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Advanced-degree dissertations in acousticsEditor’s note:Abstracts of Doctoral and Master’s theses will be we

comed at all times. Please note that they must be double spaced, limit200 words, must include the appropriate PACS classification numbersformatted as shown below~don’t make the editor retype them, please!!. Theaddress for obtaining a copy of the thesis is helpful. Please submitcopies.

Characterization of cylindrical objects placed in aplane-stratified acoustic waveguide for shallow waterapplications [43.30.Pc, 43.20.Fn, 43.60.Pt]-—Christophe Rozier,Laboratorie des Signaux et Systemes (CNRS-SUPELEC), PlateaMoulon, 91192 Gif-sur-Yvette Cedex, 16 October 1996 (French doctorUniversity Denis Diderot, Paris).The inversion of closed cylindrical objectof smooth cross-sectional contours in a planar acoustic waveguide is intigated. Time-harmonic contour integral formulations of the pressurederived for both vibrating bodies and passive-penetrable or -impenetrobstacles immersed in a homogeneous water layer of finite depth abohard or penetrable bottom, which models a shallow water configuraPressure values follow by the Nystrom method, the Green’s function bcalculated via a hybrid ray-mode representation. At one given frequetwo inversion problems are attacked from the resulting synthetic data:~i! thenormal velocity distribution on the contour of a vibrating body is retrievby SVD with a Tikhonov filter whose regularization parameter is foundtheL curve;~ii ! the contour of a convex or concave obstacle illuminatedline sources at a large range in water is constructed iteratively by a comfamily approach where the scattered pressure is represented as a sGreen’s functions whose source locations evolve with the retrieved conThe mathematical basis and the numerical machinery of the solution mods are detailed. Simulations are carried out for several objects fromand high-frequency exact and noisy data, in near-field and far-field meament configurations, and with partial or full coverage of water column.

Thesis advisor: Dominique Lesselier.

Frequency specificity of the auditory brainstem (ABR) and themiddle latency (MLR) responses [43.64.Qh, 43.64.Ri]—Margaret A.Oates,Doctoral Program in Speech and Hearing Sciences, GraduCenter, City University of New York, New York, NY 10036, February 1(Ph.D.).Three issues concerning the frequency specificity of the ABRMLR to tonal stimuli were examined:~1! recording the ABR to high-intensity low-frequency stimuli;~2! the suggestion that the MLR providesmore frequency-specific response to low-frequency tones compared tABR; and ~3! the use of nonlinear- versus linear-gated stimuli to improthe frequency specificity of these responses. The frequency specificithese evoked potentials was investigated~12 normal subjects! using the

1202 J. Acoust. Soc. Am. 101 (2), February 1997 0001-4966/97/10

ibution subject to ASA license or copyright; see http://acousticalsociety.org/

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high-pass noise~HPN! masking/derived response~DR! technique. Stimuliwere 500- and 2000-Hz exact-Blackman and linear-gated tones presen80 dB peak-to-peak equivalent SPL. Cochlear contributions to ABRV-V8and MLRNa-Pa were assessed by:~1! effects of HPN masking on ABR/MLR amplitudes and latencies; and~2! response amplitude profiles asfunction of derived-band center frequency. The HPN and DR results icate good frequency specificity for both the ABR and MLR. Maxima in tamplitude profiles occurred in the 500- and 707-Hz derived bands forsponses to the 500-Hz tones and in the 1410- and 2000-Hz derived banresponse to the 2000-Hz stimuli. No significant differences were foundthe frequency specificity of:~1! ABR versus MLR;~2! responses to 500- vs2000-Hz tones; and~3! responses to exact-Blackman versus linear-gatones.

Thesis advisor: Dr. David R. Stapells.

Thesis may be obtained from University Microfilms International, 3North Zeeb Road, Ann Arbor, MI 48106-1346. Publication numb9618088 in Dissertation Abstracts International Vol.~57!, issue 2B, p. 973.

Critical and uncritical low-frequency relaxation processes inmixtures near the critical point of stratification [43.35.Bf] (inEnglish and Russian)—Sirojiddin Mirzaev, Heat Physics DepartmenAcademy of Sciences Republic of Uzbekistan, Chilonzor ‘‘C,’’ Katartal700135, Tashkent, Uzbekistan, 16 May 1996 (Ph.D.).The aim of this thesisis the experimental study of critical and uncritical low-frequency relaxatprocesses in mixtures with small values of critical sound absorptions. Infirst chapter of the thesis a review of experimental and theoretical workinvestigation of acoustical properties of liquids having critical point strafication ~CPS! was made. Works which study chemical reaction kinetnear CPS are analyzed separately. The influence of closeness to cpoints on the rate of a molecular reaction, is discussed. In the second cha brief description of the experimental technique is given. A descriptionthe experimental installation aimed to study liquid–liquid phase diagranear the boiling temperature of solutions having CPS is presented.results of this investigation, consisting of two main parts is dealt withchapters three and four. The third chapter describes the basic resuinvestigation by means of acoustical spectroscopy of mixtures, methaheptan, methanol–cychlohexane, and methanol–benzene–water in aregion of temperatures near the critical one. A description of the analysacoustical absorption spectra is also presented. The critical attenuatianalyzed in terms of the dynamic scaling theory of Ferrell–BhattachardIn the fourth chapter the results of investigation of the kinetics of mono-bimolecular reactions near CPS of three-component mixtucyclohexanol–water–methanol and acetic acid–heptane–water are gKinetical parameters characterizing mono- and bimolecular reactions westablished not to depend on the closeness to the critical point.

Thesis advisor: Academician, Prof. P. Khabibullaev.

12021(2)/1202/1/$10.00 © 1997 Acoustical Society of America

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