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An, Li. "Water-fat imaging and general chemical shift imaging with spectrum modeling." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0032/NQ38848.pdf.
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Daudé, Pierre. "Quantification du tissu adipeux épicardique à haut champ par IRM-Dixon, pour le phénotypage de la cardiomyopathie diabétique." Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0333.
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L’amélioration de la prise en charge des complications cardiaques dans les maladies métaboliques, obésité et diabète, est un enjeu majeur de notre société. La mesure du tissu adipeux épicardique (TAE), dépôt de graisse attaché au cœur, est un élément diagnostique émergent et prometteur pour identifier les patients à risque. Nous avons développé l’automatisation de cette mesure sur des images IRM de routine par apprentissage profond. Puis, une technique IRM innovante a été proposée pour mesurer et caractériser le TAE en 3D, réunissant : une acquisition en respiration libre, une reconstruction des images robuste au mouvement cardio-respiratoire et aux imperfections de l’IRM, un algorithme de caractérisation de la graisse optimisé et validé et la connaissance de la composition d’échantillons ex-vivo de TAE. L’ensemble permet la caractérisation in vivo et non-invasive du TAE, élément diagnostique novateur du risque cardio-métaboliqueImproving the management of cardiac complications in metabolic diseases, obesity and diabetes, is a major challenge for our society. The measurement of epicardial adipose tissue (EAT), a fat depot attached to the heart, is an emerging and promising diagnosis to identify patients at risk. We developed the automation of this measurement on routine MRI images by deep learning. Then, an innovative MRI technique was proposed to measure and characterize the EAT in 3D, combining: a free-breathing acquisition, an image reconstruction robust to cardio-respiratory motion and MRI imperfections, an optimized and validated fat characterization algorithm and the knowledge of the composition of ex-vivo EAT samples. Together, this allows for in vivo, non-invasive characterization of EAT, a novel diagnosis for cardiometabolic risk
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Kharroubi, Hassane. "Étude du pouvoir réflecteur de monocristaux uniaxes et biaxes dans l'infrarouge lointain." Nancy 1, 1994. http://www.theses.fr/1994NAN10108.
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L'étude du pouvoir réflecteur (r) et de la transmission (t) des milieux anisotropes et absorbants dans l'infrarouge lointain nous a conduit a présenter des expressions directement programmables des relations permettant la détermination des constantes optiques, l'indice de réfraction n et l'indice d'absorption k à partir des mesures expérimentales de r et de t. Nous avons établi les expressions des facteurs de réflexion et de transmission pour les deux polarisations possibles de l'onde, en fonction de l'angle d'incidence. L'étude est limitée au cas de la propagation d'une onde plane dans les plans principaux du cristal. Nous abordons ensuite le cas de la lame à faces parallèles qui représente physiquement nos échantillons. Les facteurs de réflexion et de transmission sont mesurés dans l'infrarouge lointain de 10 à 600 cm##1 en lumière polarisée pour des températures comprises entre 7 et 300 k. Pour cette étude nous avons choisi un cristal biaxe, le nitrite de sodium et deux cristaux uniaxes, la cassitérite et le quartz. La comparaison des résultats expérimentaux et des valeurs calculées nécessite la connaissance de la fonction diélectrique. Nous utilisons la forme factorisée de la fonction diélectrique. Les valeurs initiales des paramètres d'ajustage sont déterminées par une analyse de Kramers-Kronig du spectre de réflexion sous incidence normale. La mesure simultanée du pouvoir réflecteur et de la transmission de la lame nous permet d'apporter une correction pour déterminer la valeur vraie du pouvoir réflecteur des cristaux, valeur nécessaire pour les calculs de physique du solide
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Cheraghi, Parisa. "Fast and accurate spectrum sensing low signal noise ratio environment." Thesis, University of Surrey, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581799.
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Opportunistic Spectrum Access (OSA) [1] promises tremendous gain in improving spectral efficiency. The main objective of OSA is to offer the ability of identifying and exploiting the under-utilised spectrum in an instantaneous manner in a wireless device, without any user intrusion. Hence, the initial requirement of any OSA device is the ability to perform spectrum sensing. Local narrow-band spectrum sensing has been quite well investigated in the literature. However, it is realised that existing schemes can hardly meet the requirements of a fast and accurate spectrum sensing particulariy in very low signal-to-noise-ratio (SNR) range without introducing high complexity to the system. Furthermore, increase in the spectrum utilisation calls for spectrum sensing techniques that adopt an architecture to simultaneously search over multiple frequency sub-bands at a time. However, the literature of sub-band spectrum sensing is rather limited at this time. The main contributions of this thesis is two-fold: First a clusterd-based differential energy detection for local sensing of multi- carrier based system is proposed. The proposed approach can form fast and reliable decision of spectrum availability even in very low SNR environment. The underlying initiative of the proposed scheme is applying order statistics on the clustered differential Energy Spectral Density (ESD) in order to exploit the channel frequency diversity inherent in high data-rate communications. Second contribution is three-fold: 1) re-defining the objective of the sub- band level spectrum sensing device to a model estimator, 2) deriving the optimal model selection estimator for sub-band level spectrum sensing for fixed and variable number of users along with a sub-optimal solution based on Bayesian statistical modelling and 3) proposing a practical model selection estimator with relaxed sample size constraint and limited system knowledge for sub-band spectrum sensing applications in Orthogonal Frequency-Division Multiple Access (OFDMA) systems. The result obtained showed that through exploitation of the channel frequency selectivity the performance of the stat-of-the-art spectrum sensing techniques can be significantly improved. Furthermore, by modelling the sub-band level spectrum sensing through model estimation allows for new spectrum sensing approach. It was proved both analytically and through simulations that the proposed approach have significantly extended to state-of-the-art spectrum sensing. Key words: Differential, energy detection, low signal-to- noise ratio (SNR), multi- carrier, opportunistic spectrum access, spectrum sensing.
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Abdel-Rahman, Mohammad Jamal. "Robust Cognitive Algorithms For Fast-Varying Spectrum-Agile Wireless Networks." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/338872.
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Wireless communications have experienced tremendous growth in the last decade, which has placed significant demand for RF spectrum, leading to spectrum "crunch." Driven by numerous studies that revealed the significant under-utilization of many licensed channels in the VHF and UHF bands, a new paradigm for spectrum sharing has emerged in the past decade. In this paradigm, wireless devices (a.k.a. secondary users) are allowed to operate opportunistically in certain licensed bands without interfering with the licensed users (a.k.a. primary users). The realization of this new communication paradigm necessitates the design of a new generation of smart, adaptable, and programmable radios, called cognitive radios. Enabling opportunistic operation requires addressing various challenges including device coordination, resource allocation, channel monitoring, and various security issues. Specifically, secondary users are particularly vulnerable to node compromise and malicious jamming attacks. In this dissertation, we first develop several rendezvous algorithms for establishing unicast as well as multicast communication links in opportunistic spectrum access networks. The developed rendezvous algorithms are shown to be robust to node compromise attacks. Second, we study the anti-jamming rendezvous problem in the presence of an insider attack. We develop a combinatorial game-theoretic framework to capture the interactions between the rendezvousing nodes and the insider jammer. Third, to account for the dynamism of primary users, we propose novel stochastic resource allocation schemes under channel-quality uncertainty. The proposed schemes support channel bonding and aggregation and account for adjacent channel interference by introducing guard-bands. Fourth, to prevent interference with primary users, we design an optimal spectrum-sensing algorithm that achieves high detection accuracy and low false-alarm rate. Finally, we present an application of using cognitive radios for jamming mitigation in satellite communications. Extensive simulations are conducted to demonstrate the effectiveness and robustness of the proposed algorithms.
