Rozprawy doktorskie na temat „Phase spectrum”
Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Phase spectrum.
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Phase spectrum”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
1
Stark, Anthony. "Phase Spectrum Based Speech Processing and Spectral Energy Estimation for Robust Speech Recognition". Thesis, Griffith University, 2011. http://hdl.handle.net/10072/366490.
Pełny tekst źródłaStreszczenie:
Speech is the dominant mode of communication between humans; simple to learn, easy to use and integral for modern life. Given the importance of speech, development of a human-machine speech interface has been greatly anticipated. This challenging task is encapsulated in the digital speech processing research field. In this dissertation, two specific areas of research are considered: 1) the use of short-time Fourier spectral phase in digital speech processing and 2) use of the minimum mean square error spectral energy estimator for environment-robust automatic speech recognition. In speech processing and modelling, the short-time Fourier spectral phase has been considered of minor importance. This is because classic psychoacoustic experiments have shown speech intelligibility to be closely related to short-time Fourier spectral magnitude. Given this result, it is unsurprising that the majority of speech processing literature has involved exploitation of the short-time magnitude spectrum. Despite this, recent studies have shown useful information can be extracted from the spectral phase of speech. As a result, it is now known that spectral phase possesses much of the same intelligibility information as spectral magnitude. It is this avenue of research that is explored in greater detail within this dissertation. In particular, we investigate two phase derived quantities – the short-time instantaneous frequency spectrum and the short-time group delay spectrum. The properties of both spectra are investigated mathematically and empirically, identifying the relationship between known speech features and the underlying phase spectrum. We continue the investigation by examining two related quantities – the instantaneous frequency deviation and the group delay deviation. As a result of this research, two novel phase-based spectral representations are proposed, both of which show a high degree information applicable to speech processing.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text
2
Cesbron, Fred́eŕique Chantal. "Pitch detection using the short-term phase spectrum". Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/15503.
Pełny tekst źródła
3
Fletcher, Michael John. "Enhanced Implementations for Arbitrary-Phase Spread Spectrum Waveforms". Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/90286.
Pełny tekst źródłaStreszczenie:
The use of practically non-repeating spreading codes to generate sequence-based spread spectrum waveforms is a strong method to improve transmission security, by limiting an observers opportunity to cross-correlate snapshots of the signal into a coherent gain. Such time-varying codes, particularly when used to define multi-bit resolution arbitrary-phase waveforms, also present significant challenges to the intended receiver, which must synchronize correlator processing to match the code every time it changes. High-order phase shift keying (PSK) spread modulations do, however, provide an overall whiter spectral response than legacy direct sequence spread spectrum (DSSS) signals. Further, the unique ability to color the output signal spectrum offers new advantages to optimize transmission in a non-white frequency channel and to mitigate observed interference. In high data rate applications, the opportunity to inject a time-aligned co-channel underlay-based watermark for authentication at the receiver is an effective method to enhance physical layer (PHY) security for virtually any primary network waveform. This thesis presents a series of options to enhance the implementation of arbitrary-phase chaotic sequence-based spread spectrum waveforms, including techniques to significantly reduce fallthrough correlator hardware resources in low-power sensing devices for only minor performance loss, capabilities for programming chosen frequency domain spectra into the resulting spread spectrum signal, and design considerations for underlay watermark-based PHY-layer firewalls. A number of hardware validated prototypes were built on an Intel Arria 10 SoC FPGA to provide measurable results, achieving substantial computational resource gains and implementation flexibility.Master of Science
This thesis presents a series of options for enhancing the implementation of arbitrary-phase spread spectrum waveforms, a highly-secure class of wireless technologies, in order to reduce design complexity with minimal loss, provide methods for real-time performance adaptations, and extend the traditional application space for increased security of communications in other networks. A number of enhanced hardware prototypes were implemented to provide measurable results, achieving substantial computational resource gains and design flexibility. Given the computational resources and power constraints of devices in the Internet of Things (IoT), the signal detection loss of 2.10 dB for reducing the hardware logic utilization of the brute force fallthrough correlator by more than 76% (and eliminating the need to dedicate computationally-expensive embedded multipliers) is a very reasonable trade. While the waveform is fundamentally designed for increased security, adapting to widespread and/or commercial use may allow some sacrifice of the signal’s ability to avoid interception/detection to improve performance in undesirable operating conditions. In a similar, yet reversed, case, injecting a watermarking signature at the physical layer (PHY) of less-secure wireless technologies for receiver-side authentication also proves to be beneficial.
4
Alsteris, Leigh, i n/a. "Short-Time Phase Spectrum in Human and Automatic Speech Recognition". Griffith University. School of Microelectronic Engineering, 2006. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20060727.090845.
Pełny tekst źródłaStreszczenie:
Incorporating information from the short-time phase spectrum into a feature set for automatic speech recognition (ASR) may possibly serve to improve recognition accuracy. Currently, however, it is common practice to discard this information in favour of features that are derived purely from the short-time magnitude spectrum. There are two reasons for this: 1) the results of some well-known human listening experiments have indicated that the short-time phase spectrum conveys a negligible amount of intelligibility at the small window durations of 20-40 ms used for ASR spectral analysis, and 2) using the short-time phase spectrum directly for ASR has proven di?cult from a signal processing viewpoint, due to phase-wrapping and other problems. In this thesis, we explore the possibility of using short-time phase spectrum information for ASR by considering the two points mentioned above. To address the ?rst point, we conduct our own set of human listening experiments. Contrary to previous studies, our results indicate that the short-time phase spectrum can indeed contribute signi?cantly to speech intelligibility over small window durations of 20-40 ms. Also, the results of these listening experiments, in addition to some ASR experiments, indicate that at least part of this intelligibility may be supplementary to that provided by the short-time magnitude spectrum. To address the second point (i.e., the signal processing di?culties), it may be necessary to transform the short-time phase spectrum into a more physically meaningful representation from which useful features could possibly be extracted. Speci?cally, we investigate the frequency-derivative (or group delay function, GDF) and the time-derivative (or instantaneous frequency distribution, IFD) as potential candidates for this intermediate representation. We have performed various experiments which show that the GDF and IFD may be useful for ASR. We conduct several ASR experiments to test a feature set derived from the GDF. We ?nd that, in most cases, these features perform worse than the standard MFCC features. Therefore, we suggest that a short-time phase spectrum feature set may ultimately be derived from a concatenation of information from both the GDF and IFD representations. For best performance, the feature set may also need to be concatenated with short-time magnitude spectrum information. Further to addressing the two aforementioned points, we also discuss a number of other speech applications in which the short-time phase spectrum has proven to be very useful. We believe that an appreciation for how the short-time phase spectrum has been used for other tasks, in addition to the results of our research, will provoke fellow researchers to also investigate its potential for use in ASR.
5
高樹豐 i Shu-fung Ko. "Emission morphologies and phase-resolved spectrum of gamma ray pulsar". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31224489.
Pełny tekst źródła
6
Ko, Shu-fung. "Emission morphologies and phase-resolved spectrum of gamma ray pulsar /". Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk:8888/cgi-bin/hkuto%5Ftoc%5Fpdf?B23476370.
Pełny tekst źródła
7
Alsteris, Leigh. "Short-Time Phase Spectrum in Human and Automatic Speech Recognition". Thesis, Griffith University, 2006. http://hdl.handle.net/10072/366602.
Pełny tekst źródłaStreszczenie:
Incorporating information from the short-time phase spectrum into a feature set for automatic speech recognition (ASR) may possibly serve to improve recognition accuracy. Currently, however, it is common practice to discard this information in favour of features that are derived purely from the short-time magnitude spectrum. There are two reasons for this: 1) the results of some well-known human listening experiments have indicated that the short-time phase spectrum conveys a negligible amount of intelligibility at the small window durations of 20-40 ms used for ASR spectral analysis, and 2) using the short-time phase spectrum directly for ASR has proven di?cult from a signal processing viewpoint, due to phase-wrapping and other problems. In this thesis, we explore the possibility of using short-time phase spectrum information for ASR by considering the two points mentioned above. To address the ?rst point, we conduct our own set of human listening experiments. Contrary to previous studies, our results indicate that the short-time phase spectrum can indeed contribute signi?cantly to speech intelligibility over small window durations of 20-40 ms. Also, the results of these listening experiments, in addition to some ASR experiments, indicate that at least part of this intelligibility may be supplementary to that provided by the short-time magnitude spectrum. To address the second point (i.e., the signal processing di?culties), it may be necessary to transform the short-time phase spectrum into a more physically meaningful representation from which useful features could possibly be extracted. Speci?cally, we investigate the frequency-derivative (or group delay function, GDF) and the time-derivative (or instantaneous frequency distribution, IFD) as potential candidates for this intermediate representation. We have performed various experiments which show that the GDF and IFD may be useful for ASR. We conduct several ASR experiments to test a feature set derived from the GDF. We ?nd that, in most cases, these features perform worse than the standard MFCC features. Therefore, we suggest that a short-time phase spectrum feature set may ultimately be derived from a concatenation of information from both the GDF and IFD representations. For best performance, the feature set may also need to be concatenated with short-time magnitude spectrum information. Further to addressing the two aforementioned points, we also discuss a number of other speech applications in which the short-time phase spectrum has proven to be very useful. We believe that an appreciation for how the short-time phase spectrum has been used for other tasks, in addition to the results of our research, will provoke fellow researchers to also investigate its potential for use in ASR.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Microelectronic Engineering
Full Text
8
Wojcicki, Kamil Krzysztof. "Role of the Short-Time Phase Spectrum in Speech Processing". Thesis, Griffith University, 2011. http://hdl.handle.net/10072/366376.
