Ultrafast high repetition rate absorption spectroscopy of polymer shock compression

A dual-beam transient absorption spectrometer for high repetition rate (80 shocks per second) studies of shock compressed materials is described. The apparatus time response is 100 ps, so the time resolution of the shock compression process is generally limited by the shock transit time across the sample. In turn the sample thickness is limited by the sensitivity of the spectrometer. Using 400 nm thick samples of R640 dye aggregates in \textit{poly} methyl methacrylate (PMMA) and a 4.2 GPa laser-driven shock, transient absorption spectra show a shock induced absorption redshift occurring in 500 ps, considerably longer than the 200 ps shock front transit time (round trip) through the sample. This noninstantaneous shock compression is consistent with the $\sim 300$ ps viscoelastic response of PMMA at 4.2 GPa. Received 30 July 2001 / Accepted 13 March 2002 – Published online 17 June 2002     

Contrast and sensitivity of the vibration fringes in time-averaged electronic speckle-pattern interferometry: effect of variations of force level

The time averaged frame subtraction technique is improved by subtracting two Bessel fringe patterns at two different force levels. The technique enables significant enhancement of fringe contrast and increased measurement sensitivity. The contrast and sensitivity of the fringes obtained at different force ratios are investigated. Both theoretical and experimental results are presented.     

基态和激发态氧振动光谱的量子力学计算

利用分子势能函数的Murrell-Sorbie和PG函数形式,将时域有限差分法应用基态和激发态氧分子的振动能级的量子力学计算,计算结果令人满意.     

三圆盘扭振系统主共振的理论与实验研究

本文应用非线性振动的平均法，分析了一个具有立方非线性并受简谐激励作用的三圆盘扭振系统的第二阶主共振，求得了稳态响应的分岔方程，并进行了奇异性分析，理论结果与实验结果相符·     

A Dynamic Frictional Contact Problem with Normal Damped Response

We consider a mathematical model which describes the frictional contact between a viscoelastic body and a reactive foundation. The process is assumed to be dynamic and the contact is modeled with a general normal damped response condition and a local friction law. We present a variational formulation of the problem and prove the existence and uniqueness of the weak solution, using results on evolution equations with monotone operators and a fixed point argument. We then introduce and study a fully discrete numerical approximation scheme of the variational problem, in terms of the velocity variable. The numerical scheme has a unique solution. We derive error estimates under additional regularity assumptions on the data and the solution.     

Low-frequency harmonic vibration analysis with temporal speckle pattern interferometry

In this paper, the time sequence phase method (TSPM) has been applied to measure the displacement caused by low-frequency vibration in temporal speckle pattern interferometry (TSPI). The principle is that by capturing the temporal speckle patterns related to the object vibration, the whole-field displacement responses (amplitude and phase) of the vibrating object can be calculated through scanning these fluctuations. Thus, quantitative measurement can be carried out using a conventional ESPI system without a camera synchronized to the object vibration or a phase shifting system. The elaboration on the method is given and experimental results are presented.     

弹簧耦合摆小振动的简正模与简正频率

将耦合摆弹簧作为弹性均匀杆，导出了对称简正模与反对称简正模的本征方程，给出各角频率值的近似式，并进行了讨论。     

Mechanical and dynamic aspects of voice production as related to voice therapy and phonosurgery

Laryngeal framework surgery can change the position and tensionof the vocal folds safely without direct surgical intervention in the vocal fold proper. Some 23 years of experience with phonosurgery have proved its usefulness in treating dysphonia related to unilateral vocal fold paralysis, vocal fold atrophy, and pitch-related dysphonias. Meanwhile, much information about the mechanism of voice production has been obtained through intraoperative findings of voice and fiberscopic examination of the larynx . Based on such knowledge together with information obtained through model experiments, the human vocal organ was reconsidered mainly from the mechanical view point, and the roles of voice therapy and singing pedagogy were discussed in relation to phonosurgery. The vocal organ may not be an ideal musical organ and is rather vulnerable, but its potential is enormous.     

Assessing the ability of chemical similarity measures to discriminate between active and inactive compounds

Summary A method for assessing the biological discriminating power of chemical similarity measures is presented. The main concern of this work was to develop an objective way of evaluating different similarity measures in terms of how well they distinguished between active and inactive compounds. In addition, we have explored the level of similarity required for optimal separation and commented on its implications for work in the field of chemical diversity studies. The results for one simple similarity measure showed that statistically significant separation could be achieved, and indicated a reasonable similarity value for future work.     

振动钻削微小孔中钻头寿命与振动参数的二次回归试验研究

本文采用正交组合设计的试验方法，对振动钻削微小孔加工中钻头寿命与轴向振动参数之间的非线性关系进行了二次回归试验，得到了最优回归方程。用回归方程给出的最佳振动参数钻孔，钻头寿命提高了９６．３％