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1
Larson, Gregg D. "The analysis and realization of a state switched acoustic transducer". Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/16008.
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Liu, Qingli 1973. "Development and application of integrated and flexible transducers". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116018.
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Health monitoring of aeronautic structures and human beings is becoming crucial because of the human safety issues. In this thesis integrated (IUTs) and flexible ultrasonic transducers (FUTs) have been developed using a sol-gel spray piezoelectric film fabrication technology. IUTs can be fabricated directly onto the structures with curved surfaces even on-site. FUTs were made using membrane substrates of thickness less than 75 mum. In-situ monitoring of AI airframe thickness was carried out and the thickness measurement accuracy was better than 36 mum and 41 mum for IUT and FUT, respectively. The thickness of the ice on top of the AI airframe was also measured. Two crucial piezoelectric constants d33 and d31 of the composite film were measured with laser interferometer and optical coherence tomography system, respectively. Pulse and breath of a human being were also monitored using flexible piezoelectric membrane sensors. In addition, bones in human body were observed using FUTs as well and their performance is comparable to that of commercial ultrasonic transducers.
3
Sivapurapu, Abhishek. "Piezoelectrically-Transduced Silicon Micromechanical Resonators". Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7478.
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This thesis reports on the design and fabrication of micro-electro-mechanical (MEM) resonators on silicon that are piezoelectrically-transduced for operation in the very high frequency (VHF) range. These devices have a block-type or beam-type design, and are designed to resonate in their in-plane and out-of-plane bulk extensional modes. Two piezoelectric materials were taken into consideration, zinc-oxide (ZnO) and lead-zirconate-titanate (PZT). The resonators are fabricated on silicon-on-insulator (SOI) wafers and the metal/piezo/metal stack of layers forming the device is built and patterned on the device layer silicon via photolithography techniques, RF sputtering (for the piezo-layer) and electron-beam evaporation (for the metal layers). The designing aspect involved ANSYS simulations of the mode-shapes and estimation of frequencies, and these have correlated well with experimental results. Devices with RF sputtered ZnO were successfully fabricated and tested to give high quality factors at reasonably high frequencies. A gold ground plane was implemented to reduce the feed-through level and increase the signal-to-noise ratio. Extensive characterization of PZT was also done as a replacement for ZnO, as the former material has a much higher piezoelectric coefficient (~20X that of ZnO) and can therefore extend the operation of these MEM resonators into the UHF range. Although the basic design of the device remains the same, incorporation of PZT complicates the process flow considerably with respect to the chemistry now involved with the patterning of different layers. The frequency response for ZnO-based resonators as well as all the characterization data for PZT has been reported.
4
Hayward, Gordon. "Modelling and design of 1-3 piezoelectric composite transducers". Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366880.
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Qin, Lei. "Development and application of cement-based piezoelectric composite in concrete behavior monitoring /". View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202008%20QIN.
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O'Leary, Richard Lewis. "An investigation into the passive materials utilised within the construction of piezoelectric composite transducers". Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405537.
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Devaraju, Vadivel Lewin Peter A. "Design, development and characterization of wideband polymer ultrasonic probes for medical ultrasound applications /". Philadelphia : Drexel University, 2003. http://dspace.library.drexel.edu/handle/1721.1/95.
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Fu, Yao y n/a. "Design of a hybrid magnetic and piezoelectric polymer microactuator". Swinburne University of Technology. Industrial Research Institute Swinburne, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20060712.141636.
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Microsensors and microactuators are considered to be the most crucial elements
of micro-electromechanical systems (MEMS) and devices. There has been growing interest
in the development of new microactuator technologies with an increasing requirement
for low cost microswitch arrays providing large air gap and large force at the
same time. In particular, large air gap/large force microactuators are essential for high
voltage switching in automobile electronics, test equipment switchboards and in network
remote reconfiguration. The necessity to reduce the size of actuators and at the
same time increase the force and the air gap has placed severe constraints on the suitability
of current microactuator technology for various applications. This has led to the
development of new actuator technologies based on novel materials or modifying existing
systems. As an effort in this direction, this thesis presents the details of the work on
the design, fabrication and testing of a new hybrid microactuator, combining electromagnetic
and piezoelectric actuation mechanisms.
The design and fabrication of electromagnetic actuators using planar coils and a
soft magnetic core has long been established. However, in many instances these designs
are constrained by difficulties in the fabrication of the multi layer planar coils, which is
tedious, often resulting in a low yield. Hence device performance is limited by the
maximum coil currents and thereby the maximum force able to be generated. In order to
overcome these problems, a hybrid actuator combining the electromagnetic system
along side of a piezoelectric actuation is proposed. This has been demonstrated to assist
in enhancing the total force and consequently achieving larger actuator displacements.
In this research a hybrid microactuator with a footprint of 10 mm2 was designed, fabricated
and tested. It can generate 330 쎠force and cover 100 쭠air gap as a microswitch.
Piezoelectric actuation has been used for many applications, due to its high precision
and speed. In these applications, piezo-ceramic materials, such as PZT and ZnO
were commonly used because they exhibit large piezoelectric coefficients. However,
there are also some difficulties associated with their use. Piezoelectric ceramic materials
are usually brittle, and have a relatively large Young?s modulus, thus limiting the
achievable strain. Furthermore, the deposition technologies required for preparing
thin/thick films of these ceramic materials need extensive optimization. Patterning these
films into required structures is also difficult. Hence, piezoelectric polymer polyvinylidene
fluoride (PVDF) is chosen in this work in spite of the fact that these materials
have relatively lower piezoelectric coefficients. However, the low numerical Young?s
modulus values of these polymers facilitates large strain in the piezoelectric actuators.
