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Nonlinear vibration of Timoshenko FG porous sandwich beams subjected to a harmonic axial load

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 649-662页

作者： Milad Lezgi Moein Zanjanchi Nikoo majid Ghadiri Department of Civil Engineering Sharif University of TechnologyTehran ***Iran Civil Engineering Department K.N.Toosi University of TechnologyTehran ***Iran Faculty of Engineering Department of MechanicsImam Khomeini International UniversityQazvin ***Iran

In this study,the instability and bifurcation diagrams of a functionally graded(FG)porous sandwich beam on an elastic,viscous foundation which is influenced by an axial load,are investigated with an analytical *** do so,the Timoshenko beam theory is utilized to take the shear deformations into account,and the nonlinear Von-Karman approach is adopted to acquire the equations of ***,to turn the partial differential equations(PDEs)into ordinary differential equations(ODEs)in the case of equations of motion,the method of Galerkin is employed,followed by the multiple time scale method to solve the resulting *** impact of parameters affecting the response of the beam,including the porosity distribution,porosity coefficient,temperature increments,slenderness,thickness,and damping ratios,are explicitly *** is found that the parameters mentioned above affect the bifurcation points and instability of the sandwich porous beams,some of which,including the effect of temperature and porosity distribution,are less noticeable.

关键词： sandwich beam Timoshenko beam parametric excitation bifurcation diagrams dynamic instability

Sensitivity of optimal double-layer grid designs to geometrical imperfections and geometric nonlinearity conditions in the analysis phase

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Frontiers of Structural and Civil Engineering 2024年第8期18卷 1209-1224页

作者： Amirali REZAEIZADEH Mahsa ZANDI majid ILCHI GHAZAAN School of Civil Engineering Iran University of Science and TechnologyTehran 16846-13114Iran

This study focuses on exploring the effects of geometrical imperfections and different analysis methods on the optimum design of Double-Layer Grids(DLGs),as used in the construction industry.A total of 12 notable metaheuristics are assessed and contrasted,and as a result,the Slime Mold Algorithm is identified as the most effective approach for size optimization of *** evaluate the influence of geometric imperfections and nonlinearity on the optimal design of real-size DLGs,the optimization process is carried out by considering and disregarding geometric nonlinearity while incorporating three distinct forms of geometrical imperfections,namely local imperfections,global imperfections,and combinations of *** light of the uncertain nature of geometrical imperfections,probabilistic distributions are used to define these imperfections randomly in direction and *** results demonstrate that it is necessary to account for these imperfections to obtain an optimal ***’s worth noting that structural imperfections can increase the maximum stress ratio by up to 70%.The analysis also reveals that the initial curvature of members has a more significant impact on the optimal design of structures than the nodal installation error,indicating the need for greater attention to local imperfection issues in space structure construction.

关键词： double-layer grid sizing optimization metaheuristic algorithms geometrical imperfections analysis approach

Reinforcing the management of type 1 gastric esophageal varices

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World Journal of Gastroenterology 2024年第19期30卷 2615-2617页

作者： Zain majid Ghazi Abrar Department of Gastroenterology Sindh Institute of Urology and TransplantationKarachi 75500Pakistan

Variceal bleed represents an important complication of cirrhosis,with its presence reflecting the severity of liver *** varices,though less frequently seen than esophageal varices,present a distinct clinical challenge due to its higher intensity of bleeding and associated *** upon the Sarin classification,GOV1 is the most common subtype of gastric varices seen in clinical practice.

关键词： Gastric varices Sarin classification Gastroesophageal varices Cyanoacrylate Endoscopic variceal ligation Trans jugular intrahepatic portosystemic shunt

Energy evolution and structural health monitoring of coal under different failure modes:An experimental study

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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 917-928页

作者： Yarong Xue Xueqiu He Dazhao Song Zhenlei Li majid Khan Taoping Zhong Fei Yang School of Civil and Resources Engineering University of Science and Technology BeijingBeijing 100083China Zhong-an Academy of Safety Engineering Beijing 100083China

