Dissertations / Theses on the topic 'Thermic and spectroscopic technique'
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Natarajan, Shweta. "Thermal metrology techniques for ultraviolet light emitting diodes." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45891.
Full textAppadoo, Dominique R. T. (Dominique Rupert Thierry) 1964. "Spectral simplification techniques for high resolution fourier transform spectroscopic studies." Monash University, School of Chemistry, 2002. http://arrow.monash.edu.au/hdl/1959.1/7746.
Full textPiskorz, Danielle, Björn Benneke, Nathan R. Crockett, Alexandra C. Lockwood, Geoffrey A. Blake, Travis S. Barman, Chad F. Bender, John S. Carr, and John A. Johnson. "Detection of Water Vapor in the Thermal Spectrum of the Non-transiting Hot Jupiter Upsilon Andromedae b." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/625300.
Full textPiskorz, Danielle, Björn Benneke, Nathan R. Crockett, Alexandra C. Lockwood, Geoffrey A. Blake, Travis S. Barman, Chad F. Bender, et al. "EVIDENCE FOR THE DIRECT DETECTION OF THE THERMAL SPECTRUM OF THE NON-TRANSITING HOT GAS GIANT HD 88133 b." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622450.
Full textGrisedale, Louise Clare. "The Development of Thermal and Spectroscopic Characterisation Techniques for the Study of Amorphous Pharmaceutical Materials." Thesis, University of East Anglia, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.514322.
Full textSchueler, Robert M. "Terahertz Spectroscopic Breath Analysis as a Viable Analytical Chemical Sensing Technique." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1464170300.
Full textSmith, Paul. "Sharp Polarimetric Eyes: More Trees than Forest?" MDPI AG, 2016. http://hdl.handle.net/10150/621985.
Full textVenumuddala, Hareesha Reddy. "Study of Drug Delivery Behavior Through Biomembranes Using Thermal And Bioanalytical Techniques." Cleveland State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=csu1295472144.
Full textKolbe, G. "Three level spectroscopic technique applied to collision rate and line shape determination in a plasma." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37746.
Full textBostrom, Gregory A. "Development of a Portable Cavity Ring-Down Spectroscopic Technique for Measuring Stable Isotopes in Atmospheric Methane." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/51.
Full textChin, Yuan-Tung. "Studies of passivation of iron and its breakdown by chloride ions using in situ spectroscopic ellipsometric technique." Case Western Reserve University School of Graduate Studies / OhioLINK, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=case1054563395.
Full textBudhavaram, Naresh Kumar. "Facile protein and amino acid substitution reactions and their characterization using thermal, mechanical and optical techniques." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/40340.
Full textPh. D.
Stefansson, Gudmundur, Frederick Hearty, Paul Robertson, Suvrath Mahadevan, Tyler Anderson, Eric Levi, Chad Bender, et al. "A VERSATILE TECHNIQUE TO ENABLE SUB-MILLI-KELVIN INSTRUMENT STABILITY FOR PRECISE RADIAL VELOCITY MEASUREMENTS: TESTS WITH THE HABITABLE-ZONE PLANET FINDER." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622681.
Full textLine, Michael R., Kevin B. Stevenson, Jacob Bean, Jean-Michel Desert, Jonathan J. Fortney, Laura Kreidberg, Nikku Madhusudhan, Adam P. Showman, and Hannah Diamond-Lowe. "NO THERMAL INVERSION AND A SOLAR WATER ABUNDANCE FOR THE HOT JUPITER HD 209458B FROM HST /WFC3 SPECTROSCOPY." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622434.
Full textBenevides, Ferreira José Flavio. "La mise au point de méthodes thermiques et spectrométriques pour la caractérisation des catalyseurs pour le stockage de CO2." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00858419.
Full textScholey, Catherine Louise. "A spectroscopic study of doubly-odd N=77 isotones near the proton dripline utilising the recoil-isomer tagging technique." Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269565.
Full textPINTO, GIULIA. "Towards a DNA-based biosensor: a multi-technique study for sequence recognition." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1077811.
Full textLopez-Calvo, Alfredo Manzanares Carlos E. "Vibrational spectroscopy in cryogenic solutions application of thermal lensing and Fourier transform techniques to the study of molecular C-H overtone transitions /." Waco, Tex. : Baylor University, 2006. http://hdl.handle.net/2104/4873.
Full textVilaplana, Francisco. "Modelling the degradation processes in high-impact polystyrene during the first use and subsequent recycling." Licentiate thesis, Stockholm : Institutionen för fiber- och polymerteknologi, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4407.
