Made available in DSpace on 2016-01-26T18:56:04Z (GMT). No. of bitstreams: 1 Gabriel Toledo.pdf: 1422789 bytes, checksum: bc7db628d8c25a109a8bfd6111bb65d4 (MD5) Previous issue date: 2015-06-03 / A growing body of evidence shows that plants anticipate responses of stress as a result of signals transmitted by neighboring plants. Transmit signal of lack of water between plants is a factor that adds complexity in the dynamics of populations, communities and ecosystems. Knowing more about this ability of plants can be useful for agriculture, mainly agro-forestry systems, and for reforestation efforts. By this way, this job was done to try to find more evidences of lack of water signaling transmission. To do this, stomata aperture related parameters (leaf temperature and leaf turgor pressure) were used to find possible effects of plants under lack of water on their neighborhood. Stomatal aperture, leaf temperature and leaf turgor pressure are parameters that indicates plant water status. Two experiments were done, one measured leaf temperature, and other leaf turgor pressure. Glycine max was used as experimental model. The seedlings roots were pruned, leaving only two roots similar per plant ("split-root"). The split-root plants were arranged in sets, with 4 pots and 3 plants (with each plant roots was divided into two pots). To induce sudden lack of water, mannitol solution was used (-2MPa), applied in the first pot. Leaf temperature was monitored by thermographic camera, and the leaf turgor was monitored by magnetic probe leaf turgor pressure (ZIM-probe). Data analysis was based on graphic interpretation. Leaf temperature variation was synchronous among plants of each set. The variation of leaf turgor in the day of induction to stress was completely changed from the previous day in half of sets. The sets which turgor variation was changed also showed sync. Environmental conditions, namely air temperature, and air relative humidity, were monitored and showed no correlations with the variation in leaf temperature or leaf turgor pressure. Sync indicates that there was communication. It is possible that lack of water communication among plants increases population stability. Stability in population can increase the fitness. So, it is possible that communication of lack of water among plants is a characteristic that has been shaped by natural selection, and distributed among taxa. / É crescente o número de evidências de que plantas antecipam respostas a estresses em consequência da sinalização emitida por plantas vizinhas. Transmitir sinal de falta de água entre plantas é um fator que acrescenta complexidade na dinâmica de populações, comunidades e ecossistemas. Conhecer mais sobre essa capacidade das plantas pode ser útil para agricultura, principalmente sistemas agro- florestais, e para esforços de reflorestamento. Sendo assim, este trabalho foi realizado para tentar encontrar mais evidências da transmissão de sinal de falta de água entre plantas. Para tanto, foram utilizados parâmetros relacionados à abertura estomática (temperatura e turgor foliar) para medir os efeitos de uma planta sob falta de água sobre plantas vizinhas. A abertura estomática, a temperatura e o turgor foliar são parâmetros indicativos do status hídrico. Foram realizados dois experimentos, um medindo a temperatura, outro a pressão de turgor foliar. Foi usado Glycine max como modelo experimental. As plântulas foram submetidas à poda, deixando-se apenas duas raízes semelhantes por planta ( split-root ). As mudas foram arranjadas em séries com 4 potes e 3 plantas (cada planta ficou com suas raízes divididas entre dois potes). Para induzir falta de água repentina, foi utilizada solução de manitol (-2 MPa), aplicado no primeiro pote. A temperatura foliar foi monitorada com uma câmera termográfica e o turgor foliar foi monitorado pela sonda magnética de pressão de turgor foliar (ZIM-probe). A análise dos dados foi feita em cima da interpretação dos gráficos. A variação de temperatura foliar aconteceu de forma sincrônica entre as plantas de cada série. A variação do turgor foliar foi totalmente alterada depois do estresse em metade das repetições. Nas séries onde o turgor foi alterado houve sincronia também. As condições ambientais de temperatura do ar, e de umidade relativa do ar, foram monitoradas e não mostram correlação com as variações de temperatura e turgor foliar. A sincronia indica que tenha havido comunicação. É possível que a comunicação de falta de água aumente a estabilidade de populações. Populações mais estáveis podem ter mais chances de deixar mais descendentes para próximas gerações. Assim, é provável que a capacidade de comunicar a falta de água a outras plantas seja uma característica moldada pela seleção natural e distribuída dentre os táxons.