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Li, King Fai. "Ultra-fast spectroscopy investigation on organic molecules two photon absorption." HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/911.
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Bo, Zhang, Ren Yixun, Yang Dongkai, and Zhang Qishan. "FAST ACQUISITION ALGORITHM FOR HYBRID DS/FH RECEIVER." International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604569.
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ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, NevadaThis paper introduced a fast scanning and waiting acquisition method for a DS/FH receiver used in the telemetry field. Mathematic model of the hybrid DS/FH system’s acquisition process is given and discussed. The average acquisition time expression using this method and generalized average acquisition time formula is derived also. The validity of the proposed algorithm is verified after simulation. In the circumstances of Additive Gauss White Noise for the channel, simulation result at Ec/N0= -15dB shows that the average acquisition time is decreased almost 4 times than that of waiting and searching method.
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Emmett, John Carter Alfred. "A standard neutron spectrum source of application to fast reactor physics." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312126.
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Jian-zhong, Qi, Gong Yan, and Song Peng. "Realization of Fast Acquisition for Spread Spectrum Signal Based on FFT." International Foundation for Telemetering, 2011. http://hdl.handle.net/10150/595763.
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ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, NevadaAcquisition based on Fast Fourier Transform (FFT) can acquire Pseudo-random code phase quickly and improve the performance of the satellite navigation receivers. In the paper Real-time receiver adopts the FPGA to realize the function of FFT and uses DSP processor to control the implementation process of Acquisition. For increasing the sensitivity of Acquisition incoherent accumulation were used in the process. Also, in the paper we have discussed the process method for decreasing the negative influence of signal power changes and carrier's Doppler frequency.
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Rosenthal, Glenn, and Thomas Salley. "USING THE FFT FOR DSP SPECTRUM ANALYSIS: A TELEMETRY ENGINEERING APPROACH." International Foundation for Telemetering, 1990. http://hdl.handle.net/10150/613797.
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International Telemetering Conference Proceedings / October 29-November 02, 1990 / Riviera Hotel and Convention Center, Las Vegas, NevadaThe Fast Fourier Transform (FFT) converts digitally sampled time domain data into the frequency domain. This paper will provide an advanced introduction for the telemetry engineer to basic FFT theory and then present and explain the different user preprocessing options that are available when using the FFT. These options include: using windowing functions, “zero filling” for frequency data interpolation, and setting the frequency resolution of the FFT resultant spectrum,
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Benison, Benjamin David. "Receiver structures for a fast-frequency-hopped spread spectrum mobile communications system." Thesis, University of Canterbury. Electrical and Electronic Engineering, 1999. http://hdl.handle.net/10092/5961.
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Code Division Multiple Access Technologies have recently received considerable attention as a means of increasing the capacity of a mobile network. They inherently provide for increased system performance together with some resistance to the effects of the mobile channel. While direct sequence spread spectrum systems have been extensively investigated the alternative fast frequency hopped systems have largely been ignored. This thesis considers fast frequency hopped spread spectrum technology as an access method for providing a mobile communication network. Such systems have been previously used by the military to provide reliable communication between a number of parties, in a hostile interference limited channel. The multiple-access mobile communication channel has many similarities to the channel encountered in the military applications.
This thesis examines the effect of the interference encountered in the mobile multiple-access communication channel on the transmitted signal. Suitable receiver structures for the channel are then derived which provide for efficient communication in the interference limited channel. These receivers operate to minimise the effect of the interference on the received signal. The multiple-access interference encountered in the channel limits the performance of conventional receivers designed to detect a single user's transmitted signal. This thesis derives a model for the effect of the multiple-access interference on these receivers, A model is provided for the effects of the time-varying frequency-selective multi-path fading encountered by the proposed system in the channel.
The design of appropriate receivers for the mobile channel is then considered. Receivers are developed which minimise the effect of interference on the received signal. A prediction process is employed to minimise the effects of the multi-path fading on the received signals. An optimum multi-user receiver is developed. To minimise the effect of the multiple-access interference the optimum receiver simultaneously detects each of the signals present in the channel. The complexity of this receiver limits its application.
The derivation is then extended to obtain a less complex sub-optimum receiver based on the optimal structure. This receiver employs an averaging process to approximate the effect of the multiple-access interference on the desired user's signal. A prediction process is again employed to minimise the effect of the multi-path fading channel on the received signals. The effect of the multi-path channel on the interfering users' signals is included in the averaging process.
The performance of the receivers is evaluated through simulation. In the multiple-access, multi-path channel the performance of the sub-optimum receiver is found to approach that of the optimum receiver when there is a low level of multiple-access interference. As this interference increases the performance of the receiver suffers.
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Scaife, Bradley J. "DOPPLER SHIFTED SPREAD SPECTRUM CARRIER RECOVERY USING REAL-TIME DSP TECHNIQUES." International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/607365.
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International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, CaliforniaIn any satellite communication, the Doppler shift associated with the satellite’s position and velocity must be calculated in order to determine the carrier frequency. If the satellite state vector is unknown then some estimate must be formed of the Doppler-shifted carrier frequency. One elementary technique is to examine the signal spectrum and base the estimate on the dominant spectral component. If, however, the carrier is spread (as in most satellite communications) this technique may fail unless the chip rate-to-data rate ratio (processing gain) associated with the carrier is small. In this case, there may be enough spectral energy to allow peak detection against a noise background. In this paper, we present a method to estimate the frequency (without knowledge of the Doppler shift) of a spread-spectrum carrier assuming a small processing gain and binary-phase shift keying (BPSK) modulation. Our method relies on a simple, averaged discrete Fourier transform along with peak detection. We provide simulation results indicating the accuracy of this method. In addition, we will describe an all-digital hardware design based around a Motorola DSP56303 and high-speed A/D which implements this technique in real-time. The hardware design is to be used in NMSU’s implementation of NASA’s demand assignment, multiple access (DAMA) service.
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Hietanen, Jorma. "Investigations on far infrared spectra of acetylenes." Oulu : University of Oulu, 1986. http://catalog.hathitrust.org/api/volumes/oclc/15356036.html.
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Wellard, Stanley James. "Tropospheric Spectrum Estimations Comparing Maximum Likelihood with Expectation Maximization Solutions and Fast Fourier Transforms." DigitalCommons@USU, 2007. https://digitalcommons.usu.edu/etd/264.
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The FIRST program (Far Infrared Spectroscopy in the Troposphere) was created as an Instrument Incubator Program (IIP) by NASA Langley to demonstrate improved technology readiness levels (TRLs) for two technologies needed in the design of new imaging Fourier transform spectrometers (IFTS). The IIP IFTS was developed at the Space Dynamics Laboratory and flown to an altitude of 103,000 feet on an instrumented NASA balloon payload. The sensor collected approximately 15,000 interferograms during its 6-hour flight. Fourier transforms (FFT) produced acceptable results except for noise equivalent temperature differences (NETD) that were five times higher than goal and inconclusive transforms at seven strong absorption features.
