Dissertations / Theses: 'Spectral analysis'

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Sendov, Hristo. "Variational Spectral Analysis." Thesis, University of Waterloo, 2000. http://hdl.handle.net/10012/1089.

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We present results on smooth and nonsmooth variational properties of {it symmetric} functions of the eigenvalues of a real symmetric matrix argument, as well as {it absolutely symmetric} functions of the singular values of a real rectangular matrix. Such results underpin the theory of optimization problems involving such functions. We answer the question of when a symmetric function of the eigenvalues allows a quadratic expansion around a matrix, and then the stronger question of when it is twice differentiable. We develop simple formulae for the most important nonsmooth subdifferentials of functions depending on the singular values of a real rectangular matrix argument and give several examples. The analysis of the above two classes of functions may be generalized in various larger abstract frameworks. In particular, we investigate how functions depending on the eigenvalues or the singular values of a matrix argument may be viewed as the composition of symmetric functions with the roots of {it hyperbolic polynomials}. We extend the relationship between hyperbolic polynomials and {it self-concordant barriers} (an extremely important class of functions in contemporary interior point methods for convex optimization) by exhibiting a new class of self-concordant barriers obtainable from hyperbolic polynomials.

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Collins, Brian Harris. "Thermal imagery spectral analysis." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA320553.

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Thesis (M.S. in Systems Technology (Space Systems Operations)) Naval Postgraduate School, September 1996.
Thesis advisor(s): R.C. Olsen, David Cleary. "September 1996." Includes bibliographical references (p. 159-161). Also available online.

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de, Roos Dolf. "Spectral analysis classification sonars." Thesis, University of Canterbury. Electrical Engineering, 1986. http://hdl.handle.net/10092/5575.

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Sonar target classification based on frequency-domain echo analysis is investigated. Conventional pulsed sonars are compared with continuous transmission frequency modulated (CTFM) sonars, and differences relating to target classification are discussed. A practical technique is introduced which eliminates the blind time inherent in CTFM technology. The value and implications of modelling underwater sonars in air are discussed and illustrated. The relative merits of auditory, visual and computer analysis of echoes are examined, and the effects of using two or more analysis methods simultaneously are investigated. Various statistical techniques for detecting and classifying targets are explored. It is seen that with present hardware limitations, a two-stage echo analysis approach offers the most efficient means of target classification. A novel design for three-section quarter-wavelength transducers is presented and evaluated. Their inherently flat frequency response makes these transducers well suited to broadband applications. The design philosophy and construction details of a Diver's Sonar and an underwater Classification Sonar are given. Sea trials reveal that using the Diver's Sonar, a blind-folded diver can successfully navigate in an unknown environment, and locate and classify targets; using the Classification Sonar, targets may be located and classified using either operators or computer software.

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Hu, Zhihua. "Spectral fatigue analysis techniques." Thesis, University College London (University of London), 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362446.

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Cannon, Robert William. "Automated Spectral Identification of Materials using Spectral Identity Mapping." Cleveland State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=csu1377031729.

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Youatt, Andrew Pierce. "Analyzing Edgard Varese's Ionisation Using Digital Spectral Analysis." Thesis, The University of Arizona, 2012. http://hdl.handle.net/10150/232473.

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Although Robert Cogan's New Images of Musical Sound won the Society of Music Theory's Outstanding Publication Award in 1987, his musical application of spectral analysis has seen little use over the past 25 years. Spectral images are most effective at illustrating the timbre of sound, and harmony, not timbre, is the key structural component of most Western music. There are, however, some compositions in which timbre plays a critical role. Chief among these is Edgard Varèse's Ionisation, an epic percussion ensemble piece built around 40 instruments and 13 musicians. Previous analyses by Jean-Charles François and Varèse protege Chou Wen-Chung have emphasized the importance of timbre to Ionisation's construction, but are limited in their exploration of timbral qualities. Modern digital spectral analysis allows for a more accurate picture of the individual timbres that make up Ionisation and define the broader textures and structures that give the piece meaning.

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Moreira-Paredes, Ramiro. "Nontraditional windows in spectral analysis." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA271336.

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Jamieson, Gary. "Spectral analysis of pulmonary sounds." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240595.

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Bandtlow, Oscar F. "Spectral analysis of dynamical systems." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396095.

