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Vertex angles effects in the energy absorption of axially crushed kenaf fibre-epoxy reinforced elliptical composite cones

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Defence Technology（防务技术） 2018年第4期14卷 327-335页

作者： Mohamed Alkateb S.M.Sapuan Z.Leman M.R.Ishak Mohammad Jawaid Department of Mechanical and Manufacturing Engineering Universiti Putra Malaysia Laboratory of Bio Composite Technology Institute of Tropical Forestry and Research Products (INTROP)Universiti Putra Malaysia Aerospace Manufacturing Research Centre (AMRC) Universiti Putra Malaysia Departments of Aerospace Engineering Universiti Putra Malaysia

Experimental quasi-static crushing tests were conducted by using a universal testing machine format kenaf-epoxy composite elliptical cones. The work focused on the vertex angle's effects on energy absorption capability; the vertex angles vary from 0° to 24° in 6 increments. The failure modes of the kenaf fibre epoxy composite elliptical cones were observed utilising delegate photos taken during the quasistatic crushing test. Load-deformation curves and deformation histories of typical specimens are presented and discussed. Moreover, the effects of cone vertex angles on the load carrying capacity and the energy absorption capability are also discussed. The results show that the energy absorption abilities significantly influence the ellipticity vertex angle as the load carrying capacity. We concluded that the quasi-static axial crushing behaviour of elliptical mat laminated composite cones is strongly affected by their structural geometry and the specific energy absorbed by the composite elliptical cones with vertex angles of 6°, 12°, 18°, and 24°, which is more than an elliptical cone with the vertex angle of 0°(the elliptical tube) at any given deformation. However, the specific energy absorption for the elliptical composite cone showed a positive correlation, i.e., the more the angle increased, the more energy was absorbed. In this regard, an elliptical composite cone with a 24° angle exhibited the best energy absorption capability.

关键词： Kenaf fibres Composite materials elliptical cone Vertex angle Collapsible Energy absorption

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A comprehensive study of two-phase flow and heat transfer of water/Ag nanofluid in an elliptical curved minichannel

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Chinese Journal of Chemical Engineering 2020年第2期28卷 383-402页

作者： Sajad Mir Omid Ali Akbari Davood Toghraie Ghanbarali Sheikhzadeh Ali Marzban Saeid Mir Pouyan Talebizadehsardari Department of Mechanical Engineering Aligoudarz BranchIslamic Azad UniversityAligoudarzIran Young Researchers and Elite Club Khomeinishahr BranchIslamic Azad UniversityKhomeinishahrIran Department of Mechanical Engineering Khomeinishahr BranchIslamic Azad UniversityKhomeinishahrIran Department of Mechanical Engineering University of KashanKashanIran Department for Management of Science and Technology Development Ton Duc Thang UniversityHo Chi Minh CityVietnam Faculty of Applied Sciences Ton Duc Thang UniversityHo Chi Minh CityVietnam

In this research,laminar flow and heat transfer of two-phase water/Ag nanofluid with 0–6%volume fraction of nanoparticles at Re=150–700 in a curved geometry are simulated using finite volume method.Studied geometry is an elliptical curved minichannel with curvature angle of 180°.Forced and natural flow of two-phase nanofluid is simulated at Gr=15000,35000 and 75000.For estimation of nanofluid flow behavior,two-phase mixture method is used.The second-order discretization and SIMPLEC algorithm are used for solving governing equations.The results indicate that the increase of volume fraction of nanoparticles leads to the enhancement of the temperature of central line of flow.The increase of Grashof number(Gr^75000)has a great effect on reduction of dimensionless temperature in central line of flow.Creation of thermal boundary layer at Re=500 and after the angle of 30°becomes significant.In low Grashof numbers(Gr^15000),due to the great effects of temperature gradients close to wall,these regions have significant entropy generation.

