A node-to-surface linear complementarity problem approach for general three-dimensional contact analysis

Meccanica - Contact between two deformable bodies is a complex nonlinear problem especially when rigid-body motion and geometric errors of components are taken into consideration. In this paper, an...     

二维正弦离散映射的分岔和吸引子

由一个正弦映射和一个三次方映射通过非线性耦合,构成一个新的二维正弦离散映射. 基于此二维正弦离散映射得到系统的不动点以及相应的特征值,分析了系统的稳定性,研究了系统的复杂非线性动力学行为及其吸引子的演变过程. 研究结果表明：此二维正弦离散映射中存在复杂的对称性破缺分岔、Hopf分岔、倍周期分岔和周期振荡快慢效应等非线性物理现象. 进一步根据控制变量变化时系统的分岔图、Lyapunov指数图和相轨迹图分析了系统的分岔模式共存、快慢周期振荡及其吸引子的演变过程,通过数值仿真验证了理论分析的正确性. 关键词： 正弦离散映射 对称性破缺分岔 Hopf分岔 吸引子     

塞曼效应与边缘离子温度的光谱测量

通过理论推导得到了谱线实际宽度和塞曼展宽之间的关系。在磁感应强度分别为1、2、2．5和3T的情况下，用数值方法进行了求解，用得到的结果拟合出了校正因子随离子温度变化的经验公式和拟合曲线，结果表明：离子温度较低时，塞曼效应对谱线宽度的影响很大，温度较高时，塞曼效应对谱线宽度的影响可以忽略。     

Ti-Zr-Ni单相准晶合金的室温力学性能研究

以Ti40₄₀Zr40₄₀Ni20₂₀合金为研究对象，用铜 模吸铸法制备出直径为3mm的致密单相准晶棒，通过维氏显微硬度测定和单向压缩实验方 法研究了该合金的室温力学性能 .结果表明：Ti40₄₀Zr40₄₀Ni20₂₀准晶具有良好 的弹性变形能力，室温弹性应 变可达125%.同时，它具有相对高的室温硬度（约55GPa），是普通Ti合金的15倍.T i40_{40 关键词： 准晶 Ti-Zr-Ni合金 解理断裂}     

Dispersion relation of charge gap excitations in quasi-1D Mott insulators studied by resonant X-ray scattering

Momentum dependence of charge excitations across the effective Mott gap in several quasi-low-dimensional model cuprates with different effective dimensionalities is studied using high resolution inelastic X-ray scattering by working near Copper k-edge resonance which allows us to extract the dispersion relations of the particle-hole pair excitations at the gap edge. Besides electron-electron correlation, momentum dependence of the gap-excitations is found to be strongly dependent on the effective dimensionality (or topology) of the 3dx²−y² network.     

Synthesis and properties of chitosan‐based thermo‐ and pH‐responsive nanoparticles and application in drug release

In this research, thermo‐ and pH‐responsive nanoparticles with an average diameter of about 50–200 nm were synthesized via the surfactant‐free emulsion polymerization. The thermal/pH dual responsive properties of these nanoparticles were designed by the addition of a pH sensitive monomer, acrylic acid (AA), to be copolymerized with N‐isopropylacrylamide (NIPAAm) in a chitosan (CS) solution. The molar ratio of CS/AA/NIPAAm in the feed was changed to investigate its effect on structure, morphology, thermal‐ and pH‐responsive properties of the nanoparticles. It was found that CS‐PAA‐PNIPAAm nanoparticles could be well dispersed in the aqueous solution and carried positive charges on the surface. The addition of thermal‐sensitive NIPAAm monomer affected the polymerization mechanism and interactions between CS and AA. The particle size of the nanoparticles was found to be varied with the composition of NIPAAm monomer in the feed. The synthesized nanoparticles exhibited stimuli‐responsive properties, and their mean diameter thus could be manipulated by changing pH value and temperature of the environment. The nanoparticles showed a continuous release of the encapsulated doxycycline hyclate up to 10 days during an in vitro release experiment. The environmentally responsive nanoparticles are expected to be used in many fields such as drug delivery system. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2798–2810, 2009     

A comparison of the performance of LiNbO3, and LiTaO3, traveling-wave phase modulators

A comparison of the phase modulators made by Ti:LiNbO₃ and Ti:LiTaO₃ optical waveguides is presented. Of particular interest is their halfwave voltages at the wavelength 0.6328 μm and the frequency responses for the same electrode structure. For the Ti:LiNbO₃ phase modulator, a halfwave voltage of 6.6 V and a band-width of 13 GHz are obtained. Whereas, the Ti:LiTaO₃, a 6.8 V halfwave voltage and 12 GHz bandwidth are obtained.