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Multi-segmented nanowires for vortex magnetic domain wall racetrack memory

Chinese Physics B 2023年第12期32卷 582-588页

作者： M al Bahri M al Hinaai T al Harthy Department of Basic Sciences A'Sharqiyah UniversityPost Box 42PC 400IbraOman

A vortex domain wall's(VW) magnetic racetrack memory's high performance depends on VW structural stability,high speed, low power consumption and high storage density. In this study, these critical parameters were investigated in magnetic multi-segmented nanowires using micromagnetic simulation. Thus, an offset magnetic nanowire with a junction at the center was proposed for this purpose. This junction was implemented by shifting one portion of the magnetic nanowire horizontally in the x-direction(l) and vertically(d) in the y-direction. The VW structure became stable by manipulating magnetic properties, such as magnetic saturation(M_(4)) and magnetic anisotropy energy(K_(u)). In this case, increasing the values of M_(4) ≥ 800 kA/m keeps the VW structure stable during its dynamics and pinning and depinning in offset nanowires,which contributes to maintenance of the storage memory's lifetime for a longer period. It was also found that the VW moved with a speed of 500 m/s, which is desirable for VW racetrack memory devices. Moreover, it was revealed that the VW velocity could be controlled by adjusting the offset area dimensions(l and d), which helps to drive the VW by using low current densities and reducing the thermal-magnetic spin fluctuations. Further, the depinning current density of the VW(J_(d)) over the offset area increases as d increases and l decreases. In addition, magnetic properties, such as the M_(4) and K_(u),can affect the depinning process of the VW through the offset area. For high storage density, magnetic nanowires(multisegmented) with four junctions were designed. In total, six states were found with high VW stability, which means three bits per cell. Herein, we observed that the depinning current density(J_(d)) for moving the VW from one state to another was highly influenced by the offset area geometry(l and d) and the material's magnetic properties, such as the M_(4) and K_(u).

关键词： micromagnetic simulation vortex domain wall racetrack memory multi-segmented magnetic nanowire spin transfer torque

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Road scene analysis for determination of road traffic density

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Frontiers of Computer Science 2014年第4期8卷 619-628页

作者： Omar al-KADI Osama al-KADI Rizik al-SAYYED Ja'far alQATAWNA King Abdullah lI School for Information Technology University of Jordan Amman 11942 Jordan College of Engineering and Computer Science Australian National University Canberra ACT 0200 Australia

Road traffic density has always been a concern in large cities around the world, and many approaches were developed to assist in solving congestions related to slow traffic flow. This work proposes a congestion rate estimation approach that relies on real-time video scenes of road traffic, and was implemented and evaluated on eight different hotspots covering 33 different urban roads. The approach relies on road scene morphology for estimation of vehicles average speed along with measuring the overall video scenes randomness acting as a frame texture analysis indicator. Experimental results shows the feasibility of the proposed approach in reliably estimating traffic density and in providing an early warning to drivers on road conditions, thereby mitigating the negative effect of slow traffic flow on their daily lives.

关键词： road congestion image texture local binary pattern scene morphology

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Resistance to acid degradation,sorptivity,and setting time of geopolymer mortars

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Frontiers of Structural and Civil Engineering 2022年第6期16卷 781-791页

作者： Osama A MOHAMED Rania al-KHATTAB Waddah al-HAWAT College of Engineering Abu Dhabi UniversityAbu DhabiUnited Arab Emirates

Experimental evaluations were conducted to determine the water sorptivity,setting time,and resistance to a highly acidic environment,of mortar with alkali-activated ground granulated blast furnace slag(GBS)binder and also of combinations of fly ash and GBS *** were activated using mixtures of NaOH and Na_(2)SiO_(3)*** molarity of NaOH in the mixtures ranged from 10 mol·L^(−1)to 16 mol·L^(−1),and the Na_(2)SiO_(3)/NaOH ratio was varied from 1.5 to *** samples were produced using three binder combinations:1)GBS as the only binder;2)blended binder with a slag-to-fly ash ratio of 3:1;and 3)mixed binder with 1:1 ratio of slag to fly *** samples were mixed and cured at(22±2)°C till the day of the *** impact of activator solution alkalinity,activator ratio Na_(2)SiO_(3)/NaOH,GBS content on the rate of water absorption were *** 7,28,and 90 d of immersion in a 10%sulfuric acid solution,the resistance of a geopolymer matrix to degradation was assessed by measuring the change in sample *** influence of solution alkalinity and relative fly ash content on setting times was ***-activated mortar with a slag-to-fly ash ratio of 3:1 had the least sorptivity compared to the two other binder combinations,at each curing age,and for mortars made with each of the NaOH alkaline activator *** sorptivity decreased with age and sodium hydroxide concentrations,suggesting the production of geopolymerization *** reduction in weight of sample occurred after immersion in the strong acid H_(2)SO_(4)solution for three months,regardless of binder *** was due to the synthesis of hydration and geopolymerization products in the presence of curing water,which outweighed the degradation of the geopolymer matrix caused by sulfuric acid.