Full textSanoria, Abhishek [Verfasser], Matthias [Akademischer Betreuer] Rehahn, and Markus [Akademischer Betreuer] Busch. "Developing Raman microscopy as a routine spectroscopic technique for morphology and microstructure characterization of plastics / Abhishek Sanoria ; Matthias Rehahn, Markus Busch." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2016. http://d-nb.info/1122286317/34.
Full textANTONIUCCI, SIMONE. "Accretion properties of embedded low mass protostars." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2008. http://hdl.handle.net/2108/703.
Full textI present a work aiming at studying the accretion properties low mass embedded protostars making use of two observational techniques: near IR high resolution spectroscopy and inteferometry. Through the analysis of VLT/ISAAC near infrared spectra (R = 10000) of a sample of six Class I protostars, I have derived the accretion luminosity and mass accretion rates of the objects, using either the luminosity of Hi lines or determining the stellar properties from detection of the photospheric absorption lines. Only two objects show accretion-dominated luminosities, while in the other sources accretion accounts for only a smal fraction of the total luminosity, in spite of what is commonly expected for Class I stars in the main accretion phase. These findings therefore indicate a scenario where most Class I objects are more evolved than expected and have actually already acquired most of their mass. For sources displaying well developed jet-like structures, the ratio between mass loss (derived from spectral measurements on the jet) and mass accretion rates has been computed; the inferred ratios span (considering the large uncertainties) in the range 5%-200%, to be compared with a 10% value from theoretical models. VLTI/AMBER observations have been analysed in the second part of the work with the aim of measuring the size of the Hi line emission region in the young source Z CMa, thus discriminating between an accretion or wind origin for such emission lines, often used as a tracer for accretion. A simple model of the source has been developed to derive the expected visibility curves needed to plan the observations and interpret them. Unfortunately, the very low signal-to-noise ratio characterising the data, most probably due to technical problems during observations at the VLTI, allows only a tentative interpretation of the measurements, which however tends to indicate a wind origin of the emission. Nevertheless, the methods adopted for the reduction of the AMBER data have led to the development of a reduction procedure able to filter out spurious signals from the detector that heavily bias this kind of very low flux data. This procedure will be soon implemented in the official data reduction software of the instrument.
Ehlers, Patrick. "Further development of NICE-OHMS : – an ultra-sensitive frequency-modulated cavity-enhanced laser-based spectroscopic technique for detection of molecules in gas phase." Doctoral thesis, Umeå universitet, Institutionen för fysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-92510.
Full textBrusimmun kavitetsförstärkt optisk-heterodyndetekterad molekylärspektroskopi (NICE-OHMS) är en laser-baserad spektroskopisk teknik som förenar frekvensmodulation (för reducring av 1/f-brus genom detektion vid en hög frekvens) och kavitetsförstärkning (KF, för en förlängning av den optiska väglangden) på ett unikt sätt. Korrekt realiserad uppvisar tekniken en inneboende immunitet mot omvandling av frekvensbrus till intensitetsbrus som många andra KF-tekniker är begränsade av. Allt detta ger tekniken en exceptionellt hög känslighet för molekyldetektion. Ursprungligen utvecklad för frekvensstandardändamål i slutet av 1990, har den sedan dess utvecklats för molekylspektroskopi och spårgasdetektering. Denna avhandling fokuserar på vidareutvecklingen av NICE-OHMS mot en tillämpbar, ultrakänslig detektionsteknik. Ett antal koncept har adresserats. Några av dessa är: i) Detektionskänsligheten hos fiberlaserbaserad NICE-OHMS har förbättrats till 10-12 cm-1 området, vilket för detektion av C2H2 i gasfas motsvarar några få ppt (parts per biljon, 1:1012), genom att förbättra låsningen av lasern till en kavitetsmod med hjälp av en akustooptisk modulator. ii) Det har demonstrerats att NICE-OHMS kan realiseras mer kompakt med hjälp av en fiber-kopplad optisk cirkulator. iii) En systematisk och grundlig utredning av de experimentella förhållanden som ger maximala signaler, betecknade de optimala förhållanden, t.ex. modulering och demodulering och kavitetslängden, har utförts. Som ett led i detta har ett uttryck för NICE-OHMS linjeform bortom den konventionella triplett formalismen föreslagits och verifierats. iv) För att bredda tillämpbarheten av NICE-OHMS för detektering av tryckbreddade signaler har även en instrumentering baserad på en distribuerad-återkopplad (eng. distributed feedback, DFB) laser realiserats. v) I detta område kan inte Voigt profilen modellera signalen med den noggrannhet som krävs för en korrekt bedömning av analytkoncentrationer. Därför visar avhandlingen de första implementeringarna i NICE-OHMS av linjeprofiler som inkluderar Dicke avsmalning (eng. Dicke narrowing) och hastighetsberoende effekter (eng. speed-dependent effects). Emedan sådana profiler är välkända för absorption, fanns det inga uttryck för deras dispersiva motparter. Sådana uttryck har därför härletts och validerats av medföljande experiment. vi) Tillämpbarheten av tekniken för detektion av atomer, NICE-AAS, har diskuterats och förutspåtts.
