Simple and efficient synthesis of 3-aminopropenones and 3-aminopropenoates catalyzed by copper(II) nitrate trihydrate under solvent-free conditions

A simple, efficient and environmentally begin method has been developed for the synthesis of 3-aminopropenones and 3-aminopropenoates through the reaction of 1,3-dicarbonyl compounds with amines in the presence of Cu(NO₃)₂ · 3H₂O under solvent-free conditions. Correspondence: Geng-Chen Li, School of Material Science and Engineering, Shijiazhuang Railway Institute, Shijiazhuang 050043, China.     

Evolutions of morphology and crystalline ordering upon annealing of quenched isotactic polypropylene

Quenched mesomorphic isotactic polypropylene precursor material has been investigated as well as the material annealed at different temperatures. At room temperature, morphology and crystalline ordering of the materials have been studied by atomic force microscopy (AFM) and wide‐angle X‐ray diffraction (WAXD). The nodular morphology of the mesomorphic precursor remains constant for annealing temperatures T_a below 120 °C. Needle‐like or leaf‐like crystals form when T_a approaches the melting temperature of the precursor. WAXD data analyzed by peak‐fitting indicate that the crystalline ordering along both the chain axis and the lateral directions quickly develops during the mesomorphic‐to‐monoclinic transition, but slowly after the transition (T_a > 140 °C). Combining the AFM and WAXD results it is proposed that two decoupled structure evolution mechanisms are occurring. During the transition, only the crystalline ordering is increasing, but not the size of the nodules. After the transition, the geometry of the nodules changes considerably, whereas there is little additional increase of crystalline ordering. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1703–1712, 2009     

可修系统故障诊断的标准值研究

本文利用数理统计方法研究可修系统故障诊断问题，提出了一种新的标准值。     

THE SYMMETRY CONSTRAINT AND LEVY EVOLUTION EQUATION HIERARCHY

1IntroductionThesymmetryconstraintgivestheinterrelationbetweenhigher-dimensionalintegrablesystemsandlower-dimensionalintegrablesystemsandprovidesadirectmethodtoconstructsolutionsofhigher-dimensionalintegrablesystemsbysolvinglower-dimensionalintegrablesyst…     

Theoretical and experimental studies on the aerodynamic instability of a two-dimensional circular cylinder with a moving attachment

Rain–wind induced vibration of cables in cable-stayed bridges is a worldwide problem of great concern. The effect of the motion of water rivulets on the instability of stay cables has been recognized as one of the mechanisms of this complex phenomenon. In order to investigate how the motion of rivulets affects the unstable vibration of cables without considering the effects of axial flow and axial vortex, a real three-dimensional cable was modeled as a two-dimensional circular cylinder, around which an attachment representing the rivulet can move. This could also be regarded as a new kind of two-dimensional 2-dof dynamic system. This paper studies the aerodynamic instability of the system theoretically and experimentally. Equations governing the motions of the cylinder and the attachment are first established. The Lyapunov stability criterion is applied to the equations of motion to derive the criterion for the unstable balance angle of the attachment. Moreover, a new two-dimensional 2-dof cable model system with a movable attachment is designed and tested in a wind tunnel. Parametric studies are carried out to investigate the effects of major factors such as wind speed, frequency and damping of the dynamic system on the unstable balance angle of the rivulet attachment. Theoretical and experimental results match well. These results may be valuable in elucidating the mechanism of rain–wind induced vibration of stay cables.     

不同能量下核束缚能的影响

在不同能量下， 利用核束缚能对虚光子四动量的平方项进行修正， 分别计算了Sn核碰撞中核束缚能对反应截面中湮灭项和康普顿散射项及K因子的影响。 结果表明， 核束缚能在小x区域对反应截面中湮灭项和康普顿散射项及K因子的影响明显， 并且能量越低这种影响越显著， 随着x2增大影响逐渐消失。 We made a revision of square of virtual photon four momentum by means of using nuclear bin ding energy formula in different energy， and we also made an accurate calculation for the effect of nuclear binding energy on K factor and Compton term and annihilate term in the Drell Yan process of the Sn Sn collision. The outcome indicates that the effect of nuclear binding energy on the annihilate term and the Compton term is marked in little x region and the effect will become more obvious with decrease of the energy and come to disappear with increase of the x.     

Variation method for acoustic wave imaging of two dimensional targets

IntroductionAcousticwaveimaginghasagreatpotentialtobeappliedtonondestructivetesting ,medicalimaging ,geologicalprospectingandmaterialscienceetc.,andvariousimagingmethods,eachpossessingitsownpeculiarities,havebeenproposed .In 1 992 ,Moghaddam[1]putforwarda…     

偏压电场作用下磁电弹板中Lamb波传播研究

基于磁电弹性材料的本构关系和运动微分方程,研究了磁电弹板中Lamb波的传播特性.在电磁开路和短路两种边界条件下,导出了偏压电场作用下磁电弹板中Lamb波的对称模态和反对称模态的相速度方程,求解了相应的应力场.通过数值算例分析了偏压电场对相速度和应力场的影响.结果表明,偏压电场对相速度有较大影响,对应力场几乎没有影响.研究成果可为设计磁电换能器提供一定的理论参考.     

Two-mode squeezed state of nanomechanical resonators

In this paper, we introduce a flexible model for the control and measurement of NAMRs （nanomechanical resonators）. We obtain the free Hamiltonian of the dcSQUID （direct current superconducting quantum interference device） and the interaction Hamiltonian between these two NAMRs and the dc-SQUID by introducing the annihilation and creation operators under the rotating wave approximation. We can treat the mode of the dc-SQUID as a classical field. In the Heisenberg picture, the generation of two-mode squeezed states of two nanomechanical resonators is shown by their collective coordinate and momentum operators.     

Crack growth of an interface crack between two dissimilar magneto-electro-elastic materials under anti-plane mechanical and in-plane electric magnetic impact

This paper examines the dynamic response of an interface crack between two dissimilar magneto-electro-elastic materials subjected to the mechanical and electric magnetic impacts. The magneto-electric impermeable boundary conditions are adopted. Laplace and Fourier transforms and dislocation density functions are employed to reduce the mixed boundary value problem to Cauchy singular integral equations in Laplace transform domain, which are solved numerically. Lots of numerical results are given graphically in time domain. The effects of electric impact loading and magnetic impact loading on dynamic energy density factors are discussed. Crack growth and propagation is predicted. The study of this problem is expected to have applications to the investigation of dynamic fracture properties of magneto-electro-elastic materials with cracks.