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Stress distribution from railway track over geogrid reinforced ballast underlain by clay

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Earthquake Engineering and Engineering Vibration 2019年第1期18卷 77-93页

作者： mohammed Y.fattah Mahmood R.Mahmood mohammed f.Aswad Civil Engineering Department University of TechnologyBaghdad Iraq Civil Engineering Department University of TechnologyBaghdad IraqAssistant

Railway ballast forms a major component of a conventional rail track and is used to distribute the load to the subgrade, providing a smooth running surface for trains. It plays a significant role in providing support for the rail track base and distributing the load to the weaker layer underneath. Ballast also helps with drainage, which is an important factor for any type of transportation structure, including railroads. Over time, ballast progressively deforms and degrades under dynamic loading and loses its strength. In this study, extensive laboratory tests were conducted to investigate the effect of load amplitude, geogrid position, and number of geogrid layers, thickness of ballast layer and clay stiffness on the behavior of the reinforced ballast layer and induced strains in a geogrid. A half full-scale railway was constructed for carrying out the tests, which consisted of two rails 800 mm in length with three wooden sleepers(900 mm × 10 mm × 10 mm). Three ballast thicknesses of 200, 300 and 400 mm were used in the tests. The ballast was overlying 500 mm thickness clay in two states, soft and stiff. The tests were carried out with and without geogrid reinforcement; the tests were performed in a well-tied steel box of 1.5 m length ×1 m width ×1 m height. Laboratory tests were conducted to investigate the response of the ballast and the clay layers where the ballast was reinforced by a geogrid. Settlement in ballast and clay, soil pressure and pore water pressure induced in the clay were measured in reinforced and unreinforced ballast cases. It was concluded that the amount of settlement increased as the simulated train load amplitude increased, and there was a sharp increase in settlement up to cycle 500. After that, there was a gradual increase that leveled out between, 2500 to 4500 cycles depending on the frequency used. There was a slight increase in the induced settlement when the load amplitude increased from 0.5 to 1 ton but it was higher when the load am

关键词： ballast geogrid reinforcement clay stress pore water pressure dynamic load

Decoding molecular mechanisms:brain aging and Alzheimer's disease

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Neural Regeneration Research 2025年第8期20卷 2279-2299页

作者： Mahnoor Hayat Rafay Ali Syed Hammad Qaiser Mohammad Uzair Khalid Al-Regaiey Roaa Khallaf Lubna Abdullah mohammed Albassam Imdad Kaleem Xueyi Wang Ran Wang Mehwish SBhatti Shahid Bashir Atta-ur-Rahman School of Applied Biosciences(ASAB) National University of Sciences and Technology(NUST)IslamabadPakistan Department of Biotechnology Quaid-i-Azam UniversityIslamabadPakistan Department of Biological Sciences Faculty of Basic&Applied SciencesInternational Islamic University Islamabad(IIUI)IslamabadPakistan Department of Bioengineering King Fahd University of Petroleum and MineralsDhahranSaudi Arabia Department of Physiology College of MedicineKing Saud UniversityRiyadhSaudi Arabia Department of Neurology Neuroscience CenterKing Fahad Specialist HospitalDammamSaudi Arabia Department of Mental Health Neuroscience CenterKing Fahad Specialist HospitalDammamSaudi Arabia Department of Biosciences Commission on Science and Technology for Sustainable Development in the South(COMSATS University)IslamabadPakistan Department of Psychiatry The First Hospital of Hebei Medical UniversityShijiazhuangHebei ProvinceChina Mental Health Institute of Hebei Medical University ShijiazhuangHebei ProvinceChina Department of Neurobiology and Behavior University of CaliforniaIrvineCAUSA Neuroscience Center King Fahad Specialist Hospital DammamDammamSaudi Arabia

The complex morphological,anatomical,physiological,and chemical mechanisms within the aging brain have been the hot topic of research for *** aging process alters the brain structure that affects functions and cognitions,but the worsening of such processes contributes to the pathogenesis of neurodegenerative disorders,such as Alzheimer's *** these observable,mild morphological shifts,significant functional modifications in neurotransmission and neuronal activity critically influence the aging *** these changes is important for maintaining cognitive health,especially given the increasing prevalence of age-related conditions that affect *** review aims to explore the age-induced changes in brain plasticity and molecular processes,differentiating normal aging from the pathogenesis of Alzheimer's disease,thereby providing insights into predicting the risk of dementia,particularly Alzheimer's disease.

