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 135 for “"resonance frequency"”.
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Energy Harvesting toward the Vibration Reduction of Turbomachinery Blades via Resonance Frequency Detuning
… reducing turbomachinery blade vibrations, namely resonance frequency detuning. In contrast with the bulk of energy harvesting research, this effort is not focused on maximizing the power output of the system, but rather providing the low power levels required by resonance frequency detuning. The …
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Determination of Frequency-Based Switch Triggers for Optimal Vibration Reduction via Resonance Frequency Detuning
Resonance frequency detuning (RFD) is a piezoelectric-based vibration reduction approach that applies to systems experiencing transient excitation through the system*s resonance—for example, turbomachinery experiencing changes in rotation speed, such as on spool-up and spool-down. This technique …
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Factors affecting the dynamic response of the body and the vibration transmitted through seats
… In a rigid seat with no backrest, there were resonances in the apparent<br/>mass of the body around 5 and 10 Hz (with 1.0 ms-2 r.m.s broadband vibration). In the same seat<br/>with a rigid backrest, the median resonance frequency in the apparent mass increased from 5.47 to<br/>6.35 Hz as the …
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Design of LCL-filters for grid-connected voltage source inverters
… the grid-side and inverter-side inductors, resonance frequency, reactive power production and attenuation of higher order harmonics in an LCL-filter. Based on the analysis, this thesis proposes a generalised LCL-filter design algorithm which avoids uncertainty in determining resonance …
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Dynamic Behavior of Sandwich Beams With Internal Resonators
… a wave attenuation bandgap exists due to local resonance. Steady state experiments were used to demonstrate such an attenuation bandgap. Frequency response functions were obtained for a beam with resonators and without resonators. It was shown that insertion of resonators into the core causes a …
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Mechanism of nonlinear biodynamic response of the human body exposed to whole-body vibration
… body is exposed to mechanical vibration, the resonance frequencies of the frequency response functions, such as apparent mass and transmissibility, decrease with increasing magnitude of excitation. For the past two decades, this biodynamic ‘nonlinearity’ has been reported with vertical and …
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Characterization, Modeling of Piezoelectric Pressure Transducer for Facilitation of Field Calibration
… pressure transducer. This document presents the frequency curve fitted model based on the high frequency excitation of the piezoelectric pressure transducer. It also presents the time domain model of the sensor. The time domain response of the frequency curve fitted model obtained in parallel …
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Damping and stiffening forces of a squeeze-film between two plates
… the stiffening effect, which affects the resonance frequency of the squeeze film and oscillator system. In this research, the finite difference method for rectangular geometries is applied to solve the nonlinear isothermal Reynold's equation for the squeeze film. The approach is validated …
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Determination of the Magnetic Structure of the Antiferromagnetic State of the Organic Superconductor Kappa-(bedt)(2)copper Dicyanamide Chloride Using Nuclear Magnetic Resonance and Magnetometry
… ordering was not understood. Our 13C NMR resonance frequency data in the magnetic state, combined with our analysis of symmetry of the system, show conclusively that the ordering is antiferromagnetic and provide a precise picture of the spin ordering.
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Determination of the Magnetic Structure of the Antiferromagnetic State of the Organic Superconductor k-(BEDT)2Cu[N(CN)2]Cl Using Nuclear Magnetic Resonance and Magnetometry
… ordering was not understood. Our 13C NMR resonance frequency data in the magnetic state, combined with our analysis of symmetry of the system, show conclusively that the ordering is antiferromagnetic and provide a precise picture of the spin ordering.
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Acoustic function of sound hole design in musical instruments
… introducing a natural vibration mode called air resonance. Many musical instruments, including those from the violin, lute and oud families have evolved complex sound-hole geometries through centuries of trail and error. However, due to the inability of current theories to analyze complex …
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Simulation of strongly injection-locked semiconductor ring lasers
… is presented. This scheme involves a single-frequency master laser monolithically integrated with strongly injection-locked whistle-geometry semiconductor ring lasers. Improved high-speed performance of the novel scheme is confirmed through numerical modeling, showing greatly enhanced …
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Electronic and Plasmonic Properties of Nano-Sized Gold/Strontium Titanate Interface
… targeted at near-infrared working range. Plasmon resonance frequency and intensity are demonstrated to be systematically tunable by varying device geometry. Photocurrent enhancement occurs around the resonance frequency, resulting from amplified absorption of plasmon resonance. Finally, possible …
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Method for single-cell mass and electrophoretic mobility measurement
… single cells with femtogram resolution. The net frequency shift of a resonant cantilever as the cell transits the fluid-filled microchannel running through it is proportional to the buoyant mass of the cell. The resonance frequency of the SMR is also highly sensitive to a cell's position along …
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Factors Affecting the Primary Stability of the Intraosseous Screw Type Implants /// Фактори повлияващи първичната стабилност на интраосалните винтови имплантати
… insertion torque (MIT), damping capacity and resonance frequency analysis, and heat generation during the insertion of implants recorded by a thermal camera.
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Nanoscale Control of Gap-plasmon Enhanced Optical Processes
Surface plasmon resonances of metal nanostructures have been studied intensely in recent years. The strong plasmon-mediated electric field enhancement and field confinement well beyond the diffraction limit has been demonstrated to improve the performance of optical devices including ultrasensitive …
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Design and Fabrication of a Nanocantilever for High-Speed Force Microscopy
… potential of these systems, a cantilever with a resonance frequency much greater than 100 MHz is required. Unfortunately, current microfabrication techniques used to produce AFM cantilevers limits the fundamental resonance frequency to several MHz. The purpose of this project was to miniaturize a …
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Engineered Plasmonic Nanostructures for Infrared Spectroscopy, Refractive Index Sensing and Nonlinear Optics
… researchers studied the dependence of plasmon resonance frequency on the size, shape and dielectric environment of the nanoscale system, mainly for sensing applications. The intense and localized field, generated by two adjacent metallic nanostructures when appropriately illuminated, has been …
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High precision electrohydrodynamic printing of polymer onto microcantilever sensors
… by examining the shift in microcantilever resonance frequency resulting from droplet deposition. The resonance shift of 50 - 4130 Hz corresponded to a polymer mass of 4.5 - 135 pg. The electrohydrodynamic method is a precise way to deposit multiple materials onto micromechanical sensors …
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The two-dimensional vibrating reed technique: a study of anisotropic pinning in high-temperature superconductors
… a typical magnetic field dependence of the resonance frequency. Such an experimental configuration has never been used before and gives the possibility to study the symmetry of the pinning potential. A mathematical model was developed to describe the effect of anisotropy of the pinning …
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