An alternate transform technique, maximum likelihood estimation (MLE), was implemented to improve spectral estimations at the absorptions and to improve the NETD for the sensor. Iterative expectation-maximization (EM) algorithms provide numerical solutions for the MLE.
Four combinatorial forms of the EM algorithm were developed. Forms of the EM algorithm were developed to optimize amplitude estimations as a function of assumed noise distributions. 'Direct' and 'indirect' EM forms were developed to process the asymmetrical interferograms recorded by the FIRST sensor.
The direct method extends the standard even (cosine) EM algorithm to simultaneously transform both the sine and cosine components of the interferogram. The indirect method, uses Fourier and inverse Fourier transforms as pre-processors to convert the measured asymmetrical interferograms to even (cosine) interferograms.
Using the indirect Gaussian EM form improved the measured NETD by approximately twenty percent between 100 and 700 wavenumbers. For wavenumbers less than 100 or greater than 700, the improvement increased to a factor of at least two out to 1500 wavenumbers.
The indirect Gaussian produced inconclusive results in the areas of high absorption because of large bias errors introduced by the FFT/IFFT pre-processing. The indirect method was found to be inadequate for estimating spectra at the deep absorptions. The direct EM method, on the other hand, has the potential to produce improved amplitude estimations at the absorptions since there are no inherent biases in the algorithm's initial conditions at a cost in computer resources and execution times that are four times those needed for the indirect method.
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Fabre, David H. "Parameterized Spectral Bathymetric Roughness Using the Nonequispaced Fast Fourier Transform." ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/2070.
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The ocean and acoustic modeling community has specifically asked for roughness from bathymetry. An effort has been undertaken to provide what can be thought of as the high frequency content of bathymetry. By contrast, the low frequency content of bathymetry is the set of contours. The two-dimensional amplitude spectrum calculated with the nonequispaced fast Fourier transform (Kunis, 2006) is exploited as the statistic to provide several parameters of roughness following the method of Fox (1996). When an area is uniformly rough, it is termed isotropically rough. When an area exhibits lineation effects (like in a trough or a ridge line in the bathymetry), the term anisotropically rough is used. A predominant spatial azimuth of lineation summarizes anisotropic roughness. The power law model fit produces a roll-off parameter that also provides insight into the roughness of the area. These four parameters give rise to several derived parameters.
Algorithmic accomplishments include reviving Fox’s method (1985, 1996) and improving the method with the possibly geophysically more appropriate nonequispaced fast Fourier transform. A new composite parameter, simply the overall integral length of the nonlinear parameterizing function, is used to make within-dataset comparisons.
A synthetic dataset and six multibeam datasets covering practically all depth regimes have been analyzed with the tools that have been developed.
Data specific contributions include possibly discovering an aspect ratio isotropic cutoff level (less than 1.2), showing a range of spectral fall-off values between about -0.5 for a sandy- bottomed Gulf of Mexico area, to about -1.8 for a coral reef area just outside of the Saipan harbor. We also rank the targeted type of dataset, the best resolution gridded datasets, from smoothest to roughest using a factor based on the kernel dimensions, a percentage from the windowing operation, all multiplied by the overall integration length.
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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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Basden, Alastair Graham. "A fast spectro-interferometric sensor for the COAST." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616221.
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Wishnow, Edward Hyman. "Far-infrared absorption by liquid nitrogen and liquid oxygen." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25072.
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This thesis examines the collision induced, far-infrared absorption of homonuclear diatomic molecules. These molecular processes are relevant in the astrophysical environments of planetary atmospheres and galactic molecular clouds, and a brief survey of far-infrared measurements of these regions is presented. The theory of collision induced absorption by molecular rotational transitions is reviewed and a calculation is made of the quadrupolar induced, single rotational transition absorption line intensities of the nitrogen and oxygen molecules. The far-infrared absorption spectra of liquid nitrogen and liquid oxygen at 77K, over the frequency range 5 to 70 cm⁻¹ , have been measured. The far-infrared spectrum of liquid oxygen has not previously been reported. The present work includes the design of a low temperature, multiple pass, far-infrared absorption cell intended for low temperature, low density gas measurements. The effect of diffraction on the cell's maximum attainable optical path length, and a model used to estimate the anticipated liquid helium consumption are discussed.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Thibodeau, Brian Michael. "A Framework for Cooperative Wideband Spectrum Sensing Using the Robust Fast Fourier Aliasing-based Sparse Transform." Master's thesis, Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/389212.
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Electrical and Computer EngineeringM.S.E.E.
This research considers the problem of cooperatively identifying the active bands in a wideband spectrum using the sparse Fast Fourier Transform (sFFT). Existing research has focused primarily on Compressed Sensing (CS) and Multi-Coset (MC) sampling, but recent developments in the sFFT have shown that a sparsely occupied spectrum can be efficiently reconstructed using multiple co-prime analog-to-digital converters (ADC) that sample below the Nyquist rate. Specifically, this research utilizes the Robust Fast Fourier Aliasing-based Sparse Transform (R-FFAST) and extends this algorithm for use in cooperative wideband spectrum sensing (CWSS). Unlike previous approaches that implement the sFFT for spectrum sensing, the R-FFAST framework was developed and analyzed using the mutual coherence and the restricted isometry property (RIP) from CS theory. This leads to reliable support estimation in the presence of additive white Gaussian noise (AWGN) while mitigating the computational complexity of CS reconstruction algorithms. This research makes the following contributions. First, this research extends the signal model from single tones to multi-band signals with clustered support. Second, it shows that each stage in the R-FFAST front-end can be decomposed into individual nodes that form a fully distributed cooperative network. Lastly, this research empirically develops a constant false alarm rate (CFAR) detector that is used to identify the active frequency bins during the reconstruction process. The primary result of this research is showing that reliable spectrum detection is only possible when the average sampling rate of the cooperative network is greater than or equal to the sparsity of the spectrum. Simulation results are provided to demonstrate the effectiveness of the proposed framework and validate the findings of this research.
Temple University--Theses
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Poirier, Freddy. "Beam-diagnostic laser-wire study and fast luminosity spectrum measurement at the International Linear Collider." Thesis, Royal Holloway, University of London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421865.
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Willig, Judith A. (Judith Ann) 1953. "Paleo-archaic broad spectrum adaptations at the Pleistocene-Holocene boundary in Far Western North America." Thesis, University of Oregon, 1989. http://hdl.handle.net/1794/9220.