Made available in DSpace on 2016-07-18T17:46:21Z (GMT). No. of bitstreams: 1 Gabriel Toledo.pdf: 1422789 bytes, checksum: bc7db628d8c25a109a8bfd6111bb65d4 (MD5) Previous issue date: 2015-06-03 / A growing body of evidence shows that plants anticipate responses of stress as a result of signals transmitted by neighboring plants. Transmit signal of lack of water between plants is a factor that adds complexity in the dynamics of populations, communities and ecosystems. Knowing more about this ability of plants can be useful for agriculture, mainly agro-forestry systems, and for reforestation efforts. By this way, this job was done to try to find more evidences of lack of water signaling transmission. To do this, stomata aperture related parameters (leaf temperature and leaf turgor pressure) were used to find possible effects of plants under lack of water on their neighborhood. Stomatal aperture, leaf temperature and leaf turgor pressure are parameters that indicates plant water status. Two experiments were done, one measured leaf temperature, and other leaf turgor pressure. Glycine max was used as experimental model. The seedlings roots were pruned, leaving only two roots similar per plant ("split-root"). The split-root plants were arranged in sets, with 4 pots and 3 plants (with each plant roots was divided into two pots). To induce sudden lack of water, mannitol solution was used (-2MPa), applied in the first pot. Leaf temperature was monitored by thermographic camera, and the leaf turgor was monitored by magnetic probe leaf turgor pressure (ZIM-probe). Data analysis was based on graphic interpretation. Leaf temperature variation was synchronous among plants of each set. The variation of leaf turgor in the day of induction to stress was completely changed from the previous day in half of sets. The sets which turgor variation was changed also showed sync. Environmental conditions, namely air temperature, and air relative humidity, were monitored and showed no correlations with the variation in leaf temperature or leaf turgor pressure. Sync indicates that there was communication. It is possible that lack of water communication among plants increases population stability. Stability in population can increase the fitness. So, it is possible that communication of lack of water among plants is a characteristic that has been shaped by natural selection, and distributed among taxa. / É crescente o número de evidências de que plantas antecipam respostas a estresses em consequência da sinalização emitida por plantas vizinhas. Transmitir sinal de falta de água entre plantas é um fator que acrescenta complexidade na dinâmica de populações, comunidades e ecossistemas. Conhecer mais sobre essa capacidade das plantas pode ser útil para agricultura, principalmente sistemas agro- florestais, e para esforços de reflorestamento. Sendo assim, este trabalho foi realizado para tentar encontrar mais evidências da transmissão de sinal de falta de água entre plantas. Para tanto, foram utilizados parâmetros relacionados à abertura estomática (temperatura e turgor foliar) para medir os efeitos de uma planta sob falta de água sobre plantas vizinhas. A abertura estomática, a temperatura e o turgor foliar são parâmetros indicativos do status hídrico. Foram realizados dois experimentos, um medindo a temperatura, outro a pressão de turgor foliar. Foi usado Glycine max como modelo experimental. As plântulas foram submetidas à poda, deixando-se apenas duas raízes semelhantes por planta ( split-root ). As mudas foram arranjadas em séries com 4 potes e 3 plantas (cada planta ficou com suas raízes divididas entre dois potes). Para induzir falta de água repentina, foi utilizada solução de manitol (-2 MPa), aplicado no primeiro pote. A temperatura foliar foi monitorada com uma câmera termográfica e o turgor foliar foi monitorado pela sonda magnética de pressão de turgor foliar (ZIM-probe). A análise dos dados foi feita em cima da interpretação dos gráficos. A variação de temperatura foliar aconteceu de forma sincrônica entre as plantas de cada série. A variação do turgor foliar foi totalmente alterada depois do estresse em metade das repetições. Nas séries onde o turgor foi alterado houve sincronia também. As condições ambientais de temperatura do ar, e de umidade relativa do ar, foram monitoradas e não mostram correlação com as variações de temperatura e turgor foliar. A sincronia indica que tenha havido comunicação. É possível que a comunicação de falta de água aumente a estabilidade de populações. Populações mais estáveis podem ter mais chances de deixar mais descendentes para próximas gerações. Assim, é provável que a capacidade de comunicar a falta de água a outras plantas seja uma característica moldada pela seleção natural e distribuída dentre os táxons.