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Nastov, Ognen J. (Ognen Jovan). "Spectral methods for circuit analysis." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/16718.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.
Includes bibliographical references (p. 119-124).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Harmonic balance (HB) methods are frequency-domain algorithms used for high accuracy computation of the periodic steady-state of circuits. Matrix-implicit Krylov-subspace techniques have made it possible for these methods to simulate large circuits more efficiently. However, the harmonic balance methods are not so efficient in computing steady-state solutions of strongly nonlinear circuits with rapid transitions. While the time-domain shooting-Newton methods can handle these problems, the low-order integration methods typically used with shooting-Newton methods are inefficient when high solution accuracy is required. We first examine possible enhancements to the standard state-of-the-art preconditioned matrix-implicit Krylovsubspace HB method. We formulate the BDF time-domain preconditioners and show that they can be quite effective for strongly nonlinear circuits, speeding up the HB runtimes by several times compared to using the frequency-domain block-diagonal preconditioner. Also, an approximate Galerkin HB formulation is derived, yielding a small improvement in accuracy over the standard pseudospectral HB formulation, and about a factor of 1.5 runtime speedup in runs reaching identical solution error. Next, we introduce and develop the Time-Mapped Harmonic Balance method (TMHB) as a fast Krylov-subspace spectral method that overcomes the inefficiency of standard harmonic balance for circuits with rapid transitions. TMHB features a non-uniform grid and a time-map function to resolve the sharp features in the signals. At the core of the TMHB method is the notion of pseudo Fourier approximations. The rapid transitions in the solution waveforms are well approximated with pseudo Fourier interpolants, whose building blocks are complex exponential basis functions with smoothly varying frequencies. The TMHB features a matrix-implicit Krylov-subspace solution approach of same complexity as the standard harmonic balance method. As the TMHB solution is computed in a pseudo domain, we give a procedure for computing the real Fourier coefficients of the solution, and we also detail the construction of the time-map function. The convergence properties of TMHB are analyzed and demonstrated on analytic waveforms. The success of TMHB is critically dependent on the selection of a non-uniform grid. Two grid selection strategies, direct and iterative, are introduced and studied. Both strategies are a priori schemes, and are designed to obey accuracy and stability requirements. Practical issues associated with their use are also addressed. Results of applying the TMHB method on several circuit examples demonstrate that the TMHB method achieves up to five orders of magnitude improvement in accuracy compared to the standard harmonic balance method. The solution error in TMHB decays exponentially faster than the standard HB method when the size of the Fourier basis increases linearly. The TMHB method is also up to six times faster than the standard harmonic balance method in reaching identical solution accuracy, and uses up to five times less computer memory. The TMHB runtime speedup factor and storage savings favorably increase for stricter accuracy requirements, making TMHB well suited for high accuracy simulations of large strongly nonlinear circuits with rapid transitions.
by Ognen J. Nastov.
Ph.D.

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Smith, Natalie T. (Natalie Tamika) 1978. "Interactive spectral analysis learning module." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8600.

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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.
Includes bibliographical references (leaf 103).
Due to increased demand for interactive learning opportunities for engineering students, an interactive spectral analysis learning module was developed for the course Biomedical Signal and Image Processing (HST582J/6.555J/16.456J). The design of this module is based on the Star Legacy model, a pedagogical framework that promotes the creation of guided learning environments that use applications as the context for focused learning activities. The module is implemented using a combination of traditional teaching methods and web-based components. The web-based components include tutorial questions, text summaries, tables, figures, a glossary, and an interactive demonstration. This module was used in HST582J/6.555J/16.456J during Spring Term 2001. A variety of assessment techniques were employed. Survey results show that students generally found the module useful. Student performance on lab reports showed improved understanding of key concepts relative to previous years. Future efforts should reanalyze other performance data and make suggested modifications to the overall module, the web-based tutorial, and the interactive demo.
by Natalie T. Smith.
M.Eng.

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Mugglestone, Moira A. "Spectral analysis of spatial processes." Thesis, University of Edinburgh, 1990. http://hdl.handle.net/1842/15450.

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This thesis is concerned with the development of two-dimensional spectral analysis as a technique for investigating spatial pattern, and the stochastic processes which generate pattern. The technique is discussed for two types of data: first, quantitative measurements associated with a rectangular grid, or lattice; secondly, analysis of spatial point patterns using the coordinates which describe the locations of events. Spectral analysis of lattice data is applied to two examples of remotely sensed digital imagery. The first example consists of digitised aerial photographs of glaciated terrain in Canada. Spectral analysis is used to detect geological lineations which are visible in the photographs, and to study the structure of the land surface beneath the lineations. The second example is meteorological satellite imagery. Spectral analysis is used to develop a system for discrimination between different cloud types. Point spectral analysis is used as the basis of formal tests for randomness, against alternatives such as clustering or inhibition. Spectral theory for univariate spatial point patterns is extended to cross-spectral analysis of bivariate point patterns. In particular, we show how cross-spectral functions indicate the type of interaction between the events of two patterns. A test for independent components is composed, and the application of the test is demonstrated using a variety of real and artificial patterns. A further extension, to bispectral analysis of third-order properties of spatial point patterns, is also discussed. This type of analysis is used to distinguish between processes which have the same first- and second-order properties, but different third-order properties. Finally, we show how Greig-Smith analysis of quadrant count data can be interpreted as a type of two-dimensional spectral analysis based on a set of orthogonal square waves known as Walsh functions. This representation indicates why Greig Smith's method is entirely dependent on the starting point of the grid.

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Shorten, David. "Spectral analysis of neutral evolution." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27420.