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xx, 463 p. : ill., maps. Two print copies of this title are available through the UO Libraries under the call number: KNIGHT E61 .W72 1989Western Clovis and Western Stemmed cultural traditions, archaeologically indexed by fluted (Clovis) and stemmed projectile point complexes, represent the earliest human occupation documented in Far Western North America. The temporal closeness of Western Clovis, dated roughly from 11,500 to 11,000 B.P., to Western Stemmed complexes known as early as 11,140 to 10,800 B.P., has generated debate over the age and historical relationship of these cultures. The frequent co-occurrence of fluted and stemmed points along the lowest strandlines in pluvial lake basins has also led scholars to hypothesize an early development of the characteristically "Archaic" lake-marsh adaptations known from later periods. Geoarchaeological research in the northern Alkali Lake Basin of south-central Oregon has addressed these issues of cultural chronology and economy by seeking data to test a paleoecological model of human land use in the basin from 11,500 to 7,000 B.P. The model posits a late Pleistocene Western Clovis settlement oriented to a small, shallow lake or pond, followed by an early Holocene Western Stemmed occupation around a much larger lake and marsh fringe. Data gathered through basin-wide site survey, stratigraphic studies, and high-resolution mapping of lake features and artifacts, support the model as proposed, and reveal a settlement pattern indicative of a "tethered" focus on local lake-marsh habitats. Research also verifies the horizontal separation of fluted and stemmed artifacts on different, sequent shorelines, indicating that Western Clovis occupation precedes Western Stemmed, although the two are close in time. Data from Alkali Basin, and elsewhere, support the notion that Far Western cultures developed broad-spectrum adaptations much earlier than was once thought. This implies that the foundations of the Western Archaic were already in place by 11,000 B.P. In keeping with the adaptive flexibility embodied within the Desert Culture concept, environmental data further suggest that this "paleo-Archaic" lifeway developed quickly, not gradually, in response to punctuated climatic change and the emerging mosaic of regional habitats which characterized the Pleistocene-Holocene boundary, at a time when the desert as we know it was just coming into being.
Adviser: Aikens, C. Melvin
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Grasso, Giacomo <1980>. "Neutronics analyses for fast spectrum nuclear systems and scenario studies for advanced nuclear fuel cycles." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2812/1/grasso_giacomo_tesi.pdf.
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The present PhD thesis summarizes the three-years study about the neutronic investigation of a new concept nuclear reactor aiming at the optimization and the sustainable management of nuclear fuel in a possible European scenario. A new generation nuclear reactor for the nuclear reinassance is indeed desired by the actual industrialized world, both for the solution of the energetic question arising from the continuously growing energy demand together with the corresponding reduction of oil availability, and the environment question for a sustainable energy source free from Long Lived Radioisotopes and therefore geological repositories.
Among the Generation IV candidate typologies, the Lead Fast Reactor concept has been pursued, being the one top rated in sustainability.
The European Lead-cooled SYstem (ELSY) has been at first investigated. The neutronic analysis of the ELSY core has been performed via deterministic analysis by means of the ERANOS code, in order to retrieve a stable configuration for the overall design of the reactor. Further analyses have been carried out by means of the Monte Carlo general purpose transport code MCNP, in order to check the former one and to define an exact model of the system.
An innovative system of absorbers has been conceptualized and designed for both the reactivity compensation and regulation of the core due to cycle swing, as well as for safety in order to guarantee the cold shutdown of the system in case of accident.
Aiming at the sustainability of nuclear energy, the steady-state nuclear equilibrium has been investigated and generalized into the definition of the ``extended'' equilibrium state. According to this, the Adiabatic Reactor Theory has been developed, together with a New Paradigm for Nuclear Power: in order to design a reactor that does not exchange with the environment anything valuable (thus the term ``adiabatic''), in the sense of both Plutonium and Minor Actinides, it is required indeed to revert the logical design scheme of nuclear cores, starting from the definition of the equilibrium composition of the fuel and submitting to the latter the whole core design.
The New Paradigm has been applied then to the core design of an Adiabatic Lead Fast Reactor complying with the ELSY overall system layout. A complete core characterization has been done in order to asses criticality and power flattening; a preliminary evaluation of the main safety parameters has been also done to verify the viability of the system.
Burn up calculations have been then performed in order to investigate the operating cycle for the Adiabatic Lead Fast Reactor; the fuel performances have been therefore extracted and inserted in a more general analysis for an European scenario. The present nuclear reactors fleet has been modeled and its evolution simulated by means of the COSI code in order to investigate the materials fluxes to be managed in the European region. Different plausible scenarios have been identified to forecast the evolution of the European nuclear energy production, including the one involving the introduction of Adiabatic Lead Fast Reactors, and compared to better analyze the advantages introduced by the adoption of new concept reactors.
At last, since both ELSY and the ALFR represent new concept systems based upon innovative solutions, the neutronic design of a demonstrator reactor has been carried out: such a system is intended to prove the viability of technology to be implemented in the First-of-a-Kind industrial power plant, with the aim at attesting the general strategy to use, to the largest extent. It was chosen then to base the DEMO design upon a compromise between demonstration of developed technology and testing of emerging technology in order to significantly subserve the purpose of reducing uncertainties about construction and licensing, both validating ELSY/ALFR main features and performances, and to qualify numerical codes and tools.
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Grasso, Giacomo <1980>. "Neutronics analyses for fast spectrum nuclear systems and scenario studies for advanced nuclear fuel cycles." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2812/.
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The present PhD thesis summarizes the three-years study about the neutronic investigation of a new concept nuclear reactor aiming at the optimization and the sustainable management of nuclear fuel in a possible European scenario. A new generation nuclear reactor for the nuclear reinassance is indeed desired by the actual industrialized world, both for the solution of the energetic question arising from the continuously growing energy demand together with the corresponding reduction of oil availability, and the environment question for a sustainable energy source free from Long Lived Radioisotopes and therefore geological repositories.
Among the Generation IV candidate typologies, the Lead Fast Reactor concept has been pursued, being the one top rated in sustainability.
The European Lead-cooled SYstem (ELSY) has been at first investigated. The neutronic analysis of the ELSY core has been performed via deterministic analysis by means of the ERANOS code, in order to retrieve a stable configuration for the overall design of the reactor. Further analyses have been carried out by means of the Monte Carlo general purpose transport code MCNP, in order to check the former one and to define an exact model of the system.
An innovative system of absorbers has been conceptualized and designed for both the reactivity compensation and regulation of the core due to cycle swing, as well as for safety in order to guarantee the cold shutdown of the system in case of accident.
Aiming at the sustainability of nuclear energy, the steady-state nuclear equilibrium has been investigated and generalized into the definition of the ``extended'' equilibrium state. According to this, the Adiabatic Reactor Theory has been developed, together with a New Paradigm for Nuclear Power: in order to design a reactor that does not exchange with the environment anything valuable (thus the term ``adiabatic''), in the sense of both Plutonium and Minor Actinides, it is required indeed to revert the logical design scheme of nuclear cores, starting from the definition of the equilibrium composition of the fuel and submitting to the latter the whole core design.
The New Paradigm has been applied then to the core design of an Adiabatic Lead Fast Reactor complying with the ELSY overall system layout. A complete core characterization has been done in order to asses criticality and power flattening; a preliminary evaluation of the main safety parameters has been also done to verify the viability of the system.
Burn up calculations have been then performed in order to investigate the operating cycle for the Adiabatic Lead Fast Reactor; the fuel performances have been therefore extracted and inserted in a more general analysis for an European scenario. The present nuclear reactors fleet has been modeled and its evolution simulated by means of the COSI code in order to investigate the materials fluxes to be managed in the European region. Different plausible scenarios have been identified to forecast the evolution of the European nuclear energy production, including the one involving the introduction of Adiabatic Lead Fast Reactors, and compared to better analyze the advantages introduced by the adoption of new concept reactors.
At last, since both ELSY and the ALFR represent new concept systems based upon innovative solutions, the neutronic design of a demonstrator reactor has been carried out: such a system is intended to prove the viability of technology to be implemented in the First-of-a-Kind industrial power plant, with the aim at attesting the general strategy to use, to the largest extent. It was chosen then to base the DEMO design upon a compromise between demonstration of developed technology and testing of emerging technology in order to significantly subserve the purpose of reducing uncertainties about construction and licensing, both validating ELSY/ALFR main features and performances, and to qualify numerical codes and tools.