关键词： alkali-activated materials fly ash sorptivity durability of concrete sodium hydroxide sodium silicates reduction in CO_(2)emissions sulfuric acid

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Investigation for Uranium Dispersion Adjacent to Cretaceous Phosphatic Outcrops in al-Nassrieh Basin, Southern Palmyrides, Syria

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Journal of Earth Science 2016年第5期27卷 786-795页

作者： Mohamed al-Hilal Ahmad al-ali Department of Geology the Atomic Energy Commission of Syria (AECS)

A detailed radiometric survey including soil gas radon measurements and field gammaray survey, in accordance with geochemical and geological investigations were carried out in alNassrieh Basin（central Syria）, for the purpose of uranium exploration. Thirty-six samples were collected from various lithofacies of the survey area and analyzed by γ-ray spectrometric technique for determining the concentration values of major radioelements. The relationships between the concentrations of equivalent e U, e Th, and their ratios were examined in order to define their trend of variations and evaluate the degree of uranium remobilization and redistribution. although the initial results indicate that uranium enrichment is mostly restricted to the Upper Cretaceous phosphate rocks, a considerable portion of uranium appeared to be leached out of the primary phosphatic source and dispersed in the adjacent recent sediments. Further, notable increases of radon level associated with relatively high values of uranium concentration and gamma count rates were found to be spatially correlated with the transition zone between the marine Paleogene and continental Neogene formations throughout the study basin. This observation demonstrates the importance of the concerned zone as a suitable geological environment for hosting probable uranium mineralization along a chemically reducing interface where surface water of terrestrial and marine origin mingled at depth and away from surficial conditions.

关键词： radiometric survey geochemistry uranium exploration AI-Nassrieh Basin Syria.

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Soil substrate as a cascade of capillary barriers for conserving water in a desert environment:lessons learned from arid nature

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Journal of Arid Land 2014年第6期6卷 690-703页

作者： ali al-MAKTOUMI Said al-ISMAILY Anvar KACIMOV Hamed al-BUSAIDI Said al-SAQRI Mansour al-HADABI Department of Soils Water and Agricultural EngineeringSultan Qaboos UniversityPO Box 34 Al Khoud 123MuscatSultanate of Oman EcOman Centre Petroleum Development Oman LLC PO Box 81MuscatSultanate of Oman

Interaction between soil pedogenesis, subsurface water dynamics, climate, vegetation and human ingenuity in a desert environment has been found to result in a unique ecohydrological system with an essentially three dimensional sedimentation structure in the bed of a recharge dam in Oman. A 3-D array of silt blocks sand- wiched by dry sand-filled horizontal and vertical fractures was studied in pot experiments as a model of a natural prototype. Pots are filled with a homogenous sand-silt mixture （control） or artificially structured （smart design, SD） soil substrates. Rhodes grass and ivy （Ipomea, Convolvulaceae） were grown in the pots during the hottest season in Oman. Soil moisture content （SMC） was measured at different depths over a period of 20 days without irrigation. SD preserved the SMC of the root zone for both ivy and grass （SMC of around 25%-30% compared to 〈10% for control, 3 days after the last irrigation）. Even after 20 days, SMC was around 18% in the SD and 7% in the control. This, similar to the case of a natural prototype, is attributed to the higher upward capillary movement of water in control pots and intensive evaporation. The capillary barrier of sand sheaths causes discontinuity in moisture mi- gration from the micro-pores in the silt blocks to sand pores. The blocks serve as capillarity-locked water buffers, which are depleted at a slow rate by transpiration rather than evaporation from the soil surface. This creates a unique ecosystem with a dramatic difference in vegetation between SD-pots and control pots. Consequently, the Noy-Meir edaphic factor, conceptualizing the ecological impact of 1-D vertical heterogeneity of desert soils, should be generalized to incorporate 3-D soil heterogeneity patterns. This agro-engineering control of the soil substrate and soil moisture distribution and dynamics （SMDaD） can be widely used by desert farmers as a cheap technique, with significant savings of irrigation water.