Ytterligare forskningsfinansiär: Kempestiftelserna
Mialle, Sébastien. "Développements analytiques en spectrométrie de masse à thermo-ionisation pour l'analyse isotopique de faibles quantités." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1507/.
Full textIn the framework of the French transmutation project of nuclear wastes, experiments consisted in the irradiation in a fast neutron reactor of few milligrams of isotopically enriched powders. Hence, the isotopic analysis of very small amount of irradiation products is one of the main issues. The aim of this study was to achieve analytical developments in thermal ionization mass spectrometry in order to accurately analyze these samples. Several axes were studied including the new total evaporation method, deposition techniques, electron multiplier potentialities and comparison between different isotope measurement techniques. Results showed that it was possible to drastically decrease the amounts needed for analysis, especially with Eu and Nd, while maintaining an uncertainty level in agreement with the project requirements
Lakehal, Massil. "Out of Equilibrium Lattice Dynamics in Pump Probe Setups." Thesis, Université de Paris (2019-....), 2020. http://www.theses.fr/2020UNIP7039.
Full textThe study of the out of equilibrium dynamics of strongly correlated systems, using ultrafast pulses, uncovered a plethora of phenomena with no analog in equilibrium physics. In this thesis, we theoretically investigate the out of equilibrium dynamics of the lattice degrees of freedom and their signature in pump-probe spectroscopy. We develop a Hamiltonian-based microscopic description of laser pump induced displacive coherent phonons. The theory captures the feedback of the phonon excitation upon the electronic fluid, which is missing in the state-of-the-art phenomenological formulation. We show that this feedback leads to chirping at short timescales, even if the phonon motion is harmonic. At long times, this feedback appears as a finite phase in the oscillatory signal. We apply the theory to BaFe2As2, explain the origin of the phase in the oscillatory signal reported in recent experiments, and we predict that the system will exhibit redshifted chirping at larger fluence. Our theory also opens the possibility to extract equilibrium information from coherent phonon dynamics. Another interesting phenomenon that have been reported in pump-probe spectroscopy is the oscillation of the lattice fluctuations at double phonon frequency. These oscillations are invariably interpreted as a signature of macroscopic squeezed phonon states. In this work, we identify other mechanisms of double phonon frequency oscillations that do not involve squeezing. We show that a pump induced temperature quench of the bath, to which the phonon is coupled to, or exciting a coherent phonon for which cubic anharmonicity is allowed by symmetry can also produce such oscillations in noise spectroscopy without squeezing the phonon state. We conclude that, in contrast with what is commonly believed, double phonon frequency oscillations in noise spectroscopy are not necessarily a signature of macroscopic phonon squeezing. We point out what can be a reliable criterion to identify a squeezed phonon using pump-probe spectroscopy
Lindgren, Sara. "Metallicity determination of M dwarfs." Doctoral thesis, Uppsala universitet, Observationell astrofysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-332102.
Full textIbrahim, Mohamed Asim Yousif. "Co-processing of drugs and co-crystal formers and its effect on pharmaceutical dosage-form performance : co-crystallization of urea/2-methoxybenzamide, caffeine/malonic acid, caffeine/oxalic acid and theophylline/malonic acid systems : solid-state characterization including imaging, thermal, X-ray and Raman spectroscopic techniques with subsequent evaluation of tableting behaviour." Thesis, University of Bradford, 2008. http://hdl.handle.net/10454/12760.
Full textIbrahim, Mohamed Asim Y. "Co-processing of drugs and co-crystal formers and its effect on pharmaceutical dosage-form performance. Co-crystallization of urea/ 2-methoxybenzamide, caffeine/ malonic acid, caffeine/ oxalic acid and theophylline/ malonic acid systems: Solid-state characterization including imaging, thermal, X-ray and Raman spectroscopic techniques with subsequent evaluation of tableting behaviour." Thesis, University of Bradford, 2008. http://hdl.handle.net/10454/12760.