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It has been argued that much of evolution takes place in the absence of fitness gradients. Such periods of evolution can be analysed by examining the mutational network formed by sequences of equal fitness, that is, the neutral network. It has been demonstrated that, in large populations under a high mutation rate, the population distribution over the neutral network and average mutational robustness are given by the principal eigenvector and eigen- value, respectively, of the network's adjacency matrix. However, little progress has been made towards understanding the manner in which the topology of the neutral network influences the resulting population distribution and robustness. In this work, we build on recent results from spectral graph theory and utilize numerical methods to enhance our understanding of how populations distribute themselves over neutral networks. We demonstrate that, in the presence of certain topological features, the population will undergo an exploration catastrophe and become confined to a small portion of the network. We further derive approximations, in terms of mutational biases, for the population distribution and average robustness in networks with a homogeneous structure. The applicability of these results is explored, first, by a detailed review of the literature in both evolutionary computing and biology concerning the structure of neutral networks. This is extended by studying the actual and predicted population distribution over the neutral networks of H1N1 and H3N2 influenza haemagglutinin during seasons between 2005 and 2016. It is shown that, in some instances, these populations experience an exploration catastrophe. These results provide insight into the behaviour of populations on neutral networks, demonstrating that neutrality does not necessarily lead to an exploration of genotype/phenotype space or an associated increase in population diversity. Moreover, they provide a plausible explanation for conflicting results concerning the relationship between robustness and evolvability.

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Salzman, Julia. "Spectral analysis with Markov chains /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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Smirnov, Stanislav K. Makarov Nicolai G. "Spectral analysis of Julia sets /." Diss., Pasadena, Calif. : California Institute of Technology, 1996. http://resolver.caltech.edu/CaltechETD:etd-09152006-144938.

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McSherry, Frank. "Spectral methods for data analysis /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/7004.

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LIMA, MAURO VIEIRA DE. "SPECTRAL OCCUPANCY MEASUREMENT AND SPECTRAL OPPORTUNITIES ANALYSIS TO COGNITIVE RADIO SYSTEMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2013. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=21955@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
Atualmente, a escassez espectral é um problema real que está sendo agravado pela alta demanda de sistemas de banda larga sem fio. A tecnologia do rádio cognitivo tem sido considerada uma solução promissora para esse problema. Muitas campanhas de medição de espectro, cobrindo uma larga faixa de frequências e outras em bandas específicas, têm sido desenvolvidas em diversos locais e cenários para determinar o grau de ocupação do espectro alocado em ambientes reais de sistemas de comunicação sem fio. Medições de ocupação do ambiente radioelétrico podem prover importantes informações sobre o uso atual do espectro. Estas informações são importantes para a definição adequada de políticas de uso dinâmico do espectro, seleção apropriada de faixas de frequências para implementação de futuras redes de rádios cognitivos e identificação de padrões de uso que podem ser explorados no desenvolvimento de modelos e técnicas de uso eficiente do espectro.
Currently, spectrum scarcity is a real problem that is being worsened by the high demand for wireless broadband systems. The technology of cognitive radio has been considered a promising solution to this problem. Many spectrum measurement campaigns, covering a wide band of frequencies, and also specific bands, have been developed in several locations and sceneries for determining the degree of occupation of the allocated spectrum in real environments of wireless communication systems. Occupation measurements of radio spectrum environment can provide important information about the current use of the spectrum. This information is important for suitable policies definition for dynamic use of the spectrum, for frequency bands selection to implement future cognitive radio networks and for patterns identification that can be exploited in the development of models and techniques for efficient use of spectrum.

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Chowdhury, Subir. "Development of a spectral unmixing procedure using a genetic algorithm and spectral shape." Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Geography, c2012, 2012. http://hdl.handle.net/10133/3345.

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Spectral unmixing produces spatial abundance maps of endmembers or ‘pure’ materials using sub-pixel scale decomposition. It is particularly well suited to extracting a greater portion of the rich information content in hyperspectral data in support of real-world issues such as mineral exploration, resource management, agriculture and food security, pollution detection, and climate change. However, illumination or shading effects, signature variability, and the noise are problematic. The Least Square (LS) based spectral unmixing technique such as Non-Negative Sum Less or Equal to One (NNSLO) depends on “shade” endmembers to deal with the amplitude errors. Furthermore, the LS-based method does not consider amplitude errors in abundance constraint calculations, thus, often leads to abundance errors. The Spectral Angle Constraint (SAC) reduces the amplitude errors, but the abundance errors remain because of using fully constrained condition. In this study, a Genetic Algorithm (GA) was adapted to resolve these issues using a series of iterative computations based on the Darwinian strategy of ‘survival of the fittest’ to improve the accuracy of abundance estimates. The developed GA uses a Spectral Angle Mapper (SAM) based fitness function to calculate abundances by satisfying a SAC-based weakly constrained condition. This was validated using two hyperspectral data sets: (i) a simulated hyperspectral dataset with embedded noise and illumination effects and (ii) AVIRIS data acquired over Cuprite, Nevada, USA. Results showed that the new GA-based unmixing method improved the abundance estimation accuracies and was less sensitive to illumination effects and noise compared to existing spectral unmixing methods, such as the SAC and NNSLO. In case of synthetic data, the GA increased the average index of agreement between true and estimated abundances by 19.83% and 30.10% compared to the SAC and the NNSLO, respectively. Furthermore, in case of real data, GA improved the overall accuracy by 43.1% and 9.4% compared to the SAC and NNSLO, respectively.
xvi, 85 leaves : ill. (chiefly col.) ; 29 cm

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Shortreed, Susan. "Learning in spectral clustering /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8977.

