Spelling suggestions: "subject:"orthogonality""
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A Phan-type theorem for orthgonal [sic] groupsRoberts, Adam E. January 2005 (has links)
Thesis (Ph.D.)--Bowling Green State University, 2005. / Document formatted into pages; contains v, 73 p. Includes bibliographical references.
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Solving optimization problems with generalized orthogonality constraintsZhu, Hong 08 July 2016 (has links)
This thesis focuses on optimization problems with generalized orthogonality constraints, which may also contains linear equality constraints. These problems appear in many areas, such as machine learning, signal processing, computer vision and so on.;Many problems in this form are NP hard. One challenge posed by generalized orthogonality constraints is local minimizers loaded by nonconvex constraints. More-over, the generalized orthogonality constraints are numerically expensive to preserve during iterations.;This thesis is mainly divided into two parts. The first part is focused on solving generalized orthogonality constrained optimization problems with differentiable objective functions. For this class of optimization problems, a generalized gradient.;This thesis is mainly divided into two parts. The first part is focused on solving generalized orthogonality constrained optimization problems with differentiable objective functions. For this class of optimization problems, a generalized gradient flow is proposed, which is contained on the constraints set if the initial condition satisfies generalized orthogonality constrains. The week convergence of the generalizedgradient flow is given. A discrete iterative scheme is also proposed to make the gradient flow method computable. In addition, we analyze the relationship between our discrete iteration scheme and some existing constraint preserving methods, and the relationship between our discrete iteration scheme and the inexact forward-backward method, respectively. Several problems which also can be solved by the generalized gradient flow are given. Furthermore, we also propose an optimal gradient flow by an alyzing the first order optimality condition.;The second part of this thesis is devoted to study of the generalized orthogonality constrained optimization problems with nondifferentiable objective functions. An approximate augmented Lagrangian method is used to deal with this class of problems. The global convergence is presented. We also extend the proximal alternating linearized minimization method (EPALM) to deal with the generalized orthogonality constraints appeared in the subproblem of the approximate augmented Lagrangian method. Moreover, to accelerate the EPALM method, an inertial proximal alternating linearized minimization method (IPALM) is proposed to deal with unconstrained nonconvex, nonsmooth problems with coupled objective functions.;Keywords: Generalized Orthogonality Constraints; Stiefel Manifold; Tangent Space;Gradient Flow; Approximate Augmented Lagrangian Method; Proximal Alternating Linearized Minimization Method.
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System design and signal processing for OFDM-based wireless communication systemsLiu, Jianhua. January 2004 (has links)
Thesis (Ph. D.)--University of Florida, 2004. / Title from title page of source document. Document formatted into pages; contains 199 pages. Includes vita. Includes bibliographical references.
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Adaptive multiple access and resource allocation with guaranteed QoS for broadband OFDM wireless networks /Zhang, Yingjun. January 2004 (has links)
Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 125-129). Also available in electronic version. Access restricted to campus users.
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Typhoon motion forecasting using empirical orthogonal function analysis of the synoptic forcing/Shaffer, Alan R. January 1982 (has links)
Thesis (M.S. in Meteorology)--Naval Postgraduate School, March 1982. / Bibliography: l. 146-148. Also available online.
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Elastic Response of Acoustic Coating on Fluid-Loaded Rib-Stiffened Cylindrical ShellsDoherty, Christopher Gilles 29 June 2017 (has links)
Reinforced cylindrical shells are used in numerous industries; common examples include undersea vehicles and industrial piping. Current models typically incorporate approximate theories to determine shell behavior, which have limitations in terms of both thickness and frequency. In addition, many applications feature coatings on the shell surface that normally have thicknesses which must also be considered. To increase the fidelity of such systems, this work develops an analytical model of an elastic cylindrical shell featuring periodically spaced ring stiffeners with an acoustic coating applied to the outer surface. There is an external fluid environment. Beginning with the equations of elasticity for a solid, spatial-domain displacement field solutions are produced incorporating unknown wave propagation coefficients. These fields are used to determine stresses at the boundaries of the shell and coating, which are then coupled with stresses from the stiffeners and fluid. The stress boundary conditions contain double-index infinite summations, which are decoupled, truncated, and recombined into a global matrix equation. The solution to this global equation results in the displacement responses of the system as well as the scattered pressure field. Two distinct loadings are considered: a ring loading and an incident acoustic wave. Thin-shell reference models are used for validation, and the acoustic response of the system is examined. It is shown that the reinforcing ribs and acoustic coating have a considerable effect on system behavior. / Master of Science / Reinforced cylindrical shells are used in numerous industries; common examples include undersea vehicles and industrial piping. Current models typically incorporate approximate theories to determine shell behavior, which have limitations in terms of both thickness and frequency. In addition, many applications feature coatings on the shell surface that normally have thicknesses which must also be considered. To increase the fidelity of such systems, this work develops an analytical model of an elastic cylindrical shell featuring periodically spaced ring stiffeners with an acoustic coating applied to the outer surface. There is an external fluid environment. Beginning with elastic equations of motion for a solid, the displacements of the system can be found. These displacements are used to determine stresses at the boundaries of the shell and coating, which are then coupled with stresses from the stiffeners and fluid. Techniques are used to transform the stress boundary conditions into a large matrix equation, and the solution to this global equation results in the displacement responses of the system as well as the scattered pressure field. Two distinct loadings are considered: a ring loading and an incident acoustic wave. Thin-shell reference models are used for validation, and the acoustic response of the system is examined. It is shown that the reinforcing ribs and acoustic coating have a considerable effect on system behavior.
