Includes bibliographies. / Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1977. / Microfiche copy available in the Institute Archives and Barker Engineering Library. / by William Mark Rabinowitz. / Ph.D.

Thesis. 1977. M.S.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO. / Includes bibliographical references. / M.S.

Este trabalho analisa a qualidade dos combustíveis derivados de petróleo através de suas propriedades acústicas, visando assim um monitoramento contínuo e instantâneo. Analisa a variação da impedância acústica da gasolina com acréscimo de vários componentes como: tolueno, óleo diesel, querosene e álcool anidro. Os resultados obtidos mostram uma variação significativa embora não linear da impedância acústica nos combustíveis derivados de petróleo com acréscimo de tais substâncias. / This work is related with research project focused on the development of low cost and robust quality monitoring equipment and methods, suitable for application in the production of petrochemical compounds. The main objective of this work is to assess the quality of automotive gasoline through the analysis of its acoustic properties. More specifically, pure gasoline\'s acoustic impedance (defined as the product between its density and the velocity of propagation of an acoustic wave) is analyzed with respect to the addition of toluene, kerosene, ethanol and diesel fuel. Results show that the acoustic impedance is sensitive to the addition of such components, although this relation may be non-linear in some cases.

Este trabalho analisa a qualidade dos combustíveis derivados de petróleo através de suas propriedades acústicas, visando assim um monitoramento contínuo e instantâneo. Analisa a variação da impedância acústica da gasolina com acréscimo de vários componentes como: tolueno, óleo diesel, querosene e álcool anidro. Os resultados obtidos mostram uma variação significativa embora não linear da impedância acústica nos combustíveis derivados de petróleo com acréscimo de tais substâncias. / This work is related with research project focused on the development of low cost and robust quality monitoring equipment and methods, suitable for application in the production of petrochemical compounds. The main objective of this work is to assess the quality of automotive gasoline through the analysis of its acoustic properties. More specifically, pure gasoline\'s acoustic impedance (defined as the product between its density and the velocity of propagation of an acoustic wave) is analyzed with respect to the addition of toluene, kerosene, ethanol and diesel fuel. Results show that the acoustic impedance is sensitive to the addition of such components, although this relation may be non-linear in some cases.

Energy quantities, which are calculated from pressure and particle velocity, yield a great deal of information about acoustic fields. Errors in pressure or particle velocity estimation lead to bias errors the estimation of energy quantities. The bias errors arise from different probe configurations and processing methods. Two processing methods are examined: the traditional method and the recently developed Phase and Amplitude Gradient Estimation (PAGE) method. These two methods are compared to investigate how each estimates pressure and particle velocity and the subsequent bias errors in a plane wave, standing wave, and spherical spreading wave field. Analytical expressions are derived for the energy quantity estimation using ideal one-dimensional probes. A simulation of the field from a baffled circular piston and measurements using ideal two-dimensional probes is computed. Compared to the traditional method, the PAGE method significantly extends the range of frequencies for which the results are accurate. It is found that a probe with a center microphone significantly reduces the estimation error and extends the usable range of frequencies. The PAGE method with unwrapping, perfectly matches the analytical results for plane waves, while the traditional method is only good at wavelengths that are large compared to the probe size. Furthermore, the PAGE method has a constant bias error in spherical wave fields due to the 1/r decrease in pressure. The traditional method has a frequency dependent bias error that is much worse at higher frequencies. Lastly, the PAGE method has the same or worse error for the standing wave. As an application of energy quantities, acoustic intensity is used to develop an equivalent source model for jet noise from an F-22 at military and afterburner engine conditions. An optimization is used to find the best-matching wavepacket model for measured intensity vectors. The results are compared to another intensity method of estimating the source region and source directivity, and the two methods have good agreement.

