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1
Dahl, Jason F. "Time Aliasing Methods of Spectrum Estimation". Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd157.pdf.
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鄧愛紅 e Aihong Deng. "Some studies towards improving positron lifetime spectroscopy for semiconductors". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31214083.
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Bing, Zhou. "Crosshole resistivity and acoustic velocity imaging : S.5-D helmholtz equation modeling and inversion /". Title page, contents and abstract only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phb613.pdf.
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Chan, Chun-yu. "Mass spectrometric analysis of selected glycoproteins". Thesis, Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B3147942X.
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Tadros-Attalla, Helen. "Power spectrum analysis of redshift surveys". Thesis, University of Oxford, 1996. https://ora.ox.ac.uk/objects/uuid:5a5786db-748e-4c78-bab8-c89a4eda2f07.
Testo completoAbstract (sommario):
This thesis describes a study of the clustering properties of galaxies and clusters of galaxies as measured by the power spectrum (P(k)) and the counts in cells statistic. The samples used are the optical Stromlo-APM galaxy survey, the APM cluster survey and the IRAS 1.2Jy, QDOT and PSCz surveys. Throughout, N-body simulations, for a variety of cosmological models, are used to test methods and to supplement analytic error estimates. For the Stromlo-APM sample the amplitude of the power spectrum is dependent on galaxy morphology. Early-type galaxies show a higher clustering amplitude than late-type galaxies by a factor of ~ 1.8. There is also tentative evidence for some dependence of the clustering amplitude on galaxy luminosity. The parameter Ω0.6/b is estimated via a comparison with the real-space power spectrum of the two-dimensional APM galaxy survey. For APM clusters the power spectrum is measured to very small wave numbers, with a possible detection of the expected turn-over. The results are inconsistent with the standard cold dark matter model. The shape of P( k) for clusters is approximately the same as that for Stromlo-APM galaxies but amplified by a factor of ~ 3.5. The power spectrum of the QDOT sample depends sensitively on the galaxy weighting scheme, probably due the manner in which the region of the Hercules supercluster is sampled. A best estimate of the power spectrum of IRAS galaxies is computed by combining the IRAS l.2Jy and QDOT samples. The PSCz galaxy power spectrum is also computed. The PSCz galaxies have a clustering amplitude twice that of optical galaxies. A similar result is found from a joint counts in cells analysis. Redshift-space distortions in the PSCz sample are analysed using a spherical harmonic decomposition of the density field. The value of Ω0.6/b = 1 is ruled out by this analysis at the 2σ significance level.
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Mendes, Luís Miguel Vinhas. "Measurements and analysis of spectrum activity". Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/7725.
Testo completoAbstract (sommario):
Mestrado em Engenharia Electrónica e TelecomunicaçõesThe dissertation deals with measuring and analyzing spectrum occupancy of a GSM900 band, DCS1800 band and all UMTS bandwidth. A modelization for analog power and binary quantized power is given. In the case of analog power, histograms of the power distribution during one working day are presented. In the case of quantized power the two time statistics, the time period of opportunities distribution and the time between opportunities distribution are presented, described and modeled. The measurement setup is standing in line of sight with the base station. Also, in terms of maximum sensitivity the measurement setup is described and analyzed. Spectrum non occupancy in terms of total time for the GSM900 band and the DCS1800 band is given, for a working day.
Nesta dissertação são feitas medidas e a análise de ocupação de espectro em uma banda de GSM900, uma banda de DCS1800 e toda a largura de banda do UMTS. É apresentada uma modelização para potência analógica e para a potência binária quantizada. No caso da potência analógica são apresentados histogramas da distribuição de potência ao longo de um dia útil. No caso da potência quantizada as duas estatísticas, distribuição do período de tempo de oportunidades e distribuição do tempo entre oportunidades, são apresentadas, descritas e modeladas. O setup de medida encontra-se em linha de vista com a estação base. O setup é descrito e analisado em termos de máxima sensibilidade. A desocupação de espectro em termos de tempo total para a banda de GSM900 e para a banda DCS1800 é fornecida, para um dia de útil.
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Clayton, Michael J. "Analysis of the ultraviolet emissions of nitric oxide from mid-latitude rocket observations". Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA237340.
Testo completoAbstract (sommario):
Thesis (M.S. in Physics)--Naval Postgraduate School, June 1990.Thesis Advisor(s): Cleary, David D. "June 1990." Description based on signature page. as viewed on October 19, 2009. DTIC Identifiers: Dayglow, emission spectra, ultraviolet spectra, theses. Author(s) subject terms: Ultraviolet spectra, dayglow, nitric oxide. Includes bibliographical references (p. 57-58). Also available in print.
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Strachan, Clare, e n/a. "Spectroscopic investigation and quantitation of polymorphism and crystallinity of pharmaceutical compounds". University of Otago. School of Pharmacy, 2005. http://adt.otago.ac.nz./public/adt-NZDU20070427.141108.
Testo completoAbstract (sommario):
Spectroscopy is increasingly used to investigate and monitor the solid state forms of pharmaceutical materials and products. Spectroscopy�s speed, nondestructive sampling, compatibility with fibre optics and safety also make it attractive for in-line monitoring.
In this thesis, the spectroscopic techniques Fourier transform Raman spectroscopy, terahertz pulsed spectroscopy and second harmonic generation were used to characterise and quantify polymorphism and crystallinity of pharmaceutical compounds. Where possible, the multivariate analysis technique partial least squares was used for quantitative analysis. Fourier transform Raman spectroscopy detects polarisability changes mainly associated with molecular vibrations. Terahertz pulsed spectroscopy is a new spectroscopic technique that operates between the infrared and microwave regions of the electromagnetic spectrum and detects dipole moment changes mainly associated with crystalline phonon vibrations in the solid state. Second harmonic generation is a nonlinear optical phenomenon that depends on the dipole moment in crystals and crystal symmetry.
Several materials capable of existing in different solid state forms were used. FT-Raman spectroscopy was able to differentiate carbamazepine forms I and III, enalapril maleate forms I and II and γ-crystalline and amorphous indomethacin. Combined with partial least squares the technique could quantify binary mixtures of CBZ forms I and III with a limit of detection as low as 1%, and mixtures of enalapril maleate with a limit of detection of as low as 2%.
Terahertz pulsed spectroscopy obtained very different spectra for carbamazepine forms I and III, enalapril maleate forms I and II, γ-crystalline and amorphous indomethacin, crystalline and supercooled thermotropic liquid crystalline fenoprofen calcium, three forms of lactose, and five forms of sulphathiazole. At present the modes in the spectra cannot be attributed to specific phonon modes. Quantitation of binary mixtures of different forms of a compound using partial least squares analysis usually resulted in a limit of detection of about 1%.
Second harmonic generation was used to quantify binary mixtures of different forms of enalapril maleate and lactose, as well as binary mixtures of enalapril maleate form II and polyvinylpyrrolidone. A quantitative relationship was present for each of the mixtures, however the limits of detection were usually above 10%. The high value is probably due to the machine being a prototype and univariate analysis associated with a single output variable. Future improvements to the apparatus and measurement parameters are likely to reduce the limits of detection. Ranitidine hydrochloride polymorphs could also be differentiated using second harmonic generation, however γ-crystalline and amorphous indomethacin and forms I and III of carbamazepine could not.
The methods used in this thesis were successfully used for qualitative and quantitative analysis of polymorphism and crystallinity of pharmaceutical compounds. TPS and SHG are useful additions to the range of experimental techniques that can be used to investigate and monitor properties of pharmaceutical solids.
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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.
Testo completoAbstract (sommario):
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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Daigle, J. A. Bernard. "Development of an ion trap mass spectrometer for elemental analysis". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30688.
Testo completoAbstract (sommario):
Mass spectrometry is a widely used technique for the performance of elemental analysis: not only does it provides excellent limits of detection for a large number of elements, but it is also able to provide information about the isotopic distribution of the analyte. The radio-frequency quadrupole ion trap is a relatively new design of mass spectrometer, which offers the ability to confine charged particles for extended periods of time in a well defined volume by applying a radio-frequency oscillating voltage to an arrangement of three electrodes. A mass analysis of the trapped ions can be obtained by selectively extracting the ions from the cavity of the trap, where they can be detected by an electron multiplier. Despite its unique capabilities, to date the applications of the ion trap mass spectrometer have mostly been restricted to gas chromatography detection. Until recently, there have been very few attempts to use it for any other types of routine analysis.
