Dissertations / Theses on the topic 'In-situ temperature'
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1
borgonovo, cecilia. "Aluminum Nano-composites for Elevated Temperature Applications." Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-theses/962.
Full textAbstract:
"Conventional manufacturing methods are sub-optimal for nano-composites fabrication. Inhomogeneous dispersion of the secondary phase and scalability issues are the main issues. This work focuses on an innovative method where the reinforcement is formed in-situ in the melt. It involves the reaction of the molten aluminum with a nitrogen- bearing gas injected through the melt at around 1273 K. AlN particles are expected to form through this in situ reaction. A model has been developed to predict the amount of reinforced phase. Experiments have been carried out to confirm the feasibility of the process and the mechanism of AlN formation discussed. The detrimental effect of oxygen in the melt which hinders the nitridation reaction has been proved. The effect of process times and the addition of alloying elements (Mg and Si) have also been investigated."
2
Lee, Kok Loong. "Deformation behaviour of Cu-Cr in-situ composite." Thesis, University of Leicester, 2004. http://hdl.handle.net/2381/11077.
Full textAbstract:
With the increasing requirements for higher strength materials with high electrical conductivity, a lot of interest has been paid to develop Cu-based composites in the last 25 years. These composites have superior tensile strength, combined with good electrical conductivity, to that exhibited by pure Cu and conventional Cu alloys. To date, much of the research carried out on this composite has focused on the mechanical and electrical properties of the as processed material. However, there is a basic lack of understanding of the way in which the properties may change or degrade during service. Without this knowledge, these composites cannot be fully and safely exploited. Thus the objective of this study was to investigate the thermo-mechanical behaviour of a Cu-Cr composite, and the nature and extent of any damage mechanisms occurring within the composite over a wide range of experimental conditions. Neutron diffraction was used to investigate the deformation behaviour of the individual phases in the composite and their interaction through elastic and plastic loading at room temperature. For the composite, a fairly good agreement was observed in the phase strains predicted by the Eshelby theory and measured by neutron diffraction. In-situ tensile tests in the SEM were also performed to study the damage mechanism of the composite. Tensile and creep tests were carried out in air and in vacuum over a wide range of temperatures. To provide data for comparison with the composite material, pure Cu specimens were tested whenever possible. Creep resistance increases significantly with the introduction of Cr fibres into Cu. The higher creep rate of the composite in air than in vacuum is due to the gradual decrease of the cross-sectional area of the matrix due to increasing thickness of the oxide layer. Damage characteristics and distributions were found to be similar during tensile and creep testing.
3
Arnold, Klaus, Astrid Ziemann, and Armin Raabe. "Acoustic tomography in comparision to in-situ temperature and wind measurements." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-216523.
Full textAbstract:
Acoustic travel time tomography is presented as an experimental technique for remote monitoring of areally averaged meteorological quantities as the air temperature and the horizontal wind speed. This ground based remote sensing technique uses the nearly horizontal propagation of sound waves in the atmospheric surface layer. Here the acoustic travel time tomography was applied by measuring the travel time at defined propagation paths between several sound sources and receivers. The resulting sound speed were used to obtain estimates of the meteorological parameters. A measuring campaign was carried out at the test site in Lindenberg (DWD) to compare the acoustically derived data with conventional systems. These observations demonstrated that on one side the accuracy of the acoustic system is comparable with in-situ measurements and on the other side the temperature was particularly significant overestimated by the standard sensors, e.g. due to the radiation influenceDie Akustische Laufzeittomographie wird als ein experimentelles Verfahren zur Sondierung meteorologischer Parameter, wie z.B. der Lufttemperatur und der horizontalen Windgeschwindigkeit, vorgestellt. Dieses bodengebundene Fernerkundungsverfahren nutzt die horizontale Ausbreitung von Schallwellen in der atmosphärischen Grenzschicht. Hier wird das Verfahren der Laufzeittomographie angewendet, d.h. bei bekannter Weglänge wird die Ausbreitungszeit von ausgesendeten Schallsignalen zwischen mehreren Schallquellen und Empfängern gemessen. Die resultierenden Schallgeschwindigkeitsinformationen werden genutzt, um daraus die entsprechenden meteorologischen Parameter abzuleiten. Auf dem Gelände des Meteorologischen Observatoriums Lindenberg (DWD) wurde eine Messkampagne durchgeführt, um die akustischen Sondierungen mit konventionellen Systemen zu vergleichen. Die Auswertungen zeigen, dass einerseits die Genauigkeit der Akustischen Tomographie vergleichbar mit den konventionellen in-situ Messungen ist und andererseits, dass die Lufttemperatur aufgrund des Strahlungseinflusses bei Messungen mit den üblichen Sensoren zum Teil erheblich überschätzt wird
4
Arnold, Klaus, Astrid Ziemann, and Armin Raabe. "Acoustic tomography in comparision to in-situ temperature and wind measurements." Wissenschaftliche Mitteilungen des Leipziger Instituts für Meteorologie ; 22 = Meteorologische Arbeiten aus Leipzig ; 6 (2001), S. 60-68, 2001. https://ul.qucosa.de/id/qucosa%3A15201.
Full textAbstract:
Acoustic travel time tomography is presented as an experimental technique for remote monitoring of areally averaged meteorological quantities as the air temperature and the horizontal wind speed. This ground based remote sensing technique uses the nearly horizontal propagation of sound waves in the atmospheric surface layer. Here the acoustic travel time tomography was applied by measuring the travel time at defined propagation paths between several sound sources and
receivers. The resulting sound speed were used to obtain estimates of the meteorological parameters. A measuring campaign was carried out at the test site in Lindenberg (DWD) to compare the acoustically derived data with conventional systems. These observations demonstrated that on one side the accuracy of the acoustic system is comparable with in-situ measurements and on the other side the temperature was particularly significant overestimated by the standard sensors, e.g. due to the radiation influence.Die Akustische Laufzeittomographie wird als ein experimentelles Verfahren zur Sondierung meteorologischer Parameter, wie z.B. der Lufttemperatur und der horizontalen Windgeschwindigkeit, vorgestellt. Dieses bodengebundene Fernerkundungsverfahren nutzt die horizontale Ausbreitung von Schallwellen in der atmosphärischen Grenzschicht. Hier wird das Verfahren der Laufzeittomographie angewendet, d.h. bei bekannter Weglänge wird die Ausbreitungszeit von ausgesendeten Schallsignalen zwischen mehreren Schallquellen und Empfängern gemessen. Die resultierenden Schallgeschwindigkeitsinformationen werden genutzt, um daraus die entsprechenden meteorologischen Parameter abzuleiten. Auf dem Gelände des Meteorologischen Observatoriums Lindenberg (DWD) wurde eine Messkampagne durchgeführt, um die akustischen Sondierungen mit konventionellen Systemen zu vergleichen. Die Auswertungen zeigen, dass einerseits die Genauigkeit der Akustischen Tomographie vergleichbar mit den konventionellen in-situ Messungen ist und andererseits, dass die Lufttemperatur aufgrund des Strahlungseinflusses bei Messungen mit den üblichen Sensoren zum Teil erheblich überschätzt wird.
5
Elwood, Teri, Whit Bennett, Teh Lai, and Kelly Simmons-Potter. "In-situ comparison of thermal measurement technologies for interpretation of PV module temperature de-rating effects." SPIE-INT SOC OPTICAL ENGINEERING, 2016. http://hdl.handle.net/10150/622582.
Full textAbstract:
It is well known that the efficiency of a photovoltaic (PV) module is strongly impacted by its temperature such that higher temperatures lead to lower energy conversion efficiencies. An accurate measurement of the temperature de-rating effect, therefore, is vital to the correct interpretation of PV module performance under varied environmental conditions. The current work investigates and compares methods for performing measurements of module temperature both in the lab and in field-test environments. A comparison of several temperature measurement devices was made in order to establish the ideal sensor configuration for quantifying module operating temperature. Sensors were also placed in various locations along a string of up to eight photovoltaic modules to examine the variance in operating temperature with position in the string and within a larger array of strings.
6
Wang, Peng. "Corrosion behaviour of zirconium alloys in high temperature aqueous environment by electrochemical impedance spectroscopy." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/corrosion-behaviour-of-zirconium-alloys-in-high-temperature-aqueous-environment-by-electrochemical-impedance-spectroscopy(e1bf6a9f-c8ca-45db-8e05-14ee723886d9).html.
Full textAbstract:
The corrosion behaviour of zirconium based alloys has been primarily investigated by electrochemical impedance spectroscopy (EIS). In-situ autoclave EIS experiments were performed in simulated primary coolant conditions in order to study the high temperature water corrosion of zirconium alloys in PWRs. In-situ impedance response of the corroding material was recorded throughout first kinetic transition. A physical model of the zirconium oxide was proposed in accordance with the microstructural observation' made by SEM analysis. Electrical properties of the oxide was evaluated with equivalent circuit model (ECM) which was constructed according to the physical oxide model. Evolution of various oxide parameters obtained from ECM was analysed in accordance with the microstructure observation made by SEM. A two layer structure consists of a outer porous oxide and an inner barrier oxide, was found to be the most accurate description for the autoclave formed oxide. Supporting evidence from the SEM cross-section and surface analysis of the oxide had shown cracks and pores that were linked and connected with the environment. This observation is also confirmed by the in-situ EIS measurement which has shown porous electrode behaviour throughout the course of oxidation. The porous oxide behaviour was also confirmed by the ex-situ soaking experiment on samples with incremental exposure time. Evolution of inner barrier layer oxide thickness was found to be correlated with kinetic transition which was determined from weight gain measurement. This indicated that barrier layer maybe the oxidation rate controlling layer and its thickness maybe reduced during transition. Thus, a thinner barrier layer would resulted in a rapid corrosion of zirconium alloys. Furthermore, maintaining the barrier layer thickness maybe the possible route to improve zirconium alloy corrosion resistance.
7
Rodriguez, Jose Ramon. "Experimental and analytical study to model temperature profiles and stoichiometry in oxygen-enriched in-situ combustion." Texas A&M University, 2003. http://hdl.handle.net/1969.1/134.
Full textAbstract:
A new combustion zone analytical model has been developed in which the combustion front temperature may be calculated. The model describes in the combustion zone, the amount of fuel burned based on reaction kinetics, the fuel concentration and produced gas composition based on combustion stoichiometry, and the amount of heat generated based on a heat balance.
Six runs were performed in a 3-inch diameter, 40-inch long steel combustion tube with Jobo crude oil (9-11°API) from the Orinoco Belt in Venezuela. These runs were carried out with air containing three values of oxygen concentration, 21%, 30%, and 40%. The weight percentage of sand, clay, water, and oil in the sand mix was kept constant in all runs at 86.6%, 4.7%, 4.0%, and 4.7% respectively. Injection air rates (3 L/min) as well as the production pressure (300 psig) were kept constant in all runs.
The results indicate that the calculated combustion zone temperatures and temperature profiles are in good agreement with the experimental data, for the range of oxygen concentration in the injected air. The use of oxygen-enriched air slightly increased the combustion front temperature from 440°C in a 21 mole % O2 concentration to a maximum of 475°C for air with 40 mole % O2 concentration.
Oxygen-enriched air injection also increased the combustion front velocity from 13.4 cm/hr (for 21% oxygen) to 24.7 cm/hr (for 40% oxygen), thus reducing the start of oil production from 3.3 hours (for 21% oxygen) to 1.8 hours (for 40% oxygen). In the field, the use of oxygen-enriched air injection could translate into earlier oil production compared to with not-enriched air injection.
The new analytical model for the combustion zone developed in this study will be beneficial to future researchers in understanding the effect of oxygen-enriched in-situ combustion and its implications on the combustion front temperature and combustion front thickness.
8
Jahnke, Sebastian Ingo. "Pipeline leak detection using in-situ soil temperature and strain measurements." Diss., University of Pretoria, 2018. http://hdl.handle.net/2263/66579.
