Tesis sobre el tema "Acoustic thermometry. Speed of sound"
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THIRUMALAI, RAJ SRIJITH BANGARU. "Acoustic Thermometry Based on Accurate Measurements of Speed of Sound in Air". Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2934680.
Texto completoBurger, Gert Cloete. "Optimisation of the pulse-echo method with an application to acoustic thermometry". Thesis, Cape Peninsula University of Technology, 2010. http://hdl.handle.net/20.500.11838/1105.
Texto completoIn acoustics, pulse echo methods are well known as a means of measuring time of Hight. Traditional techniques for generating acoustic waves in solid ferromagnetic waveguides include piezoelectric, capacitive and magnetostriction. Piezoelectric and capacitive techniques are preferred due to the inefficiency of magnetostriction caused by electro-mechanical coupling losses and the fact that most ferromagnetic materials show low levels of magnetostriction. The aim of this study was to optimise the magnetostrictive effects for sensing applications based on a ferromagnetic waveguide using the pulse echo method. The results obtained were implemented in the design of an acoustic thermometer. Two configurations for signal generation and recovery were examined, the use of a single wound copper coil acting as a transceiver coil, and the use of separate transmit and receive coils. Results obtained using the latter configuration indicated better signal to noise ratio's and provided the flexibility to manipulate the point of signal recovery. The pulse echo method was implemented and optimised. An acoustic thermometer based on an existing design was developed by inducing a partial reflection from a set position in the waveguide, defining a sensing probe. Awareness of the elastic properties of the waveguide material enabled the guaging of its temperature by measuring the acoustic pulse velocity in the probe. The accuracy of the instrument was increased through signal conditioning, examined together with cross correlation and an increased sampling frequency. Systematic errors were resolved through calibration, giving the instrument an overall accuracy of ±O.56"C for the range of temperatures between 2O"C and 400"C.
Guthrie, Vanessa M. "Dynamics of eastern boundary currents and their effects on sound speed structure". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Jun%5FGuthrie.pdf.
Texto completoThesis Advisor(s): Mary L. Batteen, John A. Colosi. "June 2006." Includes bibliographical references (p. 69-73). Also available in print.
Angerstein, Jeanette Louise. "A hemispherical acoustic resonator for the measurement of the speed of sound in gases". Thesis, University College London (University of London), 2000. http://discovery.ucl.ac.uk/1382240/.
Texto completoSun, Chao. "Acoustic characterisation of ultrasound contrast agents at high frequency". Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8093.
Texto completoTombul, Serdar. "A numerical study of the validity regimes of weak fluctuation theory for ocean acoustic propagation through random internal wave sound speed fields". Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion.exe/07Mar%5FTombul.pdf.
Texto completoThesis Advisor(s): John Colosi. "March 2007." Includes bibliographical references (p. 81-82 ). Also available in print.
Li, Qi. "Acoustic noise emitted from overhead line conductors". Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/acoustic-noise-emitted-from-overhead-line-conductors(90a5c23c-a7fc-4230-bbab-16b8737b2af2).html.
Texto completoLaferriere, Alison Beth. "K-distribution fading models for Bayesian estimation of an underwater acoustic channel". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/63080.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (p. 113-114).
Current underwater acoustic channel estimation techniques generally apply linear MMSE estimation. This approach is optimal in a mean square error sense under the assumption that the impulse response fluctuations are well characterized by Gaussian statistics, leading to a Rayleigh distributed envelope. However, the envelope statistics of the underwater acoustic communication channel are often better modeled by the K-distribution. In this thesis, by presenting and analyzing field data to support this claim, I demonstrate the need to investigate channel estimation algorithms that exploit K-distributed fading statistics. The impact that environmental conditions and system parameters have on the resulting distribution are analyzed. In doing so, the shape parameter of the K-distribution is found to be correlated with the source-to-receiver distance, bandwidth, and wave height. Next, simulations of the scattering behavior are carried out in order to gain insight into the physical mechanism that cause these statistics to arise. Finally, MAP and MMSE based algorithms are derived assuming K-distributed fading models. The implementation of these estimation algorithms on simulated data demonstrates an improvement in performance over linear MMSE estimation.
by Alison Beth Laferriere.