Full textIslamic University of Omdurman and the Ministry of Higher Education in Sudan
VASSALLO, OSCAR. "Characterization of human topoisomerase IB N-terminal domain and effect of cEPA on the activity of human and L. Donovani Topoisomerase IB." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/202337.
Full textDNA topoisomerases are enzymes that catalyze the relaxation of supercoiled DNA during important processes including DNA replication, transcription, recombination and chromosome segregation. In this work I have investigated the structural properties of the N-terminal domain of the human enzyme and I have compared the effect of conjugated eicosapentaenoic acid (cEPA) on the activity of human and L. donovani topoisomerase. The 3D structure of the human enzyme has been solved in absence of the N-terminal domain and so nothing is known on its structural feature. In this thesis, the N-terminal domain of human topoisomerase IB has been expressed, purified and characterized by spectroscopic techniques. CD spectra as a function of concentration and pH indicate that the domain does not possess any defined secondary structure. The protein is probably in a natively unfolded state since its denaturation curve is indicative of a non-cooperative transition. Evidence of a partially folded structure comes from the fluorescence spectrum of ANS, whose intensity increase in presence of the domain. Indication of a partial structural arrangement of the domain comes also from the endogenous fluorescence of tryptophans that is centred at 350 nm in the native and shifts to 354 nm in the fully denaturated protein. Interestingly despite the poor degree of structural organization, as also confirmed by a predictive approach, the domain efficiently binds DNA, suggesting that the absence of a defined 3D structure has a functional meaning that permits the domain to be available for the interaction with different molecular partners. Human topoisomerase has been shown to be inhibited by several compounds and among these the best characterized one is camptothecin that, being an efficient stabilizer of the topoisomerase cleavable complex, is widely used as antitumor agent. Conjugated eicosapentaenoic acid (cEPA) has been recently found to have antitumor effects, ascribed to its ability to inhibit DNA topoisomerases and DNA polymerases. Here it is shown that cEPA inhibits the catalytic activity of human topoisomerase I, but unlike camptothecin it does not stabilize the cleavable complex, indicating a different mechanism of action. cEPA inhibits topoisomerase by impeding the catalytic cleavage of the DNA substrate as demonstrated using specific oligonucleotide substrates, and prevents the stabilization of the cleavable complex by camptothecin. Preincubation of the inhibitor with the enzyme is required to obtain complete inhibition. Molecular docking simulations indicate that the preferred cEPA binding site is proximal to the active site with the carboxylic group strongly interacting with the positively charged K443 and K587. Taken together the results indicate that cEPA does not prevent DNA binding but inhibits DNA cleavage, binding in a region close to the topoisomerase active site. The effect of cEPA on L. donovani topoisomerase has been also investigated showing an inhibitory efficiency higher than that displayed for the corresponding human enzyme. Moreover cEPA shows a strong antiprotozoal activity against L. donovani promastigotes ( EC50= 22.7 μg/ml) whilst it has no effect against murine macrophages ( IC50 > 600 μg/ml). Taken together the results indicate that L. donovani topoisomerase I can be considered an interesting molecular target and that conjugated eicosapentaenoic acid can be taken in consideration as a possible lead compound against leishmaniasis.
Carbol, Ladislav. "Měření akustických vlastností stavebních materiálů pomocí pseudonáhodné sekvence." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-355599.
Full textJunige, Marcel. "Entwicklung und Charakterisierung eines Prozesses zur thermischen Atomlagenabscheidung von Ruthenium mit in-situ Messtechnik." Master's thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-65342.
Full textRuthenium and its conductive dioxide are promising candidates as electrodes in MIM (metal-insulator-metal) capacitors with high-k dielectrics of next generation DRAM (dynamic random access memory) devices, as metal-gate electrodes in pMOS-Transistors with high-k dielectrics, and as seed layer for direct electrochemical plating of copper interconnects. ALD (atomic layer deposition) grows material layers with less than a tenth of a nanometer thickness, pulsing gaseous reactants alternately into the reaction chamber, separated by purging pulses. Hence, every cyclic recurrence of ideally self-limiting gas-solid reactions deposits a fixed material amount, until the desired film thickness is achieved. So, the surface’s chemical composition changes through material deposition during ALD, observable by in-situ SE (spectroscopic ellipsometry). Ellipsometry measures the polarization state’s change in amplitude and phase, reflecting an incident light beam from and/ or transmitting it through a (film covered) surface. The ellipsometric data can be directly related to optical material parameters and are thus physically interpretable – or they are translated into one-dimensional structural values, like film thickness. In this work, ruthenium and ruthenium dioxide films were grown from ECPR, [(ethylcyclopentadienyl)(pyrrolyl)ruthenium(II)], and molecular oxygen. Reaction mechanisms during the ALD of ruthenium and ruthenium dioxide were studied on the as-deposited film surface by in-situ SE, on-site QMS (quadrupole mass spectrometry), as well as XPS (x-ray photoelectron spectroscopy) without vacuum break. Additionally, film growth experiments were performed on the as-deposited film and the initial substrate surface by in-situ and real-time SE, varying the process parameters: reactant doses, purging times, substrate temperature and total pressure
Eiras, Fernández Jesús Nuño. "Studies on nonlinear mechanical wave behavior to characterize cement based materials and its durability." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/71439.