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Super-orthogonal space-time turbo coded OFDM systems.Oluwafemi, Ilesanmi Banjo. January 2012 (has links)
The ever increasing demand for fast and efficient broadband wireless communication
services requires future broadband communication systems to provide a high data rate,
robust performance and low complexity within the limited available electromagnetic
spectrum. One of the identified, most-promising techniques to support high
performance and high data rate communication for future wireless broadband services
is the deployment of multi-input multi-output (MIMO) antenna systems with
orthogonal frequency division multiplexing (OFDM). The combination of MIMO and
OFDM techniques guarantees a much more reliable and robust transmission over a
hostile wireless channel through coding over the space, time and frequency domains.
In this thesis, two full-rate space-time coded OFDM systems are proposed. The first
one, designed for two transmit antennas, is called extended super-orthogonal space-time
trellis coded OFDM (ESOSTTC-OFDM), and is based on constellation rotation. The
second one, called super-quasi-orthogonal space-time trellis coded OFDM (SQOSTTCOFDM),
combines a quasi-orthogonal space-time block code with a trellis code to
provide a full-rate code for four transmit antennas. The designed space-time coded
MIMO-OFDM systems achieve a high diversity order with high coding gain by
exploiting the diversity advantage of frequency-selective fading channels.
Concatenated codes have been shown to be an effective technique of achieving reliable
communication close to the Shannon limit, provided that there is sufficient available
diversity. In a bid to improve the performance of the super orthogonal space-time
trellis code (SOSTTC) in frequency selective fading channels, five distinct
concatenated codes are proposed for MIMO-OFDM over frequency-selective fading
channels in the second part of this thesis. Four of the coding schemes are based on the
concatenation of convolutional coding, interleaving, and space-time coding, along
multiple-transmitter diversity systems, while the fifth coding scheme is based on the
concatenation of two space-time codes and interleaving. The proposed concatenated
Super-Orthogonal Space-Time Turbo-Coded OFDM System I. B. Oluwafemi 2012 vii
coding schemes in MIMO-OFDM systems achieve high diversity gain by exploiting
available diversity resources of frequency-selective fading channels and achieve a high
coding gain through concatenations by employing the turbo principle. Using computer
software simulations, the performance of the concatenated SOSTTC-OFDM schemes is
compared with those of concatenated space-time trellis codes and those of conventional
SOSTTC-OFDM schemes in frequency-selective fading channels. Simulation results
show that the concatenated SOSTTC-OFDM system outperformed the concatenated
space-time trellis codes and the conventional SOSTTC-OFDM system under the
various channel scenarios in terms of both diversity order and coding gain. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2012.
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On O-basis groups and generalizationsErvin, Jason January 2007 (has links) (PDF)
Thesis (Ph.D.)--Auburn University, 2007. / Abstract. Includes bibliographic references (ℓ. 68)
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Restarting the Lanczos algorithm for large eigenvalue problems and linear equationsNicely, Dywayne A. Morgan, Ronald Benjamin, January 2008 (has links)
Thesis (Ph.D.)--Baylor University, 2008. / Includes bibliographical references (p. 70-74)
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Optimal resource allocation algorithm with QoS and fairness supported for SDMA OFDM system /Tsang, Yui Ming. January 2004 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 63-66). Also available in electronic version. Access restricted to campus users.
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