Full textAbstract:
This project investigated whether by measuring temperature and strain changes in the ground
around a pipeline a leak can be detected using fibre optic instrumentation. The concept entails
installation of an optic fibre along the length of the pipeline in the pipe trench when a new pipe
is installed. Alternatively, the possibility also exists to retrofit such a leakage detection system
by burying it near (above) existing pipes, although this has not been investigated in this project.
The success of such a leakage detection system is based on the hypothesis that the
temperature differential between the water in a pipeline and the ground around the pipe will
result in a detectable temperature change in the ground when a leak occurs. Softening of the
pipe support due to leaking water should result in strain changes in the soil immediately around
the pipe and in the pipe itself, both of which should be detectable. All three of these quantities,
i.e. ground temperature, ground strain and pipe strain can be measured using fibre optic
technology. This study is based on detecting temperature and strain changes using fibre
Bragg grating sensors (FBGS) at discrete locations along the length of a pipe.
The success of a system based on temperature measurement implies that temperature
changes caused by a leak should be distinguishable from naturally occurring temperature
cycles. Installations were therefore conducted to measure ground temperature changes to a
depth of 3m over the course of a year and comparing those to temperature changes measured
in active water mains over the same period in Pretoria. A temperature differential that always
exceeded 2°C was recorded, indicating that the system has potential to provide a means of
leak detection. A laboratory study was carried out to observe temperature changes associated with an
advancing wetting plume caused by a simulated leak using thermistors buried in fine sand.
Depending on the magnitude of the soil-water temperature differential, a rapid drop in
temperature was observed at monitoring locations during the progression of the wetting plume
(the water temperature is typically lower than the soil temperature). However, an initial shortduration
increase (spike) in temperature was consistently observed at measurement locations
upon first passage of the wetting front. It is hypothesised that this spike is caused by the
release of free surface energy upon wetting of the soil. As expected, immediately following
this spike after the passage of the wetting front, a significant and rapid change in temperature
was noted during the tests. The temperature reduction is dependent on the temperature
differential between the water and the surrounding soil and illustrated the potential of the
proposed method of leak detection (i.e. detecting leaks by observing a reduction in ground
temperature).
After the laboratory phase, a field study was conducted during which a 110 mm diameter 12
m long uPVC pipe was installed with sensor arrays consisting of both temperature and total
strain FBGS. Thermistors were used as temperature sensors as in the case of the laboratory
investigation. Strain sensors used were discrete optical strain gauges or fibre Bragg grating
sensors (FBGS). Fifty percent of the FBGS were epoxied to the pipe to measure pipe strains,
while the remaining 50% were free-floating, situated in a thin oil-filled plastic tube buried in the
corner of the pipe trench. The purpose of the epoxied FBGS was to measure pipe strain
changes, while the purpose of the free-floating FGBS was to detect temperature-induce strain
changes. During a leak, strain changes were recorded in the free-floating FBGS several times
exceeding the values expected based on the temperature changes measured by the
thermistors. In addition, very significant pipe strain changes were observed. These
observations indicate that significant ground and pipe strains occur due to wetting and
subsequent softening of the soil caused by the leak. The change in total strain and
temperature observed during a leakage event provided strong evidence that both parameters
can be used to effectively indicate the presence of a leakage event.
A complication identified in the study is that network pressure fluctuations result in significant
pipe strains which would complicate leak identification. It is therefore recommended that the
leakage detection system should comprise of an optic fibre separated from, but in close
proximity to the pipe. This study should be followed up to investigate the performance of a
leakage detection system based on distributed strain measurement and the potential of
retrofitting the proposed detection system to existing pipelines.Dissertation (MEng)--University of Pretoria, 2018.
Civil Engineering
MEng
Unrestricted
9
Brandt, Josef. "Temperature Dependent Size Exclusion Chromatography for Investigating Thermoreversibly Bonding Polymer Systems." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-207589.
Full textAbstract:
Polymers capable of thermally controlled reversible bonding reactions are promising candidates for stimuli responsive materials, as required for self-healing or drug delivery materials. In order to investigate how the dynamic reactions can be controlled, effective analytical tools are demanded that are capable of analyzing not only the polymers but can also monitor the respective bonding reactions. Herein, we employ size exclusion chromatography in a newly developed temperature dependent mode (TD SEC) for the in situ characterization of polymers that undergo retro Diels-Alder (rDA) reaction at temperatures higher than 60 °C. Monitoring the evolution of the molar mass distribution of the polymers during the rDA reaction and evaluating the data quantitatively gives detailed information about the extent of the reaction and allows elucidating structural parameters that can be used for controlling the polymers debonding behavior.
In contrast to spectroscopic techniques, TD SEC analyzes only the size of the polymers, hence the polymers do not need to fulfill any particular requirements (e.g. presence of detectable functional groups) but only need to be soluble in the TD SEC, which makes the method universally applicable. Side effects that might bias the results are minimized by using a high temperature chromatograph that allows performing the analysis in a broad temperature range (60 – 200 °C) and in different solvents. Thus, the analysis can be performed under the exact conditions that are required for the bonding reactions and an in situ image is provided.
10
Mills, Robert Jeffrey. "Abrasive Blasting with Post-Process and In-Situ Characterization." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/49680.
Full textAbstract:
Abrasive blasting is a common process for cleaning or roughening the surface of a material prior to the application of a coating. Although the process has been in practice for over 100 years, the lack of a comprehensive understanding of the complex interactions that exist with the process can still yield an inferior surface quality. Subsequently, parts can be rejected at one of many stages of the manufacturing process and/or fail unexpectedly upon deployment. The objective of this work is to evaluate the effect of selected input parameters on the characteristics of the blasted surface characteristics so that a more useful control strategy can be implemented. To characterize surface roughness, mechanical profilometry was used to collect average roughness parameter, Ra. Decreasing blast distance from 6” to 4” gave ΔRa = +0.22 µm and from 8” to 6” gave ΔRa = +0.22 µm. Increasing blast pressure from 42 psi to 60 psi decreased the Ra by 0.33 µm. Media pulsation reduced Ra by 0.56 µm and the use of new media reduced Ra by 0.47 µm. Although blasting under the same conditions and operator on different days led to ΔRa due to shorter blast times, there was no statistically significant variance in Ra attributed to blasting on different days. Conversely, a ΔRa = +0.46 µm was observed upon blasting samples with different cabinets. No significant ΔRa was found when switching between straight and Venturi nozzles or when using different operators.
Furthermore, the feasibility of fiber optic sensing technologies was investigated as potential tools to provide real time feedback to the blast machine operator in terms of substrate temperature. Decreasing the blast distance from 6” to 4” led to ΔT = +9.2 °C, while decreasing the blast angle to 45° gave ΔT= -11.6 °C for 304 stainless steel substrates. Furthermore, increasing the blast pressure from 40 psi to 50 psi gave ΔT= +15.3 °C and changing from 50 psi to 60 psi gave ΔT= +9.9 °C. The blast distance change from 8” to 6” resulted in ΔT = +9.8 °C in thin stainless steel substrate temperature. The effects of substrate thickness or shape were evaluated, giving ΔT= +7.4 °C at 8” distance, ΔT= +20.2 °C at 60 psi pressure, and ΔT= -15.2 °C at 45° blasting when comparing thin stainless steel against 304 stainless steel (thick) temperatures. No significant ΔT in means was found when going from 6” to 8” distance on 304 stainless steel, 40 psi and 60 psi blasting of thin SS, as well as angled and perpendicular blasting of thin SS. Comparing thick 304 and thin stainless steel substrates at a 6” blast distance gave no significant ΔT.Master of Science
11
Banchewski, Juri. "Transient Liquid Assisted Growth of YBCO Superconducting Films: Growth Kinetics, Physical Properties and Vortex Pinning." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/671035.
Full textAbstract:
Els superconductors d’alta temperatura (HTS) han liderat els programes d’investigació I desenvolupament durant tres dècades i actualment es troben a prop de ser integrats en aplicacions de gran escala, en forma de cintes superconductores (CCs), una arquitectura de cinta robusta i flexible que permet el creixement texturat d’aquest material fràgil. Un escull pendent per l’amplia implementació de les CCs és l’alt ratio de cost/prestació, essencialment controlat pel creixement complexa i descelerat de la capa de HTS. En aquesta tesis, vem agafar el repte de millorar el rendiment i cost dels mètodes de creixement convencionals a través del desenvolupament d’una nova tècnica de creixement que combina la deposició de solucions químiques (CSD), deposició del precursor inherentment de baix cost, amb l’alta velocitat de creixement, una aproximació de creixement de no equilibri que permet la formació d’una fase líquida transitòria (Ba-Cu-O) que condueix a la cristal·lització del producte final: Creixement Assistit per Líquid Transitori a través de CSD (TLAG-CSD).
Hem utilitzat aquest procés nou per créixer capes primes de YBa2Cu3O7-d (YBCO), un material HTS basat en cuprats de inigualables prestacions sota camps magnètics aplicats i altes temperatures. Aquestes propietats tan impressionants sols es poden assolir si el compost, elèctricament anisotròpic, exhibeix una textura biaxial i conté suficients defectes per ancorar els vòrtexs, quantificacions de flux magnètic que necessiten ser immobilitzades per obtenir conducció de corrent elèctric sense pèrdues. Per tant, no tan sols pretenem la comprensió dels fonaments del procés TLAG-CSD, sinó també promoure formes de creixement epitaxial a grans velocitats, evitant les causes de degradació del corrent, i fomentant l’enriquiment d’un paisatge adequat per l’ancoratge de vòrtexs. Per afrontar aquests reptes, hem combinat varis mètodes avançats de caracterització: Hem realitzat experiments de creixement in-situ en una instal·lació de llum sincrotró per avaluar la cinètica de creixement a diferents pressions parcial i total d’oxigen, temperatura de creixement, rampa d’escalfament, gruix de la capa HTS i composició, així com l’addició de nanopartícules (NP). La combinació dels diferents experiments s’ha resumit satisfactòriament en els anomenats diagrames de fase cinètics, una representació visual dels processos fora de l’equilibri i un roadmap per la seva utilització.
Les capes de YBCO epitaxial orientades segons l’eix c s’han estudiar minuciosament amb difracció de raigs-X, microscòpia electrònica de transmissió (TEM), experiments de transport elèctric a baixes temperatures i inducció magnètica per identificar les limitacions i oportunitats del procés. Això va incloure l’estudi de la microestructura del YBCO i les propietats elèctriques per evitar la reactivitat del líquid amb el substrat, la segregació de fases secundaries, a la vegada que asseguràvem l’eliminació del CO2 i el dopatge d’oxigen de l’estructura cristal·lina.