Pełny tekst źródłaStreszczenie:
Majority of speech processing algorithms that employ the short-time Fourier transform process the short-time magnitude spectrum, while either discarding the short-time phase spectrum or leaving it unchanged. This is in-part due to a long-standing belief among speech researchers that the short-time phase spectrum, computed over small analysis window durations of 20–40 ms, contains little useful information and is thus (mostly) unimportant for speech processing (though it is accepted that the phase spectrum does contribute to some extent to naturalness and quality aspects of speech). The above belief has been supported by numerous studies presented in the literature. Results of recent speech perception experiments suggest, however, that the phase spectrum (at small analysis window durations of 20–40 ms) does contain significant amount of useful information, provided that the analysis window function is carefully selected. It was reported that the use of non-tapered analysis windows functions (such as the rectangular window) significantly improves intelligibility of the phase spectrum. This improvement was attributed to the spectral characteristics of the non-tapered analysis windows and—in particular—to their low spectral dynamic range. The main aim of the research presented in this dissertation is to further examine the importance of the short-time phase spectrum for human speech perception. It is hoped that results of such an examination can provide an incentive for further research in this direction. Three studies that investigate the usefulness of the phase spectrum for human speech perception are presented in this thesis. These studies employ human listening tests to explore the importance of the phase spectrum for speech intelligibility, speaker dependent speech information and speech quality. In each of these studies the effect of the spectral dynamic range of an analysis window function is systematically examined.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text
9
Thayaparan, Subramaniam. "Delay-locked loop techniques in direct sequence spread-spectrum receivers". Thesis, Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21904108.
Pełny tekst źródła
10
Tran, Ky-Anh. "A spread-spectrum clock generator using phase interpolation for EMI reduction". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91700.
Pełny tekst źródłaStreszczenie:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.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 123-125).
The spurious-free dynamic range of RF DAC's are limited by the heavy digital do- main switching, which interferes with the analog output signal. A design, layout and simulation of a spread-spectrum clock generator (SSCG) is presented. The SSCG modulates the clock frequency used to switch the digital blocks of the DAC in order to reduce electromagnetic interference (EMI) spurs at the analog output signal of the DAC. Leveraging on a phase control architecture rather than a traditional PLL, the SSCG system is shown to reduce the spectral height a divided down clock spur up to 19.6dB. The SSCG is designed in TSMC's 65nm CMOS process. It takes in quadrature, differential clocks at either 2.5GHz or 5GHz, and provides quadrature output clocks at 625MHz or 1.25GHz. The output spectrum of the clock can be attenuated up to 19.6dB relative to the spectrum of an unspread clock. The core of the SSCG is a phase interpolator, which takes in quadrature input clocks and interpolates between them to move the frequency around. To help process the signals before and after interpolation, the SSCG incorporates input variable gain lters, output restoration buffers and divide by 4 circuits. Extensive transistor and behavioral simulations are used to verify the design.
by Ky-Anh Tran.
M. Eng.
11
Radi, Haidar M. "Frequency hopping spread spectrum multiplexing for interferometric optical fibre sensor networks". Thesis, Manchester Metropolitan University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387483.
Pełny tekst źródła
12
Xie, Zhaohua, i 謝照華. "The study of phase-resolved spectra of gamma-ray pulsars". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B26665633.
Pełny tekst źródła
13
Inberg, R. Brandon. "Enhanced step mode FTIR position control". Thesis, Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/inberg/InbergR1205.pdf.
Pełny tekst źródła
14
Zhao, Xianming, Mingji Yang, Tingxian Zhou i Liqun Meng. "SPREAD SPECTRUM COMMUNICATION SCHEME USING PHASESHIFTING SEQUENCE AND ITS PROPERTIES". International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/609223.
Pełny tekst źródłaStreszczenie:
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, CaliforniaThis paper analyzes the pseudo-random characteristic of m-sequence and proposes a spread spectrum communication scheme in which the phase-shifting sequences of msequence can be used as the spread spectrum code under given condition. Therefore, the available spread spectrum code set is expanded. It is theoretically proved that there are some advantages in using phase-shifting sequences instead of the conventional msequences or GOLD-sequences in spread spectrum communication system.
15
Leung, Chiu Hon. "The output frequency spectrum of a thyristor phase-controlled cycloconverter using digital control techniques". Thesis, University of Plymouth, 1985. http://hdl.handle.net/10026.1/2261.
Pełny tekst źródłaStreszczenie:
The principle of operation dictates that the output of a cycloconverter contains some harmonics. For drive applications, the harmonics at best increase losses in the motor and may well cause instability. Various methods of analysing the output waveform have been considered. A Fortran 77 program employing a modified Fourier series, making use of the fact that the input waveforms are sinusoidal, was used to compute the individual harmonic amplitudes. A six pulse three phase to single phase cycloconverter was built and a Z-80 microprocessor was used for the control of firing angles. Phase locked loops were used for timing, and their effect upon the output with changing input frequency and voltage were established. The experimental waveforms are analysed by a FFT spectrum analyser. The flexibility of the control circuit enables the following investigations not easily carry out using traditional analog control circuit. The phase relationship between the cosine timing and reference wave in the cosinusoidal control method was shown to affect the output waveform and hence the harmonic content. There is no clear optimum value of phase and the T.H.D. up to 500Hz remains virtually constant. However, the changes of individual harmonic amplitudes is quite significant. In practice it may not be possible to keep the value of phase constant but it should be considered when comparing control strategies. Another investigation involves the changing of the last firing angle in a half cycle. It shows that the value of firing angles produced by the cosinusoidal control method is desirable. Operation at theoretical maximum output frequency was also demonstrated.
16
du, Plessis Laura. "Using emotional intelligence to support learners with Autism Spectrum Disorder in the Foundation Phase". Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/60939.
Pełny tekst źródłaStreszczenie:
The purpose of this study was to identify characteristics pertaining to emotional intelligence (EI) that parents and Foundation Phase teachers may use when supporting learners with autism spectrum disorder (ASD) in an inclusive classroom setting. Teachers are facing various degrees of challenges due to the demands of a range of diverse needs attributable to the influx of learners with disabilities in the school system. Given the increase in the number of children diagnosed with ASD, research indicates that it is likely that teachers will encounter learners with ASD in their classes. Teachers are generally not trained to identify and cope with such a disability, as many requirements of these learners are beyond the services of a general school system. A multiple case study was conducted where the perspectives of a teacher and two parents were gained, in order to understand experiences with children with ASD from the participants' point of view. The primary aim of this study was therefore to provide both parents and teachers with listed characteristics of EI that they could utilise while supporting learners with ASD in households or the educational sphere.
Findings illuminated the collective characteristics of learners with ASD, which include intense obsessions with a narrow range of subjects, repetitive routines, central coherence difficulties and problems with social-emotional functioning, communication and executive functioning. These indicators require specific responses from parents and teachers to effectively provide support to these learners. Qualities identified that relate to EI are patience, empathy, problem solving skills, working collaboratively with parents and being proactive. The main recommendation relates to specific training in EI skills, to prepare student teachers in supporting the growing number of learners with ASD in their classes.Dissertation (MEd)--University of Pretoria, 2017.
Early Childhood Education
MEd
Unrestricted
17
Handsel, Jennifer. "Anisotropy and spin relaxation in the condensed phase". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:8a268360-4e6c-4a18-96e2-f60a57b5b5df.
Pełny tekst źródłaStreszczenie:
Chapter 1 introduces the concept of spin, how spins interact, and how the spin state in a radical pair can affect the outcome of a chemical reaction between the unpaired electrons. The computational methodology for simulating such radical pairs is also discussed. Chapter 2 discusses anisotropy in the singlet recombination yield of a radical pair in a carotenoid-porphyrin-fullerene triad, containing many hyperfine couplings. The singlet yield was calculated as a function of the direction of an applied magnetic field, using symmetry in the molecule to reduce the size of the problem. The symmetry reduction was partially successful, however it was not possible to include all the hyperfine couplings in the molecule. Chapter 3 introduces a radical pair located on a flavin ligand and a tryptophan residue in the protein cryptochrome, and discusses the spin-relaxation mechanism of singlet-triplet dephasing. Magnetic field effect curves, describing the formation of a secondary radical pair as a function of applied magnetic field, were found to be broader in longer-lived radical pairs, due to dephasing caused by spin-selective recombination to the singlet ground state. Additional singlet-triplet dephasing may occur due to hopping of one of the unpaired electrons, between a zone of strong exchange interaction and a zone of negligible exchange interaction, although this is an incomplete description of the spin-relaxation. Chapter 4 discusses the effect of rotational tumbling on spin-relaxation in the flavin-tryptophan radical pair in cryptochrome. Simulations indicated that the resulting modulation of anisotropic hyperfine couplings contributed modestly to spinrelaxation during transient absorption measurements, but was insufficient to explain the lack of an experimental low-field effect, or to explain the width of the experimental magnetic field effect curves as a function of magnetic field strength. Chapter 5 discusses magnetic field effects on the mutual annihilation of a pair of triplet excitons in tetracene and anthracene crystals. The experimental singlet recombination yield was found, for the first time, to be modulated as a function of the direction of a applied magnetic field as weak as 2 mT. Simulations indicated that this anisotropy arose due to the zero field splitting of the electronic state in each triplet exciton. The direction of the external magnetic field altered the singlet component of the eigenstates of the Hamiltonian, and therefore altered the timeaverage of the singlet probability of a triplet exciton pair. This is different to the already established mechanism under a strong magnetic field, where the anisotropy arises from level crossings of eigenstates.
