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On gravitational wave modeling: numerical relativity data analysis, the excitation of kerr quasinormal modes, and the unsupervised machine learning of waveform morphologyLondon, Lionel 21 September 2015 (has links)
The expectation that light waves are the only way to gather information about the distant
universe dominated scientific thought, without serious alternative, until Einstein’s 1916
proposal that gravitational waves are generated by the dynamics of massive objects. Now,
after nearly a century of speculation, theoretical development, observational support, and
finally, tremendous experimental preparation, there are good reasons to believe that we will
soon directly detect gravitational waves. One of the most important of these good reasons
is the fact that matched filtering enables us to dig gravitational wave signals out of noisy
data, if we have prior information about the signal’s morphology. Thus, at the interface of
Numerical Relativity simulation, and data analysis for experiment, there is a central effort
to model likely gravitational wave signals. In this context, I present my contributions to
the modeling of Gravitational Ringdown (Kerr Quasinormal Modes). Specifically by ap-
propriately interfacing black hole perturbation theory with Numerical Relativity, I present
the first robust models for Quasinormal Mode excitation. I present the first systematic de-
scription of Quasinormal Mode overtones in simulated binary black hole mergers. I present
the first systematic description of nonlinear Quasinormal Mode excitation in simulated bi-
nary black hole mergers. Lastly, it is suggested that by analyzing the phase of black hole
Quasinormal Modes, we may learn information about the black hole’s motion with respect
to the line of sight. Moreover, I present ongoing work at the intersection of gravitational
wave modeling and machine learning. This work shows promise for the automated and near
optimal placement of Numerical Relativity simulations concurrent with the near optimal
linear modeling of gravitational output.
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Entropy Maximisation and Open Queueing Networks with Priority and Blocking.Kouvatsos, Demetres D., Awan, Irfan U. January 2003 (has links)
No / A review is carried out on the characterisation and algorithmic implementation of an extended product-form approximation, based on the principle of maximum entropy (ME), for a wide class of arbitrary finite capacity open queueing network models (QNMs) with service and space priorities. A single server finite capacity GE/GE/1/N queue with R (R>1) distinct priority classes, compound Poisson arrival processes (CPPs) with geometrically distributed batches and generalised exponential (GE) service times is analysed via entropy maximisation, subject to suitable GE-type queueing theoretic constraints, under preemptive resume (PR) and head-of-line (HOL) scheduling rules combined with complete buffer sharing (CBS) and partial buffer sharing (PBS) management schemes stipulating a sequence of buffer thresholds {N=(N1,¿,NR),0<Ni¿Ni¿1,i=2,¿,R}. The GE/GE/1/N queue is utilised, in conjunction with GE-type first two moment flow approximation formulae, as a cost-effective building block towards the establishment of a generic ME queue-by-queue decomposition algorithm for arbitrary open QNMs with space and service priorities under repetitive service blocking with random destination (RS-RD). Typical numerical results are included to illustrate the credibility of the ME algorithm against simulation for various network topologies and define experimentally pessimistic GE-type performance bounds. Remarks on the extensions of the ME algorithm to other types of blocking mechanisms, such as repetitive service blocking with fixed destination (RS-FD) and blocking-after-service (BAS), are included.
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