Our interest lies in the development of an instrument capable of performing a complete mass spectrometric elemental analysis of small volume liquid samples (a few (μL) at trace or ultra-trace concentration levels. The ability of the ion trap to accumulate ions in its cavity and to provide an entire mass spectrum of these ions in a single scan of the radio-frequency oscillating voltage applied between the electrodes, makes it a very interesting candidate for the ultra-trace analysis of small size samples. However, to perform an analysis on a sample with the ion trap the sample must first be vaporized; and if an elemental analysis is required, the sample will also have to be atomized. The graphite furnace atomizer used in atomic absorption spectroscopy offers a number of advantages which make it potentially useful for this purpose: it has a high transport efficiency of the analyte from liquid or solid state to the vapour phase, the ionization of the analyte in the furnace is very low (as required by the ion trap) and it handles small volume samples very well. A graphite furnace ion
trap mass spectrometer was designed to fulfil the need of having instrumentation capable of multielemental mass spectrometric analysis of small volume samples containing traces of the analytes of interest.
This document contains a description of the principles of operation of the ion trap as well as a detailed description of the instrument actually built. Data are presented in order to assess the capabilities of the instrument, as well as some of the problems encountered with it. The results obtained with the graphite furnace ion trap mass spectrometer allow us to conclude that the proposed design is not appropriate for the performance of elemental analysis, but is appropriate for mass spectrometric study of low boiling point compounds which can interfere with atomic absorption analysis: it is calculated that these compounds could be analysed at the ppm level.
Promising results obtained with a set up in which the analyte is vaporized directly into the cavity of the ion trap through laser ablation are also presented. These limited results show the potential of this methodology for direct elemental analysis of solid samples.Science, Faculty of
Chemistry, Department of
Graduate
11
Bell, Angela. "Analysis of the barley grain protease spectrum". Thesis, Heriot-Watt University, 2012. http://hdl.handle.net/10399/2585.
Testo completoAbstract (sommario):
Malting is the controlled germination of barley grains, under specific conditions and up to the point of grain modification, and is the keystone of the brewing and distilling industries. Protease enzyme activity is an important constituent of this process as not only does this catalyse the degradation of the grains protein stores, but it also has involvement in other aspects of the germination process such as the activation of β – amylase. However, despite their importance, little is known of the identities and specific roles of the protease classes in the malting and germination process. With this in mind a biochemical and proteomic approach was taken in order to attempt to identify protease enzymes from malted and germinating barley grains and also to identify the roles of specific protease classes in barley grain malting and germination. FPLC based protein fractionation, SDS – PAGE analysis and MALDI – ToF mass spectroscopy were used in an attempt to purify metallo and serine class proteases from extracts of four day micro malted malt and germinating barley grains. A combination of class specific protease inhibitors, germination studies, enzyme assays of both barley grain proteases and specific starch degrading enzymes, and western blotting were employed to investigate the roles of the different protease classes in both overall grain physiology during germination and specifically, in the regulation of enzymes involved in starch breakdown. These investigations show that the serine and aspartate class proteases have a role in the positive regulation of the amounts of α – amylase present in barley grains during germination in a process that may involve gibberellic acid signalling. Furthermore, it was also shown that the serine class proteases have a role in the negative regulation of β – amylase activity during germination, thus revealing the complexity of the regulatory roles of barley grain proteases during grain germination. In addition, germination studies carried out in the presence of both the divalent cation chelator 1, 10 phenanthroline and different divalent cations revealed the potential importance of transition metal ions such as zinc, iron and manganese in the onset of grain germination.
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Krishnannair, Syamala. "Multiscale process monitoring with singular spectrum analysis". Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5246.
Testo completoAbstract (sommario):
Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2010.Thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Engineering (Extractive Metallurgy) In the Department of Process Engineering at the University of Stellenbosch
ENGLISH ABSTRACT: Multivariate statistical process control (MSPC) approaches are now widely used for performance monitoring, fault detection and diagnosis in chemical processes. Conventional MSPC approaches are based on latent variable projection methods such as principal component analysis and partial least squares. These methods are suitable for handling linearly correlated data sets, with minimal autocorrelation in the variables. Industrial plant data invariably violate these conditions, and several extensions to conventional MSPC methodologies have been proposed to account for these limitations. In practical situations process data usually contain contributions at multiple scales because of different events occurring at different localizations in time and frequency. To account for such multiscale nature, monitoring techniques that decompose observed data at different scales are necessary. Hence the use of standard MSPC methodologies may lead to unreliable results due to false alarms and significant loss of information. In this thesis a multiscale methodology based on the use of singular spectrum analysis is proposed. Singular spectrum analysis (SSA) is a linear method that extracts information from the short and noisy time series by decomposing the data into deterministic and stochastic components without prior knowledge of the dynamics affecting the time series. These components can be classified as independent additive time series of slowly varying trend, periodic series and aperiodic noise. SSA does this decomposition by projecting the original time series onto a data-adaptive vector basis obtained from the series itself based on principal component analysis (PCA). The proposed method in this study treats each process variable as time series and the autocorrelation between the variables are explicitly accounted for. The data-adaptive nature of SSA makes the proposed method more flexible than other spectral techniques using fixed basis functions. Application of the proposed technique is demonstrated using simulated, industrial data and the Tennessee Eastman Challenge process. Also, a comparative analysis is given using the simulated and Tennessee Eastman process. It is found that in most cases the proposed method is superior in detecting process changes and faults of different magnitude accurately compared to classical statistical process control (SPC) based on latent variable methods as well as the wavelet-based multiscale SPC.
AFRIKAANSE OPSOMMING: Meerveranderlike statistiese prosesbeheerbenaderings (MSPB) word tans wydverspreid benut vir werkverrigtingkontrolering, foutopsporing en .diagnose in chemiese prosesse. Gebruiklike MSPB word op latente veranderlike projeksiemetodes soos hoofkomponentontleding en parsiele kleinste-kwadrate gebaseer. Hierdie metodes is geskik om lineer gekorreleerde datastelle, met minimale outokorrelasie, te hanteer. Nywerheidsaanlegdata oortree altyd hierdie voorwaardes, en verskeie MSPB is voorgestel om verantwoording te doen vir hierdie beperkings. Prosesdata afkomstig van praktiese toestande bevat gewoonlik bydraes by veelvuldige skale, as gevolg van verskillende gebeurtenisse wat by verskillende lokaliserings in tyd en frekwensie voorkom. Kontroleringsmetodes wat waargenome data ontbind by verskillende skale is nodig om verantwoording te doen vir sodanige multiskaalgedrag. Derhalwe kan die gebruik van standaard-MSPB weens vals alarms en beduidende verlies van inligting tot onbetroubare resultate lei. In hierdie tesis word . multiskaalmetodologie gebaseer op die gebruik van singuliere spektrumontleding (SSO) voorgestel. SSO is . lineere metode wat inligting uit die kort en ruiserige tydreeks ontrek deur die data in deterministiese en stochastiese komponente te ontbind, sonder enige voorkennis van die dinamika wat die tydreeks affekteer. Hierdie komponente kan as onafhanklike, additiewe tydreekse geklassifiseer word: stadigveranderende tendense, periodiese reekse en aperiodiese geruis. SSO vermag hierdie ontbinding deur die oorspronklike tydreeks na . data-aanpassende vektorbasis te projekteer, waar hierdie vektorbasis verkry is vanaf die tydreeks self, gebaseer op hoofkomponentontleding. Die voorgestelde metode in hierdie studie hanteer elke prosesveranderlike as . tydreeks, en die outokorrelasie tussen veranderlikes word eksplisiet in berekening gebring. Aangesien die SSO metode aanpas tot data, is die voorgestelde metode meer buigsaam as ander spektraalmetodes wat gebruik maak van vaste basisfunksies. Toepassing van die voorgestelde tegniek word getoon met gesimuleerde prosesdata en die Tennessee Eastman-proses. . Vergelykende ontleding word ook gedoen met die gesimuleerde prosesdata en die Tennessee Eastman-proses. In die meeste gevalle is dit gevind dat die voorgestelde metode beter vaar om prosesveranderings en .foute met verskillende groottes op te spoor, in vergeleke met klassieke statistiese prosesbeheer (SP) gebaseer op latente veranderlikes, asook golfie-gebaseerde multiskaal SP.
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Matsuoka, Danilo Hiroshi. "Forecasting brazilian inflation with singular spectrum analysis". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/147410.