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Lott, P. Aaron. "Fast solvers for models of fluid flow with spectral elements." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8743.
Full textAbstract:
Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Applied Mathematics & Statistics, and Scientific Computation Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Lee, Sung-Ik. "Far-infrared absorption of small metallic particles /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487261919113037.
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Leung, Cleo D. M. "Overtone Characterization of Garner Headjoints Using Spectrographic Analysis and Fast Fourier Transforms." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1396523100.
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Rynell, Anders. "An experimental and numerical study of an automotive cooling module." Doctoral thesis, KTH, Farkost och flyg, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-199285.
Full textAbstract:
Heavy vehicles are major emitters of noise. Especially at idle or low vehicle speeds a large portion of the noise emanates from the fan that forces the flow through the cooling module. The aim of this work is to investigate and reveal aerodynamic and acoustic installation effects linked to the cooling package. This introduces a multidisciplinary approach involving examination of the flow field, sound generation and sound propagation. The work includes two main parts: an experimental and a numerical part. The cooling module used throughout this work, named reduced cooling module, primarily includes a radiator, a shroud, a fan and a hydraulic engine to simplify the aeroacoustics analysis. The experimental part comprises measurements of the sound emanated from the cooling package. A new approach to the spectral decomposition method is developed yielding the fan sound power or spectrum to be formulated as a product of a source part and a system part scaling with the Strouhal number and the Helmholtz number. Also, a separate determination of the transmission loss of the radiator is performed. The impact of the radiator on the transmitted noise was found to be negligible. The numerical part incorporates comparisons from two aeroacoustics studies; a configuration where the fan is forced to operate at a fixed operation point and measured flow and turbulence statistics are available and the reduced cooling module. A hybrid turbulence modeling technique, IDDES, is adopted for the flow simulations. The sound propagation is calculated by the Ffowcs-Williams and Hawkings acoustic analogy when assuming a free-field sound propagation and by a finite element solver in the frequency domain to capture the installation effects. The simulated SPL conforms to the measured SPL and the blade response to the turbulent inflow and to the tip resolution, respectively, produce noise which spectral shape distribution is modified in accordance with earlier experimental findings published. Furthermore, the influence of an upstream radiator in close contact with the fan on the flow and sound fields is investigated. Here, the simulated aeroacoustic characteristics were found to change similarly to the acoustic measurements with and without radiator.
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Joel, Sandé. "Jodivi: An Application to Target Sound Sensitivity Features in People with Autism Spectrum Disorder." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36516.
Full textAbstract:
The main objective of this research work is to provide a tool to prevent the severe hearing sensitivity to patients with Autism Spectrum Disorder (ASD) experience. The key element in our work is to identify commonalities between sounds that bother an ASD patient, and implement a procedure using PC or smartphone as platform - based on those results, which will lead to the prevention of “bothersome” sounds for the ASD sufferer and later to desensitization. To do so, we implemented a first application that evaluates the auditory sound sensitivity of a person, and a second application that determines those factors that are related to hearing sensitivity of the patient, suggest sounds in the preventive process, and proposes use of appropriate sounds in the desensitization process.
While the current implementation is a prototype, we are determined to pursue the development at professional level and implemented as very user friendly application, which we hope will become a popular tool used by medical personnel and ASD patients for the identification of an individual’s specific sound sensitivities and his/her desensitization to those sounds.
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Martinazzo, Michele. "Cloud optical properties parameterizations for infrared high spectral resolution fast codes." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21747/.
Full textAbstract:
Lo scopo principale di questo lavoro di tesi è quello di produrre un set di parametrizzazioni analitiche per le proprietà ottiche delle nubi e degli aerosoli, utili per essere implementate in un codice veloce di trasferimento radiativo. Il codice veloce da noi preso in considerazione è sigma-IASI-as. Allo stato attuale, questo modello incorpora delle routines di Mie, le quali vengono sfruttate per il calcolo dello spessore ottico in presenza di nubi o aerosoli. Inoltre il codice sfrutta l'approssimazione di Chou allo scopo di tener conto dello scattering della radiazione infrarossa da parte delle particelle di nube o aerosol. La parametrizzazione prodotta potrà essere sfruttata allo scopo di creare un set di tabelle consultabili dal codice,
che potranno essere usate per sostituire le routine di Mie. Lo studio sugli effetti indotti dalla implementazione della approssimazione di Chou è stata investigata considerando diversi scenari atmosferici. Il modello sfruttato per calcolare le radianze è LBLDIS. Per ogni scenario sono quindi calcolate e confrontate le due soluzioni, implementando o non implementando l’approssimazione di Chou. Una parametrizzazione in funzione del raggio della distribuzione è trovata per: l’efficienza di estinzione, l’albedo si singolo scattering, il parametro di asimmetria, e il parametro di backscattering di Chou. L’impatto e le differenze nelle radianze introdotte dall'utilizzo dell’approssimazione di Chou e della parametrizzazione delle proprietà ottiche, è valutato per diversi scenari atmosferici.
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Fox, Cathryn. "Far-infrared spectral radiance studies : application to water vapour and cirrus." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/25752.
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This thesis presents the analysis of high-resolution spectral radiances recorded using the Imperial College Tropospheric Airborne Fourier Transform Spectrometer (TAFTS) instrument, which uniquely has the ability to record high resolution in-situ measurements, both up-welling and down-welling, in the far-infrared spectral region 80-800cm-1. The TAFTS data used in this work has been recorded during two diverse field campaigns, one ground-based, and one onboard the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft. The far-infrared spectral region has been shown to have a dominant contribution to the radiative cooling of the planet to space. Atmospheric water vapour is known to absorb radiation in a pure rotation band in the far-infrared, and also exhibits a background slowly-varying absorption known as the water vapour continuum. Observations of far-infrared radiances made by TAFTS during the Radiative Heating in Underexplored Bands Campaign (RHUBC) in Barrow, Alaska, are compared to simulations using line-by-line radiative transfer models in order to validate the current water vapour continuum parameterisation. Results presented here show that the current MT-CKD v2.5 parameterisation is accurately representing the water vapour continuum at wavenumbers between 350-500 cm-1. This thesis also considers the radiative effect of cirrus clouds in the far-infrared. These clouds have an important influence on current climate, and are known to scatter and absorb radiation in the infrared, however currently there have been relatively few measurements of the cirrus radiative effect in the far-infrared spectral region. Presented here are mid- and far-infrared observations of the radiative signature of cirrus recorded using the TAFTS and the UK Met Office Airborne Research Interferometer Evaluation System (ARIES) instruments, during the first phase of the aircraft-based Cirrus Coupled Cloud-Radiation Experiment (CIRCCREX), which flew out of Prestwick, Scotland in November 2013. These spectral measurements were compared to simulations using the LBLDIS model, which utilises cirrus scattering databases developed by Baum et al. at the SSEC, University of Wisconsin-Madison. This work represents the first time that the consistency of these databases have been tested across the entire infrared region. It was found that the model was underestimating brightness temperatures in the region 330-600 cm-1, and that further work is required in this region.
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Adamczyk, Aleksandra Katarzyna. "Analysis of the high-resolution ro-vibrational spectrum of DC3N in the far and mid infrared regions." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21732/.