The hybrid microactuator designed in this work comprises a piezoelectric composite
polymer cantilever with a planar electromagnetic coil structure beneath. The
composite cantilever consists of polarized piezoelectric polymer PVDF with an electroplated
permalloy layer on one side. The device includes a permalloy core at the centre
of a copper micro coil with a permanent magnetic film attached on the other side of the
silicon wafer (substrate) and is aligned axially with the permalloy core. The cantilever is
suspended from an electroplated 150 mm high nickel post.
Initially the principle was tested using hand wound electromagnetic coils with
permalloy wire as the core. The performance of such a hybrid actuator was evaluated. In
the next stage, a microactuator was fabricated using completely planar micro technologies,
such as high aspect ratio SU-8 lithography, laser micromachining, microembossing,
as well as copper and permalloy electroplating.
This micro device was designed by modelling and finite element method simulation
using ANSYS 7.1 and CoventorWare electromagnetic and piezoelectric solvers respectively.
This helped in understanding the critical aspects of the design at the same
time leading to the determination of the optimum parameters for the cantilever, micro
coils and the core. An analytical model has also been developed to validate the numerical
results obtained from finite element analysis.
The devices were tested and the experimental data obtained were compared with
the simulation results obtained from both the finite element calculations and from the analytical model. Good agreement was found between the experimental results and the
simulation.
9
Hopkinson, David P. "Development of stress gradient enhanced piezoelectric composite unimorph actuators". Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/16372.
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McCray, Thomas Wade. "Construction and characterization of removable and reusable piezoelectric actuators". Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06232009-063342/.
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Jenne, Kirk E. "Acoustic cymbal transducers-design, hydrostatic pressure compensation, and acoustic performance". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FJenne.pdf.
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Thesis (M.S. in Engineering Acoustics)--Naval Postgraduate School, March 2004.Thesis advisor(s): Thomas R. Howarth, Dehua Huang. Includes bibliographical references (p. 67-69). Also available online.
12
Tuncdemir, Safakcan. "Design Of Mini Swimming Robot Using Piezoelectric Actuator". Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605682/index.pdf.
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This thesis deals with the design, fabrication and analysis of a novel actuator for a fish-like swimming mini robot. The developed actuator is tested on a mini boat. The
actuator relies on a novel piezoelectric ultrasonic motor, developed according to the design requirements of actuator for fish-like swimming mini robots. Developed motor is within the dimensions of 25x6x6 mm in a simple mechanical structure with simple driving circuitry compared to its predecessor. Bidirectional rotation of the motor is transformed to a flapping tail motion for underwater locomotion in a simple mechatronic structure. The simplicity in the motor and actuator enables
further development on the miniaturization, improvement on the performances as well as easy and low cost manufacturing. The developed actuator is a candidate to
be used in mini swimming robot with fish- like locomotion.
13
Pham, Thanh Tuong. "Design, Modeling, and Experiment of a Piezoelectric Pressure Sensor based on a Thickness-Shear Mode Crystal Resonator". Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984155/.
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This thesis presents the design, modeling, and experiment of a novel pressure sensor using a dual-mode AT-cut quartz crystal resonator with beat frequency analysis based temperature compensation technique. The proposed sensor can measure pressure and temperature simultaneously by a single AT-cut quartz resonator. Apart from AT-cut quartz crystal, a newly developed Langasite (LGS) crystal resonator is also considered in the proposed pressure sensor design, since LGS can operate in a higher temperature environment than AT-cut quartz crystal. The pressure sensor is designed using CAD (computer aided design) software and CAE software - COMSOL Multiphysics. Finite element analysis (FEA) of the pressure sensor is performed to analyze the stress- strain of the sensor's mechanical structure. A 3D printing prototype of the sensor is fabricated and the proposed sensing principle is verified using a force-frequency analysis apparatus. Next to the 3D printing model verification, the pressure sensor with stainless steel housing has been fabricated with inbuilt crystal oscillator circuit. The oscillator circuit is used to excite the piezo crystal resonator at its fundamental vibrational mode and give the frequency as an output signal. Based on the FEA and experimental results, it has been concluded that the maximum pressure that the sensor can measure is 45 (psi). The pressure test results performed on the stainless steel product shows a highly linear relationship between the input (pressure) and the output (frequency).
14
Oates, William Sumner. "Piezoelecytric pump design and system dynamic model". Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17679.
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McLean, Jeffrey John. "Interdigital Capacitive Micromachined Ultrasonic Transducers for Microfluidic Applications". Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7625.
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The goal of this research was to develop acoustic sensors and actuators for microfluidic applications. To this end, capacitive micromachined ultrasonic transducers (cMUTs) were developed which generate guided acoustic waves in fluid half-spaces and microchannels. An interdigital transducer structure and a phased excitation scheme were used to selectively excite guided acoustic modes which propagate in a single lateral direction. Analytical models were developed to predict the geometric dispersion of the acoustic modes and to determine the sensitivity of the modes to changes in material and geometric parameters. Coupled field finite element models were also developed to predict the effect of membrane spacing and phasing on mode generation and directionality.