Testo completoAbstract (sommario):
O objetivo deste artigo é avaliar previsões da inflação brasileira a partir do método não-paramétrico de Análise Espectral Singular (SSA). O exercício de previsão utiliza o esquema de janelas rolantes. Diferentes estratégias de combinação de previsões e procedimentos de seleção de variáveis para métodos multivariados foram contempladas. Para robustez, cinco horizontes de previsão foram utilizados. A avaliação das previsões considera diversos procedimentos e medidas estatísticas para oferecer conclusões confiáveis, incluindo razões de erro quadrático médio de previsão, teste de igualdade condicional de habilidade preditiva, diferenças de erro quadrático médio de previsão cumulativas e Model Confidence Set. Os resultados mostram que o SSA supera consistentemente os métodos competidores. Quase todas as previsões SSA superam os competidores em termos de erro quadrático médio de previsão, e em vários casos, com significância estatística. A análise da porção fora da amostra indica superioridade em performance relativa do SSA, especialmente no período de choque nos preços de energia elétrica. Adicionalmente, métodos SSA sempre foram incluídos no conjunto superior do Model Confidence Set. A falta de estudos relacionados com previsão da inflação brasileira e a relativa escassez de análises de previsões via métodos não-paramétricos ressaltam a relevância deste artigo. Não existem pesquisas na literatura de previsão de inflação brasileira aplicando SSA. Uma das estratégias de combinação de previsões aplicadas neste artigo não é comumente encontrada na literatura, na medida em que envolve combinações de diferentes especificações para cada método de previsão. Adicionalmente, restrições de parâmetros foram impostas nas previsões SSA, uma prática não reportada na literatura.The purpose of this paper is to evaluate Brazilian inflation forecasts produced by the nonparametric method Singular Spectrum Analysis (SSA). This forecasting exercise employs rolling windows scheme. Different strategies of forecast combinations and variable selection procedures for multivariate methods were contemplated. For robustness, five forecast horizons were used. The forecast evaluation considers several statistical measures and procedures to offer reliable conclusions, including mean squared forecast error ratios, tests of equal conditional predictive ability, cumulative square forecast error difference and Model Confidence Set. The results show that SSA consistently outperforms the competitive methods. Almost all SSA forecasts outperforms the competitors in the mean squared forecast error sense, and several with statistical significance. Analysis of the out-of-sample portion indicates relative superior performance of SSA, especially over the period of electricity shock of prices. SSA methods were always included in the superior set of Model Confidence Set procedures. The lack of studies related to Brazilian inflation forecasting and the relative scarcity of nonparametric methods of forecasting analysis highlights the relevance of this paper. There is no research in Brazilian inflation literature applying SSA. One of the forecast combination strategies applied in this paper is not commonly found in the literature, as it involves combinations of different specifications for each forecast method. Additionally, parameter restrictions on SSA forecasts were imposed, a practice which is not reported in the literature.
14
Sharkasi, Youssif F. "Cooperative spectrum sensing : performance analysis and algorithms". Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/8369/.
Testo completoAbstract (sommario):
The employment of cognitive (intelligent) radios presents an opportunity to efficiently use the scarce spectrum with the condition that it causes a minimal disturbance to the primary user. So the cognitive or secondary users use spectrum sensing to detect the presence of primary user. In this thesis, different aspects related to spectrum sensing and cognitive radio performance are theoretically studied for the discussion and in most cases, closedform expressions are derived. Simulations results are also provided to verify the derivations. Firstly, robust spectrum sensing techniques are proposed considering some realistic conditions, such as carrier frequency offset (CFO) and phase noise (PN). These techniques are called the block-coherent detector (N2 -BLCD), the secondorder matched filter-I (SOMF-I) and the second-order matched filter-II (SOMF-II). The effect of CFO on N2 -BLCD and SOMF-I is evaluated theoretically and by simulation for SOMF-II. However, the effect of PN is only evaluated by simulation for all proposed techniques. Secondly, the detection performance of an energy detector (ED) is analytically investigated over a Nakagami-m frequency-selective (NFS) channel. Thirdly, the energy efficiency aspect of cooperative spectrum sensing is addressed, whereby the energy expenditure is reduced when secondary users report their test statistics to the fusion center (FC). To alleviate the energy consumption overhead, a censored selection combining based power censoring (CSCPC) is proposed. The accomplishment of energy saving is conducted by not sending the test statistic that does not contain robust information or it requires a lot of transmit power. The detection performance of the CSCPC is analytically derived using stochastic geometry tools and verified by simulation. Simulation results show that that the CSCPC technique can reduce the energy consumption compared with the conventional techniques while a detection performance distortion remains negligible. Finally, an analytical evaluation for the cognitive radio performance is presented while taking into consideration realistic issues, such as noise uncertainty (NU) and NFS channel. In the evaluation, sensing-throughput tradeoff is used as an examination metric. The results illustrate the NU badly affects the performance, but the performance may improve when the number of multipath increases.
15
Deng, Cheng. "Time Series Decomposition Using Singular Spectrum Analysis". Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etd/2352.
Testo completoAbstract (sommario):
Singular Spectrum Analysis (SSA) is a method for decomposing and forecasting time series that recently has had major developments but it is not yet routinely included in introductory time series courses. An international conference on the topic was held in Beijing in 2012. The basic SSA method decomposes a time series into trend, seasonal component and noise. However there are other more advanced extensions and applications of the method such as change-point detection or the treatment of multivariate time series. The purpose of this work is to understand the basic SSA method through its application to the monthly average sea temperature in a point of the coast of South America, near where “EI Ni˜no” phenomenon originates, and to artificial time series simulated using harmonic functions. The output of the basic SSA method is then compared with that of other decomposition methods such as classic seasonal decomposition, X-11 decomposition using moving averages and seasonal decomposition by Loess (STL) that are included in some time series courses.
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Mulye, Apoorva. "Power Spectrum Density Estimation Methods for Michelson Interferometer Wavemeters". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35500.
Testo completoAbstract (sommario):
In Michelson interferometry, many algorithms are used to detect the number of active laser sources at any given time. Conventional FFT-based non-parametric methods are widely used for this purpose. However, non-parametric methods are not the only possible option to distinguish the peaks in a spectrum, as these methods are not the most suitable methods for short data records and for closely spaced wavelengths. This thesis aims to provide solutions to these problems. It puts forward the use of parametric methods such as autoregressive methods and harmonic methods, and proposes two new algorithms to detect the closely spaced peaks for different scenarios of optical signals in wavemeters. Various parametric algorithms are studied, and their performances are compared with non-parametric algorithms for different criteria, e.g. absolute levels, frequency resolution, and accuracy of peak positions. Simulations are performed on synthetic signals produced from specifications provided by our sponsor, i.e., a wavemeter manufacturing company.
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Dorcey, Charles T. "FFT-based spectrum analysis using a Digital Signal Processor". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA401369.
Testo completoAbstract (sommario):
Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, December 2001."December 2001." Thesis Advisor(s): Loomis, Herschel H. Includes bibliographical references (p. 55). Also available online.
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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.
Testo completoAbstract (sommario):
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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Walsh, Penelope Jane, e n/a. "Modelling and spectroscopy of polypyridyl and porphyrin complexes for electroluminescence and solar cell applications". University of Otago. Department of Chemistry, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070927.151236.
Testo completoAbstract (sommario):
This thesis reports the spectroscopic and computational studies of two classes of compounds, which have applications in new optoelectronic materials technology. Substituted ligands of dipyrido-[3,2a:2�,3�c]phenazine (dppz), and their Cu(I), Re(I) and Ru(II) complexes have utility in organic electroluminescent devices. A series of Zn(II) tetraphenylporphyrins with conjugated functional groups at the β-position have been used with success in liquid heterojunction dye-sensitized solar cells. The vibrational spectra and optoelectronic properties of the two classes were investigated using Raman, resonance Raman and transient resonance Raman spectroscopy, in conjunction with density functional theory methods.
Density functional theory frequency calculations were used to aid vibrational mode assignments for the dppz compounds, and show close agreement with the experimental non-resonance Raman spectra. The enhancement of modes which are localized on differing sections of the ligand was identified. The nature of the absorbing chromophores for the dppz ligands and complexes was established using resonance Raman spectroscopy in concert with vibrational assignments from calculations. Transient resonance Raman spectra of the ligands provided spectral signatures for the triplet ligand-centred state; these features were observed in the TR� spectra of the metal complexes, along with other features attributable to MLCT states.
