Dissertations / Theses on the topic 'Scanning laser Doppler vibrometry'
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Salman, Muhammad. "Continuous scanning laser doppler vibrometry for synchronized array measurements: applications to non-contact sensing of human body vibrations." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45792.
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Laser Doppler Vibrometry (LDV) is a non-contact technique for sensing surface vibrations. Traditionally, LDV uses one or more fixed beams to measure the vibrational velocity of specific points and orientations. In order to measure an angular velocity at least two laser beams are required. Instead, this research proposes to develop a Continuous Scanning Laser Doppler Vibrometer (CSLDV) technique, based on a single laser beam continuously sweeping the area of interest using a scanning mirror. Linear scans allow the measurement of normal and angular velocity while circular scans allow the measurement of normal velocity and two angular velocities. The first part of the study analyzes the performance of rigid body models of both the short line and circular scans (< 1 cm) for measuring low broadband frequency vibrations of gel samples. This thesis focused on low frequency broadband vibration since natural human body vibrations (such as tremor or breathing) are typically below a few hundred hertz. Results for normal and angular velocity measurements are validated against conventional method of using two fixed LDVs. The second part of this research investigates the CSLDV technique for longer scans (< 5 cm). These long scans will be used to act as an array of virtual transducers at multiple points along the scanning path of the single laser beam; thus yielding similar information obtained using an array of several real fixed LDVs. A practical challenge encountered when using CSLDV is speckle noise, that is generated when a coherent light source is reflected back from an optically rough surface. The effect of speckle noise will be quantified by varying different parameters such as scan lengths, scanning frequency, target to sensor distance and the amplitude of excitation. These parameters will be optimized in order to reduce the error of vibration measurements obtained from the CSLDV. Such systems will be used to monitor multiple degrees of freedom of human skeletal muscle vibrations for elastography purposes. The forced vibration of human muscles will be analyzed using these CSLDV techniques.
Overall contributions of this work include: (1) Validation of rigid body models of both short line and circular scans CSLDV for broadband low frequency linear and angular velocity measurements; (2) application to sensing natural human body vibrations (e.g., hand tremors); (3) replacement of an array of vibration sensors by a single long line scan CSLDV. (4) development of a dynamic elastography technique for skeletal muscles using CSLDV.
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Martarelli, Milena. "Exploiting the laser scanning facility for vibration measurements." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248035.
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Blotter, Jonathan D. "Structural energy and power flow using a scanning laser Doppler vibrometer." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-151157/.
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Rajm, Martin. "Laserový vibrometr s 2D rozmítáním." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219813.
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This thesis deals in the theoretical part with the non-contact vibration measurement by single point Laser Doppler vibrometer and it concretes constructions used in practice. It deals also with the possibilities of the laser beam scanning to measure the vibrations in the plane and there are also listed suitable-commercial systems for this solution. Mentioned sweep is immediately necessary for 2D scanning vibrometer construction. In the practical part, the single-point laser vibrometer OFV-5000 was expanded by scanning galvo system, supplemented by a measuring cards for signal acquisition from the vibrometer and suitable control hardware was chosen for mentioned laser. For the resulting hardware assembly was designed and implemented in LabVIEW measurement software, to control the 2D scanning system, to set the position of the laser beam and to process and to visualize of measured vibration signals in the plane. The functionality of the developed measuring system was checked by performed measurement and visualization of the velocity vibration of restraint girder, excited by shaker.
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Strean, R. Flynt. "Characterization of laser noise in free-free beam structures using a Scanning Laser Doppler Vibrometer." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-02132009-171026/.
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Zeng, Xiandi. "The estimation and statistical inferences of the position and orientation of a scanning laser Doppler vibrometer." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-10302008-063011/.
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Manwill, Daniel Alan. "Scanning Laser Registration and Structural Energy Density Based Active Structural Acoustic Control." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2396.
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To simplify the measurement of energy-based structural metrics, a general registration process for the scanning laser doppler vibrometer (SLDV) has been developed. Existing registration techniques, also known as pose estimation or position registration, suffer from mathematical complexity, instrument specificity, and the need for correct optimization initialization. These difficulties have been addressed through development of a general linear laser model and hybrid registration algorithm. These are applicable to any SLDV and allow the registration problem to be solved using straightforward mathematics. Additionally, the hybrid registration algorithm eliminates the need for correct optimization initialization by separating the optimization process from solution selection. The effectiveness of this approach is demonstrated through simulated application and by validation measurements performed on a specially prepared pipe. To increase understanding of the relationships between structural energy metrics and the acoustic response, the use of structural energy density (SED) in active structural acoustic control (ASAC) has also been studied. A genetic algorithm and other simulations were used to determine achievable reduction in acoustic radiation, characterize control system design, and compare SED-based control with the simpler velocity-based control. Using optimized sensor and actuator placements at optimally excited modal frequencies, attenuation of net acoustic intensity was proportional to attenuation of SED. At modal and non-modal frequencies, optimal SED-based ASAC system design is guided by establishing general symmetry between the structural disturbing force and the SED sensor and control actuator. Using fixed sensor and actuator placement, SED-based control has been found to provide superior performance to single point velocity control and very comparable performance to two-point velocity control. Its greatest strength is that it rarely causes unwanted amplifications of large amplitude when properly designed. Genetic algorithm simulations of SED-based ASAC indicated that optimal control effectiveness is obtained when sensors and actuators function in more than one role. For example, an actuator can be placed to simultaneously reduce structural vibration amplitude and reshape the response such that it radiates less efficiently. These principles can be applied to the design of any type of ASAC system.
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Jones, Cameron Bennion. "Development and Validation of a Vibration-Based Sound Power Measurement Method." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/9260.
