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Effect of rebar spacing on the behavior of concrete slabs under projectile impact
Husain Abbas,Nadeem A. Siddiqui,Tarek H. Almusallam,Aref A. Abadel,Hussein Elsanadedy,Yousef A. Al-Salloum 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.3
In this paper, the effect of different steel bar configurations on the quasi-static punching and impact response of concrete slabs was studied. A total of forty RC square slab specimens were cast in two groups of concrete strengths of 40 and 63 MPa. In each group of twenty specimens, ten specimens were reinforced at the back face (singly reinforced), and the remaining specimens were reinforced on both faces of the slab (doubly reinforced). Two rebar spacing of 25 and 100 mm, with constant reinforcement ratio and effective depth, were used in both singly and doubly reinforced slab specimens. The specimens were tested against the normal impact of cylindrical projectiles of hemispherical nose shape. Slabs were also quasi-statically tested in punching using the same projectile, which was employed for the impact testing. The experimental response illustrates that 25 mm spaced rebars are effective in (i) decreasing the local damage and overall penetration depth, (ii) increasing the absorption of impact energy, and (iii) enhancing the ballistic limit of RC slabs. The ballistic limit was predicted using the quasi-static punching test results of slab specimens showing a strong correlation between the dynamic perforation energy and the energy required for quasi-static perforation of slabs.
Post-Heating Response of Concrete-Filled Circular Steel Columns
Husain Abbas,Yousef Al-Salloum,Saleh Alsayed,Mohammed Alhaddad,Rizwan Iqbal 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.4
Concrete-Filled Steel Tubular (CFST) columns are increasingly becoming popular for carrying heavy loads. One of the major concerns for such columns has always been the exposure to fire and subsequent cooling for which different methods are adopted. This study investigates the effect of cooling regimes after exposure to elevated temperature of 600oC for three hours on axial compression behavior of concrete-filled circular stub columns. The experimental program involves the testing of thirty columns consisting of two sizes of outer steel tube. Double skin columns were also considered for the bigger diameter column. The cooling regimes considered in the study were annealing and water quenching. The columns were tested for two possible modes of load transfer viz. core loaded and composite loaded. The behavior of columns was studied in terms of ultimate load capacity, loaddeformation pattern and stresses in the materials. The ductility of concrete-filled columns was higher than that of the steel tube alone. The confinement offered by outer steel tube was less in composite loaded columns as compared to core loaded columns. The annealing was found to be slightly better than water quenching for post-fire cooling of columns.
Allen Zhi,Abbas Husain 대한응급의학회 2019 Clinical and Experimental Emergency Medicine Vol.6 No.1
INTRODUCTION Free open access medical education (FOAM) applications (apps) enhance traditional reference modalities by exposing users to cutting edge concepts through a dynamic collection of visual and auditory resources which encourage collaboration, information sharing and knowledge translation.
Simone Rudnin,Josh Greenstein,Abbas Husain 대한응급의학회 2021 Clinical and Experimental Emergency Medicine Vol.8 No.1
Free open access medical education (FOAM) harnesses the power of various digital communication platforms such as websites, blogs, tweets, podcasts, videos, and social media applications. This online community contributes to sharing ideas and “accelerates the translation of research into clinical practice.”1 In this paper, we will explore the use of FOAM to learn and teach pointof-care ultrasound (POCUS) as images and videos of ultrasonography are easily posted and shared online with clinical vignettes and procedure descriptions.
A Visualization Based Analysis on Dynamic Bandwidth Allocation Algorithms for Optical Networks
Kamran Ali Memon,Khalid Husain Mohmadani,Saleemullah Memon,Muhammad Abbas,Noor ul Ain International Journal of Computer ScienceNetwork S 2023 International journal of computer science and netw Vol.23 No.8
Dynamic Bandwidth Allocation (DBA) methods in telecommunication network & systems have emerged with mechanisms for sharing limited resources in a rapidly growing number of users in today's access networks. Since the DBA research trends are incredibly fast-changing literature where almost every day new areas and terms continue to emerge. Co - citation analysis offers a significant support to researchers to distinguish intellectual bases and potentially leading edges of a specific field. We present the visualization based analysis for DBA algorithms in telecommunication field using mainstream co-citation analysis tool-CiteSpace and web of science (WoS) analysis. Research records for the period of decade (2009-2018) for this analysis are sought from WoS. The visualization results identify the most influential DBA algorithms research studies, journals, major countries, institutions, and researchers, and indicate the intellectual bases and focus entirely on DBA algorithms in the literature, offering guidance to interested researchers on more study of DBA algorithms.
Saeed Ullah,Munawar Abbas,Saad Tariq,Khalid Mujasam Batoo,Nasir Rahman,Uzma Gul,Mudasser Husain,Sajjad Hussain,Mohamed Musa Saad Hasb Elkhalig,Muhammad Usman Ghani 한국전기전자재료학회 2024 Transactions on Electrical and Electronic Material Vol.25 No.3
In this study, a theoretical investigation employing the Wien2k package within DFT framework was conducted to inspect mechanical, structural, and optoelectronic properties of silver-based cubic chloro-perovskites QAgCl 3 . Stability of these compounds was confi rmed by fi tting optimized data to Birch Muranghan equation, enthalpy of formation and tolerance factor. The mBJ potential was utilized to compute band profi les, revealing semiconducting nature mainly from Ag d-states and Cl p-states. Born-Huang criteria confi rmed mechanical stability, while other elastic parameters indicated ionic bonding, anisotropy, stiff ness, ductility, fracture resistance, and bond-bending resistance. Optical study suggested suitability for practical optoelectronic devices, with a lack of absorbance in the visible region. These outcomes off er a platform for further experimental and theoretical research.
