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 16 of 16 for “"frequency-domain techniques"”.
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Multivariable control of a flotation plant simulator
… describes the application of two multivariable frequency domain techniques in order to design controllers for a “flotation plant”. A flotation plant simulator was designed and constructed at the University of Cape Town. The design of the multivariable controllers was based on a linear time …
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Linear and Nonlinear Modelling of Gas Turbine Engines
… with the application of modern identification techniques to model the dynamic relationship between the fuel flow and shaft speeds of a Rolls Royce aircraft gas turbine. It is motivated by the desire to exploit recent advances in modelling linear and nonlinear systems and the need to investigate …
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Exploration, processing and visualization of physiological signals from the ICU
… proposed for visualizing the data using time and frequency domain techniques. By way of a patient case study we motivate a novel method for data clustering based on the singular value decomposition and present some potential applications based on this method for use within the ICU setting.
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Identification of linear and nonlinear systems using multisine signals with a gas turbine application
Modern system identification techniques allow dynamic models to be directly estimated from measured data and the design of the data gathering experiment is a key step in any identification procedure. This thesis deals with the design of test signals for both linear and nonlinear modelling and their …
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A pseudo-optimal control approach for a redundant degree-of-freedom in a gimbaled mechanical system
… is developed, using classical time and frequency domain techniques, for comparison with the LQR controller. The quadratic weightings for the LQR controller are investigated using principles of loop shaping. Due to the time-varying nature of the linearized gimbal system, optimal gains are …
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Quantitative phonetic and frequency domain characterization of vocal blend for sung vowels
… result in quantitative changes in the frequency domain. Voice samples of two altos with choral backgrounds were collected. They sung vowels [i], [u], [el, [o], and [[alpha]] together on a D4 (293 Hz), transitioning from unblended to blended tones, and data were analyzed using frequency …
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Green's function derivations for specific acoustic admittances and impedances
… in acoustics are commonly given in their frequency-domain representations. This is done for many reasons including the simplicity of the mathematics used to compute frequency-domain impedance functions. However, although the frequency-domain representations of acoustical wave propagation …
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The state of the art time-domain wavefield imaging using a discontinuous Galerkin forward-backward time-stepping method
… Time-Stepping (FBTS) in the Time Domain (TD) is developed, employing the Discontinuous Galerkin Method (DGM) as the spatial-discretization technique. The FBTS method is based on calculating gradients of a TD cost functional with respect to the constitutive parameters of the target, …
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Experimental Identification of Nonlinear Systems
… of multiple scales is used to determine the frequency-response function for the system. Experimental frequency- and amplitude-sweep data are compared with the prediction of the frequency-response function in a least-squares curve-fitting algorithm. The algorithm is improved by making use of …
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Frequency-domain analysis of memoryless nonlinearities having large-signal, almost periodic excitations
Numerical frequency-domain techniques are widely used for the a.c. steady-state analysis of nonlinear electric circuits. Such techniques require that one compute the Fourier series for the response of each nonlinear circuit element, given a known excitation. Current approaches to this computation …
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Carbon Nitride and Conjugated Polymer Composite Materials
… at various light intensities. The use of the frequency domain techniques allowed us to separate the bulk and interfacial processes and gain valuable insight into the mechanism of losses in these devices. The results provide direct evidence that interfacial nongeminate recombination is one of …
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Condition monitoring and fault detection of inverter-fed rotating machinery
… decision-making and cost minimization. Various techniques have been extensively investigated and found to be reliable tools for the identification of faults in these machines. This thesis, however, sets out to establish a single non-invasive tool that can be used to identify the faults on all …
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Optimal filters for deconvolution of transient signals in the presence of noise
… different methods for the deconvolution of time domain signals. The techniques developed in this work are frequency domain filtering techniques. and are suitable for the type of deconvolution problems encountered in time domain reflectometry (TOR). They include a smoothing technique that is a …
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Wavelength tuneable frequency domain photon migration spectrometer for tissue-like media
Frequency domain spectrometers use intensity modulated light to quantitatively interrogate turbid media. The modulation frequencies employed are in the radiofrequency range. Intensity modulated light launched into a turbid medium generates photon density fluctuations with wave like character that …
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Characterization of Ultra Wideband Communication Channels
… in different ways using a variety of time-domain and frequency-domain techniques. The experimental setups used in channel characterization effort also include pulse generators and antennas as integral parts of the channel, since the pulse shape and antenna characteristics have significant …
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Methods of system identification, parameter estimation and optimisation applied to problems of modelling and control in engineering and physiology
… parameter estimation and optimisation techniques for model development and model validation mainly involve nonlinear continuous time models Experimentally-based models of this kind have been used very successfully in the course of the research described in this thesis very in two areas …