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The International Organization for Standardization (ISO) provides no vibration-based sound power measurement standard that provides Precision (Grade 1) results. Current standards that provide Precision (Grade 1) results require known acoustic environments or complex setups. This thesis details the Vibration Based Radiation Mode (VBRM) method as one approach that could potentially be used to develop a Precision (Grade 1) standard. The VBRM method uses measured surface velocities of a structure and combines them with the radiation resistance matrix to calculate sound power. In this thesis the VBRM method is used to measure the sound power of a single-plate and multiple plate system. The results are compared to sound power measurements using ISO 3741 and good alignment between the 200 Hz and 4 kHz one-third octave band is shown. It also shows that in the case of two plates separated by a distance and driven with uncorrelated sources, the contribution to sound power of each individual plate can be calculated while they are simultaneously excited. The VBRM method is then extended to account for acoustically radiating cylindrical geometries. The mathematical formulations of the radiation resistance matrix and the accompanying acoustic radiation modes of a baffled cylinder are developed. Numberical sound power calculations using the VBRM method and a boundary element method (BEM) are compared and show good alignment. Experimental surface velocity measurements of a cylinder are taken using a scanning laser Doppler vibrometer (SLDV) and the VBRM method is used to calculate the sound power of a cylinder experimentally. The results are compared to sound power measurements taken using ISO 3741.
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Iverson, Thomas Z. "Signature Stability in Laser Doppler Vibrometry." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1497386740815576.
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Himes, Benjamin John. "Development and Analysis of a Vibration Based Sleep Improvement Device." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/9168.
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Many research studies have analyzed the effect that whole-body vibration (WBV) has on sleep, and some have sought to use vibration to treat sleep disorders such as insomnia. It has been shown that low frequencies (f < 2Hz) are generally sleep inducing, but oscillations of this frequency are typically difficult to achieve using electromagnetic vibration drives. In the research that has been performed, optimal vibration parameters have not been determined, and the effects of multiple vibration sources vibrating at different frequencies to induce a low frequency traveling wave have not been explored. Insomnia affects millions of people worldwide, and non-pharmacological treatment options are limited. A bed excited with multiple vibration sources was used to explore beat frequency vibration as a non-pharmacological treatment for insomnia. A repeated measures design pilot study of 14 participants with mild-moderate insomnia symptom severity was conducted to determine the effects of beat frequency vibration, and traditional standing wave vibration on sleep latency and quality. Participants were monitored using high-density electroencephalography (HD-EEG). Sleep latency was compared between treatment conditions. Trends of a decrease in sleep latency due to beat frequency vibration were found (p ≤ 0.181 for AASM latency, and p ≤ 0.068 for unequivocal sleep latency). Neural complexity during wake, N1, and N2 stages were compared using Multi-Scale Sample Entropy (MSE), which demonstrated significantly lower MSE between wake and N2 stages (p ≤ 0.002). Lower MSE was found in the transition from wake to N1 stage sleep but did not reach significance (p ≤ 0.300). During N2 sleep, beat frequency vibration shows lower MSE than the control session in the left frontoparietal region. This indicates that beat frequency vibration may lead to a decrease of conscious awareness during deeper stages of sleep. Standing wave vibration caused reduced Alpha activity and increased Delta activity during wake. Beat frequency vibration caused increased Delta activity during N2 sleep. These preliminary results suggest that beat frequency vibration may help individuals with insomnia symptoms by decreasing sleep latency, by reducing their conscious awareness, and by increasing sleep drive expression during deeper stages of sleep. Standing wave vibration may be beneficial for decreasing expression of arousal and increasing expression of sleep drive during wake, implying that a dynamic vibration treatment may be beneficial. The application of vibration treatment as part of a heuristic sleep model is discussed.
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Chan, Alfred. "Vocal fold vibration measurements using laser Doppler vibrometry." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106574.
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The objective of this study was to measure the velocity of the superior surface of human vocal folds during phonation using laser Doppler vibrometry (LDV). A custom-made endoscopic laser beam deflection unit was designed and fabricated. An in vivo clinical experimental procedure was developed and performed at the Montreal General Hospital Voice Laboratory in order to simultaneously collect velocity data from the LDV and video from endoscopy. The velocity along the direction of the laser beam, ie. the inferior-superior direction, was captured and found to be synchronous with electroglottograph (EGG) and sound level meter data. Recorded phonation onset/offset times were found to be commensurate with reported data obtained using EGG and high-speed imaging. The vibration energy of the vocal folds was determined to be significant up to a frequency of 3 kHz. The velocity amplitude was found to be approximately 45 mm/s and was consistent between subjects. A sparse map of the vocal fold surface velocity was obtained, which showed that the velocity amplitude did not change significantly with location. Different characteristic vibration waveforms were identified and attributed to the presence of a mucosal wave over the vocal fold surface. Laser Doppler vibrometry offers potential as a diagnostic tool for the early detection of vocal disorders. It may provide online biofeedback for voice professionals, and help them to tune their laryngeal tension to obtain the desired voice output.La présente étude avait pour but de mesurer directement la vitesse des cordes vocales de la voix humaine en utilisant la vibrométrie laser (VL). Une buse endoscopique pour la re-direction du faisceau laser a été conçue et construite. Un protocole expérimental de mesures en clinique a été développé et mis en oeuvre afin d'obtenir des signaux de vitesse simultanément avec des images vidéoendoscopiques. Les mesures furent prises au laboratoire de la voix de l'Hôpital Général de Montréal. La vitesse mesurée est dans l'axe du faisceau laser, soit dans la direction inférieure-supérieure. Des signaux synchrones provenant d'un électroglottogramme (EGG) et d'un microphone furent recueillis pour fins de comparaisons et de vérifications. Les signaux provenant du VL sont parfaitement corrélés et consistants avec les signaux du EGG et microphone ainsi que les informations provenant du vidéo. L'énergie vibratoire semble être présente dans un bande de fréquence allant jusqu'à 3 kHz. La vitesse est de 45 mm/s dans les trois cas étudiés, pour toute fréquence, amplitude et position. Différents modes vibratoires avec des formes d'ondes distinctes furent identifiés, probablement dus à la propagation d'ondes sur la surface supérieure des cordes vocales. Les résultats suggèrent que l'utilisation du VL pourrait mener à des applications intéressantes pour la détection de problèmes tels que des lésions. La VL pourrait aussi sans doute fournir une rétroaction à des professionnels de la voix qui leur permettrait d'ajuster la tension et la position de leur cordes vocales afin d'obtenir le timbre ou l'intonation désirée.