Finalment, hem revelat que amb el mètode TLAG-CSD es poden assolir velocitats de creixement epitaxial per sobre de 100nm/s, sobrepassant dos ordres de magnitud les tècniques convencionals utilitzades en la fabricació de CC (TFA-CSD/PLD/MOCVD). Les capes superconductores van assolir un alineament epitaxial alt dels grans (Δω<0.6º i Δφ<1º), temperatures crítiques (Tc=88-92K) i densitats de corrent competitives (Jc(77K)=2-5MA/cm2). A més, classifiquem el procés TLAG-CSD com altament versàtil per enriquir el paisatge d’ancoratge de vòrtexs, no solament a través de la capacitat de promoure una alta densitat de faltes d’apilament i grans de YBCO orientats-ab molt petits (5-10nm) en les capes de YBCO, sinó per la seva compatibilitat per formar nanocompostos amb l’addició de nanopartícules preformades.Los superconductores de alta temperatura (HTS) han liderado los programas de investigación y desarrollo durante tres décadas y actualmente se encuentran cerca de ser integrados, en aplicaciones de gran escala, en forma de cintas superconductoras (CCs), una arquitectura de cinta robusta y flexible que permite el crecimiento texturado de este material frágil. Un escollo pendiente para la amplia implementación de las CCs es el alto ratio de coste/prestación, esencialmente controlado por el crecimiento complejo y descelerado de la capa de HTS. En esta tesis, cogimos el reto de mejorar el rendimiento y coste de los métodos de crecimiento convencionales a través del desarrollo de una nueva técnica de crecimiento que combina la deposición de soluciones químicas (CSD), deposición del precursor inherentemente de bajo coste, con la alta velocidad de crecimiento, una aproximación de crecimiento de no equilibro que permite la formación de una fase líquida transitoria (Ba-Cu-O) que conduce a la cristalización del producto final: Crecimiento Asistido por Liquido Transitorio a través de CSD (TLAG-CSD). Hemos utilizado este proceso nuevo para crecer capas delgadas de YBa2Cu3O7-d (YBCO), un material HTS basado en cupratos de inigualables prestaciones bajo campos magnéticos aplicados y altas temperaturas. Estas propiedades tan impresionantes solo se pueden alcanzar si el compuesto, electrónicamente anisotrópico, exhibe una textura biaxial y contiene suficientes defectos para anclar a los vórtices. Por tanto, no solo pretendemos la comprensión de los fundamentos del proceso TLAG-CSD, sino también promover formas de crecimiento epitaxial a grandes velocidades, evitando las causas de degradación de la corriente, y fomentando el enriquecimiento de un paisaje adecuado para el anclaje de vórtices. Para afrontar estos retos, hemos combinado varios métodos avanzados de caracterización: Realizamos experimentos de crecimiento in-situ en una instalación de luz sincrotrón para evaluar la cinética de crecimiento a distintas presiones parcial y total de oxígeno, temperatura de crecimiento, rampa de calentamiento, grosor de la capa HTS y composición, así como la adición de nanopartículas (NP). La combinación de los distintos experimentos se ha resumido satisfactoriamente en los llamados diagramas de fase cinéticos, una representación visual de los procesos fuera del equilibrio y un roadmap para su utilización. Las capas de YBCO epitaxiales orientadas según el eje c se estudiaron minuciosamente con difracción de rayos-X, microscopía electrónica de transmisión (TEM), experimentos de transporte eléctrico a bajas temperaturas e inducción magnética para identificar las limitaciones y oportunidades del proceso. Ello incluyó estudiar la microstructura del YBCO y las propiedades eléctricas para evitar la reactividad del líquido con el sustrato, la segregación de fases secundarias, a la vez que asegurar la eliminación de CO2 y el dopaje de oxígeno de la estructura cristalina. Revelamos que con el método TLAG-CSD se pueden alcanzar velocidades de crecimiento epitaxial por encima de 100nm/s, sobrepasando dos órdenes de magnitud las técnicas convencionales utilizadas en la fabricación de CC (TFA-CSD/PLD/MOCVD). Las capas superconductoras alcanzaron un alineamiento epitaxial alto de los granos (Δω<0.6º y Δφ<1º), temperaturas críticas (Tc=88-92K) y densidades de corriente crítica competitivas (Jc(77K)=2-5MA/cm2). Además, clasificamos al proceso TLAG-CSD como altamente versátil para enriquecer el paisaje de anclaje de vórtices, no solo a través de la capacidad de promover una alta densidad de faltas de apilamiento y granos de YBCO orientados-ab muy pequeños (5-10nm) en las capas de YBCO, sino por su compatibilidad para formar nanocompuestos con la adición de nanopartículas preformadas.
High temperature superconductors (HTS) have been driving research and development programs for about three decades now and are on the verge of entering large scale utilization in the form of Coated Conductors (CCs), a robust and flexible tape architecture that enables textured growth of the rather brittle material class. A remaining bottleneck for widespread CC implementation is the high cost/performance ratio, essentially controlled by the complex and decelerating step of HTS layer growth. In this thesis we challenge the throughput and cost constraints of conventional growth methods through development of a novel growth technique that combines Chemical Solution Deposition (CSD), an inherently low-cost precursor deposition approach, with a high growth rate, non-equilibrium growth scheme that allows the formation of a transient (Ba-Cu-O) liquid phase prior to crystallization of the final product phase: Transient Liquid-Assisted Growth via CSD (TLAG-CSD). We employed the new process to grow YBa2Cu3O7-d (YBCO) thin films, a cuprate-based HTS material with unmatched current carrying performance in applied magnetic field conditions and at high temperatures. The unprecedented properties can only be reached if the electrically anisotropic compound exhibits biaxial texture and provides sufficient nanometric defects to pin vortices. Hence, not only is the fundamental understanding of the TLAG-CSD process required but also ways to promote epitaxial growth at high rates, avoidance of any current-degrading sources and strategies to enrich the pinning landscape. To tackle these challenges, we combined several advanced characterization methods: In-situ growth experiments at a synchrotron facility were carried out to follow growth kinetics under variation of total and oxygen partial pressures, growth temperatures, heating ramps, film thickness/composition and nanoparticle (NP) addition. The combined set of experiments was successfully summarized in the form of so-called kinetic phase diagrams, a visual representation of the out-of-equilibrium processes and a roadmap for its utilization. Epitaxial, c-axis oriented YBCO films were thoroughly studied via X-ray diffraction, transmission electron microscopy (TEM), low temperature electrical transport and inductive measurements to identify process related limitations and opportunities. This includes probing of the YBCO microstructuture and intrinsic electrical properties to avoid liquid induced substrate reactivity, segregation of secondary phases, while enabling proper CO2 elimination and oxygen doping of the crystal structure. We disclose that epitaxial layer growth rates above 100nm/s can be accomplished through the TLAG-CSD approach, surpassing conventional techniques used in CC manufacturing schemes (TFA-CSD/PLD/MOCVD) by up to two orders of magnitude. Superconducting films are demonstrated to reach high epitaxial grain alignment (Δω<0.6º and Δφ<1º), optimal critical temperatures (Tc=88-92K) and competitive critical current densities (Jc(77K)=2-5MA/cm2). We further classify the TLAG-CSD process as highly versatile in enriching the vortex pinning landscape, not only through its capability to promote a high density of stacking faults and small ab-oriented YBCO grains (5-10nm) in pristine YBCO films, but also through its compatibility with preformed nanoparticle addition in nanocomposites.
12
Vedantham, Vikram. "In-situ temperature and thickness characterization for silicon wafers undergoing thermal annealing." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/1181.
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Nano scale processing of IC chips has become the prime production technique as the microelectronic industry aims towards scaling down product dimensions while increasing accuracy and performance. Accurate control of temperature and a good monitoring mechanism for thickness of the deposition layers during epitaxial growth are critical parameters influencing a good yield. The two-fold objective of this thesis is to establish the feasibility of an alternative to the current pyrometric and ellipsometric techniques to simultaneously measure temperature and thickness during wafer processing. TAP-NDE is a non-contact, non-invasive, laser-based ultrasound technique that is employed in this study to contemporarily profile the thermal and spatial characteristics of the wafer. The Gabor wavelet transform allows the wave dispersion to be unraveled and the group velocity of individual frequency components to be extracted from the experimentally acquired time waveform. The thesis illustrates the formulation of a theoretical model that is used to identify the frequencies sensitive to temperature and thickness changes. The group velocity of the corresponding frequency components is determined and their corresponding changes with respect to temperature for different thickness are analytically modeled. TAP-NDE is then used to perform an experimental analysis on Silicon wafers of different thickness to determine the maximum possible resolution of TAP-NDE towards temperature sensitivity, and to demonstrate the ability to differentiate between wafers of different deposition layer thickness at temperatures up to 600?C. Temperature resolution is demonstrated for ?10?C resolution and for ?5?C resolution; while thickness differentiation is carried out with wafers carrying 4000? and 8000? of aluminum deposition layer. The experimental group velocities of a set of selected frequency components extracted using the Gabor Wavelet time-frequency analysis as compared to their corresponding theoretical group velocities show satisfactory agreement. As a result of this work, it is seen that TAP-NDE is a suitable tool to identify and characterize thickness and temperature changes simultaneously during thermal annealing that can replace the current need for separate characterization of these two important parameters in semiconductor manufacturing.
13
Brunner, Matthias Herbert. "In-situ measurement of blade heat transfer coefficients and gas recovery temperature." kostenfrei, 2007. http://e-collection.ethbib.ethz.ch/view/eth:29954.
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Kumar, Richi. "In situ nanotomography investigation of cavity nucleation and growth in light alloys during high temperature deformation." Thesis, Université Grenoble Alpes (ComUE), 2019. https://thares.univ-grenoble-alpes.fr/2019GREAI065.pdf.
