investigated for six thicknesses ranging from 1 to 32 mm. In addition, three crack inclination angles, including pure Mode-I, are used to study the effect of mixed-mode I-II fracture. An attempt is made to correlate the extent of a particular stress state along the crack front to thickness. In addition, σzz /ν (σxx + σyy) contours at the crack front are presented as a useful means to analyze the stress state.
Structural and mechanical properties of friction stir welded Al2O3 and SiC reinforced Al 7075 alloys
Jarair Shafique,Hussein Alrobei,Aneela Wakeel,Rizwan Ahmed Malik,Azhar Hussain,Jaehwan Kim,무하마드 라티프 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.4
Al 7075 of 4 mm thickness plates were welded by using ceramic particles of micron size. Different revolution speed, ranging from 1600 to 2000 RPM and transverse speed of 17 to 35 mm/min were applied. The sound weld is achieved at revolution speed of 1600 RPM and transverse speed of 17 mm/min. In this work, ceramic particles of Al 2 O 3 and SiC were used to reduce the effect of the heat towards the base material during friction stir welding owing to their high friction coefficient and reasonable thermal conductivity and to enhance mechanical properties. Vickers microhardness test was performed on the plain, Al 2 O 3 , and SiC mixed Al 7075 welded samples. This test showed the welded joint by using Al 2 O 3 and SiC have 10 to 12 % increase in hardness than that of the joint without using particles. Tensile strength of welded joints without ceramics particles showed improved results. Dispersion of ceramics particles was examined by metallurgical microscope. Scanning electron microscope (SEM) images and fracture analysis of the stir welded zone and base materials were observed. The structuralproperty relationship of plain, Al 2 O 3 , and SiC mixed Al 7075 welded samples was discussed systematically and found that improvement in hardness for Al 2 O 3 , and SiC mixed Al 7075 welded samples was due to the higher thermal conductivities of added ceramic particles and precipitation strengthening mechanism. While, reduction in tensile strength ascribed to the formation of intermetallic compounds.
Effect of the thickness on the mixed mode crack front fields
Khan, Shafique M.A. Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.42 No.5
Results pertaining to 3D investigations on the effect of the thickness on the stress fields at the crack front are presented. A 3D finite element analysis is performed using a modified single edge-notched tension specimen configuration, with an inclined crack to include mixed mode I-II. A technique to mesh the crack front (3D) with singular finite elements in ANSYS without using third party software is introduced and used in this study. The effect of the specimen thickness is explicitly investigated for six thicknesses ranging from 1 to 32 mm. In addition, three crack inclination angles, including pure Mode-I, are used to study the effect of mixed-mode I-II fracture. An attempt is made to correlate the extent of a particular stress state along the crack front to thickness. In addition, ${\sigma}_{zz}/{\nu}({\sigma}_{xx}+{\sigma}_{yy})$ contours at the crack front are presented as a useful means to analyze the stress state.