A medida do teor de umidade de materiais resulta em ganhos econômicos e ambientais ao possibilitar o controle preciso da secagem de produtos agrícolas, de processos de cura e armazenagem, e reduzir perdas de material e consumo de energia. Tal medida pode ser feita através da interação de ondas eletromagnéticas nas frequências de micro-ondas. Apresenta-se o desenvolvimento histórico e o estado da arte dessa área da metrologia que é conhecida por aquametria por micro-ondas. Detalha-se o comportamento das ondas eletromagnéticas em dielétricos, o modelo de espalhamento nas interfaces das amostras, a relação entre a permissividade complexa e a umidade, métodos para a determinação da permissividade, instrumentos, sistemas e aspectos metrológicos da cadeia de medição para espectroscopia dielétrica. Dois novos métodos, com equações explícitas originais para a determinação da permissividade são obtidos. As novas equações resultam em incerteza menor que os métodos clássicos. Uma nova metodologia, através do método de Monte Carlo, é empregada para a avaliação das mesmas. Conclui-se que o desenvolvimento da aquametria passa, necessariamente, pelo aperfeiçoamento dos instrumentos e métodos para determinação da permissividade dos materiais. / The measurement of moisture content of materials results in economic and environmental gains. Monitoring drying and curing of materials prevents loss of products and waste of energy. This can be done through the interaction of electromagnetic waves at microwave frequencies. This dissertation presents the historical development and the state-of-the-art in aquametry, the behavior of electromagnetic waves in dielectrics, sample interface scattering model, the relationship between the complex permittivity and moisture, methods for determining permittivity, instruments and metrological aspects of the measurement chain, and some instruments for dielectric spectroscopy. Two new methods, capable of providing explicit equation for the permittivity, are obtained and the Monte Carlo method is applied to determine their uncertainty. The new equations have lower uncertainty than the classic methods. The general conclusion is that the development of instrumentation and techniques in aquametry must be based in improvements in permittivity measurement.

A medida do teor de umidade de materiais resulta em ganhos econômicos e ambientais ao possibilitar o controle preciso da secagem de produtos agrícolas, de processos de cura e armazenagem, e reduzir perdas de material e consumo de energia. Tal medida pode ser feita através da interação de ondas eletromagnéticas nas frequências de micro-ondas. Apresenta-se o desenvolvimento histórico e o estado da arte dessa área da metrologia que é conhecida por aquametria por micro-ondas. Detalha-se o comportamento das ondas eletromagnéticas em dielétricos, o modelo de espalhamento nas interfaces das amostras, a relação entre a permissividade complexa e a umidade, métodos para a determinação da permissividade, instrumentos, sistemas e aspectos metrológicos da cadeia de medição para espectroscopia dielétrica. Dois novos métodos, com equações explícitas originais para a determinação da permissividade são obtidos. As novas equações resultam em incerteza menor que os métodos clássicos. Uma nova metodologia, através do método de Monte Carlo, é empregada para a avaliação das mesmas. Conclui-se que o desenvolvimento da aquametria passa, necessariamente, pelo aperfeiçoamento dos instrumentos e métodos para determinação da permissividade dos materiais. / The measurement of moisture content of materials results in economic and environmental gains. Monitoring drying and curing of materials prevents loss of products and waste of energy. This can be done through the interaction of electromagnetic waves at microwave frequencies. This dissertation presents the historical development and the state-of-the-art in aquametry, the behavior of electromagnetic waves in dielectrics, sample interface scattering model, the relationship between the complex permittivity and moisture, methods for determining permittivity, instruments and metrological aspects of the measurement chain, and some instruments for dielectric spectroscopy. Two new methods, capable of providing explicit equation for the permittivity, are obtained and the Monte Carlo method is applied to determine their uncertainty. The new equations have lower uncertainty than the classic methods. The general conclusion is that the development of instrumentation and techniques in aquametry must be based in improvements in permittivity measurement.

- Einleitung: Projektvorstellung 3D – Saat - Material und Methode zur Einflussermittlung von Bodenparametern auf die Ergebnisse der Feuchtemessung - Präsentation und Diskussion der Ergebnisse - Zusammenfassung und Ausblick