Structural instability in underground engineering,especially in coal-rock structures,poses significant safety ***,the development of an accurate monitoring method for the health of coal-rock bodies is *** focus of this work is on understanding energy evolution patterns in coal-rock bodies under complex conditions by using shear,splitting,and uniaxial compression *** examine the changes in energy parameters during various loading stages and the effects of various failure modes,resulting in an innovative energy dissipation-based health evaluation technique for *** results show that coal bodies go through transitions between strain hardening and softening mechanisms during loading,indicated by fluctuations in elastic energy and dissipation energy *** tensile failure,the energy profile of coal shows a pattern of “high dissipation and low accumulation” before peak *** the other hand,shear failure is described by “high accumulation and low dissipation” in energy *** failure modes correlate with an accelerated increase in the dissipation energy before destabilization,and a significant positive correlation is present between the energy dissipation rate and the stress state of the coal samples.A novel mathematical and statistical approach is developed,establishing a dissipation energy anomaly index,W,which categorizes the structural health of coal into different danger *** method provides a quantitative standard for early warning systems and is adaptable for monitoring structural health in complex underground engineering environments,contributing to the development of structural health monitoring technology.

关键词： energy dissipation structural health monitoring early warning coal-rock mechanics failure mode

Design parameter optimization method for a prestressed steel structure driven by multi-factor coupling

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 1066-1083页

作者： Guo-Liang SHI Zhan-Sheng LIU De-Chun LU Qing-Wen ZHANG majid DEZHKAM Ze-Qiang WANG Faculty of Architecture Civil and Transportation EngineeringBeijing University of TechnologyBeijing 100124China The Key Laboratory of Urban Security and Disaster Engineering of the Ministry of Education Beijing University of TechnologyBeijing 100124China Beijing Building Construction Research Institute Co. Ltd.Beijing 100039China

To achieve efficient structural design,it is crucial to reduce the cost of materials while ensuring structural *** study proposes an optimization method for design parameters(DPs)in a prestressed steel structure driven by multi-factor *** accomplish this,a numerical proxy model of prestressed steel structures is established with integration of DPs and mechanical parameters(MPs).A data association-parameter analysis-optimization selection system is established.A correlation between DPs and MPs is established using a back propagation(BP)neural *** correlation provides samples for parameter analysis and optimization *** are used to characterize the safety of the *** on the safety grade analysis,the key DPs that affect the mechanical properties of the structure are obtained.A mapping function is created to match the MPs and the key *** optimal structural DPs are obtained by setting structural materials as the optimization objective and safety energy as the constraint *** theoretical model is applied to an 80-m-span gymnasium and verified with a scale test physical *** MPs obtained using the proposed method are in good agreement with the experimental *** with the traditional design method,the design cycle can be shortened by more than 90%.Driven by the optimal selection method,a saving of more than 20% can be achieved through reduction of structural material ***,the cross-sectional dimensions of radial cables have a substantial influence on vertical *** initial tension and cross-sectional size of the upper radial cable exhibit the most pronounced impact on the stress distribution in that *** initial tension and cross-sectional size of the lower radial cable hold the greatest sway over the stress distribution in that cable.

关键词： structure design association relationship performance analysis optimum selection experimental verification

Effect of prisms on visual acuity,contrast sensitivity and nystagmus in patients with albinism

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International Journal of Ophthalmology(English edition) 2024年第10期17卷 1864-1868页

作者： Maryam Dashti Abbas Riazi majid Ashrafi Saeed Rahmani Seyyed Mehdi Tabatabaei Department of Optometry School of RehabilitationShahid Beheshti University of Medical SciencesTehran ***Iran Department of Optometry School of RehabilitationIran University of Medical SciencesTehran ***Iran Department of Audiology School of RehabilitationShahid Beheshti University of Medical SciencesTehran ***Iran School of Rehabilitation Shahid Beheshti University of Medical SciencesTehran ***Iran

AIM:To investigate the effect of using base-out prisms on nystagmus,visual acuity and contrast sensitivity in patients with ***:In this interventional study,patients with albinism who had nystagmus were enrolled.A comprehensive eye exam was conducted,which included refraction,assessment of far and near vision acuity,and contrast sensitivity *** check for the nystagmus,a videonystagmography was *** tests were carried out in three modes:without any correction,with optical correction,and with correction using base-out prisms in three different powers,including 4,6,and 8 prism ***:Totally 23 patients with average age of 28.65±12.13 were *** was found that the use of optical correction and optical correction with prisms resulted in a statistically significant improvement in both far(at least:P<0.006)and near visual acuity(at least:P<0.001 except for prism 8;P<0.02).In addition,contrast sensitivity significantly improved at all low and medium frequencies except for correction with prism 8 in frequency 1.5(at least:P<0.01 except for prism 4,frequency 6;P=0.04).no significant improvement was observed in the evaluation of nystagmus ***:Optical correction with a prism can improve visual acuity and some spatial frequencies,but failed to improve nystagmus parameters.