After designing the transducers, a surface micromachining process was developed which has a low processing temperature of 250C and has the potential for monolithically integrating cMUTs with CMOS electronics. The fabrication process makes extensive use of PECVD silicon nitride depositions for membrane formation and sealing. The fabricated interdigital cMUTs were placed in microfluidic channels and demonstrated to sense changes in fluid sound speed and flow rate using Scholte waves and other guided acoustic modes. The minimum detectable change in sound speed was 0.25m/s, and the minimum detectable change in flow rate was 1mL/min. The unique nature of the Scholte wave allowed for the measurement of fluid properties of a semi-infinite fluid using two transducers on a single substrate. Changes in water temperature, and thus sound speed, were measured and the minimum detectable change in temperature was found to be 0.1C. For fluid pumping, interdigital cMUTs were integrated into microchannels and excited with phase-shifted, continuous wave signals. Highly directional guided waves were generated which in turn generated acoustic streaming forces in the fluid. The acoustic streaming forces caused the fluid to be pumped in a single, electronically-controlled direction. For a power consumption of 43mW, a flow rate of 410nL/min was generated against a pressure of 3.4Pa; the thermodynamic efficiency was approximately 5x10-8%. Although the efficiency and pressure head are low, these transducers can be useful for precisely manipulating small amounts of fluid around microfluidic networks.
16
Mauck, Lisa D. "The role of rate dependence and dissipation in the constitutive behavior of ferroelectric ceramics for high power applications". Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/15864.
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Ha, Kwangtae. "A Combined Piezoelectric Composite Actuator and Its Application to Wing/Blade Tips". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7575.
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A novel combined piezoelectric-composite actuator configuration is proposed and analytically modeled in this work. The actuator is a low complexity, active compliant mechanism obtained by coupling a modified star cross sectional configuration composite beam with a helicoidal bimorph piezoelectric actuator coiled around it. This novel actuator is a good candidate as a hinge tension-torsion bar actuator for a helicopter rotor blade flap or blade tip and mirror rotational positioning. In the wing tip case, the tip deflection angle is different only according to the aerodynamic moment depending on the hinge position of the actuator along the chord and applied voltage because there is no centrifugal force. For an active blade tip subject to incompressible flow and 2D quasi steady airloads, its twist angle is related not only to aerodynamic moment and applied voltage but also to coupling terms, such as the trapeze effect and the tennis racquet effect. Results show the benefit of hinge position aft of the aerodynamic center, such that the blade tip response is amplified by airloads. Contrary to this effect, results also show that the centrifugal effects and inertial effect cause an amplitude reduction in the response. Summation of these effects determines the overall blade tip response. The results for a certain hinge position of Xh=1.5% chord aft of the quarter chord point proves that the tip deflection target design range[-2,+2] can be achieved for all pitch angle configurations chosen.
18
Webber, Kyle Grant. "Characterization of Actuation and Fatigue Properties of Piezoelectric Composite Actuators". Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7127.
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Epoxy composite laminated piezoelectric stress-enhanced actuators (ECLIPSE) have been developed for potential applications by the United States Air Force and others. This class of actuators offers several advantages over other unimorph actuators such as lighter weight, design flexibility, and short production time. Anisotropic differential thermal expansion is utilized in the design of the actuators to achieve large out-of-plane curvature and place the brittle piezoelectric ceramic in residual compression. The numerous composite material choices and configurations can be used to control characteristics of the actuator such as radius of curvature and force output.
ECLIPSE actuators were characterized during this study. They were made from layers of Kevlar 49/epoxy composite and a lead zirconate titanate ceramic (PZT) plate. All ECLIPSE actuators tested were built with a PZT plate with the same dimensions and material, but had different layup configurations. By changing the stacking order of the composite and PZT material, characteristics of the actuator were altered. The performance of each ECLIPSE actuator was compared. The maximum achievable displacement of each actuator was measured by cyclically applying an electric field at low frequency between zero and the maximum electric field allowable for the piezoelectric material. The frequency was also increased to a resonance condition to characterize the fatigue behavior of these actuators. In addition, the force output of various actuators was measured with a four-point bending apparatus. The experimental data was compared to a classical lamination theory model and an extended classical lamination theory model. These models were used to predict actuator behavior as well as to calculate the stress and strain distribution through the thickness of the actuator.
19
Gao, Puxian. "Piezoelectric Nanostructures of Zinc Oxide: Synthesis, Characterization and Devices". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7564.
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In this thesis, a systematic study has been carried out on the synthesis, characterization and device fabrication of piezoelectric ZnO nanstructures. The achieved results are composed of the following four parts.
Firstly, through a systematic investigation on the Sn-catalyzed ZnO nanostructure, an improved understanding of the chemical and physical process occurring during the growth of hierarchical nanostructures has been achieved. Decomposed Sn from SnO2 has been successfully demonstrated and proved to be an effective catalyst guiding the growth of not only aligned ZnO nanowires, but also the hierarchical nanowire-nanoribbon junction arrays and nanopropeller arrays. During the vapor-liquid-solid (VLS) catalyzing growth process at high temperature, Sn in the liquid state has been proved to be able to guide the growth of nanowires and nanoribbons in terms of growth directions, side facets, and crystallographic interfaces between Sn and ZnO nanostructures.
Secondly, using pure ZnO as the only source material, by precisely tuning and controlling the growth kinetics, a variety of hierarchical polar surface dominated nanostructures have been achieved, such as single crystal nanorings, nanobows, nanosprings and superlattice nanohelices. High yield synthesis of ZnO nanosprings over 50% has been successfully obtained by mainly controlling the pre-pumping level associated with the partial pressure of residual oxygen during the vapor-solid growth process. The rigid superlattice nanohelices of ZnO have been discovered, which is a result of minimization of the electrostatic energy induced by polar surfaces. The formation process of the nanohelix has been systematically characterized.
Thirdly, two new strategies have been successfully developed for fabricating ZnO quantum dots and synthesis of ZnO nanodiskettes and nanotubes. The formation process is based on a common concept of self-assembly.
Finally, a series of devices and applications studies based on several piezoelectric ZnO nanostructures, such as nanobelts, nanopropellers and nanohelices, have been carried out utilizing the electro-mechanical resonance, bio-surface functionalization, devices fabrication and electrical characterization. Individual nanobelt and nanohelix based nanodevices have been successfully fabricated for applications in chemical and biological sensing. The study opens a few new areas in oxide nanostructures and applications.