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Jackson, Stephen. "Proposed pixel for custom laser Doppler vibrometry camera." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12975/.
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Non-destructive testing is an important field of research in many areas of industry and science. This field covers methods that test some property of an object while not impacting its future usefulness. This project is specifically interested in a method of NDE called Laser Doppler Vibrometry (LDV), which uses light to probe the motion of an object's surface. This thesis presents research into the possibility of developing a full-field LDV camera capable of measuring the vibration at a number of points across an object simultaneously. The approach chosen was to develop a single processing element which contained a light detector as well as the processing required to produce an output signal proportional to the vibration of the surface imaged by the element. This processing element, or pixel, could then be used to produce a full-field LDV camera capable of imaging an object's surface to provide vibration amplitude and frequency for a number of points across the whole surface simultaneously Some early work was carried out measuring the vibration of a piezoelectric target with a CMOS camera and the results were compared with theory. The method of processing chosen is called zero-crossing demodulation and a circuit was designed and simulated using this method. This circuit was then laid-out and a CMOS chip was fabricated with the pixel on it. The circuit was designed such that the different parts of it could be tested separately using electrical signals, and a number of electrical tests were performed to check how well the operation of the fabricated pixel compared with simulation. Using a laser interferometer the pixel was finally tested with real vibrating objects and compared with a commercial LDV.
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Abel, Jeffry J. "Three-dimensional velocity extraction using laser Doppler vibrometry." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-12042009-020059/.
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Halkon, Benjamin John. "Laser Doppler vibrometry for vibration measurements on rotating structures." Thesis, Loughborough University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414974.
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Pan, Jingyi. "Confocal scanning laser tomography and scanning laser Doppler flowmetery in the rat eye." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ49422.pdf.
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Martin, Peter. "Uncertainty due to speckle noise in laser vibrometry." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/7139.
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This thesis presents fundamental research in the field of laser vibrometry for the application to vibration measurements. A key concern for laser vibrometry is the effect of laser speckle which appears when a coherent laser beam scatters from an optically rough surface. The laser vibrometer is sensitive to changes in laser speckle which result from surface motions not in the direction of the incident beam. This adds speckle noise to the vibrometer output which can be indistinguishable from the genuine surface vibrations. This has been termed ‘pseudo-vibration' and requires careful data interpretation by the vibration engineer. This research has discovered that measurements from smooth surfaces, even when no identifiable speckle pattern is generated, can produce noise and therefore reference to speckle noise, in such circumstances, is inappropriate. This thesis has, therefore, adopted the more general term of pseudo-vibration to include noise generated from any surface roughness or treatment, i.e. including but not limited to speckle noise. This thesis develops and implements novel experimental methods to quantify pseudovibration sensitivities (transverse, tilt and rotation sensitivity) with attention focussed on commercially available laser vibrometers and consideration is given to a range of surface roughnesses and treatments. It investigates, experimentally, the fundamental behaviour of speckles and attempts to formulate, for the first time, a relationship between changes in intensity to pseudo-vibration sensitivity levels. The thesis also develops and implements models for computational simulation of pseudo-vibrations using the fundamental behaviour of speckles. The combination of experimentation and simulation improves current understanding of the pseudo-vibration mechanisms and provides the vibration engineer with a valuable resource to improve data interpretation. Two experimental methods of quantifying pseudo-vibration sensitivity are developed and successfully applied in the evaluation of transverse, tilt and rotation sensitivity for two models of commercial laser vibrometer. These evaluations cover both single beam (translational vibration measurement) and parallel beam (for angular vibration measurement) modes. The first method presented requires correction of the vibrometer measurement with an independent measurement of genuine velocity to produce an iii apparent velocity dominated by the required noise components. The second method requires a differential measurement using two vibrometers to cancel common components such as genuine velocity, leaving only uncorrelated noise from each measurement in the resulting apparent velocity. In each case, a third measurement is required of the surface motion component causing pseudo-vibration and this is used to normalise the apparent velocity. Pseudo-vibration sensitivity is then presented as a map showing the spectral shape of the noise, as a mean and standard deviation of harmonic peaks in the map and as a total rms level across a defined bandwidth. The simulations employ a novel and effective approach to modelling speckle evolution. Transverse and tilt sensitivity are predicted for the first time and are verified by the experimental study. They provide the vibration engineer with the potential to estimate pseudo-vibrations using a simple piece of software. The laser beam spot diameter has a large influence on the pseudo-vibration sensitivity. Transverse sensitivity has been quantified as around 0.03% and 0.01% (per order) of the transverse velocity of the surface for beam spot diameters of 100 μm and 600 μm respectively. Larger beam spots have been shown to significantly reduce transverse sensitivity and measurements from smoother surfaces have also shown a reduced level of transverse sensitivity. Tilt sensitivity has been quantified at about 0.1 μms-1/degs-1 and 0.3 μms-1/degs-1 (per order) of angular velocity of the surface for beam spot diameters of 100 μm and 600 μm respectively. Smaller beam spot diameters significantly reduce tilt sensitivity. The surface roughness or treatment has been shown to have little effect on the level of tilt sensitivity. Rotation sensitivity has been quantified at approximately 0.6 μms- 1/rads-1 and 1.9μms-1/rads-1 (per order) of rotation velocity of the rotor for 90 μm and 520 μm. Smaller beam spot diameters have shown a significant reduction in rotation sensitivity and measurements on smoother surfaces have shown a reduced rotation sensitivity. Focussing the laser beam approximately on the rotation axis has also shown a significant reduction in rotation sensitivity. Parallel beam rotation sensitivity has been quantified at 0.016 degs-1/rads-1 and it is demonstrated that this can adequately be estimated using the single beam rotation sensitivity.
