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Nuclear Science and Techniques 2004年第6期15卷 368-374页

作者： k. k.MURA N.k. ahmed A.H. EL-k.MEL A.M.M. YOUSEF Low Level Radioactivity Laboratory Kanazawa University Wake Tatsunokuchi Ishikawa 923-1224 JapanPhysics Department Faculty of Science South Valley University Kena EgyptPhysics Department Faculty of Science Assiut University Assiut EgyptPhysics Department Faculty of Science South Valley University Kena Egypt

The activation of gold by environmental neutrons through the reaction 197Au (n,γ) 198Au was used to study the effect of concrete buildings on the neutron flux, and to estimate the thermal neutron flux inside and outside these buildings. The results showed that three ceilings of thick.ess 34 g/cm2 decrease the fast neutrons to 26% from its original value. However, the same reinforced concrete decreases the slow neturon flux to only 62% of its original value. The thermal neutron flux at 283 m from the center of Training Reactor of k.nk. University, was twice higher than the environmental neutron back.round.

关键词：金活性混凝土环境中子宇宙射线

Solitary k.netic Alfven waves in dense plasmas with relativistic degenerate electrons and positrons

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Plasma Science and Technology 2019年第4期21卷 85-93页

作者： Monzurul k.ahmed Om P SAH Department of Physics Biijhora MahavidyalayaBongaigaon-783380AssamIndia

Propagation of solitary k.netic Alfven waves(k.Ws)is investigated in small but finite/3(particle-to-magnetic pressure ratio)collisionless dense plasma whose constituents are non degenerate wann ions,and relativistic degenerate electrons and *** the use of reductive perturbation technique,k.rtweg-de Vries equation is derived to obtain small amplitude localized wave solution of *** effects of plasma 0,positron concentration,electron relativistic degeneracy parameter,ion thermal temperature and obliqueness parameter on solitary k.Ws are *** results of this theoretical investigation are aimed at elucidating characteristics of k.netic Alfven solitary waves in relativistic degenerate e-p-i plasmas found in dense astrophysical objects specifically neutron stars and white dwarfs.

关键词： solitary k.netic Alfven waves dense plasmas electron-positron-ion plasma,relativistic degenerate plasma reductive perturbation technique

Solitary k.netic Alfvén waves in a dense electron–positron–ion plasma with degenerate electrons and positrons

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Plasma Science and Technology 2017年第12期19卷 42-49页

作者： Monzurul k.ahmed Om P SAH Depatment of Physics Birjhora MahavidyalayaBongaigaon-783380AssamIndia

Through the use of a reductive perturbation technique, solitary k.netic Alfvén waves（k.Ws） are investigated in a low but finite b（particle-to-magnetic pressure ratio） dense electron–positron–ion plasma where electrons and positrons are degenerate. The degenerate plasma model considered here permits the existence of sub-Alfvénic compressive solitary k.Ws. The influence of r（equilibrium positron-to-ion density ratio）, sF（electron-to-positron Fermi temperature ratio）, b and obliqueness parameter lzon various characteristics of solitary k.Ws are examined through numerical plots. We have shown that there exists a critical value of lzat which a soliton width attains its maximum value which decreases with an increase in r and *** is also found that solitons with a higher energy propagate more obliquely in the direction of an ambient magnetic field. The results of the present investigation may be useful for understanding low frequency nonlinear electromagnetic wave propagation in magnetized electron–positron–ion plasmas in dense stars. Specifically, the relevance of our investigation to a pulsar magnetosphere is emphasized.

关键词： k.netic Alfvén waves solitons electron–positron–ion plasma degenerate plasma Thomas–Fermi approximation

Connected Components-based Colour Image Representations of Vibrations for a Two-stage Fault Diagnosis of Roller Bearings Using Convolutional Neural Network.

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Chinese Journal of Mechanical Engineering 2021年第3期34卷 73-93页

作者： Hosameldin O.A.ahmed Asok. k.Nandi Department of Electronic and Electrical Engineering Brunel University LondonUxbridge UB83PHUK School of Mechanical Engineering Xi’an Jiaotong UniversityXi’anChina

Roller bearing failure is one of the most common faults in rotating *** techniques for bearing fault diagnosis based on faults feature extraction have been *** feature extraction from fault signals requires expert prior information and human ***,deep learning algorithms have been applied extensively in the condition monitoring of rotating machines to learn features automatically from the input *** its robust performance in image recognition,the convolutional neural network.CNN)architecture has been widely used to learn automatically discriminative features from vibration images and classify health *** paper proposes and evaluates a two-stage method RGBVI-CNN for roller bearings fault *** first stage in the proposed method is to generate the RGB vibration images(RGBVIs)from the input vibration *** begin this process,first,the 1-D vibration signals were converted to 2-D grayscale vibration *** the conversion was completed,the regions of interest(ROI)were found in the converted 2-D grayscale vibration ***,to produce vibration images with more discriminative characteristics,an algorithm was applied to the 2-D grayscale vibration images to produce connected components-based RGB vibration images(RGBVIs)with sets of colours and texture *** the second stage,with these RGBVIs a CNN-based architecture was employed to learn automatically features from the RGBVIs and to classify bearing health *** cases of fault classification of rolling element bearings are used to validate the proposed *** results of this investigation demonstrate that RGBVI-CNN can generate advantageous health condition features from bearing vibration signals and classify the health conditions under different work.ng loads with high ***,several classification models trained using RGBVI-CNN offered high performance in the testing results of the overall classification accura

关键词： Bearing fault diagnosis Image representation of vibrations Deep learning Convolutional neural network.

