检索结果-南通市图书馆

Experimental study on behaviors of polypropylene fibrous concrete beams

Journal of Zhejiang University-science A(Applied Physics & Engineering) 2007年第7期8卷 1101-1109页

作者： sUJI D. NATEsAN s. C. MURUGEsAN R. sathyabama Institute of science and Technology Chennai Tamil Nadu India VLB Janakiammal College of Engineering and Technology Coimbatore Tamil Nadu India Gojan school of Business and Technology Red Hills Chennai Tamil Nadu India

synthetic fibers made from nylon or polypropylene have gained application when loose and woven into geo textile form although no information on the matrix’s mechanical performance is obtained so that more understanding of their structural contribution to resist cracking can be determined. This paper presents the results of an experimental investigation to determine the performance characteristics of concrete reinforced with a polypropylene structural fiber. In this investigation “Fiber mesh” brand of fibers manufactured by sL Concrete system, Tennessee, UsA and marketed by M/s Millennium Building system, Inc., Ban-galore, India are used. The lengths of the fibers used were 24 mm. Fiber dosages used were 0.9, 1.8, 2.7 kg/m3. A total of three mixtures, one for each fiber dosage were made. A standard slump cone test was conducted on the fresh concrete mix with and without fibers to determine the workability of the mix. The test program included the evaluation of hardened concrete properties such as compressive, split tensile, modulus of rupture and flexural strengths. The increase in compressive strength is about 36.25%, 26.20%, and 23.75% respectively that of plain concrete. This increase in strength was directly proportional to amount of fibers present in the mix. The increase in flexural strength for Mixes I^III is about 21%, 16.6%, and 23% respectively that of plain concrete specimens. An experimental investigation was also made to study the behaviors of reinforced fibers concrete beams (with longitudinal reinforcements) under two-point loading. The deflection and crack patterns were also studied. The improvements in strength and ductility characteristics were discussed.

关键词： Fiber Reinforcement Concrete Mechanical properties Polypropylene Fibre Reinforced Concrete (PFRC)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Mathematical model of micropolar fluid in two-phase immiscible fluid flow through porous channel

引用

Applied Mathematics and Mechanics(English Edition) 2018年第7期39卷 993-1006页

作者： P.K.YADAV s.JAIsWAL B.D.sHARMA Department of Mathematics Motilal Nehru National Institute of Technology Allahabad

This paper is concerned with the flow of two immiscible fluids through a porous horizontal channel. The fluid in the upper region is the micropolar fluid/the Eringen fluid, and the fluid in the lower region is the Newtonian viscous fluid. The flow is driven by a constant pressure gradient. The presence of micropolar fluids introduces additional rotational parameters. Also, the porous material considered in both regions has two different permeabilities. A direct method is used to obtain the analytical solu- tion of the concerned problem. In the present problem, the effects of the couple stress, the micropolarity parameter, the viscosity ratio, and the permeability on the velocity profile and the microrotational velocity are discussed. It is found that all the physical parameters play an important role in controlling the translational velocity profile and the microrotational velocity. In addition, numerical values of the different flow parameters are computed. The effects of the different flow parameters on the flow rate and the wall shear stress are also discussed graphically.

关键词： micropolar fluid immiscible fluid porous medium couple stress microp=olarity parameter

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Complex variable approach in studying modified polarization saturation model in two-dimensional semipermeable piezoelectric media

引用

Applied Mathematics and Mechanics(English Edition) 2017年第11期38卷 1517-1532页

作者： s. sINGH K. sHARMA R. R. BHARGAVA Department of sciences and Humanities National Institute of Technology UttarakhandSrinagar(Garhwal)246174India Department of Mathematics Indian Institute of Technology RoorkeeRoorkee 247667India

A modified polarization saturation model is proposed and addressed math- ematically using a complex variable approach in two-dimensional （2D） semipermeable piezoelectric media. In this model, an existing polarization saturation （Ps） model in 2D piezoelectric media is modified by considering a linearly varying saturated normal electric displacement load in place of a constant normal electric displacement load, applied on a saturated electric zone. A centre cracked infinite 2D piezoelectric domain subject to an arbitrary poling direction and in-plane electromechanical loadings is considered for the analytical and numerical studies. Here, the problem is mathematically modeled as a non-homogeneous Riemann-Hilbert problem in terms of unknown complex potential functions representing electric displacement and stress components. Having solved the Hilbert problem, the solutions to the saturated zone length, the crack opening displace- ment （COD）, the crack opening potential （COP）, and the local stress intensity factors （sIFs） are obtained in explicit forms. A numerical study is also presented for the proposed modified model, showing the effects of the saturation condition on the applied electrical loading, the saturation zone length, and the COP. The results of fracture parameters obtained from the proposed model are compared with the existing Ps model subject to electrical loading, crack face conditions, and polarization angles.