Laminados compósitos com matrizes poliméricas, respectivamente termorrígida e termoplástica, reforçadas com fibras contínuas de carbono foram submetidos a impacto único transversal com diferentes níveis de energia. Os danos imprimidos aos materiais estruturais foram avaliados por termografia ativa infravermelha na modalidade transmissão. Em geral, os termogramas do laminado termoplástico apresentaram indicações mais claras e bem definidas dos danos causados por impacto, se comparados aos do compósito termorrígido. O aquecimento convectivo das amostras por fluxo controlado de ar se mostrou mais eficaz que o realizado por irradiação, empregando-se lâmpadas incadecentes. Observou-se também que tempos mais longos de aquecimento favoreceram a visualização dos danos. O posicionamento da face impactada do espécime, relativamente à câmera infravermelha e à fonte de calor, não afetou a qualidade dos termogramas no caso do laminado termorrígido, enquanto que influenciou significativamente os termogramas do compósito termoplástico. Os resultados permitiram concluir que a termografia infravermelha é um método de ensaio não-destrutivo simples, robusto e confiável para a detecção de danos por impacto inferior à 5 Joules em laminados compósitos poliméricos reforçados com fibras de carbono. / Continuous carbon fiber-reinforced thermosetting and thermoplastic composite laminates were exposed to single transversal impact with different energy levels. The damages marked to the structural materials were evaluated by active infrared thermography in transmission mode. In general, the thermoplastic laminate thermograms showed more clear and delineated damage indications when compared to the ones from thermosetting composite. The convective heating of the samples by controlled hot air flow was more efficient than via irradiation using lamp. It was also observed that longer heating times improved the damage visualization. The positioning of the specimen´s impacted face regarding the infrared camera and the heating source did not affect the thermo-imaging of thermosetting specimens, whereas it substantially influenced the thermograms of thermoplastic laminates. The results allow concluding that infrared thermography is a simple, robust and trustworthy methodology for detecting impact damages as light as 5 Joules in carbon fiber composite laminates.

The first part of the diploma thesis with name „Evaluation of dynamic damage of composite structure“ focuses on designing device for impact experiments and suitable laminate samples made from prepregs. The conditions and problems of impact tests are also demonstrated here. The second part of the thesis deals with non-destructive control of damaged specimens based on thermography. This is mainly the extent of defects in the impaired area and the evaluation of results using the pulse infrared thermography method. Finally, the relative deviation in the crack size comparison between the visual method and thermographic are compared. Consequently, the residual strength of the damaged samples against undamaged specimens are compared using bending tests.

The COVID-19 pandemic brought increased need for measuring human temperature. This thesis deals with solution of using low-cost thermal camera module FLIR Lepton 3.5 for measuring human forehead temperature and examines the real usability of this in terms of an accuracy. In the beginning, I describe various methods of measuring temperature and factors, which can influence the measurement. Subsequently, I examine various factors influencing human body and surface temperature. As of result of thesis is full design and implementation of thermal image system for temperature measurement, which I tested in different environmental conditions and compared its the precision against medical contactless infrared thermometer.

First part of this thesis describes possibilities of energy assessment of buildings, possibilities of using thermal imaging camera in civil engineering and using software solutions of energy assessment of buildings. Second part engages an energy assessment of administrative building of NEPA company in Brno and designes possibilities of improvements. Third part contains description of technical solution of the best improvement possibility.

