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 477 for “"frequency response"”.
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A Study of Constant Voltage Anemometry Frequency Response
… velocity fluctuations in the boundary layer. The frequency response of a sensor operated by CVA has been studied analytically and experimentally. The thermal lag of the sensor is quantified by a time constant, <em>M<sub>CVA</sub></em>. When the time constant is decreased, the half-amplitude …
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Variable temperature high-frequency response of heterostructure transistors
The development of high performance heterostructure transistors is essential for emerging opto-electronic integrated circuits (OEICs) and monolithic microwave integrated circuits (MMICs). Applications for OEICs and MMICs include the rapidly growing telecommunications and personal communications …
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Camera Spatial Frequency Response Derived from Pictorial Natural Scenes
… for measuring the edge-based Spatial Frequency Response (e-SFR), a sister measure of the MTF designed for measuring discrete systems. Many modern camera systems incorporate non-linear, highly adaptive image signal processing (ISP) to improve image quality. As a result, system …
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Design and development of a composite frequency response analyser
This thesis examines the role that composite frequency test signals play in system identification. The advantages and disadvantages of composite frequency response analysers over conventional analysers are discussed. Two low peak-factor composite frequency test signals are reviewed which largely …
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Damage detection in structures using measured frequency response function data
Modern engineering structures such as offshore oil platforms, transmission towers, bridges and aircraft frames are regularly monitored and maintained in order to avert catastrophic failure. Despite our best efforts, sporadic failures, which may have disastrous consequences in terms of human life …
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Frequency response of human skin in vivo to mechanical stimulation
The frequency-dependent response of human skin was measured, in vivo, to mechanical stimulation at a scale useful in the development of tactile displays. Sinusoidal vibration stimuli of varying frequencies and amplitudes were applied with a flat-ended 0.5 mm diameter cylindrical probe under two …
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Nonlinear vibration and frequency response analysis of piezoelectric-based nanotube resonators
… flow and structure curvature are developed. The frequency responses of proposed models for both free and forced vibrations under single frequency, multi-frequency and parametric excitations are investigated. The Hamiltonian principle and Lagrangian method are associated with non-local …
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Changes to system inertia and the impact on frequency response requirements
… concerns about the assurance of frequency stability and the adequacy ofdynamic frequency responses at low inertia. In islanded power systems, like those ofIreland and Great Britain (GB), understanding the issues posed and deploying effectivesolutions benefit from an investigation …
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Supra-Characteristic-Frequency Response in Gerbil Auditory Nerve Frequency Tuning Curves
… cell excitation and auditory nerve fiber (ANF) responses. The goal of this study is to better understand the mechanics of inner hair cell excitation which leads to hearing. BM motion and ANF tuning are generally very similar, but the ANF had appeared to be unresponsive to a plateau mode of BM …
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On Verification of Load Models for Frequency Response Using PMU Data
During frequency excursions, not only generators respond to the frequency deviation. Most electric loads are sensitive to large variations in frequency that change their power consumption as a result. Therefore, load modeling is a crucial element in power system simulation, and a better …
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A generalized form for frequency-response modeling of battery energy storage systems
The increasing reliance on rechargeable batteries necessitates advanced diagnostic tools. This thesis identifies and validates a generalized 14 parameter distributed equivalent circuit model (dECM) capable of describing the electrochemical impedance behavior of three commercial battery chemistries: …
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Frequency Response of an Agricultural Fence and the Implications for Data Transmission
… has been conducted into determining the optimum frequency bands to transmit in to give optimum performance. We propose that the fence spectrum be split into three frequency bands. A Fence Pulse Guard Band which extends from DC to 10 kHz, a Low Frequency Channel which extends from 10 kHz to 250 …
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The characteristic of frequency response on winding faults and configurations of transformer
… configurations of power transformers using Frequency Response Analysis (FRA). The frequency response provides indications of any mechanical and electrical changes in the transformer’s active parts. Three units of three-phase transformers were tested with the aim to investigate their FRA …
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Future power system dynamic frequency response under high penetration levels of wind
… variable speed wind turbine will not have a load-frequency response similar with traditional synchronous generator which may cause the inertia less problems in the system. The UK National Grid has developed scenarios where high wind power penetration levels are considered which are likely to …
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Frequency Response Modeling of Additive Friction Stir Deposition Parts with Print Defects
A change in a part's response to vibrations can be measured and utilized as a non-destructive testing method to detect deviations in the part's materials or geometry through processes such as laser acoustic resonance spectroscopy. This work focuses on leveraging vibration resonance to detect flaws …
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A Bayesian statistics approach to updating finite element models with frequency response data
… the task of updating finite element models with frequency response data acquired in a structural dynamics test. Standard statistical techniques are used to generate statistically qualified data, which is then used in a Bayesian statistics regression formulation to update the finite element model. …
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DC fault protection in HVDC system and the impact on AC frequency response
… system inertia and weakens the effect of primary frequency regulation leading to larger frequency derivation in the event of large transients. This thesis investigates frequency support strategies utilizing the flexible power flow controllability of MMC-HVDC. Different control strategies for …
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Methods to ensure the adequate primary frequency response of low inertia power systems
… systems with lower inertia and reduced governor response. The expected continuation of this decline motivates research on economical methods to ensure primary frequency response (PFR) adequacy and prevent frequency-related emergency actions. This dissertation describes both demand-side and …
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