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Free vibration and buckling analysis of polymeric composite beams reinforced by functionally graded bamboo fbers

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Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 543-562页

作者： h.M.FEIZABAD M.h.yas Department of Mechanical Engineering Razi UniversityKermanshah ***Iran

Natural fibers have been extensively researched as reinforcement materials in polymers on account of their environmental and economic advantages in comparison with synthetic fibers in the recent *** fibers are renowned for their good mechanical properties,abundance,and short cycle *** beams are one of the fundamental structural components and are susceptible to mechanical loads in engineering applications,this paper performs a study on the free vibration and buckling responses of bamboo fiber reinforced composite(BFRC)beams on the elastic *** different functionally graded(FG)layouts and a uniform one are the considered distributions for unidirectional long bamboo fibers across the *** elastic properties of the composite are determined with the law of *** hamilton’s principle,the governing equations of motion are *** generalized differential quadrature method(GDQM)is then applied to the equations to obtain the *** achieved outcomes exhibit that the natural frequency and buckling load values vary as the fiber volume fractions and distributions,elastic foundation stiffness values,and boundary conditions(BCs)and slenderness ratio of the beam ***,a comparative study is conducted between the derived analysis outcomes for BFRC and homogenous polymer beams to examine the effectiveness of bamboo fibers as reinforcement materials,demonstrating the significant enhancements in both vibration and buckling responses,with the exception of natural frequencies for cantilever beams on the Pasternak foundation with the FG-◇fiber ***,the obtained analysis results of BFRC beams are also compared with those for carbon nanotube reinforced composite(CNTRC)beams found in the literature,indicating that the buckling loads and natural frequencies of BFRC beams are lower than those of CNTRC beams.

关键词： bamboo fiber free vibration buckling analysis functionally graded(FG)beam elastic foundation generalized differential quadrature method(GDQM)

Thermal vibration of functionally graded porous nanocomposite beams reinforced by graphene platelets

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Applied Mathematics and Mechanics(English Edition) 2020年第8期41卷 1209-1226页

作者： M.h.yas S.RAhIMI Department of Mechanical Engineering Razi UniversityKermanshah 67346-67149Iran

The thermal vibration of functionally graded(FG)porous nanocomposite beams reinforced by graphene platelets(GPLs)is *** beams are exposed to the thermal gradient with a multilayer *** temperature varies linearly across the thickness *** different types of dispersion patterns of GPLs as well as porosity distributions are *** material properties vary along the thickness *** using the mechanical parameters of closed-cell cellular solid,the variation of Poisson’s ratio and the relation between the porosity coefficient and the mass density under the Gaussian random field(GRF)model are *** using the halpin-Tsai micromechanics model,the elastic modulus of the nanocomposite is *** equations of motion based on the Timoshenko beam theory are obtained by using hamilton’s *** equations are discretized and solved by using the generalized differential quadrature method(GDQM)to obtain the fundamental *** effects of the weight fraction,the dispersion model,the geometry,and the size of GPLs,as well as the porosity distribution,the porosity coefficient,the boundary condition,the metal matrix,the slenderness ratio,and the thermal gradient are presented.

关键词： thermal vibration functionally graded(FG) porous material graphene platelet(GPL) Timoshenko beam

Dynamic and buckling analysis of polymer hybrid composite beam with variable thickness

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Applied Mathematics and Mechanics(English Edition) 2020年第5期41卷 785-804页

作者： S.AFShIN M.h.yas Department of Mechanical Engineering Razi UniversityKermanshah 67149Iran

This work deals with a study of the dynamic and buckling analysis of polymer hybrid composite(PhC) beam. The beam has variable thickness and is reinforced by carbon nanotubes(CNTs) and nanoclay(NC) simultaneously. The governing equations are derived based on the first shear deformation theory(FSDT). A three-phase halpinTsai approach is used to predict the mechanical properties of the PhC. We focus our attention on the effect of the simultaneous addition of NC and CNT on the vibration and buckling analysis of the PhC beam with variable thickness. Also a comparison study is done on the sensation of three impressive parameters including CNT, NC weight fractions, and the shape factor of fillers on the mechanical properties of PhC beams,as well as fundamental frequencies of free vibrations and critical buckling load. The results show that the increase of shape factor value, NC, and CNT weight fractions leads to considerable reinforcement in mechanical properties as well as increase of the dimensionless fundamental frequency and buckling load. The variation of CNT weight fraction on elastic modulus is more sensitive rather than shear modulus but the effect of NC weight fraction on elastic and shear moduli is fairly the same. The shape factor values more than the medium level do not affect the mechanical properties.

关键词： polymer hybrid composite(PhC) halpin-Tsai carbon nanotube(CNT) nanoclay(NC) free vibration buckling load

Three-dimensional free vibration analysis of multi-directional functionally graded piezoelectric annular plates on elastic foundations via state space based differential quadrature method

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Applied Mathematics and Mechanics(English Edition) 2015年第4期36卷 439-464页

作者： M.h.yas N.MOLOUDI Department of Mechanical Engineering Razi University

The three-dimensional free vibration analysis of a multi-directional func- tionally graded piezoelectric （FGP） annular plate resting on two parameter （Pasternak） elastic foundations is investigated under different boundary conditions. The material properties are assumed to vary continuously along the radial and thickness directions and have exponent-law distribution. A semi-analytical approach named the state space based differential quadrature method （SSDQM） is used to provide an analytical solution along the thickness using the state space method （SSM） and an approximate solution along the radial direction using the one-dimensional differential quadrature method （DQM）. The influence of the Winkler and shear stiffness of the foundation~ the material property graded variations, and the circumferential wave number on the nomdimensional natural frequency of multi-directional FGP annular plates is studied.

