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 50 for “"forced response"”.
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Nonlinear forced response of circular cylindrical shells
… multiple scales is used to analyze the nonlinear forced response of circular cylindrical shells in the presence of internal (autoparametric) resonances. If ω<sub>f</sub> and a<sub>f</sub> denote the frequency and amplitude of a flexural mode and ω<sub>b</sub> and a<sub>b</sub> denote the frequency …
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Forced response predictions in modern centrifugal compressor design
… between impeller-diffuser interactions and the forced response behavior of the impeller blades. Through comparison of time- averaged flow variable and performance estimates with test rig data, the three- dimensional, unsteady, Reynolds-averaged Navier-Stokes flow solver (MSU Turbo) used in this …
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Development of a Concept for Forced Response Investigations
… engine design tools, free flutter as well as forced response will be investigated in the 1.5 stage transonic compressor at TU Darmstadt. Aim of the forced response campaign is to determine the system damping in the stable compressor regime. Hence a novel excitation system capable of …
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Forced Response System Identification of Full Aero-Engine Rotordynamic Systems
… This thesis presents a first-of-its-kind forced-response system identification approach to measuring rotordynamic damping of shaft modes in a full gas turbine aero-engine. A reduced-order modeling framework that captures the full-engine dynamics by incorporating the coupling between rotor …
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Flutter and Forced Response of Turbomachinery with Frequency Mistuning and Aerodynamic Asymmetry
… sensitivity studies are conducted on flutter and forced response due to frequency mistuning and aerodynamic asymmetry using the single family of modes approach by assuming manufacturing tolerance. The unsteady aerodynamic forces are computed using CFD methods assuming aerodynamic symmetry. The …
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Forced Response Measurements of Cavitation Dynamics in a Rocket Engine Turbopump Inducer
… thesis introduces a foundation for a method of forced response characterization of cavitating inducers and presents for the first time, damping ratio and natural frequency measurements of surge dynamics using a forced response system identification approach over different cavitation numbers. …
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Forced response of a centrifugal compressor stage due to the impeller-diffuser interaction
… to identify the physical mechanisms that set the forced response amplitude of an impeller due to the impeller-diffuser interaction. The centrifugal stage researched is comprised of a stationary discrete passage diffuser and an unshrouded rotating impeller with both main and splitter blades. The …
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Axon Guidance Autonomy and Tensional Requirement for Synaptic Function: Is Learning a Forced Response
… processes whose growth cones exhibit different responses to their environment. In culture, detached growth cones display guidance autonomy, contain mRNA for cytoskeletal and other axonal components, and are capable of synthesizing protein locally. However, the extent to which growth cone's …
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Natural and forced response measurement of hydrodynamic stability in an aircraft gas turbine engine
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1994.
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Effects of Inlet Guide Vane Flow Control on Forced Response of a Transonic Fan
… high-cycle fatigue of compressor blades is the response to aerodynamic forcing functions generated by an upstream row of stators or inlet guide vanes. Resonant response to engine order excitation at certain rotor speeds is especially damaging. Studies have shown that flow control by trailing …
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The effects of temperature distortion on aerodynamics and low engine order forced response in axial turbines
… impact on the turbine aerodynamics and forced response excitation levels originating from the different hot flow patterns. Motivated by the lack of relevant studies, the current work provides a first step towards the evaluation of the effects of syngas on hot streaks aerodynamics and the …
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Dynamics of freshwater plumes : observations and numerical modeling of the wind-forced response and alongshore freshwater transport
… horizontal currents. The first order plume response is explained by Ekman dynamics and a Richardson number mixing criterion. Under a sustained wind event, the plume evolves to a quasi-steady, uniform thickness. The rate of mixing slowly decreases for longer times as the stratification in the …
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Dynamics of freshwater plumes: observations and numerical modeling of the wind-forced response and alongshore freshwater transport
… horizontal currents. The first order plume response is explained by Ekman dynamics and a Richardson number mixing criterion.
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Study of the effect of sensor position on the forced response characteristics of rotors with active magnetic bearings
… methods for rotor analysis, to predict the response of rotor systems with active magnetic bearings. The position of the magnetic bearing sensors is taken into account and the effect of changing sensor position on the vibrational characteristics of rotor systems is studied. The modified …
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Probabilistic vibration analysis of nearly periodic structures
… structure with weakly coupled subsystems. The forced excitation of localized modes may affect the maximum response amplitude of the system. Two nearly periodic structures are analyzed herein: a two span beam and a pair of coupled pendula. Results show that the sensitivity of the forced response …
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The surface propagation of ground vibration
… have been studied, and used to interpret the forced response results.The forced response problem has been extended to include masses either at the load, at the response point or between the load and response point, to study the value of isolation masses.
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The Influence of a Skewed Disk on a Flexible Rotating Shaft
… to verify the existing theory of skewed disk forced response predictions. The experimental tests were conducted on a horizontal flexible shaft rotor system supported in two hydrodynamic journal bearings. The computer simulations were conducted with a program that uses a matrix transfer method …
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The influence of the land-sea breeze on coastal upwelling systems
The land-sea breeze is resonant with the inertial response of the ocean at the critical latitude of 30° N/S, however its role in the physical and biogeochemical functioning of eastern boundary upwelling systems (EBUS) is often over-looked. Here, we present a series of 1D, 2D, and 3D numerical …
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Application of distributed measurements for finite element model verification
… The analytical results are obtained from the forced response analysis of a finite element model. A known piezoelectric actuator model that shows the actuation effects produced by symmetrically bonded actuators are line moments along the edges of the actuator and the effects produced by a …
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Active control of rotating stall in a transonic compressor stage with inlet distortion
… located upstream of the rotor tip was used for forced response testing and to extend the compressor stable operating range. Results for radial and circumferential inlet distortion are reported. First, the effects of radial distortion on the compressor performance and the dynamic behavior were …
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