Finite element modeling assumptions impact on seismic response demands of MRF-buildings

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Earthquak. Engineering and Engineering Vibration 2018年第4期17卷 821-834页

作者： Shehata E Abdel Raheem ahmed k.Abdel Zaher ahmed MA Taha Civil Engineering Department Engineering College Taibah University Civil Engineering Department Faculty of Engineering Assiut University

Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame ＂RC-MRF＂ buildings. The seismic response of such buildings is greatly dependent on the computational tools used and the inherent assumptions in the modelling process. Thus, it is essential to investigate the sensitivity of the response demands to the corresponding modelling assumption. Many parameters and assumptions are justified to generate effective structural finite element（FE） models of buildings to simulate lateral behaviour and evaluate seismic design demands. As such, the present study focuses on the development of reliable FE models with various levels of refinement. The effects of the FE modelling assumptions on the seismic response demands on the design of buildings are investigated. the predictive ability of a FE model is tied to the accuracy of numerical analysis; a numerical analysis is performed for a series of symmetric buildings in active seismic zones. The results of the seismic response demands are presented in a comparative format to confirm drift and strength limits requirements. A proposed model is formulated based on a simplified modeling approach, where the most refined model is used to calibrate the simplified model.

关键词： RC-MRF buildings design codes provisions seismic design finite element modeling modeling assumptions response demands

Estimation of Pore Charge on Zirconia Membrane Prepared by Sol-gel Route Using Zeta Potential Measurement

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Journal of Materials Science & Technology 1998年第5期14卷 425-428页

作者： Seshadri, k.S. ahmed, Jallel k.savamoorthy, R. Varatharajan, k. Srinivasan, M.P. k.ishnasamy, V. Centralised Waste Management Facility Kalpakkam Tkmil Nadu -603 102 India Material Science Laboratory IGCAR Kalpakkam India Water and Steam Chemistry Laboratory IGCAR Kalpakkam India Dept. of Chemical Engineering Anna University Chennai India

Zirconia membrane was prepared in the sol-gel process by filtering viscous colloidal zirconia sol through microporous alumina support and gelling followed by sintering at 743 k. The scanning electron micrograph shows that mean pore size is 543 nm and pore density is 1.47 multiplied by 10**7/cm**2. The filtration characteristics during membrane layer formation show that the membrane layer formation starts after 40 min. The membrane layer thick.ess and the porosity of the membrane were determined gravimetrically by finding out the amount of water present in the pores. The membrane layer thick.ess was found to be 3 micron and the porosity was found out to be 0.38. The pore charge density was estimated from the particle charge density, pore density, pore diameter and the thick.ess of the membrane layer. (Edited author abstract) 5 Refs.

关键词： Zirconia

An energetic nano-fiber composite based on polystyrene and 1,3,5-trinitro-1,3,5-triazinane fabricated via electrospinning technique

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Defence Technology（防务技术） 2023年第9期27卷 1-8页

作者： Mahmoud Abdelhafiz ahmed k.Hussein Waleed F.k.alil ahmed Elbeih Military TechnicalCollege(MTC) KobryElkobbahCairoEgypt Safety FuelCycleDepartment NRSRCEgyptianAtomicEnergyAuthority(EAEA)CairoEgypt

Electrospinning is a simple technique used to fabricate polymeric nano-fibrous *** nano-fibers have found a wide range of valuable applications in the biomedical ***,it has not been utilized with solid high explosives ***,the electrospinning technique has been used to fabricate polystyrene(PS)/1,3,5-trinitro-1,3,5-triazinane(RDX)composite *** governed electrospinning parameters,voltage,distance from the collector,flow rate,mandrel rotating speed,time,and solution concentration,that greatly affect the morphology of the obtained nanofibers were *** fabricated PS/RDX nano-fibers were characterized using scanning electron microscopy(SEM),X-ray diffractometer(XRD),and Fourier Transform Infrared(FTIR)*** impact and friction sensitivities of PS/RDX were also *** thermal behavior of the prepared composite and the pure materials were studied by the thermal gravimetric analysis technique(TGA).SEM results proved the fabrication of PS/RDX fibers in the nano-size via *** spectroscopy confirmed the existence of the characteristic functional groups of both PS and RDX in the composite *** sharp peak. showed the conversion of amorphous PS into crystalline shape via electrospinning and also confirmed the formation of PS/RDX *** PS fibers absorbed the heat and increased the onset decomposition of the pure RDX from 181.5 to 200.7℃in the case of PS/RDX ***,PS/RDX nano-fibers showed the relatively low impact and friction sensitivities of 100 J and 360 N *** results could introduce PS/RDX nanofibrous composite in the field of explosives detection with high levels of safety.