20
Campbell, David Scott. "Design and calibration of a rapid-response thin-film heat flux gage". Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/104303.
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Paik, Seung Woock. "Simultaneous direct measurements of skin friction and heat flux in a supersonic flow". Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40116.
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Kharrat, Mohamed. "Design and development of a torsional guided-waves inspection system for the detection and sizing of defects in pipes". Thesis, Ecully, Ecole centrale de Lyon, 2012. http://www.theses.fr/2012ECDL0016/document.
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Plusieurs industries manipulent des substances liquides et gazeuses qui circulent souvent dans de longues canalisations. La technique d'ondes guidées est couramment utilisée dans ce domaine. Cette technique est en progrès continu. Dans cette thèse, un système d'inspection a été conçu et développé. Il est basé sur des transducteurs piézoélectriques qui génèrent des ondes guidées de torsion pouvant se propager le long du tube testé. Les signaux réfléchis des défauts et singularités rencontrés sont détectés aussi par des capteurs piézoélectriques. Des simulations numériques utilisantpar la méthode d'éléments finis standard et la méthode Wave Finite Element(WFEM) ont été effectuées afin de vérifier et de visualiser le phénomène de propagation des ondes dans des tubes intacts et endommagés. Un ensemble de tests a été mis en place sur des tubes droits et courbés avec deux matériaux différents: PVC et acier. L'interaction entre les ondes générées et les défauts usinés a été prouvée.Les résultats numériques et expérimentaux confirment certaines caractéristiques spécifiques concernant le coefficient de réflexion de l'onde. Par la suite, un pipeline industriel d'environ soixante mètres de long et contenant plusieurs défauts et singularités a été testé par le système d'inspection. Les signaux enregistrés ont soumis certains traitements numériques afin de les rendre exploitables. Les signaux traités sont analysés afin d'identifier et de distinguer les réflexions des défauts de celles des singularités structurés. La méthode WFEM a été employée pour construire une base de données numérique des coefficients de réflexion en variant la profondeur et les extensions axiale et circonférentielle du défaut modélisé. Le calcul a été établi en fonction de la fréquence. La corrélation des tailles des défauts est effectuée en balayant la base de données numérique pour trouver la combinaison appropriée de dimensions pour un défaut donné. Les réflexions à partir des singularités structurées (coudes, blocs de béton, colliers, et les soudures) sont traitées ainsi en comparant des coefficients de réflexion obtenus par WFEM à ceux évalués expérimentalement. Enfin, on a étudié numériquement l'effet de la position angulaire d'un défaut sur les coefficients de réflexion et de transmission tout en excitant à différents types d'ondes. La méthode WFE est aussi utilisée pour effectuer le calcul. Cette étude donne un guide à la localisation circonférentielle des défauts dans les tubesLong pipelines are widely used in several industries transporting liquid or gas. The guided wave technique is commonly used in this field and it is under continuing progress. In this thesis, an inspection system has been designed and developed. Piezoelectric transducers are employed to generate torsional guided waves that could propagate along the tested pipe; and receive reflected signals from encountered features and damages. Numerical simulations using standard FE and Wave Finite Element methods have been carried out in order to verify and visualize the wave propagation phenomenon in both intact and damaged pipes. A set of tests has been performed on straight and curved pipes with two different materials: PVC and steel. The interaction between generated waves and machined defects has been proven. Numerical and experimental results confirm some specific features in the wave reflection coefficient. Thereafter, an industrial pipeline of about sixty meters long and containing several features has been tested by the inspection system.Recorded signals had submitted some numerical treatments in order to make them interpretable. Processed signals are analyzed to identify defects reflections from structured singularities echoes. The Wave Finite Element Method (WFEM) has been used to construct a numerical database of reflection coefficients from modelled defects by varying thickness, axial and circumferential extents. Calculation was made depending on frequency. The approximation of defect sizes is carried out by sweeping the numerical database to find the suitable combination of dimensions fora given defect. Reflections from structural singularities (elbows, concrete blocks,clamps, and welds) are treated as well by comparing reflection coefficients obtained by WFEM to those evaluated experimentally. Finally, a numerical investigation deals with the effect of defect angular-position on reflection and transmission coefficients while exciting by different types of waves. The spectral method Wave Finite Element has been used to carry out calculation. This study gives guidance to circumferential localization of defects in pipes
23
Karri, Avinash. "Employment of dual frequency excitation method to improve the accuracy of an optical current sensor, by measuring both current and temperature". Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9766/.
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Optical current sensors (OCSs) are initially developed to measure relatively large current over a wide range of frequency band. They are also used as protective devices in the event a fault occurs due to a short circuit, in the power generation and distribution industries. The basic principal used in OCS is the Faraday effect. When a light guiding faraday medium is placed in a magnetic field which is produced by the current flowing in the conductor around the magnetic core, the plane of polarization of the linearly polarized light is rotated. The angle of rotation is proportional to the magnetic field strength, proportionality constant and the interaction length. The proportionality constant is the Verdet constant V (λ, T), which is dependent on both temperature and wavelength of the light. Opto electrical methods are used to measure the angle of rotation of the polarization plane. By measuring the angle the current flowing in the current carrying conductor can be calculated. But the accuracy of the OCS is lost of the angle of rotation of the polarization plane is dependent on the Verdet constant, apart from the magnetic field strength. As temperature increases the Verdet constant decreases, so the angle of rotation decreases. To compensate the effect of temperature on the OCS, a new method has been proposed. The current and temperature are measured with the help of a duel frequency method. To detect the line current in the conductor or coil, a small signal from the line current is fed to the reference of the lock in. To detect the temperature, the coil is excited with an electrical signal of a frequency different from the line frequency, and a small sample of this frequency signal is applied to the reference of the lock in. The temperature and current readings obtained are look up at the database value to give the actual output. Controlled environment is maintained to record the values in the database that maps the current and temperature magnitude values at the DSP lock in amplifier, to the actual temperature and current. By this method we can achieve better compensation to the temperature changes, with a large dynamic range and better sensitivity and accuracy.