18
Kanaan, Mona N. "Cross-spectral analysis for spatial point-lattice processes". Thesis, [n.p.], 2000. http://dart.open.ac.uk/abstracts/page.php?thesisid=94.
Pełny tekst źródła
19
Agarwal, Shweta S. "QUADRATURE PHASE SHIFT KEYING-DIRECT SEQUENCE SPREAD SPECTRUM-CODE DIVISION MULTIPLE ACCESS WITH DISPARATE QUADRATURE CHIP AND DATA RATES". Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1134508354.
Pełny tekst źródła
20
Clive, Sally. "Clinical phase 1, pharmacodynamic and pharmacokinetic evaluation of Antagonist G, a broad-spectrum neuropeptide growth factor antagonist". Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325225.
Pełny tekst źródła
21
Ma, Andy Kin-Wan. "Directional spectrum model for phase space modelling in Monte Carlo simulations for a medical linear accelerator in radiotherapy". Thesis, University of Surrey, 2006. http://epubs.surrey.ac.uk/843473/.
Pełny tekst źródłaStreszczenie:
Cancer is the number two killer after cardiovascular diseases according to the World Health Organisation. It is generally accepted that about 50-55 % of all cancer patients benefit from radiotherapy treatment in which high-energy photons from medical linear accelerators (linacs) are commonly used. It is the goal of 3D conformal radiotherapy and intensity modulated radiotherapy (IMRT) to maximise the radiation dose to the tumour site while minimising the dose to the surrounding normal tissues. Thus the radiation beam is shaped to conform to the tumour outline by the multileaf collimator (MLC). Fast and accurate dose calculation is essential to the success of the treatment. The current method of choice is the superposition/convolution method for its computation efficiency but the complexity of the algorithm grows as the treatment moves into complicated regimes. The Monte Carlo method, on the other hand, uses one algorithm for different treatment regimes and its accuracy has been well proven. The drawback of the Monte Carlo method is in its computationally intensive and time-consuming nature. In a Monte Carlo simulation of a linac, it is common practice to divide the process into steps so that duplicate simulation of the patient-independent components can be avoided. Furthermore, the data of all particles emerging from any linac component form a phase space. A summary of these data allows, in principle, the generation of unlimited number of particles for simulations downstream. This summary is known as phase space model. This thesis examines different phase space models generated from the simulation of the patient-independent components. Under investigation is the 6 MV beam from the Elekta SLi linac. Two well-known phase space models, the point source model (PSM) and the multiple source model (MSM), were successfully implemented with MCNPX version 2.4.0. A new model termed the directional spectrum model (DSM) was proposed. In contrast to the PSM and the MSM which loosely relate the particle energy to its direction, the DSM couples the energy spectrum directly to the flight direction so that the scattering properties in the linac head are well accounted for. The DSM calculated dose distributions compare favourably with measurements in water phantom. It performs well inside and outside the 5x5, 10x10 and 20x20 cm2 fields. The confidence limits are generally within the American Association of Physicists in Medicine recommended tolerance of 2 % on central axis (CAX) beyond the depth of maximum dose (dmax) and 3 % in other low dose gradient regions. The shifts in the high dose gradient regions are also within the recommended tolerance of 2 mm. These shifts were measured in the dose build-up regions before dmax and in the isodose curves in a diamond-shaped field. The DSM also performs satisfactorily in the dose profiles formed by a single leaf of the MLC in a large field. After convolution with a Gaussian kernel, near perfect matches were obtained between the DSM calculated profiles and the RK, chamber measured ones. Since statistical fluctuations are unavoidable in any Monte Carlo calculations, denoising techniques from the image processing community could be invaluable tools in smoothing out the statistical noise in the dose distributions. The two digital filters assessed in this work are a Gaussian filter and a median filter. The median filter preserves the beam edges better than the Gaussian one. The smoothed isodose curves also have shifts within the recommended tolerance. This study indicates that the DSM, possibly together with denoising techniques, is a good candidate for IMRT calculations. Further studies should be carried out to confirm the DSM performance over a wider range of assessments including the modelling of higher energy linacs.
22
Li, Hongxiang. "Performance of Multitone Direct Sequence Spread Spectrum in the Presence of Imperfect Carrier Synchronization". Ohio University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1103057412.
Pełny tekst źródła
23
Oprisan, Ana. "Fluctuations, Phase Separation and Wetting Films near Liquid-Gas Critical Point". ScholarWorks@UNO, 2006. http://scholarworks.uno.edu/td/435.
Pełny tekst źródłaStreszczenie:
Gravity on Earth limits the study of the properties of pure fluids near critical point because they become stratified under their own weight. Near the critical point, all thermodynamic properties either diverge or converge and the heating and cooling cause instabilities of the convective flow as a consequence of the expansibility divergence. In order to study boiling, fluctuation and phase separation processes near the critical point of pure fluids without the influence of the Earth's gravity, a number of experiments were performed in the weightlessness of Mir space station. The experimental setup called ALICE II instrument was designed to suppress sedimentation and buoyancy-driven flow. Another set of experiments were carried out on Earth using a carefully density matched system of deuterated methanolcycloxexane to observe critical fluctuations directly. The set of experiments performed on board of Mir space station studied boiling and wetting film dynamics during evaporation near the critical point of two pure fluids (sulfur hexafluoride and carbon dioxide) using a defocused grid method. The specially designed cell containing the pure fluid was heated and, as a result, a low contrast line appeared on the wetting film that corresponded to a sharp change in the thickness of the film. A large mechanical response was observed in response to the cell heating and we present quantitative results about the receding contact lines. It is found that the vapor recoil force is responsible for the receding contact line. Local density fluctuations were observed by illuminating a cylindrical cell filled with the pure fluid near its liquid- gas critical point and recorded using a microscope and a video recorder. Microscopic fluctuations were analyzed both in sulfur hexafluoride and in a binary mixture of methanol cyclohexane. Using image processing techniques, we were able to estimate the properties of the fluid from the recorded images showing fluctuations of the transmitted and scattered light. We found that the histogram of an image can be fitted to a Gaussian relationship and by determining its width we were able to estimate the position of the critical point. The characteristic length of the fluctuations corresponding to the maximum of the radial average of the power spectrum was also estimated. The power law growth for the early stage of the phase separation was determined for two different temperature quenches in pure fluid and these results are in agreement with other experimental results and computational simulations.
24
Valenta, Václav. "Frequency synthesis for cognitive multi-radio". Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00597461.
Pełny tekst źródłaStreszczenie:
This doctoral thesis deals with design aspects of a reconfigurable frequency synthesizer for flexible radio transceivers in future cognitive multi-radios. The frequency bandwidth to be covered by this multi-radio synthesizer corresponds to the frequency bands of the most diffused wireless communication standards in the frequency band 800 MHz to 6 GHz. Since multi-standard operation is required, the synthesizer must fulfil the most stringent and sometimes conflicting requirements. Given these requirements, a novel approach for multi-mode frequency synthesis has been conceived. A hybrid phase locked loop based frequency synthesizer has been proposed and a novel switching protocol has been presented and validated on an experimental evaluation board. This approach combines fractional-N and integer-N modes of operation with switched loop filter topology. Compared to standard PLL techniques, the hybrid configuration provides a great flexibility in terms of reconfiguration and moreover, it offers relatively low circuit complexity and low power consumption. This architecture provides reconfiguration of the loop bandwidth, frequency resolution, phase noise and settling time performance and hence, it can adapt itself to diverse requirements given by the concerned wireless communication standards. Corresponding analyses, simulations and measurements have been carried out in order to verify the performance and functionality of the proposed solution. A part from the design of the multiband frequency synthesizer, a set of regional measurements of the radio spectrum utilization has been carried out in the framework of this dissertation research. These measurements are based on the energy detection principle and provide a close look at the degree of radio spectrum utilization in different regions, namely in the city of Brno in the Czech Republic and in the city of Paris and one of its suburbs in France. The goal of the experimental measurement campaign has been to estimate the degree of radio spectrum usage in a particular environment and to point out the fact that a new approach for radio spectrum management is inevitable
25
Kleinschmidt, Tristan Friedrich. "Robust speech recognition using speech enhancement". Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/31895/1/Tristan_Kleinschmidt_Thesis.pdf.
