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Large second-order optical nonlinearities of s-triazine derivatives: View from micro molecules to macro crystals

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science china Chemistry 2005年第3期48卷 203-209页

作者： FANG Qi1, LEI Hong2. CUI Yuezhi3. HUANG Zhenli4, XUE Gang1 & YU Wentao1 1. State Key Laboratory of Crystal Materials, Shandong university, Jinan 2.0100, {3. 2. School of Information {2. and Engineering, Shandong university, Jinan 2.0100, {3. 3. department of Chemical Engineering, Light Industry College of Shandong, Jinan 2.0100, {3. 4. Key Laboratory of Biomedical Photonics, Ministry of Education, huazhong university of science and technology, Wuhan {13., {3. State Key Laboratory of Crystal Materials Shandong University Jinan China School of Information science and Engineering Shandong University Jinan China department of Chemical Engineering Light Industry College of Shandong Jinan China Key Laboratory of Biomedical Photonics Ministry of Education Huazhong University of Science and Technology Wuhan China

Three s-triazine derivatives have been synthesized and their structures been de-termined. These are Compound I: 2.4-dimethyl-6-(p-N,N-dimethylaminostyryl)-s-triazine (abbre-viated to NMe-1), Compound II: 2.4-dimethyl-6-(p-N,N-diethylaminostyryl)-s-triazine (to NEt-1), and Compound III: 2.methyl-4,6-bis(p-N,N-dimethylaminostyryl)-s-triazine (NMe-2.. NMe-1 and NEt-1 molecules belong to the D-π-A type with a one-dimensional charge-transfer character. NMe-1 crystallizes to centrosymmetric P1 space group, while NEt-1 to non-centrosymmetric polar Cc space group with all of the molecular charge-transfer axes taking the same orientation. Under the irradiation of 1064 nm fundamental laser, NEt-1 powder crystals radiate a 2.order harmonic light with an intensity 46.8 times that of urea. The Λ typed NMe-2.molecule, which has a two-dimensional charge-transfer character, crystallizes to polar P2. space group. Its powder crystals exhibit a 2.order harmonic intensity 46.2.times that of urea. The quantum chemical cal-culations and tensor analyses have been carried out to reveal the dependence of the macro 2.order nonlinear optical (NLO) efficiency on the micro 2.order NLO coefficients (β) and on the crystalline packing styles.

关键词： s-triazine derivatives, synthesis, structure, SHG intensities of crystals, βvalues of molecules.

Electrical Measurement to Assess Hydration Process and the Porosity Formation

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Journal of Wuhan university of technology(Materials {2.) 2008年第5期23卷 761-766页

作者：魏小胜 department of Civil Engineering Huazhong University of Science and Technology

The change of electrical resistivity with time at early ages was used to investigate the hydration process and the porosity development. Porosity reduction process of cement-based materials hydration was developed by a proposed method. The porosity reduction is fast at the setting period. The results find that the pore discontinuity occurs faster at lower water/cement ratios than at higher water/cement ratios which is similar to the results of the Percolation method.

关键词： electrical resistivity hydration setting time percolation

Numerical simulation of two-dimensional interface breakup

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Progress in Natural science:Materials International 2006年第5期16卷 554-558页

作者： CAI Yong,MA Dongjun, SUN Dejun and YIN Xieyuan (department of Modern mechanics, {2. of {3. and technology of china, Hefei 2.002., china) department of Modern mechanics University of Science and Technology of China Hefei 230027 China

The nonlinear evolution of the two-dimensional mixing layer flow of two immiscible fluids separated by the interface with surface tension is simulated numerically. The volume of the fluid method is used to capture the motion of the interface. A parametric study is conducted to investigate the effects of Weber number, Reynolds number, and the density ratio, etc. on the breaking process.

关键词： interface surface tension volume of fluid

A MODEL FOR CONCRETE DURABILITY DEGRADATION IN FREEZE-THAWING CYCLES

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Acta Mechanica Solida Sinica 2003年第4期16卷 353-358页

作者： Wei Jtm Wu Xinghao Zhao Xiaolong (School of Civil Engineering and mechanics,huazhong university of science and technology,Wuhan {2.,{3.) Sch. of Civ. Eng. and mechanics Huazhong Univ. of Sci./Technology Wuhan 430074 China

Up to now,how to control the durability of concrete structures is still a pending research topic in civil *** to the fact that concrete durability can be affected by many non-mechanical factors,it is very difficult to research durability only based on mechanics. However,the phenomenon of failure caused by non-mechanical factors is similar to that caused by *** frost durability reflects the comprehensive durability of concrete in a certain sense, the specific failure process is analyzed and a damage model is introduced,which can describe the durability degradation process of concrete in the whole freeze-thawing cycle.