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Ajohani, Maha. "SPECTRAL PHASOR ANALYSIS ON ABSORBANCE SPECTRA FOR QUANTIFYING THE CONTENT OF DYE MIXTURES." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1464191406.

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Vowels, Matthew James. "THE APPLICATION OF SPECTRAL AND CROSS-SPECTRAL ANALYSIS TO SOCIAL SCIENCES DATA." UKnowledge, 2018. https://uknowledge.uky.edu/hes_etds/58.

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The primary goal of this paper is to demonstrate the application of a relatively esoteric and interdisciplinary technique, called spectral analysis, to dyadic social sciences data. Spectral analysis is an analytical and statistical technique, commonly used in engineering, that allows times series data to be analyzed for the presence of significant regular/periodic fluctuations/oscillations. These periodic fluctuations are reflected in the frequency domain as amplitude or energy peaks at certain frequencies. Furthermore, a Magnitude Squared Coherence analysis may be used to interrogate more than one time series concurrently in order to establish the degree of frequency domain correlation between the two series, as well to establish the phase (lead/lag) relationship between the coherent frequency components. In order to demonstrate the application of spectral analysis, the current study utilizes a secondary dyadic dataset comprising 30 daily reports of perceived sexual desire for 65 couples. The secondary goal of this paper is to establish a) whether there is significant periodic fluctuation in perceived levels of sexual desire for men and/or women, and at which specific frequencies, and b) how much correlation or `cross-spectral coherence' there is between partners' sexual desire within the dyads, and c) what the phase lead-lag relationship is between the partners at any of the identified frequency components. Sexual desire was found to have significant periodic components for both men and women, with a fluctuation of once per month being the most common frequency component across the groups of individuals under analysis. Mathematical models are presented in order to describe and illustrate these principal fluctuations. Partners in couples, on average, were found to fluctuate together at a number of identified frequencies, and the phase lead/lag relationships of these frequencies are presented.

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Carter, Nancy J. Loomis H. H. Bernstein Raymond F. Jr. "Implementation of cyclic spectral analysis methods." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School; Available from the National Technical Information Service, 1992. http://handle.dtic.mil/100.2/ADA261715.

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Völcker, Björn. "Performance Analysis of Parametric Spectral Estimators." Doctoral thesis, KTH, Signals, Sensors and Systems, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3323.

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Altintepe, Hakan. "A spectral analysis of nonequiprobable signalling." Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/5946.

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In this thesis, a review of the fundamentals of the shaping codes and trellis shaping methods is provided. This analysis begins with a consideration of the spectral properties of memoryless modulation producing nonequiprobable signalling. Then, spectral properties of two examples of signals from shaping codes and sixteen examples of trellis shaping are numerically analyzed. It was found that the statistics of the signal points affect the power spectrum of the coded output signal. Yet, if certain symmetry rules are obeyed in design of the transmission system, such that a 90$\sp\circ$ rotational symmetric constellation (180$\sp\circ$ symmetric for QAM signalling) is combined with any linear error correcting code, the power spectrum of the output signal sequence can be made invariant to the changes in the statistics of the signal points. These symmetry rules relate to the geometrical symmetry of the signal points. These symmetry rules relate to the geometrical symmetry of the signal constellation and to the linearity of the codes used in communications system. Consequently, it has been verified that shaping gain can be achieved by nonequiprobable signalling without an expansion in the transmission bandwidth. (Abstract shortened by UMI.)

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Sundin, Tomas. "Spectral analysis and magnetic resonance spectroscopy /." Uppsala : Uppsala University, 2001. http://www.gbv.de/dms/goettingen/329752413.pdf.

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Estebane, Caleb Antonio Rascon. "Spectral component analysis on distorted data." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506276.

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Fridriksson, Joel Karl. "Spectral analysis of X-ray binaries." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/77486.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references.
In this thesis, I present work from three separate research projects associated with observations of X-ray binaries. Two of those revolve around spectral characteristics of neutron star low-mass X-ray binaries (NS-LMXBs), with a particular source, XTE J1701-462, playing a central role. First, I construct and study color-color and hardness-intensity diagrams (CDs and HIDs) for a large sample of NS-LMXBs using Rossi X-ray Timing Explorer (RXTE) data spanning ~15 years. I study in particular detail three sources whose complicated CDs/HIDs are strongly affected by secular motion -- Cyg X-2, Cir X-1, and GX 13+1 -- and show that Cyg X-2 and Cir X-1 display CD/HID evolution with strong similarities to the transient Z source XTE J1701-462, which was previously shown to have evolved through all subclasses of NS-LMXBs as a result of changes in mass accretion rate. I build on the results for XTE J1701-462, Cyg X-2, and Cir X-1 and rank all the sources in the sample based only on their CD/HID morphology. I speculate that this represents a rough ranking in terms of the relative ranges in mass accretion rate experienced by the sources. Next, I use data from RXTE, Swift, Chandra, and XMM-Newton to study the transition to quiescence and the first ~1200 days of the quiescent phase of XTE J1701-462 following the end of its extraordinarily luminous 19 month outburst in 2006-2007. I find that the crust of the neutron star cooled rapidly during the first ~200 days of quiescence, after having been heated out of thermal equilibrium with the core during the outburst; the source has subsequently shown slower cooling along with sporadic low-level accretion activity. I discuss the implications of the observed cooling behavior and low-level accretion, the former of which yields information on the internal properties of the neutron star. Finally, I use multiple Chandra observations to study the X-ray source populations in the late-type galaxies NGC 6946 and NGC 4485/4490. A particular emphasis is placed on investigating the long-term variability of the sources, several of which are ultraluminous. I present detailed source catalogs and characterize the populations -- which consist primarily of X-ray binaries -- using X-ray luminosity functions and CDs.
by Joel Karl Fridriksson.
Ph.D.