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La déformation à haute température induit la germination, la croissance et la coalescence de cavités, domaine très étudié en science des matériaux. Plusieurs modèles théoriques ont été proposés pour prédire la nucléation et la croissance de la cavité mais la comparaison avec l’expérience est limitée. La principale raison en est le manque d'outils de caractérisation appropriés permettant d'étudier in situ la nucléation et la croissance des cavités à haute résolution spatiale (inférieure à 1 µm).Dans le cadre de ce travail, la nanotomographie in situ aux RX a été mise au point pour l'étude des déformations à haute température. Deux dispositifs mécaniques pouvant s'adapter dans un four ont été développés : ceci permet de réaliser une analyse 4D in situ des dommages à haute température (inférieure à 1073 K). De plus, des routines d'acquisition de données à résolutions multiples ont été mises au point, ce qui a permis d'obtenir alternativement des images à haute résolution (100 nm) et à basse résolution (645 nm). Ces développements ont permis l'imagerie 4D de la germination et de la croissance de l’endommagement avec une taille de pixels de 100 nm et un temps de balayage de 7 secondes. Ces données expérimentales ont été comparées aux modèles théoriques par el suivi du volume de chaque cavité.Cette technique a été utilisée pour étudier la nucléation et la croissance des dommages lors de déformations à haute température (7,9 MPa, 698 K), dans un alliage d'Al -3,6% en poids de Cu. Cet alliage modèle permet la génération contrôlée de particules de seconde phase pour favoriser la germination des cavités. Les changements de forme des cavités avec la déformation ont été étudiés. De plus, le changement du taux de croissance volumétrique de la cavité par rapport au rayon équivalent des cavités individuelles a été comparé aux modèles existants de croissance de la cavité par diffusion et plasticité. On a constaté la présence de plusieurs porosités préexistantes dans l'alliage, alors que très peu de germination de cavité ont été observées. Les données expérimentales sur le taux de croissance correspondent bien aux modèles étudiés et il a été conclu que les cavités se développaient initialement par diffusion suivi par une croissance par plasticité.L'utilisation de la nanotomographie in situ a été étendue à l'étude de la nucléation et de la croissance pendant la déformation à haute température (3,2 MPa, 673 K) dans l'alliage commercial AZ31. L'évolution de petites cavités presque sphériques en cavités complexes a été étudiée, en analysant les changements de forme pendant la croissance. Le taux de croissance volumétrique de la cavité a également été calculé et comparé aux modèles de diffusion et de glissement aux joints de grain. Dans un cas particulier, le glissement aux joints de grain a été estimé en suivant les déplacements des intermétalliques qui servaient de marqueurs.Peu de germination de cavité ont été observées au cours de la déformation, par contre les cavités préexistantes, issues du laminage, ont évolué en taille avec la déformation. L'examen des formes des cavités a révélé que la diffusion et le glissement aux joints de grain sont les mécanismes principaux de la croissance. La diffusion dominant la croissance dans les premiers stades (déformation inférieure à 0,3) puis une combinaison des deux mécanismes gouverne la croissance. Le modèle de croissance par diffusion surestime les données expérimentales tandis que les modèles de diffusion restreinte s’ajustent mieux aux évolutions de volume des cavités. Une proportionnalité directe a été observée entre le du grain et la longueur de la cavité dans une cavité où la croissance est dominée par le glissement aux joints de grain. De plus, outre la croissance, une proportion importante de cavités a montré une diminution du volume pendant la déformation. Ceci a été attribué au frittage des cavités sous l'effet de la tension superficielleHigh temperature deformation proceeds in nucleation, growth and coalescence of voids or creep cavities. Hence investigation of damage in form of cavities during high temperature deformation has been a subject of great interest for researchers over the years. Several theoretical models have been proposed to predict cavity nucleation and growth. However despite significant progresses with theoretical models, the experimental investigation of these models have been handful. The main reason for this has been a lack of suitable characterization tools that allows in situ investigation of nucleation and growth of cavities at high spatial resolution (smaller than 1 µm).In the present work a technique for in situ nanotomography investigation during high temperature deformation has been developed. This involved development of two mechanical devices that could fit in a furnace in order to perform 4D in situ damage analysis at high temperature (below 1073 K). Additionally multi resolution data acquisition routines were developed which allowed imaging at high (100 nm) and low resolution (645 nm) periodically. These developments allowed 4D imaging of damage nucleation and growth in form of creep cavities at 100 nm pixel size and scan time of 7 seconds. Thanks to this nucleation and volumetric growth of individual cavities could be tracked during deformation which could in turn be compared to theoretical models.This technique has been used to study nucleation and growth of damage during high temperature deformation (7.9 MPa, 698 K), in Al -3.6 wt% Cu alloy. This model alloy allows controlled generation of second phase particles to promote cavity nucleation and has hence been chosen for the study. Changes in shape of cavities with straining has been examined. Also, the change of volumetric cavity growth rate vs equivalent radius of individual cavities has been compared to existing models of cavity growth by diffusion and plasticity. It was seen that several pre-existing porosities were present in the alloy, while very few cavity nucleations were observed. The experimental data of growth rate matched well with the studied models and it was concluded that cavities initially grew by diffusion, while the growth mechanism changed to plasticity near failure.Further the use of in situ nanotomography has been extended to studying nucleation and growth during high temperature deformation (3.2 MPa, 673 K) in commercial AZ31 alloy. Evolution of small nearly spherical cavities into complex cavities has been studied, by analysing changes in shape during growth. Volumetric cavity growth rate has also been computed and compared to diffusion and grain boundary sliding models. In a specific case grain boundary sliding was calculated by tracking the displacements of intermetallics which acted as markers. Influence of this on a cavity present on the sliding boundary has been studied.Few cavity nucleations were seen during deformation while most of the damage proceeded in growth of pre-existing cavities. Examination of cavity shape indicated diffusion and grain boundary sliding as the dominant mechanisms driving growth. Diffusion dominating growth in early stages (strain below 0.3) of deformation while later an interplay of the two mechanism caused growth. On comparing volumetric growth data with experimental results it was seen that conventional grain boundary diffusion model over predicted growth rate, while constrained diffusion models were successful in predicting growth rate in the correct order of magnitude as seen experimentally. A direct proportionality was observed between grain boundary displacement and cavity length in a cavity where growth dominated by grain boundary sliding. Additionally apart from growth considerable proportion of cavities showed a decrease in volume during deformation. This was attributed to sintering of cavities under the effect of surface tension
15
Dlugocz, Stephen, and Klaus-Dieter Becker. "Investigating diffusion processes in solids under in situ conditions using high-temperature optical spectroscopy." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-186728.
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Dlugocz, Stephen, and Klaus-Dieter Becker. "Investigating diffusion processes in solids under in situ conditions using high-temperature optical spectroscopy." Diffusion fundamentals 12 (2010) 35, 2010. https://ul.qucosa.de/id/qucosa%3A13880.
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Osorno, Andres. "Dynamic, In-Situ Pressure Measurements during CMP." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7497.
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A rotational setup for measuring interfacial fluid pressure and temperature was successfully constructed. Interfacial fluid measurements were performed with various slurries, slurry flow rates, and pad topographies. It was experimentally determined that the pad topography has the biggest effect in pressure and temperature distribution. This was also confirmed by tilt experiments ran in a rotational environment. For all cases, the edge high conditioned pad displayed the most changes during the experiments.
For an edge high conditioned pad, the fluid pressure was found to be mostly subambient reaching levels of up to 42 kPa at the center of the fixture, and dissipating towards the edges. The pressure maps appear to be almost center symmetric. The pressure was found to be positive during the first second of contact, and rapidly turn subambient. The Subambient pressures stabilize after about 5 seconds, and their suction force was found to slow the rotating platen significantly. Suction forces were confirmed by displacement observed during the tilt experiments. The fixtures center was sucked down into the pad up to 20 m, and tends to tilt towards the leading edge.
Interfacial temperatures were also found to vary with pad geometry. The edge-high conditioned pad exhibited changes of up to 4 C, concentrated at the center. The relative position and shape of these temperature rises matches the results observed in the pressure experiments. Temperature takes a longer time to reach equilibrium, up to 30 seconds in most measurements.
18
Lancaster, Peter Felton. "The surface signature of mesoscale variability in the North East Atlantic using satellite SST and in-situ data." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261850.
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Subramaniam, Srinivas. "In Situ High Temperature Environmental Scanning Electron Microscopic Investigations of Sintering Behavior in Barium Titanate." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155575558.
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Berlin, Katja. "In-situ transmission electron microscopy on high-temperature phase transitions of Ge-Sb-Te alloys." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19219.
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Das Hochtemperaturverhalten beeinflusst viele verschiedene Prozesse von der Materialherstellung bis hin zur technologischen Anwendung. In-situ Transmissionselektronenmikroskopie (TEM) bietet die Möglichkeit, die atomaren Prozesse während struktureller Phasenübergänge direkt und in Realzeit zu beobachten. In dieser Arbeit wurde in-situ TEM angewendet, um die Reversibilität des Schmelz- und Kristallisationsprozesses, sowie das anisotropen Sublimationsverhaltens von Ge-Sb-Te (GST) Dünnschichten zu untersuchen. Die gezielte Probenpräparation für die erfolgreiche Beobachtung der Hochtemperatur-Phasenübergänge wird hervorgehoben. Die notwendige Einkapselung für die Beobachtung der Flüssigphase unter Vakuumbedingungen und die erforderliche sauberer Oberfläche für den Sublimationsprozess werden detailliert beschrieben. Außerdem wird die Elektronenenergieverlustspektroskopie eingesetzt um die lokale chemische Zusammensetzung vor und nach den Übergängen zu bestimmen. Die Untersuchung der Grenzflächenstruktur und Dynamik sowohl beim Phasenübergang fest-flüssig als auch flüssig-fest zeigt Unterschiede zwischen den beiden Vorgängen. Die trigonale Phase von GST weist beim Schmelzen eine teilweise geordnete Übergangszone an der fest-flüssig-Grenzfläche auf, während ein solcher Zwischenzustand bei der Erstarrung nicht entsteht. Außerdem läuft der Schmelzvorgang zeitlich linear ab, während die Kristallisation durch eine Wurzelabhängigkeit von der Zeit mit überlagerter Start-Stopp-Bewegung beschrieben werden kann. Der Einfluss der Substrat-Grenzfläche wird diskutiert und die Oberflächenenergie von GST bestimmt. Die anisotrope Dynamik führt beim Phasenübergang fest-gasförmig der kubischen Phase von GST zur Ausbildung stabiler {111} Facetten. Dies erfolgt über die Bildung von Kinken und Stufen auf stabilen Terrassen. Die Keimbildungsrate und die bevorzugten Keimbildungsorte der Kinken wurden identifiziert und stimmen mit den Voraussagen des Terrassen-Stufen-Kinken Modells überein.High-temperature behavior influence many different processes ranging from material processing to device applications. In-situ transmission electron microscopy (TEM) provides the means for direct observation of atomic processes during structural phase transitions in real time. In this thesis, in-situ TEM is applied to investigate the reversibility of the melting and solidification processes as well as the anisotropic sublimation behavior of Ge-Sb-Te (GST) thin films. The purposeful sample preparation for the successful observation of the high-temperature phase transitions is emphasized. The required encapsulation for the observation of the liquid phase inside the vacuum conditions and the necessary clean surface for sublimation process are discussed in detail. Additionally electron energy-loss spectroscopy in the TEM is used to determine the local chemical composition before and after the phase transitions. The analysis of the interface structure and dynamic during the solid-to-liquid as well as the liquid-to-solid phase transition shows differences between both processes. The trigonal phase of GST exhibits a partially ordered transition zone at the solid-liquid interface during melting while such an intermediate state does not form during solidification. Additionally the melting process proceeds with linear dependence on time, whereas crystallization can be described as having a square-root time-dependency featuring a superimposed start-stop motion. The influence of the interface is addressed and the surface energies of GST are determined. The anisotropic dynamic of the solid-to-gas phase transition of the cubic GST phase leads to the formation of stable {111} facets. This happens via kink and step nucleation on stable terraces. The nucleation rates and the preferred kink nucleation sites are identified and are in accordance with the predictions of terrace-step-kink model.
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Erdogan, Selahattin. "Synthesis Of Liquid Crystalline Copolyesters With Low Melting Temperature For In Situ Composite Applications." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613306/index.pdf.
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The objective of this study is to synthesize nematic-thermotropic liquid crystalline polymers (LCP) and determine their possible application areas. In this context, thirty different LCP&rsquos were synthesized and categorized with respect to their fiber formation capacity, melting temperature and mechanical properties. The basic chemical structure of synthesized LCP&rsquo
s were composed of p-acetoxybenzoic acid (p-ABA), m-acetoxybenzoic acid (m-ABA), hydroquinone diacetate (HQDA), terephthalic acid (TPA) and isophthalic acid (IPA) and alkyl-diacids monomers. In addition to mentioned monomers, polymers and oligomers were included in the backbone such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) polymers, and polybutylene naphthalate (PBN), polyhexylene naphthalate (PHN) and poly butylene terephthalate (PBT) oligomers that contain different kinds of alkyl-diols. We adjusted the LCP content to have low melting point (180oC-280oC) that is processable with thermoplastics. This was achieved by balancing the amount of linear (para) and angular (meta) groups on the aromatic backbones together with the use of linear hydrocarbon linkages in the random copolymerization (esterification) reaction. LCP species were characterized by the following techniques
Polarized Light Microscopy, Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Analysis (FTIR), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), X-ray Scattering (WAXS, Fiber diffraction), surface free energy, end group analysis (CEG), intrinsic viscosity (IV) and tensile test. According to these analysis LCPs were classified into five main categories
(I) fully aromatics, (II) aromatics+ PET/PEN, (III) aromatics + oligomers (IV) aromatics + short aliphatic diacids, (V) aromatics + long aliphatic diacids. The foremost results of the analysis can be given as below. DSC analysis shows that some LCPs are materials that have stable LC mesogens under polarized light microscopy. In TGA analysis LCPs that have film formation capacity passed the thermal stability test up to 390oC. NMR results proved that predicted structures of LCPs from feed charged to the reactor are correct. In FTIR due to the inclusion of new moieties, several peaks were labeled in the finger-print range that belongs to reactants. In X-ray analysis, LCP24 (containing PET) was found to be more crystalline than LCP25 (containing PEN) which is due to the symmetrical configuration. Block segments were more pronounced in wholly aromatic LCP2 than LCP24 that has flexible spacers. Another important finding is that, as the amount of the charge to the reactor increases CEG value increases and molecular weight of the product decreases. Selected group V species were employed as reinforcing agent and mixed with the thermoplastics
acrylonitrile butadiene styrene (ABS), nylon6 (PA6), polyethylene terephthalate (PET), polypropylene (PP) and appropriate compatibilizers in micro compounder and twin screw extruder. The blends of them were tested in dog-bone and/or fiber form. In general LCPs do not improve the mechanical properties except in composite application with polypropylene. A significant increase in tensile properties is observed by LCP24 and LCP25 usage. Capillary rheometer studies show that the viscosity of ABS decreases with the inclusion PA6 and LCP2 together. In addition to the composite applications, some LCPs are promising with new usage areas. Such as nano fibers with 200nm diameter were obtained from LCP27 by electrospinning method. The high dielectric constant of LCP29 has shown that it may have application areas in capacitors.
