Investigation of frequency variations of Acoustic impedance can play an important role in identification and optimization of a musical instrument. For a simple tube, the input Acoustic impedance can be calculated by analytical methods; for complex geometry objects like wind instrument, however, it cannot be simply computed. Therefore, the impedance is measured for wind instruments. This paper is a report of the first experiment for measuring the input Acoustic impedance of Ney (an Iranian woodwind instrument). For this purpose, a pulse reflect meter device was made. To ensure correct operation of the reflect meter, in the first step, the input Acoustic impedance of a three sections step tube was measured and the results were compared with calculated results using a well-known formula. The Acoustic impedances of a Do-ney for various fingering in six case (from all holes closed to all holes opened) were measured. The results show that, contrary to what was seen for flute, the frequencies of minima of the impedance curves have some discrepancies with the frequencies of corresponding playable notes. This may be related to the role of the mouth of the instrument player in producing tones of ney.

Porosity is one of the most important petrophysical parameters, studied in the subject of reservoir characterization. Determining porosity and how it changes in hydrocarbon reservoirs is an important issue that has been addressed in various researches. In this research, Poro-Acoustic impedance (PAI) is introduced as an extended form of Acoustic impedance (AI). The difference between PAI and AI is related porosity that is directly involved in the PAI. The inclusion of porosity data in the PAI formula made porosity effective in forward modeling and inversion of seismic data. The use of PAI in the forward modeling of synthetic models increases the contrast between the subsurface layers, and the contrast increases twice as compared to the AI. Band Limited Recursive Inversion (BLRI) algorithm is used for inversion of synthetic seismograms and model-based algorithm is used for real seismic data inversion. For real data, due to the existence of well data, seismic horizons and geological information, using the basic model method for inversion is more accurate. The main difference between inversion using PAI and AI is that changes in porosity can be seen directly in the results of PAI inversion. The correlation of porosity with PAI and AI is -0.93 and -0.85, respectively, which shows that porosity has a stronger relationship with PAI. The use of PAI can be a quick and simple solution to understand porosity changes in hydrocarbon reservoirs and increase the accuracy of porosity determination in reservoirs to a great extent.

As underground hidden facilities are used for various applications, imaging systems are required for the detection and recognition of these facilities. In this paper, imaging by mechanical wave propagation in the soil is investigated. Most underground facilities can be considered as air chambers located in the middle of the soil. Air and soil have a large difference in Acoustic impedance, so underground facilities can produce a large reflective signal because the amplitude of the reflected signal depends on the difference in impedance of the two materials. Seismic and non-destructive concrete testing systems also use the process of propagation of mechanical waves in the material. Although seismic systems have been successful in the detection issue, they require several meters of space for equipment layout, and transportation complexity is also one of their problems. They are unsuitable for urban space because they are inherently designed to detect water sources at depths of several hundred meters. On the other hand, while the non-destructive concrete testing system equipment have suitable dimensions, they have low penetration depth which is impractical for this purpose. Seismic and non-destructive testing systems of concrete operate in the range of subsonic and ultrasonic waves, respectively. This research project proposes the idea that by choosing an operating frequency between the two mentioned ranges, it is possible to obtain equipment with the appropriate dimensions for imaging underground facilities. In this project we managed to image an underground constructed cylindrical cavity with the diameter of 1 meter and the depth of 4 meters. The accuracy of this method depends on the sound propagation speed in the material. Since there are accurate relationships for the propagation speed of sound in air, the diameter of the cylinder was estimated with an accuracy of about 4%, but with the measurement of propagation speed being infeasible in this project, leading to the ambiguity in the value of propagation speed of sound in soil, the values cited in several reference sites were used, giving the accuracy of 4 to 20%.

Oil companies are trying to increase production rate by improved recovery methods. Typically, oil and gas fields have been penetrated by lots of wells. The seismic inversion method is a powerful technique. This project is about inversion of 3-D seismic data to Acoustic impedance in one of the south-west oil field of Iran. In this study we checked other different inversion methods such as sparse spike and model based. We applied model based inversion method in the studied area. The input data includes seismic data, well log data, and structural interpreted data. Knowledge of the seismic wavelet is also necessary. In this study we integrated available information from seismic data, well logs and the knowledge of regional and local geology to produce detailed, spatially consistent, 3-D impedance models. The results of this study reveal that there are several reefal structures in the main reservoirs.

Surface Acoustic wave (SAW) technology is an efficient tool for precise control of microrobots and cells in biomedical and microfluidic applications. Polydimethylsiloxane (PDMS), due to its biocompatibility and flexibility, adds new capabilities to SAW systems by adjusting the base to curing agent ratios, providing more options for cell isolation, manipulation, trapping, and other applications. In this study, different compositions with ratios of 20:1, 10:1, 5:1, and 2:1 were investigated and their effects on standing surface Acoustic waves (SSAW) and the ability to control microrobots were evaluated. Experimental and simulation results show that some PDMS formulations add the ability to change the Acoustic impedance and damping to the system and operate effectively at specific points. Ultimately, the implications of these findings are important in fields such as drug delivery, tissue engineering, and microfluidic systems requiring rapid and precise control of microrobotsو and it can have a positive impact in this area.