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Zhang, Yuqing M. Eng Massachusetts Institute of Technology. "Spectral analysis of high-frequency finance." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106399.

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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 73-76).
Popular across a wide range of fields, spectral analysis is a powerful technique for studying the behavior of complex systems. It decomposes a signal into many different periodic components, each associated with a specific cycle length. We argue that the application of spectral analysis to finance leads to natural interpretations in terms of horizon-specific behaviors. A spectral framework provides a few main advantages over conventional time domain approaches to financial analysis: (1) improved computational efficiency for the evaluation of behaviors across a spectrum of time horizons, (2) reduced vulnerability to aliasing effects, and (3) more convenient representations of inherently cyclic dynamics, e.g. business cycles, credit cycles, liquidity cycles, etc. In this paper we first present a set of spectral techniques, including a frequency-specific correlation and a frequency decomposition of trading strategy profits. Then, we demonstrate the application of these techniques in an empirical analysis of high-frequency dynamics over the years 1995-2014. Our results consist of three parts: (1) an analysis of individual stock returns and various portfolio returns, (2) an analysis of contrarian trading strategies and the introduction of a novel technique for managing frequency exposures of general strategies, and (3) a case analysis of recent market shocks. The great extent to which our empirical results align with financial intuition attests to the practicality of spectral approaches to financial analysis. It demonstrates that many real phenomena can be captured through a spectral lens.
by Yuqing Zhang.
M. Eng.

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Kim, Dongyoung M. Eng Massachusetts Institute of Technology. "Spectral factor model and risk analysis." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106115.

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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 69-70).
In this paper, we apply spectral analysis tools to portfolio management. Recognizing volatility and factor beta as major risk sources, we analyze the short-term and longterm components of risk for any given portfolio. We model the portfolio weights as an LTI system filter and describe how the risk metrics behave as one holes the portfolio over increasing horizon. Then, we propose dynamic portfolios to shift frequency-specific risks without changing the investment period or net dollar exposure.
by Dongyoung Kim.
M. Eng.

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Gutiérrez, Avendaño Claudia Patricia. "Spectral analysis of Type II Supernovae." Tesis, Universidad de Chile, 2016. http://repositorio.uchile.cl/handle/2250/141777.

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Doctor en Ciencias, Mención Astronomía
La idea principal de esta tesis es el análisis de los espectros ópticos de las supernovas de tipo II (SNs II) y sus correlaciones con los parámetros fotométricos. Este análisis se basa en la caracterización de la diversidad espectral y el uso de esta para entender de una mejor forma los mecanismos físicos que involucran a las SNs II. Un objetivo clave es vincular la evolución transitoria a las propiedades del progenitor antes de la explosión. Para este propósito utilizo 893 espectros ópticos (entre 3 y 363 días) de 123 SNs II que se obtuvieron entre 1986 y 2009. Con el fin de comparar consistentemente las propiedades observadas de las SNs II, es necesario tener una época común. Para ello, estimo las fechas de explosión usando imágenes antes de la explosión y del descubrimiento y la técnica de ajuste espectral, los cuales muestran muy buenos resultados. Centrándome en el perfil P-Cygni de Hα , encuentro que SNs con menor componente de absorción con respecto a la emisión (valores pequeños en a/e), son más brillantes en el máximo, tienen una tasa de declinación más rápida en las curvas de luz, duraciones más cortas en la fase opticamente gruesa y velocidades de expansión más altas. Teniendo en cuenta estos resultados, sugiero que las diferencias entre las SNs de rápido declive (IIL) y las SNs con meseta (IIP) están relacionados con la masa de la envoltura de hidrógeno al momento de la explosión. Expandiendo el análisis a la cobertura total de los espectros, analizo la aparición de las líneas de Fe II y su evolución con el tiempo con respecto a las diferencias en a/e y la velocidad de Hα en una época dada, la magnitud en el máximo, la la tasa de declive, y la metalicidad del medio. Especulo que la evolución de líneas podría indicar diferencias en las temperaturas y/o metalicidad. Además, encuentro un componente adicional de absorción en el lado azul de Hα . Concluyo de que este componente en los espectros tempranos está asociado a Si II λ6355, mientras que en la fase de la meseta está relacionado con una característica de alta velocidad en las líneas de hidrógeno, las cuales podrían indicar señales de interacción entre el material expulsado y el viento de la supergigante roja. Por otro lado, la presencia de Si II podría estar relacionada con el radio progenitor. Analizando las propiedades espectrales y sus correlaciones con parámetros fotométricos, encuentro que SNs con velocidades más altas son más brillantes, tienen seudo-anchos equivalentes más pequeños, tasas de declive más rápidas, duraciones más cortas en la fase opticamente gruesa y en la meseta y masas de niquel más altas. Relacionando estos parámetros con las propiedades físicas de la explosión y del progenitor, especulo que la duración de la meseta está relacionado con la masa de la envoltura de hidrógeno, la tasa de declive en la curva de luz está relacionada con el radio del progenitor, y las velocidades de expansión del material expulsado con la energía de la explosión.