Full textAbstract:
Cyanoacetylene HC3N is a molecule of great astronomical importance and it has been observed in many interstellar environments. Its deuterated form DC3N has been detected in number of sources from external galaxies to Galactic interstellar clouds, star-forming regions and planetary atmospheres. All these detections relied on previous laboratory investigations, which however still lack some essential information concerning its infrared spectrum. In this project, high-resolution ro-vibrational spectra of DC3N have been recorded in two energy regions: 150 – 450 cm-1 and 1800 – 2800 cm-1. In the first window the ν7← GS, 2ν7 ← ν7, ν5 ← ν7, ν5+ν7 ← 2ν7, ν6+ν7 → 2v7, 4ν7 ← 2ν7 bands have been assigned, while in the second region the three stretching fundamental bands ν1, ν2, ν3 have been observed and analysed. The 150 – 450 cm-1 region spectra have been recorded at the AILES beamline at the SOLEIL synchrotron (France), the 1800 – 2800 cm-1 spectra at the Department of Industrial Chemistry “Toso Montanari” in Bologna. In total, 2299 transitions have been assigned. Such experimental transition, together with data previously recorded for DC3N, were included in a least-squares fitting procedure from which several spectroscopic parameters have been determined with high precision and accuracy. They include rotational, vibrational and resonance constants. The spectroscopic data of DC3N have been included in a line catalog for this molecule in order to assist future astronomical observations and data interpretation. A paper which includes this research work has been published (M. Melosso, L. Bizzocchi, A. Adamczyk, E. Cane, P. Caselli, L. Colzid, L. Dorea, B. M. Giulianob, J.-C. Guillemine, M-A. Martin-Drumel, O. Piralif, A. Pietropolli Charmet , D. Prudenzano, V. M. Rivillad, F. Tamassia, Extensive ro-vibrational analysis of deuterated-cyanoacetylene (DC3N) from millimeter wavelengths to the infrared domain, Jour. of Quant. Spectr. and Rad. Tran. 254, 107221, 2020).
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Walsh, Jonathan A. (Jonathan Alan). "On-the-fly nuclear data processing methods for Monte Carlo simulations of intermediate and fast spectrum systems." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106700.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 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 203-212).
Computational methods for on-the-fly representation and processing of nuclear data within Monte Carlo neutron transport simulations of intermediate and fast spectrum systems are developed and implemented in a continuous-energy Monte Carlo code. First, a capability to compute temperature-dependent unresolved resonance region (URR) cross sections directly from zero-temperature average resonance parameters is presented. The use of this capability in benchmarking both evaluated and processed URR data is demonstrated. Results of this benchmarking lead to a partial resolution of a longstanding discrepancy between experiment and calculation results for a well-known fast critical assembly. Next, an on-the-fly probability table interpolation scheme for computing temperature-dependent URR cross sections is developed and used in analyses which show that interpolation on a relatively coarse temperature mesh (>100 K) can be used to reproduce results obtained with cross sections generated at an exact temperature. This enables the simulation of systems having detailed temperature distributions using probability table data which require significantly less memory than data generated on a fine temperature mesh. Additional methods for use in the investigation of two common approximations that are made in representing URR cross section data are developed. Namely, a multi-level URR cross section calculation capability is used to show that level-level interference effects in elastic scattering cross sections are negligible in many cases of interest. A capability to generate resonance structure in competitive reaction cross sections is used to show that neglecting cross section structure for reactions other than elastic scattering, capture, and fission can lead to non-negligible, unconservative biases (>100 pcm) in criticality safety calculations. The principal underlying assumption of the probability table method is also tested by comparing the results it yields with results that are averaged over many independent simulations, each using a single, independent realization of URR resonance parameters. Unknown URR resonance structure is observed to induce an uncertainty on the multiplication factor for intermediate and fast spectrum systems that is nearly an order of magnitude greater than that which is purely stochastic. This significantly increases the uncertainty to which results of simulations of those systems should be stated. Finally, a procedure for consistent, on-the-fly sampling of temperature-dependent neutron reaction kernels which requires no additional secondary distribution data is presented. It is used to show that Doppler effects may have only a small impact on elastic scattering secondary angular distributions at typical power reactor operating temperatures but can be appreciable at astrophysical temperatures.
by Jonathan A. Walsh.
Ph. D.
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Seth, Ernest L. "FASPEC, a program to determine group constants for up to 47 groups in a fast neutron spectrum." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45665.
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In reactor core design, a gap exists between the manual calculation of few-group constants and the many-group calculation, by large computer programs. A method is needed by which group constants may be calculated easily and quickly. The FASPEC program is designed to reduce the amount of manual calculation and to complement the large program by reducing the number of times the large program must be run to achieve desired results.
The program calculates group constants from 940 microgroups, collapsing to any user-specified number of macrogroups up to 47. FASPEC is based on group-averaged flux calculations by a solution of the Infinite medium neutron transport equation. Flux contributions from inelastic scatter are included while those from neutron upâ scatter are not. The energy spectrum considered is from 10 MeV to 0.625 eV. Required input is the atomic number density of each isotope, the number of macrogroups desired and the upper and lower microgroup numbers of each macrogroup. Input is facilitated by prompting in each case. Cross section look-up tables were provided by the Very Improved Monte Carlo code (VIM) for a mid-range Infinite hexagonal lattice. Self-shielding effects are included indirectly. A brief user's guide is provided.
Group constants calculated and stored for either terminal display or printed output are group number, lowest energy of the group, macroscopic removal cross section, macroscopic absorption cross section, diffusion coefficient, flux, macroscopic fission cross section, v, the average number of neutrons emitted per fission, and vΣf.
Master of Science
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Lindbo, Dag. "Spectral Accuracy in Fast Ewald Methods and Topics in Fluid Interface Simulation." Doctoral thesis, KTH, Numerisk analys, NA, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-48805.
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This work contains two separate but related parts: one on spectrally accurate and fast Ewald methods for electrostatics and viscous flow, and one on micro- and complex fluid interface problems. In Part I we are concerned with fast and spectrally accurate methods to compute sums of slowly decaying potentials over periodic lattices. We consider two PDEs: Laplace (electrostatics, the Coulomb potential) and Stokes (viscous flow, the ``Stokeslet'' potential). Moreover, we consider both full and planar periodicity, the latter meaning that periodicity applies in two dimensions and the third is ``free''. These are major simulation tasks in current molecular dynamics simulations and in many areas of computational fluid mechanics involving e.g. particle suspensions. For each of the four combinations of PDE and periodic structure, we give spectrally accurate and O(N log N) fast methods based on Ewald's or Ewald-like decompositions of the underlying potential sums. In the plane-periodic cases we derive the decompositions in a manner that lets us develop fast methods. Associated error estimates are developed as needed throughout. All four methods can be placed in the P3M/PME (Particle Mesh Ewald) family. We argue that they have certain novel and attractive features: first, they are spectral accurate; secondly, they use the minimal amount of memory possible within the PME family; third, each has a clear and reliable view of numerical errors, such that parameters can be chosen wisely. Analytical and numerical results are given to support these propositions. We benchmark accuracy and performance versus an established (S)PME method. Part II deals with free boundary problems, specifically numerical methods for multiphase flow. We give an interface tracking method based on a domain-decomposition idea that lets us split the interface into overlapping patches. Each patch is discretized on a uniform grid, and accurate and efficient numerical methods are given for the equations that govern interface transport. We demonstrate that the method is accurate and how it's used in immersed boundary, and interface, Navier-Stokes methods, as well as in a boundary integral Stokes setting. Finally, we consider a problem in complex fluidics where there is a concentration of surfactants \emph{on} the interface and the interface itself is in contact with a solid boundary (the contact line problem). We argue that the domain-decomposition framework is attractive for formulating and treating complex models (e.g. involving PDEs on a dynamic interface) and proceed with developing various aspects of such a method.QC 20111125
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Skipper, Chris. "Fast spectral variability in the X-ray emission of accreting black holes." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/360394/.
