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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Evaporation of single drops in superheated vapor

Trommelen, August Maris, January 1968 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
62

Potential evapotranspiration estimates by the Penman and Thornthwaite methods

Pelton, W. L. January 1958 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1958. / Typescript. Abstracted in Dissertation abstracts, v. 19 (1958) no. 4, p. 614-615. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 63-65).
63

Efeito de diferentes tempos e temperaturas de volatilização de solventes sobre o grau de conversão e as propriedades mecânicas de sistemas adesivos dentinários / Effect of different volatilization times and temperatures of solvents on degree of conversion and mechanical properties of dentin bonding systems

Araújo, Larissa Sgarbosa Napoleão de, 1984- 18 August 2018 (has links)
Orientador: Giselle Maria Marchi Baron / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-18T10:15:57Z (GMT). No. of bitstreams: 1 Araujo_LarissaSgarbosaNapoleaode_M.pdf: 3474527 bytes, checksum: 9bfdeda78eb0f2e753e727642f5d8c80 (MD5) Previous issue date: 2011 / Resumo: O objetivo deste estudo foi avaliar a influência de diferentes tempos (5s, 10s, 20s) e temperaturas (±23º, ±40ºC) para volatilização de sistemas adesivos [Excite (EX) e Single Bond 2 (SB)] sobre o grau de conversão (GC), resistência coesiva (RC), módulo de elasticidade (ME) e resistência à flexão (RF). A fonte de luz LED - Elipar Free Light 2 foi utilizada para fotoativação das amostras por 20 s (1100 mw/ cm2). Para a análise da RC, RF e ME cada corpo de prova foi confeccionado a partir de uma matriz de silicone por adição em forma de barra (2x1x7mm). Sobre a matriz, foram dispensados 10 ?L de adesivo após receberem leve jato de ar com tempo e temperatura variando de acordo com cada grupo, e fotoativados por 20s. Para análise de RC (n=10), os corpos de prova foram fixados à Máquina de Ensaio com célula de carga de 200N, e para RF e ME (n=5) com carga de 50N, ambos realizados a 0,5mm/ min, até a ruptura da amostra. Para mensuração do GC (n=5) foram dispensados 3?L de adesivo sobre o cristal e utilizada espectroscopia de transmissão infravermelha de Fourier (FTIR) na faixa de 1665 a 1580 cm-1. Os dados foram submetidos a análise de variância 3 fatores e teste de Tukey (p< 0,05). Para EX e SB, a temperatura de ±40ºC resultou em maior RC em todos os tempos de volatilização. Os maiores valores de RC foram observados no tempo de 20s, seguidos dos tempos de 10s e 5s, respectivamente. Maiores valores de RC foram encontrados para o adesivo EX comparativamente ao SB. Para GC não houve diferença estatisticamente significante para EX entre as temperaturas e tempos de volatilização estudados. Para SB, maiores valores de GC foram obtidos com a temperatura de ±40ºC com exceção do grupo volatilizado por 20s, que não diferiu estatisticamente da temperatura de ±23ºC. EX apresentou maiores valores de GC que SB, independente de tempo e temperatura de volatilização. Com relação ao ME, para EX não houve diferença estatisticamente significante entre os tempos e as temperaturas de volatilização. Apenas para SB, a temperatura de ±40ºC promoveu aumento no ME e, entre os tempos de volatilização não houve diferença estatisticamente significante. De acordo com o resultado da análise da RF, para EX não foi observado efeito estatisticamente significante entre as temperaturas de volatilização estudadas. A volatilização à temperatura de ±40ºC de SB resultou em melhor desempenho na