Pełny tekst źródłaStreszczenie:
Automatic Speech Recognition (ASR) has matured into a technology which is becoming more common in our everyday lives, and is emerging as a necessity to minimise driver distraction when operating in-car systems such as navigation and infotainment. In “noise-free” environments, word recognition performance of these systems has been shown to approach 100%, however this performance degrades rapidly as the level of background noise is increased. Speech enhancement is a popular method for making ASR systems more ro- bust. Single-channel spectral subtraction was originally designed to improve hu- man speech intelligibility and many attempts have been made to optimise this algorithm in terms of signal-based metrics such as maximised Signal-to-Noise Ratio (SNR) or minimised speech distortion. Such metrics are used to assess en- hancement performance for intelligibility not speech recognition, therefore mak- ing them sub-optimal ASR applications. This research investigates two methods for closely coupling subtractive-type enhancement algorithms with ASR: (a) a computationally-efficient Mel-filterbank noise subtraction technique based on likelihood-maximisation (LIMA), and (b) in- troducing phase spectrum information to enable spectral subtraction in the com- plex frequency domain. Likelihood-maximisation uses gradient-descent to optimise parameters of the enhancement algorithm to best fit the acoustic speech model given a word se- quence known a priori. Whilst this technique is shown to improve the ASR word accuracy performance, it is also identified to be particularly sensitive to non-noise mismatches between the training and testing data. Phase information has long been ignored in spectral subtraction as it is deemed to have little effect on human intelligibility. In this work it is shown that phase information is important in obtaining highly accurate estimates of clean speech magnitudes which are typically used in ASR feature extraction. Phase Estimation via Delay Projection is proposed based on the stationarity of sinusoidal signals, and demonstrates the potential to produce improvements in ASR word accuracy in a wide range of SNR. Throughout the dissertation, consideration is given to practical implemen- tation in vehicular environments which resulted in two novel contributions – a LIMA framework which takes advantage of the grounding procedure common to speech dialogue systems, and a resource-saving formulation of frequency-domain spectral subtraction for realisation in field-programmable gate array hardware. The techniques proposed in this dissertation were evaluated using the Aus- tralian English In-Car Speech Corpus which was collected as part of this work. This database is the first of its kind within Australia and captures real in-car speech of 50 native Australian speakers in seven driving conditions common to Australian environments.
26
Durgut, Suleyman. "Evidence of a narrow structure in ϓ(1S)l⁺l⁻ mass spectrum and CMS Phase I and II silicon detector upgrade studies". Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6411.
Pełny tekst źródłaStreszczenie:
This thesis focuses on two parts, the evidence of a structure in a four lepton final state, and the CMS detector upgrade studies.
The first part of the thesis focuses on an unexpected structure in Υ(1S)l+l− final state, where Υ(1S) → μ+μ−, l can represent a muon or an electron and m(l+l−) is required to be below the Υ(1S) mass. Using an integrated luminosity of 25.6 fb−1 recorded in proton-proton collisions at √s = 7 TeV and √s = 8 TeV with the CMS detector at the CERN LHC, an excess in the mass distribution near 18.5 GeV of Υ(1S)l+l− is found. The mass of this enhancement is found out to be 18.4 ± 0.1 (stat.) ± 0.2 (syst.) GeV in the Υ(1S)μ+μ− channel, and 18.5 ± 0.2 (stat.) ± 0.2 (syst.) GeV in the Υ(1S)e+e− channel. For the two results combined, the enhancement is found out to be 18.4 ± 0.1 (stat.) ± 0.2 (syst.) GeV with a local statistical significance of 4.9 standard deviations and a global significance, after taking into account the look-elsewhere-effect, of 3.6 standard deviations. The width of the observed enhancement is consistent with the mass resolution of the CMS detector.
The second part of the thesis focuses on detector upgrade studies for the silicon detector. The LHC has been increasing and will increase the luminosity and collision energy. Due to radiation damage and increasing data loss, the CMS detector underwent a Phase I upgrade in 2016/2017 and will undergo a Phase II upgrade in 2018/2019. In Phase I upgrade, silicon sensors and DC-DC converters were tested at Fermilab for the CMS Forward Pixel detector. For Phase II upgrade, a gantry robot system is built for module assemble at Fermilab for the CMS Outer Tracker detector.
27
Cheng, Hui. "Data integration and visualization for systems biology data". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77250.
Pełny tekst źródłaStreszczenie:
Systems biology aims to understand cellular behavior in terms of the spatiotemporal interactions among cellular components, such as genes, proteins and metabolites. Comprehensive visualization tools for exploring multivariate data are needed to gain insight into the physiological processes reflected in these molecular profiles. Data fusion methods are required to integratively study high-throughput transcriptomics, metabolomics and proteomics data combined before systems biology can live up to its potential. In this work I explored mathematical and statistical methods and visualization tools to resolve the prominent issues in the nature of systems biology data fusion and to gain insight into these comprehensive data.
In order to choose and apply multivariate methods, it is important to know the distribution of the experimental data. Chi square Q-Q plot and violin plot were applied to all M. truncatula data and V. vinifera data, and found most distributions are right-skewed (Chapter 2). The biplot display provides an effective tool for reducing the dimensionality of the systems biological data and displaying the molecules and time points jointly on the same plot. Biplot of M. truncatula data revealed the overall system behavior, including unidentified compounds of interest and the dynamics of the highly responsive molecules (Chapter 3). The phase spectrum computed from the Fast Fourier transform of the time course data has been found to play more important roles than amplitude in the signal reconstruction. Phase spectrum analyses on in silico data created with two artificial biochemical networks, the Claytor model and the AB2 model proved that phase spectrum is indeed an effective tool in system biological data fusion despite the data heterogeneity (Chapter 4). The difference between data integration and data fusion are further discussed. Biplot analysis of scaled data were applied to integrate transcriptome, metabolome and proteome data from the V. vinifera project. Phase spectrum combined with k-means clustering was used in integrative analyses of transcriptome and metabolome of the M. truncatula yeast elicitation data and of transcriptome, metabolome and proteome of V. vinifera salinity stress data. The phase spectrum analysis was compared with the biplot display as effective tools in data fusion (Chapter 5). The results suggest that phase spectrum may perform better than the biplot.
This work was funded by the National Science Foundation Plant Genome Program, grant DBI-0109732, and by the Virginia Bioinformatics Institute.Ph. D.
28
Zhou, Dan. "Certains études sur la minimalité et la propriété chaotique de dynamiques p-adicques et la régularité locale des series de Davenport avec translation de phase". Thesis, Paris Est, 2009. http://www.theses.fr/2009PEST0025.
Pełny tekst źródłaStreszczenie:
Dans cette thèse, nous étudions la minimalité et la propriété chaotique de systèmes dynamiques p-adiques. Nous étudions aussi des propriétés multifractales des séries de Davenport avec translation de phases. Dans la première partie, nous commençons par l'étude des systèmes dynamiques affines sur Zp. Nous trouvons une condition nécessaire et suffisante pour qu'un tel système soit minimal. En outre, nous exhibons toutes ses composantes strictement ergodiques si le système n'est pas minimal. De plus, nous étudions aussi les systèmes monômes sur le groupe 1+pZp. Ensuite nous étudions les polynômes localement dilatants et transitifs. Pour un tel polynôme, limité sur son ensemble de Julia, nous prouvons qu'il est conjugué à un sous-shift de type fini. Dans la deuxième partie, nous étudions les séries de Davenport avec translation de phases. Après avoir calculé le saut d'une telle série à chaque point, nous trouvons l'ensemble des points discontinus et obtenons une condition nécessaire et suffisante pour qu'une série de Davenport avec translation de phases soit continue sur R. La convergence ponctuelle de la série est aussi étudiée. Ensuite, nous estimons la borne inférieure de l'exposant hölderien de la série de Davenport avec de phase rationnelle et la borne supérieure du spectre de la singularitéIn this thesis, we study the minimality and the chaotic property of p-adic dynamical systems and some multifractal properties of phase translated Davenport series. In the first part, we begin with the study of affine dynamical systems on Zp. We find a necessary and sufficient condition for such a system to be minimal. Furthermore, all its strictly ergodic components are exhibited when it is not minimal. In addition, we study monomial systems on the group 1 + pZp. Then transitive locally expanding polynomial systems are studied. It is proved that such a polynomial system, restricted to its Julia set, is conjugate to a subshift of finite type. In the second part, we study phase translated Davenport series. After having calculated the jump of the series at each point, we characterize the set of discontinuous points and get a sufficient and necessary condition for the series to be continuous on R. Furthermore, the pointwise convergence of the series is studied. Then we estimate the lower bound of the Hölder-exponent of rational translated Davenport series and get an upper bound estimation on the spectrum of singularity. The lower bound of the Hölder-exponent are also discussed for some irrational translated series
29
Mashayekhi-Nezamabadi, Kaveh. "The protein synthesis spectrum during the induction phase of somatic embryogenesis in Carrot (Daucus carota L.) cultures and the role of nitrogen forms for embryo development". [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=963447823.