关键词： complex variable fracture parameter local stress intensity factor (sIF),piezoelectric polarization saturation (Ps) model

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

synthesis of ZnO Nanoparticles onto sepiolite Needles and Determination of Their sensitivity toward Humidity, NO_2 and H_2

引用

Journal of Materials science & Technology 2016年第6期32卷 573-582页

作者： M.Hassan Ahmed s.Afify J.M.Tulliani Department of Applied science and Technology Politecnico di Torino

This work investigated the sensitivity toward humidity, NO2 and H2 of ZnO modified sepiolite （si12Mg8O30（OH）4.（H2O）4.8H2O）. To this aim, sepiolite powder was first modified by leaching magnesium ions in HCI then by precipitating nano-sized Zn-based compounds under basic conditions. A subse- quent thermal treatment at 550 ℃ for 1 h was performed. The powders were characterized by X-ray diffraction （XRD）, specific surface area measurements, thermogravimetric and differential thermal anal- ysis and field emission scanning electron microscopy, as well as high resolution transmission electron microscopy. The XRD patterns showed that all leached heat treated samples were made of anhydrous sepiolite and of ZnO. sensors were then obtained by screen printing these materials onto commercial alumina substrates with Pt electrodes. All the investigated compositions were capable of detecting NO2 down to ppm level and 20 ppm H2, at an optimal working temperature of 300°C. These detection limits are in line with the current best results reported in literature.

关键词： Clay minerals Gas sensor sensitivity Hydrogen sensor Nitrogen Oxide

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Exact solution for the unsteady flow of a semi-infinite micropolar fluid

引用

Acta Mechanica sinica 2011年第3期27卷 354-359页

作者： H.H. sherief M.s. Faltas E.A. Ashmawy Department of Mathematics Faculty of ScienceAlexandria University

The unsteady motion of an incompressible micropolar fluid filling a half-space bounded by a horizontal infinite plate that started to move suddenly is considered. Laplace transform techniques are used. The solution in the Laplace transform domain is obtained by using a direct approach. The inverse Laplace transforms are obtained in an exact manner using the complex inversion formula of the transform together with contour integration techniques. The solution in the case of classical viscous fluids is recovered as a special case of this work when the micropolarity coecient is assumed to be zero. Numerical computations are carried out and represented graphically.

关键词： Unsteady motion . Laplace transform . Microp-olar fluid

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The vibron dressing in α-helicoidal macromolecular chains

引用

Chinese Physics B 2013年第6期22卷 218-227页

作者： D.evizovi s. Galovi A. Reshetnyak Z. Ivi University of Belgrade Vina Institute of Nuclear Sciences Laboratory for Theoretical and Condensed Matter PhysicsP. O. Box 522 11001 Belgrade Serbia Joint Institute for Nuclear Research Bogoliubov Laboratory for Theoretical Physics Dubna Russia Laboratory of Non-Linear Media Physics Institute of Strength Physics and Materials ScienceTomsk 634021 Russia

We present a study of the physical properties of the vibrational excitation in α-helicoidal macromolecular chains, caused by the interaction with acoustical and optical phonon modes. The influence of the temperature and the basic system parameters on the vibron dressing have been analyzed by employing the simple mean-field approach based on the variational extension of the Lang-Firsov unitary transformation. The applied approach predicts a region in system parameter space where one has an abrupt transition from a partially dressed （light and mobile） to a fully dressed （immobile） vibron state. We found that the boundary of this region depends on system temperature and the type of bond among structural elements in the macromolecular chain.

关键词： vibron small-polaron α-helix partial dressing

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Responses of two cultivars of Trifolium repens L. to ethylene diurea in relation to ambient ozone

引用

Journal of Environmental sciences 2010年第7期22卷 1096-1103页

作者： shalini singh Dalbir Kaur s.B.Agrawal M.Agrawal Laboratory of Air Pollution and Global Climate Change Department of BotanyBanaras Hindu University