S.M.in Electrical Engineering and Computer Science
Siemes, Kerstin. "Establishing a sea bottom model by applying a multi-sensor acoustic remote sensing approach". Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209381.
Texto completoChapters 4 and 5 are adapted from published work, with permission:
DOI:10.1121/1.3569718 (link: http://asadl.org/jasa/resource/1/jasman/v129/i5/p2878_s1) and
DOI:10.1109/JOE.2010.2066711 (link: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=5618582&queryText%3Dsiemes)
In reference to IEEE copyrighted material which is used with permission in this thesis, the IEEE does not endorse any of the Université libre de Bruxelles' products or services.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
De, Man Pierre. "Contrôle actif du rayonnement acoustique des plaques: une approche à faible autorité". Doctoral thesis, Universite Libre de Bruxelles, 2004. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211180.
Texto completoLe contrôle actif à faible autorité, pour lequel le Laboratoire de Structures Actives a développé une expertise dans le domaine de l'amortissement et du contrôle actif des vibrations, est une solution attractive par sa simplicité de mise en oeuvre. Le plus souvent implémenté sous la forme d'un contrôle décentralisé constitué de boucles indépendantes, le contrôle à faible autorité bénéficie de certaines garanties de stabilité et de robustesse.
Bien que notre stratégie de contrôle puisse s'appliquer à n'importe quel type de plaque, l'application considérée dans ce travail a été motivée par le contexte socio-économique actuel en rapport avec les nuisances acoustiques. Il était en effet intéressant d'évaluer la stratégie de contrôle pour le problème de la transmission acoustique d'un vitrage. La stratégie de contrôle se divise en deux étapes. Tout d'abord le développement d'un capteur unique destiné à fournir une mesure représentative du bruit rayonné par une plaque en basse fréquence. Deux capteurs de vitesse volumétrique (l'un discret, l'autre distribué) ont ainsi été développés et évalués expérimentalement.
Ensuite, une procédure d'optimisation de l'emplacement d'un ensemble d'actionneurs pilotés en parallèle est proposée. L'objectif de cette phase d'optimisation est de forcer la réponse fréquentielle du système à posséder les propriétés d'un système colocalisé. La stratégie de contrôle est ensuite évaluée sur deux structures expérimentales.
/ This thesis is concerned with a low authority active control strategy applied to the sound radiation control of a baffled plate. Since the development of active control ,numerous researchers have studied its application to acoustical or vibroacoustical problems using either the modern control theory or other methods based rather on the understanding of the physics of the problem. Vibroacoustical active control has lead to the definition of radiation modes allowing to describe the radiated sound of a plate in an appropriate manner for active control purposes.
Low autorithy control (LAC), for which the Active Structures Laboratory has gained an expertise for active vibration control applications is an interesting solution for its implementation simplicity. Most of the time it consists of several decentralized control loops, and benefits from guaranteed stability and robustness properties. Although our control strategy can be applied to any kind of plates, the application considered here has been motivated by the present socio-economical context related to noise annoyances. The active control strategy has been applied the problem of the sound transmission loss of glass plates (windows). This strategy is in two steps :first a volume velocity sensor is developed as to give a measure representative of the radiated sound at low frequencies.
Two sensors have been developed (one discrete and one distributed) and experimentally tested. Next, an optimisation strategy is proposed which allow to locate on the plate a set of several actuators driven in parallel. The goal of this optimisation task is to obtain an open-loop frequency response which behave like a collocated system. The control strategy is finally evaluated on two plate structures.
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished
Prabhudesai, Gaurav. "Fluctuations in turbulent flows". Thesis, Université Paris sciences et lettres, 2021. http://www.theses.fr/2021UPSLE001.