关键词： nystagmus albinism prism

Quantifying glacier surging and associated lake dynamics in Amu Darya river basin using UAV and remote sensing data

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Journal of Mountain Science 2024年第9期21卷 2967-2985页

作者： SAFAROV Mustafo KANG Shichang MURODOV Murodkhudzha BANERJEE Abhishek NAVRUZSHOEV Hofiz GULAYOZOV majid FAZYLOV Ali VOSIDOV Firdavs Key Laboratory of Cryospheric Science and Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Research Center for Ecology and Environment of Central Asia(Dushanbe) Dushanbe 734063Tajikistan University of Chinese Academy of Sciences Beijing 100049China Xinjiang Institute of Ecology and Geography Chinese Academy of SciencesUrumqi 830011China Mountain Societies Research Institute University of Central AsiaDushanbe 734000Tajikistan State Scientific Institution“Center for Research of Glaciers of the National Academy of Sciences of Tajikistan” Dushanbe 734025Tajikistan Institute of Water Problems Hydropower and Ecology of the National Academy of Sciences of TajikistanDushanbe 734025Tajikistan

Glaciers in the Pamir region are experiencing rapid melting and receding due to climate change,which has a significant implication for the Amu Darya river ***,surging glaciers,which undergo unpredictable advances,are potentially leading to the obstruction of high-altitude river channels and also glacial lake outburst *** of-703.5±30.0 *** is a substantial increase in the number(from 19 to 75)and area(from 4889.7±0.6 m2 to 15345.5±0.6 m2)of RGS lakes along with supra-glacier ponds based on a comparison of ArcGIS base map in 2011 and high-resolution UAV data in *** M glacier,number of lakes increased from 4 to 22 but the lake area declined from 10715.2±0.6 to 365.6±0.6 *** was noted that the largest lake in 2011 with an area of 10406.4±0.6 m2 at the southeastern portion of the glacier was not observed in 2023 due to *** the glaciers have substantially impacted the river flow(Abdukahor river)by obstructing a significant proportion of river channel in recent years and might cause outburst *** findings enhance the understanding of glacier dynamics and their impacts on the surrounding areas,emphasizing the urgent need for continued monitoring and appropriate management strategies,with a specific focus on surging glaciers and the associated risks.

关键词： UAV Remote sensing Climate change Glacier dynamics Google Earth Engine Pamir

应用欧拉-拉格朗日方法分析动脉粥样硬化性颈动脉血流的流-固相互作用

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Journal of Central South University 2024年第1期31卷 151-168页

作者： majid SIAVASHI Ava BINA Mojtaba SAYADNEJAD Borhan BEIGZADEH Applied Multi-Phase Fluid Dynamics Lab. School of Mechanical EngineeringIran University of Science and TechnologyTehranIran Biomechatronics and Cognitive Engineering Research Lab. School of Mechanical EngineeringIran University of Science and TechnologyTehranIran

本研究旨在模拟不同狭窄程度和脉搏率的颈动脉搏动血流。采用流-固耦合(FSI)和任意拉格朗日-欧拉(ALE)方法研究了不同狭窄程度、脉搏率和动脉壁性质对周围流体的影响。分别应用Carreau-Yasuda非牛顿超弹性模型和修正Mooney-Rivin超弹性... 详细信息