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Huang, Xi. "In-situ conductivity, temperature, and dissolved oxygen (CT-DO) sensor system for marine measurement." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/336240/.
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This works describes the development of a miniature high accuracy, low power CT-DO sensor system for in-situ oceanographic measurements. The sensors were fabricated on glass wafers, using micro-fabrication techniques. Three chip designs were made. The sensors in designs 1 and 2 include a seven-electrode conductivity sensor set in a flow channel, a four-ring-electrode open conductivity sensor, a Platinum Resistance Thermometer (PRT) bridge temperature sensor, and a DO sensor based on a platinum electrode inset into five 25 μm deep wells. A 16-bit impedance measurement circuit was made to support the CT sensor. This has a typical battery life of one month with 10 s sampling interval. The initial CT accuracies are ±0.01 mS/cm and ±0.003 oC respectively. The seven-electrode conductivity sensor with channel suffered from a durability problem, which was discovered on a mid-Atlantic deployment. This problem was solved with the four-ringelectrode open conductivity and PRT bridge temperature sensor. Dock deployments and 8-week test in a calibration lab showed that the monthly drift was 0.02 mS/cm for the conductivity sensor, and less than 0.01 oC for the temperature sensor. The DO sensor was calibrated to have an initial accuracy of ±5 μm. A simple analytical model is proposed to estimate the effect of fluid flow. Tests show that the measured flow effect leads to an error of 1% DO, compared with an estimate of 10%. The complete CT-DO sensor was tested during a 75 day Indian Ocean cruise. A novel method of bio-fouling mitigation was tested utilizing electro-chemical reactions on the electrodes of the conductivity and DO sensors, and first results are promising. The CT system was also modified to measure low-conductivity solutions. This system was deployed in Greenland and results showed that the CT sensor can also work in fresh water and harsh environments. Future plans are to integrate the electronics into an ASIC, and to include a miniature sensor chip (design 3), to make a package the size of a pen for fish tag applications.
23
Koumpouras, Georgios. "Mathematical modelling of a low-temperature hydrogen production process with in situ CO₂ capture." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/8211.
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Deshpande, Anushree. "Synthesis and Characterization of in-situ Nylon-6/Epoxy Blends." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1480328231030708.
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ESPINOZA, Nikolai da Silva. "Avaliação da ilha de calor urbana em Manaus com dados observados in situ e sensoriamento remoto." Universidade Federal de Campina Grande, 2017. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1429.
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Capes
A ilha de calor urbana (ICU) é um fenômeno importante devido aos seus impactos diretos e indiretos sobre as populações humanas em ambientes urbanos. Esse fenômeno tem sido estudado amplamente usando tanto medições diretas a partir de sensores de temperatura do ar instalados em estações meteorológicas ou a bordo de veículos, como dados de temperatura da superfície medidos por sensoriamento remoto. Neste trabalho foi avaliada a variabilidade temporal e espacial da ICU na cidade de Manaus utilizando dados de precipitação, temperatura e umidade do ar em cinco estações meteorológicas distribuídas na área urbana e uma na área rural durante o período de julho de 2013 a julho de 2014. Adicionalmente, foram obtidas imagens do sensor OLI/TIRS a bordo do satélite Landsat 8 em quatro dias da estação menos chuvosa para estimar a temperatura da superfície e parâmetros de superfície, tais como o NDVI na área que estão inseridas as estações meteorológicas. Os resultados indicaram que a ICU atmosférica ocorre preferencialmente no período noturno, sendo mais intensa e condicionalmente desconfortável durante a estação seca da região. A partir das imagens de satélite, pode-se observar uma relação inversamente proporcional entre a temperatura da superfície e o NDVI, onde a maior variação de temperatura da superfície está localizada em áreas com pouca ou nenhuma vegetação.
The urban heat island (ICU) is an important phenomenon due to its direct and indirect impacts on human populations in urban environments. This phenomenon has been studied extensively using both direct measurements from air temperature sensors installed in fixed weather stations or mobile surveys using automobiles and remotely measured surface temperature data. This work evaluated the temporal and spatial variability of ICU in the city of Manaus using precipitation, temperature and air humidity data in five meteorological stations distributed in the urban area and one in the rural area during the period from July 2013 to July 2014. In addition, images of the Landsat 8 OLI / TIRS satellite were obtained in four days of the less rainy season to estimate the surface temperature in the area comprising the meteorological stations. The results indicated that atmospheric ICU occurs preferentially at night, being more intense and conditionally uncomfortable during the dry season of the region. From the satellite images, an inversely proportional relationship between the surface temperature and the NDVI can be observed, where the highest surface temperature variation is located in areas with little or no vegetation.
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GONCALVES, IRACI M. P. "Determinacao do tempo de resposta de sensores de temperatura do tipo RTD atraves de medidas in situ." reponame:Repositório Institucional do IPEN, 1985. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9849.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Anderegg, David Alexander. "In-Situ Monitoring and Simulations of the Non-Isothermal Crystallization of FFF Printed Materials." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/99303.
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This thesis is concerned with the development of methods and models to aid in optimization and development of new materials for Fused Filament Fabrication (FFF). We demonstrate a novel FFF nozzle design to enable the first measurements of in-situ rheology inside FFF nozzles, which is critical for part performance by ensuring that the polymer extrudate is flowing at an appropriate temperature and flow rate during the part build process. Testing was performed using Acrylonitrile butadiene styrene filament and a modified Monoprice Maker Select 3D printer. Tests using the default temperature control settings of the printer showed an 11 °C drop in temperature and significant fluctuations in pressure, during printing and while idle, of ± 2 °C and +/-14 kPa. These deviations were eliminated at lower flow rates with a properly calibrated proportional–integral–derivative (PID) system. At high flow rates, drops in temperature as high as 6.5 °C were observed even with a properly calibrated PID, providing critical input to the impact of flow rate and PID calibration on polymer melt temperature inside FFF nozzles. Pressure readings ranging from 140-6900 kPa were measured over the range of filament feed rates and corresponding extrusion flow rates. Theoretical predictions of pressure profiles, assuming a powerlaw fluid model, matched well with experimental results. Our nozzle prototype succeeded in measuring internal conditions of FFF nozzles for the first time, thereby providing several important insights into the printing process which are vital for monitoring and improving FFF printed parts.
Furthermore, finite difference simulations based on first principles analysis are presented which are capable of quantifying the effect of processing conditions on the properties of semicrystalline parts made by FFF. Each layer was modelled as a rectangular cross section which was broken down into smaller elements for modelling. Crystallinity of each element was calculated using a parallel Avrami model which accounts for changes in crystallization rate due to temperature and multiple crystallization mechanisms. The amount of polymer diffusion, also referred to as the degree of healing, was calculated using a novel incremental diffusion model which accounted for not only changes in reptation time due to temperature but also restrictions to healing due to crystallinity. To the authors knowledge, this is the first healing model capable of accounting for the effect of crystallinity on healing and is relevant to any process involving healing of crystalline interfaces; not just FFF. Cumulative shear stresses between each layer and at the bottom of the part were also calculated for the first time using a force balance model by assuming constant shear strain throughout each layer. Simulations were performed using typical printing conditions for polyether ether ketone. In the first layer of a 24 layer part, the average degree of crystallinity, healing, and shear stress were 25.0%, 53.8% and 19.4 MPa respectively. The degree of crystallinity and healing at layer 22 (which represented the steady state values) were 18.4-25.0% and 51.4% respectively. When crystallinity was not accounted for, varying the printing parameters and material properties supported the use of high temperatures and specific heat in addition to a low printing speed, heat transfer coefficient, and thermal conductivity to maximize part properties. These conditions also supported crystallization, however, which led to a simultaneous reduction in the part properties when crystallinity was taken into account. These contradictory effects will need to be considered when optimizing the printing parameters, though the optimal balance will be highly dependent on the material used and the limitations of the printer.
Experimental validation of the accuracy of the heat transfer and polymer diffusion models was performed using an amorphous polymer (polyether imide). Single road wide parts were printed at various nozzle temperatures, bed temperatures, and printing speeds and the results were compared to the simulated results. The predicted shear stress in the bottom of the part ranged from 2.3-3.8 MPa and correlated to warpages at the corners of each part of 1.2-2.4 mm. A linear increase in warpage with predicted shear stress was observed supporting the shear stress model. Predicted degrees of healing ranged from 2-90% but the experimental results ranged from 15-36%. Results of the healing model underpredicted strength at low printing speeds and over predicted strength at high printing speeds. The experimental validations showed the capabilities of the models, but the effect of printing speed will need to be investigated further to improve the accuracy of the healing model.MS
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Padovani, Stéphane. "Etude par stm a temperature variable et kerr in situ de nanostructures de co/au(111)." Université Louis Pasteur (Strasbourg) (1971-2008), 1999. http://www.theses.fr/1999STR13171.
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La croissance du cobalt sur la face (111) de l'or par epitaxie a jet atomique a ete etudiee pour des recouvrements compris entre 0. 3 et 6 monocouches (mc). Conjointement a cette etude de croissance, des mesures magnetiques ont ete realisees. La croissance ainsi que les mesures ont ete faites dans une enceinte ultravide. Le depot de co a ete caracterise par microscopie a effet tunnel, spectroscopie auger et diffraction d'electrons lents. Les mesures magnetiques ont ete faites in situ par effet kerr, ex situ par squid et magnetometrie a gradient de champ alternatif. Si le depot est realise a temperature ambiante, les coudes de la reconstruction en chevrons sont des sites preferentiels de nucleation pour les adatomes de co. En utilisant cette croissance particuliere, il est montre que pour des recouvrements inferieurs a la monocouche, le depot de co est un reseau d'ilots bi-couches, formes sur les coudes de la reconstruction. Pour un recouvrement d'environ 1 mc, les ilots coalescent, formant ainsi un reseau de chaines de cobalt. Pour des recouvrements superieurs, les chaines coalescent jusqu'a former un film granuleux mais continu pour 3 mc. Les proprietes magnetiques, pour ces differents recouvrements, sont simulees a l'aide d'un modele heisenberg anisotrope. L'effet d'un recuit a ete etudie sur les ilots et sur les films, montrant une diffusion du cobalt dans l'or. La croissance a basse temperature a ete etudiee pour des temperatures de depot comprises entre 30 et 250 k. Si cette temperature est inferieure a 50 k, le cobalt ne se nuclee plus sur les coudes de reconstruction, les ilots formes sont monocouches, autorisant ainsi une croissance quasi couche par couche. Une anisotropie magnetique planaire est mesuree pour des recouvrements superieurs a 1. 7 mc tant que la temperature reste comprise entre 30 et 250 k, juste apres depot. Au-dela de 250 k, l'axe d'anisotropie se reoriente perpendiculairement a la surface pour des epaisseurs inferieures a 5 mc.
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Baier, Sina, Christian D. Damsgaard, Maria Scholz, Federico Benzi, Amélie Rochet, Robert Hoppe, Torsten Scherer, et al. "In Situ Ptychography of Heterogeneous Catalysts using Hard X-Rays: High Resolution Imaging at Ambient Pressure and Elevated Temperature." Cambridge University Press, 2016. https://tud.qucosa.de/id/qucosa%3A70694.