关键词： elliptical minichannel Mixed convection Numerical study Nanofluid Finite volume method Friction factor

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elliptical High-Order Harmonic Generation from H_(2)^(+) in Linearly Polarized Laser Fields

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Chinese Physics Letters 2013年第2期30卷 74-77页

作者：张斌赵增秀 Department of Physics National University of Defense TechnologyChangsha 410073

We investigate the elliptical high-order harmonic generation(HHG)from the ground state of H_(2)^(+)subjected to linearly polarized laser fields,by numerically solving the three-dimensional(3D)time-dependent Schrödinger equation(TDSE)and using the strong-field approximation(SFA)models.Highly elliptical HHG is yielded at intermedial alignment angles from the TDSE,while the standard SFA model fails to predict this.By including the coulomb potential and the stark shift corrections,we yield qualitative agreement results with the TDSE.The comparisons show that in the description of elliptical HHG,both the coulomb potential and the stark-shift are necessary.

关键词： elliptical qualitative correction

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Formulization of Three-Dimensional Stress and Strain Fields at elliptical Holes in Finite Thickness Plates

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Acta Mechanica Solida Sinica 2019年第4期32卷 393-430页

作者： Wei Guo Wcinlin Guo State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016 China

Stress raisers such as holes are inevitable in structures at which stress concentration occurs and the static as well as fatigue strength of the structures can be significantly weakened. Therefore, to accurately evaluate the stress concentration factor and stress fields at holes is of essential importance for structure design and service life prediction. Although stress and strain concentration and fields at holes in finite thickness plates strongly change with and along the thickness, manuals of stress concentration for engineering design are mainly based on twodimensional theory and no explicit formula is available even for circular holes in finite thickness plates. Here we obtain for the first time a complete set of explicit formulae for stress and strain concentration factors and the out-of-plane constraint factor at circular as well as elliptical holes in finite thickness plates by integrating comprehensive three-dimensional finite element analyses and available theoretical solutions. The three-dimensional stress distributions ahead of holes can also be predicted by the obtained formulae. With their accuracy and the corresponding applicable range being analyzed and outlined in detail, the formulae can serve as an important fundamental solution for three-dimensional engineering structure design and guideline for developing threedimensional analytical methods.

关键词： Three-dimensional stress and strain concentration Stress field elliptical holes Finite thickness plate Explicit solution

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Comparing the behavior of orbits in different 3D dynamical models for elliptical galaxies

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Research in Astronomy and Astrophysics 2012年第4期12卷 383-399页

作者： Euaggelos E.Zotos Department of Physics Section of Astrophysics Astronomy and Mechanics Aristotle University of Thessaloniki 541 24 Thessaloniki Greece

We study the behavior of orbits in two different galactic dynamical models, describing the motion in the central parts of a triaxial elliptical galaxy with a dense nucleus. Numerical experiments show that both models display regular motion together with extended chaotic regions. A detailed investigation of the properties of motion is made for the 2D and 3D Hamiltonian systems, using a number of different dynamical parameters, such as the Poincare′ surface of a section, the maximal Lyapunov Characteristic Exponent, the S（c） spectrum, the S（w） spectrum and the P （f ） indicator. The numerical calculations suggest that the properties of motion in both potentials are very similar. Our results show that one may use different kinds of gravitational potentials in order to describe the motion in triaxial galaxies while obtaining quantitatively similar results.

关键词： galaxies kinematics and dynamics-- galaxies elliptical

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The asymptotic distributions of the statistics of the skew elliptical variables

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Science China Mathematics 2005年第2期48卷 214-221页

作者： FANG Biqi Institute of Applied Mathematics Academy of Mathematics and System SciencesChinese Academy of SciencesBeijing 100080China

In this paper, the asymptotic properties of the quadratic forms and the T statistic of the skew elliptical variables are studied. Consistent estimators of some parameters are obtained. The robustness of the significan... 详细信息

关键词： skew elliptical distribution, asymptotic distribution, consistent estimator, hypothesis testing.

