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Earthquake Engineering and Engineering Vibration 2013年第3期12卷 385-397页

作者： Mohammad AlHamaydeh Khaled Galal sherif yehia Department of Civil Engineering American University of SharjahSharjah UAE Department of Building Civil & Environmental Engineering Concordia UniversityMontréal Québec Canada

The local design and construction practices in the United Arab Emirates （UAE）, together with Dubai＇s unique rate of development, warrant special attention to the selection of Lateral Force-Resisting Systems （LFRS）. This research proposes four different feasible solutions for the selection of the LFRS for tall buildings and quantifies the impact of these selections on seismic performance and cost. The systems considered are： Steel Special Moment-Resisting Frame （SMRF）, Concrete SMRF, Steel Dual System （SMRF with Special Steel Plates Shear Wall, SPSW）, and Concrete Dual System （SMRF with Special Concrete Shear Wall, SCSW）. The LFRS selection is driven by seismic setup as well as the adopted design and construction practices in Dubai. It is found that the concrete design alternatives are consistently less expensive than their steel counterparts. The steel dual system is expected to have the least damage based on its relatively lesser interstory drifts. However, this preferred performance comes at a higher initial construction cost. Conversely, the steel SMRF system is expected to have the most damage and associated repair cost due to its excessive flexibility. The two concrete alternatives are expected to have relatively moderate damage and repair costs in addition to their lesser initial construction cost.

关键词： special moment-resisting frames (SMRF) special shear wall Dubai, UAE seismicity steel concrete dual system

Performance of Structures Exposed to Extreme High Temperature—An Overview

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Open Journal of Civil Engineering 2013年第3期3卷 154-161页

作者： sherif yehia Ghanim Kashwani Department of Civil Engineering American University of Sharjah Sharjah UAE

Strength, durability and stability are the main criteria for material selection and design in the construction industry. Consequently, development and enhancement of construction materials is always an active and attractive field for engineers and researchers. Elevated temperature (fire) is a potential threat for any structural buildings that can cause a major damage. Response of construction materials exposed to elevated temperature or fire requires a full study and analysis with lessons learned from previous cases. In this paper, properties of the common construction materials such as concrete, steel and composite structures under high temperature events is presented and discussed. In addition, performance of advanced materials, such as Fiber Reinforced Polymer (FRP) and Concrete Filled Tubular (CFT) when exposed to high temperature was discussed. Recommendations from different design codes to increase fire resistance of structures are introduced. Finally, damage assessment of several bridges and buildings found in the literature exposed to fire events is summarized.

关键词： Construction Material Fire Resistance Impact of Fire on Structures Structural Performance

Utilization of Recycled Coarse Aggregate in Concrete Mixes

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Journal of Civil Engineering and Architecture 2011年第6期5卷 562-566页

作者： Akmal Abdelfatah Sami Tabsh sherif yehia Civil Engineering Department American University of Sharjah UAE

In this paper, the effect of the source of recycled coarse aggregate on the properties of concrete is investigated. The tests were conducted on concrete made from three sources of recycled aggregates：（1） old concrete with unknown strength, （2） old concrete with a known compressive strength of 21 MPa, and （3） old concrete with a known strength of 42 MPa. The three sources of recycled aggregates were used to produce new concrete with a target compressive strength of 21 MPa. The first and third sources of recycled aggregates were used in producing concrete with target strength of 42 MPa. A control mix was designed with aggregates from natural sources. The research included two methods of making recycled concrete. One concrete mix was produced using the recycled aggregate and adding more water than the control mix, to reach the target slump, while the second concrete mix was produced using the same amount of water as the control mix but with additional superplasticizer to maintain the target slump. The results obtained in this research showed that the concrete compressive strength depends on the source of recycled aggregates; the stronger the source of recycled aggregate, the higher the compressive strength of the produced concrete. Furthermore, the compressive strength of the first concrete mix was about 10%-20% lower than the compressive strength of the control mix. However, when superplasticizers were used, the compressive strength was around the same value as the control mix.

关键词： Compressive strength concrete environment recycled concrete.

Magnetic Properties and Electronic Structure of ThCo<sub>4</sub>B

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Modeling and Numerical Simulation of Material Science 2012年第3期2卷 51-59页

作者： Mohammed Said Mohammed Abu-Elmagd Samy Hashim Aly sherif yehia Physics Faculty of Science at Damietta Mansoura University New Damietta Egypt Physics Faculty of Science Helwan University Cairo Egypt Physics Higher Institute of Engineering Shourok Academy Cairo Egypt

We present density functional theory DFT ab initio calculation of the electronic and magnetic properties of ThCo4B compound using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method as implemented in the Wien2k package. The influence of the local environment on the Co magnetic moments is discussed by comparing the magnetic and electronic properties of ThCo4B to its parent ThCo5 compound. The total magnetic moment in these two compounds is dominated by the Co moment. The Spin orbit interaction affects the electronic structure and spin-density maps of the p-state of Th.