关键词： concrete durability damage frost durability

Applications of semigroups of operators to non-elliptic differential operators

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Chinese science Bulletin 2000年第8期45卷 673-682页

作者： ZHENG Quandepartment of Mathematics, huazhong university of science and technology, Wuhan {2., {3. department of Mathematics Huazhong University of Science and Technology Wuhan China

This paper treats systematically the semigroup method of non-elliptic differential operators, which was developed in the last ten years. In particular, a review of the applications of regularized semigroups to non-elliptic differential operators with constant coefficients or time-dependent coefficients, parabolic systems, correct systems, abstract differential operators and pseudodifferential operators is given here. It is also shown that the regularized semigroup is an appropriate tool for non-elliptic differential operators and is far superior to the integrated semigroup approach.

关键词： differential operator regularized semigroup integrated semigroup initial value problem Fourier multiplier.

Synchrotron Radiation Tomography for Reconstruction of Layer Structures and Internal Defects of Composite Materials

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Chinese Journal of Lasers 1999年第6期8卷 24-29页

作者： LI Xide (department of Engineering mechanics, Tsinghua {2., Beijing 100084, {3.)HU Xiaofang (department of Modern mechanics and Engineering, {2. of science and technology of {3., Hefei 2.002., {3.) HU Yiguan KAN Ya (National Sy 清华大学工程力学系北京 100084 中国科学技术大学近代力学与工程系安徽合肥 230026 中国科学技术大学同步辐射国家实验室安徽合肥 230026 中国科学技术大学同步辐射国家实验室安徽合肥

Synchrotron radiation tomography has been used as a non intrusive technique to study layer structures and internal defects of composite materials with carbon aluminum fibers and boron carbon fibers. A rotatable platform, which is positioned in a vacuum chamber of a beam line, is used to hold specimens and to get multi directional scanning images. The scanning images are recorded on a PMMA film firstly by use of the single exposure method, resampled by a microscopic system, and reconstructed with computerized tomography to yield their three dimensional descriptions. This reconstruction makes it possible to identify different layers and structures of composite materials. Particularly the defects inside composite materials can also be detected and evaluated.

关键词： composite material synchrotron radiation computerized tomography reconstruction nondestructive evaluation

1/2.SUBHARMONIC RESONANCE OF A SHAFT WITH UNSYMMETRICAL STIFFNESS

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Chinese Journal of Mechanical Engineering 2003年第1期16卷 25-27,30页

作者： Xiao XiwuYang Shuzi Huang Yuyingdepartment of mechanics,{2. {3. of scienceand technology,Wuhan 43.074, china department of mechanics Huzahong University of Scienceand Technology Wuhan 430074

The 1/2.subharmonic resonance of a shaft with unsymmetrical stiffness is studied. By means of the Hamilton's principle the nonlinear differential equations of motion of the rotating shaft are derived in the rotating rectangular coordinate system. Transforming the equations of motion from rotating coordinate system into stationary coordinate system and introducing a complex variable, the equation of motion in complex variable form is obtained, in which the stiffness coefficient varies periodically with time. It presents a nonlinear oscillation system under parametric excitation. By applying the method of multiple scales (MMS) the averaged equation, the bifurcating response equations and local bifurcating set are obtained. Via the theory of singularity, the stability of constant solutions is analyzed and bifurcating response curves are obtained. This study shows that the rotating shaft has rich bifurcation phenomena.

关键词： Shaft with unsymmetrical stiffiless Subharmonic resonance Stability Bifurcation MMS

A NOTE ON THE DIPERNA-LIONS FLOWS

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Acta Mathematica Scientia 2011年第5期31卷 1719-1724页

作者：刘昕黄文亮 School of Computer science and technology Huazhong University of Science and Technology department of Mathematics East China University of Science and Technology

In this note, we give a short proof for the DiPerna-Lions flows associated to ODEs following the method of Crippa and De Lellis [3.. More precisely, assume that [divb] ∈ Ll∞oc（Rd）, ｜b｜/（1 ＋｜x｜ log ｜x｜） ∈ L∞（Rd） and ｜ b｜ φ（｜ b｜） ∈ Ll1oc（Rd）, where φ（r） = log log（r ＋ c）, c 0. Then, there exists a unique regular Lagrangian flow associated with the ODE X˙（t, x） = b（X（t, x））, X（0, x） = x.

关键词： DiPerna-Lions flow Hardy-Littlewood maximal function

THE CHARACTERISTICS OF LASER GENERATED ULTRASOUND IN SOLIDS

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Acta Mechanica Solida Sinica 1997年第3期10卷 189-197页

作者： Wu Yaping He Yulong Shi Dufang, department of Physics, huazhong university of science and technology, Wuhan {2., {3. department of Physics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

The laser generated ultrasound in solids in a thermoelastic regime is studied by solving thermoelastic wave equations. Analytic expressions of two-dimensional far-field ultrasonic displacements including the effects of thermal diffusion and optical penetration were obtained by means of the integral transform method. The meaning of the expressions is discussed. The effects of optical absorption coefficient on the directivity of laser generated ultrasound in non-metallic solids are also discussed. The directivity patterns of both longitudinal waves and shear waves are presented.

关键词： laser generated ultrasound the effect of thermal diffusion the effect of optical penetration directivity relative depth of optical penetration