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The X-ray emission from accreting black holes provides the perfect probe for testing the geometry, behaviour and conditions present in the innermost regions of the accretion flow. In this thesis I use X-ray spectral analysis to investigate the properties of accreting black holes that extend over several orders of magnitude in accretion rate (m˙ E) and black hole mass (MBH), from the stellar mass black holes in X-ray binary systems (XRBs)to the supermassive black holes in active galactic nuclei(AGN). Firstly, through a survey of X-ray emission in the nuclei of nearby galaxies I show that the usefulness of the X-ray to optical line ratios as a Compton-thick diagnostic does not extend to low luminosity AGN, and instead these ratios may have more practical use in distinguishing between AGN and non-AGN emission processes. Secondly, and more importantly, the main focus of this thesis is upon the variability of the Comptonised power-law X-ray spectral component, and more specifically an examination of how the photon index
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Cossich, Marcial de Farias William <1987>. "Analysis of far-infrared (FIR) high spectral resolution data for cloud studies." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9487/1/Tesi_WilliamCossich.pdf.
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The Far-Infrared Outgoing Radiation Understanding and Monitoring (FORUM) mission has recently been selected by the European Satellite Agency (ESA) as 9 th Earth Explorer mission. FORUM mission aims at studying the water vapor and clouds by filling the long-standing gap in Far-Infrared (FIR) spectral observations from space. In the framework of the FORUM mission, this thesis analyses FIR measurements to characterize the spectral signatures of radiance in presence of ice clouds. At this purpose, a cloud identification and classification code (named CIC) is implemented. CIC is an innovative machine learning algorithm, based on principal component analysis, able to perform cloud detection and scene multi-class classification. CIC is easily adaptable to different datasets and type of spectral sensors. It is firstly tested against a synthetic dataset comprising simulated measurements of the FORUM mission. Subsequently, CIC is applied to airborne interferometric data and finally it is used for the analysis of measured downwelling radiances collected in very dry conditions on the Antarctic Plateau. Provided the excellent performances of the algorithm, especially in the identification of thin cirrus clouds, CIC is adopted as the classificator in the official ESA FORUM End-to-End simulator (FE2ES). The FE2ES is a complex chain of codes used to simulate the entire FORUM mission from satellite orbit and geometry to level 2 product analysis. An extensive use of CIC is performed on ground-based radiances collected in Antarctica. The dataset is exploited to test and to optimize the CIC algorithm and for the developing of punctual statistic of cloud occurrence in the Antarctic Plateau. Meteorological conditions from this region are also analysed and correlated with the presence of clouds. The studies presented in this work showed the potentiality and the importance of the exploitation of spectral radiance measurements in the FIR for cloud identification and classification.
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Bekker, Scott Henry. "Continuous real-time recovery of optical spectral features distorted by fast-chirped readout." Thesis, Montana State University, 2006. http://etd.lib.montana.edu/etd/2006/bekker/BekkerS0506.pdf.
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Crumrine, Daiquirie. "Eye-gaze profiles of children with autism spectrum disorders in relation to fast-mapping and visual search abilities." Diss., Wichita State University, 2012. http://hdl.handle.net/10057/6095.
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Children learn new words through a process termed fast-mapping, which involves pairing novel words and objects after minimal exposure (Carey & Bartlett, 1978). There have been studies conducted to understand the fast-mapping processes in children with typical development (TD); however, this phenomenon has received less attention for children with autism spectrum disorders (ASD). In addition, no studies were found that investigated the eye-gaze patterns and fast-mapping abilities of children with ASD and TD. Furthermore, research involving visual search tasks has suggested that children with ASD demonstrate superior visual search skills when compared to children with TD (O’Riordan, Plaisted, Driver, & Baron-Cohen, 2001). The purpose of this study was two-fold: (1) to compare the eye-gaze patterns of children with ASD and TD in relation to fast-mapping; and (2) to compare the visual search abilities of children with ASD and TD. Ten children diagnosed with ASD and twenty children with TD, ages 5-7 participated. Participants were matched on nonverbal intelligence and receptive vocabulary skills. The Tobii 1750 eye-tracking system was used to capture eye-tracking measures. Overall, the results of Study 1 revealed that children with ASD were able to fast-map novel images and text at a similar rate to children with TD, despite having fewer fixations and shorter total fixation duration on novel stimuli. Study 2 revealed that children with ASD had similar visual search patterns as compared to children with TD. Children with ASD demonstrated more errors when locating targets but exhibited similar reaction times compared to children with TD. In summary, it appears that for the participants in these studies, children with ASD had different eye-gaze patterns for fast-mapping tasks and similar visual search skills when compared to TD children.Thesis (Ph.D.)--Wichita State University, College of Health Professions, Dept. of Communication Sciences and Disorders
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Scott, Ashley Anna. "Imaging genetics of frontostriatal function in autism spectrum disorders." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1872142711&sid=8&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Van, Wyk BJ, Wyk MA Van, and den Bergh F. Van. "A note on difference spectra for fast extraction of global image information." SAIEE Africa Research Journal, 2007. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001081.
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The concept of an Image Difference Spectrum, a novel tool for the extraction of global
image information, is introduced. It is shown that Image Difference Spectra are fast alternatives to
granulometric curves, also referred to as pattern spectra. Image Difference Spectra are
computationally easy to implement and are suitable for real-time applications.
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Juanola-Parramon, R. "A far-infrared spectro-spatial space interferometer : instrument simulator and testbed implementation." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1427371/.
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FIRI (Far Infrared Interferometer) is a concept for a spatial and spectral space interferometer with an operating wavelength range 25-300 μm and sub-arcsecond angular resolution, and is based on the combination of two well-known techniques, Stellar Interferometry and Fourier Transform Spectroscopy, to achieve high spectral and spatial resolution in the Far Infrared (Chapter 2). The resulting technique is called Double Fourier Spatio-Spectral Interferometry (Mariotti and Ridgway 1988). With increased spatial and spectral resolution a number of interesting science cases such as the formation and evolution of AGN and the characterization of gas, ice and dust in disks undergoing planetary formation, among others, can be investigated. In this thesis I present two approaches to study the feasibility of a FIRI system a) An experimental approach via the Cardiff University-UCL FIRI Testbed (Chapter 3), a laboratory prototype spectral-spatial interferometer to demonstrate the feasibility of the Double-Fourier technique at the Far-infrared regime, including the Wide-Filed Imaging Interferometry Testbed at the Optical and Near-infrared regime. b) The Far-Infrared Interferometer Instrument Simulator (FIInS) to assess the performance of a space-based system (Chapter 4). The main goal of this software is to simulate both the input and the output of such a system. With FIInS, once a set of modeled scientific data is available, one can compare an input sky map with the synthesized one after data reduction and processing algorithms have been applied. To validate FIInS data from the Cardiff University-UCL FIRI testbed has been used (Chapter 5). FIInS is intended to be a tool for the astronomical community to explore the limits of a space interferometer. For this reason it is also applied to simulated scientific data (Chapter 6), more specifically to simulated circumstellar disks to test the simulator in a more realistic scenario.