关键词： ThCo4B Electronic Structure Spin Density Map

Thermal decomposition of ammonium perchlorate catalyzed with CuO nanoparticles

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Defence Technology（防务技术） 2019年第6期15卷 868-874页

作者： sherif Elbasuney M.yehia Head of Nanotechnology Research Center School of Chemical EngineeringMilitary Technical College

Ammonium perchlorate(APC)is the most common oxidizer in use for solid rocket propulsion *** its initial thermal decomposition is an endothermic process that requires 102.5 J·g^-*** manner involves high activation energy and could render high burning rate *** study reports on the sustainable fabrication of CuO nanoparticles as a novel catalyzing agent for APC *** CuO nanoparticles with consistent product quality were fabricated by using hydrothermal *** micrographs demonstrated mono-dispersed particles of 15 nm particle *** diffractogram demonstrated highly crystalline *** synthesized colloidal CuO particles were effectively coated with APC particles via co-precipitation by using fast-crash solvent-antisolvent *** impact of copper oxide particles on APC thermal behavior has been investigated using DSC and TGA *** demonstrated an initial endothermic decomposition stage at 242℃ with subsequent two exothermic decomposition stages at 297,8℃ and 452.8℃ *** 1 wt%,copper oxide offered decrease in initial endothermic decomposition stage by 30%.The main outcome of this study is that the two main exothermic decomposition peaks were merged into one single peak with an increase in total heat release by 53%.These novel features can inherit copper oxide particles unique catalyzing ability for advanced highly energetic systems.

关键词： Ammonium perchlorate Catalyst Thermal behavior Energetic systems Catalyzed propellants

Thermochemical Aspects of Activated Ammonium Perchlorates with Superior Thermal Stability,Decomposition Enthalpy,Propagation Index,and Decomposition Kinetic Parameters

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Journal of Thermal Science 2021年第6期30卷 2196-2201页

作者： sherif Elbasuney M.yehia SHUKRI Ismael sherif Farag AHMED Saleh GHARIEB S.El-Sayyad Head of Nanotechnology Research Center Military Technical College(MTC)Cairo 11646Egypt School of Chemical Engineering Military Technical College(MTC)Cairo 11646Egypt Science and Technology Center of Excellence Cairo 11646Egypt Drug Radiation Research Department National Center for Radiation Research and Technology(NCRRT)Egyptian Atomic Energy Authority(EAEA)Cairo 11646Egypt

Ammonium perchlorate(AP)includes oxidizing and reducing elements on the same *** can act as an efficient oxidizer and mono-propellant as *** this study,AP experienced crystallographic phase change from orthorhombic centrosymmetric to non-centrosymmetric under controlled isothermal heat *** diffractograms confirmed this crystallographic phase *** thermal behaviour of activated AP had been investigated using *** AP demonstrated high chemical stability with an increase in endothermic phase transition enthalpy by 170%.The enthalpy of the subsequent two main exothermic decomposition reactions was increased by 250%.Whereas AP demonstrated total decomposition enthalpy of 733 J/g,activated AP showed 2614 J/*** AP can secure self-sustained response at a high *** index(combustion enthalpy/ignition temperature)was employed to assess self-sustained reaction *** AP demonstrated high propagation index of 8.7 compared with 2.5 for un-activated *** decomposition kinetic parameters had investigated using Kissinger and KAS *** AP showed an increase in activation energy by 89%using the Kissinger method;kinetic parameters using the KAS method were in good agreement with the Kissinger *** can have concluded that AP with novel kinetic decomposition parameters for enhanced safety storage and high combustion characteristics has evolved.

关键词： solid propellants oxidizers thermal behavior Kinetic parameters activation energy

Continuous hydrothermal synthesis of AlO(OH)nanorods as a clean flame retardant agent

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Particuology 2015年第5期13卷 66-71页

作者： sherif Elbasuney School of Chemical Engineering Military Technical College

Aluminum-oxide-hydroxide （AIOOH） is a clean and non-toxic flame retardant. There have been many trials for the fabrication of ultrafine AIOOH, Two main approaches exist for nano-AlOOH synthesis： reactive precipitation and batch hydrothermal synthesis, Both approaches are laborious and time consuming with poor control of particle morphology. We report on the novel continuous flow manufacture of AIOOH nanorods with controlled morphology （particle size and shape） by hydrothermal synthesis. AIOOH was harvested from its mother liquor （colloidal solution） using poly（acrylamide-co-acrylic acid） copolymer as a flocculating agent. The developed AIOOH shape and size, crystalline phase, thermal stability, and endothermic heat sink action were investigated by transmission electron microscopy, X-ray diffractome- try, thermogravimetric analysis, and differential scanning calorimetry, respectively. The phase transition of AlOOH to Al2O3 was demonstrated by conducting different X-ray diffractometry scans from 400 to 700℃. These results may provide an option for the continuous synthesis of nano-AIOOH as a clean and non-toxic flame retardant with excellent thermal stability. Consequently, enhanced flammability properties can be achieved at low solids loading.

