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Spin transfer torque in the semiconductor/ferromagnetic structure in the presence of Rashba effect

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Chinese Physics B 2017年第2期26卷 505-511页

作者： Javad Vahedi sahar Ghasab Satoory Department of Physics lslamic Azad University Sari Branch Sari Ira

Spin transfer torque in magnetic structure occurs when the transverse component of the spin current that flows from the nonmagnetic medium to ferromagnetic medium is absorbed by the interface. In this paper, considering the Rashba effect on the semiconductor region, we discuss the spin transfer torque in semiconductor/ferromagnetic structure and obtain the components of spin-current density for two models：（i） single electron and（ii） the distribution of electrons. We show that no matter whether the difference in Fermi surface between semiconductor and Fermi spheres for the up and down spins in ferromagnetic increases, the transmission probability decreases. The obtained results for the values used in this article illustrate that Rashba effect increases the difference in Fermi sphere between semiconductor and Fermi sphere for the up and down spins in ferromagnetic. The results also show that the Rashba effect, brings an additional contribution to the components of spin transfer torque, which does not exist in the absence of the Rashba interaction. Moreover, the Rashba term has also different effects on the transverse components of the spin torque transfer.

关键词： spin transfer torque Rashba interaction ferromagnetic

Improving the seismic torsional behavior of plan-asymmetric,single-storey,concrete moment resisting buildings with fluid viscous dampers

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Earthquake Engineering and Engineering Vibration 2016年第1期15卷 61-78页

作者： Fayaz Rahimzadeh Rofooei sahar Mohammadzadeh Civil Engineering Department Sharif University of Technology

The optimal distribution of fluid viscous dampers（FVD）in controlling the seismic response of eccentric,single-storey,moment resisting concrete structures is investigated using the previously defined center of damping constant（CDC）.For this purpose,a number of structural models with different one-way stiffness and strength eccentricities are *** nonlinear time history analyses are carried out for various arrangements of *** is shown that the arrangement of FVDs for controlling the torsional behavior due to asymmetry in the concrete structures is very dependent on the intensity of the peak ground acceleration（PGA）and the extent of the structural stiffness and strength *** results indicate that,in the linear range of structural behavior the stiffness eccentricity es which is the main parameter in determining the location of optimal CDC,is found to be less or smaller than the optimal damping constant eccentricity e＊d,i.e.,｜e＊d｜〉｜es｜.But,in the nonlinear range of structural behavior where the strength eccentricity er is the dominant factor in determining the location of optimal CDC,｜e＊d｜〉｜er｜.It is also concluded that for the majority of the plan-asymmetric,concrete structures considered in this study with er ≠ 0,the optimal CDC approaches the center of mass as er decreases.

关键词： plan-asymmetric concrete buildings torsion fluid viscous dampers weak torsional balance nonlinear timehistory analysis

Investigation on the Local Scour Beneath Piggyback Pipelines Under Clear-Water Conditions

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China Ocean Engineering 2021年第3期35卷 422-431页

作者： sahar ASRARI Habib HAKIMZADEH Nazila KARDAN Faculty of Civil Engineering Sahand University of TechnologySahandIran Department of Civil Engineering Azarbaijan Shahid Madani UniversityTabrizIran

A piggyback pipeline consists of two pipes such that the secondary line rides on the main pipe with a fixed distance between two pipes in *** novel strategy is utilized in offshore areas instead of a single flow *** this regard,there are only a handful of experimental and numerical studies investigating the effect of scour below a piggyback pipeline under steady ***,this study focuses on examining the influential factors on scouring due to steady current including the pipe diameter and the gap between pipes through numerical simulations and experimental ***,at the first phase of the research,a single pipe was established and tested in laboratory to compare the results with those of an empirical *** finishing experimental verifications,piggyback pipelines were also assembled to study the scouring under steady current *** was concluded that by increasing the gap distance between the pipes,the maximum scour depth decreases;however,an increase in the small pipe’s diameter results in a larger maximum scour ***,numerical simulations were carried out using the FLOW-3D software which was found to be a suitable tool for the numerical investigation of this ***,the numerical results have been compared with the corresponding experimental data and a relatively good agreement was achieved between them.

关键词： local scour piggyback pipeline scour depth numerical simulation

Location of Disaster Management Bases Using Spatial Analysis

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Journal of Systems Science and Systems Engineering 2024年第1期33卷 1-29页

作者： Hadi Nayyeri sahar Zandi Mahmood Souri Department of Geomorphology Faculty of Natural ResourceUniversity of KurdistanSanandajKurdistanIran Department of Geography Sciences Kharazmi UniversityTehranIran Red Crescent Society of the Islamic Republic Employee of Iran HamedanIran

