客车车身骨架动应力研究的现状与未来

综述了多体系统动态模型的发展及动态应力历程求解的进展,给出了国际上的最新研究成果,并以CJ6121GCHK型客车车骨架为例,给出了计算其动应力历程的步骤。     

Influence of Mg/Er co‐doping on the principal laser parameters of LiNbO3 crystals

Mg: Er: LiNbO₃ crystals were grown by the Czochralski technique with various concentrations of MgO = 2 mol%, 4 mol%, 6 mol% and the fixed concentration of Er₂O₃= 1 mol% in the melt, and the 8 mol%Mg: 1 mol%Er: LiNbO₃ crystal was fabricated by the Czochralski technique with special technology process. The crystals were treated by polarization, reduction and oxidation. The segregation coefficients of Mg²⁺ and Er³⁺ in Mg: Er: LiNbO₃ crystals were measured by X‐ray fluorescence spectrograph, as well as the crystal's defect structure and optical properties were analyzed by the UV‐Vis, IR and fluorescent spectroscopy. The pump wavelength and the surge wavelength were determined. Using m‐line method tested optical damage resistance of those crystals, the results show that photodamage threshold of Mg: Er: LiNbO₃ crystals are higher than that of Er: LiNbO₃ crystal, and the oxidation treat could enhance the photodamage resistant ability of crystals while the reduction treat could depress the ability. The optical damage resistance of 8 mol%Mg: 1 mol%Er: LiNbO₃ crystal was the strongest among the samples, which was two orders magnitude higher than that of 1 mol%Er: LiNbO₃ crystal. The dependence of the optical properties on defect structure of Mg: Er: LiNbO₃ crystals was discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synchronization between two different chaotic systems with nonlinear feedback control

This paper presents chaos synchronization between two different chaotic systems by using a nonlinear controller, in which the nonlinear functions of the system are used as a nonlinear feedback term. The feedback controller is designed on the basis of stability theory, and the area of feedback gain is determined. The artificial simulation results show that this control method is commendably effective and feasible.     

THE APPLICATION OF A NOVEL ADSORBENT IN RAPID SAMPLE CLEAN-UP OF GINKGOLIDES AND BILOBALIDE IN EXTRACTS OF GINKGO BILOBA LEAVES

1 INTRODUCTIONGinkgolides, known as specific antagonist of platelet factor (PAF), possess uniquepharmaceutical properties and are main active constituent of many phytopharrnaceuticpreparations based on ginkgo bilioba leaves extracts II]. Another active terpenoid, namelybilobalide, is reported recently to show potent therapeutic efficacy to the disease related to nervesystem 121. They are all terpene lactones, which are highly oxidized as illustrated in Figure 1.The first attempts to ana…     

‘Ligand-free’ palladium-catalyzed direct C–H bond oxidative acyloxylation of 2-arylpyridines with aromatic carboxylic acids

A palladium-catalyzed direct C–H bond oxidative acyloxylation of 2-arylpyridines with aromatic carboxylic acids is described. Several 2-arylpyridines derivatives and aromatic carboxylic acids participate in the reaction, providing a series of mono-acyloxylated products in moderate to good yields. Importantly, the reaction can be conducted without using any ligands in a lower temperature.     

Interference patterns of two non-diffracting beams

The interference field of two non-diffracting beams is derived analytically. We arrange the experiments with an axicon illuminated by two monochromatic oblique beams. Based on the diffraction properties of an axicon in the case of oblique illumination, the intensity distribution of interference pattern was calculated, and it was demonstrated to be the superposition of zero-order Bessel functions. The locus of interference fringes is also analyzed to be hyperbola according to the zero formula of zero-order Bessel function. The experimental results are verified the numerical simulation.     

Multimode resonance bandpass filter with twin wideband channels

A bandpass filter with twin wideband channels in a single-layer guided-mode resonance grating is presented.Strong refractive-index modulation is used to support the excitation of multimode resonances TE1,0,TE1,1,TE2,0,TE1,2,and TE2,1,which are excited by the first and second diffraction orders,relate asymmetrical line shapes and broad low-transmission bands,where TE is the transverse electric.Taking advantage of narrow linewidth and sharp edge line shape in the spectra of TE2,υ(v is the mode),a bandpass filter with form factors of 0.61 and 0.7 for long-and short-wave channels is presented to demonstrate this concept.