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Effect of SrCO_3 addition on the dynamic compressive strength of ZTA

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International Journal of Minerals,Metallurgy and Materials 2016年第4期23卷 481-489页

作者： ali Arab Roslan ahmad Zainal Arifin ahmad School of Mechanical Engineering Universiti Sains Malaysia Engineering Campus Structural Materials Niche Area School of Materials and Mineral Resources Engineering Universiti Sains Malaysia Engineering Campus

Ceramic parts usually experience dynamic load in armor applications. Therefore, studying the dynamic behaviors of ceramics is important. Limited data are available on the dynamic behaviors of ceramics; thus, it is helpful to predict the dynamic strength of ceramics on the basis of their mechanical properties. In this paper, the addition of SrCO3 into zirconia-toughened alumina（ZTA） was demonstrated to improve the fracture toughness of ZTA due to the formation of the SrAl12O19（SA6） phase. The porosity of ZTA was found to be increased by the addition of SrCO3. These newly formed pores served as the nucleation sites of cracks under dynamic load; these cracks eventually coalesced to form damaged zones in the samples. Although the KIC values of the samples were improved, the dynamic strength was not enhanced because of the increase in porosity; in fact, the dynamic strength of ZTA ceramics decreased with the addition of SrCO3.

关键词： ceramics strontium carbonate dynamic properties fracture toughness compressive strength

Viscous effects on plasmoid formation from nonlinear resistive tearing growth in a Harris sheet

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Plasma Science and Technology 2022年第1期24卷 18-29页

作者： Nisar ahmad Ping ZHU ahmad ali Shiyong ZENG CAS Key Laboratory of Geospace Environment and Department of Engineering and Applied Physics University of Science and Technology of ChinaHefei 230026People's Republic of China International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People's Republic of China Department of Engineering Physics University of Wisconsin-MadisonMadisonWisconsin 53706United States of America Pakistan Tokamak Plasma Research Institute Islamabad 44000Pakistan Department of Plasma Physics and Fusion Engineering University of Science and Technology of ChinaHefei 230026People’s Republic of China

In this work,the evolution of a highly unstable m=1 resistive tearing mode,leading to plasmoid formation in a Harris sheet,is studied in the framework of full MHD model using the Non-Ideal Magnetohydrodynamics with Rotation,Open Discussion *** the initial nonlinear growth of the primary m=1 island,the X-point develops into a secondary elongated current sheet that eventually breaks into *** distinctive viscous regimes are found for the plasmoid formation and *** the low viscosity regime(i.e.P_(r)■1),the plasmoid width increases sharply with viscosity,whereas in the viscosity dominant regime(i.e.P_(r)■1),the plasmoid size gradually decreases with *** a finding quantifies the role of viscosity in modulating the plasmoid formation process through its effects on the plasma flow and the reconnection itself.

关键词： viscosity reconnection plasmoids Prandtl number

Color-flavor dependence of the Nambu-Jona-Lasinio model and QCD phase diagram

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Chinese Physics C 2022年第8期46卷 128-140页

作者： Aftab ahmad ali Murad Institute of Physics Gomal University29220D.I.KhanKhyber PakhtunkhawPakistan

We study the dynamical chiral symmetry breaking/restoration for various numbers of light quarks flavors N_(f) and colors N_(c) using the Nambu-Jona-Lasinio(NJL) model of quarks in the Schwinger-Dyson equation framework,dressed with a color-flavor dependence of effective *** fixed N_(f)=2 and varying N_(c),we observe that the dynamical chiral symmetry is broken when N_(c) exceeds its critical value N_(c)^(c)≈*** a fixed N_(c)=3 and varying N_(f),we observe that the dynamical chiral symmetry is restored when Nf reaches its critical value N_r^(c)≈*** interplay is observed between N_(c) and N_(f),i.e.,larger values of N_(c) tend to strengthen the dynamical generated quark mass and quark-antiquark condensate,while higher values of N_(f) suppress both *** further sketch the quantum chromodynamics(QCD) phase diagram at a finite temperature T and quark chemical potential μ for various N_(c) and N_(f).At finite T and μ,we observe that the critical number of colors N_(c)^(c) is enhanced,whereas the critical number of flavors N_(f)^(c) is suppressed as T and μ ***,the critical temperature T_(c),μ_(c),and co-ordinates of the critical endpoint(T_(c)^(E),μ_(c)^(E)) in the QCD phase diagram are enhanced as N_(c) increases and suppressed when N_(f) *** findings agree with the lattice QCD and Schwinger-Dyson equations predictions.