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Donovan, Joseph Brian. "Three-dimensional vibrometry via three positions of a one-dimensional laser doppler velocimeter." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-08142009-040347/.
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Olsson, Andreas. "Target recognition by vibrometry with a coherent laser radar." Thesis, Linköping University, Department of Electrical Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1730.
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Laser vibration sensing can be used to classify military targets by its unique vibration signature. A coherent laser radar receives the target´s rapidly oscillating surface vibrations and by using proper demodulation and Doppler technique, stationary, radially moving and even accelerating targets can be taken care of.
A frequency demodulation method developed at the former FOA, is for the first time validated against real data with turbulence, scattering, rain etc. The issue is to find a robust and reliable system for target recognition and its performance is therefore compared with some frequency distribution methods. The time frequency distributions have got a crucial drawback, they are affected by interference between the frequency and amplitude modulated multicomponent signals. The system requirements are believed to be fulfilled by combining the FOA method with the new statistical method proposed here, the combination being suggested as aimpoint for future investigations.
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Townsend, Russell James. "Experimental study of a scanning laser doppler flowmeter." University of Western Australia. Centre for Ophthalmology and Visual Science, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0063.
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[Truncated abstract] Purpose: To improve our ability to interpret and validate Heidelberg Retina Flowmeter (HRF) flow images by recording flow measurements from specific regions of the retinal vasculature in in-vitro and in-vivo eye models in which retinal blood flow can be manipulated. Methods: The first experiments utilised an isolated perfused pig eyes perfused with a 50%/50% Krebs/RBC solution at known flow rates ranging from zero to 300 μl/min. After HRF image acquisition, the retinal vasculature was perfused with fluorescein isothiocyanate (FITC), for fluorescence microscopy. Using the standard HRF software and a 10×10 pixel measurement window, flow rates were measured from a retinal artery, vein, arteriole, venule, and the retinal capillary bed and a capillary-free-zone. The relationship between HRF measured flow and perfusion flow in the different measurement regions was determined. For the second study, HRF flow images were acquired at retinal sites in Brown Norway rats over a range of focus levels before and after cessation of retinal blood flow by laser-induced central retinal artery occlusion. Using the 10×10 pixel and 4×4 pixel measurement windows, HRF measured flow was performed in retinal artery, vein, arteriole, capillary and choroidal vessel locations. The relationship between HRF measured flow and focus depth was determined for each location before and after central retinal artery occlusion. At the conclusion of each experiment the effect of reduction of systemic blood pressure (by exsanguination) on HRF flow measurements in choroidal vessels and in locations without visible choroidal vessels was assessed. Finally, HRF flow measurements were acquired after euthanasia, to determine the HRF flow signal which was still present under zero biological flow conditions (the zerooffset). Results: In the isolated perfused pig eye experiments it was found that the HRF flow response varied according to vascular location. At zero perfusate flow, HRF flow was consistently greater than zero at all locations, averaging 171.9 ± 44.7 AU (n=97), representing background noise. Arteries and veins yielded the highest HRF measured flow values, but the relationship between HRF measured flow and perfusate flow was not linear. In arterioles the HRF flow was more linear over a broader range of perfusate flow rates but the peak flow signal was an order of magnitude smaller than that in arteries and veins. Both the linearity and magnitude of the flow signal in venules was less than that in arterioles.
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Antoine, Marc M. E. "A rapidly scanning three-velocity-component laser Doppler anemometer." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/104288.
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Sharma, Vinod K. "Laser doppler vibrometer for efficient structural health monitoring." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26708.
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Thesis (Ph.D)--Aerospace Engineering, Georgia Institute of Technology, 2009.Committee Chair: Hanagud, Sathya; Committee Member: Apetre, Nicole; Committee Member: Engelstad, Steve; Committee Member: Glass, Brian; Committee Member: Kardomateas, George; Committee Member: Ruzzene, Massimo. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Willis, Richard Lance. "Non-invasive characterization of microvoided polymers under controlled static pressure and temperature using laser doppler vibrometry." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/17248.
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Acharya, Dabit. "COMPARATIVE EXPERIMENTAL STUDIES FOR GLOBAL DAMAGE DETECTION IN PLATES USING THE SCANNING LASER VIBROMETER TECHNIQUES." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1155079600.
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Li, Xinzuo William. "A precision laser scanning system for experimental modal analysis : its test and calibration /." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-08222009-040335/.
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Pal, Istvan. "Computerunterstützte Analyse der retinalen Zirkulationsstörungen, insbesondere des Glaukoms auf Scanning-Laser-Doppler-Flowmetrie-Aufnahmen /." Berlin : Logos Verlag Berlin, 2004. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=010735751&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Rayanne, Pinto Costa. "Transition to turbulence within an eccentric stenosis geometry under steady flow using laser Doppler vibrometry for a non-Newtonian and Newtonian fluid." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1605627935635379.
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Essex, Timothy John Hudson. "The development and evaluation of a scanning laser Doppler instrument for imaging skin blood flow." Thesis, Northumbria University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357147.
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Shinpaugh, Kevin A. "Design of a 3-D rapidly scanning laser Doppler velocimeter with low SNR signal processing." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/50092.
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A rapidly scanning directionally sensitive three-velocity-component laser Doppler velocimeter (RSLDV) has been designed. It permits scans through three-dimensional flows to obtain space-time velocity information and almost "instantaneous" velocity profiles vital to understanding such flows.
A flexible optical system allows for easy variation of the fringe spacing as well as the location and size of the measurement volume. Several optical techniques to maintain coincidence between the horizontal, U and W, and vertical, V, probe volumes were investigated. A lens, used like a prism, and two plane mirrors for the out of plane scanning laser beam maintains good coincidence between the probe volumes, while maintaining some flexibility. Moving fringe patterns in the horizontal and vertical planes are produced by two solid state Bragg cells. The Doppler frequency is independent of the position of the receiving optics, and only one photomultiplier tube (PMT) is needed to receive the signals for all three velocity components.