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31

Kohli, Meenakshi. "Spectral Variability Analysis of BL Lacertae." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1343698887.

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32

Stewart, Shannon Thomas. "Spectral analysis for rod formation dynamics." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-12172008-063238/.

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33

Wester, Roderick C. "Multidimensional spectral estimation using iterative methods." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA237025.

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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 1990.
Thesis Advisor(s): Therrien, Charles W. ; Tummala, Murali. "June 1990." Description based on title screen as viewed on October 15, 2009. DTIC Identifier(s): Iterations, Covariance, Regression Analysis, Estimates. Author(s) subject terms: Autoregressive Spectral Estimation, Covariance Method. Includes bibliographical references (p. 35). Also available in print.

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34

Meng, Xiangxiang. "Spectral Bayesian Network and Spectral Connectivity Analysis for Functional Magnetic Resonance Imaging Studies." UNIVERSITY OF CINCINNATI, 2012. http://pqdtopen.proquest.com/#viewpdf?dispub=3491383.

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35

Meng, Xiangxiang. "Spectral Bayesian Network and Spectral Connectivity Analysis for Functional Magnetic Resonance Imaging Studies." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1320681959.

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36

Le, Cras Claire. "Spectral analysis of galaxies in the ultraviolet." Thesis, University of Portsmouth, 2017. https://researchportal.port.ac.uk/portal/en/theses/spectral-analysis-of-galaxies-in-the-ultraviolet(0cd85551-3ff9-4fe9-8ec4-a26d3104d52b).html.

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Galaxy SEDs contain a wealth of information about their stellar populations with the UV region tracing their hot component. In young populations this hot component comes from luminous O and B-type stars whereas, in old populations a hot component can be produced after sufficient mass loss, a phenomenon known as the UV upturn. The UV region of galaxies remains relatively unexplored and models lack calibration due to the paucity of observational data. However, by investigating features seen in the UV region it may be possible to explore both types of population with the potential to find indicators that can differentiate between the two. I use a large sample (∼ 275,000) of z ≥ 0.6 massive (log(M_∗/M_⊙) >∼ 11) galaxies taken from the Sloan Digital Sky Survey (SDSS) - III Baryon Oscillation Spectroscopic Survey (BOSS). I use both individual spectra and stacks and employ a suite of models including a UV contribution from old populations, spanning various effective temperatures, fuel consumptions, and metallicities. By investigating the effect of the UV upturn on the strength of mid-UV indices I find a subset that are able to differentiate between old and young UV ages; Mg I, Fe I, and BL3096. I find evidence for old stars contributing to the UV in massive galaxies, rather than star formation. The data favour models with low/medium upturn temperatures (10,000 - 25,000K) consistent with local galaxies, depending on the assumed metallicity, and with a larger fuel ( f ∼ 6.5 · 10⁻²M_⊙). Models with only one temperature are favoured over models with a temperature range, which would be typical of an extended horizontal branch. Old UV-bright populations are found in the whole working sample (92%), with a mass fraction peaking around 10 - 20%. Upturn galaxies are massive and have redder colours, in agreement with findings in the local Universe. I find that the upturn phenomenon appears at z ∼ 1 and its frequency increases towards lower redshift, as expected by the stellar evolution of low mass stars. These findings will help to constrain stellar evolution in the little explored UV upturn phase. The highest redshift galaxies are young and hence exhibit a pronounced UV spectrum due to their massive star components. The UV rest-frame is also what is actually sampled via optical and near-IR observations at these high redshifts. However, a comprehensive study of UV absorption lines, which may provide useful indicators for physical properties such as stellar age and metallicity, is still lacking. I exploit stellar population models of absorption line indices in the far-UV (1200 - 1900Å) to study the spectra of young high-z galaxies. Using high-z spectra from Sommariva et al. (2012), Erb et al. (2010), and VVDS, the central aim of this analysis is to assess the ability of the model indices to recover the stellar ages and metallicities found in the literature. Using a set of far-UV indices I fit both SSPs and CSPs to the strength of the absorption features found in the data as well as fitting the full far-UV spectral region. A simple test using mock galaxies shows the effect of dust to be negligible when fitting the indices in combination however, there may be more complicated effects that are not modelled well. The analysis shows that currently it is not possible to reliably derive the stellar ages or metallicities of high-z galaxies using the methods explored in this work. The large range of χ² values for the model fitting is likely due to the errors of the spectral indices being underestimated and the low quality of the UV data. However, issues may also lie on the model side. Emission lines are known to effect the far-UV region and could contaminate the absorption features investigated in this work. The spectra analysed have not been "cleaned" of emission lines and such features are not included in theoretical modelling.