This work deals with non-contact measurement of surface temperatures. The aim of the first part is to explain basic terms, principles and ways of measuring temperature. Furthermore, there is an overview of thermal imagining cameras usable in industry. In the practical part there is a theoretically suggested experiment, which monitors the dependence of the surface temperature on the size of the cross-section of the workpiece during the turning under unchanged cutting conditions. Experimental measurements are executed with using thermocamera ThermaCAM SC 200 and they are evaluated in software called Researcher.

Cette thèse s’inscrit dans le domaine de la fatigue des matériaux composites. Elle consiste à estimer les performances en fatigue d’un matériau composite thermoplastique tissé, en fibres de carbone et matrice PA66, par des essais d’auto-échauffement. Suite à une caractérisation de l’endommagement du matériau sous chargement monotone par un suivi acoustique, thermique et optique, une campagne d’essais de fatigue est réalisée sur deux configurations du matériau, à 0° et à 45°. Plusieurs méthodes de modélisation de la courbe S-N sont proposées, afin de déterminer la limite de fatigue du matériau. Il est montré que l’estimation de cette limite et de son intervalle de confiance est rendue difficile par la forte dispersion des données expérimentales. Des essais d’auto-échauffement sont alors réalisés, consistant à appliquer un chargement de fatigue sur un nombre de cycles limité, en incrémentant la contrainte maximale appliquée palier après palier. Des outils de traitement du signal sont développés afin de déterminer une contrainte seuil et son intervalle de confiance à partir de laquelle l’échauffement s’accélère. Cependant, cette contrainte seuil reste conservative par rapport à la limite de fatigue.Une autre approche est alors développée, consistant à suivre les amplitudes du signal thermique. De nouveaux outils de traitement du signal sont développés, dans le but de réaliser des cartographies de l’éprouvette à partir des amplitudes des harmoniques. Il est alors montré qu’il est possible d’obtenir les mêmes courbes que les courbes d’auto-échauffement en réalisant un suivi des amplitudes des harmoniques, et ce pour une centaine de cycles seulement. Un nouveau protocole d’essai d’auto-échauffement est alors mis en place, fondé sur une centaine de paliers de quelques centaines de cycles seulement, permettant d’aboutir à un suivi des harmoniques avec des courbes finales quasi-continues en un minimum de temps. / This thesis is part of the study on the fatigue of composite materials. It consists in estimating the fatigue performance of a thermoplastic composite woven material, made of carbon fibres and PA66 matrix, by self-heating tests. Following a characterization of the damage to the material under monotonous loading by acoustic, thermal and optical monitoring, a fatigue test campaign is carried out on two material configurations, at 0° and 45°. Several methods for modelling the S-N curve are proposed to determine the fatigue limit of the material. It is shown that the estimation of this limit and its confidence interval is complicated by the large dispersion of experimental data. Self-heating tests are then carried out, consisting of applying a fatigue load over a limited number of cycles, increasing the maximum stress applied step by step. Signal processing tools are developed to determine a threshold stress and its confidence interval at which the heating accelerates. However, this threshold stress remains conservative in comparison to the fatigue limit. Another approach is then developed, consisting in monitoring the amplitudes of the thermal signal. New signal processing tools are being developed to map the specimen from the harmonic amplitudes. It is then shown that it is possible to obtain the same curves as the selfheating curves by monitoring the amplitudes of the harmonics, and this for only a hundred cycles. A new self-heating test protocol is then implemented, based on a hundred steps of only a few hundred cycles, allowing harmonics to be monitored with almost continuous final curves in a minimum of time.

