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41.
云天铨 《应用数学和力学(英文版)》1985,6(1):53-59
According to a lemma and an assumption, this paper prexenis formulae of force at a point in the interior of a half space with Poisson’s ratio v = constant and shear modulus G linearly varied with depth. These formulae can be used as an approximate basic solution when the integral equation method is employed for the analysis of piles and other geotechnical engineering problems. 相似文献
42.
Ferroelectric phase transition in RbH2PO4 has been investigated using propagation of longitudinal acoustic waves along the polar axis near the transition temperature.
The velocity of this mode is continuous across the transition temperature. Velocity data in the ferroelectric phase are analyzed
in terms of coupled soft modeacoustic mode model of Pytte to obtain the temperature dependence of the soft mode frequency.
The attenuation data in the ferroelectric phase show power law dependence. It follows scaling behaviour of the type predicted
by Kawasaki from the mode-mode coupling theory and the dynamical scaling. 相似文献
43.
Denis J. Evans 《Journal of statistical physics》1979,20(5):547-555
Nonequilibrium molecular dynamics calculations are used to show that polyatomic fluids can support antisymmetric stress. In a homogeneous system where the time dependence of vorticity is a step function, it is shown that the rate at which intrinsic angular velocity approaches its steady-state value ( = 1/2 × u) is determined by the magnitude of the antisymmetric part of the pressure tensor. 相似文献
44.
45.
本文对垂直低温两相流管底部液氮汽泡的上升速度运用高速摄像机进行了可视化实验研究,对所采集的实时图像进行处理.在Cole和Mendelson汽泡上升速度经验公式的基础上,通过对液氮汽泡的上升速度的分析,提出了圆管管路底部液氮汽泡的上升速度的拟合公式,分析研究其变化规律,为进一步探求圆管内液氮弹状汽泡的生成机理提供依据. 相似文献
46.
SUMMARY: In recent years, the multiparametric approach for evaluating perceptual rating of voice quality has been advocated. This study evaluates the accuracy of predicting perceived overall severity of voice quality with a minimal set of aerodynamic, voice range profile (phonetogram), and acoustic perturbation measures. One hundred and twelve dysphonic persons (93 women and 19 men) with laryngeal pathologies and 41 normal controls (35 women and six men) with normal voices participated in this study. Perceptual severity judgement was carried out by four listeners rating the G (overall grade) parameter of the GRBAS scale. The minimal set of instrumental measures was selected based on the ability of the measure to discriminate between dysphonic and normal voices, and to attain at least a moderate correlation with perceived overall severity. Results indicated that perceived overall severity was best described by maximum phonation time of sustained /a/, peak intraoral pressure of the consonant-vowel /pi/ strings production, voice range profile area, and acoustic jitter. Direct-entry discriminant function analysis revealed that these four voice measures in combination correctly predicted 67.3% of perceived overall severity levels. 相似文献
47.
Europium (Eu+) ions were confined in a Paul trap and detected by non-destructive method. Storage time of Eu+ ions achieved in vacuum was improved by orders of magnitude employing buffer gas cooling. The experimentally detected signal
was fitted to the ion response signal and the total number of ions trapped was estimated. It is found that the peak signal
amplitude as well as the product of FWHM and the peak signal amplitude is proportional to the total number of trapped ions.
The trapped ion secular frequency was swept at different rates and its effect on the absorption line profile was studied both
experimentally and theoretically. 相似文献
48.
We present a nondestructive technique to predict the refractive index profiles of isotropic planar waveguides, on which a thin gold film is deposited to as the cladding. The negative dielectric constant of the metal results in significant differences of effective indices between TE and TM modes. The two polarized modes and a surface plasmon resonance (SPR) with abundant information of the surface index can be used to construct the refractive index profiles of single-mode and two-mode waveguides at a fixed wavelength. 相似文献
49.
介绍了一套用于机载平台测量的非相干宽带腔增强吸收光谱(IBBCEAS)系统,并应用于实际大气NO_2空间分布的高时间分辨率观测.为满足机载测量中对时间分辨率的需求,系统采用离轴抛物面镜代替消色差透镜提高光学耦合效率;并运用Allan方差,对系统性能进行了分析.通过腔增强吸收光谱系统与长光程吸收光谱系统对实际大气NO_2的对比测试,两者线性相关系数R~2达到0.86.将IBBCEAS系统应用于机载平台,在时间分辨率为2 s的情况下,探测限达到95 ppt(1σ).通过机载观测,获得了华北地区石家庄等地上空对流层大气NO_2的廓线信息. 相似文献
50.
Bindiya Chana 《Journal of Macromolecular Science: Physics》2017,56(11-12):863-872
The optical, electrical and acoustical properties of polymer solutions based on polyvinyl pyrrolidone (PVP) doped with cupric sulphate (CuSO4) were studied. The polymer solutions were prepared by varying the concentration of Cu in the PVP using a simple chemical route. The UV-visible spectroscopy results showed that the optical absorbance decreased with an increase in wavelength from 300 to 700 nm. The optical band gaps were found to decrease with addition of the Cu salt in the polymer. The refractive index also showed significant variation with the doping of the CuSO4. The electrical conductivity of the polymer solutions was found to increase with temperature as well as concentration of Cu while the activation energy of electrical conduction decreased with concentration of Cu. The ultrasonic velocities of the polymer solutions were measured at a frequency of 1 MHz using an ultrasonic interferometer. The ultrasonic velocity and surface tension were increased while the adiabatic compressibility, acoustic impedance and intermolecular free length, the average distance between the surfaces of the coils of adjacent molecules, were decreased with increase in the concentration of CuSO4 in the PVP. 相似文献