Pełny tekst źródła
30
Sargeant, H. "PREDETECTION RECORDING TECHNIQUES FOR GPS SIGNALS". International Foundation for Telemetering, 1986. http://hdl.handle.net/10150/615545.
Pełny tekst źródłaStreszczenie:
International Telemetering Conference Proceedings / October 13-16, 1986 / Riviera Hotel, Las Vegas, NevadaPredetection recording of spread-spectrum (SS) signals such as GPS transmissions is a desirable objective for both users and developers of equipment designed to receive such signals. (GPS user-equipment development is a lengthy process during which signal simulators are only partially useful.) Upon playback, GPS signals are used by the same or modified receivers so that acquisition, processing, detection and tracking loops can be altered to optimize the receiver parameters. Development of predetect SS signal recording systems is difficult to achieve in practice. Such systems not only must be of suitable phase linearity to preserve the signal content to be extracted but sometimes must also preserve the exact signal-to-noise ratio (SNR) characteristics of the recorded signals. Existing conventional test equipment is unsuitable for deriving value judgments of the quality of a predetect recording system’s output because the SS signal has a negative SNR. This paper reveals that it is possible to use, for this purpose, tape recorders now available on many test ranges in combination with auxiliary equipment similar to that designed for the U.S. Navy’s TRIDENT Program (recording C/A-code data from in-flight missile translators). The basic techniques are described in some detail to enable potential users to understand the necessary equipment concepts and evaluate the author’s approach in terms of their own applications.
31
De, Sanctis Silvia [Verfasser], i Hans Robert [Akademischer Betreuer] Kalbitzer. "Application of Singular Spectrum Analysis (SSA), Independent Component Analysis (ICA) and Empirical Mode Decomposition (EMD) for automated solvent suppression and automated baseline and phase correction from multi-dimensional NMR spectra / Silvia De Sanctis. Betreuer: Hans Robert Kalbitzer". Regensburg : Universitätsbibliothek Regensburg, 2011. http://d-nb.info/1030178941/34.
Pełny tekst źródła
32
Hafez, Torbati Mohsen [Verfasser], Götz Silvester [Akademischer Betreuer] Uhrig i Kai Phillip [Gutachter] Schmidt. "Excitation spectrum and quantum phase transitions in the one-dimensional ionic Hubbard model : Continuous unitary transformations approach / Mohsen Hafez Torbati. Betreuer: Götz Silvester Uhrig. Gutachter: Kai Phillip Schmidt". Dortmund : Universitätsbibliothek Dortmund, 2014. http://d-nb.info/1107560314/34.
Pełny tekst źródła
33
Згуровський, Артур Андрійович, i Artur Zghurovskyi. "Метод кодування мовних сигналів для комунікаційних систем". Master's thesis, Тернопільський національний технічний університет імені Івана Пулюя, 2020. http://elartu.tntu.edu.ua/handle/lib/33949.
Pełny tekst źródłaStreszczenie:
Кваліфікаційну роботу магістра присвячено аналізу методу кодування мовних сигналів для комунікаційних систем. Розглянуто переваги та недоліки відомих методів кодування і виділено переваги фазових вокодерів. Проведено оцінювання параметрів голосових сигналів, що використовуються при кодуванні їх в фазових вокодерахThe master's thesis is devoted to the analysis of the method of coding speech signals for communication systems. The advantages and disadvantages of known coding methods are considered and the advantages of phase vocoders are highlighted. The parameters of voice signals used in their encoding in phase vocoders are evaluated.
ВСТУП РОЗДІЛ 1. АНАЛІТИЧНА ЧАСТИНА 1.1 Задача побудови вокодерів 1.2 Характеристики та структурні параметри голосу 1.3 Висновки до розділу 1. РОЗДІЛ 2. ОСНОВНА ЧАСТИНА.. 2.1 Параметризація мовного сигналу….. 2.2 НТК - архітектура і можливості. 2.3 Технологія моделювання систем розпізнавання мови з застосуванням інструментарію НТК… 2.4 Результати експериментальних досліджень…. 2.5 Висновки до розділу 2…. РОЗДІЛ 3.НАУКОВО-ДОСЛІДНА ЧАСТИНА…. 3.1 Вимірювання параметрів фільтрів мовних сигналів… 3.2 Вимірювання частоти основного тону…. 3.3 Формування збудливого сигналу... 3.4 Синтез: відновлення мовного сигналу.. 3.5 Висновки до розділу 3…. РОЗДІЛ 4.СПЕЦІАЛЬНА ЧАСТИНА…. 4.1 Метрологічне забезпечення наукового дослідженя… 4.2Побудова прикладного програмного забезпечення для розв’язування наукової задачі… 4.3 Висновки до розділу 4… РОЗДІЛ 5.ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІ-ЯХ…. 5.1 Охорона праці…. 5.1.1 Планування заходів з охорони праці. Види планування та контролю стану охорони праці… 5.1.2 Особливості розслідування та обліку нещасних випадків невиробничого характеру. 5.1.3 Пожежна сигналізація і зв'язок. Засоби гасіння пожеж. Протипожежне водопостачання. Первинні засоби пожежогасіння Автоматичні засоби пожежогасіння на об'єктах галузі...... 5.2 Безпека в надзвичайних ситуаціях……. 5.3 Висновки до розділу 5…. ЗАГАЛЬНІ ВИСНОВКИ…….. СПИСОК ВИКОРИСТАНИХ ДЖЕРЕЛ….. ДОДАТКИ.....
34
Čada, David. "Spektrální analyzátor do 500 MHz". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221242.
Pełny tekst źródłaStreszczenie:
This project deals with design and realization of the spectrum analyser using double superheterodyne topology with frequency range up to 500MHz. This work solves hardware blocks like phase lock loops, intermediate frequency filters, saw filter, crystal filter, logarithmic detector. Content of work is also design description and tuning of spectrum analyzer parts.
35
O'Hair, Richard Alfred John. "Studies in gas phase ion chemistry : a thesis presented for the degree of Doctor of Science in the Faculty of Science of the University of Adelaide /". Title page, table of contents and summary only, 2004. http://web4.library.adelaide.edu.au/theses/09SD/09sdo362.pdf.
Pełny tekst źródła
36
HENKE, EV. "Knock out - a missing C1s line in the photoelectron spectrum of aqueous chloral hydrate : Core electron spectroscopy of chloral hydrate, trichloroethanol and ethanol in aqueous solution and gas phase". Thesis, Uppsala University, Department of Physics and Astronomy, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-126257.
Pełny tekst źródłaStreszczenie:
Chloral hydrate Cl3C-C(OH)2H in aqueous solution has been studied by photoelectron spectroscopy using synchrotron radiation. The expected separation between the two carbon 1s lines due to different chemical environments could not be observed in the aqueous solution, but was clearly seen in following gas phase measurements. NMR measurements excluded sample damage in the aqueous solution and support the image of coincidence of the two carbon lines. The coincidence of the two lines is discussed in terms of experimental resolution and change in chemical shift in the aqueous phase. The observations are further compared to measurements of trichloroethanol and ethanol, which both exhibit the same characteristic C-C bond and at least one hydroxyl group. The present data showed no clear evidence of change in chemical shift in aqueous solution as compared to the gas phase, but such an effect might not be completely excluded.
The liquid measurements were performed using a liquid micro-jet, a recently developed technique for accessing volatile liquids in a high vacuum environment as required for photoelectron spectroscopy. The set-up is described in detail.
During the present project, I was involved into planning and performing experiments, sample preparation, data analysis and discussion.
37
Al-Sharari, Hamed. "An implementation of acquisition using transform domain/cycle code shift keying system on a multipath channel". Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1177004799.
Pełny tekst źródła
38
Kota, Akash. "Spectral Analysis of Bragg and Non-Bragg Orders in Dynamic Holography Using Photorefractive Materials". University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1470323121.
Pełny tekst źródła
39
LE, BLANC ALAIN. "Reactions unimoleculaires en phase gazeuse, de radicaux cations bifonctionnels : beta ceto-alcool, beta ceto-esters et de cations beta ceto-acylium". Paris 6, 1988. http://www.theses.fr/1988PA066349.
Pełny tekst źródłaStreszczenie:
Une introduction generale sur la spectrometrie de masse precede une premiere partie portant sur l'interpretation des fragmentations de la dimethyl-3,3 hydroxy-4 butanone-2 a basse energie. Une seconde partie est reservee aux fragmentations de plusieurs beta ceto-esters diversement substitues. Dans une troisieme partie sont examinees les decompositions unimoleculaires d'ions acylium beta carbonyles de faible energie interne. L'accent est mis, tout au long de ce travail, sur le role essentiel des atomes d'oxygene dont la presence induit des ruptures caracteristiques mais aussi sert de relais aux transferts d'hydrogenes
40
Murach, Thomas. "Monoscopic Analysis of H.E.S.S. Phase II Data on PSR B1259–63/LS 2883". Doctoral thesis, Humboldt-Universität zu Berlin, 2017. http://dx.doi.org/10.18452/18484.