Electroluminescent devices were fabricated using the dppz ligands and complexes as emissive dopants, and their properties investigated. The optoelectronic behaviour of the devices was found to be influenced by the mechanism of exciton formation on the dopant. The device properties were also dependent on the dopant concentration, the concentrations of other components and the driving voltage.
The electronic structure of the porphyrin compounds was investigated using time-dependent density functional theory methods. Comparison of calculated optical transitions with experimental data shows that the calculations predict trends in the optical absorption spectra with change of functional group and with increase in conjugation chain length. The calculations suggest that the electron-withdrawing substituent decreases the configuration interaction effect by breaking the degeneracy of the two lowest unoccupied MOs, and other configuration interaction effects come into play involving other frontier MOs. Interrupting the conjugation of the functional group is shown to mitigate the breakdown of the configuration interaction.
The perturbation of the normal electronic structure of the porphyrin by the substituent was also investigated using resonance Raman spectroscopy. Vibrational analysis identified bands due to the substituent, implying coupling between the porphyrin and substituent chromophores. Changes in frequency of porphyrin core modes due to the differing substituents and different metal centres were reproduced by density functional theory calculations.
This project has allowed the spectroscopic investigation of the active optical states in a number of polypyridyl and porphyrin compounds, and determined the efficacy of DFT and TDDFT calculations to predict the properties of these compounds.
20
Reiss, Boris. "Development of a two-tone frequency modulation tunable diode laser absorption spectrometer (TTFM-TDLAS) for measuring methane fluxes". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0016/MQ56199.pdf.
Testo completo
21
Medina, Gerardo Juan. "Ligand isotope vibrational spectroscopic and DFT studies of Pt(II) and Cu(I) complexes". Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1004982.
Testo completoAbstract (sommario):
Ligand-isotope labelling studies were performed on Zeise’s salt derivatives with pyridine N-oxide and quinoline N-oxide, their perdeuterated and O-18 isotopomers, C₂D₄ and ¹³CO, and the results of the vibrational analyses are reported. The isotopomers are modelled utilizing DFT calculations at the B3LYP level with the 6-31 G** basis set, and a pseudopotential level for the Pt atom. The calculated and observed structure and vibrational spectra correlate well. The crystal structures of [Pt(C₂2H₄)(pyO)Cl₂] and [Pt(CO)(quinO)Br₂] are reported. The frequency for the νPt-O vibration, ambiguously assigned in the literature, is here assigned unequivocally at 400 cm⁻¹. Previously observed, but inadequately described phenomena are addressed: the νN-O vibration in substituted quinoline N-oxides has been assigned previously at significantly different frequencies, depending on the nature of the substituent. This suggests that there is no specific mid-ir band associated with a high N-O character. A suitable explanation is presented for this phenomenon, showing that in low symmetry systems (eg. quinO) the N-O stretch is dispersed among several modes, whereas in high symmetry systems (eg. pyO) only a few limited modes have a high N-O character. A theoretical study of Cu(I) carbonyl compounds with macrocyclic ligands is presented. Local and global HSAB parameters applied to the donor and Cu atoms are used to explain the observed reactivities and the available spectroscopic data. Extended to [Cu(CO){H₂N(CH₂)[subscript n]NH(CH₂)[subscript m] NH₂}] BPh₄ (where n = 2, m = 2, 3 and n =3, m = 3, 4) and their -d₅ and ¹³CO isotopomers, subtle differences obtained experimentally for the CO stretching frequency in this series have been reproduced in the DFT calculations at the B3LYP level, using the 6-31 G* and 6-31 G** basis sets. Several properties (ligand pK[subscript a] values, νCO frequencies, etc.) correlate with some HSAB descriptors. Vibrational analyses are presented of Cu(I) carbonyl Schiff-base derivatives of N-Benzylidene-N’-[2-(benzyilidene-amino)-ethyl]-ethane-1,2-diamine, {2,2N3(C₆H₄R)₂}, and their -d₅ and ¹³CO isotopomers. The crystal structure of [Cu(CO){2,2N3(C₆H₅)₂}]BPh₄ is reported. From geometry optimizations and the HSAB descriptors, spectroscopic trends ([n]Cu-N and [nu]CO) are related to calculated global hardness and the Hammett substituent parameters, and are discussed in terms of σ-donation and π-backbonding of Cu- CO.
22
Ovenden, Simon P. B. "Preparation of a natural product extract library for investigation against disease states specific to defence health a mini long range research project /". Fishermans Bend Victoria : Defence Science and Technology Organisation, 2009. http://hdl.handle.net/1947/9861.
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23
Luo, Yong. "A spread spectrum ranging system, analysis and simulation". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq30512.pdf.
Testo completo
24
Colice, Christopher Max. "Transformations in optics for radio-frequency spectrum analysis". Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3256393.
Testo completo
25
Wilson, Catherine. "Further analysis of the electronic spectrum of FeH". Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365782.
Testo completo
26
Cardenas, Juarez Marco Aurelio. "Spectrum sensing and throughput analysis for cognitive radio". Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582744.
Testo completoAbstract (sommario):
Cognitive radio (CR) technology offers an innovative solution to improve spectrum efficiency, thus satisfying the greater demand to be placed on the electromagnetic spectrum by future wireless networks and communications. In this sense, the ulti- mate purpose of the spectrum sensing feature in cognitive radio is to determine the absence or presence of licensed users' signals in a frequency band of interest. More- over, due to the wide variety of scenarios in which cognitive radios may operate and the random nature of wireless channels, spectrum sensing algorithms are expected to perform well at a very low signal-to-noise-ratio (SNR), thus playing not only an important but also a very challenging role in CR. In this thesis, locally optimum (LO) detection, (known to be optimum at low SNR), is adopted in the design of blind and semi-blind detection algorithms by fo- cusing on linear modulation in the presence of an unknown phase shift and additive white Gaussian noise. The proposed LO detectors are shown to significantly out- perform the energy detector in the case of BPSK signals and to be less sensitive to noise power mismatch whilst their complexity is only slightly higher than that of the energy detector. Furthermore, the spectrum sensing performance is improved by taking advantage of the spatial diversity gained through cooperation. In addition, next generation wireless networks will need higher data rates to meet the requirements of the expected customers and services. The spectrum sen- sing duration and the secondary user's achievable throughput trade-off problem is addressed here by allowing the constraint on the probability of detection to be in outage with a specified percentage, taking into account the detrimental effect of unknown channel gains over different fading conditions in centralised cooperative networks, which is a more realistic scenario. The spectrum sensing time/secondary user's achievable throughput trade-off is then formulated and optimised accordingly.
27
Barkhuizen, Marlize. "Analysis of process data with singular spectrum methods". Thesis, Stellenbosch : University of Stellenbosch, 2003. http://hdl.handle.net/10019.1/16252.
Testo completoAbstract (sommario):
Thesis (MScIng)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: The analysis of process data obtained from chemical and metallurgical engineering systems is a crucial aspect of the operating of any process, as information extracted from the data is used for control purposes, decision making and forecasting. Singular spectrum analysis (SSA) is a relatively new technique that can be used to decompose time series into their constituent components, after which a variety of further analyses can be applied to the data. The objectives of this study were to investigate the abilities of SSA regarding the filtering of data and the subsequent modelling of the filtered data, to explore the methods available to perform nonlinear SSA and finally to explore the possibilities of Monte Carlo SSA to characterize and identify process systems from observed time series data. Although the literature indicated the widespread application of SSA in other research fields, no previous application of singular spectrum analysis to time series obtained from chemical engineering processes could be found. SSA appeared to have a multitude of applications that could be of great benefit in the analysis of data from process systems. The first indication of this was in the filtering or noise-removal abilities of SSA. A number of case studies were filtered by various techniques related to SSA, after which a number of neural network modelling strategies were applied to the data. It was consistently found that the models built on data that have been prefiltered with SSA outperformed the other models. The effectiveness of localized SSA and auto-associative neural networks in performing nonlinear SSA were compared. Both techniques succeeded in extracting a number of nonlinear components from the data that could not be identified from linear SSA. However, it was found that localized SSA was a more reliable approach, as the auto-associative neural networks would not train for some of the data or extracted nonsensical components for other series. Lastly a number of time series were analysed using Monte Carlo SSA. It was found that, as is the case with all other characterization techniques, Monte Carlo SSA could not succeed in correctly classifying all the series investigated. For this reason several tests were used for the classification of the real process data. In the light of these findings, it was concluded that singular spectrum analysis could be a valuable tool in the analysis of chemical and metallurgical process data.