Full text[ES] El ensayo de determinación de las frecuencias de resonancia ha sido tradicionalmente empleado para determinar la integridad mecánica de testigos de hormigón, en la evaluación de la conformidad de mezclas de hormigón en diversos ensayos de durabilidad, y en la terminación de propiedades constitutivas como son el módulo elástico y el factor de amortiguamiento. Esta técnica no destructiva ha sido ampliamente apelada para la evaluación de las propiedades mecánicas en todo tipo de ensayos de durabilidad. La evolución del daño es comúnmente evaluada a partir de la reducción del módulo dinámico, producido como resultado de cualquier proceso de fisuración. Sin embargo, el comportamiento mecánico del hormigón es intrínsecamente no lineal y presenta histéresis. Como resultado de un comportamiento tensión-deformación con histéresis, el módulo elástico depende de la deformación. En ensayos dinámicos, la no linealidad del material se manifiesta por una disminución de las frecuencias de resonancia, la cual es inversamente proporcional a la amplitud de excitación. Este fenómeno es normalmente denominado como dinámica rápida. Una vez la excitación cesa, el material experimenta un proceso de relajación por el cual, el módulo elástico es restaurado a aquel en situación de reposo. Este fenómeno es denominado como dinámica lenta. Estos fenómenos ¿dinámicas rápida y lenta¿ encuentran su origen en la fricción interna del material. Por tanto, en materiales basados en cemento, la presencia de microfisuras y las interfaces entre sus constituyentes juegan un rol importante en la no linealidad mecánica del material. En el contexto de evaluación de la durabilidad del hormigón, la evolución del daño está basada en el incremento de histéresis, como resultado de cualquier proceso de fisuración. En esta tesis se investigan tres técnicas diferentes las cuales utilizan el impacto como medio de excitación de las frecuencias de resonancia. La primera técnica consiste en determinar las frecuencias de resonancia a diferentes energías de impacto. La técnica es denominada en inglés: Nonlinear Impact Resonant Acoustic Spectroscopy (NIRAS). Ésta consiste en relacionar el detrimento que el material experimenta en sus frecuencias de resonancia, con el aumento de la amplitud de la excitación. La segunda técnica consiste en investigar el comportamiento no lineal mediante el análisis de la señal correspondiente a un solo impacto. Ésta consiste en determinar las propiedades instantáneas de frecuencia, atenuación y amplitud. Esta técnica se denomina, en inglés, Nonlinear Single Impact Resonant Acoustic Spectroscopy (NSIRAS). Se proponen dos técnicas de extracción del comportamiento no lineal mediante el análisis de las variaciones instantáneas de frecuencia y atenuación. La primera técnica consiste en la discretización de la variación de la frecuencia con el tiempo, mediante un análisis basado en Short-Time Fourier Transform (STFT). La segunda técnica consiste en un ajuste por mínimos cuadrados de las señales de vibración a un modelo que considera las variaciones de frecuencia y atenuación con el tiempo. La tercera técnica empleada en esta tesis puede ser empleada para la evaluación de estructuras in situ. La técnica se trata de un ensayo acusto-elástico en régimen dinámico. En inglés Dynamic Acousto-Elastic Test (DAET). Las variaciones del módulo elástico obtenidas mediante los métodos NIRAS y NSIRAS proporcionan un comportamiento promedio y no permiten derivar las variaciones del módulo elástico en un solo ciclo de vibración. Actualmente, la técnica DAET es la única que permite investigar todo el rango de fenómenos no lineales en el material. Por otra parte, a diferencia de otras técnicas DAET, en este estudio se emplea como contraste una onda continua. El uso de una onda continua permite investigar las variaciones relativas del módulo elástico, para una señal transito