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A new closed cell is presented for in situ X-ray ptychography which allows studies under gas flow and at elevated temperature. In order to gain complementary information by transmission and scanning electron microscopy, the cell makes use of a Protochips E-chipTM which contains a small, thin electron transparent window and allows heating. Two gold-based systems, 50 nm gold particles and nanoporous gold as a relevant catalyst sample, were used for studying the feasibility of the cell. Measurements showing a resolution around 40 nm have been achieved under a flow of synthetic air and during heating up to temperatures of 933 K. An elevated temperature exhibited little influence on image quality and resolution. With this study, the potential of in situ hard X-ray ptychography for investigating annealing processes of real catalyst samples is demonstrated. Furthermore, the possibility to use the same sample holder for ex situ electron microscopy before and after the in situ study underlines the unique possibilities available with this combination of electron microscopy and X-ray microscopy on the same sample.
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Boychuk, O. V. "Electrochemical Impedance Spectroscopy Study In-Situ State of Health of the Alkaline Zn-Mno2 Batteriesunder Changing of Thermal Modes." Thesis, Київський національний університет технологій та дизайну, 2017. https://er.knutd.edu.ua/handle/123456789/8396.
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Wilson, Trevor Stewart. "The research and development of in situ non-intrusive optical and temperature diagnostics in an internal combustion engine." Thesis, University of Warwick, 2002. http://wrap.warwick.ac.uk/3588/.
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Novel instrumentation has been developed and evaluated in a low-cost, purpose built, single-cylinder internal combustion engine test facility designed to simulate many of the combustion features that are common between an internal combustion engine, a gas turbine combustor and a steel rolling furnace. High bandwidth in-cylinder surface temperature measurements are demonstrated with a new application of platinum thin film resistance thermometers. These gauges are exposed to the combustion gases and are mounted to both the cylinder head and piston. It is shown that calculation of flame speed, determination of heat flux levels and flame structure observation are possible. Fibre optic probes capable of high frequency spectral measurements of the combustion emission are presented. The spectral measurements are shown to complement the temperature measurement by being able to differentiate the flame front from the general combustion emission and hot by-products. Beyond this, other optical techniques have been explored in order to gain an understanding of the flame front and flow within the combustion chamber. The novel spark plug described is capable of combustion imaging and its application to in-cylinder PIV and flow visualisation is demonstrated. Combustion modelling has been undertaken using published engine models and a comparison between measured and predicted values of pressure and heat flux is provided as a validation of the in-cylinder heat flux measurements.
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WAN, JINGFANG. "In Situ Optically Trapped Probing System for Molecular Recognition and Localization." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250626752.
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Malvestam, Daniel. "Implementation of an In-situ Non-contact Temperature Controller for Active Thermal Fatigue Tests of Power Electronics." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-97059.
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A controller with thermopile IR-sensors is developed to monitor and control the temperature of power electronics during active accelerated thermal fatigue tests - power cycling. Bond wiring is the dominating method for connecting semiconductors to the package leads, distance points on a chip or chip modules within a package. 25-30\% of all package related failures of electronic devices during their operation life time can be related to bond wire failures. To test bond wires, power cycling test can be performed to stimulate failures in bond wire connections, enabling for further development and improvements in the area of bond wires. At IMTEK (Department for microsystems engineering) University of Freiburg, new types of aluminium/copper fibre-reinforced bond wires with a diameter 300 micrometers for power electronics are tested together with a power cycling equipment. During a power cycling test the component is periodically heated, with a current flow through the chip, and cooled down. These new bond wires are bonded on IGBT (Insulated Gate Bipolar Transistor) modules. Since it is possible to measure the overall temperature (mean value) of the chip, using IR-sensors, the developed´controller in this final thesis is robust. Further, the implemented controller can easily be extended for power cycling with e.g. 10 modules in parallel.
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Appelblad, André. "Development of a Temperature Controlled Cell for Surface Enhanced Raman Spectroscopy for in situ Detection of Gases." Thesis, Umeå universitet, Institutionen för fysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-89799.
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This work describes a master’s thesis in engineering physics at Umeå University carried out during the spring semester of 2014. In the thesis the student has constructed and tested a temperature controlled cell for cooling/heating of surface-enhanced-Raman-spectroscopy (SERS) substrates for rapid detection of volatile substances. The thesis was carried out at the Swedish Defence Research Agency (FOI) in Umeå, Sweden. A Linkam Scientific Instruments TS1500 cell was equipped with a Peltier element for cooling/heating and a thermistor temperature sensor. A control system was constructed, based on an Arduino Uno microcontroller board and a pulse-width-modulated (PWM) H-bridge motor driver to control the Peltier element using a proportional-integral (PI) control algorithm. The temperature controlled cell was able to regulate the temperature of a SERS substrate within -15 to +110 °C and maintain the temperature over prolonged periods at ±0.22 °C of the set point temperature. Gas phase of 2-chloro-2-(difluoromethoxy)-1,1,1-trifluoro-ethane (isoflurane) was flowed through the cell and SERS spectra were collected at different temperatures and concentrations. This test showed that the signal is increased when the substrate is cooled and reversibly decreased when the substrate was heated. Keywords: temperature control, Raman scattering, surface enhanced Raman spectroscopy SERS, SERS substrate, volatile substances, Peltier module, thermistor, PWM, H-bridge, PI(D) control.Detta dokument beskriver ett examensarbete för civilingenjörsexamen i teknisk fysik vid Umeå Universitet som utförts under vårterminen 2014. I examensarbetet har en kyl-/värmecell för temperaturkontroll av substratytor för ytförstärkt ramanspektroskopi (SERS) för snabb detektion av farliga flyktiga ämnen konstruerats och testats. Arbetet utfördes vid Totalförsvarets forskningsinstitut (FOI) i Umeå, Sverige. Utgångspunkten var ett Linkam Scientific Instruments TS1500 mikroskopsteg, vilket utrustades med ett Peltierelement för kylning/värmning och en termistor för temperaturövervakning. Ett styrsystem baserat på ett Arduino Uno mikrostyrenhetskort konstruerades med ett motordrivkort (H-brygga) vilket använder pulsbreddsmodulering (PWM) för att reglera spänningen till Peltierelementet utifrån en PI-regulator. Den färdiga cellen klarade att reglera temperaturen på ett SERS-substrat i ett temperaturspann på ungefär -15 till +110 °C med en temperaturstabilitet på ±0.22 °C av måltemperaturen. Cellen testades sedan på flyktiga ämnen för att visa dess funktion. Difluorometyl-2,2,2-trifluoro-1-kloroetyleter (isofluran) i gasfas, med instrumentluft som bärargas, flödades genom cellen och SERS-spektra erhölls vid olika koncentrationer och temperaturer. Vid samtliga koncentrationer visades att lägre temperatur ger ökad signalstyrka. När ytan sedan värmdes upp sjönk signalen reversibelt tillbaka till ursprungsvärdet. Nyckelord: temperaturkontroll, ytförstärkt ramanspektroskopi, SERS, flyktiga ämnen, Peltierelement, thermistor, PWM, H-brygga, PI(D)-regulator.
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Krishnan, Vinu. "LOW TEMPERATURE NITIFE SHAPE MEMORY ALLOYS: ACTUATOR ENGINEERING AND INVESTIGATION OF DEFORMATION MECHANISMS USING IN SITU NEUTR." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3373.
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Shape memory alloys are incorporated as actuator elements due to their inherent ability to sense a change in temperature and actuate against external loads by undergoing a shape change as a result of a temperature-induced phase transformation. The cubic so-called austenite to the trigonal so-called R-phase transformation in NiTiFe shape memory alloys offers a practical temperature range for actuator operation at low temperatures, as it exhibits a narrow temperature-hysteresis with a desirable fatigue response. Overall, this work is an investigation of selected science and engineering aspects of low temperature NiTiFe shape memory alloys. The scientific study was performed using in situ neutron diffraction measurements at the newly developed low temperature loading capability on the Spectrometer for Materials Research at Temperature and Stress (SMARTS) at Los Alamos National Laboratory and encompasses three aspects of the behavior of Ni46.8Ti50Fe3.2 at 92 K (the lowest steady state temperature attainable with the capability). First, in order to study deformation mechanisms in the R-phase in NiTiFe, measurements were performed at a constant temperature of 92 K under external loading. Second, with the objective of examining NiTiFe in one-time, high-stroke, actuator applications (such as in safety valves), a NiTiFe sample was strained to approximately 5% (the R-phase was transformed to B19' phase in the process) at 92 K and subsequently heated to full strain recovery under a load. Third, with the objective of examining NiTiFe in cyclic, low-stroke, actuator applications (such as in cryogenic thermal switches), a NiTiFe sample was strained to 1% at 92 K and subsequently heated to full strain recovery under load. Neutron diffraction spectra were recorded at selected time and stress intervals during these experiments. The spectra were subsequently used to obtain quantitative information related to the phase-specific strain, texture and phase fraction evolution using the Rietveld technique. The mechanical characterization of NiTiFe alloys using the cryogenic capability at SMARTS provided considerable insight into the mechanisms of phase transformation and twinning at cryogenic temperatures. Both mechanisms contribute to shape memory and pseudoelasticity phenomena. Three phases (R, B19' and B33 phases) were found to coexist at 92 K in the unloaded condition (nominal holding stress of 8 MPa). For the first time the elastic modulus of R-phase was reported from neutron diffraction experiments. Furthermore, for the first time a base-centered orthorhombic (B33) martensitic phase was identified experimentally in a NiTi-based shape memory alloy. The orthorhombic B33 phase has been theoretically predicted in NiTi from density function theory (DFT) calculations but hitherto has never been observed experimentally. The orthorhombic B33 phase was observed while observing shifting of a peak (identified to be B33) between the R and B19' peaks in the diffraction spectra collected during loading. Given the existing ambiguity in the published literature as to whether the trigonal R-phase belongs to the P3 or P space groups, Rietveld analyses were separately carried out incorporating the symmetries associated with both space groups and the impact of this choice evaluated. The constrained recovery of the B19' phase to the R-phase recorded approximately 4% strain recovery between 150 K and 170 K, with half of that recovery occurring between 160 K and 162 K. Additionally, the aforementioned research methodology developed for Ni46.8Ti50Fe3.2 shape memory alloys was applied to experiments performed on a new high temperature Ni29.5Ti50.5Pd20 shape memory alloys. The engineering aspect focused on the development of (i) a NiTiFe based thermal conduction switch that minimized the heat gradient across the shape memory actuator element, (ii) a NiTiFe based thermal conduction switch that incorporated the actuator element in the form of helical springs, and (iii) a NiTi based release mechanism. Patents are being filed for all the three shape memory actuators developed as a part of this work. This work was supported by grants from SRI, NASA (NAG3-2751) and NSF (CAREER DMR-0239512) to UCF. Additionally, this work benefited from the use of the Lujan Center at the Los Alamos Neutron Science Center, funded by the United States Department of Energy, Office of Basic Energy Sciences, under Contract No. W-7405-ENG-36.Ph.D.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Materials Science & Engr PhD
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Johnson, Michael Christopher. "In-situ and post-growth investigation of low temperature Group III-nitride thin films deposited via MOCVD /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/9925.
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Janíček, Tomáš. "Vliv hybridizačních směsí na intenzitu fluorescence při in situ hybridizaci." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401944.
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Fluorescenční in situ hybridizace (FISH) je široce používaná metoda pro detekci určité sekvence DNA na chromozomech. Cílem práce je porovnání tří různých chemických sloučenin (formamidu, ethylenkarbonátu a sodných kationtů) používaných ve směsích pro in situ hybridizaci. Složení těchto směsí ovlivňuje renaturaci DNA a je důležité porovnat jejich fyzikální vlastnosti. Práce je rozdělena do dvou hlavních částí. První část se zabývá otázkou termodynamických parametrů používaných pro experimenty FISH, jako je teplota tání, entalpie přechodu DNA ze dvoušroubovice na vlákno nám dává přehled o energii potřebné k tomto přechodu a interakcích mezi bázemi a každou složkou směsi. Kromě toho hodnoty entropie určují poř uvnitř směsi - systém DNA. Druhá část porovnává intenzitu fluorescenčního signálu při optimalizovaných teplotách tání sondy použité pro in situ hybridizaci. Jako sonda byla použita sub-telomerní repetice X43.1, která je umístěna na Y chromozomu rostlinného modelového organismu Silene latifolia. Směs obsahující formamid má nejlepší výkon při delším postupu hybridizace, zatímco ethylenkarbonát poskytuje vyšší intenzitu signálu, a proto je vhodnější pro rychlé FISH protokoly.