RF. Para tempo de volatilização, tanto para SB quanto para EX, independente da temperatura de volatilização, os tempos de 20 e 10s não diferiram estatisticamente entre si e foram maiores do que 5s. Os resultados deste estudo indicam que há uma superioridade do adesivo à base de etanol sobre os que associam etanol e água. De modo geral, a volatilização por 20s elevou o desempenho dos sistemas adesivos testados. A volatilização com altas temperaturas dos sistemas adesivos avaliados, elevou o GC bem como as propriedades mecânicas dos mesmos. O ar aquecido elevou a resistência coesiva dos adesivos à base de etanol / Abstract: The aim of this study was to evaluate the influence of different times (5s, 10s, 20s) and temperatures (±23º, ±40ºC) for volatilization of various adhesive systems [Excite (EX) and Single Bond 2 (SB)] on the degree of conversion (DC), cohesive strength (CS), modulus of elasticity (ME) and the flexural strenght (FS). The light curing unit Elipar Free Light 2- LED was used for curing the samples by 20s. For the analysis of CS, FS and ME each specimen was made from a silicone matrix addition with the stick format (2x1x7mm). On the matrix were dispensed 10 ?L of adhesive after receiving gentle air with time and temperature varying according to each group, and were cured for 20s. For analysis of CS (n=10), the specimens were fixed to the Testing Machine with a load cel of 200N, and for FS and ME (n= 5) with a load of 50N, both held at 0.5 mm/min until failure of the sample. For measurement of DC (n = 5), after volatilization, were dispensed 3 ?L of adhesive on the crystal and used Fourier Transform Infrared transmission Spectroscopy (FTIR) in the range from 1665 to 1580 cm-1. The data were subjected to three factors ANOVA and Tukey test (p <0.05). For EX and SB, the temperature of ± 40°C resulted in higher CS at all times of evaporation. The highest values of CS were observed in 20s, followed by times of 10s and 5s, respectively. Higher values of CS were found for the adhesive EX compared to SB. For GC there was no statistically significant difference for EX between the times and temperatures volatilization studied. For SB, higher values of DC were obtained with a temperature of ±40 ºC with the exception of the group volatilized of 20s, that did not differ from temperature of ±23ºC. EX presented higher values of DC followed by SB, regardless of time and temperature of volatilization. Regarding the ME, to EX, there was no statistically significant difference between the times and temperatures of volatilization. Just to SB, the temperature of ±40°C promoted an increase in the ME, and between times of volatilization there was no statistically significant difference. According to the outcome of the FS, for EX was not observed statistically significant effect between the temperatures of volatilization studied. The temperature of ± 40 ºC of SB resulted in better performance in FS. On the time of volatilization for both SB and EX, independent of volatilization temperature, the times of 20 and 10s did not differ statistically and were higher than 5s. The results of this study indicate that there is a superiority of ethanol-based adhesive on those where there is the association of ethanol and water. In general, the volatilization for 20s increased the performance of adhesive systems evaluated. Volatilization at high temperature adhesive systems based on water and ethanol, has raised its DC and the mechanical properties of them. The heated air increased CS of adhesives based on ethanol / Mestrado / Dentística / Mestre em Clínica Odontológica
64