Three ethylene diurea （EDU） concentrations （0, 150 and 300 mg/L） were used to evaluate the negative impact of ozone （O3） on two cultivars of Trifoliurn repens L. cv. Vardan and Bundel grown under natural field conditions in a suburban area of Varanasi, India. Mean O3 concentrations varied from 30.3 to 46.6 μg/L during the experimental period. Higher photosynthetic pigments and ascorhic acid concentrations were noticed in both EDU-treated cultivars over non-EDU-treated ones, but a reverse trend was found for lipid peroxidation. Growth parameters and biomass also showed increments under EDU treatment of both cultivars. The ratio of variable fluorescence to maximum fluorescence increased significantly in Vardan but not in Bundel upon EDU treatment. Results revealed that EDU concentration of 300 mg/L was more effective to combat the oxidative stress as well as protecting plants from O3 injury symptoms. The test cultivar Vardan is relatively sensitive to O3, thereby can be used as a bioindicator of O3 pollution in areas having higher O3 concentrations. Results also indicated that Bundel has more efficient antioxidant defense system than Vardan and hence was more tolerant to O3 stress.

关键词： Trifolium repens ozone oxidative stress ascorbic acid photosynthetic pigments

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

FOREIGN DIRECT INVEsTMENT AND ITs IMPACT ON CHINA's ECONOMY: A REsEARCH APPRAIsAL

引用

Journal of Geographical sciences 1997年第1期7卷 33-45页

作者： Xiaojian Li Department of Geography, Henan University, Kaifeng 475001 People’s Republic of China

Foreign direct investment (FDI) and the development of the hosted nations is a major issue facing researchers in many disciplines, especially in economic geography. This paper reviews the current available literature pertaining to the impact of FDI on the economic development in China, and emphasizes four points. First, although China is the second largest of FDI recipient and one of the fastest growing nations in the world, it has not drawn enough attention of researchers on the topic. And very few publications are found specifically focusing on the economic impact of FDI. second, many areas of the impact of FDI have remained untouched. Particularly, there are needs for further studies to address the impact of FDI on efficient use of resources and overall competitiveness of the country. Third, in the theoretical aspect, research should explore the nature of bargaining power of all participants. Finally, it is suggested to select a number of case study areas and foreign funded enterprises for in depth studies.

关键词： Foreign Direct Investment development China.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Asymptotic and numerical study of a surface breaking crack subject to a transient thermal loading

引用

Acta Mechanica sinica 2006年第1期22卷 22-27页

作者： A.B. Movchan I.s. Jones ljmu.ac.uk Department of Mathematical sciencesUniversity of Liverpoo UK L69 3BX school of EngineeringJames Parsons BuildingJohn Moores UniversityByrom st.Liverpool UK. L3 3AF E-mail: i.s.jones

An asymptotic algorithm is applied to the problem of a finite, thermo-elastic solid containing a surface breaking crack, when the exterior surface is subjected to oscillatory thermal loading. This algorithm involves the study of a model problem. An analytical and numerical study of this model problem of a thermo-elastic half space containing a surface breaking crack and subjected to oscillatory thermal loading is presented. The crack surface is traction free. In particular, the amplitude of the stress intensity factor at the crack vertex is found as a function of the crack depth and the frequency of thermal oscillation.

关键词： Thermo-elasticity surface breaking crack Wiener-Hopf solution Weight function method

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Numerical simulation of Vortex Engine Flow Field:One Phase and Two Phases

引用

Journal of Thermal science 2009年第3期18卷 226-234页

作者： A.F.Najafi s.D.saemi M.H.saidi Department of Energy Engineering Power and Water University of Technology Department of Mechanical Engineering Sharif University of Technology

Aiming at improving efficiency in combustion systems, the study on droplet behavior and its trajectory is of crucialimportance. Vortex engine is a kind of internal combustion engine which uses swirl flow to achieve highercombustion efficiency. One of the important advantages of designing vortex engine is to reduce the temperatureof walls by confining the combustion products in the inner vortex. The scopes of this investigation are to studyvortex engine flow field as well as effective parameters on fuel droplet behavior such as droplet diameter, dropletinitial velocity and inlet velocity of the flow field. The flow field is simulated using Reynolds stress TransportModel (RsM). The Eulerian-Lagrangian method and the one-way coupling approach are employed to simulatetwo phase flow and dispersed phase in the chamber, respectively. A new method, based on computing pressureforce exerted on the droplet surface, is introduced to determine the distinction between using one-way andtwo-way coupling approaches. The results showed that the droplets with smaller diameter are more likely to followthe flow stream lines than bigger droplets, thus evaporate completely in the chamber. Moreover, droplets withgreater initial velocity have higher evaporation rate, yielding the existence of evaporation and combustion in theinner vortex. Additionally, the higher inlet velocity of continuous phase results in higher centrifugal force, leadsdroplets in question to deviate towards the wall faster.

关键词： Vortex Engine swirl Flow Lagrangian Approach Fuel Droplet

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：