24
Gross, Jonah M. "Development of acoustic transducers for use in the parametric pumping of spin waves". Thesis, 2013. http://hdl.handle.net/1957/37905.
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The work detailed here is the development of simulations and fabrication techniques used for the construction of thin-film acoustic transducers for use in the parametric pumping of spin waves. The Mason Model, a 1-D equivalent circuit simulating the responses of multilayer acoustic transducers, is implemented using ABCD-parameters in MATLAB to determine the expected response from fabricated devices. The simulation is tested by varying device parameters and comparing the changes in device resonance response to those of prior published results. Three-layer thin-film acoustic transducers were also fabricated. These transducers use zinc oxide (ZnO) as a piezoelectric layer with aluminum (Al) electrodes. Construction is accomplished using the common thin-film fabrication techniques of sputtering, thermal evaporation, etching, and lift-off patterning processes. The response of the fabricated transducers is compared to that of the simulated response by observing the transducer's resonance frequency and characteristics. These results are used to validate the simulation and the transducer fabrication process. Finally, their usefulness for the design and fabrication of an acoustic spin wave amplification system is considered.Graduation date: 2013
25
Dangi, Ajay. "Piezoelectric Micromachined Ultrasound Transducers : From Design to Applications". Thesis, 2016. http://etd.iisc.ernet.in/2005/3737.
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Ultrasonic sensors are well known for various applications such as NDT, ultrasound imaging, and proximity sensing. Conventional ultrasound transducers are bulky, work at notoriously high voltages, and consume significant power. Microfabrication techniques are leading to a paradigm shift in the field of ultrasonics by enabling development of low power - small footprint ultrasound transducers.
This work focuses on the development of piezoelectric type flexural mode micromachined ultrasound transducer also known as PMUTs. We start by establishing a system level analytical model of a PMUT and use it to offer insights into scaling of the performance of the transducer with respect to various design parameters. In this analysis we give special attention to residual stresses thus establishing a contrast between membrane type and plate type PMUTs. After going through various steps of material development and microfabrication, we obtain arrays of PMUTs with different designs. PZT thin films deposited by sol-gel method are used as the piezoelectric layer in the multilayer stack. Further, we present a thorough characterization of fabricated PMUTs which includes measurement of the piezoelectric properties of the embedded PZT thin film, electrical impedance of the electromechanical transducer, its vibrational charac-teristics and acoustic radiation from a single PMUT cell. We also develop a pre-amplifier circuit for a PMUT receiver and present its working as a simple proximity sensor. After establishing the repeatability and predictability of our PMUT sensors we delve into application development beyond ultrasound imaging. Experiments and analysis of PMUTs submerged in water show strong structural-acoustic coupling between the PMUT membrane and the surrounding fluid. We hypothesize the applicability of this feature to sense changes in the acoustic environment of a PMUT. To this end, we integrate an array of PMUTs with a micro-fluidic chip and study the changes in the vibrational behaviour of the PMUT in response to change in the air-water ratio in a closed cell around a PMUT membrane. We also present our preliminary results on presence of micro-bubbles in the closed cell around the PMUT.
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Ko, Chung-Ting y 柯忠廷. "Design and Characterization of Acoustic Matching Layers for Piezoelectric Ultrasonic Transducers". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/69843913545092115562.
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碩士國立臺灣大學
材料科學與工程學研究所
95
A novel active matching layer made of lead zirconate titanate (PZT) plate has been developed as an “impedance matching layer” for high-intensity focused ultrasound (HIFU) applications. The PZT matching layer redistributes the frequency spectrum of an original broadband ultrasonic probe, and acts as a frequency filter without reducing the wave amplitude. These behaviors are contributed to electromechanical and mechanical properties at the PZT matching layer, and are investigated in this study by a series of experiments on PZT matching plates with different electromechanical properties and polarization and surface charge conditions. Traditional passive matching layers, such as ceramic-polymer composites, are also studied. Three different ceramic-epoxy composite are developed and their impedance properties studied. Among the three, the zirconium oxide-epoxy composite exhibits a tolerable attenuation level and an optimum impedance value. It is then integrated on to a home-made HIFU transducer to test its effectiveness. The beam profile of the matched HIFU transducer is characterized by a hydrophone, and an in-vivo experiment is carried out to gauge its performance. In this study, structure materials such as porous ceramics and porous ceramic-epoxy composites are also proposed as candidate materials for impedance matching for water and human tissues due to their low attenuations and impedances.
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Liu, Chia-cheng y 劉家誠. "Partial Distribution Electrode Design for Micro-machined Square Piezoelectric Laminae Transducers". Thesis, 1999. http://ndltd.ncl.edu.tw/handle/16542342216358536783.