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Elastic fields induced by non-elastic eigenstrains in a plane elliptical inhomogeneity existing in orthotropic media under uniform tension at infinity

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Science China(Physics,Mechanics & Astronomy) 2008年第2期51卷 206-218页

作者： GUO Lei NIE GuoHua Institute of Applied Mechanics School of Aerospace Engineering and Applied MechanicsTongji UniversityShanghai 200092China

This paper presents an analytical solution for the elastic fields induced by non-elastic eigenstrains in a plane elliptical inhomogeneity embedded in the orthotropic matrix under tension at infinity and inclined at any angle. The conformal transformation and complex function method for the anisotropic elastic material were used to determine the strain energies in the inhomogeneity and matrix, which were expressed by four undetermined coefficients characterizing the equilibrium boundary of the inhomogeneity due to the acting eigenstrains and external load. The use of the principle of the minimum potential energy led to analytical expres-sions for these coefficients and thus generated a closed-form solution for the elas-tic strain/stress fields. The resulting stress field in the inhomogeneity was exam-ined and verified by checking the continuity conditions for the normal and shear stresses on the interior boundary of the matrix.

关键词： complex function method conformal transformation orthotropic elliptical inhomogeneity tension non-ela-stic eigenstrains

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On some tests-based projection pursuit for elliptical symmetry of a high-dimensional distribution

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Chinese Science Bulletin 1998年第6期43卷 450-458页

作者： JING Ping 1 and ZHU Lixing 2 1. Mathematics Lab, China University of Mining & Technology, Beijing 100083, China 2. Probability Lab, Institute of Applied Mathematics, Chinese Academy of Sciences, Beijing 100080, China Mathematics Lab China University of Mining & Technology Beijing China Probability Lab Institute of Applied Mathematics Chinese Academy of Sciences Beijing China

Some test statistics of Kolmogorov type and Cramér-von Mises type based on projection pursuit technique are proposed for the testing problem of sphericity of a high-dimensional distribution. The limiting distributions of the test statistics are derived under the null hypothesis and under any fixed alternative. The asymptotic properties of bootstrap approximation are investigated. Furthermore, for computational reasons, an approximation for the statistics, based on the number theoretic method, is suggested.

关键词： bootstrap approximation projection pursuit type statistic elliptical symmetry.

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THE RESEARCH OF RESONANT CAVITY WITH elliptical CROSS-SECTION AT MODERATE ECCENTRICITY IN GYROTRON

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电子科学学刊(英文版) 1986年第3期3卷 167-172页

作者：蒋曼英祝西里李慧斌陆孝厚丁耀根 Department of Radio and Electronics Peking University Department of Radio and Electronics Peking University Institute of Electronics Academia Sinica

In this paper,the method of calculating cut-off frequencies of TE modes in elliptical waveguideis given.From the calculations,it is demonstrated that the gyrotron utilizing a cavity with ellipticalcross-section of moderate eccentricity has the following characteristics:(a)a large volume cavitycan be used;(b)the density of modes which can oscillate is low;(c)it is allowable to use an electronbeam with a large diameter;(d)it is possible to use a cavity mode with low azimuthal number.

关键词： elliptical utilizing calculating moderate waveguide slowly handling desired radial orders

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SOLITON AND elliptical PERIODIC SOLUTIONS TO THE MODIFIED NONLINEAR SCHRODINGER EQUATION

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Systems Science and Mathematical Sciences 1999年第3期12卷 263-269页

作者： LIU Xiqiang(Department of Mathematics, Liaocheng Teachers College, Shandong 252000, China) 聊城师范学院数学系山东聊城 252000

In this note, we have obtained the soliton and periodic solutions to the modifiednonlinear Schrodinger equation (MNLSE) and analysed the features of the soliton solutions.In particular, we point out that the nonlinear... 详细信息

关键词： Stronger equation solution elliptical periodic solution phase plane

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