[CAT] L'assaig de determinació de les freqüències de ressonància ha sigut tradicionalment empleat per a determinar la integritat mecànica de testimonis de formigó, en l'avaluació de la conformitat de mescles de formigó en diversos assajos de durabilitat, i en la terminació de propietats constitutives com són el mòdul elàstic i el factor d'amortiment. Esta tècnica no destructiva ha sigut àmpliament apel·lada per a l'avaluació de les propietats mecàniques en tot tipus d'assajos de durabilitat. L'evolució del dany és comunament avaluada a partir de la reducció del mòdul dinàmic, produït com resultat de qualsevol procés de fisuración. No obstant això, el comportament mecànic del formigó és intrínsecament no lineal i presenta histèresi. Com resultat d'un comportament tensió-deformació amb histèresi, el mòdul elàstic depén de la deformació. En assajos dinàmics, la no linealitat del material es manifesta per una disminució de les freqüències de ressonància, la qual és inversament proporcional a l'amplitud d'excitació. Este fenomen és normalment denominat com a dinàmica ràpida. Una vegada l'excitació cessa, el material experimenta un procés de relaxació pel qual, el mòdul elàstic és restaurat a aquell en situació de repòs. Este fenomen és denominat com a dinàmica lenta. Estos fenòmens --dinámicas ràpida i lenta troben el seu origen en la fricció interna del material. Per tant, en materials basats en ciment, la presència de microfissures i les interfícies entre els seus constituents juguen un rol important en la no linealitat mecànica del material. En el context d'avaluació de la durabilitat del formigó, l'evolució del dany està basada en l'increment d'histèresi, com resultat de qualsevol procés de fisuración. En esta tesi s'investiguen tres tècniques diferents les quals utilitzen l'impacte com a mitjà d'excitació de les freqüències de ressonància. La primera tècnica consistix a determinar les freqüències de ressonància a diferents energies d'impacte. La tècnica és denominada en anglés: Nonlinear Impact Resonant Acoustic Spectroscopy (NIRAS). Esta consistix a relacionar el detriment que el material experimenta en les seues freqüències de ressonància, amb l'augment de l'amplitud de l'excitació. La segona tècnica consistix a investigar el comportament no lineal per mitjà de l'anàlisi del senyal corresponent a un sol impacte. Esta consistix a determinar les propietats instantànies de freqüència, atenuació i amplitud. Esta tècnica es denomina, en anglés, Nonlinear Single Impact Resonant Acoustic Spectroscopy (NSIRAS). Es proposen dos tècniques d'extracció del comportament no lineal per mitjà de l'anàlisi de les variacions instantànies de freqüència i atenuació. La primera tècnica consistix en la discretización de la variació de la freqüència amb el temps, per mitjà d'una anàlisi basat en Short-Time Fourier Transform (STFT). La segona tècnica consistix en un ajust per mínims quadrats dels senyals de vibració a un model que considera les variacions de freqüència i atenuació amb el temps. La tercera tècnica empleada en esta tesi pot ser empleada per a l'avaluació d'estructures in situ. La tècnica es tracta d'un assaig acusto-elástico en règim dinàmic. En anglés Dynamic Acousto-Elastic Test (DAET). Les variacions del mòdul elàstic obtingudes per mitjà dels mètodes NIRAS i NSIRAS proporcionen un comportament mitjà i no permeten derivar les variacions del mòdul elàstic en un sol cicle de vibració. Actualment, la tècnica DAET és l'única que permet investigar tot el rang de fenòmens no lineals en el material. D'altra banda, a diferència d'altres tècniques DAET, en este estudi s'empra com contrast una ona contínua. L'ús d'una ona contínua permet investigar les variacions relatives del mòdul elàstic, per a un senyal transitori. A més, permet la inspecció d'elements per mitjà de l'accés per una sola cara.
Eiras Fernández, JN. (2016). Studies on nonlinear mechanical wave behavior to characterize cement based materials and its durability [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/71439
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Premiado
MASTROLONARDO, GIOVANNI. "The impact of wildfires on the abundance, composition and recalcitrance of soil organic matter." Doctoral thesis, 2013. http://hdl.handle.net/2158/802673.
Full textHsu, Sheng-Hsien, and 許聖賢. "Probing the Thin Film via Terahertz Spectroscopic Technique." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/85880935691781097010.