Texto completoResumen
碩士國立臺灣大學
機械工程學研究所
87
As we examine mode shapes of a piezoelectric lamina transducer, actuation in some areas of the laminae is more effective than that in other areas. Therefore, for some desired mode shapes, suitable distribution of the electrode will elevate efficiency of electromechanical coupling. This paper studies the electromechanical behavior of the champed square piezoelectric/elastic thin laminae transducer. The piezoelectric/elastic lamina consists of a silicon dioxide laminated with piezoelectric material which is fabricated by Metallo-Organic Decomposition (MOD) method. The analysis is aimed at the dependence of the size and location of the distribution of the electrode on the dynamic performance. To study the characteristics of the laminae transducer an electroelastic plate theory, including the equilibrium equations, the geometric relationships, the constitutive relations and the electrostatic equations is developed. The theoretical model includes one part that is covered by electrode and the other without electrode. The dynamic behaviors of the transducer include resonance frequencies, dynamic strain energy and electromechanical coupling coefficient (EMCC). Numerical analysis is conducted and results illustrate the optimum distributed-electrode design of particular mode shape. It is found that the 80 % electrode distribution has the stronger electromechanical coupling effect than the full distributed ones.
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Ko, Chung-Ting. "Design and Characterization of Acoustic Matching Layers for Piezoelectric Ultrasonic Transducers". 2007. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2307200715501100.
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Nguyen, Kenneth Khai. "Design and comparison of single crystal and ceramic Tonpilz transducers". Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-08-1831.
Texto completoResumen
Transducers utilizing single crystal piezoelectrics as the active elements have been shown to exhibit broader operating bands, higher response levels, and higher power efficiency than transducers using piezoceramics while also reducing the size and mass of the transducer (Moffett et al., J. Acoust. Soc. Am., 2007). The key to these high performance characteristics is the piezocrystal's inherent high electromechanical coupling coefficient. One potential application is to replace multiple narrowband piezoceramic transducers with a single broadband piezocrystal transducer which reduces the system's weight and size. This is very important for the new generation of smaller and power efficient unmanned underwater vehicles (UUVs). A third application is for use in very broadband communication networks. The work presented here focuses specifically on the design, modeling, and construction of Tonpilz transducers using piezoelectrics as the active material. The modeling includes lumped element and finite element analysis to approximate the performance of these transducers. These models serve as the main structure of an overall iterative design process. The objective of this research is to compare the performance characteristics of a piezocrystal and a piezoceramic Tonpilz transducer and to validate the models by comparing the model predictions with experimental results.text
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Ahmad, Babar. "Design and Development of Capacitive Micromachined Ultrasonic Transducers". Thesis, 2012. http://hdl.handle.net/2005/3164.
Texto completoResumen
This thesis presents the design and analysis for development of a Capacitive Micromachined Ultrasonic Transducer (CMUT), a novel sensor and actuator, aimed at replacing the conventional piezoelectric transducers for air-coupled ultrasonic imaging applications. These CMUTs are fabricated using the silicon micromachining technology wherein all fabrication is done on the surface of a silicon wafer by means of thin-film depositions, patterning with photolithography and etching. The main emphasis of this study is on developing analytical models that serve as effective design tools for the development of these devices. A desirable goal of such study is to create reasonable mathematical models, obtain analytical solutions, wherever possible, for various measures of transducer performance and provide design aids.
A logical start is the lumped parameter modeling wherein the explicit dependence of the physical parameters on the spatial extent of the device is ignored. The system lumped parameters, such as the equivalent stiffness, the equivalent mass, and the equivalent damping are extracted from reasonable analytical or numerical models and subsequently used in the static and dynamic analysis of the device. Useful predictions are made with regard to the key transducer parameters, such as, the pull-in voltage, the static deflection, the dynamic response and the acoustic field produced. The modeling work presented embodies two main objectives: (i) it serves to provide direction in the design phase, and, (ii) it serves to aid in the extraction of critical parameters which affect the device behavior. Comparison of the results with the more rigorous FEM simulations as well as with those present in the existing literature assure that the developed models are accurate enough to serve as useful design tools.
The distributed parameter modeling is presented next. Analysis of MEMS devices which rely on electrostatic actuation is complicated due to the fact that the structural deformations alter the electrostatic forces, which redistribute and modify the applied loads. Hence, it becomes imperative to consider the electro-elastic coupling aspect in the design of these devices. An approximate analytical solution for the static deflection of a thin, clamped circular plate caused by electrostatic forces which are inherently nonlinear, is presented. The model is based on the Kirchhoff-Love assumptions that the plate is thin and the deflections and slopes are small. The classical thin-plate theory is adequate when the ratio of the diameter to thickness of the plate is very large, a situation commonly prevalent in many MEMS devices, especially the CMUTs. This theory is used to determine the static deflection of the CMUT membrane due to a DC bias voltage. The thin-plate electro-elastic equation is solved using the Galerkin weighted residual technique under the assumption that the deflections are small in comparison to the thickness of the plate. The results obtained are compared to those obtained from ANSYS simulations and an excellent agreement is observed between the two. The pull-in voltage predicted by our model is close to the value predicted by ANSYS simulations. A simple analytical formula, which gives fairly accurate results (to within 3% of the value predicted by ANSYS simulations) for determination of the pull-in voltage, is also presented. As stated, this formula accounts for the elastic deflection of the membrane due to the coupled interaction with the electrostatic field.
The effect of vacuum sealing the backside cavity of a CMUT is investigated in some detail. The presence or absence of air inside the cavity has a marked effect upon the system parameters, such as the natural frequency and the pull-in voltage. The possibility of using sealed CMUT cavities with air inside at ambient pressure is explored. In order to estimate the transducer loss due to the presence of air in the sealed cavity, the squeeze film forces resulting from the compression of the trapped air film are evaluated. Towards this end, the linearized Reynolds equation is solved in conjunction with the appropriate boundary conditions, taking the flexure of the membrane into account. From this analysis, it is concluded that, for a sealed CMUT cavity, the presence of air does not cause any squeeze film damping even when the flexure of the membrane is taken into account (the case of a rigid plate is already known).