Texto completoIn this thesis, we study the velocity and temperature fluctuations in a turbulent flow and their implications on the propagation of acoustic waves in turbulence. The first part is devoted to the study of the spontaneous generation of temperature fluctuations by a turbulent flow. We demonstrate that these temperature fluctuations originate from two types of intermittent structures, vorticity filaments and dissipative structures. In the second part, we study the spatio-temporal fluctuations of velocity, using the coherence function. We demonstrate that the coherence function results from the sweeping of the velocity fluctuations in the inertial range by the slower fluctuations of the integral scale. The sweeping effect is particularly interesting for the study of turbulent flows, because it does not come within the scope of Kolmogorov’s K41 theory. Finally, we study the propagation of acoustic waves through a turbulent flow and in particular phase and amplitude fluctuations. We show that phase fluctuations can be deduced from the coherence function of turbulent speed fluctuations. These fluctuations thus result from a sweeping effect of the acoustic wave by the turbulent flow. We also measure the variation in the speed of sound induced by a multiple scattering effect of the turbulent flow
Guillou, Arnaud. "Détermination de la constante de Boltzmann au plus haut niveau d’exactitude par spectroscopie acoustique dans un résonateur quasi sphérique : Vers une nouvelle définition de l’unité internationale de température". Thesis, Paris, CNAM, 2012. http://www.theses.fr/2012CNAM0843/document.
Texto completoSince 2005, there is an important interest in the international metrology community fornew accurate determinations of the Boltzmann constant kB ; the purpose is to redefine in2015 the unit of thermodynamic temperature, the kelvin. Currently, five techniques areimplemented for determining kB with the objective to achieve a relative uncertainty below1 × 10−6. The method used in the present work is based on acoustic measurements.The Boltzmann constant is linked to the speed of sound u in a noble gas by the virial acousticalequation. The method described here consists in measuring u inside a quasi-sphericalacoustic resonator of inner volume of 0.5 L filled with argon. Measurements are performedduring an isotherm process at the temperature of the triple point of water, T = 273.16 K,at static pressures P from 0.05 MPa to 0.7 MPa. The Boltzmann constant is then determinedby estimating u at zero pressure limit with a polynomial regression.In the present work an acoustic wave propagation model within a quasi-spherical resonatoris defined. Also, the technical means used to carefully control the parameters of theexperiment with an effect on the measurement of u (like temperature, static pressure, gascomposition, etc.) are presented. New exprimental methods and data analyses are described,like the measurement of the radius of the resonator by electromagnetic spectroscopy,as well as the use of the Allan deviation as an efficient tool to study the gas impuritypresence during a long-term experience. Systematic effects are analyzed and corrected. Insome cases the corrections are based on analytical models like the thermal layer boundaryeffect. In other cases, empirical correction functions are proposed, as for the case of changesin the measurements of u related to the continuous gas flow, which was experimentally characterizedin the present work.Finally, the analysis of the data acquiered in 2009 at LCM/LNE-CNAM during two isothermprocesses using argon is presented. This leads to the value kB = 1.3806475 (16) ×10−23 J · K−1, i.e. with a relative uncertainty of 1.14 × 10−6
Lowe, Steven. "Quantitative measurements of temperature using laser-induced thermal grating spectroscopy in reacting and non-reacting flows". Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277375.
Texto completoSpa, Carvajal Carlos. "Time-domain numerical methods in room acoustics simulations". Doctoral thesis, Universitat Pompeu Fabra, 2009. http://hdl.handle.net/10803/7565.
Texto completoEn aquesta Tesi hem centrat el nostre anàlisis en els mètodes basats en el comportament ondulatori dins del domini temporal. Més concretament, estudiem en detall les formulacions més importants del mètode de Diferències Finites, el qual s'utilitza en moltes aplicacions d'acústica de sales, i el recentment proposat mètode PseudoEspectral de Fourier. Ambdós mètodes es basen en la formulació discreta de les equacions analítiques que descriuen els fenòmens acústics en espais tancats.
Aquesta obra contribueix en els aspectes més importants en el càlcul numèric de respostes impulsionals: la propagació del so, la generació de fonts i les condicions de contorn de reactància local.
Room acoustics is the science concerned to study the behavior of sound waves in enclosed rooms. The acoustic information of any room, the so called impulse response, is expressed in terms of the acoustic field as a function of space and time. In general terms, it is nearly impossible to find analytical impulse responses of real rooms. Therefore, in the recent years, the use of computers for solving this type of problems has emerged as a proper alternative to calculate the impulse responses.