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O'Rourke, Douglas James Peter. "Spectral modeling of dusty galaxies, and evolution of the far infrared-radio correlation." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610847.
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CARESTIA, MARIACHIARA. "Spectral analysis of biological agents to implement a tool for fast biological detection." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2014. http://hdl.handle.net/2108/202303.
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Biosecurity and biosafety are key concerns of modern society. A plethora of biological agents (BAs) like toxins, bacteria, viruses, fungi and parasites, are able to cause damage to humans, animals and plants, and some of them can even be used as non-conventional weapons. Indeed, the use of BAs for military or terroristic purposes has been recorded from the ancient Roman Empire until present days and, today, it is considered one of the four main threat of the CBRN (Chemical, Biological, Radiological, Nuclear) group. One of the most remarkable characteristics of BAs is that they are able to spread unnoticed among the population for days or weeks before the first symptoms of the disease the cause become evident. Moreover, BAs are almost colorless and odorless and their sizes (that ranges from few nanometers for protein toxins to tens of micrometers for bacteria) makes them hardly noticeable to the human eye.
Finally, different BAs may cause similar symptoms but require different treatments, so it is paramount to gain the capability to detect and characterize BAs at the early stage of their diffusion.
Although the ultimate goal would be the development of a quick, field portable, user friendly tool for the unambiguous identification of BAs, together with the possibility to perform stand-off detection to reduce risks for operators and population, to date, no single technique has proved to achieve these results leading to a constant search for a compromise between rapidity, specificity, and stand-off capabilities. In this framework, UV-Light Induced Fluorescence (UV-LIF) is considered one of the most promising techniques to perform detection from medium to long distances (to date, from hundreds of meters to few kilometers), although photoluminescence from BAs is very weak and day time measurements may represent a real challenge; moreover, background aerosol UV signals poses further issues that are still to be soundly addressed.
The PhD research activity consisted of a preliminary analysis (of the characteristics) of a system for the quick classification of BAs released in the atmosphere through the use of
PhD in Industrial Engineering - Final Dissertation – Mariachiara Carestia
SPECTRAL ANALYSIS OF BIOLOGICAL AGENTS TO IMPLEMENT A TOOL FOR FAST
BIOLOGICAL DETECTION
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UV-LIF techniques, to perform detection to warn and treat. In particular, this thesis reports on new insights on the standardization of the methodology to build and test a training database of BAs signatures, the multispectral analysis of BAs optical signatures, the constitution of a multispectral database, and the statistical and mathematical tools for the automatic classification of the spectral signatures. Moreover, quantum efficiency tests have been performed on biological samples to acquire information useful for the definition of the structural features of a tool for BAs detection.
Measurements of different classes of BAs (toxins, vegetative bacteria and bacterial spores), some of them simulants of Biological Warfare Agents (BWAs), have been performed by conveniently selecting six excitation wavelengths in the UV spectral range (namely, 266, 273, 280, 300, 340 and 355 nm). The spectral signatures have been analyzed and different solutions for their automatic classification have been proposed and compared. In particular, Support Vector Regression based methods have been applied and an algorithm has been proposed with the aim of analyzing a restricted database of BAs.
This work provides valuable information both for setting the basis for the set-up of a laboratory demonstrator that will be the first step toward the implementation of a tool for quick biological detection able to be installed on an Unmanned Air Vehicle (UAV), and for selecting the criteria for the implementation and analysis of a BAs spectral signatures’ database.
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Sivijs, Andrew K. "The resort development spectrum (RDS) : case study application of the RDS for Cairns, Far North Queensland and Bali, Indonesia /." [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18578.pdf.
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Williams, Amie M. "Language development in preschool children with autism spectrum disorders investigating fast-mapping abilities and utilization of word learning constraints /." Thesis, [Tuscaloosa, Ala. : University of Alabama Libraries], 2009. http://purl.lib.ua.edu/52.
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Jolma, Kalevi. "High resolution far infrared spectra of certain light linear three and four atomic molecules." Oulu : University of Oulu, 1985. http://catalog.hathitrust.org/api/volumes/oclc/15465428.html.
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Wolf, Michael Christopher. "A novel broad-spectrum antiviral targeting entry of enveloped viruses." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1971758861&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Lepage, Pierre. "Etude structurale de proteines lipophiles (proteolipides) du systeme nerveux central : utilisation de la spectrometrie de masse pour le sequencage de peptides." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13007.
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Eriksson, Jacob. "Calculations of neutron energy spectra from fast ion reactions in tokamak fusion plasmas." Thesis, Uppsala University, Applied Nuclear Physics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-120425.
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A MATLAB code for calculating neutron energy spectra from JET discharges was developed. The code uses the fuel ion distribution calculated by the computer code SELFO to generate the spectrum through a Monte-Carlo simulation. The calculated spectra were then compared against experimental results from the neutron spectrometer TOFOR. In the calculations, the exact orbits of the fuel ions are taken into account, in order to investigate what effects this has on the spectrum. The reason for this is that, for certain plasma heating scenarios, large populations of fast fuel ions are formed. These fast ions may have Larmor radii of the order of decimeters, which is comparable to the width of the sight line of TOFOR, and may therefore affect the recorded neutron spectrum. A JET discharge with both NBI and 3rd harmonic ICRF heating was analyzed. The results show that the details of the line of sight of the detector indeed affects the neutron spectrum. This effect is probably important for other diagnostics techniques, such as gamma-ray spectroscopy and neutral particle analysis, as well. Good agreement with TOFOR data is observed, but not for the exact same time slice of the discharge, which leaves some questions yet to be investigated.
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Klenow, Bradley. "Finite and Spectral Element Methods for Modeling Far-Field Underwater Explosion Effects on Ships." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/37648.
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The far-field underwater explosion (UNDEX) problem is a complicated problem dominated by two phenomena: the shock wave traveling through the fluid and the cavitation in the fluid. Both of these phenomena have a significant effect on the loading of ship structures subjected to UNDEX.
An approach to numerically modeling these effects in the fluid and coupling to a structural model is using cavitating acoustic finite elements (CAFE) and more recently cavitating acoustic spectral elements (CASE). The use of spectral elements in CASE has shown to offer the greater accuracy and reduced computational expense when compared to traditional finite elements. However, spectral elements also increase spurious oscillations in both the fluid and structural response.
This dissertation investigates the application of CAFE, CASE, and a possible improvement to CAFE in the form of a finite element flux-corrected transport algorithm, to the far-field UNDEX problem by solving a set of simplified UNDEX problems. Specifically we examine the effect of increased oscillations on structural response and the effect of errors in cavitation capture on the structural response which have not been thoroughly explored in previous work.
The main contributions of this work are a demonstration of the problem dependency of increased oscillations in the structural response when applying the CASE methodology, the demonstration of how the sensitivity of errors in the structural response changes with changes in the structural model, a detailed explanation of how error in cavitation capture influences the structural response, and a demonstration of the need to accurately capture the shape and magnitude of cavitation regions in the fluid in order to obtain accurate structural response results.Ph. D.