Although the emphasis of the study undertaken here is not on the physical realization of a working CMUT, a single cell as well as a linear array based on the design presented here, were fabricated (in a foundry elsewhere) in order to verify some of the most fundamental device parameters from experimental measurements. The fabricated devices have been characterized for their resonant frequency, quality factor, and structural integrity. These tests were conducted using the laser Doppler vibrometer and the Focused Ion Beam milling.
Having investigated thoroughly the behavior of a single cell, we proceed to demonstrate how these cells can be arranged optimally in the form of an array to provide a comprehensive ultrasonic imaging system. A thorough analysis of the requirements for the array architecture is undertaken to determine the optimal configuration. The design constraints that need to be taken into account for CMUT arrays, especially for NDE applications, are presented. The main issue of designing an array consisting of a large number of CMUT cells required for producing a pressure wave of sufficient strength which is detectable upon reflection from the desired location even after suffering severe attenuation resulting from propagation in various media is addressed. A scalable annular array architecture of CMUT cells is recommended based on the analysis carried out.
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Liu, Tang-Jen y 劉堂仁. "Cooking Thermal Fumes Sensing with Piezoelectric Transducers and the Controller Design of Smart Kitchen Range Hoods". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/76snrq.
Texto completoResumen
博士國立成功大學
電機工程學系碩博士班
90
In the system design of the kitchen range hood, the exhaust fan is utilized to generate an adequate suction flow to eliminate the cooking contaminants. In the highly greasy environments such as Chinese-style kitchens, how to reduce the range hood noise and its power consumption to acceptable levels in an economical way is most concerned. In this thesis, a low-cost high-efficiency smart range hood system is proposed to control the noise and the power consumption in rational levels. In this system, a sensitive and inexpensive piezoelectric transducer is first adopted as the sensing device of cooking contaminants. Based on the function of the piezoelectric transducer, the proposed system is capable of adapting its suction flow rate automatically to an adequate level according to the amount of cooking contaminants detected by the transducer. According to experimental results, the noise level and the power consumption can be largely reduced with the help of the transducer and the microcontroller-based range hood system controller. In the typical heavy frying of vegetable common in Chinese-style kitchens, the obtained noise level is 65.66 dB and the power consumption is 123.97 W on average. They are much less than those of the conventional range hood system without control, which are 72 dB and 216 W, respectively.
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"Feasibility studies of self-powered piezoelectric sensors". 2004. http://library.cuhk.edu.hk/record=b5892014.
Texto completoResumen
Ng Tsz Ho.Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.
Includes bibliographical references (leaves 67-70).
Abstracts in English and Chinese.
ABSTRACT --- p.i
摘要 --- p.ii
ACKNOWLEDGEMENTS --- p.iii
LIST OF FIGURES --- p.iv
LIST OF TABLES --- p.ix
Chapter CHAPTER 1 --- INTRODUCTION --- p.1
Chapter 1.1 --- Background --- p.1
Chapter 1.2 --- Literature Review --- p.3
Chapter 1.3 --- Research Objectives --- p.5
Chapter 1.4 --- Thesis Organization --- p.5
Chapter CHAPTER 2 --- MODELING OF PIEZOELECTRIC SENSOR/GENERATOR --- p.6
Chapter 2.1 --- Constitutive Equations --- p.6
Chapter 2.2 --- Voltage Output of Piezoelectric Materials --- p.9
Chapter 2.2.1 --- Short Circuit --- p.9
Chapter 2.2.2 --- Open Circuit --- p.11
Chapter 2.3 --- Sensitivity and Power Generation --- p.13
Chapter 2.4 --- Modeling and Analysis of Sensor Structure --- p.23
Chapter 2.4.1 --- Damping Ratio Estimation --- p.25
Chapter (a) --- Half-power bandwidth method --- p.25
Chapter (b) --- Linear interpolation method --- p.25
Chapter 2.4.2 --- Trade-off between Resonant Frequency and Output Sensitivity of a Sensor --- p.29
Chapter (a) --- Maximize Sme with constant wn --- p.31
Chapter (b) --- Maximize wn with constant Sme --- p.33
Chapter 2.5 --- Model Accuracy --- p.39
Chapter CHAPTER 3 --- POWER HARVESTING --- p.41
Chapter 3.1 --- Circuit Model --- p.41
Chapter 3.2 --- Energy Storage --- p.47
Chapter 3.3 --- Size Effect on Power Output --- p.49
Chapter 3.4 --- Power Harvesting Circuit --- p.50
Chapter 3.4.1 --- Performance of the Power Harvesting Circuit --- p.51
Chapter (a) --- Power Harvesting Circuit Efficiency --- p.52
Chapter (b) --- Useful Power Output --- p.53
Chapter (c) --- System Efficiency --- p.56
Chapter (d) --- Relationship between Input Excitation and Charge Time --- p.57
Chapter 3.5 --- Harvested Energy for Wireless Transmission --- p.60
Chapter CHAPTER 4 --- CONCLUDING REMARKS --- p.64
Chapter 4.1 --- Sensor/Generator Design --- p.64
Chapter 4.2 --- Potential Applications --- p.64
Chapter 4.3 --- Conclusion --- p.65
Chapter 4.4 --- Future Work --- p.66
REFERENCES --- p.67
APPENDIX --- p.71
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Wangcharoenrung, Chayawee. "Development of adaptive transducer based on biological sensory mechanism". Thesis, 2005. http://hdl.handle.net/2152/1718.
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"A PVDF-based sensing system for automated micro-manipulation". 2002. http://library.cuhk.edu.hk/record=b5891131.