AFRIKAANSE OPSOMMING: Die analise van chemise en metallurgiese prosesdata wat verkry is vanaf chemiese of metallurgiese ingenieursstelsels is ‘n baie belangrike aspek in die bedryf van enige proses, aangesien die inligting wat van die data onttrek word vir prosesbeheer, besluitneming of die bou van prosesmodelle gebruik kan word. Singuliere spektrale analise is ‘n relatief nuwe tegniek wat gebruik kan word om tydreekse in hul onderliggende komponente te ontbind. Die doelwitte van hierdie studie was om ‘n omvattende literatuuroorsig oor die ontwikkeling van die tegniek en die toepassing daarvan te doen, beide in die ingenieursindustrie en in ander navorsingsvelde, die navors van die moontlikhede van SSA aangaande die verwydering van geraas uit die data en die gevolglike modellering van die skoon data te ondersoek, ‘n ondersoek te doen na sommige van die beskikbare tegnieke vir nie-lineêre SSA en laastens ‘n studie te maak van die potensiaal van Monte Carlo SSA vir die karakterisering en identifikasie van data verkry vanaf prosesstelsels. Ten spyte van aanduidings in die literatuur dat SSA wydverspreid toegepas word in ander navorsingsvelde, kon geen vorige toepassings gevind word van SSA op chemiese prosesse nie. Dit wil voorkom asof die chemiese nywerhede groot baat kan vind by SSA van prosesdata. Die eerste aanduiding van hierdie voordele was in die vermoë van SSA om geraas te verwyder uit tydreekse. ‘n Aantal tipiese gevalle is ondersoek deur van verskeie benaderings tot SSA gebruik te maak. Nadat die geraas uit die tydreekse van die toetsgevalle verwyder is, is neurale netwerke gebruik om die prosesse te modelleer. Daar is herhaaldelik gevind dat die modelle wat gebou is op data wat eers deur SSA skoongemaak is, beter presteer as die wat slegs op die onverwerkte data gepas is. Die effektiwiteit van lokale SSA en auto-assosiatiewe neurale netwerke om nie- lineêre SSA toe te pas is ook vergelyk. Albei tegnieke het daarin geslaag om nie- lineêre hoofkomponente van die data te onttrek wat nie geïdentifiseer kon word deur die lineêre benadering nie. Daar is egter gevind dat lokale SSA ‘n meer betroubare tegniek is, aangesien die autoassosiatiewe neurale netwerke nie op sommige van die datastelle wou leer nie en vir ander tydreekse sinnelose hoofkomponente onttrek het. Laastens is ‘n aantal tydreekse geanaliseer met behulp van Monte Carlo SSA. Soos met alle ander karakteriseringstegnieke, kon Monte Carlo SSA nie daarin slaag om al die tydreekse wat ondersoek is korrek te identifiseer nie. Om hierdie rede is ‘n kombinasie van toetse gebruik om die onbekende tydreekse te klassifiseer. In die lig van al hierdie bevindinge, is die gevolgtrekking gemaak dat singuliere spektrale analise ‘n waardevolle hulpmiddel kan wees in die analise van chemiese en metallurgiese prosesdata.
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Loureiro, Arthur Eduardo da Mota. "Galaxy Power Spectrum Analysis: A Monte-Carlo Approach". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-06072015-060434/.
Testo completoAbstract (sommario):
Many galaxy surveys are planned to release their data over the next few years. Each different survey has its own geometrical limitations, which reflects upon the data as a selection function the spatial distribution of certain types of galaxies. Given a galaxy map (real or mock), the main goal of this work is to obtain information about how the selection function affects some of the cosmological parameters which can be probed from large-scale structure. A Monte-Carlo Markov Chain method is proposed in order to probe the effects of considering the selection functions parameters as nuisance parameters. The method consists in combining realizations of simulated galaxy catalogs using theoretical matter power spectra, combined with an optimal power spectrum estimator method. Theory and data are then compared in a multivariate Gaussian representing the likelihood function. This Monte-Carlo method has proven robust and capable of probing selection function effects on the cosmological parameters, showing that the simple marginalization over the nuisance parameters might lead to wrong estimates on the cosmology. The method is applied to obtain forecasts for these effects on the upcoming J-PAS Luminous Red Galaxies data and is employed to obtain constraints on the Hubble parameter (H0), the dark matter density (c) and two parameters of the equation of state of dark energy (w0 and wa).Nos próximos anos, diversos levantamentos de galáxias planejam lançar uma quantidade considerável de novos dados, marcando, assim, o início da chamda era da cosmologia de precisão. Cada levantamento possui suas próprias limitações geométricas, que manifestam- se perante os dados na forma de uma função de seleção, ou seja, uma distribuição espacial de cada tipo de galáxia. A partir de um mapa de galáxias (real ou simulado), o principal objetivo desse trabalho foi descobrir como a função de seleção afeta alguns dos parâmetros cosmológicos que podem ser obtidos através de dados futuros de estrutura em larga escala. Portanto, propôs-se um método de Monte-Carlo com cadeias de Markov para estudar os efeitos decorrentes da inclusão dos parâmetros da função de seleção como nuisance parameters. Esse método consiste em combinar simulações de catálogos de galáxias, usando um espectro de potências teórico da matéria junto com um estimador ótimo, a fim de obter ambos espectros (teórico e observacional) e compará-los em uma verossimilhança Gaussiana-multivariada. O método de Monte-Carlo provou-se robusto e capaz de demonstrar os efeitos da função de seleção sobre as estimativas dos parâmetros cosmológicos, comprovando que o simples ato de marginalizar sobre os parâmetros não desejados pode levar a estimativas equivocadas na cosmologia em quesão. Finalmente, esse método foi aplicado nas estimações do parâmetro de Hubble (H0), na densidade de matéria escura (c) e em dois dos parâmetros da equação de estado da energia escura (w0 e wa) com o objetivo de prever tais efeitos para dados futuros do levantamento J-PAS com Galáxias Vermelhas Luminosas.
29
Rahmani, Donya. "Bayesian singular spectrum analysis with state dependent models". Thesis, Bournemouth University, 2017. http://eprints.bournemouth.ac.uk/29543/.
Testo completoAbstract (sommario):
The analysis of time series using Singular Spectrum Analysis has become an important area of statistics with application in a variety of fields such as economics, geophysics, engineering, medicine and many others. In fact, in this method there is no need to make any statistical assumptions such as the stationarity of the series or normality of the residuals. Therefore, SSA is recognised as an extremely practical tool which can be used to solve problems without considering any parametric model. At its core SSA depends on an eigenvector decomposition of the covariance matrix of a time series which may be utilised for forecasting via a linear recurrent formula. However, many time series exhibit structural breaks which interfere with a linear continuation of the time series although the underlying data generating process may not have changed. In addition, in a multivariate setting there is the added complication of combining time series. In this case the linear recurrence relationships of each time series may either reinforce each other or alternatively may lead to degraded forecasts. In this thesis a state dependent model is proposed under the assumption that if a system moves from one homogeneous state to another rapidly that this transition may be tracked using a Bayesian model in which the state transitions are state dependent. In addition, it is proven that for basic SSA the linear recurrent coe cients are biased and that this bias decays linearly with the samples. Empirically, the state dependent model shows far superior performance over two multivariate data sets. In the second part of the thesis component matching is examined. The core issue is how to identify which time series to group together without testing every possible combination. Geographical information resulted in superior forecasts on USA unemployment time series via a spatial SSA model. Subsequent research into data driven methods to group the time series concludes that a novel variant of the self organising map leads to a signi cant improvement over methods based on standard techniques like tensor analysis and joint diagonalisation.
30
Silva, Agampodige Emmanuel Diyanth Sirimal. "Theoretical advancements and applications in singular spectrum analysis". Thesis, Bournemouth University, 2016. http://eprints.bournemouth.ac.uk/25043/.