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Rozario, Hoimonti Immaculata. "Spectroscopic study of acetylene and hydrogen cyanide." Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Physics and Astronomy, c2012, 2012. http://hdl.handle.net/10133/3415.

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High-resolution molecular spectroscopy has been used to study acetylene line parameters and emission spectra of hydrogen cyanide. All acetylene spectra were recorded in our laboratory at the University of Lethbridge using a 3-channel tuneable diode laser spectrometer. N2-broadened line widths and N2-pressure induced line shifts have been measured for transitions in the v1+v3 band of acetylene at seven temperatures in the range 213–333K to obtain the temperature dependences of broadening and shift coefficients. The Voigt and hard-collision line profile models were used to retrieve the line parameters. The line-broadening and line-shift coefficients as well as their temperature-dependent parameters have been also evaluated theoretically, in the frame work of a semi-classical approach based on an exponential representation of the scattering operator, an intermolecular potential composed of electrostatic quadrupole–quadrupole and pairwise atom–atom interactions as well as on exact trajectories driven by an effective isotropic potential. The experimental results for both N2-broadening and shifting show good agreement with the theoretical results. We have studied the line intensities of the 1νl20←0νl20 band system from the HCN emission spectrum. The infrared emission spectrum of H12C14N was measured at the Justus-Liebig University, Giessen, Germany. The emission spectrum was analyzed with the spectrum analysis software Symath running using Mathematica as a platform. This approach allowed us to retrieve information on band intensity parameters.
viii, 112 leaves : ill. ; 29 cm

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38

Kanaan, Mona N. "Cross-spectral analysis for spatial point-lattice processes." Thesis, [n.p.], 2000. http://dart.open.ac.uk/abstracts/page.php?thesisid=94.

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Magnani, Federico. "Analysis of aircraft cirrus clouds spectral measurements." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019.

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In questa tesi vengono descritte le proprietà dell’atmosfera terrestre nel lontano infrarosso (FIR) e il loro impatto climatico. Negli ultimi anni sempre più attenzione è stata posta nella ricerca in questo campo e sono stati sviluppati strumenti e metodi di analisi innovativi, come dimostrato dalla nascita della missione Far-infrared-Outgoing-Radiation Understanding and Monitoring (FORUM) che propone il lancio di un satellite attrezzato con strumenti FIR. Quasi il 45% dell’energia emessa dal pianeta è portata da onde nel FIR, attraverso il meccanismo del trasferimento radiativo: poichè l’atmosfera è per lo più trasparente alla luce visibile proveniente dal Sole, ma non alla radazione infrarossa proveniente dalla superficie del pianeta, l’emissione netta nello spazio è rallentata. Il trasferimento dell’energia in atmosfera dipende, oltre che da variabili termodamiche, dalla lunghezza d’onda considerata, per via dell’elevata complessità dello spettro atmosferico: essendo generato dalla sovrapposizione degli spettri di numerose molecole differenti, è caratterizzato da bande di assorbimento, piuttosto che singole linee, chiamate bande rotazionali, vibrazionali o roto-vibrazionali. Grazie a questa complessità, un singolo spettro può dare informazioni relative a varie altitudini e proprietà. Un progetto di Maestri et al. (2019) mostra come sia possibile classificare con una routine automatica i casi di cielo sereno e nuvoloso, attraverso un algoritmo di machine learning basato sul confronto tra spettri infrarossi. I risultati migliori sono ottenuti utilizzando una combinazione di numeri d’onda nel FIR e nel MIR, evidenziando così l’utilità della componente FIR nell’intero processo. La percentuale delle classificazioni corrette è del 98%, un miglioramento notevole rispetto a progetti precedenti dello stesso tipo. Una migliore identificazione e classificazione delle condizioni del cielo consente inoltre di ricavare numerosi parametri geofisici in maniera più accurata.

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Hofert, Glenn D. "Spectral analysis of vortex/free-surface interaction." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283210.

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Behrens, Richard J. "Change detection analysis with spectral thermal imagery." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA356044.

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Thesis (M.S. in Space Systems Operations) Naval Postgraduate School, September 1998.
"September 1998." Thesis advisor(s): Richard Christopher Olsen, David D. Cleary. Includes bibliographical references (p. 129-131). Also available online.

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42

Raksuntorn, Nareenart. "Unsupervised spectral mixture analysis for hyperspectral imagery." Diss., Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-04192009-142516.

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43

Greger, Klaus. "OligoChannel spectral analysis in stereotactic laser neurosurgery." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=967776384.

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44

Folatelli, Gastón. "Type Ia Supernova Cosmology : Quantitative Spectral Analysis." Doctoral thesis, Stockholm University, Department of Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-80.

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Type Ia supernovae have been successfully used as standardized candles to study the expansion history of the Universe. In the past few years, these studies led to the exciting result of an accelerated expansion caused by the repelling action of some sort of dark energy. This result has been confirmed by measurements of cosmic microwave background radiation, the large-scale structure, and the dynamics of galaxy clusters. The combination of all these experiments points to a “concordance model” of the Universe with flat large-scale geometry and a dominant component of dark energy.