Philosophiae Doctor - PhD / Investigation of the acoustic impedance variations in the upper shallow marine sandstone reservoirs was extensively studied from 10 selected wells, namely: F-O1, F-O2, E-M4, E-CN1, E-G1, E-W1, F-A10, F-A11, F-A13, and F-L1 in the Bredasdorp Basin, offshore, South Africa. The studied wells were selected randomly across the upper shallow marine interval with the purpose of conducting a regional study to assess the variations in the acoustic impedance across the reservoirs using wireline log and core data. The datasets used in this study were geophysical wireline logs, conventional core analysis, geological well completion reports, core plugs, and core samples. The physical rock properties such as lithology, fluid type, and hydrocarbon bearing zone were identified while different parameters like the volume of clay, porosity, and water saturation were quantitatively estimated. The reservoirs were penetrated at a different depth ranging from a shallow depth of 2442m at well F-L1 to a deeper depth of 4256.7m at well E-CN1. The average volume of clay, average effective porosity from wireline log, and average water saturation ranged from 8.6%- 43%, 9%- 16% and 12%- 68%, respectively. Porosity distribution was fairly equal across the field from east to west except in well F-A10, F-A13, and F-A11 where a much higher porosity was shown with F-A13 showing the highest average value of 16%. Wells E-CN1, E-W1, F-O1, F-L1 and E-G1 had lower porosity with E-CN1 showing the lowest average value of 9%. The acoustic properties of the reservoirs were determined from geophysical wireline logs in order to calculate acoustic impedance and also investigate factors controlling density and acoustic velocities of these sediments. The acoustic impedance proved to be highest on the central to the western side of the field at E-CN1 with an average value of 11832 g/cm3s whereas, well F-A13 reservoir in the eastern side of the field proved to have the lowest average acoustic impedance of 9821 g/cm3s. There was a good linear negative relationship between acoustic impedance and porosity, compressional velocity vs porosity and porosity vs bulk density. A good linear negative relationship between acoustic impedance and porosity was obtained where the reservoir was homogenous, thick sandstone. However, interbedded shale units within the reservoir appeared to hinder a reliable correlation between acoustic impedance and porosity. The cross-plots results showed that porosity was one of the major factors controlling bulk density, compressional velocity (Vp) and acoustic impedance. The Gassmann equation was used for the determination of the effects of fluid substitution on acoustic properties using rock frame properties. Three fluid substitution models (brine, oil, and gas) were determined for pure sandstones and were used to measure the behaviour of the different sandstone saturations. A significant decrease was observed in Vp when the initial water saturation was substituted with a hydrocarbon (oil or gas) in all the wells. The value of density decreased quite visibly in all the wells when the brine (100% water saturation) was substituted with gas or oil. The fluid substitution affected the rock property significantly. The Vp slightly decreases when brine was substituted with water in wells F-A13, F-A10, F-O2, F-O1 F-A11, F-L1, and E-CN1. Wells E-G1, E-W1, and E-M4 contain oil and gas and therefore showed a notable decrease from brine to oil and from oil to gas respectively. Shear velocity (Vs) remained unaffected in all the wells. The acoustic impedance logs showed a decrease when 100% water saturation was replaced with a hydrocarbon (oil or gas) in all the wells. Clay presence significantly affects the behaviour of the acoustic properties of the reservoir rocks as a function of mineral type, volume, and distribution. The presence of glauconite mineral was observed in all the wells. Thirty-two thin sections, XRD and SEM/EDS from eight out of ten wells were studied to investigate lithology, diagenesis and the effect of mineralogy on porosity and acoustic properties (Compressional velocity and bulk density) within the studied reservoir units. Cementation (calcite and quartz), dissolution, compaction, clay mineral authigenesis, and stylolitization were the most significant diagenetic processes affecting porosity, velocity, and density.Well E-CN1 reservoir quality was very poor due to the destruction of intergranular porosity by extensive quartz and illite cementation, and compaction whereas well F-A13 show a highly porous sandstone reservoir with rounded monocrystalline quartz grain and only clusters of elongate to disc-like, authigenic chlorite crystals partly filling a depression within altered detrital grains. Overall, the results show that the porosity, lithology mineralogy, compaction and pore fluid were the major factors causing the acoustic impedance variations in the upper shallow marine sandstone reservoirs. / 2021-09-01

How important is the player???s vocal tract in clarinet and saxophone performance? Acoustician???s opinions have ranged from ???negligible??? [Backus (1985), JASA 78, 17] to ???vocal tract resonance frequencies must match the frequency of the required notes??? [Clinch et al. (1982), Acustica 50, 280]. Musicians??? opinions are similarly varied. To understand how the tract-reed-bore system interacts, acoustical measurements of performers??? vocal tracts during playing were made using measurement heads mounted in the mouthpieces of a clarinet and a tenor saxophone. Acoustic impedance spectra of the tenor and soprano saxophone bores were also measured for all standard fingerings, and some others. For fingerings high in the tenor saxophone???s second register, bore impedance peaks downstream decrease with increasing pitch. Above the first 2.7 octaves, peak values fall below 30 MPa.s.m-3 and this ends the standard range available to amateurs. To play the higher altissimo notes, experts produced strong vocal tract resonances upstream with impedances 10-40 MPa.s.m-3 tuned to sound the desired note. While expert saxophonists adjust their vocal tract thus for altissimo playing, inexperienced players do not, and consequently cannot produce these notes. The smoothly rising clarinet glissando solo opening Gershwin???s Rhapsody in Blue was also investigated. Partially uncovering an open finger-hole smoothly raises clarinet resonances in the lower register, allowing continuous increases in playing pitch. When pitch bending in the second (clarino) register, experienced players produced strong tract resonances with impedances up to 60 MPa.s.m-3, comparable in magnitude with those of the clarinet bore (40-50 MPa.s.m-3). Thus during the glissando, sounding pitch is controlled by smoothly varying a strong resonance in the player???s vocal tract. The phase of the reed impedance is shown to make downwards pitch bending easier than upwards. Similar vocal tract adjustments were observed on the clarinet and saxophone for other advanced techniques such as bugling and multiphonic selection. During normal playing, although experienced players produced vocal tract impedance peaks with only moderate magnitude, these peaks were adjusted systematically to frequencies about 150 Hz higher than the sounding pitch (determined by strong bore resonances). This strategy may avoid the effects of small unwanted tract-bore interactions on sounding pitch.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographic references (p.75-76).

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xvi, 195 p.; also includes graphics. Includes bibliographical references (p. 183-195). Available online via OhioLINK's ETD Center