Electronic data acquisition system for the energy balance/Bowen ratio measurement of evaporation

Tang, Paul Wing Kay January 1976 (has links)
A system for the energy balance/Bowen ratio measurement of evaporation was designed and tested. The system produces eight channels of integrated meteorological data for evaporation calculation. The various voltages required to operate the meteorological sensors are produced internally by a bank of regulated power supplies. Control signals are generated by a quartz crystal -clock. The data in a selected channel and the time of day are displayed on the front panel of the data logger. All eight channels of data and the time are printed on a paper tape every 15 or 30 minutes as desired. The output circuitry was designed to be compatible with microprocessor components. The data logger is contained in a 60 cm x 50 cm x 40 cm metal cabinet and is powered by 110 VAC. The laboratory and field tests of the system were successful. / Land and Food Systems, Faculty of / Graduate
65

A study of evaporation from a short grass surface.

Kevan, Simon Michael January 1973 (has links)
No description available.
66

Effect of particles on evaporation of droplet containing particles

Wei, Yan 01 January 2015 (has links)
The evaporation of droplet containing insoluble particles has grown into an active area of research due to the needs for nanofluids for applications in heat transfer, combustion, and manufacturing desired micro/nano particles in the pharmaceutical industry. The evaporation of droplets containing particles involves complicated multiphase heat and mass transport. The evaporation process consists of two stages: the first stage consists of evaporation until a shell of particle forms or when the solid to liquid ratio is sufficiently large and the second stage, where the droplet size is commonly assumed to be unchanged. The dissertation investigates the evaporation kinetics in the first stage. An experimental setup based on electrodynamic balance (EDB) is built to allow the observation of evaporation of a free standing micro size droplet. Besides experimental design, a novel theoretical model is developed to first describe the morphological evolution process in the absence of internal convection. The model accounts for the effect of particles at the droplet surface on the diffusion of liquid vapor. The gradually increasing particle number at the droplet surface reduces the area for evaporation, leading to reduction in evaporation rate in the first drying stage, contrary to previous assumptions. The evaporation in the first stage is controlled by Pe (defined as the ratio of droplet evaporation rate to the particle diffusion rate) and particle properties such as wettability. For large values of Pe, the particles concentration is high near the droplet surface, leading to the change of evaporation rate. For small values of Pe, the effect of particles on the evaporation rate of droplet in the first drying stage is small because particles are allowed sufficient time to redistribute within the droplet. The model analysis also reveals that particle wettability is an important factor affecting the first drying stage. For hydrophilic particles, the contact angle of the particles at the droplet surface is small, leading to small change of evaporation in the first stage. For the hydrophobic particles that have large contact angles, the change of evaporation rate in the first drying stage is larger. The evaporation model that accounts for the internal convection is also used to describe the evaporation process. In this model, the evaporation behavior during the first stage is controlled by the particle mobility, initial particle concentration, and droplet recession/evaporation rate. For particles with high mobility, the particle distribution within the droplet tends to be smooth. The effect of convection flow on the particles distribution becomes stronger as particle mobility decreases. Once the particles mobility is decreased to a limit at which the surface particle density is only controlled by the internal flow and the evaporation process is independent of the particles mobility. For a given internal flow field and a specific particles mobility, the duration of the first stage and the final dry particle size are both controlled by the initial particle concentration. A smaller/larger initial particle concentration results in a longer/shorter first stage and smaller/larger dry particle.
67

Effect of environmental factors and water-table depth on evaporation rates from soils in the presence of water table /

Saxena, Gobind Saran January 1969 (has links)
No description available.
68

Comparisons of evaporation and evapotranspiration at Ebini

Fraser, Duncan. January 1974 (has links)
No description available.
69

Factors contributing to evaporation over the North Atlantic.

Chisholm, William Joseph January 1966 (has links)
No description available.
70

Séchage de fluides complexes en géométrie confinée

Daubersies, Laure Sylvie Véronique 28 September 2012 (has links)
Dans ce travail de thèse, nous avons développé deux méthodologies permettant d'acquérir rapidement et facilement des propriétés physico-chimiques, cinétiques et thermodynamiques de fluides complexes. Nous nous sommes focalisés sur le rôle de la concentration sur ces propriétés. Les deux méthodes développées sont basées sur la concentration en continu d'une solution aqueuse par évaporation contrôlée du solvant. Le premier outil est une goutte de quelques microlitres confinée entre deux plaques dont la hauteur est de 100µm. Dans cette géométrie à deux dimensions, l'évaporation est entièrement décrite par un modèle que nous avons développé. L'observation du séchage de la goutte couplée à des mesures locales de concentration par spectroscopie Raman, permet d'accéder quantitativement au diagramme de phase d'une solution de copolymères, et de mesurer l'activité ainsi que d'estimer le coefficient d'interdiffusion de la solution. Le second outil est une puce microfluidique permettant de concentrer des solutions aqueuses grâce à la pervaporation de l'eau à travers une membrane. Cet outil permet avec quelques microgrammes de soluté, de bâtir un gradient de concentration stationnaire le long d'un microcanal. Les techniques de spectroscopie Raman et de diffusion des rayons X aux petits angles permettent à nouveau de mesurer des propriétés physico-chimiques de la solution mais également de mettre en évidence le caractère discontinu du coefficient d'interdiffusion en fonction de la concentration, dépendant des mésophases présentes. / In this work, we developed two methods in order to access rapidly and easily physico-chemical, thermodynamic and kinetic properties of complex fluids. We focused on the role of the concentration on these properties. The two methods that we developed are based on the continuous concentration of an aqueous solution thanks to the evaporation of the solvent. The first tool is a microliter droplet confined between two circular plates with a cell height of about 100 µm. Within this two dimensional cylindrical geometry, the evaporation of the droplet is totally described by a model that we developed. The observation of the droplet evaporation combined to local Raman spectroscopy measurements permits us to build a quantitative phase diagram, to measure the activity of the solution and to estimate its mutual diffusion coefficient. The second tool is a microfluidic chip in which water is removed through a thin membrane. This device permits us to build with a few micrograms of solutes a stationary concentration gradient along a microchannel. Raman confocal spectroscopy and small angle X-ray scattering give access to the quantitative phase diagram and also permit to evidence that the mutual diffusion coefficient is discontinuous at some of the phase boundaries.

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