In this Thesis we focus on the analysis of the wavebased methods in the timedomain. More concretely, we study in detail the main formulations of FiniteDifference methods, which have been used in many room acoustics applications, and the recently proposed Fourier PseudoSpectral methods. Both methods are based on the discrete formulations of the analytical equations that describe the sound phenomena in enclosed rooms.
This work contributes to the main aspects in the computation of impulse responses: the wave propagation, the source generation and the locallyreacting boundary conditions.
Argo, Theodore F. 1982. "Laboratory measurements of sound speed and attenuation of water-saturated granular sediments". Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-05-5811.
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Chang, Wei-Ju y 張維儒. "Acoustic Pulse Propagation in a Fluctuating Ocean with Range- Dependent Sound-Speed Profile". Thesis, 1996. http://ndltd.ncl.edu.tw/handle/01854295189485298956.
Texto completo國立交通大學
電信工程研究所
84
When an acoustic pulse in a random fluctuating ocean with a deterministic sound-speed profile, it is distorted since the every frequency component experience different extents of scattering from the random inhomogeneity and echo numbers. Here, the split-step method is used to simulate an acoustic pulse with a 3kHz carrier propagating through a turbulent ocean with range- independent / -dependent sound-speed profiles. It is found that (1) For a single frequency acoustic beam, the normalized varianc of amplitude fluctuation is increased when the fluctuation strength increases or the scale length decreases; (2) The ocean is a frequency-selective fading channel; (3) The received pulse profile is dependent on the received depth, sound speed distribution, fluctuation strengthand scale length of turbulence in oceans; (4) The rms pulsewidth is broadenedby several times its initial values as a consequence of pulse echoes and pulse wandering of every pulse realization of the ensemble; (5) The rms pulsewidth is increased when the fluctuation strength increases or the scale length decreases; and (6) The statistical properties of the propagating pulse are similar for both the range-independent and -dependent cases in the mean square sense.
Horoshenkov, Kirill V., David C. Hughes y A. Cwizen. "The sound speed and attenuation in loose and consolidated granular formulations of high alumina cements". 2003. http://hdl.handle.net/10454/3691.
Texto completoClinkers of high alumina cements are separated into three granular formulations with particle sizes in the range 0.6-0.71 mm, 0.71-1.18 mm and greater than 1.18 mm. These are used to manufacture consolidated samples of porous concrete in an autoclave. The acoustic and microscopic properties of loose and consolidated porous samples of concrete are investigated using both experimental methods and mathematical modelling. Values of porosity, flow resistivity, tortuosity and parameters of the pore size distribution are determined and used to predict closely the sound speed, acoustic attenuation and normal incidence absorption coefficient of these materials. It is shown that high alumina cements do not require additional binders for consolidation and that the structural bonds in these cements are developed quickly between individual clinkers in the presence of water. The hydration product build-up during the consolidation process is insignificant which ensures good acoustic performance of the consolidated samples resulting from a sufficient proportion of the open pores. The value of porosity in the consolidated samples was found to be around 40%, which is close to that measured in some commercial acoustic absorbers. This work provides a foundation for the development of acoustically efficient and structurally robust materials, which can be integrated in environmentally sustainable concrete and masonry structures.
Dakin, Del Thomas. "In situ sensing to enable the 2010 thermodynamic equation of seawater". Thesis, 2016. http://hdl.handle.net/1828/7713.
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0415
0986
TDakin@UVic.ca
Atalick, Stefan. "Confocal acoustic holography for non-invasive 3D temperature and composition measurement". Thesis, 2007. http://hdl.handle.net/1828/123.
Texto completoGuo, Hao. "Mtemp: An Ambient Temperature Estimation Method Using Acoustic Signal on Mobile Devices". 2021. https://scholarworks.umass.edu/masters_theses_2/1051.
Texto completoYin, Wen. "Diffusive Acoustic Confocal Imaging System (DACI): a novel method for prostate cancer diagnosis". Thesis, 2017. https://dspace.library.uvic.ca//handle/1828/8910.
Texto completoGraduate
2018-12-06
Nowak, Till. "Untersuchung von akustischen Strömungen im kHz- und GHz-Bereich". Doctoral thesis, 2014. http://hdl.handle.net/11858/00-1735-0000-0022-5F17-6.
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