本研究旨在模拟不同狭窄程度和脉搏率的颈动脉搏动血流。采用流-固耦合(FSI)和任意拉格朗日-欧拉(ALE)方法研究了不同狭窄程度、脉搏率和动脉壁性质对周围流体的影响。分别应用Carreau-Yasuda非牛顿超弹性模型和修正Mooney-Rivin超弹性模型于具有非牛顿行为的血液和超弹性血管壁。结果得到血液的壁面径向位移、压力分布、轴向速度分布和壁面剪切应力。通过增加狭窄的严重程度,轴向速度、血压变化、最大壁面剪切应力和壁面径向位移均呈增长趋势。当脉率在狭窄程度为75%时,最大流量矩、壁面径向位移、压力、轴向速度和壁面剪应力的最大值均增大。此外,与弹性和刚性模型相比,将动脉壁视为超弹性模型,将其周围流体视为非牛顿和非定常,可以使模拟更加真实。在严重程度高达50%的狭窄中,红细胞受到轻微损害,而在严重程度为75%的狭窄中观察到溶血。通过改善动脉粥样硬化,弹性模量从500 k Pa提高到2 MPa,在60 bpm脉率和狭窄程度75%下,剪切应力最大值增长65%。与刚性和弹性动脉壁相比,动脉壁的超弹性模型导致较低的轴向速度、较低的血压、较低的剪切应力和较高的径向位移。

关键词：流-固耦合狭窄严重程度脉率变化超弹性的动脉动脉粥样硬化

Fe-Ti Oxide Mineralization in the XV Intrusion, Bafq Mining District, Central Iran: Insights from Mineralogy, Mineral Chemistry and S Isotopic Data

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Journal of Earth Science 2024年第5期35卷 1704-1719页

作者： Sakine Amraei majid Ghasemi Siani Mohammad Yazdi Liang Qiu Bertrand Moine Minghua Ren Department of Inorganic Geology and Water Faculty of Earth SciencesShahid Beheshti University Department of Geochemistry Faculty of Earth SciencesKharazmi University State Key Laboratory of Geological Processes and Mineral Resources School of Earth Sciences and ResourcesChina University of Geosciences Université Clermont Auvergne CNRSIRDOPGCLaboratoire Magmas et Volcans Department of Geoscience University of Nevada

The mafic-ultramafic intrusion in the XV anomaly area,contains magmatic Fe-Ti oxides±（p） ore,is located in the Bafq mining district in the Central *** consists of cumulate and layered Fe-Ti-bearing gabbros and *** mineral assemblages include clinopyroxene,Fe-Ti oxides,plagioclase,amphibole,apatite and sulfides（pyrite and chalcopyrite）.The Fe-Ti oxides mainly consist of magnetite-titanomagnetite and ilmenite,which occurred as disseminated,intergrowth,lamellae（trellis and sandwich textures） and *** in the gabbroic rocks is from the near end-member of Fe3O4（<1 wt.%TiO2） to titanomagnetite containing up to 8 wt.%TiO2(about3.73 wt.%to 26.84 wt.%Ulvospinel(XUsp)).Magnetite in pyroxenite rocks is characterized with TiO2range from 0.46 wt.%to 3.14 wt.%(XUspvaried from 1.76 wt.%to 10.46 wt.%).The abundances of V2O3range from 0.03 wt.% to 1.29 wt.%and 0.24 wt.%to 1.00 wt.%for gabbro and pyroxenite,*** of magnetite show insignificant correlations with Al2O3and *** average XIlmin the ilmenite of gabbro is 92%,whereas it is 90.37%in the pyroxenite *** MgO and V2O3contents show a slightly positive correlation with TiO2in *** composition of clinopyroxenes in gabbro and pyroxenite rocks fall in the diopside to augite field with Mg#ranging from 67 to 98 and 74 to 96,*** both rock types,amphiboles are mainly pargasite and rarely *** in pyroxenite rocks is clustered in the labradorite to andesine fields with a compositional ranges of An46-69and in gabboic rocks fall in two fields with compositional ranges of albite with An0.65-5.95and labradorite with *** δ34S isotopic values cover a limited range from +3.15‰ to +4.10‰V-CDT consistent with magmatic ***-Ti mineralization is formed in two stages,minor inclusions of Fe-Ti oxide minerals in the pyroxene and plagioclase crystallized in the early magmatic stage,whereas interstitial oxides formed by fractional crystallizatio

关键词： mafic-ultramafic intrusion Fe-Ti oxides gravitational settling mineral chemistry Bafq mining district Central Iran mineral deposits