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 27 for “"Time varying parameters"”.
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Estimation and forecasting with time-varying parameters models and sequential method
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2026-05-01
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An improved algorithm for identification of time varying parameters using recursive digital techniques
… values for the characteristic quantities, called parameters, of a system. Examples of such quantities are mass, inductance, resistance, spring coefficient, gain, et cetera. The decreasing cost of digital processors and the versatility of digital programming make digital methods an attractive means …
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Stability and performance of time-varying adaptive systems: Analysis and applications
… and adaptive control of systems with unknown time-varying parameters, with an emphasis on obtaining performance bounds. While these issues have been extensively studied in the case of time invariant systems, time-varying systems have not received much attention. This thesis is divided into two …
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On the interaction of rate-induced and bifurcation-induced tipping in ecosystems
… by environmental changes represented by time-varying parameters [Scheffer et al. {\em Ecosystems} 11 2008]. We obtain simple criteria for tipping in terms of properties of the autonomous system with fixed in time parameters. Specifically, we use classical bifurcation analysis to identify …
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Pulse shaping techniques for mega ampere current on Atlas pulsed power machine
… a compressed pulse with a much faster rise-time for magnetic compression experiment, and another expanded current pulse with a much slower fall-time for driving very heavy liners. Comparative studies of various types of switches that can be implemented on Atlas have been examined. The …
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Sequential Calibration of Asset Pricing Models to Option Prices
… models. We estimate the latent state and parameters of the models using three non-linear filtering methods, namely the extended Kalman filter (EKF), iterated extended Kalman filter (IEKF) and the unscented Kalman filter (UKF). A simulation study is performed and the non-linear filtering …
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Revenue management models in the manufacturing industry
… depending on their sensitivity to price, lead time, and service. Specifically, we focus on identifying effective models to coordinate production, inventory and admission controls in face of multiple classes of demand and time- varying parameters. We start with a single-class-customer problem …
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An adaptive control technology for flight safety in the presence of actuator anomalies and damage
… these systems in the presence of disturbances, time-varying parameters, unmodeled dynamics, time-delays, and various nonlinearities, have been outlined in the references [4]-[13] as well as in several journal and conference papers over the same period.
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Time-varying linear prediction as a base for an isolated-word recognition algorithm
… rates; such as algorithms based on dynamic time warping, vector quantization, and other mathematical methods [l2][21][l5]. In this research, the evaluation of the feasibility of using linear prediction (LP) with time-varying parameters as a base for a voice recognition algorithm will be …
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Data-based Mechanistic Modelling (DBM) of Nonlinear Environmental Systems.
… modelling approach exploits the available time series data, in statistical terms, to expose the model structure, generating dynamic stochastic models that are parsimonious in nature and can be interpreted in a physical manner. For nonlinear systems, the DBM approach centres on the use of …
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The FitzHugh-Nagumo model dynamics with an application to the hypothalamic pituitary adrenal axis
… as bursting. I will illustrate that, by allowing time-varying parameters for the FHN model, one could overcome such limitations while still retaining the low order complexity of the FHN model. I also highlight the utility of the FHN model from an estimation perspective by presenting a novel …
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Modeling viscoelastic responses of the head/neck system during pilot ejection
… this subject, even after numerous variations of parameters controlling the head/neck response of the ATB model. Two of these parameters were determined to be time-varying for subject B9, and regression equations were developed describing the parameters as functions of time. Because the current …
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Fast learning and adaptation in control and machine learning
… these problems may include regressors which are time-varying, necessitating new algorithms in machine learning approaches as well as real-time decision making in the presence of uncertainties using adaptive control approaches. Problems of stability, fast learning with analytical guarantees, and …
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Aeroelasticity of Morphing Wings Using Neural Networks
… and linear dynamic aeroelastic systems with time varying stiffness. The use of adaptive materials in aircraft wings allows for the change of the contour or the configuration of a wing (morphing) in flight. The use of smart materials, to accomplish these deformations, can imply that the …
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Transmission of US monetary policy to the world economies. A time varying multi-country factor augmented vector autoregressive approach
… and Asian countries. For this purpose I use a time varying Factor Augmented VAR (FAVAR) model which I estimate by using Bayesian techniques. I first examine all the possible channels through which a policy shock is transmitted in each country. In general the transmission of the shock hides …
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Fast Parameter Learning in Adaptive Systems
… exposed to parametric uncertainties in real-time with guarantees of stability and control goals of tracking. A central part of adaptive control is parameter estimation. Real-time adaptive control requires parameter estimation to occur quickly and accurately. This thesis is dedicated to fast …
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Simulating Dynamical Systems from Data
… across a variety of tasks. These tasks include time series imputation and forecasting, change point detection, reinforcement learning, and trace-driven simulation in networked systems. Exploiting the principled factorization structure has paved the way for the contributions we make in different …
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Observer-Based Simultaneous States and Parameters Estimation Method with Application to System Heath Monitoring
… states of a system and the estimation of its time-varying / unknown parameters simultaneously. This twin estimation aspect is crucial for real-time system monitoring, fault diagnosis and the optimization of system control strategies. Provided in this thesis is a comprehensive review of the …
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Three essays in macroeconomic forecasting using Bayesian model selection
… several aspects of Bayesian model selection in time series forecasting of macroeconomic variables. The contribution is provided in three essays. In the first essay (Chapter 2) I forecast quarterly US inflation based on the generalized Phillips curve using econometric methods which incorporate …
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Stability Analysis of Positive Systems with Applications to Epidemiology
… forms of uncertainty: nonlinear, switched and time-delay positive systems. Our focus is on positive systems which are monotone. Naturally, monotonicity methods play a key role in obtaining our results. We start with presenting stability conditions for uncertain nonlinear positive systems. We …
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