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

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

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Experimental and numerical settlement analysis of railway track over geogrid reinforced ballast

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Railway Sciences 2024年第3期3卷 311-331页

作者： mohammed Y.fattah Mahmood R.Mahmood mohammed f.aswad Department of Civil Engineering UOTBaghdadIraq

Purpose-The main objective of the present research is to investigate the benefits of using geogrid reinforcement in minimizing the rate of deterioration of ballasted rail track geometry resting on soft clay and to explore the effect of load amplitude,load frequency,presence of geogrid layer in ballast layer and ballast layer thickness on the behavior of track *** variables are studied both experimentally and *** paper examines the effect of geogrid reinforced ballast laying on a layer of clayey soil as a subgrade layer,where a half full scale railway tests are conducted as well as a theoretical analysis is ***/methodologylapproach-The experimental tests work consists of laboratory model tests to investigate the reduction in the compressibility and stress distribution induced in soft clay under a ballast railway reinforced by geogrid reinforcement subjected to dynamic *** model based on an approximate half scale for general rail track engineering practice is adopted in this study which is used in Iraqi *** investigated parameters are load amplitude,load frequency and presence of geogrid reinforcement layer.A half fuli-scale railway was constructed for carrying out the tests,which consists of two rails 800 mm in iength with three w00den sleepers(900 mm×90 mm×90 mm).The ballast was overlying 500 mm thick clay *** tests were carried out with and without geogrid reinforcement,the tests were carried out in a well tied steel box of 1.5 m length X 1 m width X 1 m height.A series of laboratory tests were conducted to investigate the response of the ballast and the clay layers where the ballast was reinforced by a *** in ballast and clay,was measured in reinforced and unreinforced ballast *** addition to the laboratory tests,the application of numerical analysis was made by using the finite element program PLAXIS 3D ***-It was concluded that the settlement increased with increasing t

关键词： Track ettlement Ballast finiteelements

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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

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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

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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

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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

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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

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Entropy and Entanglement in Master Equation of Effective Hamiltonian for Jaynes-Cummings Model

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Communications in Theoretical Physics 2009年第4期51卷 723-728页

作者： H.A.Hessian f.A.mohammed A.-B.A.Mohamed faculty of Science Assiut University

In this paper, we analytically solve the master equation for Jaynes-Cummings model in the dispersive regime including phase damping and the field is assumed to be initially in a superposition of coherent states. Using an established entanglement measure based on the negativity of the eigenvalues of the partially transposed density matrix we find a very strong sensitivity of the maximally generated entanglement to the amount of phase damping. Qualitatively this behavior is also reflected in alternative entanglement measures, but the quantitative agreement between different measures depends on the chosen noise model The phase decoherence for this model results in monotonic increase in the total entropy while the atomic sub-entropy keeps its periodic behaviour without any effect.

关键词： entanglement phase damping master equation superposition state

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Effective Controller Placement in Software-Defined Internet-of-Things Leveraging Deep Q-Learning (DQL)

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Computers, Materials & Continua 2024年第12期81卷 4015-4032页

作者： Jehad Ali mohammed J.f.Alenazi Department of AI Convergence Network Ajou UniversitySuwon16499Republic of Korea Department of Computer Engineering College of Computer and Information SciencesKing Saud UniversityRiyadh11362Saudi Arabia

The controller is a main component in the Software-Defined Networking(SDN)framework,which plays a significant role in enabling programmability and orchestration for 5G and next-generation *** SDN,frequent communication occurs between network switches and the controller,which manages and directs traffic *** the controller is not strategically placed within the network,this communication can experience increased delays,negatively affecting network ***,an improperly placed controller can lead to higher end-to-end(E2E)delay,as switches must traverse more hops or encounter greater propagation delays when communicating with the *** paper introduces a novel approach using Deep Q-Learning(DQL)to dynamically place controllers in Software-Defined Internet of Things(SD-IoT)environments,with the goal of minimizing E2E delay between switches and controllers.E2E delay,a crucial metric for network performance,is influenced by two key factors:hop count,which measures the number of network nodes data must traverse,and propagation delay,which accounts for the physical distance between *** approach models the controller placement problem as a Markov Decision Process(MDP).In this model,the network configuration at any given time is represented as a“state,”while“actions”correspond to potential decisions regarding the placement of controllers or the reassignment of switches to *** a Deep Q-Network(DQN)to approximate the Q-function,the system learns the optimal controller placement by maximizing the cumulative reward,which is defined as the negative of the E2E ***,the lower the delay,the higher the reward the system receives,enabling it to continuously improve its controller placement *** experimental results show that our DQL-based method significantly reduces E2E delay when compared to traditional benchmark placement *** dynamically learning from the network’s real-time conditions,the prop

关键词： Software-defined networking deep Q-learning controller placement quality of service

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Threshold-Based Software-Defined Networking(SDN)Solution for Healthcare Systems against Intrusion Attacks

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Computer Modeling in Engineering & Sciences 2024年第2期138卷 1469-1483页

作者： Laila M.Halman mohammed J.f.Alenazi Department of Computer Engineering College of Computer ScienceKing Saud UniversityRiyadh11451Saudi Arabia

The healthcare sector holds valuable and sensitive *** amount of this data and the need to handle,exchange,and protect it,has been increasing at a fast *** to their nature,software-defined networks(SDNs)are widely used in healthcare systems,as they ensure effective resource utilization,safety,great network management,and *** this sector,due to the value of thedata,SDNs faceamajor challengeposed byawide range of attacks,such as distributed denial of service(DDoS)and probe *** attacks reduce network performance,causing the degradation of different key performance indicators(KPIs)or,in the worst cases,a network failure which can threaten human *** can be significant,especially with the current expansion of portable healthcare that supports mobile and wireless devices for what is called mobile health,or *** this study,we examine the effectiveness of using SDNs for defense against DDoS,as well as their effects on different network KPIs under various *** propose a threshold-based DDoS classifier(TBDC)technique to classify DDoS attacks in healthcare SDNs,aiming to block traffic considered a hazard in the form of a DDoS *** then evaluate the accuracy and performance of the proposed TBDC *** technique shows outstanding performance,increasing the mean throughput by 190.3%,reducing the mean delay by 95%,and reducing packet loss by 99.7%relative to normal,with DDoS attack traffic.

关键词： Network resilience network management attack prediction software defined networking(SDN) distributed denial of service(DDoS) healthcare

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