A data acquisition, control and processing system has also been designed for use with the RSLDV. The PMT signal and location of the measurement volume are recorded simultaneously by two transient recorders. The system provides storage for up to 1.25 gigabytes (6 secs.) of LDV data, with permanent storage onto optical disk. A 20 MFLOP array processor provides for fast computation of velocity information.
The Pisarenko harmonic decomposition (PHD) and fast Fourier transform (FFT) algorithms, with various interpolation techniques, were investigated for processing low signal-to-noise ratio signals for use with the RSLDV. The PHD algorithm was found to be unsuitable for use with processing RSLDV signals, however, the algorithm does provide superior frequency estimation for some frequency ratios at SNR levels above 30 dB, which are typical quality signals required for frequency counters. The FFT with zero-padding and log parabolic fit provides frequency estimates with RMS error below 1 % for signals with SNR above -5 dB. To obtain frequency estimates for signals with SNR below -5 dB, the FFT with zero-padding and parabolic lit must be used, signals with SNR down to -18 dB can be processed with this technique.Master of Science
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Li, Jingxuan. "Development of novel diagnostic techniques to measure heat release rate perturbations in flames." Phd thesis, Ecole Centrale Paris, 2012. http://tel.archives-ouvertes.fr/tel-00997413.
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Heat release rate disturbances are the sources of additional thermal stresses, direct and indirect combustion noise and undesirable vibrations. In extreme cases, these perturbations may even cause destructive combustion instabilities. These quantities are difficult to measure in practical burners. The objective of this work is to develop two alternative diagnostics to measure heat release rate fluctuations in unsteady flames. These techniques are validated in generic configurations for perfectly premixed laminar flames. The first method is an acoustic technique, which is based on the measurement of the travel time of ultrasonic waves through the flames. Fluctuations of the sound propagation time transmission through unsteady flames are used to estimate perturbations in the burned gases width along the acoustic path. This information is then used to reconstruct heat release rate fluctuations. This technique is validated in the cases of unstable laminar premixed flames driven by buoyancy forces and for flames submitted to harmonic flow velocity modulations. Analytical expressions are derived linking fluctuations in heat release rate and disturbances of the sound travel time. Measurements made with this acoustic technique are compared with optical detections based on the flame chemiluminescence and with predictions from an analytical model. Good agreements are obtained between these different methods validating the proposed technique. The second method envisaged is an optical technique based on a Laser Interferometric Vibrometer used to measure integrated density perturbations along the optical path of a laser beam. It is shown that density disturbances along this path result mainly from heat release rate fluctuations when the flames are confined. A link is established to reconstruct heat release rate disturbances from the signal of the interferometer. The technique is validated in the case of pulsated laminar premixed flames. Measurements are compared to line-of-sight integrated chemiluminescence emission measurements. A good agreement is obtained for harmonic flow modulations at different forcing frequencies and perturbation levels for flames operating at different flow conditions. This work validates the principle of this alternative technique for detecting heat release rate perturbations.
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Kil, Hyun-Gwon. "An automated scanning laser doppler system for vibration measurements and wave-vector analysis of vibration of shells." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/16856.
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Shinpaugh, Kevin A. "Measurements in the bimodal region of a wing-body junction flow with a rapidly-scanning two-velocity-component laser-Doppler velocimeter." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-163435/.
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Lam, Norris. "Modeling rating curves from close-range remote sensing data : Application of laser and acoustic ranging instruments for capturing stream channel topography." Doctoral thesis, Stockholms universitet, Institutionen för naturgeografi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-142135.
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A rating curve provides a functional relationship between water height (i.e. stage) and discharge at a specified cross-section in a river. Used in combination with a time series of stage, rating curves become one of the central components for generating continuous records of streamflow. Since developing and maintaining rating curves can be time consuming, hydraulic models have shown potential to reduce the effort required for developing rating curves. A central challenge with modeling procedures, however, is the acquisition of accurate stream channel and floodplain topography. From this perspective, this thesis focuses on the real-world application of close-range remote sensing techniques such as laser-based ranging technologies (i.e. Light detection and ranging or LiDAR) or acoustic based ranging technologies (i.e. acoustic Doppler current profiler or ADCP) to capture topographic information for hydraulic modeling applications across various spatial scales. First, a review of the current LiDAR literature was carried out to identify potential ways to take full advantage of these novel data and technologies in the future. This was followed by four interconnected studies whereby: (i) a low-cost custom laser scanning system was designed to capture grain size distributions for a small stream; (ii) synthetically thinned airborne laser scanning (ALS) data was applied in a physically-based hydraulic modelling framework to develop rating curves; (iii) low-resolution national-scale ALS was coupled with ADCP bathymetry to be used in conjunction with a hydraulic model to develop rating curves; and (iv) the impact of measurement uncertainties on generating rating curves with a hydraulic model were investigated. This thesis highlights the potential of close-range remote sensing techniques for capturing accurate stream channel topography and derive from these data, the necessary parameters required for hydraulic modeling applications.En avbördningskurva tillhandahåller ett funktionellt förhållande mellan vattendjup (dvs. vattenstånd) och flöde vid ett specifikt tvärsnitt i ett vattendrag. Avbördningskurvan blir en central komponent för generering av kontinuerliga tidsserier av vattenföring från tidsserier av vattenstånd. Eftersom det är tidskrävande att utveckla och underhålla avbördningskurvor erbjuder hydrauliska modeller attraktiva möjligheter att minska den insats som krävs för att utveckla avbördningskurvorna. En central utmaning för sådana modelleringsförfaranden är emellertid tillgången till noggrann topografidata av strömfåran och de omgivande stränderna. Den här avhandlingen fokuserar på tillämpningen av fjärranalystekniker för avståndsmätning på nära håll, såsom laserbaserade teknik (dvs. Light detection and ranging eller LiDAR) och akustisk baserat teknik (dvs. acoustic Doppler current profiler eller ADCP), för att fånga topografisk information för hydraulisk modellering av vattendrag i olika rumsliga skalor. Först presenteras en litteraturstudie av den nuvarande LiDAR-litteratur för att identifiera potentiella sätt att dra full nytta av dessa nya data och tekniker i framtiden. Detta följs av fyra sammanlänkade studier: (i) tillämpning av ett lågkostnads-laseravsökningssystem för att fånga kornstorleksfördelningar i ett litet vattendrag, (ii) syntetiskt förtunnad flygburen laserskanningsdata (ALS) applicerad i en fysiskt baserad hydraulisk modell för att utveckla avbördningskurvor, (iii) lågupplösta ALS från Svensk nationell höjdmodell kopplade med ADCP-batymetri för att ta fram en avbördningskurva med en hydraulisk modell, och (iv) undersökning av effekterna av osäkerheter på mätdata för att generera avbördningskurvor med en hydraulisk modell. Denna avhandling belyser potentialen för fjärranalystekniker för avståndsmätning på nära håll, för att fånga strömfårans exakta topografi och ifrån dessa data härleda de parametrar som krävs för hydrauliska modelleringstillämpningar.