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Vasilescu, Andreea-Roxana. "Design and execution of energy piles : Validation by in-situ and laboratory experiments." Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0015/document.
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Les pieux énergétiques représentent une solution alternative intéressante, face à l’accroissement des besoins mondiaux en énergie et à la réduction de l’utilisation des énergies fossiles. L’objectif principal de la thèse est d’identifier et de quantifier les principaux facteurs influençant le dimensionnement des pieux géothermiques, qui sont impactés par les changements de température des pieux lors de leur activité. Pour ce faire, ce travail de thèse a été dressé en 3 campagnes expérimentales, dont deux à échelle réelle : (i) une première campagne à chargement thermomécanique contrôlé (Marne La Vallée), (ii) une seconde campagne en conditions d’utilisation réelles sous une station d’épuration (Sept Sorts) et (iii) une troisième campagne à l’échelle du laboratoire grâce à une nouvelle machine de cisaillement direct d’interface permettant l’étude du comportement thermo mécanique des interfaces sol-structure. Ces trois campagnes expérimentales ont pour but de quantifier l’effet de la température et des cycles de température sur le comportement des pieux énergétiques. Les premiers résultats expérimentaux de la campagne de Sept Sorts ont ensuite été simules dans le code LAGAMINE via la méthode des éléments finis, afin d’adopter une approche complémentaire permettant de mieux appréhender la réponse thermomécanique de ce type de pieu lors de l’activation géothermique. et (iii) une troisième campagne à l’échelle du laboratoire grâce à une nouvelle machine de cisaillement direct d’interface permettant l’étude du comportement thermo mécanique des interfaces sol-structure. Ces trois campagnes expérimentales ont pour but de quantifier l’effet de la température et des cycles de température sur le comportement des pieux énergétiques. Les premiers résultats expérimentaux de la campagne de Sept Sorts ont ensuite été simules dans le code LAGAMINE via la méthode des éléments finis, afin d’adopter une approche complémentaire permettant de mieux appréhender la réponse thermomécanique de ce type de pieu lors de l’activation géothermiqueEnergy piles, also called thermo-active piles, are an alternative solution to the increase in the global energy demand as well as in mitigating socio-economical stakes concerning the increase of energy costs due to fossil fuels. Energy piles are double purpose structures that allow transferring the loads from the superstructure to the soil and that integrate pipe circuits allowing heat exchange between the pile and the surrounding ground. The objective of this thesis is to identify and quantify the principal parameters involved in the geotechnical design of pile foundations impacted by temperature changes associated with geothermal activation. For this purpose, this research work was organized in 3 experimental campaigns: (i) A full scale load controlled test at Ecole des Ponts Paris-Tech, (ii) Full scale energy piles monitoring under real exploitation conditions at Sept Sorts, (Seine et Marne, France), (iii) Laboratory tests in order to assess the effect of temperature and temperature cycles at the soil-pile interface. The experimental results are used to estimate the effect of geothermal activation of a pile foundation, on its bearing capacity as well as on its long-term exploitation. Finally, preliminary numerical simulations were performed using a thermo-hydro mechanical model, using the finite element method code LAGAMINE able to capture the main phenomena
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Jagannathan, Deepak. "Calcium-Silicate-Hydrate in cementitious systems : chemomechanical correlations, extreme temperature behavior, and kinetics and morphology of in-situ formation." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/92651.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 96-102).
Concrete, the second most used material on the planet, is a multi-scale heterogeneous material. A fundamental component known as Calcium-Silicate-Hydrate which forms from the reaction between cement and water is the binding phase in concrete. Curiously, this is the least understood component of concrete because of its porous amorphous structure. Further, beyond mere scientific curiosity, cementS̆s industry large carbon footprint due to its volume of usage sets up a practical context to seek improvements in concrete performance and equip concrete with additional functionalities. It is our contention that we can better understand the least known and crucial component of concrete, Calcium-Silicate-Hydrate, to inform the design of next generation of high performance concrete. With this broad theme, this thesis presents three different aspects of properties of Calcium Silicate Hydrate: chemomechanical correlations, behavior under extreme temperature and pressures, and kinetics and nanostructure of in-situ formation. Calcium Silicate Hydrate (C-S-H) formed in-situ in concrete is believed to have a layered structure with silicate chains similar to crystal structures of Tobermorite and Jennite. Its chemical composition, characterized by Ca/Si ratio, must therefore influence its silicate chain structure and thus its mechanical properties. We explore the correlation between CS- H composition and its mechanical properties. By varying chemical composition of cement clinkers and supplementary cementitious materials, water/cement ratios, and hydration temperatures, we prepare cement pastes with different C-S-H of different C/S ratios. We use nanoindentation and X-ray spectroscopy to respectively measure the mechanical properties and composition of C-S-H. We then study the mechanical performance of C-S-H at elevated temperatures. This is relevant in the design of infrastructure that can sustain extreme events such as blasts and high velocity impacts. As a starting point for concrete that would enable such infrastructure, we use ultra high performance concrete (UHPC). We use nanoindentation and X-ray spectroscopy to respectively measure mechanical properties and composition of individual components of UHPC. We compare the composition and properties of C-S-H found in UHPC to that found in ordinary cement pastes (OPC). Our grid nanoindentation experiments also reveal an artifacts created by the incorporation of steel fiber reinforcements in UHPC. We find that steel fiber reinforcements disrupt the perfect packing of constituent materials in UHPC to create capillary porosity at microscale. Further, we study the mechanical properties of C-S-H in concrete specimens subjected to high temperatures of 400°C and 1000°C. As a product of the reaction between cement and water, the properties of C-S-H are ultimately controlled by the reaction. To obtain quantitative kinetics, we use time-lapse optical microscopy to study hydration of micron sized monoclinic C₃S particles with in droplets of water of 50 [mu]m. Using Raman spectroscopy, we characterize the hydration product growing inside these droplets.
by Deepak Jagannathan.
S.M.
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Schlegel, Robert William. "Comparing in situ and satellite temperature data on the Agulhas Bank to understand changes in anchovy (Engroulis encrasicolus) distribution." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13052.
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Includes bibliographical references.Satellite data have high spatial/ temporal resolution, extensive coverage and are easily accessible, making them a common part of many studies on the oceans. One such important study to use satellite data found a relationship between the cross-shelf SST difference on the Agulhas Bank and the relative distribution of anchovy (Engraulis encrasicolus) spawner biomass east of Cape Agulhas. However, other studies have shown that nearshore satellite data may not be as accurate as originally believed. Using the relationship observed in the aforementioned study as a test, I compared time series' from two types of in situ temperature data to satellite SST data. A combined CTD/CalVET (PISCTD) data set was used for in situ data on the coastal and offshore regions of the Agulhas bank whereas a data set with two UTRs was used for inshore in situ data. None of the data sets correlated significantly with each other, save the two UTRs. Both in situ data sets showed a negative relationship between the size of the cross-shelf temperature difference on the Agulhas bank and the increase in anchovy biomass there, whereas the satellite data showed a positive relationship. This was largely due to the pattern of decadal warming observed in the in situ data whereas the satellite data showed decadal cooling. Even though it was found that the difference in sampling methodology between the satellite and in situ data sets prevented them from being accurately compared, the difference in the annual and decadal patterns between these two types of data do support other findings showing discrepancies between remotely-sensed and in situ data for nearshore environments.
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Darros, Barbosa Roger. "High pressure and temperature dependence of thermodynamic properties of model food solutions obtained from in situ ultrasonic measurements." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0000671.
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Beale, Andrew Michael. "Novel low temperature preparation methods for mixed complex oxide catalysts and their characterisation via in situ SR techniques." Thesis, University College London (University of London), 2003. http://discovery.ucl.ac.uk/1453143/.
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Alvarez, Murga Michelle Jenice. "Microdiffraction et microtomographie in situ des transformations hétérogènes du C¦« sous haute pression et haute température." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENY091/document.
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Le diagramme des phases du C60 continue d'être un sujet de discussion et de controverse, malgré la grande quantité de travaux expérimentaux et théoriques fait au fil des ans. Ceci est principalement dû au manque d'études in situ, a l'existence d´états désordonnés présentant des pics de diffraction très mal résolus et à la coexistence de plusieurs polytypes de faible densité. Ce manuscrit présente une étude systématique in situ des transformations hétérogènes du C60 sous haute pression et haute température dans la gamme 1-10 GPa et 300-1200 K. Afin de discriminer les poly(a)morphes de densité similaire dans des échantillons hétérogènes, nous avons utilisé une combinaison de micro-diffraction et micro-tomographie. Les échantillons ont été synthétisés dans une cellule Paris-Edimbourg et caractérisés à l'aide de diffraction des rayons X in situ en dispersion angulaire. Des images tridimensionnels à haute résolution ont été obtenus sur des échantillons trempés par la méthode de micro-tomographie de diffraction/diffusion. Cette méthode permet l'analyse 3D de l'intensité de diffusion reconstruite à partir de séries de projections 2D. Une telle analyse est non destructive et offre une grande sensibilité (0,1% en volume), une haute résolution spatiale (μm3) et peut être multimodale, fournissant des données quantitatives sur la morphologie, la densité, la composition élémentaire ou la structure des matériaux. En outre, nous décrivons le développement d´un système de micro-tomographie in situ sous haute pression et haute température en utilisant une nouvelle cellule rotative Paris-Edimbourg (RoToPEC), combinée avec le rayonnement synchrotron. La capacité à tourner complètement la chambre de l'échantillon sous charge, surmonte la contrainte d'ouverture angulaire limitée des cellules ordinaires et permet l'acquisition de projections tomographiques pour l'imagerie de plein champ ainsi que pour l'imagerie par micro-diffraction. Cette méthode innovante permet l´étude des matériaux sous conditions extrêmes de pression, température ou stress, et pourra être appliquée dans des domaines variés tels que la physique, la chimie, la science des matériaux ou la géologie. Le potentiel de cette nouvelle technique expérimentale est démontré par l'étude de la polymérisation de C60 sous haute-pression et haute température. Mots-clés: C60, diagramme de phase, diffraction, micro-tomographie, haute pression et haute températureThe C60 reaction diagram continues to be a subject of discussion and controversy, despite the vast amount of experimental and theoretical work done over the years. This is mainly due the lack of in situ studies, the highly disordered-states showing poorly resolved diffraction peaks and the coexistence of several low-density polytypes. This manuscript presents a systematic in situ study of high-pressure–high-temperature forms C60 in the range of 1-10 GPa and 300-1200 K. In order to discriminate poly(a)morphs with similar densities in heterogeneous samples, we used a combination of microdiffraction and microtromography. The samples were synthesized in a Paris-Edinburgh cell and characterized using in situ angular dispersive X-ray diffraction. Three-dimensional submicron images were obtained on quenched samples using diffraction/scattering microtomography. This method provides 3D analysis of the scattering intensity reconstructed from sets of 2D microdiffraction projections. Such analysis is non-destructive and provides high sensitivity (0.1% volume), high spatial resolution (µm3) and can be multi-modal providing quantitative information on the morphology, density, elemental composition or structure of materials. Additionally, we describe the development of in situ high-pressure–high-temperature microtomography using a new rotating Paris-Edinburgh cell (RoToPEC) combined with synchrotron radiation. The ability to fully rotate the sample chamber under load, overcomes the limited angular aperture of ordinary high-pressure cells for acquiring tomographic projections in both, full-field imaging or microdiffraction modes. This innovative method enables dynamic studies of materials under extreme pressure-temperature-stress conditions, impacting areas such as physics, chemistry, materials science or geology. The potential of this new experimental technique is demonstrated on the in situ investigation of of high-pressure–high-temperature polymerization of C60 . Keywords: C60, phase diagram, diffraction, microtomography, high-pressure–high-temperature
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Fang, Qingping [Verfasser]. "Investigation of in-situ electrode formation with respect to potential applications in intermediate temperature solid oxide fuel cells / Qingping Fang." Kiel : Universitätsbibliothek Kiel, 2010. http://d-nb.info/1019952288/34.