Full text國立臺灣海洋大學
光電科學研究所
93
We have determined the complex conductivity and the refractive indices of GaN and InGaN/GaN MQWs LED by terahertz time-domain spectroscopy. Frequency dependent electron dynamics, power absorption and dispersion are obtained over the frequency range from 0.1 to 3.0THz. The index of refraction of the GaN film varies from 10.0 to 2.6. The power absorption of the GaN film varies from 62mm-1 to 230mm-1.The real conductivity of the GaN film varies from 19.2/Ωcm to 13.4/Ωcm. The transmission measurements of the GaN film are fit by simple Drude model. We obtain the plasma frequency and the carrier damping rate of the GaN film are 11.64THz and 3.92THz, respectively. The index of refraction of the InGaN/GaN MQWs LED varies from 11.0 to 2.9. The power absorption of the InGaN/GaN MQWs LED varies from 65mm-1 to 252mm-1. The real conductivity of the InGaN/GaN MQWs LED varies from 23.2/Ωcm to 12.4/Ωcm. The transmission measurements of the InGaN/GaN MQWs LED are fit by simple Drude model. We obtain the plasma frequency and the carrier damping rate of the InGaN/GaN MQWs LED are 11.31THz and 3.08THz, respectively.
徐國謙. "Application of THz Time-domain Spectroscopic Technique in Powdered Samples." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/36433274888217928299.
Full text國立清華大學
物理學系
91
We use mode-locked Ti:Sapphire Laser, wavelength 800nm, after being chirped pulse amplification and splitted, the power of per pulse is 12.8GW, pulse width 130fs, to pump insulated GaAs witch biased by DC voltage, and generate THz pulse with pulse width 5ps.We can get the time-domain spectroscopy of THz by electro-optic sampling. We let the THz signal pass through Ba2(Ti1-xSnx)9O20 x=0,0.024 sintered 4hrs and calculate the dielectric constant by effective-medium theory, and we compare the result with the dielectric constant at microwave range (4GHz). After that, we get several conclusions:1.The dielectric constants of the powdered samples are similar to sintered samples (about 39.5 and 38). 2.At the rage 0.1THz~0.6THz (besides 0.2TH), we also get the result that the Q values of x=0.024 are higher. 3.The power absorption coefficients of x=0 and 0.024 are different obviously, this may be caused by sintered or not. Application of THz Time-domain Spectroscopic Technique in Powdered Samples
蓋惠珍. "Development of autofluorescence spectroscopic diagnosis technique for the precancer of cervical tissue." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/92129316713374395460.
Full textFu, Yao. "Implementation of Wavelet Encoding Spectroscopic Imaging Technique on a 3 Tesla Whole Body MR Scanner." 2010. http://hdl.handle.net/1993/3972.
Full textSanoria, Abhishek. "Developing Raman microscopy as a routine spectroscopic technique for morphology and microstructure characterization of plastics." Phd thesis, 2016. https://tuprints.ulb.tu-darmstadt.de/5864/1/PhD%20thesis_Abhishek%20Sanoria.pdf.
Full textLIN, YI-CANG, and 林怡蒼. "Study on The Tautomerization of 1-Aryldiazo-2-naphthalenol Derivatives by Using The Spectroscopic Technique." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/85644351672906327063.
Full text靜宜大學
應用化學系
104
The substituent effect on azo-hydrazone tautomerization of 1-aryldiazo-2-naphthalenol is studied by means of NMR and MS analysis. Among the 13C chemical shifts, the C(2) of this series compound is the most sensitive to the variation in the nature of substituent on the phenyl ring. Therefore, the variation in the chemical shifts of C(2) is used to probe the substituent effect by using the substituent chemical shifts and free energy vs. Hammett’s constant (σ+). Both methods give a negative correlation slope, which are ρ=-8.74 and ρ=-1.38 , indicating the electron-withdrawing groups favor the hydrazone tautomer form. The effect on the chemical shifts of C(2) of 1-phenyldiazo-2-naphthalenol in ten solvents can be classified as the solvent with a proton-donor, proton-acceptor and arenes system. The substituent with electron-donating character is more sensitive to the nature of solvent and it favors the azo form. Free energy obtained from the dynamic NMR technique indicates the tautomerization favors the hydrazone-form for the substituent with electron-withdrawing character. The relaxation time of carbon are slight affected by the size of substituents. In the viscosity study, an inverse-law relationship between relaxation times and viscosity was observed. An electron-ionization (EI) mass spectra of a series of 1-aryldiazo-2-naphthalenol was obtained for studying the substituent effect on the fragmentation. The correlation between the ratio, molecular ion and fragment ion, and Hammett’s constants is applied to examine the effect of the substituent on the fragmentation. The negative correction between the ratio, Imolecular ion/(I171amu + I143amu + I115amu), and Hammett’s constants, which is ρ=-0.778, indicates an electron-withdrawing group destabilized the molecular ion. An unusual long-range hydrogen transfer demonstrates an important role in the fragmentation process.