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 5: Manuscript.
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Shaporin, Alexey. "Dynamic parameter identification techniques and test structures for microsystems characterization on wafer level." Doctoral thesis, Universitätsbibliothek Chemnitz, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200901902.
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In der vorliegenden Arbeit wird eine Methode zur Charakterisierung von Mikrosystemen mit beweglichen Komponenten dargestellt. Sie erlaubt, funktionsrelevante Parameter und deren Schwankungen produktionsbegleitend auf Waferlevel zu ermitteln. Dabei wird vorausgesetzt, dass die Sollform der Struktur und die Abweichungsarten bekannt sind. Die Methode beruht auf dem Vergleich von numerisch berechneten mit experimentell ermittelten Eigenfrequenzen der untersuchten Mikrosysteme. Dazu wird die Abhängigkeit verschiedener Eigenfrequenzen von den gesuchten Parametern mittels einer Parametervariationsanalyse berechnet und durch eine geeignete Funktion angenähert. Die Messung der dynamischen Eigenschaften erfolgt mit Hilfe eines Bewegungsanalysators, der auf einem Laser-Doppler-Vibrometer basiert. Im letzen Schritt werden die gesuchten Parameter berechnet. Kernpunkt der entwickelten Methode sind Messungen auf der Basis von speziellen Teststrukturen, die im Waferlayout neben den eigentlichen Nutzstrukturen platziert sind und parallel mit den Nutzstrukturen prozessiert werden. Es werden Algorithmen zur Generierung des Designs der Teststrukturen und ihrer Platzierung im Waferlayout entwickelt. Dabei werden das Design der Nutzstruktur und deren funktionsrelevante Parameter, der technologische Ablauf und materialspezifische Kennwerte berücksichtigt. Im Ergebnis liegt eine Bibliothek von Standard-Teststrukturen vor, die für produktionsbegleitende Messungen sowie für die Übertragbarkeit der Ergebnisse geeignet sind. Außerdem werden allgemeingültige Richtlinien zur Durchführung der Messungen an den Standard-Teststrukturen abgeleitet. Das Messverfahren wurde an unterschiedlichen Mikrosystemen mit beweglichen Komponenten überprüft und zu einer allgemeinen Messmethode für diese Klasse von Mikrosystemen erweitertIn this work a method for the characterization of microsystems with movable components is presented. The method allows to determine the relevant parameters and their variations on wafer level if the nominal shape of the structure and the type of deviations are known. The method is based on a comparison of the numerically calculated and experimentally measured Eigenfrequencies of the microsystems. For that purpose, the relationships between various Eigenfrequencies and the searched parameters are calculated by parameter variation analysis and the results of this analysis are approximated with appropriate functions. A Laser Doppler vibrometer based motion analyzer is used to determine the frequency response function of the micromechanical structure and extract Eigenfrequencies. The comparison of the measured and the calculated frequencies provides values for the searched parameters. The key element of the developed method is the measurement on special test structures that are placed in the wafer layout next to the actual microsystems and processed in the same technological process parallel to the actual microsystems. Algorithms for designing the test structures and their placement in the wafer layout are shown, taking into account the design of the actual microsystems and the function parameters of the technological process as well as material characteristics. As a result, a library of standard test structures for function relevant parameters is available. A general guideline for the measurement on the test structures is presented. The presented method is verified on various microsystems and extended to a whole class of microsystems with movable components
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Stöckel, Chris. "Piezoelektrische Aluminiumnitrid-Dünnschichten für mikroelektromechanische Systeme." Doctoral thesis, Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-215293.