However, there are several points related to supernova measurements which need careful analysis in order to doubtlessly establish the validity of the concordance model. As the amount and quality of data increases, the need of controlling possible systematic effects which may bias the results becomes crucial. Also important is the improvement of our knowledge of the physics of supernovae events to assure and possibly refine their calibration as standardized candle.

This thesis addresses some of those issues through the quantitative analysis of supernova spectra. The stress is put on a careful treatment of the data and on the definition of spectral measurement methods. The comparison of measurements for a large set of spectra from nearby supernovae is used to study the homogeneity and to search for spectral parameters which may further refine the calibration of the standardized candle. One such parameter is found to reduce the dispersion in the distance estimation of a sample of supernovae to below 6%, a precision which is comparable with the current lightcurve-based calibration, and is obtained in an independent manner. Finally, the comparison of spectral measurements from nearby and distant objects is used to test the possibility of evolution with cosmic time of the intrinsic brightness of type Ia supernovae.

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Dahlgren, Hanna. "Multi-spectral analysis of fine scale aurora." Doctoral thesis, KTH, Rymd- och plasmafysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-24907.

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The Aurora Borealis is the visible manifestation of the complex plasma interaction between the solar wind and the Earth's magnetosphere and ionosphere. Ground based and in situ measurements demonstrate a prevalence of dynamic fine structure within auroral displays, with spatial scales down to tens of metres and time variations occurring on a fraction of a second.The fine-scale morphology is related to structuring of auroral currents and electric fields and detailed spatial, spectral and temporal observations of the aurora are crucial in understanding the electrodynamic processes taking place in the ionosphere and in its coupling to the magnetosphere. In this thesis, the low-light optical instrument ASK (Auroral Structure and Kinetics) is used to image small-scale structures in the aurora at very high spatial and temporal resolution. ASK is a multi-spectral instrument, imaging the aurora in three selected emissions simultaneously. This provides information on the energy of the precipitating electrons. The SIF (Spectrographic Imaging Facility) instrument has been used in conjunction with ASK, to give a more complete picture of the spectral characteristics of the aurora, and to determine the degree of contaminating emissions present in the same spectral interval as the emission lines observed by ASK. Data from ASK and SIF are used to study the relation between the morphology and dynamics of small-scale structures in the aurora and the energy of the precipitating electrons. By comparing electron density profiles provided by EISCAT (European Incoherent SCATter) radar measurements with modeling results, information on the characteristic energy and the energy flux of the precipitating electrons can be obtained. One of the ASK channels is imaging a metastable O+ emission, which has a lifetime of about 5 s. By tracing the afterglow in this channel optically a direct measure of the E x B drift is obtained from which the local ionospheric electric field can be calculated. ASK data has also been used to analyse the properties of a distorted auroral arc, in which auroral structuring was found to take place simultaneously at different spatial scales. The smallest features, 'ruffs', are undulations found to develop on the edge of an auroral curl, fold or shear. Detailed optical studies of black aurora, including both the type which is associated with plasma shear motions and no or weak shear motions were conducted from ASK data, to investigate the spectral properties and fine scale morphology of the black structures and to shed light on the processes behind this phenomenon.
QC 20101001

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46

Folatelli, Gastón. "Type Ia supernova cosmology : quantitative spectral analysis /." Stockholm : Fysikum, Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-80.

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47

Di, Gesù Giacomo. "Semiclassical spectral analysis of discrete Witten Laplacians." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2013/6528/.

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A discrete analogue of the Witten Laplacian on the n-dimensional integer lattice is considered. After rescaling of the operator and the lattice size we analyze the tunnel effect between different wells, providing sharp asymptotics of the low-lying spectrum. Our proof, inspired by work of B. Helffer, M. Klein and F. Nier in continuous setting, is based on the construction of a discrete Witten complex and a semiclassical analysis of the corresponding discrete Witten Laplacian on 1-forms. The result can be reformulated in terms of metastable Markov processes on the lattice.
In dieser Arbeit wird auf dem n-dimensionalen Gitter der ganzen Zahlen ein Analogon des Witten-Laplace-Operatoren eingeführt. Nach geeigneter Skalierung des Gitters und des Operatoren analysieren wir den Tunneleffekt zwischen verschiedenen Potentialtöpfen und erhalten vollständige Aymptotiken für das tiefliegende Spektrum. Der Beweis (nach Methoden, die von B. Helffer, M. Klein und F. Nier im Falle des kontinuierlichen Witten-Laplace-Operatoren entwickelt wurden) basiert auf der Konstruktion eines diskreten Witten-Komplexes und der Analyse des zugehörigen Witten-Laplace-Operatoren auf 1-Formen. Das Resultat kann im Kontext von metastabilen Markov Prozessen auf dem Gitter reformuliert werden und ermöglicht scharfe Aussagen über metastabile Austrittszeiten.

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48

Jean, Yves Darly. "Accelerated volume rendering via spatial/spectral analysis." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/12891.

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49

Al-Wasel, Ibrahim A. "Spectral analysis for replicated biomedical time series." Thesis, Lancaster University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412585.

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Watkins, Joe. "Spectral analysis of a 1D Schrödinger problem." Thesis, University of Kent, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633694.

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Dissertations / Theses on the topic 'Spectral analysis'

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