In this paper, a leak detection method, based on an Acoustic approach, is presented for tubular systems. An energy balance methodology for Acoustic waves is proposed as a means to detect both the possible occurrence of a leak, as well as an estimation of its position and leakage flow rate. Information on the incident, transmitted, absorbed, reflected Acoustic energy and wave amplitude will enable one to determine the leakage position, as well as its flow rate. The presence of a leak will result in a change of the wall impedance. The governing equations are derived and a finite difference scheme is used to solve them. Results are presented for variations of the Acoustic energy for transmission, absorption and reflection with leak size and wave frequency. The effects of different leak sizes and pinhole positions on the propagation of an Acoustic pressure wave are studied.

In this study, five materials used for the design and manufacture of Acoustic absorbers have been investigated. The finite element method has been used with the help of COMSOL software to measure the underwater sound absorption coefficient. The method of creating an axisymmetric simulation to reduce the volume of calculations has been explained; the application of boundary conditions and the generation of Acoustic waves have also been investigated, and the effect of the mechanical properties of the materials, including Young's modulus, density, and loss coefficient, on the underwater sound absorption coefficient has been analyzed. The results show that with the increase in the Young's modulus of materials such as nitrile butadiene rubber, which inherently has a low Young's modulus; the sound absorption coefficient in the frequency range of 0.2 to 10 kHz increases significantly compared to other materials. Materials with a high loss coefficient increase the sound absorption coefficient at frequencies below 1 kHz compared to other materials. Materials such as styrene-butadiene rubber, which has a density close to that of water, have a good impedance match with the underwater environment and have excellent sound absorption coefficients in the frequency range of 2 to 10 kHz, which also depends on other material properties.

The direct way to access the petrophysical property of hydrocarbon reservoir is based on well data but due to its high cost, the seismic data has been used to obtain these parameters. For this purpose, many different methods are available and each has its own advantages and limitations. From these methods the seismic inversion is the best tool to study the reservoir characterization. The outcome of the seismic inversion is the transformation of seismic reflection data to pseudo-impedance logs at each CMP. It is therefore, the seismic inversion results facilitate better estimations of reservoir properties such as porosity. In this study the results of two different post-stack inversion methods on seismic data will compared. These are sparse-spike and model-based methods. These results were used for Acoustic impedance construction based on 2D seismic data in the Saraje Gas Field. By using this model and creation of linear regression the estimated porosity model has been achieved.

Poststack seismic inversion generally transmutes seismic amplitude to P-wave Acoustic impedance, which lacks low-frequency component due to the stacking process. This component should be compensated using well logs as a priori constraint. If this low-frequency trend is known with adequate accuracy, poststack inversion could produce precise results. Nevertheless, in most cases, the mentioned information are far from the true model. In such cases, poststack inversion results could have high uncertainty. Because there is no mode conversion at normal incidence, postsatck inversion is completely Acoustic, hence P-wave impedance is the only information which can be extracted from poststack inversion of P-wave data. In simulations prestack inversion, in addition to the P-wave Acoustic impedance, S-wave information, density, and Poisson’ s ratio can also be derived from prestack data. Thus, prestack inversion can be used to get more information than poststack inversion. The two-step process of Acoustic impedance and shear impedance by model-based inversion is replaced by one-step pre-stack simultaneous inversion. In order to apply simultaneous inversion method to our prestack seismic data, the data should be transformed from offset domain to angle domain as the first step. A useful approach is to calculate offset as a function of incidence angle, using Snell’ s Law to follow the ray path through the layers if velocity information is available. The next step is to build initial models of Acoustic impedance, shear impedance, and density. We built these initial models using sonic log, Delta-Time Shear (DTSM) log and RHOB log which were available in the interest area. There are two relationships that should hold for these wet rocks. The first relationship uses this fact that in wet clastics the ratio of the s-wave velocity over p-wave velocity should be constant within a rock layer. After reformulation of the mentioned trend, one can understand that the natural logarithm of shear impedance has a linear relationship with the natural logarithm of Acoustic impedance. The second fact uses Gardner equation. After reformulation of the Gardner relation, it is understandable that the natural logarithm of density has a linear relationship with the natural logarithm of Acoustic impedance, too. We determined k, kc, m and mc which respectively are slope of the natural logarithm of shear impedance against natural logarithm of Acoustic impedance, intercept of the natural logarithm of shear impedance against natural logarithm of Acoustic impedance, slope of the natural logarithm of density against natural logarithm of Acoustic impedance, intercept of the natural logarithm of shear impedance against natural logarithm of Acoustic impedance. Besides, we need a set of angle-dependent wavelets which are derived from angle stacks. Hence, we built three angle stacks; near-angle stack (0 to 11 degrees), middle-angle stack (11 to 20 degrees) and far-angle stack (20 to 29 degrees). Using these angle stacks, we built three statistical angle-dependent wavelets from three angle stacks. Finally, with log information, we built an initial model for Acoustic impedance and tried to solve the inversion matrix using conjugate gradient method. Solving the equation, we can derive Acoustic impedance, shear impedance, and density sections simultaneously from prestack data. Using simultaneous inversion, we identified hydrocarbon reservoir.