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In der vorliegenden Arbeit werden der Entwurf, die Technologie und die Parameteridentifikation von Silizium basierten mikroelektromechanischen Systemen (MEMS) mit piezoelektrischen Dünnschicht-Aluminiumnitrid (AlN) vorgestellt. Auf Basis des AlNs als elektromechanischer Wandler erfolgt die Fertigung eines MEMS Technologiedemonstrators für energiearme Inertialsensoren. Das AlN wird über einen reaktiven Sputterprozess auf einer Wachstumsschicht abgeschieden. Durch Parametervariation des reaktiven Sputterprozesses und der Wachstumsschicht werden die piezoelektrischen Eigenschaften des AlNs optimiert. Die Entwicklung einer Gesamttechnologie führt zu einer Integration des Dünnschicht-AlNs in Silizium-Mikromechaniken. Die Röntgenbeugung (XRD) ermöglicht die Kristallstruktur des AlNs zu qualifizieren. Darüber hinaus werden weitere Analysemethoden vorgestellt, die eine hoch genaue und reproduzierbare messtechnische Bestimmung der piezoelektrischen Koeffizienten aus mikromechanischen Messstrukturen ermöglichen. Die Determination der piezoelektrischen Koeffizienten des Dünnschicht-AlNs aus den Messstrukturen erfolgt mittels analytischen und FE Modellen sowie der Laser-Doppler-Vibrometrie (LDV). Der Fokus der Arbeit liegt hierbei auf der Identifikation der longitudinalen und transversalen piezoelektrischen Ladungskoeffizienten des AlNs. Als Technologiedemonstrator wird ein einachsiger Inertialsensor mit integriertem piezoelektrischen Dünnschicht-AlN vorgestellt. Das MEMS generiert aufgrund des piezoelektrischen Wandlers intrinsisch elektrische Ladungen bei Einwirkung einer mechanischen Energie. Dadurch ist keine elektrische Energiezufuhr für die Messung eines inertialen Ereignisses notwendig. Der vorgestellte Demonstrator wird hinsichtlich seiner Ladungs- und Spannungssensitivität optimiert. Zur theoretischen Beschreibung der Funktionsweise werden analytische, sowie FE und SPICE Modelle genutzt. Eine Charakterisierung des MEMS Bauelements erfolgt hinsichtlich der mechanischen und elektrischen EigenschaftenThe thesis includes the design, the technology and the parameter identification of silicon-based microelectromechanical systems (MEMS) with piezoelectric thin film of aluminum nitride (AlN). A low-energy inertial sensor as technology demonstrator based on AlN as an electromechanical transducer a MEMS manufacturing process is shown. The AlN is deposited via a reactive sputtering on a growth layer. By varying parameters of the reactive sputtering and the growth layer of AlN, the piezoelectric properties can be optimized. The development of an overall technology results to an integration of the thin film AlNs in silicon micromechanics. X-ray diffraction (XRD) allows to qualify the crystal structure of AlN. Further methods are developed that enable a highly accurate and repeatable metrological determination of piezoelectric coefficients measurement structures. The determination of piezoelectric coefficients of the thin film AlN from the measurement structures is resulting from analytical methods and FE models and the laser Doppler vibrometry (LDV). The identification of the longitudinal and transverse piezoelectric charge coefficient of AlN is one main focus of this work. A uniaxial inertial sensor with an integrated piezoelectric thin film of AlN is presented as technology demonstrator. The piezoelectric transducer of the MEMS is generating electric charges intrinsically as reaction of mechanical stress. Thus, no electric power supply for the measurement of an inertial event is necessary. The presented demonstrator has been optimized with respect to its charge and voltage sensitivity. For a theoretical description analytical and FE and SPICE models are used. A characterization of the MEMS device is carried out with regard to the mechanical and electrical properties
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Cassidy, Scott L. "Millimetre-wave FMCW radar for remote sensing and security applications." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/7856.
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This thesis presents a body of work on the theme of millimetre-wave FMCW radar, for the purposes of security screening and remote sensing. First, the development of an optimised software radar signal processor will be outlined. Through use of threading and GPU acceleration, high data processing rates were achieved using standard PC hardware. The flexibility of this approach, compared to specialised hardware (e.g. DSP, FPGA etc…), allowed the processor to be rapidly adapted and has produced a significant performance increase in a number of advanced real-time radar systems. An efficient tracker was developed and was successfully deployed in live trials for the purpose of real-time wave detection in an autonomous boat control system. Automated radar operation and remote data telemetry functions were implemented in a terrain mapping radar to allow continuous monitoring of the Soufrière Hills volcano on the Caribbean island of Montserrat. This work concluded with the installation of the system 3 km from the volcano. Hardware modifications were made to enable coherent measurement in a number of existing radar systems, allowing phase sensitive measurements, including range-Doppler, to be performed. Sensitivity to displacements of less than 200 nm was demonstrated, which is limited by the phase noise of the system. Efficient compensation techniques are presented which correct for quadrature mixer imbalance, FMCW chirp non-linearity, and scanner drive distortions. In collaboration with the Home Office, two radar systems were evaluated for the stand-off detection of concealed objects. Automatic detection capability, based on polarimetric signatures, was developed using data gathered under controlled conditions. Algorithm performance was assessed through blind testing across a statistically significant number of subjects. A detailed analysis is presented, which evaluates the effect of clothing and object type on detection efficiency.
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Shaporin, Alexey. "Dynamic parameter identification techniques and test structures for microsystems characterization on wafer level." Doctoral thesis, Chemnitz Univ.-Verl, 2009. http://d-nb.info/1000815250/04.
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Wildy, Stuart James. "Scanning laser doppler vibrometry for strain measurement and damage detection." Thesis, 2012. http://hdl.handle.net/2440/93519.
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Numerous strain measurement and damage detection techniques have been developed over the last century. These techniques include strain gauges, digital image correlation, radiography and ultrasonic inspections. All have various advantages, as well as disadvantages, which make each suited to specific applications. With the development of laser Doppler vibrometry, a number of techniques have been established for non-destructive evaluation, such as the measurement of bending strain, as well as damage detection using kinematic parameters, including displacement and curvature. With recent advancements in laser Doppler vibrometry technology (such as 3D scanning laser Doppler vibrometry for three-dimensional displacement measurements, improved velocity decoders and increased spatial resolution) the door has been opened to develop techniques for measuring surface strain from in-plane displacements, as well as the development of new damage detection techniques based on the fundamental principle of deformation:- the governing differential equation of displacement. The extensive literature review contained in this thesis identified a number of gaps in the field, including the evaluation of the accuracy of quasi-static bending strain measurements using current 1D SLDV technology, the precision of full-field surface strain measurement techniques utilising 3D SLDV, and new detection techniques based on the violation of the governing differential equations of displacement. Thus, the research contained in this thesis focussed on these areas. The first part of this thesis presents an investigation into the use of 1D and 3D scanning laser Doppler vibrometry for non-contact measurement of quasi-static bending strain in beams and surface strain in plates, respectively. The second part presents a new damage detection technique based on the governing differential equations of displacement in beam and plate structures. Two algorithms are developed to determine a violation in the governing differential equations created by either a delamination in a composite beam with out-of-plane displacements, or by a crack in a plate with in-plane displacements.Thesis (Ph.D.) -- University of Adelaide, School of Mechanical Engineering, 2012
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Venkatesh, Kadbur Prabhakar Rao. "Experimental Studies on Extremely Small Scale Vibrations of Micro-Scale Mechanical and Biological Structures." Thesis, 2017. http://etd.iisc.ernet.in/2005/3541.
