Acoustic Impedance

Ultrasonic investigations of molecular interactions of polymer blends of chitosan (Ch)/ polyvinyl pyrrolidone (PVP), in a buffer solution (0.1 M acetic acid + 0.2 M sodium acetate) have been reported within the temperature range 303.15 K-323.15 K. Several acoustic parameters such as acoustic impedance, isothermal compressibility, adiabatic compressibility, internal pressure have been determined. Various thermo-dynamical parameters viz; pseudo-Gruneisen parameter and surface tension have been evaluated. Some thermo-elastic parameters such as bulk modulus, shear modulus and Young's modulus are also computed. The non-ideal behaviour of the blend, in the buffer solution has been explained in terms of its composition and temperature variation of acoustical and thermo-dynamical parameters. The reliability model for polymer blends of chitosan (Ch)/ polyvinyl pyrrolidone (PVP) has also been proposed.

In previous work on acoustical lens effect, a model based on the annular decomposition of an axisymmetric focused piezoelectric transducer was described and found to be in agreement with FEM and experimental results. The design of a focused transducer must take into account both radiation and transduction properties. These complex models such as FEM, FDTD and PSTD methods take into

An acoustic impedance inversion (AI) analysis has been carried out with an inversion-based model to identify reservoir rock (sandstone) on the Sahul platform, precisely at the Flamingo height. The Plover Formation is a formation containing gas sand interbedded with thin shale. Mistral 1 well log analysis was used to determine the value of the acoustic impedance of the sandstone. The results of log analysis on the Plover formation show that the reservoir of low impedance values is interpreted as sandstone 31000-37500 (ft/s) * (g/cc) while high impedance is interpreted as shale > 37500 (ft/s) * (g/cc). Time slice inversion of acoustic impedance shows that the sandstones of the Plover Formation are concentrated to the west of the Mistral 1 well, precisely in the Flamingo High structure of the Bayu Undan gas field at Timor Sea.

Ultrasonic velocities have been measured in Phosphoryl Chloride by Kaulgud et al. using a special technique as it is corrosive. Using these results we have studied the temperature dependence of Rao's constant, Wada's constant, acoustic impedance, pseudo-Gruneise4n parameter, effective Debye temperature, free length and Lagemann's relation. We have also studied the relation between ultrasonic velocity and latent heat of vaporization, suggested by B. Ramachandra Rao. The results indicate a strong molecular association in Phosphoryl chloride due to dipole-dipole interactions. The excess energy of association, over and above the Van der Waal's contribution, has a value comparable to the binding energy of potassium metal.

In this article various acoustical and thermodynamical parameters of sixteen fluorocarbon refrigerants, each at a particular temperature, are calculated using data available in the literature. The acoustical parameters like ultrasonic velocity, adiabatic compressibility, molar sound velocity, molar compressibility, acoustic impedance, molar sound volume, pseudo-Gruneisen parameter, and effective Debye temperature are studied. The thermodynamical parameters such as molar volume, free volume, available volume, surface tension, intermolecular free lengths, and relative association have also been calculated. Ultrasonic velocity values evaluated using intermolecular free length theory (FLT) and collision factor theory (CFT) and Auerbach relation are also compared and the results discussed in terms of the interactions present in the systems. The Rao-Padmini formulation is used to predict the excess energy of association per mole (over and above the Van der Waal's contribution). An attempt is made to arrange the refrigerants under study, in order of their efficiency to absorb or extract heat from the substances to be refrigerated.

An investigation in the ultrasound response of some binary mixtures of reciprocal salt pairs, I. CdCBr2 + KCl, II. CdCl2 + KBr, III. LiBr + KCl, IV. LiCl + KBr, and of the salt pairs with a common ion V. CdBr2 + KBr, VI. CdCl2 + KCl, VII. LiBr + LiCl, VIII. LiBr + KBr is done.  The measured ultrasonic velocities in these binary systems are compared with those calculated from various theoretical models of liquid mixtures. The validity of Free Length Theory, Collision Factor Theory, Nomoto's relation, Van Dael-Vangeel's relation, ideal mixing relation and impedance dependence relation is checked for the systems under study. The non-ideal behavior of the systems is explained in terms of inter-ionic and intermolecular interactions present in the constituents of these binary mixtures.

Some ultrasonic investigations in binary mixtures of molten salts with a common ion and reciprocal salt pair mixtures have been carried out. Prissiajnyi et al had reported data on ultrasonic velocity and adiabatic compressibilities for four molten salt pairs with a common ion. They calculated isothermal compressibility, molar ultrasonic velocity, excess molar volume and excess isothermal compressibility in such systems on the basis of a hole theory. In the present investigation, several acoustical and thermodynamically parameters of CdBr2 + KBr, CdCl2 + KCl, LiBr + LiCl and LiBr +KBr have been studied. While the first two systems are investigated at 973 K and the other two systems are studied at 1023 K. The ultrasonic velocities and adiabatic compressibilities data for these systems have been taken from the literature for these studies. The interactions prevailing in these binary mixtures have been interpreted from the obtained results.