关键词： Electrospinning Nano-fibers 1,3,5-Trinitro-1,3,5-triazinane(RDX) Polystyrene(PS) Sensitivity

Preparation and Properties of PBXs Based on FOX-7 in Controlled Fragmentation Warhead Application

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含能材料 2018年第10期26卷 843-849页

作者： k.rim k.Elshark.wy Lin Guo ahmed M Enew School of Chemistry and Environment Beijing University of Aeronautics and Astronautics Chemical Department Faculty of EngineeringCairo University

Polymer bonded explosive(PBX)formulations were successfully prepared in the laboratory scale containing 1,1-diamino-2,2-dinitroethene(FOX-7)and hexogen(RDX)as brisant high explosives and different binder types of polyurethane(PU)based on glycidyl azide polymer(GAP) and hydroxyl-terminated polybutadiene(HTPB) as an energetic and inert polymeric binder *** technique was used for the preparation of different PBX formulations based on FOX-7/RDX and PU(GAP/HTPB)with 14% *** sensitivity to different initial impulses and performance characteristics of the explosive and lethal zone of the tested controlled fragmentation warhead by the fragmentation warhead assessment test(arena test)were studied,in which the arena test was carried out with a controlled fragmentation warhead made from Ck.5 steel,with dimensions(100 mm length,30 mm outer diameter and 3 mm thick.ess).Results show that PBXGF4 has lower sensitivity to impact and heat than those of PBXGR4 by 188.4% and 3.2% *** friction sensitivity is the same as that of *** has better performance,in which detonation velocity increases by 2.1% and brisance increases by 0.5% when compared with those of *** was concluded that PBXGF4 which based on FOX-7 bonded with PU/GAP matrix has good characteristics as PBX,specially in the sensitivity to impact and can be applied for replacing PBXs based on RDX in the advanced PBXs for low sensitive fragmentation warheads.

关键词： polymer bonded explosive(PBX) controlled fragmentation warhead 1,1-diamino-2,2-dinitroethene(FOX-7) hexo-gen(RDX) preparation sensitivity performance characterization arena test

Relative Explosive Strength of Some Explosive Mixtures Containing Urea and/or Peroxides

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火炸药学报 2016年第5期39卷 22-27,34页

作者： ahmed k.HUSSEIN Svatopluk.ZEMAN Muhamed SUCESk. Marcela JUNGOVA Institute of Energetic Materials Faculty of Chemical Technology University of Pardubice Czech Republic Brodarsk. Institute-Marine Research and Special Technologies ZagrebCroatia

Several mixtures,based on urea derivatives and some inorganic oxidants,including also alumina,were studied by means of ballistic mortar techniques with TNT as the reference *** detonation pressure(P),detonation velocity(D),detonation energy(Q),and volume of gaseous product at standard temperature and pressure(STP),V,were calculated using EXPLO5V6.3 thermochemical *** performance of the mixtures studied was discussed in relation to their thermal reactivity,determined by means of differential thermal analysis(DTA).It is shown that the presence of hydrogen peroxide in the form of its complex with urea(*** UHP)has a positive influence on the explosive strength of the corresponding mixtures which is link.d to the hydroxy-radical formation in the mixtures during their initiation *** radicals might initiate(at least partially)powdered aluminum into oxidation in the CJ plane of the detonation *** containing UHP and magnesium are dangerous because of potential auto-ignition.

关键词： ballistic mortar TNT DTA peroxides perchlorates nitrates urea

Crystal lattice free volume and thermal decomposition of nitramines

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Defence Technology（防务技术） 2019年第1期15卷 51-57页

作者： Svatopluk.Zeman Ning Liu ahmed k.Hussein Institute of Energetic Materials Faculty of Chemical TechnologyUniversity of Pardubice Xi’an Modern Chemistry Research Institute

The linear, directly proportional, equations between the Arrhenius parameters(E_α, and log A) of the thermal decomposition and the crystal lattice free space per molecule, △V, of 22 nitramines are described. It is shown that, because of a significant limitation by the molecular structural characteristics of such compounds, they are divided into a number of partial relationships. These partial relationships divide the nitramines into a group of substances relating to dimethyl nitramine and a sub-group related to e-HNIW. These directly proportional equations mean that an increase in the △Vvalues is related to an increase in the thermal stability of the corresponding nitramines. A comparison with similar published dependencies for the impact and friction sensitivities, on the one hand, and with the relationship between the E_a values and the sum of the negative and positive extremes of molecular surface electrostatic potentials, on the other, confirms the well-k.own fact that intermolecular interaction in the nitramines studied plays a decisive role in the thermal reactivity of such compounds. The crystal lattice free space manifests itself here perhaps only in the solid state thermal decomposition of RDX, HMX and DINGU. This study again confirms a level of disorder in the distribution of the forces in the crystal lattice of the"common" quality of e-HNIW,compared with its "reduced sensitivity(RS)" or pure analogues.

关键词： Crystal lattice Thermal decomposition Initiation reactivity Nitramines