关键词： Alzheimer’s disease brain aging cognitive health dementia molecular mechanisms neuronal activity neuroplasticity neurotransmission

Review on nanocomposites fabricated by mechanical alloying

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International Journal of Minerals,Metallurgy and Materials 2019年第9期26卷 1047-1058页

作者： mohammed A. Taha Rasha A. Youness M.f. Zawrah Solid State Physics Department National Research CentreEl Buhouth St.Dokki 12622CairoEgypt Spectroscopy Department National Research CentreEl Buhouth St.Dokki 12622CairoEgypt Refractories Ceramics and Building Material DepartmentNational Research CentreEl Buhouth St.Dokki 12622CairoEgypt

Composites are composed of multiphase materials, where each phase has specific properties that differ from those of the other phases which can effect on the whole properties of composite. Nanocomposites are class of materials that contain at least one phase in the nanometric size range and can be produced by any suitable technique for preparing nanomaterials. Composites are an interesting class of materials that have recently been used in numerous applications, including structural, biomedical, electronics, and environmental applications. In composites, reinforcements might be fibers, particulates, or whiskers. Mechanical alloying(MA) is a promising technique for producing nanocomposite materials that are difficult or impossible to prepare via conventional techniques. In this review, we provide an overview of nanocomposites prepared by the MA process. The mechanism of milling and other milling parameters are overviewed, and insights into sintering categories and parameters are also presented.

关键词： nanocomposites mechanical alloying fabrication sintering

Deflection behavior of a prestressed concrete beam reinforced with carbon fibers at elevated temperatures

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frontiers of Structural and Civil Engineering 2019年第1期13卷 81-91页

作者： mohammed fARUQI mohammed Sheroz KHAN Department of Civil and Architectural Engineering Texas A&M University--KingsvilleTexasUSA

fiber reinforced polymer(fRP) have unique advantages like high strength to weight ratio,excellent corrosion resistance,improving deformability and cost *** advantages have gained wide acceptance in civil engineering *** tendons for prestressing applications are emerging as one of the most promising technologies in the civil engineering ***,the behavior of such members under the influence of elevated temperatures is still *** knowledge and application of this could lead to a cost effective and practical considerations in fire safety ***,this study examines the deflection behavior of the carbon fiber reinforced polymer(CfRP) prestressed concrete beam at elevated *** this article,an analytical model is developed which integrates the temperature dependent changes of effective modulus of fRP in predicting the deflection behavior of CfRP prestressed concrete beams within the range of practical *** model is compared with a finite element mode (fEM) of a simply supported concrete beam prestressed with CfRP subjected to practical elevated *** addition,comparison is also made with an indirect reference to the real behavior of the *** results of the model correlated reasonably with the finite element model and the real ***,a practical application is provided.

关键词： fRP CfRP concrete elevated temperatures deflections prestress

On-line CO,CO_2 emissions evaluation and(benzene, toluene, xylene) determination from experimental burn of tropical biomass

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Journal of Environmental Sciences 2015年第7期27卷 239-244页

作者： mohammed f.Tawfiq Mohamed Kheireddine Aroua Nik Meriam Nik Sulaiman Chemical Engineering Department Faculty of Engineering University of Malaya