Pełny tekst źródłaStreszczenie:
Cherenkov-Teleskope sind in der Lage, das schwache Cherenkovlicht aus Teilchenschauern zu detektieren, die von kosmischen Teilchen mit Energien von ca. 100 GeV bis 100 TeV in der Erdatmosphäre initiiert werden. Das Ziel ist die Detektion von Cherenkovlicht aus Schauern, die von Gammastrahlen erzeugt wurden, der größte Teil der Schauer stammt jedoch von geladenen Teilchen. Im Jahr 2012 wurde das H.E.S.S.-Observatorium in Namibia, bis dahin bestehend aus vier Teleskopen mit 100 m²-Spiegeln, um ein fünftes Teleskop mit einer Spiegelfläche von ca. 600 m² ergänzt. Aufgrund der großen Spiegelfläche besitzt dieses Teleskop die niedrigste Energieschwelle aller Teleskope dieser Art. In dieser Dissertation wird ein schneller Algorithmus namens MonoReco präsentiert, der grundlegende Eigenschaften der Gammastrahlen wie ihre Energien und Richtungen rekonstruieren kann. Dieser Algorithmus kann weiterhin unterscheiden, ob Schauer von Gammastrahlen oder von geladenen Teilchen der kosmischen Strahlung initiiert wurden. Diese Aufgaben werden mit mithilfe von künstlichen neuronalen Netzwerken erfüllt, welche ausschließlich die Momente der Intensitätsverteilungen in der Kamera des neuen Teleskops analysieren. Eine Energieschwelle von 59 GeV und Richtungsauflösungen von 0.1°-0.3° werden erreicht. Das Energiebias liegt bei wenigen Prozent, die Energieauflösung bei 20-30%. Unter anderem mit dem MonoReco-Algorithmus wurden Daten, die in der Zeit um das Periastron des Binärsystems PSR B1259-63/LS 2883 im Jahre 2014 genommen wurden, analysiert. Es handelt sich hierbei um einen Neutronenstern, der sich in einem 3,4-Jahres-Orbit um einen massereichen Stern mit einer den Stern umgebenden Scheibe aus Gas und Plasmen befindet. Zum ersten Mal konnte H.E.S.S. das Gammastrahlenspektrum dieses Systems bei Energien unterhalb von 200 GeV messen. Weiterhin wurde bei erstmaligen Beobachtungen zur Zeit des Periastrons ein lokales Flussminimum gemessen. Sowohl vor dem ersten als auch nach dem zweiten Transit des Neutronensterns durch die Scheibe wurden hohe Flüsse gemessen. Im zweiten Fall wurden Beobachtungen erstmals zeitgleich mit dem Fermi-LAT-Experiment durchgeführt, das wiederholt sehr hohe Flüsse in diesem Teil des Orbits messen konnte. Ein Vergleich der gemessenen Flüsse mit Vorhersagen eines leptonischen Modells zeigt gute Übereinstimmungen.Cherenkov telescopes can detect the faint Cherenkov light emitted by air showers that were initiated by cosmic particles with energies between approximately 100 GeV and 100 TeV in the Earth's atmosphere. Aiming for the detection of Cherenkov light emitted by gamma ray-initiated air showers, the vast majority of all detected showers are initiated by charged cosmic rays. In 2012 the H.E.S.S. observatory, until then comprising four telescopes with 100 m² mirrors each, was extended by adding a much larger fifth telescope with a very large mirror area of 600 m². Due to the large mirror area, this telescope has the lowest energy threshold of all telescopes of this kind. In this dissertation, a fast algorithm called MonoReco is presented that can reconstruct fundamental properties of the primary gamma rays like their direction or their energy. Furthermore, this algorithm can distinguish between air showers initiated either by gamma rays or by charged cosmic rays. Those tasks are accomplished with the help of artificial neural networks, which analyse moments of the intensity distributions in the camera of the new telescope exclusively. The energy threshold is 59 GeV and angular resolutions of 0.1°-0.3° are achieved. The energy reconstruction bias is at the level of a few percent, the energy resolution is at the level of 20-30%. Data taken around the 2014 periastron passage of the gamma-ray binary PSR B1259-63/LS 2883 were analysed with, among others, the MonoReco algorithm. This binary system comprises a neutron star in a 3.4 year orbit around a massive star with a circumstellar disk consisting of gas and plasma. For the first time the gamma-ray spectrum of this system could be measured by H.E.S.S. down to below 200 GeV. Furthermore, a local flux minimum could be measured during unprecedented measurements at the time of periastron. High fluxes were measured both before the first and after the second transit of the neutron star through the disk. In the second case measurements could be performed for the first time contemporaneously with the Fermi-LAT experiment, which has repeatedly detected very high fluxes at this part of the orbit. A good agreement between measured fluxes and predictions of a leptonic model is found.
41
Chausse, Jean-Pierre. "Etude par une methode de melange, de l'organisation et des conformations moleculaires dans les mesophases hautement ordonnees". Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF2E383.
Pełny tekst źródłaStreszczenie:
Etude des influences respectives des coeurs aromatiques et des chaines aliphatiques sur la nature du polymorphisme des cristaux liquides thermotropes. La methode de melange binaire consiste a etudier les modificaitons de l'organisation et du comportement moleculaire lorsque le milieu est perturbe par adjonction de molecules a chaines courtes parmi les molecules a chaines longues. Le melange de deux derives des bases de schiff, le 40. 2 et le 40. 8, en phase smectique b est essentiellement utilise. Techniques d'analyse : microscopie, diffraction rx, dilatometrie, spectre rmn du deuterieur et spectre rpe
42
Jerkstrand, Anders. "Spectral modeling of nebular-phase supernovae". Doctoral thesis, Stockholms universitet, Institutionen för astronomi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-64130.
Pełny tekst źródłaStreszczenie:
Massive stars live fast and die young. They shine furiously for a few million years, during which time they synthesize most of the heavy elements in the universe in their cores. They end by blowing themselves up in a powerful explosion known as a supernova (SN). During this process, the core collapses to a neutron star or a black hole, while the outer layers are expelled with velocities of thousands of kilometers per second. The resulting fireworks often outshine the entire host galaxy for many weeks. The explosion energy is eventually radiated away, but powering of the newborn nebula continues by radioactive isotopes synthesized in the explosion. The ejecta are now quite transparent, and we can see the material produced in the deep interiors of the star. To interpret the observations, detailed spectral modeling is needed. This thesis aims to develop and apply state-of-the-art computational tools for interpreting and modeling SN observations in the nebular phase. This requires calculation of the physical conditions throughout the nebula, including non-thermal processes from the radioactivity, thermal and statistical equilibrium, as well as radiative transport. The inclusion of multiline radiative transfer, which we compute with a Monte Carlo technique, represents one of the major advancements presented in this thesis. On February 23 1987, the first SN observable by the naked eye since 1604 exploded, SN 1987A. Its proximity has allowed unprecedented observations, which in turn have lead to significant advancements in our understanding of SN explosions. As a first application of our model, we analyze the 44Tipowered phase (t & 5 years) of SN 1987A. We find that a magnetic field is present in the nebula, trapping the positrons that provide the energy input, and resulting in strong iron lines in the spectrum. We determine the 44Ti mass to 1.5(+0.5−0.5)*10−4 M⊙. From the near-infrared spectrum at an age of 19 years, we identify strong emission lines from explosively synthesized metals such as silicon, calcium, and iron. We use integral-field spectroscopy to construct three-dimensional maps of the ejecta, showing a morphology suggesting an asymmetric explosion. The model is then applied to the close-by and well-observed Type IIP SN 2004et, analyzing its ultraviolet to mid-infrared evolution. Based on its Mg I] 4571 Å, Na I 5890, 5896 Å, [O I] 6300, 6364 Å, and [Ne II] 12.81 mm nebular emission lines, we determine its progenitor mass to be around 15 M⊙. We confirm that silicate dust, SiO, and CO have formed in the ejecta. Finally, the major optical emission lines in a sample of Type IIP SNe areanalyzed.We find that most spectral regions in Type IIP SNe are dominated by emission from the massive hydrogen envelope, which explains the relatively small variation seen in the sample. We also show that the similar line profiles seen from all elements suggest extensive mixing occurring in most hydrogenrich SNe.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Accepted.
43
Lemiti, Mustapha. "Couches de dioxyde de silicium obtenues par dépôt chimique à partir d'une phase gazeuse (C. V. D. ) : élaboration et caractérisation". Lyon 1, 1985. http://www.theses.fr/1985LYO19022.
Pełny tekst źródłaStreszczenie:
Nous avons mis au point un dispositif permettant d'élaborer des couches de SiO₂ à partir d'une phase gazeuse (C. V. D. ). Le procédé consiste à hydrolyser un composé halogéné (SiCl₄) par de la vapeur d'eau, au voisinage d'un substrat de silicium suivant la réaction : SiC1₄+ 2H₂0 -> Si0₂ + 4HC1. Les dépôts ont été réalisés essentiellement à température ambiante. L'influence des paramètres expérimentaux sur la cinétique de dépôt a été; étudiée. L'analyse physico-chimique des couches ainsi obtenues (ellipsométrie, Raman, Auger, décharge luminescente) nous a renseigné sur la nature des liaisons, la stœchiométrie et le profil des impuretés dans la couche. Après optimisation des paramètres, des structures MOS ont été réalisées pour étudier les défauts électriquement actifs dans l'oxyde et à l'interface Si-Si0₂. Par les méthodes classiques (C(V), G(V), I(V), C(ω,T), G(ω,T), nous avons évalué la densité d'états d'interface qui varie autour de 10¹¹ eV⁻¹ cm⁻² et les charges dans l'oxyde à 10¹² ch. /cm. L'influence de certains paramètres expérimentaux sur les propriétés électriques des structures MOS a été dégagée.