关键词： soil capillary barrier infiltration soil heterogeneity ecohydrology hydropedology plant root soil moisture content

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Charged Particles Capture Cross-section by a Weakly Charged Schwarzschild Black Hole

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Research in Astronomy and Astrophysics 2024年第8期24卷 141-146页

作者： A.M.al Zahrani A.al-Jama Physics Department King Fahd University of Petroleum and MineralsDhahran 31261Saudi Arabia

We study the capture cross-section of charged particles by a weakly charged Schwarzschild black *** dependence of the maximum impact parameter for capture on the particle’s energy is investigated numerically for different values of the electromagnetic coupling strength between the particle and the black *** capture cross-section is then *** show that the capture cross-section is independent of the electromagnetic coupling for ultra-relativistic *** astrophysical implications of our results are discussed.

关键词： stars black holes-accretion-accretion disks-black hole physics

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CATIONIC RING-OPENING POLYMERIZATION OF TETRAHYDROFURAN WITH KEGGIN-TYPE HETEROPOLYCOMPOUNDS AS SOLID ACID CATalYSTS

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Chinese Journal of Polymer Science 2010年第3期28卷 305-310页

作者： Ahmed Aouissi Salim Salem al-Deyab Hassan al-Shehri Chemistry Department College of ScienceKing Saud UniversityRiyadhKSA

Three Keggin-type heteropolyanions, namely H3PMo12O40-13H2O, （NH4）3PMo12O40·4H2O and H3PW12O40·13H2O were prepared and tested in the ring-opening polymerization reaction of tetrahydrofuran. The effects of the counter-cation （H＋, NH4＋） and the peripheral atoms （Mo, W） on the polymerization were investigated. It has been found that when the protons of H3PMo12O40·13H2O were replaced by the ammonium cations the polymerization rate decreased dramatically. Whereas, when the peripheral atoms （Mo） were replaced by their homologous （W）, the polymerization rate increased twofold. As for the viscosity average molecular weight （My） of polymer products, it was found that the high molecular weight （7930） was obtained by using H3PW12O40·13H2O. The molecular weight （My） obtained by H3PMo12O40·13H2O and （NH4）H3PMo12O40·13H2O was 6470 and 6810, respectively.

关键词： Tetrahydrofuran Heteropoly compounds Ring opening polymerization Cyclic ether Solid acid

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Singular integral operators on product domains along twisted surfaces

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Frontiers of Mathematics in China 2021年第1期16卷 13-28页

作者： Ahmad al-SalMAN Department of Mathematics Sultan Qaboos UniversitySultanateOman Department of MathematicsYarmouk UniversityIrbidJordan

We introduce a class of singular integral operators on product domains along twisted *** prove that the operators are bounded on L^(p) provided that the kernels satisfy weak conditions.

关键词： Singular integral operators on product domains rough kernels L^(p)estimates Hardy Littlewood maximal function truncated maximal singular integrals twisted surfaces block spaces

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Characters of Nummulites multiplicutiospiralis *** the Qarara Formation,Maghagha,Nile Valley,Egypt

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Acta Geologica Sinica(English Edition) 2021年第2期95卷 342-347页

作者： Safia al MENOUFY University of Ain Shams Faculty of EducationDepartment of Biological&Geological SciencesCairo11341Egypt

Nummulites multiplicutiospiralis *** described and illustrated for both generations from a claystone of Lutetian age in the Middle Eocene Qarara Formation,Maghagha,Nile valley,*** considered to be Nummulites gizehensis,we describe this form as a new species based on diameter of the test and protoconch sizes,septal shape and *** primary feature of this species is spiral multiplication,seen in spiral *** species is also characterized morphologically by lenticular to flat tests with rounded periphery,wrinkled to broadly meandering septal filaments and few granules on the periphery in microspheric *** granules are spirally arranged on the septal filaments in megalospheric *** are longer than high and the spire is *** new taxon belongs to the Nummulites partschi Group,Subgroup *** coiling in the spiral may develop through ontogeny as in ***,the species which was considered to be an index species in the southern Tethys(Boukhary et al.,1982 and Boukhary et al.2010).The characters of the new species,as well as its retrogenesis and reflexive coiling,should be further studied in general in Nummulites spp.,to understand the importance of such characters phylogenetically.

关键词： invertebrate paleontology foraminifera Nummulites Eocene Nile Valley Egypt

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On the Basis of Taiji Relativity

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Chinese Physics Letters 1996年第5期13卷 321-324页

作者： al Xiao-bai Institute of Nuclear Research Chinese Academy of SciencesShanghai 201800

In this letter author argues that the taiji relativity,which recently developed by Hsu et al.[***.A 196(1994)1],caji not be founded only upon Einstein's first postulate,the principle of *** fact it is still based on t... 详细信息

关键词： letter Einstein relativity

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