Testo completoAbstract (sommario):
Singular Spectrum Analysis (SSA) is a nonparametric time series analysis and forecasting technique which has witnessed an augment in applications in the recent past. The increased application of SSA is closely associated with its superior filtering and signal extraction capabilities which also differentiates it from the classical time series methods. In brief, the SSA process consists of decomposing a time series for signal extraction and then reconstructing a less noisy series which is used for forecasting. The aim of this research is to develop theoretical advancements in SSA, supported by empirical evidence to further promote the value, effectiveness and applicability of the technique in the field of time series analysis and forecasting. To that end, this research has four main contributions. Initially, given the reliance of this research towards improving forecasting processes, it is mandatory to compare and distinguish between the predictive accuracy of forecasts for statistically significant differences. The first contribution of this research is the introduction of a complement statistical test for comparing between the predictive accuracy of two forecasts. The proposed test is based on the principles of cumulative distribution functions and stochastic dominance, and is evaluated via both a simulation study and empirical evidence. Governments, practitioners, researchers and private organizations publish a variety of forecasts each year. Such forecasts are generally computed using multivariate models and are widely used in decision making processes given the considerably high level of anticipated forecast accuracy. The classical multivariate methods consider modelling multiple information pertaining to the same time period or with a time lag into the past. Multivariate Singular Spectrum Analysis (MSSA) is a relatively new and alternative technique for generating forecasts from multiple time series. The second contribution of this research is the introduction of a novel theoretical development which seeks to exploit the information contained in published forecasts (which represent data with a time lag into the future) for generating a new and improved (comparatively more accurate) forecast by taking advantage of the MSSA technique’s capability at modelling time series with different series lengths. In brief, the proposed multivariate theoretical development seeks to exploit the forecastability of forecasts by considering not only official and professional forecasts, but also forecasts obtained via other time series models. The productive application of SSA and MSSA depends largely on the selection of SSA and MSSA parameters, i.e. the Window Length, L, and the number of eigenvalues r which are used for decomposition and reconstruction of time series. Over the years, a variety of mathematically complex, time consuming and labour intensive approaches which require detailed knowledge on the theory underlying SSA have been proposed and developed for the selection of SSA and MSSA parameters. However, the highly labour intensive and complex nature of such approaches have not only discouraged the application of this method by those not conversant with the underlying theory, but also limited SSA and MSSA to offline applications. The third and final contribution of this research proposes new, automated and optimized, SSA and MSSA algorithms for the selection of SSA parameters and thereby enables obtaining optimal SSA and MSSA forecasts (optimized by minimising a loss function). This development opens up the possibility of using SSA and MSSA for online forecasting in the future.
31
Hawwari, Majd I. "Photon Beam Spectrum Characterization Using Scatter Radiation Analysis". University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1265986558.
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Isbiliroglu, Levent. "Strategy for Selecting Input Ground Motion for Structural Seismic Demand Analysis". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAU009/document.
Testo completoAbstract (sommario):
Les signaux accélérométriques enregistrés lors de l’occurrence d’un événement sismique est très large présentent une forte variabilité, par conséquent ils ne sont pas utilisé dans les analyse dynamiques de tenue sismique des structures. En effet, l’utilisation des accélérogrammes réels, pour les analyses dynamiques non linéaires, s’avère couteuse en termes de temps de calcul. La pratique courante prévoit la minimisation (voir suppression) de telle variabilité, mais les conséquences d’une telle opération sur la réponse des structures ne sont pas clairement indiquées. L’étude ci-présente a pour scope la quantification de l’impact des méthodes de sélection qui gardent la variabilité du signal sur les résultats de l’analyse de la réponse des structures (exprimée en termes d’engineering demand parameters EDPs). En particulier les questions suivantes seront investiguées :Quel est le niveau de variabilité des accélérogrammes réels et comment ce niveau est modifié par les techniques couramment utilisées ?Quelle est l’impact de la variabilité sur la réponse de plusieurs types de structures ?Pour un scénario sismique donné, un spectre cible est défini à partir de plusieurs équation de prédiction du mouvement sismique, sélection parmi celles disponibles en littérature. Les accélérogrammes sont sélectionnés à partir de quatre familles d’accélérogrammes, chacune relative à une méthode de modification : réels (enregistrés); mise à l’échelle (multiplication, par un facteur) ; calés aux spectres cibles avec large tolérance ; calés aux spectres cibles dans une plage de tolérance étroite.Chaque jeu de signaux est composé de cinq accélérogrammes et la sélection des signaux est faite en tenant compte de deux sources de variabilité : la variabilité au sein de chaque jeu de données (intraset), et la variabilité entre les différents jeux de données (interset) tous compatibles avec le même spectre cible. Les tests sur les EDPs menés sur les signaux accélérométriques réels mènent à la quantification de la variabilité naturelle (pour le scénario considéré). Les analyses basées sur les signaux réels sont utilisés comme benchmark afin d’évaluer non seulement de combien la distribution des EDPs (en termes de valeur moyenne et variabilité) est réduite par les différentes méthodes testées, mais aussi d’évaluer l’impact des choix de l’équation de prédiction du mouvement, des plages de tolérance, du nombre d’accélérogrammes constituant chaque jeu, du nombre de jeux, de le scope de l’analyse structurale et le modèle de structure.Ce travaille nous conduit à conclure que un seul jeu d’accélérogramme, tel qu’utilisé dans la pratique courante, est insuffisant pour assurer le niveau d’EDPs indépendamment de la méthode de modification utilisés, cela est lié à la variabilité des signaux et entre les jeux d’accélérogrammes. Les signaux réels, compatibles avec le spectre définis pour le scénario sismique, are l’option plus réaliste pour l’analyse dynamique non-linéaire ; si une méthode de modification du signal est nécessaire, la plus adaptées dépend du scope de l’analyse spectrale et du modèle. Le choix de l’équation de prédiction du mouvement sismique utilisée pour définir le spectre cible impacte significativement les caractéristiques des mouvements sismiques et des EDPs. Cette observation ne dépend pas de la stratégie de de modification du signalThe observed variability is very large among natural earthquake records, which are not consolidated in the engineering applications due to the cost and the duration. In the current practice with the nonlinear dynamic analysis, the input variability is minimized, yet without clear indications of its consequences on the output seismic behavior of structures. The study, herein, aims at quantifying the impact of ground motion selection with large variability on the distribution of engineering demand parameters (EDPs) by investigating the following questions:What is the level of variability in natural and modified ground motions?What is the impact of input variability on the EDPs of various structural types?For a given earthquake scenario, target spectra are defined by ground motion prediction equations (GMPEs). Four ground motion modification and selection methods such as (1) the unscaled earthquake records, (2) the linearly scaled real records, (3) the loosely matched spectrum waveforms, and (4) the tightly matched waveforms are utilized. The tests on the EDPs are performed on a record basis to quantify the natural variability in unscaled earthquake records and the relative changes triggered by the ground motion modifications.Each dataset is composed by five accelerograms; the response spectrum compatible selection is then performed by considering the impact of set variability. The intraset variability relates to the spectral amplitude dispersion in a given set, and the interset variability relates to the existence of multiple sets compatible with the target.The tests on the EDPs are performed on a record basis to quantify the natural variability in unscaled earthquake records and the relative changes triggered by the ground motion modifications. The distributions of EDPs obtained by the modified ground motions are compared to the observed distribution by the unscaled earthquake records as a function of ground motion prediction equations, objective of structural analysis, and structural models.This thesis demonstrates that a single ground motion set, commonly used in the practice, is not sufficient to obtain an assuring level of the EDPs regardless of the GMSM methods, which is due to the record and set variability. The unscaled real records compatible with the scenario are discussed to be the most realistic option to use in the nonlinear dynamic analyses, and the ‘best’ ground motion modification method is demonstrated to be based on the EDP, the objective of the seismic analysis, and the structural model. It is pointed out that the choice of a GMPE can provoke significant differences in the ground motion characteristics and the EDPs, and it can overshadow the differences in the EDPs obtained by the GMSM methods
33
Snoswell, Mark Andrew. "Novel approaches to large scale protein purification and analysis /". Title page, contents and summary only, 1990. http://web4.library.adelaide.edu.au/theses/09PH/09phs673.pdf.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of Adelaide, Dept. of Biochemistry, 1992.Cover title: Novel approaches to protein purification and analysis: counter-current electrophoretic filtering: spectral enhancement. Spine title: Protein purification and analysis. Includes bibliographical references.
34
Harvey, Pierre Dominique. "Applications of vibrational spectroscopy and NMR spin-lattice relaxation time measurements to organometallic and organic molecular crystals". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=73986.
Testo completo
35
Bennia, Abdelhak. "Optimal filters for deconvolution of transient signals in the presence of noise". Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-09162005-115009/.