关键词： chiral symmetry breaking Schwinger-Dyson equation finite temperature and density QCD phase diagram

Damage detection of 3D structures using nearest neighbor search method

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Earthquake Engineering and Engineering Vibration 2021年第3期20卷 705-725页

作者： ali Abasi Vahid Harsij ahmad Soraghi Department of Civil and Environmental Engineering Western UniversityLondonONCanada Department of Civil Engineering Amirkabir University of Technology(Tehran Polytechnic)TehranIran Department of Civil Engineering University of AkronASEC 210Sumner StAkronOH 44325USA

An innovative damage identification method using the nearest neighbor search method to assess 3D structures is *** frequency response function was employed as the input parameters to detect the severity and place of damage in 3D spaces since it includes the most dynamic characteristics of the ***-dimensional principal component analysis was utilized to reduce the size of the frequency response function *** nearest neighbor search method was employed to detect the severity and location of damage in different damage *** accuracy of the approach was verified using measured data from an experimental test;moreover,two asymmetric 3D numerical examples were considered as the numerical *** superiority of the method was demonstrated through comparison with the results of damage identification by using artificial neural *** levels of white Gaussian noise were used for polluting the frequency response function data to investigate the robustness of the methods against noise-polluted *** results indicate that both methods can efficiently detect the damage properties including its severity and location with high accuracy in the absence of noise,but the nearest neighbor search method is more robust against noisy data than the artificial neural network.

关键词： damage identification damage index frequency response function two-dimensional principal component analysis nearest neighbor search artificial neural network white Gaussian noise

Polynomials of Degree-Based Indices for Three-Dimensional Mesh Network

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Computers, Materials & Continua 2020年第11期65卷 1271-1282页

作者： ali N.A.Koam ali ahmad Department of Mathematics College of ScienceJazan UniversityJazan45142Saudi Arabia College of Computer Science and Information Technology Jazan UniversityJazan45142Saudi Arabia

In order to study the behavior and interconnection of network devices,graphs structures are used to formulate the properties in terms of mathematical *** network(meshnet)is a LAN topology in which devices are connected either directly or through some intermediate *** terminating and intermediate devices are considered as vertices of graph whereas wired or wireless connections among these devices are shown as edges of *** indices are used to reflect structural property of graphs in form of one real *** structural invariant has revolutionized the field of chemistry to identify molecular descriptors of chemical *** indices are extensively used for establishing relationships between the structure of nanotubes and their physico-chemical *** this paper a representation of sodium chloride(NaCl)is studied,because structure of NaCl is same as the Cartesian product of three paths of length exactly like a mesh *** this way the general formula obtained in this paper can be used in chemistry as well as for any degree-based topological polynomials of three-dimensional mesh networks.

关键词： Topological polynomials degree-based index three-dimensional mesh network chemical compounds

Implication of Surface Fractal Analysis to Evaluate the Relative Sensitivity of Topography to Active Tectonics,Zagros Mountains, Iran

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Journal of Mountain Science 2015年第1期12卷 177-185页

作者： ali Faghih ahmad Nourbakhsh Department of Earth Sciences College of Sciences Shiraz University

Fractal geometry is increasingly becoming a useful tool for modeling and quantifying the complex patterns of natural phenomena. The Earth's topography is one of these phenomena that have fractal characteristics. This paper investigates the relative sensitivity of topography to active tectonics using ASTER Global Digital Elevation Model. The covering divider method was used for direct extraction of surface fractal dimension(D surf) to estimate the roughness-surface of topography with aid of geographic information system(GIS)techniques. This evaluation let us highlight the role of the geomorphic and tectonic processes on the spatial variability of fractal properties of natural *** zones can be delineated using fractal dimension mapping in which variability of surface fractal dimension reflects the roughness of the landform surface and is a measure of topography texture. Obtained results showed this method can be a quick and easy way to assess the distribution of land surface deformation in different tectonic settings. The loose alluvial deposits and irregularities derived by tectonic activity have high fractal dimensions whereas the competent formations and higher wavelength folded surfaces have lower fractal *** to the obtained results, the Kazerun Fault Zone has a crucial role in the separation of the Zagros Mountain Ranges into the different lithological,geomorphological and structural zones.