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Zamora, Torres David, and Felix Abeln. "Design of an In-situ cell, for hard X-ray spectroscopy of surfaces used in high-pressure and high-temperature experiments : Design av en In-situ cell för intensiv röntgenspektroskopi i högtryck- högtemperaturexperiment." Thesis, Malmö universitet, Institutionen för materialvetenskap och tillämpad matematik (MTM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-45607.
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This project analyzes how an in-situ cell can be developed to withstand high amounts of pressure and temperature of at least 100 bar and 500 °C. A theoretical prototype will be created as a product for Malmö University and other researchers to use or improve. To make this possible, the five step method was used to present a symmetric geometrical concept for the cell. That geometric concept was designed in PTC Creo (Version 6.0.2.0 & 7.0) in 3D and drawings in 2D. The programs GRANTA EduPack (Version 2020 \& Version 2019) along with Hephaestus was used to determine a material selection that will be able to tolerate temperature, pressure and be at least ten percent transparent, to be able for the X-ray to pass through the material and into the sample. The Finite Element Method (FEM) was used to ensure that the cell adheres to the set values of pressure and not cause a catastrophic failure. The result turn out to be a elliptical three part in-situ cell of boron carbide outer shell, a beryllium main dome and a stainless steel plate for the material sample to be on top. The Finite Element Method also showed that the designed in-situ cells meet the requirements and fulfills the goal and purpose. Further development of safety features and the equipment will be needed to minimise the risk of and dangers of beryllium dust.Detta projekt analyserar hur en in-situ cell kan utvecklas för att motstå höga mängder tryck och temperatur på minst 100 bar och 500 °C . En teoretisk prototyp kommer att skapas som en produkt för Malmö universitet och andra forskare att använda eller förbättra. För att göra detta möjligt användes femstegsmetoden för att presentera ett symmetriskt och geometriskt koncept för cellen. Det geometriska konceptet kommer att utformas 3-dimensionellt i PTC Creo (Version 6.0.2.0 7.0) och 2-dimensionella ritningar . GRANTA EduPack-programmen (Version 2020 \& Version 2019) tillsammans med Hephaestus användes för att bestämma ett materialval som kommer att kunna tolerera temperatur, tryck och vara minst tio procent transparent för att röntgenstrålningen ska kunna passera genom materialet och in i provet. Finite Element Method (FEM) kommer att användas för att säkerställa att cellen följer de inställda tryckvärdena och inte orsakar katastrofala fel. Resultatet visar sig vara en elliptisk tredelad in-situ cell av borkarbid som ett yttre skal, beryllium som huvudkupol och en rostfri stålplatta som underlag för materialprovet. Finite Element Method visade också att den designade in-situ-cellen uppfyller kraven och därför uppfyller målet och syftet. Detta innebär att vidareutveckling av säkerhetsfunktioner och utrustning kommer att behövas för att minimera risken för berusning från berylliumdammet.
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Saraiva, Letícia Oliveira. "Influência da umidade e temperatura intrabucais na resistência de união de sistemas adesivos convencionais de dois passos à dentina : estudo in situ." Programa de Pós- Graduação em Odontologia da UFBA, 2008. http://www.repositorio.ufba.br/ri/handle/ri/11031.
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O presente estudo teve como objetivos avaliar o efeito das condições de temperatura e umidade relativa intrabucais na resistência de união à dentina de dois sistemas adesivos convencionais de dois passos (Single Bond 2/SB2 e One Step Plus/OSP), e avaliar a umidade e a temperatura presentes nas regiões de incisivos e molares superiores. Sessenta fragmentos dentários foram esterilizados, fixados em moldeiras de acetato individualizadas, e posicionados in situ em um voluntário para serem restaurados com resina composta, sendo aleatoriamente divididos em seis grupos, de acordo com o sistema adesivo e com a condição de temperatura e umidade: G1 – SB2 na condição ambiental de um consultório odontológico; G2 – SB2 na condição da região de incisivos; G3 – SB2 na condição da região de molares; G4 – OSP na condição ambiental de um consultório odontológico; G5 – OSP na condição da região de incisivos e G6 – OSP na condição da região de molares. Em todas as condições, foram obtidas e registradas a temperatura e a umidade relativa do ar no momento e no local em que as restaurações foram produzidas, usando um termo-higrômetro digital. Após ensaio de microtração, os dados do teste de resistência de união foram submetidos à análise estatística (ANOVA - 2 fatores/ Teste de Tukey, α=5%) e os valores médios em MPa foram: G1 = 20,2 (7,6); G2 = 23,0 (6,5); G3 = 22,7 (6,0); G4 = 29,0 (5,8); G5 = 29,7 (4,9) e G6 = 27,7 (4,8). Os resultados demonstraram que os grupos que utilizaram o OSP (G4, G5 e G6) apresentaram médias semelhantes entre si (p=0,67) e maiores do que os grupos que utilizaram o SB2 (G1, G2 e G3) (p=0,001), também semelhantes entre si (p=0,67). Foi observado que as condições de temperatura presentes nas regiões intrabucais (incisivos e molares) foram semelhantes entre si, e maiores que a condição ambiental do consultório odontológico. A condição de umidade na região de molares foi superior à condição na região de incisivos, e esta foi maior do que a condição presente no ambiente do consultório odontológico. As condições de temperatura e umidade intrabucais não influenciaram a resistência de união dos sistemas adesivos simplificados à dentina. O sistema adesivo One Step Plus apresentou melhores resultados que o sistema Single Bond 2, independentemente das condições de umidade e temperatura.
Salvador
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Li, Hao. "Appproche structurale in situ des milieux fondus sous conditions extrêmes de température et de pression." Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE2054/document.
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La télédétection thermique en temps réel de systèmes volcaniques actifs est une technique cruciale pour comprendre le comportement et l'activité éruptive de corps magmatiques chauds. Cette technologie repose sur la détermination de l'émissivité thermique du magma, un paramètre permettant d'identifier la température du magma. Nous avons utilisé une méthode directe pour obtenir des spectres dans la plage de nombres d’onde allant de 400 à 13000 cm-1; d’échantillons naturels volcaniques (volcan Erebus et Teide) et synthétiques (avec différents éléments). Ces matériaux ont été chauffés de la température ambiante à 2000K avec un laser CO2 et les données ont été collectées pendant toute la phase de chauffage avec un spectromètre IRTF.Nos résultats indiquent que l’émissivité d’une roche magmatique est affectée par les changements de composition et l’histoire thermique. Les mesures d'émittance montrent le rôle important du fer et de la vitesse de refroidissement du magma sur la réponse spectrale des compositions de type phonolitique. Ces observations sont importantes, car une méconnaissance des valeurs d’émissivité engendre des erreurs sur la détermination de la température et, donc à une interprétation erronée de la rhéologie et de l'efficacité thermique du corps magmatiqueReal time thermal remote sensing of active volcanic systems is a crucial technique for understanding the behavior and eruptive activity of hot magmatic bodies. Such technology relies on determining the thermal emissivity of the magma, a parameter to identify the temperature of magma. We used a direct method to obtain a spectrum in the wavenumber range from 400 to 13000 cm-1; the natural (volcano Erebus and Teide) and synthetic samples were heated up from room temperature to 2000K with a CO2 laser and data were collected during all the heating stage with a FTIR spectrometer.Our results thus indicate that thermal emissivity of magmatic rock is affected by changes in composition and thermal history. The emissivity measurements show the important role of the iron and the cooling rate on the spectral response of the phonolite composition. These are important observations since different emissivity will lead to different temperature determinations and hence, an erroneous interpretation on the rheology and thermal efficiency of the magmatic body
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Crivoi, Maicon Rogerio. "Estudo in situ da deformação criogênica em aços inoxidáveis aisi 430 e AISI 316l utilizando radiação síncrotron." Universidade Estadual de Ponta Grossa, 2018. http://tede2.uepg.br/jspui/handle/prefix/2614.
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Dois aços inoxidáveis (AISI430 ferrítico e AISI316L austenítico) foram analisados por testes de tração uniaxial às temperaturas ambiente e criogênica, com taxas de deformação controladas para ambos os metais. Utilizou-se o equipamento Synchrotron Gleeble®, capaz de realizar medições de difração de raios X in situ, controlando a temperatura da amostra, a condição de tensão / tração, bem como a atmosfera da câmara e permitindo também a injeção de nitrogênio líquido diretamente sobre a amostra com excelente versatilidade e reprodutibilidade. Os testes foram realizados em um sistema de simulação termomecânica avançado, XTMS, localizado Centro Nacional de Pesquisa em Energia e Materiais - CNPEM - Campinas, SP, Brasil. A caracterização foi realizada por meio de imagens MEV e XRD in situ. As fotomicrografias e os resultados dos ensaios de tração mostram que o aço AISI 430 apresenta uma fratura dúctil à temperatura ambiente e fratura frágil a temperatura criogênica com aumento da resistência. Os resultados do aço AISI 316L evidenciam que o material tem uma fratura dúctil em ambas as condições. Para este mesmo metal, o alongamento a ambas as temperaturas foi praticamente o mesmo, mas a resistência à tração no ambiente criogênico foi muito maior. Este comportamento pode estar associado ao efeito TRIP, o que está de acordo com os dados XRD, uma vez que os picos de martensita α' induzida por deformação são evidenciados.
Two stainless steels (AISI430 ferritic and AISI316L austenitic) were analyzed by uniaxial tensile tests at room and cryogenic temperatures, with controlled strain rates for both metals. The Gleeble® Synchrotron system was used; it is capable to perform X-ray diffraction measurements in situ, controlling the sample temperature, controlling the stress / strain condition, as well as the chamber atmosphere, and also allowing the injection of liquid nitrogen directly into the sample with excellent versatility and reproducibility. The tests were performed in an advanced thermo mechanical simulation system, XTMS, located in the National Center for Research in Energy and Materials - CNPEM - Campinas, SP, Brazil. The characterization was performed by means of SEM images and in situ XRD. The photomicrographs and the results of the tensile tests show that AISI 430 steel presents a ductile fracture at room temperature and fragile fracture at cryogenic temperature with resistance increasing. The results of the AISI 316 L steel show that the material has a ductile fracture in both conditions. For this same metal, the elongation at both temperatures was practically the same, but the tensile strength in the cryogenic environment was much higher. This behavior may be associated with the TRIP effect, which agrees with the XRD data, since peaks of α’ strain induced martensite are evidenced.
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Herman, David M. "Fatigue Crack Growth and Toughness of Niobium Silicide Composites." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1228932584.
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Philippe, Julien. "Développement d'une presse portative pour les études in et ex situ sous conditions extrêmes de pression, température et déformation." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066008.
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Les hautes pressions sont précieuses à plusieurs disciplines scientifiques. Ce sera le cas dans cette thèse avec le développement d'un nouvel appareil permettant des possibilités inédites de tomographie et de déformation sous haute pression et haute température. Il apporte la possibilité de nouvelles études scientifiques dans les différents champs disciplinaires que sont les sciences de la Terre, la chimie mécanique, la physique des matériaux et la physique des liquidesHigh pressures are essential in several scientific field. This will be the case in this thesis with the development of a new device enabling new possibilities tomography and deformation under high pressure and high temperature. It brings the possibility of further scientific studies in the various disciplines that are Earth science, mechanical chemistry, physics of materials and liquids physics