关键词： Flame retardants Hydrated minerals Hydrothermal synthesis

New design simulation for a high-altitude dual-balloon system to extend lifetime and improve floating performance

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Chinese Journal of Aeronautics 2018年第5期31卷 1109-1118页

作者： sherif SALEH Weiliang HE Aviation and Aerospace Science Division Military Technical College School of Astronautics Beihang University

This paper presents a comprehensive simulation for a high-altitude dual-balloon system which consists of zero-and super-pressure balloons. Preliminary calculations were established to describe the basic concept of the new integrated system. A mathematical model was investigated to simulate the ascending and floating processes which considered the atmospheric conditions and thermodynamic variations. Based on the simulation, results showed that the floating altitude stability between daytime and nighttime was improved. This integrated system supports higher floating altitude levels than those of ordinary balloons and extends the lifetime of floating balloon systems. Moreover, results demonstrated that the integrated system was lighter than ordinary balloons, saving useful weight for effective payload. Furthermore, exploiting the advantages of both kinds of balloons while avoiding the difficulties was a significant goal in the current design to promote the floating performance of high-altitude balloons technology.

关键词： Altitude stability Ascending trajectory Compressor performance High altitude balloons Long endurance

A focus on parietal cells as a renewing cell population

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World Journal of Gastroenterology 2010年第5期16卷 538-546页

作者： sherif M Karam Department of Anatomy Faculty of Medicine and Health Sciences United Arab Emirates University Al-Ain PO Box 17666 United Arab Emirates

The fact that the acidsecreting parietal cells undergo continuous renewal has been ignored by many gastroenterologists and cell biologists. In the past, it was thought that these cells were static. However, by using 3Hthymidine radioautography in combination with electron microscopy, it was possible to demonstrate that parietal cells belong to a continuously renewing epithelial cell lineage. In the gastric glands, stem cells anchored in the isthmus region are responsible for the production of parietal cells. The stem cells give rise to three main progenitors: prepit, preneck and preparietal cells. Parietal cells develop either directly from the noncycling preparietal cells or less commonly via differentiation of the cycling prepit and preneck cell progenitors. The formation of a parietal cell is a sequential process which involves diminishment of glycocalyx, production of cytoplasmic tubulovesicles, an increase in number and length of microvilli, an increase in number and size of mitochondria, and fi nally, expansion and invagination of the apical membrane with the formation of an intracellular canalicular system. Little is known about the genetic counterparts of these morphological events. However, the time dimension of parietal cell production and the consequences of its alteration on the biological features of the gastric gland are well documented. The production of a new parietal cell takes about 2 d. However, mature parietal cells have a long lifespan during which they migrate bidirectionally while their functional activity for acid secretion gradually diminishes. Following an average lifespan of about 54 d, in mice, old parietal cells undergo degeneration and elimination. Various approaches for genetic alteration of the development of parietal cells have provided evidence in support of their role as governors of the stem/progenitor cell proliferation and differentiation programs. Revealing the dynamic features and the various roles of parietal cells would help

关键词： Cell differentiation Cell dynamics Cell renewal Oxyntic gland Oxyntic mucosa Parietal cell Preparietal cell

Efficient Relational Techniques for Processing Graph Queries

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Journal of Computer Science & Technology 2010年第6期25卷 1237-1255页

作者： sherif Sakr Ghazi Al-Naymat School of Computer Science and Engineering University of New South Wales Managing Complexity Group National ICT Australia (NICTA)

Graphs are widely used for modeling complicated data such as social networks,chemical compounds,protein interactions and semantic *** effiectively understand and utilize any collection of graphs,a graph database that efficiently supports elementary querying mechanisms is crucially *** example,Subgraph and Supergraph queries are important types of graph queries which have many applications in practice.A primary challenge in computing the answers of graph queries is that pair-wise comparisons of graphs are usually hard *** database management systems（RDBMSs） have repeatedly been shown to be able to efficiently host different types of data such as complex objects and XML *** derive much of their performance from sophisticated optimizer components which make use of physical properties that are specific to the relational model such as sortedness,proper join ordering and powerful indexing *** this article,we study the problem of indexing and querying graph databases using the relational *** present a purely relational framework for processing graph *** framework relies on building a layer of graph features knowledge which capture metadata and summary features of the underlying graph *** describe different querying mechanisms which make use of the layer of graph features knowledge to achieve scalable performance for processing graph ***,we conduct an extensive set of experiments on real and synthetic datasets to demonstrate the efficiency and the scalability of our techniques.

关键词： graph database graph query subgraph query supergraph query