Pre-crisis management involves the optimal selection of relief and rescue centers to minimize *** is particularly vulnerable due to its location on the Alpine-Himalaya seismic belt,resulting in an average death rate six times higher than the global average during ***,selecting appropriate relief and rescue centers is crucial to Iran’s disaster *** selecting the placement of rescue centers,accessibility and the appropriateness of the land should be taken into account as well as the distance from high-risk *** location of these centers does not require any particular *** address this issue,a study was conducted utilizing GIS,artificial neural networks,fuzzy logic,and mathematical models to determine the optimal placement based on 12 indicators within two clusters:natural and *** examine the information layers of the initial stage,a spatial data repository concerning the variables impacting the placement of these centers was established using *** functions and algorithms such as Fuzzy Logic in IDRISI,TOPSIS,and VIKOR software,the layers were assessed for weightage before being *** study’s analysis of the models used revealed that the positioning priority limits of the areas differed across all four ***,the areas with high desirability varied to a greater extent:the fuzzy model varied by 9.3%,neural network by 12.4%,VIKOR by 4.5%,and TOPSIS by 16.2%.The variance in results can be attributed to the differing levels of risk acceptance and non-acceptance in each ***,the study yielded other significant findings such as the correlation between study area size and model ***,smaller study areas exhibited higher model *** research also demonstrated that both fuzzy and VIKOR models achieved greater *** a result,employing these models in crisis management planning,particularly in pre-crisis management for identifying rescue center lo

关键词： Crisis management GIS earthquake risk site selection

Synthesis and Characterization of Heterocyclic Functionalized Polymers by Click Reaction: Preparation of Magnetic Nanocomposites and Studies on Their Thermal, Mechanical, Photophysical and Metal Ions Removal Properties

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Chinese Journal of Polymer Science 2015年第2期33卷 301-317页

作者： Mousa Ghaemy sahar Shabzendedar Mehdi Taghavi Polymer Chemistry Research Laboratory Department of Chemistry University of Mazandaran

This work reports synthesis and characterization of heterocyclic functionalized polymers, poly（triazole-etherimidazole）s（PTAEI）, from a dialkyne-terminated compound, 3-（4,5-bis（4-（propargyloxy）phenyl）-1H-imidazol-2-yl）-9-ethyl-9H-carbazole, by using click reaction. PTAEIs were characterized and their properties such as solubility, thermal, mechanical, photophysical and metal ions adsorption were investigated. These polymers had weight average molar masses（Mw） in the range of 19100-26700 g/mol, exhibited excellent solubility in polar aprotic solvents and formed low-colored flexible thin films by solution casting method. They exhibited good thermal stability with glass transition temperatures（Tg） between 160 °C and 211 °C and 10% weight loss temperatures（T10%） in the range of 308-426 °C. Nanocomposites of PTAEIs with epoxide-terminated Fe3O4 showed that strong interfacial interaction between inorganic particles and the polymer matrix contributed to the enhanced thermal and mechanical properties. The photoluminescence intensity of the PTAEIs increased and the spectra red shifted with increasing Fe3O4 content. The PTAEIs and nanocomposites were tested for their extraction capability of metal ions from aqueous solutions either individually or in the mixture.

关键词： Click chemistry Heterocylic polymer Poly(triazole-ether-imidazole) Magnetic nanocomposite Metal ion removal

Design aspect of a novel L-shaped pulsed column for liquid–liquid extraction applications: Energy consumption and the characteristics velocity concept

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Chinese Journal of Chemical Engineering 2018年第4期26卷 723-730页

作者： Pouria Amani Elham Mohammadi sahar Akhgar School of Chemical Engineering College of Engineering University of Tehran Chemical Engineering Department Tarbiat Modares University

This article deals with the evaluation of the consumption of energy for a steady state solvent extraction in a novel L-shaped pulsed sieve-plate column, which is highly required for design and optimization of the periodic flow processes for industrial applications. In this regard, a comprehensive evaluation on the energy consumption in case of a pulsed flow for three different chemical systems is conducted and besides the influence of pulsation intensity, the effect of geometrical parameters including the plate spacing and the plate free area is investigated as well. Moreover, the concept of characteristic velocity models at flooding points is evaluated with respect to the variation of pressure drop along the column at different operational conditions.

关键词： Solvent extraction Pulsed plate column Pressure drop Energy consumption Pulsed flow Characteristic velocity

A regional suspended load yield estimation model for ungauged watersheds

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Water Science and Engineering 2018年第4期11卷 328-337页

作者： Hossein Kheirfam sahar Mokarram-Kashtiban Department of Environmental Science Urmia Lake Research Institute Urmia University Department of Forestry Tarbiat Modares University