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Experimental vibration analysis of mechanical structures is a well established field.Plenty of literature exists on macro scale structures in the fields of civil, mechanical and aerospace engineering, but the study of vibrations of micro scale structures such as MEMS, liquid droplets, and biological cells is relatively new. For such structures, the amplitudes of vibration are typically in nanometeror sub-nanometer range and the frequencies are in KHz to MHz range depending upon the dimensions of the structure. In our study, we use a scanningLaser Doppler Vibrometer (LDV) to measure the vibrations of micro-scale objects such as MEMS structures, micro droplets and cells. The vibrometercan capture frequency response up to 24 MHz withpicometer displacement resolution.
First, we present the study of dynamics of a 2-D micromechanical structure—a MEMSelectrothermal actuator. The structure is realized using SOI MUMPs process from MEMSCAP. The fabricated device is tested for its dynamic performance characteristics using the LDV. In our experiments, we could capture up to 50 out-of-plane modes of vibration—an unprecedented capture—with a single excitation. Subsequent FEM based numerical simulations confirmed that the captured modes were indeed what the experiments indicated, and the measured frequencies werefound to be within 5% of theoretically predicted. Next, we study the dynamics of a 3-D micro droplet and show how the substrate adhesion modulates the natural frequency of the droplet. Adhesion properties of droplets are decided by the degree of wettability that is generally measured by the contact angle between the substrate and the droplet. In this work, we were able to capture 14 modes of vibration of a mercury droplet on different substrates and measure the correspondingfrequencies experimentally. We verify these frequencies with analytical calculations and find that all the measured frequencies are within 6% of theoretically predicted values. We also show that considering any two pairs of natural frequencies, we can calculate the surface tension and the contact angle, thus providing a new method for measuring adhesion of a droplet on an unknown surface. Lastly, we present a study of vibrations of biological cells.Our first study is that of single muscle fibers taken from drosophila.Muscle fibers with different pathological conditions were held in two structural configurations—asa fixed-fixed beam and a cantilever beam—and their vibration signatures analysed.We found that there was significant reduction in natural frequency of diseased fibers. Among the diseased fibers, we could confidently classify the myopathies into nemaline and cardiac types based on the natural frequency of single fibers. We have noticed that the elastic modulus of the muscle which decides the natural frequency is dictated by the myosin expression levels. Our last example isa study of the vibration signatures of cancer cells. Here we measure the natural frequencies of normal and certain cancerous cells, and show that we can distinguish the two based on their natural frequencies. We find that the natural frequency of cancerous cells is approximately half of that of normal cells. Within the cancerous cells, we are able to distinguished epithelial cancer cells and mesenchymal cancer cells based on their natural frequency values. For Epithelial cells,we activate the signaling pathways to induce EMT and notice the reduction in the natural frequency. This mechanical assay based on vibration response corroborates results from the biochemical assays such as Western blots and PCR, thus opening a new technique of mechano-diagnostics.
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Oberholster, Abraham Johannes. "The application of Eulerian laser Doppler vibrometry to the on-line condition monitoring of axial-flow turbomachinery blades." Thesis, 2010. http://hdl.handle.net/2263/25794.
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The on-line condition monitoring of turbomachinery blades is of utmost importance to ensure the long term health and availability of such machines and as such has been an area of study since the late 1960s. As a result a number of on-line blade vibration measurement techniques are available, each with its own associated advantages and shortcomings. In general, on-blade sensor measurement techniques suffer from sensor lifespan, whereas non-contact techniques usually have measurement bandwidth limitations. One non-contact measurement technique that yields improvements in the area of measurement bandwidth is laser Doppler vibrometry. This thesis presents results and findings from utilizing laser Doppler vibrometry in an Eulerian fashion (i.e. a fixed reference frame) to measure on-line blade vibrations in axial-flow turbomachinery. With this measurement approach, the laser beam is focussed at a fixed point in space and measurements are available for the periods during which each blade sweeps through the beam. The characteristics of the measurement technique are studied analytically with an Euler-Bernoulli cantilever beam and experimental verification is performed. An approach for the numerical simulation of the measurement technique is then presented. Associated with the presented measurement technique are the short periods during which each blade is exposed to the laser beam. This characteristic yields traditional frequency domain signal processing techniques unsuitable for providing useful blade health indicators. To obtain frequency domain information from such short signals, it is necessary to employ non-standard signal processing techniques such as non-harmonic Fourier analysis. Results from experimental testing on a single-blade test rotor at a single rotor speed are presented in the form of phase angle trends obtained with non-harmonic Fourier analysis. Considering the maximum of absolute unwrapped phase angle trends around various reference frequencies, good indicators of blade health deterioration were obtained. These indicators were verified numerically. To extend the application of this condition monitoring approach, measurements were repeated on a five-blade test rotor at four different rotor speeds. Various damage cases were considered as well as different ELDV measurement positions. Using statistical parameters of the abovementioned indicators as well as time domain parameters, it is shown that with this condition monitoring approach, blade damage can successfully be identified and quantified with the aid of artificial neural networks.Thesis (PhD)--University of Pretoria, 2010.
Mechanical and Aeronautical Engineering
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Hartmann, Michael [Verfasser]. "Intraoperative Messung der zerebralen Mikrozirkulation mittels Laser-Doppler-Scanning-Imager / vorgelegt von Michael Hartmann." 2005. http://d-nb.info/976744155/34.
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