Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 37 for “"Piezoelectric Effect"”.
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The Piezoelectric Effect of Bone In Vitro
… stress, is incompletely understood. The direct piezoelectric properties of bone have been suggested as playing an active role in the internal morphology of bone tissue.</p> <p>This study was designed to fabricate an apparatus and develop a technique to measure, quantitatively, the direct …
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The hydrogen-induced piezoelectric effect in InP HEMTs
… This is a serious reliability concern. This effect has been attributed to a H-induced piezoelectric effect. Formation of TiH[sub]x expands the Ti layer in the gate, causing mechanical stress in the underlying semiconductor. This induces piezoelectric charge in the heterostructure underneath …
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Ferroelectric Barium Titanate Nanowires: Synthesis, Properties, and Device Applications
… BaTiO3 nanowire. In this device, due to the piezoelectric effect, voltage response was generated from the BaTiO3 nanowire by a periodically varying tensile mechanical strain applied with a precision mechanical testing stage. The measured voltage generation from the nanowire was found to be …
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The effects of embedded piezoelectric layers in composite cylinders and applications
… cylinder under loadings due to embedded piezoelectric laminae. The solution is used to study both uniform and non-uniform distributions of the piezoelectric effect and results are verified using the finite element method. A cylindrical truss element actuator is developed based upon this …
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Ultra wide-bandwidth micro energy harvester
… at a wide range of amplitude and frequency via piezoelectric effect. At the present time, the designs of most piezoelectric energy devices have been based on high-Q linear cantilever beams that use the bending strain to generate electrical charge via piezoelectric effect. They suffer from very …
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A Study of the Nucleation and Formation of Multi-functional Nanostructures using GaN-Based Materials for Device Applications
… relationship between quantum confinement (and/or piezoelectric polarization) and the dot size. For dot height < 4.1nm, the confinement effect is larger than the piezoelectric effect, otherwise the piezoelectric effect is more dominant. In addition, GaN nanostructures grown on Al0.15Ga0.85N have …
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Electrostatic effects of inhomogeneous strain in monolayer transition metal dichalcogenides
… metal dichalcogenides exhibit a significant piezoelectric effect that can couple with spatially inhomogeneous strain distributions to influence electronic and optical behavior. In this work, inhomogeneous strain and piezoelectricity in transition metal dichalcogenides are studied. We first …
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Mems approaches in infrared imaging
… physically interfaced with different types of piezoelectric resonators, constructed using the MEMS process. The expansion due to heating, applies stress to the piezoelectric resonator material. This thermally induced stress forces the resonator to alter its physical frequency and produces a …
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Investigation of Degradation Effects Due to Gate Stress in GaN-on-Si High Electron Mobility Transistors Through Analysis of Low Frequency Noise
… HEMT channel region is undoped and relies on the piezoelectric effect created at the GaN and Aluminum Gallium Nitride (AlGaN) heterojunction to create a conduction channel in the form of a quantum well known as the two dimensional electron gas (2DEG). Because the GaN HEMTs are undoped, these …
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The electromechanical effect in bone
Although bone is piezoelectric, the signal from bent bone cannot be described by the piezoelectric effect if the samples are assumed to be homogeneous. To account for the symmetry properties and z-dependence of the signal from dry bone in cantilever bending, a theory postulating a polarization …
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Characterization of Nanoporous Polyvinylidene Fluoride (PVDF) Sensors under Tensile Loading
Piezoelectric materials are one of the currently smart materials. They have achieved great success in biologic medical and electrical applications, as fluorocarbon coatings and other areas. They have shown thriving prospects in the ongoing research and commercialization process. To improve the …
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Characterization of a piezoelectric transformer plasma source
The piezoelectric transformer plasma source (PTPS) is a compact RF driven plasma source developed for near-space and microspacecraft propulsion. The PTPS uses the mass transfer of emitted charged particles from the plasma to produce thrust. The PTPS utilizes the piezoelectric transformer effect to …
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Degradation study of AIGaN/GaN HEMT through electro-thermo-mechanical calculations and thermo-reflectance measurements
… transistors. Since AIGaN and GaN are both piezoelectric materials, the coupling among electric field, lattice heating and mechanical characteristics gives rise to large changes in strain field and elastic energy density in the transistors under the pinch-off conditions. Most previous work …
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Reliability of GaN high electron mobility transistors on silicon substrates
… that high voltage stress conditions are more effective in degrading the device than high current conditions. High voltage stress is found to impact the device in two different ways. The first is increased trapping in the large number of traps in the highly mismatched device structure even …
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Dual Mode Macro Fiber Composite-Actuated Morphing Tip Feathers for Controlling Small Unmanned Aircraft
… (MFC), a smart material, takes advantage of the piezoelectric effect and provides an attractive alternative actuator to servos in the Small Unmanned Aerial Systems (SUAS) regime of flight. This research looks to take MFC actuated control surfaces one step further by pulling inspiration from and …
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Piezoelectric active sensor and electric impedance approach for structural dynamic measurement
The increasing use of piezoelectric material in the last decade has led to the new discovery that piezoelectric devices may be used not only as sensors or actuators individually, but also as a sensor and actuator at the same time. This bi-directional phenomenon greatly expands the utility of …
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Modeling Energy Harvesting From Membrane Vibrations using Multi-physics Modeling
… research focuses on energy harvesting using the piezoelectric effect, from vibrating membrane structures by converting mechanical energy into electric energy. Specific applications of this research include powering components of bio-inspired micro air vehicles (MAVs), which require long range …
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Vibration Attenuation of Composite Moving Beams using Active Vibration Control Techniques
… vibration control technique that employs the piezoelectric effect. Piezoelectric sensors and actuators are added to the beam to sense and control the vibrational response of the moving beam. The sensors and actuators are made to communicate with each other using negative velocity feedback …
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I. Resonant two-proton reabsorption by exition-polaritons in cuprous chloride films ; II. Heat pulse progration across metal/sapphire interfaces ; III. Phonon focusing in piezoelectric crystals
… theory. The third type of feature is a surface effect in which a consentration of transverse phonons near the critical cone for mode conversion from bulk transverse waves to longitudinal waves along the surface. It is found to be dependent on surface orientation and is very sensitive to surface …
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Theoretical Parametric Study of Through-Wall Acoustic Energy Transfer Systems
… and receiver layers are constructed of a piezoelectric material. Piezoelectric materials behave according to the piezoelectric effect, which is when a material generates an electric charge in response to mechanical strain. The transmitter utilizes the reverse of the piezoelectric effect. A …
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