Testo completo
36
Wentzel, Mauritz. "Identification and characterization of novel oncology related platinum complexes using chromatographic and mass spectrometric techniques". Thesis, Nelson Mandela Metropolitan University, 2008. http://hdl.handle.net/10948/715.
Testo completoAbstract (sommario):
In this thesis mass spectral and chromatographic techniques were developed and applied to identify and characterise numerous novel platinum(II) and (IV) compounds designed as anticancer agents. In a novel method for the synthesis of cis-oxalato(trans- -1,2- cyclohexanediamine)platinum(II) or oxaliplatin these techniques could be applied to differentiate between the molecular complex and the autoionised analogue (viz. Ptdach2 2+Ptox2 2-). In another novel synthetic method for the same compound the ligand exchange reactions at various temperatures could be investigated and kinetic curves obtained served to illuminate the chemistry involved, indicating the role of small amounts of water in the essentially non-aqueous solvent systems dmf and isoamyl alcohol respectively. These allowed ligand exchange without resulting in hydrolyses even up to 85°C. The ionisation rate of divalent platinum halide complexes was determined for various amine ligands as well as N-S chelate ligands. A comparison of these could suggest why N-S complexes have poor anticancer action. Ionisation was not only studied for neutral molecular species but also for monocationic ones. Relationships could be found with stereochemical aspects of the chelates used. By investigating results of EV-CAD studies thermodynamic data could be obtained which indicated that bond strength decreases from chloro to iodo analogues although extent of ionisation in aqueous solution, i.e kinetic stability, is the reverse. Products formed by the reaction of NO2 gas with Platinum(II) compounds could be identified and separated which greatly contributed to the understanding of the chemistry involved in the formation of mononitro platinum(IV) complexes. Some of these proved to have exceptional anticancer properties. Studies of the interaction of thiol containing biomolecules were performed as a function of time. The results contributed to the understanding of the action of the anticancer agents.
37
Yilmaz, Nihal. "Spectral Characteristics Of Wind Waves In The Eastern Black Sea". Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608614/index.pdf.
Testo completoAbstract (sommario):
Wind waves are highly complex, random phenomena. One way to describe the irregular nature of the sea surface is the use of wave energy spectrum. Spectral information for wind waves in the Black Sea is extremely limited. Knowledge on spectral characteristics of wind waves would contribute to scientific, engineering and operational coastal and marine activities in the Black Sea. The aim of the present thesis is to investigate characteristics of wind wave spectra for the Eastern Black Sea. This would allow detailed understanding of the nature of the waves occurring in this enclosed basin. Long-term wave measurements obtained by directional buoys deployed offshore at Sinop, Hopa and Gelendzhik were utilized as the three sets of wave data. Records were analyzed to identify them as uni-modal or multi-modal spectra, and occurrences of spectral peaks were computed. Single peaked spectra were studied as belonging to fully arisen or developing sea states. Model parameters of JONSWAP and PM spectra were estimated for the observed spectra by using a least square error method. The records of developing seas were further analyzed to select the ones belonging to stable wind conditions. Fetch dependencies of non-dimensional spectral variables, mean parameters of JONSWAP model spectrum and the envelop of dimensionless spectra were investigated for this data sub-set.
38
López, Benítez Miguel. "Spectrum usage models for the analysis, design and simulation of cognitive radio networks". Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/33282.
Testo completoAbstract (sommario):
The owned spectrum allocation policy, in use since the early days of modern radio communications, has been proven to effectively control interference among radio communication systems. However, the overwhelming proliferation of new operators, innovative services and wireless technologies during the last years has resulted, under this static regulatory regime, in the depletion of spectrum bands with commercially attractive radio propagation characteristics. An important number of spectrum measurements, however, have shown that spectrum is mostly underutilized, thus indicating that the virtual spectrum scarcity problem actually results from static and inflexible spectrum management policies rather than the physical scarcity of radio resources. This situation has motivated the emergence of Dynamic Spectrum Access (DSA) methods based on the Cognitive Radio (CR) paradigm, which has gained popularity as a promising solution to conciliate the existing conflicts between spectrum demand growth and spectrum underutilization. The basic underlying idea of DSA/CR is to allow unlicensed (secondary) users to access in an opportunistic and non-interfering manner some licensed bands temporarily unoccupied by the licensed (primary) users.
Due to the opportunistic nature of this principle, the behavior and performance of a DSA/CR network depends on the spectrum occupancy patterns of the primary system. A realistic and accurate modeling of such patterns becomes therefore essential and extremely useful in the domain of DSA/CR research. The potential applicability of spectrum usage models ranges from analytical studies to the design and dimensioning of secondary networks as well as the development of innovative simulation tools and more efficient DSA/CR techniques. Spectrum occupancy modeling in the context of DSA/CR constitutes a rather unexplored research area. This dissertation addresses the problem of modeling spectrum usage in the context of DSA/CR by contributing a comprehensive and holistic set of realistic models capable to accurately capture and reproduce the statistical properties of spectrum usage in real radio communication systems in the time, frequency and space dimensions.
The first part of this dissertation addresses the development of a unified methodological framework for spectrum measurements in the context of DSA/CR and presents the results of an extensive spectrum measurement campaign performed over a wide variety of locations and scenarios in the metropolitan area of Barcelona, Spain, to identify potential bands of interest for future DSA/CR deployments. To the best of the author's knowledge, this is the first study of these characteristics performed under the scope of the Spanish spectrum regulation and one of the earliest studies in Europe. The second part deals with various specific aspects related to the processing of measurements to extract spectrum occupancy patterns, which is largely similar to the problem of spectrum sensing in DSA/CR. The performance of energy detection, the most widely employed spectrum sensing technique in DSA/CR, is first assessed empirically. The outcome of this study motivates the development of a more accurate theoretical-empirical performance model as well as an improved energy detection scheme capable to outperform the conventional method while preserving a similar level of complexity, computational cost and application. The findings of these studies are finally applied in the third part of the dissertation to the development of innovative spectrum usage models for the time (in discrete- and continuous-time versions), frequency and space domains. The proposed models can been combined and integrated into a unified modeling approach where the time, frequency and space dimensions of spectrum usage can simultaneously be reproduced, thus providing a complete and holistic characterization of spectrum usage in real systems for the analysis, design and simulation of the future DSA/CR networks.
39
Moalusi, Matlhodi Salamina. "Selected applications of sequential injection analysis". Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-08212007-155923.
Testo completo
40
Van, Wyck Neal Edward. "MULTIPHOTON SPECTROSCOPY OF THIN FILMS AND SURFACES (NONLINEAR, WAVEGUIDES, INTERFACES)". Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/291294.
Testo completo
41
Veltkamp, David James. "Energy dependent ion scattering spectroscopy : a chemometric study of its analytical utility /". Thesis, Connect to this title online; UW restricted, 1986. http://hdl.handle.net/1773/8584.
Testo completo
42
Mustonen, M. (Miia). "Analysis of recent spectrum sharing concepts in policy making". Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526216645.