"Integrating Analytical and Remote Sensing Techniques to Investigate the Petrology of Planetary Surfaces." Doctoral diss., 2018. http://hdl.handle.net/2286/R.I.49367.
Full textDissertation/Thesis
Doctoral Dissertation Geological Sciences 2018
Ryu, Suk-Kyu. "Thermo-mechanical stress analysis and interfacial reliabiity for through-silicon vias in three-dimensional interconnect structures." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-12-4580.
Full texttext
MORDINI, SABRINA. "Galaxy evolution studies with the SPICA telescope." Doctoral thesis, 2021. http://hdl.handle.net/11573/1618149.
Full textM, Manseau Patrick. "Recherche et analyse d'étoiles naines blanches chimiquement stratiées dans le Sloan Digital Sky Survey." Thèse, 2016. http://hdl.handle.net/1866/16201.
Full textWe present a detailed research and analysis of chemically stratified hybrid white dwarf stars in the Sloan Digital Sky Survey (SDSS). Only one stratified star, PG 1305-017, was known before our analysis. The main objective is to confirm the existence of several new stratified stars. To do so, we initially had to develop a new generation of model atmospheres from those of Bergeron et al. (1991) and Tremblay & Bergeron (2009). We added the opacity of all the helium lines and the necessary calculations to account for the chemical stratification of the atmosphere, where a thin hydrogen layer floats in diffusive equilibrium on top of a more massive helium layer. In parallel, we also calculated a grid of standard models, which are chemically homogeneous. Then, we selected hot white dwarfs (Teff > 30,000 K) with a hybrid spectral type (traces of helium and hydrogen) from the ~38,000 white dwarfs listed in the SDSS. A total of 52 spectra were retained in our final sample. The spectroscopic technique, i.e. the fit of model spectra to an observed spectrum, was applied to all stars in our sample. Thereby, we have measured the effective temperature, the surface gravity and the chemical composition of these stars. By simultaneously fitting stratified and homogeneous models, we have also been able to determine if the stars were stratified or not. We identify 14 stratified white dwarfs. From these results, we draw several conclusions on the physical processes explaining the presence of helium in the atmosphere.
Legodi, Malebogo Andries. "Raman spectroscopy applied to iron oxide pigments from waste materials and earthenware archaeological objects." Thesis, 2008. http://upetd.up.ac.za/thesis/available/etd-06062008-113000.
Full textOn title page: Submitted in partial fulfilment of the degree Philosophiae Doctor in Chemistry in the faculty of Natural and Agricultural Sciences of the University of Pretoria. Includes bibliographical index.
Akbari, Khorami Hamed. "Hydrogen peroxide sensing with prussian blue-based fiber-optic sensors." Thesis, 2016. http://hdl.handle.net/1828/7585.
Full textGraduate
0794
0548
0485
hakbarik@uvic.ca
Genest-Beaulieu, Cynthia. "Analyse et modélisation d’étoiles naines blanches de type DB dans le Sloan Digital Sky Survey et le relevé Gaia." Thèse, 2019. http://hdl.handle.net/1866/22672.
Full textDarveau-Bernier, Antoine. "Une exploitation additionnelle du catalogue de mouvements propres LSPM pour l'étude statistique des étoiles naines blanches." Thèse, 2016. http://hdl.handle.net/1866/18799.
Full textWe present an additional exploitation of the Lépine \& Shara Proper Motion catalog (LSPM) divided in two main parts: a follow up and some improvements on the census or northern white dwarfs within 40 pc of the Sun and a study of the SDSS white dwarfs component in the LSPM survey. The former consists in the use of criteria previously established in order to create a list of white dwarf candidates with an associated priority. The priority order has been enriched and one of the criteria has been slightly modified. We then use a non-linear least square method to the observed magnitudes in each available photometric system simultaneously in order to determine the atmospheric parameters and, in particular, the distance of each white dwarf candidate. This approach allows a second criteria to be applied on our sample based on the goodness of the fit. This will lead us to the identification of 31 new white dwarfs, from which 11 are likely to remain within 40 pc of the Sun. A new list of 340 candidates has also been established for eventual observations. The latter consists in the use of all the objects from the 7th data release of the SDSS that have a counterpart in the LSPM catalog to elaborate a statistical study of white dwarfs, in this case by calculating the white dwarf luminosity function. To do so, one of the same criterion mentioned above will be used to make a first selection of presumed white dwarfs. Afterwards, the distance will be determined by the same least-square method, but without any restriction on the distance. To balance the effect due to the sensibility in magnitude of the survey, we used a ponderation method based on the maximum observable volume (1/v_max). However, other factors come to affect our results and the last part of this work concentrates on their identification.