关键词： Surface fractal analysis Topography Active tectonics Kazerun Fault Zone Zagros Iran

A Measurement Study of the Ethereum Underlying P2P Network

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Computers, Materials & Continua 2024年第1期78卷 515-532页

作者： Mohammad ZMasoud Yousef Jaradat ahmad Manasrah Mohammad alia Khaled Suwais Sally Almanasra Electrical Engineering Department Al-Zaytoonah University of JordanAmman11733Jordan Mechanical Engineering Department Al-Zaytoonah University of JordanAmman11733Jordan Computer Science Department Al-Zaytoonah University of JordanAmman11733Jordan Faculty of Computer Studies Arab Open UniversityRiyadh11681Saudi Arabia

This work carried out a measurement study of the Ethereum Peer-to-Peer(P2P)network to gain a better understanding of the underlying *** was applied because it pioneered distributed applications,smart contracts,and ***,its application layer language“Solidity”is widely used in smart contracts across different public and private *** this end,we wrote a new Ethereum client based on Geth to collect Ethereum node ***,various web scrapers have been written to collect nodes’historical data fromthe Internet Archive and the Wayback Machine *** collected data has been compared with two other services that harvest the number of *** has collectedmore than 30% more than the other *** data trained a neural network model regarding time series to predict the number of online nodes in the *** findings show that there are less than 20% of the same nodes daily,indicating thatmost nodes in the network change *** poses a question of the stability of the ***,historical data shows that the top ten countries with Ethereum clients have not changed since *** popular operating system of the underlying nodes has shifted from Windows to Linux over time,increasing node *** results have also shown that the number of Middle East and North Africa(MENA)Ethereum nodes is neglected compared with nodes recorded from other *** opens the door for developing new mechanisms to encourage users from these regions to contribute to this ***,the model has been trained and demonstrated an accuracy of 92% in predicting the future number of nodes in the Ethereum network.

关键词： Ethereum measurement ethereum client neural network time series forecasting web-scarping wayback machine blockchain

Improvement of microstructure and corrosion properties of friction stir welded AA5754 by adding Zn interlayer

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International Journal of Minerals,Metallurgy and Materials 2018年第8期25卷 967-973页

作者： ali Shamsipur Amir Anvari ahmad Keyvani Department of Mining and Metallurgical Engineering Amirkabir University of Technology School of Metallurgy and Materials Engineering Faculty of Technology and EngineeringShahrekord University

This study investigated the effect of Zn foil layers on the microstructure and corrosion characteristics of friction stir welded aluminum alloy *** of various joints were prepared by applying different rotational and welding speeds,and their microstructures were evaluated via a metallographic technique and scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy elemental *** anticorrosion behavior of joints in the absence and presence of a Zn interlayer was studied by cyclic potentiodynamic polarization test in 3.5 wt% Na Cl aqueous solution,and sound welds were obtained in the presence of the Zn interlayer *** results revealed that the joint made at a rotational speed of 800 r/min and traveling speed of 15 mm/min achieved a chemical composition identical to that of aluminum alloy 7 xxx series,and as such,it showed the best resistance to corrosion.

关键词： friction stir welding AA5754 aluminum alloy zinc interlayer microstructure corrosion resistance

Catalytic evaluation of promoted CeO_2-ZrO_2 by transition, alkali, and alkaline-earth metal oxides for diesel soot oxidation

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Journal of Environmental Sciences 2013年第12期25卷 2498-2506页

作者： ali alinezhadchamazketi Abas ali Khodadadi Yadollah Mortazavi ahmad Nemati Catalysis and Nanostructured Materials Laboratory College of EngineeringSchool of Chemical EngineeringUniversity of Tehran Oil and Gas Processing Center of Excellence College of EngineeringUniversity of Tehran

Series of mixed metal oxides were synthesized by gel-combustion method and their catalytic activities for soot oxidation were investigated. The catalysts were M-Ce-Zr （M = Mn, Cu, Fe, K, Ba, Sr）, and χK-20Mn-Ce-Zr （χ= 0, 5, 10, 20）, they were characterized by XRD, SEM, TPR and BET surface area techniques. The results of soot temperature programmed oxidation （TPO） in an O2 oxidizing atmosphere indicate that K-Ce-Zr has the highest catalytic activity for soot oxidation under loose contact condition, due to enhancement of the soot and catalyst contacts. On the other hand, under a tight contact condition, Mn-Ce-Zr and Cu-Ce-Zr nano-composites have high activities for soot oxidation and lower the soot TPO peak temperatures by about 280 and 270℃, respectively, as compared to non-catalytic soot oxidation. Furthermore, the addition of up to 10 wt.% potassium oxides into Mn-Ce-Zr increases its catalytic activity and further reduces the soot TPO peak temperature by about 40℃ under loose contact condition.

关键词： soot oxidation diesel ceria-zirconia metal oxide