44
Cardenas, Olaya Andrea. "Digital instrumentation for the measurement of high spectral purity signals". Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCD019/document.
Pełny tekst źródłaStreszczenie:
Les progrès sur la technologie électronique pendant les dernières années avaient permis l’utilisation des techniques numériques dans la métrologie de temps et fréquence où bas bruit et haute précision sont nécessaires. Ces techniques génèrent systèmes plus flexibles pour l’implémentation et pour la configuration. De cette façon, c’est possible d’obtenir systèmes de mesure avec capacités étendues, fonctionnalités ajoutées et plus facile ad utiliser.Les convertisseurs analogique-numérique (ADCs) et numérique-analogique (DACs), considérée comme l’interface avec le monde analogique, représentent la limite de la performance du système en termes de bruit. De plus, en général, les plateformes commerciales basées sur FPGA sont cadencées par un oscillateur à quartz dont précision et stabilité de fréquence ne sont pas adapté pour plupart des applications de temps e fréquence. Dans ce cas, c’est possible d’utiliser le Phase Locked Loop (PLL) intégré dans la FPGA pour générer l’horloge du système à partir d’une référence de fréquence externe. Cependant, en considérant que le bruit de phase du PLL pourrait dégrader la stabilité de la référence et ainsi limiter la performance d’entier système, le PLL devient un composant critique pour l’instrumentation numérique. L’information disponible actuellement dans la littérature décrit en détail les spécifications de ces composants a offset de fréquence loin de la porteuse. Cependant, l’information proche à la porteuse est une préoccupation plus importante pour les applications de temps et fréquence.Dans ce cadre, ma thèse de doctorat est concentrée sur l’étude des limitations des composants critiques de l’instrumentation numérique pour la métrologie de temps et fréquence. L’objectif est de caractériser le bruit introduit par ces composants et ainsi obtenir un modèle que permettra de prédire leurs effets sur une application spécifique. On propose une méthode pour extraire les paramètres des modelés lequel est testé et validé sur la plateforme commercial Red Pitaya. Cette plateforme est une open source embedded system dont résolution et vitesse (14 bit, 125 MSps) sont raisonnablement proche de l’état de l’art des ADCs et DACs (16 bit, 350 MSps or 14 bit, 1 GSps/3GSPs) et c’est potentiellement suffisant pour l’implémentation de un instrument complet. Les résultats de la caractérisation conduisent aux limitations de la plateforme et donnent une directrice pour le design de l’instrument.Basé sur les résultats obtenus de la caractérisation du bruit, l’implémentation de un instrument numérique pour le transfert de fréquence par fibre optique est été réalisée sur la plateforme Red Pitaya. Dans ce projet, une implémentation numérique pour la détection et compensation du bruit de phase induit par la fibre est proposé. Sur la base des résultats de la caractérisation, il était prévu une limitation de la mesure du bruit de phase donnée par le PLL. Les premières mesures de cette implémentation ont été réalisées sur un lien de fibre de 150 km + 150 km placées dans les mêmes câbles entre l'INRiM (Turin) et le Laboratoire Souterrain de Modane (LSM) à la frontière Italie-France. A partir de ces résultats, le bruit introduit par le système numérique a été vérifié en accord avec les résultats de la caractérisation. Additionnel tests et améliorations seront effectués pour avoir un système capable d’être utilisé sur le lien italien pour la fréquence et le temps de Turin à Florence qui est longue de 642 km et à son extension dans le reste de l'Italie prévue dans le prochain avenir.Actuellement, une plateforme plus performante est en cours d'évaluation, à travers les techniques et concepts développés au cours de la thèse. Ce projet a pour but l’implémentation d'un phasemètre à l’état de l’art de la technologie dont l'architecture est basée sur le DAC. La caractérisation du DAC est en cours de développement et les mesures préliminaires sont également rapportées iciImprovements on electronic technology in recent years have allowed the application of digital techniques in time and frequency metrology where low noise and high accuracy are required, yielding flexibility in systems implementation and setup. This results in measurement systems with extended capabilities, additional functionalities and ease of use.The Analog to Digital Converters (ADCs) and Digital to Analog Converters (DACs), as the system front-end, set the ultimate performance of the system in terms of noise. Moreover, most commercial platforms based on FPGA are clocked by quartz oscillators whose accuracy and frequency stability are not suitable for many time and frequency applications. In this case, it is possible to take advantage of the internal Phase Locked Loop (PLL) for generating the internal clock from an external frequency reference. However, the PLL phase noise could degrade the oscillator stability thereby limiting the entire system performance becoming a critical component for digital instrumentation. The information available currently in literature, describes in depth the features of these devices at frequency offsets far from the carrier. However, the information close to the carrier is a more important concern for time and frequency applications.In this frame, my PhD work is focused on understanding the limitations of the critical blocks of digital instrumentation for time and frequency metrology. The aim is to characterize the noise introduced by these blocks and in this manner to be able to predict their effects on a specific application. This is done by modeling the noise introduced by each component and by describing them in terms of general and technical parameters. The parameters of the models are identified and extracted through the corresponding method proposed accordingly to the component operation. This work was validated by characterizing a commercially available platform, Red Pitaya. This platform is an open source embedded system whose resolution and speed (14 bit, 125 MSps) are reasonably close to the state of the art of ADCs and DACs (16 bit, 350 MSps or 14 bit, 1 GSps/3GSPs) and it is potentially sufficient for the implementation of a complete instrument. The characterization results lead to the noise limitations of the platform and give a guideline for instrumentation design techniques.Based on the results obtained from the noise characterization, the implementation of a digital instrument for frequency transfer using fiber link was performed on the Red Pitaya platform. In this project, a digital implementation for the detection and compensation of the phase noise induced by the fiber is proposed. The beat note, representing the fiber length variations, is acquired directly with a high speed ADC followed by a fully digital phase detector. Based on the characterization results, it was expected a limitation in the phase noise measurement given by the PLL. First measurements of this implementation were performed using the 150 km-long buried fibers, placed in the same cables between INRiM and the Laboratoire Souterrain de Modane (LSM) on the Italy-France border. The two fibers are joined together at LSM to obtain a 300 km loop with both ends at INRiM. From these results the noise introduced by the digital system was verified in agreement with characterization results. Further test and improvements will be performed for having a finished system which is intended to be used on the Italian Link for Frequency and Time from Turin to Florence that is 642-km long and to its extension in the rest of Italy that is foreseen in the next future.Currently, a higher performance platform is under assessment by applying the tools and concepts developed along the PhD. The purpose of this project is the implementation of a state of the art phasemeter whose architecture is based on the DAC. The DAC characterization is under development and preliminary measurements are reported here
45
Remesh, Vikas. "Spectral phase control of nanoscale nonlinear optical responses". Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669719.
