Sound propagation and relaxation processes in the isotropic phase of cholesteryl miristate

The propagation and absorption of high-frequency sound in the isotropic phase of cholesteryl miristate is studied in a wide frequency range using the data of both Brillouin spectroscopy and acoustooptic measurements. The parameters of the relaxation process associated with the volume viscosity relaxation are calculated using the experimental data on the velocity and absorption of sound.     

微晶玻璃中的声传播

本文把悬浮液中的声学处理方法应用到微晶玻璃中,导出了微晶玻璃中声速和声衰减系数随结晶度变化的表达式,并通过实验进行了证实。     

Dielectric relaxation in aqueous solutions and suspensions

A method is proposed for measuring the relaxational dielectric losses of liquids at radio frequencies on a background of large conductivity losses. The absorption of the electromagnetic field energy is explained by structural relaxation, i.e., by the processes of formation and destruction of clusters.Translated from Isvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 81–85, February, 1975.     

Dielectric relaxation in aqueous solutions and suspensions I. Solutions and suspensions

The dielectric constants and dielectric loss factors of aqueous solutions and suspensions are measured as a function of the specific electrical conductivity, temperature, and electric field frequency. The dispersion of the dielectric constant and the dielectric loss factor in solutions is explained by the formation of a electric double layer at the electrodes and the redistribution of the electric field between the region adjoining the electrodes and the remaining volume of the measuring cell. An equivalent-circuit calculations for suspensions displays acceptable agreement with experiment.     

A model of laminar flames in droplet suspensions

A mathematical model of steady laminar flame propagation through a suspension of liquid droplets was proposed, and numerical calculations within the framework of this model were performed. The model is constructed based on one-dimensional differential equations of the theory of laminar flames in homogeneous gaseous mixtures in conjunction with the theory of droplet burning in uniform monodisperse suspensions. The chemical process was described using a multistage kinetic scheme. A comparison of model predictions with the available experimental data demonstrated satisfactory agreement.     

声在参数随距离变化的管道中的传播

本文对管道系统中声传播的一维理论作了推广。把管道系统看成由两种类型结构组成:一种是连续的管道结构,其中壁面声学参数、截面几何参数以及气体动力参数等可以沿管道随距离缓慢变化;另一种是突变的局部结构,在结构两侧的各种参数可以有不连续的跃变。文中从流体力学基本方程出发,在较普遍的情况下,对这两种类型结构作了分析研究,分别导出了反映其声传播特性的传递矩阵并作了讨论。     

Numerical simulation of particle-laden droplet evaporation with the Marangoni effect

The European Physical Journal Special Topics - A comprehensive numerical method for analysis of the evaporation of a particle-laden microdroplet is developed including the effects of heat and mass...     

Sound propagation in two-dimensional waveguide with circular wavefront

Sound propagation through a waveguide is generally modeled by the Webster horn equation which assumes a planar pressure wavefront. However, most of the sources are non-planar in nature. In this work, a 1-D model is derived for sound propagation through a 2-D waveguide with circular wavefront. The model is derived from the 2-D Helmholtz equation using the weighted residual method. The model assumes a uniform pressure across the angular coordinate at a given radial distance. A 2-D finite element model is used to validate the results for different waveguide geometries and it shows good agreement.     

Sound propagation in a street

The propagation of sound in a street has previously been treated almost exclusively by the use of ray-tracing techniques. As a result, the effects of scattering from objects and protrusions in the street have not been taken adequately into account. In this paper, the sound field is analysed in terms of its propagating modes. The use of this technique allows the effect of scattering to be calculated, assuming a rather simplified model of a scattering surface. Although a number of important assumptions are made, the predicted attenuations at points down a street are in good agreement with results obtained from model studies. These attenuation curves are also similar in form to ihose obtained in full-scale tests.     

Sound propagation in fluids and neutron spectra

Using a model kinetic equation the properties of very short wavelength sound modes in fluids are studied over a wide range of wavenumbers and densities. The main features, in particular propagation gaps at high densities, agree with those found in real fluids and molecular dynamics simulations.     

Sound propagation and energy relations in churches

The results of an acoustic survey carried out in a group of Italian churches differing in style, typology, and location were used in order to study how the acoustic energy varies inside this kind of space. The effect of different architectural elements on sound propagation was investigated by means of three-dimensional impulse responses measured using a B-format microphone with sweep signals. Side chapels, columns, and trussed roofs appeared to scatter the reflections, so that the purely diffuse exponential sound decay begins after a time interval which grows with the source-receiver distance and with the complexity of the church. The results of the measurements were then compared with predictions given by existing theoretical models to check their accuracy. In particular a model previously proposed by the authors for a specific type of Romanesque churches was further refined taking into account the new findings and making some simplifications. Its application to the wider sample of churches under analysis showed that strength, clarity, and center time can be predicted with reasonable accuracy.     

浅海周期起伏海底环境下的声传播

海底粗糙对水下声传播及水声探测等应用具有重要影响.利用黄海夏季典型海洋环境,分析了同时存在海底周期起伏和强温跃层条件下的声传播特性,结果表明:由于海底周期起伏的存在,对于低频(<1 kHz)、近程(10 km)的声信号,传播损失可增大5—30 d B.总结了声传播损失及脉冲到达结构随声源深度、海底起伏周期及起伏高度等因...     

复杂厂房噪声传播

本文导出一个工业厂房噪声传播数学模型.这模型适用于任意形状、任意边界条件和有任意障碍物的厂房.发展这个模型的目的是为了电厂噪声预测.电厂厂房噪声传播测量结果表明,模型有很高精度和对各类复杂厂房的适应性。     

Sound propagation in the North Sea

Results of an experimental study of shallow-water sound fields are presented. The experiment is carried out in the frequency range 112–3200 Hz on a 150-km-long propagation track. A comparative analysis of experimental and calculated data is performed. Estimates are obtained for the loss coefficient associated with sound attenuation in the bottom, as well as for the parameters of the bottom, which is modeled as a homogeneous liquid absorbing half-space. The vertical interference structure of the sound field formed at a frequency of 112 Hz in the vicinity of the source is considered.     

Sound propagation in soundproofing casement windows

Casement windows consisted of two wooden frames that can be opened and closed at various angles are widely used in developing countries with tropical climates. However, an annual increase in a number of motorcycles and automobiles and traffic noise level these countries have rendered these windows to be useless. In this paper, we present a model for manufacturing windows which are suitable for the developing tropical countries. These windows are capable of ventilating, regulating sunlight, protecting against coldness, and reducing traffic noise and fumes from motor vehicles. The ventilation and soundproofing unit hold an importance place in the design of the windows and are calculated using the wave equation and observations of higher-order mode waves. In order to maximize the soundproofing ability, the selection of size and placement of input and output openings in such a way that would minimize the effects of higher-order mode waves are considered in details.     

Sound propagation in railway line cuttings

Sound propagation in and around railway line cuttings is in many cases dominated by multiple reflections between train body and cutting wall or between the cutting walls. Typical situations were examined by a large number of scale model experiments. Based on these results a simple empirical calculation scheme was deduced to estimate sound fields in the surroundings of railway line cuttings. The basic idea is to compose the sound field from three parts: the direct sound from the wheels, first order specular reflections and a diffuse sound portion that is emitted from the upper edges of the train body. The scheme can easily be incorporated into existing railway noise models.