Atmospheric pollution and global warming issues are increasingly becoming major environmental concerns. fire is one of the significant sources of pollutant gases released into the atmosphere; and tropical biomass fires, which are of particular interest in this study,contribute greatly to the global budget of CO and CO2. This pioneer research simulates the natural biomass burning strategy in Malaysia using an experimental burning facility. The investigation was conducted on the emissions（CO2, CO, and Benzene, Toluene, Ethylbenzene,Xylenes（BTEX）） from ten tropical biomass species. The selected species represent the major tropical forests that are frequently subjected to dry forest fire incidents. An experimental burning facility equipped with an on-line gas analyzer was employed to determine the burning emissions. The major emission factors were found to vary among the species, and the specific results were as follows. The moisture content of a particular biomass greatly influenced its emission pattern. The smoke analysis results revealed the existence of BTEX,which were sampled from a combustion chamber by enrichment traps aided with a universal gas sampler. The BTEX were determined by organic solvent extraction followed by GC/MS quantification, the results of which suggested that the biomass burning emission factor contributed significant amounts of benzene, toluene, and m,p-xylene. The modified combustion efficiency（MCE） changed in response to changes in the sample moisture ***, this study concluded that the emission of some pollutants mainly depends on the burning phase and sample moisture content of the biomass.

关键词： Emission Biomass Experimental BTEX CO CO2 GG/MS

Highlights in pathogenesis of vitiligo

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World Journal of Clinical Cases 2015年第3期3卷 221-230页

作者： Ghada f mohammed Amal Hussein Gomaa mohammed Saleh Al-Dhubaibi Department of Dermatology and Venereology Faculty of Medicine Suez Canal University Department of Dermatology Faculty of Medicine Qassim University

Vitiligo is a common pigmentary disorder. Many studies across decades and all over the world have attempted to illustrate the pathogenesis behind it; however, the pathogenesis of vitiligo remains elusive. This review article, we present the findings behind the most and updated theories behind this psychologically debilitating and disfiguring disease. The discussion begun with the role of genetic predisposition followed by neural theory first proposed in the 1950 s. Wehighlight the autoimmune hypothesis, followed by the reactive oxygen species model, zinc-α2-glycoprotein deficiency hypothesis, viral theory, intrinsic theory and biochemical, molecular and cellular alterations accounting for loss of functioning melanocytes in vitiligo. Many theories were elaborated to clarify vitiligo pathogenesis. It is a multifactorial disease involving the interplay of several factors. future research is needed to clarify the interaction of these factors for better understanding of vitiligo pathogenesis and subsequent successful treatment.

关键词： Etiopathogenesis Pigmentary disorder Non-segmental vitiligo Segmental vitiligo Vitiligo

Trace-element geochemistry and S–O isotopes in the fluorite-barite mineralization of Merguechoum,Moroccan eastern Meseta:insights into ore genesis to the Pangea rifting

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Acta Geochimica 2023年第3期42卷 435-452页

作者： mohammed Cherai Larbi Rddad fouad Talbi Benjamin f.Walter faculte´des Sciences Laboratoire de GeosciencesGeo-Environnement et Prospection Miniere et HydriqueBP 71760000 OujdaMaroc Earth and Planetary Science Division Physical Science DepartmentKingsborough Community College of the City University of New York(CUNY)2001 Oriental BoulevardBrooklynNY 11235–2398USA Chair of Economic Geology and Geochemistry Karlsruhe Institute of Technology(KIT)Adenauerring 20B76131 KarlsruheGermany Laboratory for Environmental and Raw Material Analyses(LERA) Adenauerring 20B76131 KarlsruheGermany