Physico-chemical properties like ultrasonic velocity, density, viscosity and refractive index have been measured for the following four ternary systems: 1. n-hexane + p-dioxane + methanol 2. n-hexane + p-dioxane + ethyl acetate 3. Carbon tetrachloride + Pyridine + ethyl acetate 4. Carbontetrachloride + Pyridine + methanol The dielectric constant and dipole moment measurements are also made for a ternary mixture: n-hexane + p-dioxane + ethyl acetate at 30.5, 35.5 and 40.5 degrees Celsius. Using the experimentally obtained data a large number of acoustical and thermodynamical parameters e.g. adiabatic compressibility, Rao's parameter, intermolecular free length, Wada's parameter, acoustic impedance and Relative association have been studied. Free volume and internal pressure values for the systems have also been calculated. The trends of variation of these parameters have been explained in terms of the interactions present among the molecules of the constituent liquids. Using measured viscosity data, interaction energies have been found and the strength of interactions between constituents of the mixtures are also reported. The validity of the Eykman relation is checked in the case of ternary liquid systems for the first time. Auerback relation is used to predict the surface tension values for the systems under investigation. An analysis of the results obtained indicates that the response of a ternary system does not depend significantly on the aromatic or aliphatic nature of the liquids. It depends primarily on the polarity and molecular radius of the each component.

Acoustical investigations of three binary mixtures of organometallic compounds- tetrabutyltin, tributyltin chloride and dibutyltin dichloride - with tetrahydrofuran has been made at 45 degree Celsius. A large number of acoustical and thermodynamical properties, such as molar sound velocity, molar adiabatic compressibility, acoustic impedance, surface tension, available volume, co-volume, intermolecular free length, and relative association, have been evaluated for the system under study. Excess parameters such as excess ultrasound velocity, excess density, excess molar sound velocity. excess molar adiabatic compressibility, excess acoustic impedance, excess volume and excess available volume have been calculated. All three of the systems studied here are non-ideal and the results have been used to interpret the relative order of the acceptor strength of the butyltins.

We present a distributed linear model of thermoacoustic instability in form of a set of coupled PDEs including an acoustic model based on potential Euler formulation, a fully distributed fuel transport model based on advection equation, and a fuel-sensitive heat release model based on assumption of fixed flame location. The damping in the distributed model is provided on the acoustic

Microperforated plate (MPP) absorbers are perforated plates with holes typically in the submillimeter range and perforation ratios around 1%. The values are typical for applications in air at standard temperature and pressure (STP). The underlying acoustic principle is simple: It is to create a surface with a built in damping, which effectively absorbs sound waves. To achieve this, the specific acoustic impedance of a MPP absorber is normally tuned to be of the order of the characteristic wave impedance in the medium (∼400 Pa s/m in air at STP). The traditional application for MPP absorbers has been building acoustics often combined with a so called panel absorber to create an absorption peak at a selected frequency. However, MPP absorbers made of metal could also be used for noise control close to or at the source for noise control in ducts. In this paper, the possibility to build dissipative silencers, e.g., for use in automotive exhaust or ventilation systems, is investigated.

An investigation in the ultrasonic response of three binary mixtures of organometallic compounds e.g. tetrabutyltin, tributyltin chloride and dibutyltin dichloride with tetrahydrofuran is done at 45 degrees Celsius. The measured ultrasonic velocities in these mixtures are compared with those obtained from various theoretical models of liquid mixtures. The validity of Free Length Theory, Collision Factor Theory, Nomoto's relation, Van Dael-Vangeel 's relation, Ideal Mixing relation and Impedance Dependence relation is checked for the systems under study. The non-ideal behaviour of the systems has been explained in terms of the molecular interactions present in the constituents of the three mixtures.

An investigation in the acoustical response of water, carbon tetrachloride, methanol ternary mixture at its miscibility point is done at 308K. The measured ultrasonic velocities in the system are compared with those obtained from various theoretical models of liquid mixtures. The validity of Free Length Theory, Collision factor Theory, Nomoto's Relation, Van Dael-Vangeel's Relation, Ideal Mixing Relation and Impedance Dependence Relation is checked for the system under study. The non-ideal behavior of the system has been explained in terms of molecular interactions present in the constituents of the multi-component system. Excess molar volume and excess molar refractivity have been calculated at 308K from the measured density and refractive index data for the ternary mixtures. A comparative study of eight mixing rules of refraction has been carried out to test their validity for the system under study at its miscibility point. It is pointed out that all the mixing rules perform well within the limits of experimental error but the performance of Lorentz-Lorenz ( L-L)  relation and Gladstone-Dale (G-D) relation is comparatively better than those of others.

... selected on the oscilloscope and process it to FFT using a standard software SPD-GURU from Tektronix ... Thanks are also due to M/s Jagdish Lal and Om Prakash for help at various ... References [1] RC Preston, DR Bacon and RA Smith, Calibration of medical ultrasonic equipment ...

Several methods can be applied for analyses of the acoustic field in enclosed rooms namely: wave propagation, geometrical or statistical analysis. The paper presents problems related to application of the boundary elements method to modelling of acoustic field parameters. Experimental and numerical studies have been combined for evaluation of acoustic impedance of the material used for the walls of a model room. The experimental studies have been carried out by implementing a multichannel measuring system inside the constructed model of an industrial room. The measuring system allowed simultaneous measurements of the source parameters - the loudspeaker membrane vibration speed, the acoustic pressure values in reception points located inside the model space as well as phase shifts between signals registered in various reception points. The numerical modelling making use of the acoustic pressure values measured inside the analyzed space allowed determination of requested parameters of...

A detailed study of acoustical properties of commercial petrol and its various mixture samples adulterated by kerosene oil is done at 19 degrees Celsius using ultrasonic velocity data available in the literature. The variation of these parameters is discussed in terms of the nature and size of molecules of the constituents of the mixtures. It is concluded that an adulteration check meter designed to digitally display acoustic impedance will be much more reliable than the commercially available ultrasonic velocity-dependent check meter.