Pełny tekst źródłaStreszczenie:
The study of light-driven physical processes generated in nanomaterials require shorter (in time, or broader in frequency) laser pulses with techniques to tailor its phase and temporal/spectral characteristics at the nanoscopic interaction volume. Such studies can specifically address the aspect of coherence of excited states in molecular systems or of collective electronic oscillations in plasmonic nanoresonators. Addressing nonlinear coherent phenomena with broadband femtosecondpulses, usually involve achieving constructive or destructive interferences between multiple absorption pathways by spectral phase manipulation. Despite progress on in ultrafast spatiotemporal control of optical processes, a systematic, true optical coherent control on a fundamental dipole plasmon mode remained challenging due to the very short dephasing time of the plasmon oscillation in the 25 fs range. Unfortunately, luminescence is an incoherent process and therefore generally not explored for nanoscale coherent control of the antenna response. Firstly, we demonstrated that, in resonant gold nanoantennas, the two-photon absorption process can be coherent, provided that the excitation pulse duration is shorter than the dephasing time of plasmon mode oscillation. Exploiting this coherent response, we showed the pure spectral phase control of resonant gold nanoantennas, with effective read-out of the two-photon photoluminescence. High-index dielectric nanoantennas, for example, gallium phosphide (GaP) nanoantennas have recently emerged as promising alternatives to plasmonic nanoantennas displaying extremely low losses in the visible range and having high nonlinearities. They also support both multipolar electric and magnetic resonances in both visible and NIR frequency range. Especially, the low losses and large nonlinearities are promising for ultrafast optical switching and truly all-optical control of GaP nanodevices. Here first we used two-and three-photon excitation of GaP nanodisks to probe the size-dependent resonance enhancement of second-harmonic and bandgap emission. Next, we showed, by spectral phase control of broadband pulsed excitation, that GaP nanoantennas outperformed their metal counterparts in supporting nonlinear optical coherences. Next, our numerical studies on the SHG enhancement in GaP nanoantennas indicated that size-dependent SHG enhancement is the result of resonant electric field confinement in the nanoantenna volume. Study of angular emission pattern, combined with polarimetry of resonant nanoantennas revealed that SHG emission resulting from the excitation with linear polarization is predominantly radially polarized. The multipolar modal analysis at SHG frequency indicated the presence of an electric dipole oscillating along the disk axis, along with weak contributions of quadrupoles and octupoles. Finally, size-dependent SHG spectral shift confirmed the existence of multiple resonances in these nanodisks. Exploiting this feature, multipolar electromagnetic modes that resonate with relative phases, following a broadband laser illumination, can be made to interfere and the interference can be controlled by means of spectral phase modulation of the excitation field to achieve directionality. With an antisymmetric p step modulation, a switching in polarization state was observed. Our experiments pave way for all-optical control of directional radiation of nanoantennas by the control of multipolar interference in the nonlinear regime.El estudio de los procesos físicos impulsados por la luz generados en nanomateriales requiere pulsos láser más cortos (en el tiempo) con técnicas para adaptar sus características de fase y temporales ó espectrales en el volumen de interacción nanoscópica. Dichos estudios pueden abordar específicamente el aspecto de la coherencia de estados excitados en sistemas moleculares o de oscilaciones electrónicas colectivas en nanoresonadores plasmónicos. Abordar fenómenos coherentes no lineales con pulsos de femtosegundos de banda ancha, generalmente implica lograr interferencias constructivas o destructivas entre múltiples vías de absorción mediante manipulación de fase espectral. A pesar del progreso en el control espacio-temporal ultrarrápido de los procesos ópticos, un control coherente óptico sistemático y verdadero en un modo de plasmón dipolar fundamental seguía siendo desafiante debido al muy corto tiempo de decoherencia de la oscilación del plasmón en el rango de 25 fs. Desafortunadamente, la luminiscencia es un proceso incoherente y, por lo tanto, generalmente no ha sido explorado todavía para el control coherente a nanoescala de la respuesta de la antena. En primer lugar, demostramos que, en las nanoantenas de oro resonantes, el proceso de absorción de dos fotones puede ser coherente, siempre que la duración del pulso de excitación sea más corta que el tiempo de desfase de la oscilación del modo plasmonico. Aprovechando esta respuesta coherente, mostramos el control de la fase espectral pura de nanoantenas de oro resonantes, concolectando eficientemente de la fotoluminiscencia de dos fotones. Las nanoantenas dieléctricas de alto índice de refracción, por ejemplo, las nanoantenas de fosfuro de galio (GaP), han surgido recientemente como alternativas prometedoras a las nanoantenas plasmónicas que muestran scattering muy bajas extremadamente bajas en el rango visible y tienen altas no linealidades. También admiten resonancias magnéticas y eléctricas multipolares en el rango de frecuencia visible y NIR. Especialmente, las bajas scattering y las grandes no linealidades son prometedoras para una conmutación óptica ultrarrápida y un control puramente todo óptico de los nanodispositivos GaP. Aquí, primero, utilizamos la excitación de dos y tres fotones de los nanodiscos de GaP para probar la mejora de resonancia dependiente del tamaño de los nanodiscos de la emisión de segundo armónico y de la banda prohibida. A continuación, demostramos, mediante el control de fase espectral de la excitación pulsada de banda ancha, que las nanoantenas de GaP superaron a sus contrapartes metálicas en el generación de coherencias ópticas no lineales. A continuación, nuestros estudios numéricos sobre la mejora de SHG en las nanoantenas GaP indicaron que la mejora de SHG dependiente del tamaño es el resultado del confinamiento de campo eléctrico resonante en el volumen de nanoantena. El estudio del modelo de emisión angular, combinado con la polarimetría de nanoantenas resonantes reveló que la emisión de SHG resultante de la excitación con polarización lineal está predominantemente polarizada radialmente. El análisis modal multipolar a frecuencia SHG indicó la presencia de un dipolo eléctrico que oscila a lo largo del eje del disco, junto con contribuciones débiles de cuadrupolos y octopolos. Finalmente, el cambio espectral de SHG dependiente del tamaño confirmó la existencia de resonancias múltiples en estos nanodiscos. Aprovechando esta característica, los modos electromagnéticos multipolares que resuenan con fases relativas, después de una iluminación láser de banda ancha, pueden interferir y la interferencia puede controlarse mediante la modulación de fase espectral del campo de excitación para lograr la direccionalidad. Con una modulación de paso pi antisimétrica, se observó un cambio en el estado de polarización. Nuestros experimentos abren el camino para el control totalmente óptico de la radiación direccional de nanoantenas mediante el control de la interferencia multipolar en el régimen no lineal
46
Tiihonen, Mikael. "Spectral Management in Quasi-Phase-Matched Parametric Devices". Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4021.
Pełny tekst źródła
47
Coutinho, Fábio Rizental. "Um novo método ultrassônico para detecção da posição da interface em escoamentos bifásicos ar-água". Universidade Tecnológica Federal do Paraná, 2014. http://repositorio.utfpr.edu.br/jspui/handle/1/972.
Pełny tekst źródłaStreszczenie:
IBP; FINEPTécnicas de medição de velocidade baseadas em ultrassom vem sendo muito utilizadas atualmente para o estudo de escoamentos de fluidos devido ao seu caráter não intrusivo. Em escoamentos bifásicos ar-água, a grande dificuldade na aplicação dessa metodologia é resolver a que fase pertence a velocidade medida. Esse problema envolve a tarefa de determinar a posição da interface líquido-gás. O algoritmo de estimação de velocidade denominado de Velocity Matched Spectrum (VMS) se diferencia dos demais por apresentar como resultado um espectro de velocidades para cada volume amostral interrogado. Neste trabalho um método baseado no formato dessa curva espectral da velocidade é utilizado para gerar um mapeamento espaço-temporal, o qual, após aplicação de filtros espaciais, resulta na detecção acurada da posição da interface água-ar. Para isso, um sistema de medição que utiliza o estimador VMS foi desenvolvido e validado através de um experimento de escoamento em cilindro girante e de um escoamento horizontal monofásico turbulento. A ascensão de bolhas em líquido estagnado apresenta dificuldades na detecção da fronteira água-ar devido às mudanças abruptas na inclinação da interface da bolha no seu movimento de subida. É mostrado que a técnica proposta apresenta um erro RMS entre 1,71 a 3,39 e uma probabilidade de falha na detecção e de falsa detecção entre 0,89% a 11,9% na determinação da posição espaço-temporal da interface água-ar de um escoamento externo de ascensão de bolhas em líquido estagnado. Mostra-se que a exatidão na determinação é mantida mesmo no caso de um transdutor obstruído por uma chapa metálica, ou então, emitindo externamente a uma tubulação de acrílico.
Ultrasonic measurement techniques for velocity estimation are currently widely used in flow study due to its non-intrusive nature. The difficulty on the application of this methodology to a two-phase air-water flow is in deciding from which phase the velocity data measured comes from. This problem involves the task of evaluating gas-liquid interface position. The algorithm known as Velocity Matched Spectrum (VMS) is a velocity estimator that stands out from other methods by returning a spectrum of velocities for each interrogated volume sample. In this work a method based on velocity spectrum curve shape is used to generate a spatial-temporal mapping, which, after spatial filtering, yields an accurate contour of the air-water interface. Therefore, a measurement system that implements VMS estimator was developed and validated through a rotating cylinder and a horizontal single-phase pipe turbulent flow experiments. Interface detection of free-rising bubbles in quiescent liquid presents some difficulties for interface detection due to abrupt changes in interface inclination. It is showed that the proposed technique yields a RMS error between 1.71 to 3.39 and a probability of detection failure or false detection between 0.89% to 11.9% in determining the spatial-temporal gas-liquid interface position in the flow of free rising bubbles in stagnant liquid. This result is valid for both free path and with transducer emitting through a metallic plate or a Plexiglas pipe.
48
Métin, Jacques. "Etude structurale de fluorures ternaires de lanthanides et mecanismes de transfert d'energie gd**(3+) -> eu**(2+) dans rbgd : :(3)f::(10)". Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF2E391.
Pełny tekst źródłaStreszczenie:
Etude des systemes kf-prf::(3) et csf-luf::(3) par analyse thermique differentielle et radiocristallographie. Synthese d'une nouvelle serie de composes de formule tlln::(3)f::(10) et caracterisation cristallographique. Etude de proprietes optiques de ces materiaux, le transfert gd**(3+)->eu**(2+) etant envisage pour optimiser l'emission de raie uv 4f**(7)->4f**(7) de l'ion eu**(2+) dans les varietes cubique et hexagonale de rbgd::(3)f::(10). Mise en evidence des deux sites cristallographiques qu'occupe gd par analyse de la fluorescence des niveaux **(6)p::(j) de l'ion gd**(3+) dans la variete hexagonale
49
Jia, Jianjun, i 賈建軍. "The phase-resolved spectra of the crab pulsar". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B36379918.
Pełny tekst źródła
50
Jia, Jianjun. "The phase-resolved spectra of the crab pulsar". Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B36379918.
Pełny tekst źródła