Texto completoResumen
Fung, Kar Man.Thesis (M.Phil.)--Chinese University of Hong Kong, 2002.
Includes bibliographical references (leaves 110-114).
Abstracts in English and Chinese.
摘要 --- p.i
ABSTRACT --- p.ii
ACKNOWLEDGMENTS --- p.iii
TABLE OF CONTENTS --- p.iv
LIST OF FIGURES --- p.vi
Chapter 1. --- Introduction --- p.1
Chapter 1.1 --- Background and Motivation --- p.1
Chapter 1.2 --- Objective of the project --- p.4
Chapter 1.3 --- Organization of the thesis --- p.5
Chapter 2. --- Literature Review --- p.7
Chapter 2.1 --- Control on Micro-Manipulation --- p.7
Chapter 2.1.1 --- Visual Feedback Control --- p.8
Chapter 2.1.2 --- Sensor-Based Feedback Control --- p.9
Chapter 2.1.3 --- Bilateral Control --- p.9
Chapter 2.2 --- Force Sensing System on Micro-Manipulation --- p.10
Chapter 2.3 --- PVDF Sensor --- p.11
Chapter 2.4 --- Summary of the Literature Review --- p.12
Chapter 3. --- Micro-Manipulation --- p.14
Chapter 3.1 --- Introduction of Micro-Manipulation --- p.14
Chapter 3.2 --- Probe Station --- p.14
Chapter 3.2.1 --- Micromanipulators --- p.15
Chapter 3.2.2 --- Microscopes --- p.15
Chapter 4. --- Piezoelectric Polyvinylidence Fluoride (PVDF) Sensor --- p.16
Chapter 4.1 --- Charteristic of PVDF Sensor --- p.16
Chapter 4.1.1 --- Piezoelectric Properties --- p.16
Chapter 4.1.2 --- Dimensions of the PVDF Sensor --- p.18
Chapter 4.2 --- Comparison of Piezoelectric Materials --- p.19
Chapter 5. --- Theoretical Analysis of PVDF Sensor --- p.21
Chapter 5.1 --- Sensitivity of PVDF Sensor --- p.21
Chapter 5.2 --- Relationship between the Deflection and the Force of the PVDF --- p.22
Chapter 5.3 --- Calculation of the Spring Constant K of the PVDF --- p.23
Chapter 5.4 --- Simulation on the output from the PVDF Sensor --- p.23
Chapter 6. --- Experimental Analysis of PVDF Sensor --- p.26
Chapter 6.1 --- Force-Deflection Diagram --- p.26
Chapter 6.2 --- Frequency Response of the PVDF Sensor --- p.27
Chapter 7. --- 1-D PVDF-Based Sensing System --- p.30
Chapter 7.1 --- Original Design of the Sensing System --- p.30
Chapter 7.1.1 --- Plastic pipe and adapter --- p.31
Chapter 7.1.2 --- PVDF Sensor --- p.32
Chapter 7.1.3 --- Probe-tip holder --- p.32
Chapter 7.2 --- Current Design of the Sensing System --- p.32
Chapter 7.3 --- Analysis of the Sensing System --- p.34
Chapter 7.3.1 --- Frequency Response of the Sensing System --- p.34
Chapter 7.3.2 --- Sensitivity of the Sensing System --- p.41
Chapter 8. --- Experiments on 1-D PVDF Sensing System --- p.49
Chapter 8.1 --- Experimental Setup of the 1-D Sensing System --- p.49
Chapter 8.1.1 --- Programmable Micromanipulator --- p.50
Chapter 8.1.2 --- Charge Amplifier --- p.51
Chapter 8.2 --- Calibration of the 1-D Sensing System --- p.53
Chapter 8.2.1 --- Noise Signal from the system --- p.53
Chapter 8.2.2 --- Signal from vibration --- p.55
Chapter 8.3 --- Experimental Results on touching a substrate --- p.60
Chapter 8.3.1 --- Description --- p.60
Chapter 8.3.2 --- Results from touching a substrate --- p.62
Chapter 8.3.3 --- Analysis of the deflection after touched a substrate --- p.67
Chapter 8.4 --- Experimental Results on touching a micro mirror --- p.68
Chapter 8.4.1 --- Description --- p.68
Chapter 8.4.2 --- Results --- p.70
Chapter 8.5 --- Experimental Results on lifting a mass platform --- p.74
Chapter 8.5.1 --- Description --- p.74
Chapter 8.5.2 --- Results --- p.76
Chapter 9. --- Modification of 1-D Sensing System --- p.79
Chapter 9.1 --- Design of the system --- p.79
Chapter 9.2 --- Experimental Setup of the system --- p.80
Chapter 9.3 --- Experimental Results on lifting a mass platform --- p.81
Chapter 10. --- 2-D PVDF-Based Sensing System --- p.90
Chapter 10.1 --- Design of the Sensing System --- p.90
Chapter 10.2 --- Experimental Setup --- p.91
Chapter 10.3 --- Calibration of the 2-D Sensing System --- p.92
Chapter 10.3.1 --- Noise Signal from the system --- p.92
Chapter 10.4 --- Experiments Results on touching a substrate --- p.94
Chapter 11. --- Experimental Analysis --- p.97
Chapter 11.1 --- Data Acquisition --- p.97
Chapter 11.2 --- Spectrum Analysis of the Experimental Data --- p.101
Chapter 12. --- Conclusion --- p.103
Chapter 13. --- Future Work --- p.105
Chapter 13.1 --- Control of the Sensing System --- p.105
Chapter 13.2 --- Tele-operation System on force feedback sensing system --- p.107
Chapter A. --- Appendix --- p.109
Chapter A. 1 --- Procedures in using probe station --- p.109
Bibliography --- p.110