The Merguechoum fluorite-barite mineralization,located in the Eastern Meseta of Morocco,is hosted in the Late Hercynian *** ore consists of fine crystals of fluorite 1,massive barite 1,euhedral crystals of fluorite 2,and barite 2 with calcite and minor quartz and *** Merguechoum ore deposits have never been *** study was the first contribution that studied the genesis of fluorite and *** ore occurs as dissemination within granite intrusion and also fills the NE-SWtrending meter-sized fractures and *** values of the total Rare Earth Elements and Yttrium(REY)and the ratios of LREY/HREY,Y/Ho,Tb/Ca,and Tb/La indicate that the Merguechoum fluorite precipitated from hydrothermal fluids,likely basinal brines,which interacted with the Hercynian *** REY data indicate that the ore-forming fluids of the early stage have intensely interacted with the Hercynian granite compared to those of the late ore *** gradual decrease in the europium(Eu/Eu^(*)),yttrium(Y/Y^(*)),and cerium(Ce/Ce^(*))anomalies and a low concentration ofΣREY observed in the second ore stage compared to the first ore stage suggest an increase in p H and fO_(2)and by inference a decrease in temperature during the evolution of the hydrothermal *** evolution could be explained by fluid mixing between the ascending basinal hydrothermal fluids and the diluted sulfate-rich meteoric water barite separates from selected samples reveal that the dissolved sulfates(SO_(4)^(2-))were derived from Permian–Triassic sulfates and/or coeval poreseawater *** proposed fluid mixing triggered the precipitation of an early-stage f-Ba assemblage followed by the second-stage f-Ba *** fieldwork,REY inventories,and isotope data point to the ore genesis during the Permian–Triassic extensional tectonic activity concerning the Pangea *** extensional tectonic environment is likely the driving force that mobilized a large amount of the ore

关键词： fluorite-barite veins Geochemistry of REY and trace elements O–S isotopes Late hercynian granite Pangea rifting Merguechoum Eastern Meseta of Moroccan

flow Management Mechanism in Software-Defined Network

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Computers, Materials & Continua 2022年第1期70卷 1437-1459页

作者： Eugene Tan Yung-Wey Chong mohammed f.R.Anbar National Advanced IPv6 Centre Universiti Sains MalaysiaUSMPenangMalaysia

Software-defined networking(SDN)is a paradigm shift in modern ***,centralised controller architecture in SDNimposed flow setup overhead issue as the control plane handles all flows regardless of size and *** frameworks strictly reduce control plane overhead and it does not focus on rule placement of the flows ***,existing frameworks do not focus on managing elephant flows like ***,the proposed mechanism will use the flow statistics gathering method such as random packet sampling to determine elephant flow and microflow via a predefined *** mechanism will ensure that the control plane works at an optimum workload because the controller only manages elephant flows via reactive routing and rule placement *** routing has reduced link bandwidth usage below the pre-defined ***,rule placement has increased average throughput and total transfer to 238%.Meanwhile,the data plane switches will be able to forward microflows via multipath wildcard routing without invoking controller in greater responding time by 85 ms faster in two Transmission Control Protocol(TCP)traffic and achieved 11%and 12%higher total transfer size and throughput ***,the controller’s workload reduced significantly to 48%in two TCP traffic.

关键词： Software-defined network controller flow management

MULTIDIMENSIONAL RELAXATION APPROXIMATIONS fOR HYPERBOLIC SYSTEMS Of CONSERVATION LAWS

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Journal of Computational Mathematics 2007年第4期25卷 440-457页

作者： mohammed Seaid UniversitSt Kaiserslautern fachbereich Mathematik 67663 Kaiserslautern Germany

We construct and implement a non-oscillatory relaxation scheme for multidimensional hyperbolic systems of conservation laws. The method transforms the nonlinear hyperbolic system to a semilinear model with a relaxation source term and linear characteristics which can be solved numerically without using either Riemann solver or linear iterations. To discretize the relaxation system we consider a high-resolution reconstruction in space and a TVD Runge-Kutta time integration. Detailed formulation of the scheme is given for problems in three space dimensions and numerical experiments are implemented in both scalar and system cases to show the effectiveness of the method.

关键词： Multidimensional hyperbolic systems Relaxation methods Non-oscillatory reconstructions Asymptotic-preserving schemes.