Shahid Muhammad Bilal,Jin Weidong,Abbasi Muhammad Abbas,Husain Abdul Rashid,Hassan Mannan 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3
Weighting factor design is considered a challenging and tedious task in finite control set model predictive torque control (FCS-MPTC) for induction motor drives. The complexity involved in designing the weighting factor occurs due to the presence of different quantities in the cost function. In the absence of an accurate design method, a constant weighting factor is used for entire operating range of the drive which does not guarantee optimal performance. To improve the performance of the MPTC, an online tuning method for the weighting factor is proposed in this work. The tuning process is achieved by comparing torque error to predefined threshold value at any given sampling instant. If the error is larger than the threshold limit, weighting factor is increased to bring the error within the acceptable limit and vice versa. In each sampling interval, the cost function is optimized with the tuned weighting factor and optimal voltage vector is chosen. The effectiveness of the proposed method is validated experimentally for a two level three-phase inverter-fed induction motor drive on dSpace DS1104 controller board. The performance of the proposed method is compared to the conventional MPTC with fixed weighting factor and an online weighting factor tuning method based on the principle of coefficient-of-variation (CV-MPTC). It is concluded that the proposed method not only improves dynamic performance of the drive as compared to both methods but also offers computational advantages over CV-MPTC.
Effect of molar ratios on strength, microstructure & embodied energy of metakaolin geopolymer
Abadel, Aref A.,Albidah, Abdulrahman S.,Altheeb, Ali H.,Alrshoudi, Fahed A.,Abbas, Husain,Al-Salloum, Yousef A. Techno-Press 2021 Advances in concrete construction Vol.11 No.2
In this study, twenty-five geopolymer (GP) mixes were prepared by varying the alkaline solids to Metakaolin (MK) and sodium silicate to NaOH ratios from 0.1 to 0.5 and 0.2 to 1.0, respectively, thus giving a wide range of molar ratios of silica to alumina, sodium oxide to alumina and water to sodium oxide. The compressive strength of these GP mixes was determined for four curing schemes involving oven curing at 100℃ for 24 h and three ambient curing with the curing ages of 3, 14, and 28 days. The test results revealed that for the manufacture of GP binder for structural applications of strength up to 90 MPa, the molar ratio of silica to alumina should be greater than 2.3, sodium oxide to alumina should be between 0.6 to 1.2, and water to sodium oxide should not exceed 12. The compressive strength of ambient cured GP mortar gets stabilized at 28 days of ambient curing. Experimental findings were also corroborated by GP microstructure analysis. The embodied energy of MK-based GP mortars, especially of high strength, is significantly less than the cement mortar of equivalent strength.
Reliability Assessment of HFRC Slabs Against Projectile Impact
Nadeem A. Siddiqui,Yousef A. Al?Salloum,Tarek H. Almusallam,Aref A. Abadel,Husain Abbas 한국콘크리트학회 2018 International Journal of Concrete Structures and M Vol.12 No.6
In the present study, a probabilistic procedure is presented for estimating the reliability of hybrid fiber reinforced concrete (HFRC) slabs against the impact of hemispherical nose projectiles considering uncertainties involved in the material, geometric and impact parameters. The influence of hybrid fibers in improving the safety level of reinforced concrete slabs against impact loads has also been studied on a parametric basis. The failure of the HFRC slabs was assumed to occur when the impact velocity of the projectile exceeds the ballistic limit of the slab i.e. perforates the slab. To illustrate the procedure, a probabilistic analysis was carried out on the impact test results of HFRC slabs containing different proportions of hooked-end steel, polypropylene and Kevlar fibers, recently published by the authors. Reliability assessment was performed for a range of applied nominal impact loads by varying the impact velocity of the given projectile. Reliability analysis yields the safety level of all the HFRC slabs against the impact of the above projectile. Effect of fibers, especially steel fibers, and slab thickness on the reliability of HFRC slabs are also investigated on a parametric basis.
Nizwaside: a new anticancer pregnane glycoside from the sap of Desmidorchis flava
Hidayat Hussain,Ahmed Al-Harrasi,Muhammad Adil Raees,Najeeb Ur Rehman,Ahmed Al-Rawahi,Rene´ Csuk,Husain Yar Khan,Ghulam Abbas,Mohammed Abdullah Al-Broumi,Ivan R. Green,Ali Elyassi,Talat Mahmood 대한약학회 2015 Archives of Pharmacal Research Vol.38 No.12
The sap from the succulent Desmidorchis flava (N.E.Br) Meve and Liede yielded a new pregnane glycoside, named nizwaside whose structure was established using 1D and 2D NMR techniques as well as mass spectrometry (ESIMS). Nizwaside was tested for anticancer, DPPH antioxidant, urease enzyme inhibition, a-glucosidase enzyme inhibition and acetylcholinesterase inhibition activities. Interestingly, nizwaside showed significant anti-proliferative effects on MDA MB231 breast cancer cells with an IC50 of 23.5 lg/ml. Moreover, nizwaside was more effective than Doxorubicin, a wellknown clinical anticancer drug, in suppressing MDA MB231 cell proliferation even at concentrations lower than that of Doxorubicin (75 lg/ml nizwaside vs. 100 lg/ml Doxorubicin). On the other hand, nizwaside showed relatively weak antioxidant activity with 15 % inhibition.