abstract: Granular material can be found in many industries and undergo process steps like drying, transportation, coating, chemical, and physical conversions. Understanding and optimizing such processes can save energy as well as material costs, leading to improved products. Silica beads are one such granular material encountered in many industries as a catalyst support material. The present research aims to obtain a fundamental understanding of the hydrodynamics and heat transfer mechanisms in silica beads. Studies are carried out using a hopper discharge bin and a rotary drum, which are some of the most common process equipment found in various industries. Two types of micro-glass beads with distinct size distributions are used to fill the hopper in two possible packing arrangements with varying mass ratios. For the well-mixed configuration, the fine particles clustered at the hopper bottom towards the end of the discharge. For the layered configuration, the coarse particles packed at the hopper bottom discharge first, opening a channel for the fine particles on the top. Also, parameters such as wall roughness (WR) and particle roughness (PR) are studied by etching the particles. The discharge rate is found to increase with WR, and found to be proportional to (Root mean square of PR)^(-0.58). Furthermore, the drum is used to study the conduction and convection heat transfer behavior of the particle bed with varying process conditions. A new non-invasive temperature measurement technique is developed using infrared thermography, which replaced the traditional thermocouples, to record the temperatures of the particles and the drum wall. This setup is used to understand the flow regimes of the particle bed inside the drum and the heat transfer mechanisms with varying process conditions. The conduction heat transfer rate is found to increase with decreasing particle size, decreasing fill level, and increasing rotation speed. The convection heat transfer rate increased with increasing fill level and decreasing particle size, and rotation speed had no significant effect. Due to the complexities in these systems, it is not always possible to conduct experiments, therefore, heat transfer models in Discrete Element Method codes (MFIX-DEM: open-source code, and EDEM: commercial code) are adopted, validated, and the effects of model parameters are studied using these codes. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2020

Several applications, including those in the energy sector that require high thermal efficiency, such as those in the solar energy industry, require a careful thermal analysis of heat exchange components. In this regard, thermal resistance is a major cause of exergy destruction and must be minimised as much as possible, but also adequately designed. In the past, a number of correlations have been developed to predict heat transfer coefficients in compact heat exchangers. The designers of such heat exchangers often exploit the development of thermal boundary layers to achieve higher overall efficiency due to increases in local heat transfer coefficients. However, most of the correlations that have been developed for heat exchangers neglect the specific effect of the thermal boundary layer development in the inlet region, and instead only offer effective average heat transfer coefficients, which most users assume to be constant throughout the heat exchanger. This is often an over-simplification and leads to over-designed heat exchangers. In this study, focus is placed on annular flow passages with uniform heating on the inner wall. This geometry has many applications. This study aims to collect experimental heat transfer data for water at various flow rates and inlet geometries, to process the data and determine local and overall heat transfer coefficients, and to develop an improved local heat transfer coefficient correlation. Experimental tests were performed on a horizontal concentric tube-in-tube heat exchanger with a length of 1.05 m and a diameter ratio of 0.648. The surface of the inner tube was treated with thermochromic liquid crystals (TLCs), which allowed for high-resolution temperature mapping of the heated surface when combined with an automated camera position system in order to determine local heat transfer coefficients. Conventional in-line and out-of-line annular inlet configurations were evaluated for Reynolds numbers from 2 000 to 7 500, as well as the transition from laminar to turbulent flow for a single in-line inlet configuration. It was found that the local heat transfer coefficients were significantly higher at the inlets, and decreased as the boundary layers developed. With the high resolution of the results, the local heat transfer coefficients were investigated in detail. Local maximum and minimum heat transfer coefficients were identified where the thermal boundary layers merged for high turbulent flow cases. The annular inlet geometries only influenced the heat transfer for Reynolds numbers larger than 4 000, for which larger inlets are favoured. Out-of-line inlet geometries are not favoured for heat transfer. A new heat transfer correlation was developed from the experimental data, based on an existing heat transfer correlation for turbulent flow in an annular flow passage, considering the boundary layer development. The new correlation estimated the area-weighted heat transfer coefficients within 10% of the experimental data and closely followed trends for local heat transfer coefficients. / Dissertation (MEng)--University of Pretoria, 2017. / Mechanical and Aeronautical Engineering / MEng / Unrestricted