关键词： multi-directional functionally graded piezoelectric annular plate freevibration

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基于BIPL的Web频繁访问模式挖掘

计算机工程与应用 2008年第23期44卷 136-138,156页

作者：吴雅双张东站厦门大学计算机科学系福建厦门361005

挖掘频繁访问模式是Web日志挖掘的一个重要任务。针对类Apriori算法和GITC算法的不足,提出了基于双亲链的单次扫描求交的Web频繁访问模式挖掘算法—BIPL,该算法首先对用户的访问模式两两进行交集运算,生成候选访问模式,并在求交集过程... 详细信息

挖掘频繁访问模式是Web日志挖掘的一个重要任务。针对类Apriori算法和GITC算法的不足,提出了基于双亲链的单次扫描求交的Web频繁访问模式挖掘算法—BIPL,该算法首先对用户的访问模式两两进行交集运算,生成候选访问模式,并在求交集过程中保存各个候选访问模式的双亲模式,然后通过简单的求和运算,计算出各个候选访问模式的支持数。最后通过理论分析和实验验证,该算法是稳定的和高效的。

关键词： Web日志挖掘交集关系频繁访问模式

a-Si∶h薄膜结构对多晶硅薄膜性能的影响

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功能材料 2000年第2期31卷 157-158页

作者：余楚迎林璇英姚若河吴萍林揆训汕头大学物理系广东汕头515063

用a -Si∶h薄膜经退火晶化成的多晶硅薄膜 ,其晶化温度、晶粒尺寸和电性能与薄膜的初始结构有密切关系 ,而a -Si∶h薄膜的初始结构依赖于沉积条件。用PCVD方法高速沉积的a -Si∶h薄膜 ,经 550℃的低温退火 ,可以制备平均晶粒尺寸为几百n... 详细信息

用a -Si∶h薄膜经退火晶化成的多晶硅薄膜 ,其晶化温度、晶粒尺寸和电性能与薄膜的初始结构有密切关系 ,而a -Si∶h薄膜的初始结构依赖于沉积条件。用PCVD方法高速沉积的a -Si∶h薄膜 ,经 550℃的低温退火 ,可以制备平均晶粒尺寸为几百nm ,最大晶粒尺寸为 2 μm ,电导率为 1.6 2 (Ω·cm ) - 1 的优质多晶硅薄膜。

关键词：多晶硅薄膜衬底温度掺杂比晶化温度晶粒尺寸

Evaluation of toxicity profiles of rare earth elements salts(lanthanides)

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Journal of Rare Earths 2021年第2期39卷 225-232页

作者： M.Rucki K.Kejlov A.Vlkov D.Jirova M.Dvorakova L.Svobodova h.Kandarova S.Letasiova h.Kolarova M.Mannerstrom T.heinonen National Institute of Public health Srobarova 49/4810000 Prague.Czech Republic Centre of Experimental Medicine SAS Slovak Academy of SciencesDubravska Cesta 984104 Bratislava.Slovakia MatTek In Vitro Life Science Laboratories Mlynske Nivy 7382105 BratislavaSlovakia Department of Medical Biophysics Faculty of Medicine and DentistryPalacky UniversityHnevotinska 377515 OlomoucCzech Republic FICAM Faculty of Medicine and Health TechnologyFI-33014 Tampere UniversityTampereFinland

The presented study aims to extend the knowledge of toxicological profile of rare earth elements salts(REEs).The basal toxicity test performed comprised assessment of cytotoxicity(3 T3 Balb/c Neutral Red Uptake Test)that allows for calculation of LD50(rats)on the basis of the concentration which leads to a50%reduction in cell growth(IC50).Environmental toxicity was addressed by the Tubifex tubifex(T.t.)express *** in vitro skin irritation(OECD TG 439)and skin corrosion tests(OECD TG 431)utilizing the 3 D in vitro reconstructed human epidermal model EpiDerm(MatTek IVSL,SK)were used for assessment of skin irritation and corrosion potential hazard of *** effects were determined using the bacterial reverse mutation assay(Ames Test)on 5 Salmonella typhimurium strains with and without metabolic activation(OECD TG 471).Endocrine disruption was evaluated by means of a yeastbased assay YES/yas(Xenometrix,Ch).Skin sensitization was assessed using the LuSens assay,based on a genetically modified human keratinocyte cell line(OECD TG 442 D).The tested REEs have no potential of mutagenicity or skin sensitization,exhibit very weak endocrine disruption potential and only exceptional local irritation/corrosion effects for thulium(Ⅲ)chloride anhydrous,but have acute and chronic toxic effects on the aquatic environment.

关键词： Lanthanides Rare earth elements Local toxicity Systemic toxicity Ecotoxicity

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生活方式干预对脂肪储存库动员的影响

中华高血压杂志 2017年第12期25卷 1199-1199页

作者： Gepner Y Shelef I Schwarzfuchs D Zelicha h Tene L yas-kolka Meir A Tsaban G Cohen N Bril N Rein M Serfaty D Kenigsbuch S Komy O Wolak A Chassidim Y Golan R Avni-hassid h Bilitzky A Sarusi B Goshen E Shemesh E henkin Y Stumvoll M Blüher M Thiery J Ceglarek U Ru-dich A Stampfer MJ Shai I 黄洁叶鹏

该研究的目的是评估不同的生活方式干预能否对身体的脂质储存部位产生不同的影响。方法：研究者在278名腹型肥胖（209名，占75％）或脂质代谢紊乱的成年人中进行了一项为期18个月的随机对照研究，提供午餐并对用餐情况进行监督。

关键词：生活方式干预储存脂质代谢紊乱脂肪随机对照研究腹型肥胖成年人