Developing regional models using physiographic, climatic, and hydrologic variables is an approach to estimating suspended load yield(SLY)in ungauged watersheds. However, using all the variables might reduce the applicability of these models. Therefore, data reduction techniques(DRTs), e.g., principal component analysis(PCA), Gamma test(GT), and stepwise regression(SR), have been used to select the most effective variables. The artificial neural network(ANN) and multiple linear regression(MLR) are also common tools for SLY modeling. We conducted this study(1) to obtain the most effective variables influencing SLY through DRTs including PCA, GT, and SR, and then, to use them as input data for ANN and MLR; and(2) to provide the best SLY models. Accordingly, we used 14 physiographic, climatic, and hydrologic parameters from 42 watersheds in the Hyrcanian forest region(in northern Iran). The most effective variables as determined through DRTs as well as the original data sets were used as the input data for ANN and MLR in order to provide an SLY model. The results indicated that the SLY models provided by ANN performed much better than the MLR models, and the GT-ANN model was the best. The determination of coefficient,relative error, root mean square error, and bias were 99.9%, 26%, 323 t/year, and 6 t/year in the calibration period, and 70%, 43%, 456 t/year, and 407 t/year in the validation period, respectively. Overall, selecting the main factors that influence SLY and using artificial intelligence tools can be useful for water resources managers to quickly determine the behavior of SLY in ungauged watersheds.

关键词： Data reduction techniques Forest watershed Sediment yield Regional models Watershed sediment modeling

Optimum alternate material selection methodology for an aircraft skin

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Chinese Journal of Aeronautics 2023年第7期36卷 476-488页

作者： Fareed AHMAD Mohammed Al AWADH sahar NOOR Industrial Engineering Department University of Engineering and TechnologyPeshawar 25000Pakistan Department of Industrial Engineering College of EngineeringKing Khalid UniversityAbha 62529Saudi Arabia

Weight penalty has been a challenge for design engineers of aerospace ***’s high-efficiency combat aircraft undergoes intense stress and strain during flying missions,which require stronger and stiffer materials to retain structural *** metallic materials have been successfully used for the construction of aircraft structures and components,metals still have a low strength-to-weight *** paper aims to develop an alternate optimised material selection methodology to replace the metallic skin of a medium-sized military *** search for the optimum material will result in reduced aircraft weight which will be benefitted by extra payload on the *** selection methodology is comprised of finding design pressure limits on the aircraft skin,and comparison of properties(strength,elastic modulus,shear modulus,etc.)and performance(safety factor,deflection,and stress)of the existing metallic skin with alternate optimised *** comparison was made under aerodynamic pressure,bending force,and twisting *** Fibre Reinforced Polymer/Epoxy(CFRP)Uni-Directional(UD)prepreg(elastic modolus is 209 GPa)was selected as an alternate optimum material to replace the aluminium alloy skin of the aircraft *** selected alternate optimum material resulted in the reduction of aircraft skin weight by 30%.

关键词： Aircraft skin Carbon Fibre Reinforced Plastic(CFRP) Material index Material selection methodology Optimum material

Phytochemical Estimation and Therapeutic Amelioration of Aesculus hippocastanum L. Seeds Ethanolic Extract in Gastric Ulcer in Rats Possibly by Inhibiting Prostaglandin Synthesis

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Chinese Journal of Integrative Medicine 2023年第9期29卷 818-824页

作者： sahar Idris Anuradha Mishra Mohammad Khushtar Faculty of Pharmacy Integral UniversityDasauliLucknow226026Uttar PradeshIndia Amity Institute of Pharmacy LucknowAmity University Uttar PradeshNoida201313India

Objective To quantify phytochemicals using liquid chromatography and mass spectroscopy(LCMS)analysis and explore the therapeutic effect of Aesculus hippocastanum L.(AH)seeds ethanolic extract against gastric ulcers in *** Preliminary phytochemical testing and LCMS analysis were performed according to standard *** treatment,the animals were divided into 7 groups including normal control,ulcer control,self-healing,AH seeds low and high doses,ranitidine and per se *** were orally administered with 10 mg/kg of indomethacin,excluding the normal control group(which received 1%carboxy methyl cellulose)and the per se group(received 200 mg/kg AH seeds extract).The test group rats were then given 2 doses of AH seeds extract(100 and 200 mg/kg,respectively),while the standard group was given ranitidine(50 mg/kg).On the 11th day,rats in all groups were sacrificed,and their stomach was isolated to calculate the ulcer index,and other parameters such as blood prostaglandin(PGE2),tissue superoxide dismutase(SOD),catalase(CAT),malonyldialdehyde(MDA),and glutathione(GSH).All isolated stomach tissues were analyzed for histopathological *** The phytochemical examination shows that the AH seeds contain alkaloids,flavonoids,saponins,phenolic components,and *** analysis confirms the presence of quercetin and *** AH seeds extract showed significant improvement in gastric mucosa conditions after indomethacin-induced gastric lesions(P<0.01).Further marked improvement in blood PGE2 and antioxidant enzymes,SOD,CAT,MDA and GSH,were observed compared with self-healing and untreated ulcer-induced groups(P<0.01).Histopathology results confirmed that AH seeds extract improved the mucosal layer and gastric epithelial membrane in treated groups compared to untreated ulcer-induced *** LCMS report confirms the presence of quercetin and rutin in AH seeds ethanolic *** therapeutic effect of AH seeds extract against indomethacin

关键词： Aesculus hippocastanum L. pharmacological action phytochemical physicochemical analysis liquid chromatography and mass spectroscopy analysis gastro-protective activity