低温大试样热胀系数测试

本介绍了用熔融石英引伸法测量硬质材料热胀系数的简便装置,并给出了试样在液氦温区到室温的测量结果,数据的一致性以及与已有献数据比较取得了不错的结果．     

Colorimetric and electrochemical Pb~(2+) detection by imine-bridged tetrathiafulvalene-pyridine derivatives

Imine-bridged TTF-π-pyridine derivatives, 2NTTF, 3NTTF and 4NTTF, were synthesized and the cation-binding study was performed. It is noted that with the addition of the micromolar concentration of Pb2+ to the solution, these compounds display remarkable changes in solution color, 1H NMR spectra and electrochemical properties. The nitrogen atom of the imine-bridge in 2NTTF not only serves as a π-conjugated spacer but also participates in the sensing and coordinating properties.     

Facile aqueous synthesis and thermal insulating properties of low-density glass/TiO2 core/shell composite hollow spheres

Anatase TiO2 shells assembled on hollow glass microspheres(HGM)with tunable morphologies were successfully prepared through a controllable chemical precipitation method with urea as the precipitator. Thus,glass/TiO2 core/shell composite hollow spheres with low particle density(0.40 g/cm3)were fabricated.The phase structures,morphologies,particle sizes,shell thicknesses,and chemical compositions of the composite microspheres were characterized by X-ray diffraction(XRD),scanning electron microscopy (SEM),and energy dispersive X-ray spectroscopy(EDS).The morphology of the TiO2 shell can be tailored by properly monitoring the reaction system component and parameters.The probable growth mechanism and fabrication process of the core/shell products involving the nucleation and oriented growth of TiO2 nanocrystals on hollow glass microspheres was proposed.A low infrared radiation study revealed that the radiation properties of the products are greatly influenced by the unique product shell structures. A thermal conductivity study showed that the TiO2/HGM possess low thermal conductivity that is similar to that of the pristine HGMs.This work provides an additional strategy to prepare low-density thermal insulating particles with tailored morphologies and properties.     

激光光束传输因子M~2的一些问题

本文讨论与 M2 因子有关的一些问题 ,指出在近轴近似条件下由光束的二阶强度矩定义的 M2 因子满足 M2 ≥ 1 ,其中只有对基模高斯光束等式才成立 .由光束的功率通量值定义的 M2 因子 ( M2pc)有可能小于 1 ,M2pc的大小取决于所定义的光斑半径内包含的光功率的百分数 .通过计算光场的二阶矩 ,我们获得了轴向相干叠加的高斯光束的 M2 因子的解析解     

An automatic constraint violation stabilization method for differential/ algebraic equations of motion in multibody system dynamics

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｄｙｎａｍｉｃｅｑｕａｔｉｏｎｓｏｆｍｏｔｉｏｎｏｆｍｕｌｔｉｂｏｄｙｓｙｓｔｅｍｓｗｉｔｈｃｏｎｓｔｒａｉｎｔｓａｒｅｔｈｅｆｏｌｌｏｗｉｎｇｄｉｆｆｅｒｅｎｔｉａｌ／ａｌｇｅｂｒａｉｃｅｑｕａｔｉｏｎｓ,ｉ．ｅ．,Ｅ...     

Thermoelastic free vibration of clampe circular plate

An analysis was given for the free vibration of clamped circular plate when temperature and stress fields were coupled. A nonlinear differential equation about time was obtained by using Galerkin’s method. The numerical results of vibration amplitude vs time were compared with the uncoupled case. It is found that if the given initial displacement is small, the effect of thermoelastical coupling will make the natural frequency increase; if the given initial displacement is large, it will be the opposite case. Effects of some different vibration factors are also discussed.     

ON THE CRITICAL POINTS OF THE MAP Fp:X→‖AXB-C‖pp

Suppose A,B and C are the bounded linear operators on a Hilbert space H, when A has a generalized inverse A^- such that (AA^-)^*=AA^- and B has a generalized inverse B^- such that (B^-B)^*=B^-B,the general characteristic forms for the critical points of the map F_p:X^→‖AXB-C‖_p^p(1p=2. Similarly, the same question has been discussed for several operators.     

Periodic boundary value problems for first-order integro-differential equations of mixed type

ＩｎｔｒｏｄｕｃｔｉｏｎＣｏｎｓｉｄｅｒｔｈｅｆｏｌｌｏｗｉｎｇｐｅｒｉｏｄｉｃｂｏｕｎｄａｒｙｖａｌｕｅｐｒｏｂｌｅｍ(ＰＢＶＰ,ｆｏｒｓｈｏｒｔ)ｆｏｒｆｉｒｓｔ＿ｏｒｄｅｒｉｎｔｅｇｒｏ＿ｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｏｆｍｉｘｅｄｔｙｐｅｕ′=ｆ(ｔ,ｕ,Ｔ1ｕ,Ｔ2ｕ)　　(ａ.ｅ.ｔ∈Ｉ),(1)ｕ(0)=ｕ(2π),(2)ｗｈｅｒｅＩ=[0,2π],ｆｓａｔｉｓｆｉｅｓＣａｒａｔｈｅｏｄｏｒｙ’ｓｃｏｎｄｉｔｉｏｎｓ,Ｔ1ｉｓａＶｏｌｔｅｒｒａｉｎｔｅｇｒａｌｏｐｅｒａｔｏｒ,Ｔ2ｉｓａＦｒｅｄｈｏｌｍｉｎｔｅ…     

The finite element method based on interpolating with wavelet basis function

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｐｒｏｂｌｅｍｓｗｉｔｈｌａｒｇｅｇｒａｄｉｅｎｔａｒｅｃｏｍｍｏｎｉｎｐｒａｃｔｉｃａｌｅｎｇｉｎｅｅｒｉｎｇｆｉｅｌｄｓ,ｅ．ｇ．ｉｎｍａｔｅｒｉａｌｌｏｃａｌｉｚａｔｉｏｎ,ｗｉｔｈｉｎｔｈｅｌｏｃａｌｉｚａｔｉｏ...     

Linearized inverse scattering for elastic parameters in a half-space with reflection data

ＩｎｔｒｏｄｕｃｔｉｏｎＭｕｌｔｉｐａｒａｍｅｔｅｒｉｎｖｅｒｓｅｓｃａｔｔｅｒｉｎｇｆｏｒｅｌａｓｔｉｃｍｅｄｉｕｍｉｓａｆｏｕｎｄａｔｉｏｎａｌｐｒｏｂｌｅｍｉｎｓｅｉｓｍｏｌｏｇｙａｎｄｎｏｎｄｅｓｔｒｕｃｔｉｖｅｔｅｓｔｉｎｇ .ＷｉｔｈｉｎｔｈｅＢｏｒｎａｐｐｒｏｘｉｍａｔｉｏｎ ,ｔｈｉｓｐｒｏｂｌｅｍｈａｓｂｅｅｎｉｎｖｅｓｔｉｇａｔｅｄｂｙｓｅｖｅｒａｌａｕｔｈｏｒｓ.Ｂｌａｃｋｌｅｄｇｅｅｔａｌ.[1]ｈａｖｅｅｘｔｅｎｄｅｄｔｈｅＸ＿ｒａｙｔｏｍｏｇｒａｐｈｙｓｃｈｅｍｅｔｏｔｈｅｄ…