Photoinduced optical activity of C<Subscript>70</Subscript> fullerene in organic solvents

We have experimentally studied for the first time the effect of photoinduced rotation of the plane of polarization for pulsed laser radiation in solutions of C₇₀ fullerene in organic solvents and their mixtures. We have shown that the effect is observed for elliptical polarization of the laser radiation and is absent for linear polarization. We present the results of a study of the nonlinear optical characteristics of the C₇₀ solutions. We discuss the physical mechanisms by which nonlinear gyrotropy is induced in solutions. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 93–99, January–February, 2009.     

一类非线性相对转动周期系统的平衡稳定性分析

利用一类周期性变系数线性常微分方程解的基本矩阵的Jordan形，分析一类非线性相对转动系统扭转的运动稳定性，从而得到非线性相对转动周期系统的运动稳定准则. 运用Lyapunov函数法，对广泛存在的一类机械传动系统的相对转动运动的平衡稳定位置的稳定域进行研究，并给出数学解析表达式. 这为工程中广泛存在的这类机械传动系统稳定工作区间工作参数的选取和相似模拟提供了理论依据及方法，据此可进一步分析和评价大型复杂旋转机械主传动系统的扭振稳定性. 关键词： 相对转动 相似模拟 运动稳定 平衡稳定     

EAST����������ע��ij���ʵ���о�

对EAST中性束反向注入过程中等离子体加热和电流驱动进行了实验研究,并采用了美国普林斯顿大学等离子体物理实验室开发的TRANSP程序对高功率中性束注入过程中能量热输运进行了分析.结果表明,中性束注入可有效提高本底等离子体温度,产生束驱动非感应电流,提高等离子体旋转以及有效改善等离子体约束.     

一类相对转动时滞非线性动力系统的稳定性分析

建立了具有时变刚度、非线性阻尼和谐波激励的一类相对转动时滞非线性动力系统的动力学方程.采用多尺度法推导出时滞动力系统的分岔响应方程,运用奇异性理论研究系统结构稳定性,得到主共振稳态响应方程的转迁集以及不同参数下分岔曲线的拓扑结构.应用Hopf分岔理论讨论了时滞动力系统动态稳定性,给出了系统产生极限环的条件,最后用数值模拟的方法研究了时滞参数对系统极限环幅值的影响。     

The application of laser reflective tomography in near-field measurements of ultrasonic transducers

With Laser Reflective Tomography（LRT）,the near fields of ultrasonic transducers were measured and analyzed.The principle of LRT measurement of ultrasonic field distribution was introduced and an experimental system was set up.Acoustic pressure of a multiple element piston transducer was measured by using of a laser vibrometer.Its distribution in amplitude and phase was obtained.The acoustic pressure in the same region was measured with a needle hydrophone to validate the LRT method.Furthermore,through reconstruction of acoustic fields,it indicated that LRT method is suitable for predicting the distribution on transducers＇surface and conditions of active elements.     

基于模场自积增强检测的光纤声光旋转传感器

介绍了一种应变不敏感的基于模场自积增强检测的光纤声光旋转传感器.通过调节加载到光纤声致光栅上的微波频率能使双模光纤输出高纯度LP_(11)模式.采用自积增强算法显著提高传感分辨比例,改善探测速度,实现对环境旋转角度变化的动态监测.传感器在0°—180°的测量范围内,角度最大测量误差范围小于11%;在轴向应变为100—1500με之间对应变不敏感.     

Structural studies on banana oil,isoamyl acetate,by means of microwave spectroscopy and quantum chemical calculations

The rotational spectrum of isoamyl acetate, H₃C–COO–(CH₂)₂–CH(CH₃)₂, has been recorded and assigned using a molecular beam Fourier transform microwave (MB-FTMW) spectrometer in the frequency range of 3–26.5?GHz. One conformer has been observed. By comparing the spectroscopic data with the quantum chemical data, it was found that the conformer observed does not have C_s symmetry. The rotational and centrifugal distortion constants were determined. The barrier to internal rotation of the acetate methyl group was found to be 93.98?cm^?1. Due to the high number of the conformers, a systematic nomenclature will be presented.     

偏振法测葡萄糖浓度的光强分析简

通过对旋光仪三分视场内的光强分析,对“零度视场”法和“三分视场明暗对比最大”的方法进行了详细的讨论。结果表明,采用“三分视场明暗对比最大”法在多数情况下更适合人眼感光定标,可以保证测量数据精度。“零度视场”法只在相位延迟角较小,三分视场由中间暗、两边亮变化到中间亮、两边暗过程中适用性较好。     

奇妙的惯性力

实际的参考系都不是惯性系，因此必须考虑惯性力．     

A theoretical and experimental study on all-normal-dispersion Yb-doped mode-locked fiber lasers

We report on a theoretical and experimental study of an all-normal-dispersion (ANDi) Yb-doped mode-locked fiber laser, in which nonlinear polarization rotation (NPR) is used to realize mode-locking without any dispersion compensation. Based on the coupled nonlinear Schrdinger (CNLS) equation, a model simulating the mode-locked process of an allnormal-dispersion ring fiber laser is developed, which shows that the achievement of stable mode-locking depends on the alignment of the polarization controller (PC) along the fast-polarization axis of the fiber, the birefringence intensity, and the net cavity dispersion. According to the theoretical analysis, stable mode-locked pulses with pulse duration 300 ps and average output power 33.9mW at repetition rate 36MHz are obtained.