Testo completoAbstract (sommario):
Abstract During the last couple of decades a lot of research efforts have been spent on developing different spectrum sharing concepts. As the traditional regulatory methods for spectrum allocation are proving inadequate in responding to a growing need for mobile spectrum in a timely manner and finding spectrum for exclusive use is getting increasingly difficult, the political atmosphere is also becoming more and more receptive to new innovative spectrum sharing concepts that increase the efficiency of spectrum use. These concepts also provide regulatory authorities an opportunity to fundamentally change the current major operator driven mobile market and thereby to allow new players and innovative services to surface. However, there is still a gap between the work done by the research community and the work of the regulatory authorities. In this thesis, the aim is to clarify the reasons behind this gap by analysing three prevailing regulatory spectrum sharing concepts: Licensed Shared Access, the three-tier model and TV white space concept. As different stakeholders involved in spectrum sharing – the incumbent user, the entrant user and the regulatory authority – have very diverse roles in spectrum sharing, their incentives and key criteria may vary significantly. In order for a spectrum sharing concept to have a chance in a real life deployment, all these perspectives need to be carefully considered. In fact, a feasible spectrum sharing concept is a delicate balance between the viewpoints of different stakeholders, not necessarily the one offering the most efficient spectrum utilization. This thesis analyses spectrum sharing concepts from all these perspectives and as a consequence unveils the common process model for implementing a spectrum sharing concept in real life, highlighting the distinct roles of different stakeholders in its phasesTiivistelmä Parin viimeisen vuosikymmenen aikana tutkimusyhteisö on kehittänyt valtavasti eri käsitteitä ja tuloksia taajuuksien yhteiskäyttöön. Matkapuhelinoperaattoreiden nopeasti kasvavan tiedonsiirto- ja taajuustarpeen myötä myös poliittinen ilmapiiri on muuttunut vastaanottavaisemmiksi uusille jaetuille taajuuksienkäyttömalleille, joilla voidaan sekä lisätä taajuuksien käytön tehokkuutta että mahdollistaa uusien toimijoiden ja innovatiivisten palvelujen kehitys. Taajuuksien yhteiskäyttömalleihin liittyvä tutkimustyö ei kuitenkaan usein palvele suoraan taajuusviranomaisten tarpeita. Tämän työn tavoitteena on selvittää syitä tähän kolmen vallitsevan joustavan taajuuksienkäyttökonseptin avulla: lisensoidun taajuuksien yhteiskäyttömallin, kolmitasoisen taajuuksien yhteiskäyttömallin ja TV kaistojen yhteiskäyttömallin. Eri toimijoilla on hyvin erilaiset roolit taajuuksien yhteiskäytössä ja siksi sekä heidän kannustimensa että keskeiset kriteerit voivat olla hyvin erilaiset. Käytäntöön sopiva jaetun taajuudenkäytön malli onkin usein kompromissi eri näkemysten omaavien toimijoiden kesken, ei välttämättä taajuuksien käytöltään tehokkain vaihtoehto. Tässä työssä analysoidaan eri taajuuksien yhteiskäyttömalleja sekä eri toimijoiden näkökulmia. Analyysin tuloksena luodaan yleinen prosessimalli taajuuksien yhteiskäyttömallien toteutukselle sekä identifioidaan eri toimijoiden roolit sen eri vaiheissa
43
Liggins, Florence. "The spectrum and term analysis of singly-ionised manganese". Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/59134.
Testo completoAbstract (sommario):
This thesis reports on the term analysis of singly-ionised manganese carried out in order to improve the accuracy and completeness of available Mn II atomic wavelengths and energy levels, for astrophysical applications. An extensive analysis of the Mn spectrum was carried out using high-resolution Fourier Transform (FT) spectra, supplemented with grating measurements, of Mn(Ne) and Mn(Ar) hollow cathode discharge sources, over the range 1820 – 121728 cm-1. The analysis of these spectra has resulted in accurate wavelength measurements for a total of 2360 Mn II lines of which 1219 are measured through FTS. These wavelengths are given to at least an order of magnitude greater accuracy compared with previous measurements. Energy level values have been revised for a total of 477 levels with typical uncertainties found to ~few mK (0.001 cm-1). In addition, 27 new energy level values of Mn II have been found from which 213 Mn II lines have been newly classified. This analysis has also enabled 56 Mn II energy levels, previously established through observation of stellar spectra alone, to be verified using laboratory-measured high-resolution FTS wavelengths.
44
Armour, W. "An analysis of the hadronic spectrum from lattice QCD". Thesis, Swansea University, 2004. https://cronfa.swan.ac.uk/Record/cronfa42952.
Testo completoAbstract (sommario):
In chapter one I begin by discussing the basic ideas of quantum field, theory (QFT). I provide a review of symmetries in physics and then move on to discuss the quark model. Chapter two is a review of lattice gauge theory with particular attention paid to lattice QCD. I begin by discussing lattice QCD and then discuss some of the associated problems. I move on to discuss gauge fields on the lattice along with free lattice fermions. I then use this to define the lattice QCD action. I conclude this chapter by discussing how to reproduce the correct continuum physics. Chapter three discusses the basic numerical techniques employed in lattice simulations. I review methods for putting particles onto the lattice and conclude with a discussion of how to fit the resulting data. Chapter four reviews symmetries of the QCD Lagrangian, various forms of symmetry breaking in physics, the PCAC relation, the Goldberger-Treiman relation and the spontaneous breakdown of the axial symmetry. I move on to discuss sigma models and arrive at a basic chiral perturbation theory.
45
Xie, Qing Yan. "Performance Analysis of Opportunistc Spectrum Access on Cognitive Radio". University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1273173530.
Testo completo
46
Bie, Yifeng. "Functional principal component analysis based machine learning algorithms for spectral analysis". Thesis, 2021. http://hdl.handle.net/1828/13372.
Testo completoAbstract (sommario):
The ability to probe molecular electronic and vibrational structures gives rise to
optical absorption spectroscopy, which is a credible tool used in molecular quantification and classification with high sensitivity, low limit of detection (LoD), and
immunity to electromagnetic noises. Spectra are sensitive to slight analyte variations, so they are often used to identify a sample’s components. This thesis proposes
several methods for quick classification and quantification of analysts based on their
absorbance spectra. functional Principal Component Analysis (fPCA) is employed
for feature extraction and dimension reduction. For 1,000-pixel spectra data, fPCA
can capture the majority variance with as few output scores as the number of expected analytes. This reduces the amount of calculation required for the following
machine learning algorithms. Further, the output scores are fed into XGBoost and
logistic regression for classification, and fed into XGBoost and linear regression for
quantification.
Our models were tested on both synthesized datasets and experimentally acquired
dataset. Our models demonstrated similar performance compared to deep learning
but with much faster processing speeds. For the synthesized 30 dB dataset, our
model XGBoost with fPCA could reach a micro-averaged f1 score of 0.9551 ± 0.0008,
while FNN-OT [1] could obtain 0.940±0.001. fPCA helped the algorithms extract the
feature of each analyte; furthermore, the output scores nearly had a linear relationship
with their concentrations. It was much easier for the algorithm to find the mapping
function between the inputs and the outputs with fPCA, which shortened the training
and testing time.Graduate
47
Wu, Jin-Tzuoh, e 吳金座. "Spectrum Analysis on Time Domain". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/22559435038823006617.
Testo completo
48
Ning, Chia-Ching, e 寧家慶. "Optimization of Harmonic Spectrum Analysis". Thesis, 1999. http://ndltd.ncl.edu.tw/handle/00025188122400842980.
Testo completoAbstract (sommario):
碩士國立中山大學
電機工程學系
87
Traditionally, the analysis technique of harmonic has been done by Fast Fourier Transform (FFT). It has advantage of fast computation but many limitations. Consequently, this paper proposes a method to improve FFT errors significantly. This method has been divided into three stages. Firstly, the paper uses a set of simple formula to obtain frequent and amplitude of signal. Secondly, find optimized parameters to make new spectrum match with signal characteristic. Finally, make using of the set of optimized parameters to adjust original spectrum, which define it adjustable spectrum. By means of the three stages, the optimization of spectrum to signal is achieved. Moreover, we compare each stage with traditional FFT to prove its advantages and benefits. The proposed method has been validated and evaluated by four practical examples.
49
Bing, Zhou. "Crosshole resistivity and acoustic velocity imaging : 2.5-D helmholtz equation modeling and inversion / by Zhou Bing". Thesis, 1998. http://hdl.handle.net/2440/19295.
Testo completoAbstract (sommario):
Bibliography: leaves 239-248.viii, 248 leaves : ill. ; 30 cm.
Shows that the normalised Fourier/Hartley spectral data can be used for imaging when the seismic source wavelet is unknown.
Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics, 1998
50
Cheng, Kai-Yin, e 鄭凱尹. "Investigating image velocimetry by spectrum analysis". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/83993366579606097537.
Testo completoAbstract (sommario):
碩士國立臺灣大學
土木工程學研究所
103
In recent years, debris-flow hazards occur frequently in Taiwan and cause casualties and property loss in many residential areas. In order to minimize the effect of such hazard, it requires more understanding of debris-flow’s behavior. The research is aim to develop an innovative image velocimetry, using spectrum analysis in the flow field. We took both celerity and water velocity into account to analyze the signal reflected from the water surface. After the images were transformed to gray level, the gray value represents the information of fluid motion. We first consider the spatial information of flow field as composite waveform and then transfer it to the frequency domain by using Fourier transformation. Afterwards, the dispersion relationship of wave theory was adopted to analyze the signal. For doing the velocity analysis, we first capture the signal of deep water wave and applied the inverse Fourier transformation to turn it into spatial domain. In this research, the issue existing in current image velocimetry that the flow field lacks of analyzable particle can be improved. However, there is still a room for waveform identification. The average error is 26% comparing to the results obtained via the instrument.