Timber drying is one of the most important processes whenmanufacturing sawn timber products. The drying processinfluences deformations, surface checking, discoloration andhence, the product quality and the manufacturing costs.Research in this field is of great importance for the woodindustry since the industrial drying process always needs to beimproved as market demands increases and new wood products aredeveloped. The aim of the present thesis was to investigate themoisture transport behaviour in wood based on measurementsduring drying from fresh condition down to end use moisturecontent. The behaviour near the surface interface has beenspecifically investigated since it is of great importance forthe theoretical description of the drying process. Furthermore,studies based on measurements in the wood surface layer duringdrying are not easy to find in the literature. The reason forthat is probably that it is very difficult to make accuratemoisture measurements with high spatial or temporal resolutionwithout disturbing the drying process. Measurements of moisture content profiles in Scots pineheartwood and sapwood during drying have been performed byusing three different methods. The first was a destructivemethod where the wood samples are sliced with a knife intoseveral smaller pieces. The moisture content in each piece wasdetermined with the dry weight method. The second method usedis non-destructive and it utilises a medical CT-scanner thathas been adapted for drying experiments. The samples are driedin-situ the scanner through the whole experiment. TheCT-scanner measures density and the moisture content arecalculated according to existing methods developed by otherscientists. The third method was also non-destructive and itutilises a Magnetic Resonance Imaging, MRI, technique. Withthis technique the amount of water in the wood sample ismeasured directly even though it has to be calibrated tomoisture content. The surface emission factor, S, or surface resistance, 1/S,has been studied by performing sorption experiments with MDF ina narrow moisture content range. The experiment was evaluatedusing a simple diffusion model that includes a surface emissionfactor S. The experimental result was compared with resultscalculated using well established boundary layer theories. Measurements of moisture content profiles in the wood bulkshowed an expected Fickian behaviour at moisture contents belowthe fibre saturation point. Above the fibre saturation pointalmost flat moisture profiles were observed. This behaviour wasnot expected and it is not possible to simulate this behaviourwith the existing drying models since they usually assume thatthere is a gradient in the moisture profile over the wholemoisture content range. From the moisture profiles thediffusion coefficients were determined over a moisture contentranging from 8 to 30%. The values for heartwood and sapwood areapproximately equal in radial and tangential direction tograin. Furthermore, the diffusion values in longitudinaldirection are much higher as expected. The sorption experiments with MDF gave a greater surfaceresistance compared with the calculation that was based onboundary layer theory. The ratio was three or higher. Thisimplied that there was a greater resistance in the surfacelayer. In addition, this was not well described in theliterature even though a few recent published studiesexist. High resolution measurements in the surface layer of woodshowed behaviour similar to that observed in the bulk wood. Theresults showed the very early development of a dry zone closeto the surface interface. In that zone or shell the moisturecontent was below the FSP even though the bulk moisture contentwas far above the FSP. At the end of the experiments themoisture content in the surface layer (0–300 µm)nearly reached the equilibrium moisture content even though thebulk moisture content still was much higher. Keywords:Computer tomography, Diffusion, Magneticresonance, Moisture measurements, Moisture profiles, Surfaceemission, Wood drying / <p>NR 20140805</p>

No description available.

A detailed design was developed of an apparatus to measure moisture transfer in porous materials. The apparatus is to be used to collect data to aid in the development of mathematical models which accurately describe this phenomena. The apparatus consists of dual environmental chambers between which a specimen material is sealed. The temperature of each chamber is controlled separately allowing nonisothermal test conditions. The relative humidity is maintained without the use of saturated salt solutions. The moisture transfer rate is measured by periodically weighing a desiccant column used to absorb moisture as result of diffusion across the specimen. The apparatus was built and used to verify a heat transfer model written to predict its thermal characteristics. The chamber temperature capabilities are 5°C to 60°C with up to a 20°C temperature difference across the specimen. The relative humidity limits are based on the heat transfer into or out of the system. High relative humidities (75 to 85 percent) are possible at chamber temperatures close to ambient, but decrease sharply at the extremely high or low temperatures and during nonisothermal operation. The apparatus maintains a constant temperature within ±0.4°C of the setpoint when subjected to varying ambient temperatures. The spatial temperature variation close to the sample (within 25 mm) is within approximately ​​​​±1°C of the average chamber temperature. The relative humidity can be manually controlled to within ±.7 percent RH. Automated control, complicated by a response lag, was within ±1 percent RH. / Master of Science

An experimental investigation was carried out to determine the feasibility of using thermal conductivity measurements to detect moisture concentrations in a highly porous glass fiber insulation. A new technique employing thermistor probes was used to measure thermal conductivity over a range of low moisture contents. The results indicate that the material's thermal conductivity is a strong nonlinear function of the moisture concentration. The sensitivity of the moisture content to thermal conductivity is greatest for moisture contents less than 25 per cent for the material tested. A numerical procedure for predicting the temperature and moisture distributions in a highly porous material is detailed. / Ph. D.

As ornamental container nurseries face diminishing water allocations, many are looking to automated irrigation solutions to increase their water application efficiency. This thesis presents the findings of a study conducted at a commercial container nursery to determine 1) whether a capacitance or load cell sensor was better suited for monitoring volumetric water content in the substrate; 2) if the actual irrigation distribution conformed to the expected pattern, how uniform were the weights of plants, and how these combined with plant canopy affected the leaching fraction; and 3) the reliability of the wireless network used to transmit the data to a central database. It was found that 1) the load cells outperformed the capacitance-based sensors because the load cells took an integrated measure; 2) the actual irrigation pattern followed the expected pattern, the variation of irrigation sections were low (C.V. = 0.06) and similar (C.V. ranging from 0.029 to 0.12), and unpruned plant canopies produced greater leaching fraction than pruned canopies (P < 0.18); and 3) wireless network transmission reliability was low (75.2%), suggesting that the system was not suitable for real-time irrigation control, but was sufficient for calculating irrigation length and monitoring net effective irrigation application and evapotranspirative consumption. / Graduation date: 2012

No description available.

In the past, derivative-based optimization algorithms have not frequently been used to calibrate conceptual rainfall -riff (CRR) models, partially due to difficulties associated with obtaining the required derivatives. This research applies a recently- developed technique of analytically computing derivatives of a CRR model to a complex, widely -used CRR model. The resulting least squares response surface was found to contain numerous discontinuities in the surface and derivatives. However, the surface and its derivatives were found to be everywhere finite, permitting the use of derivative -based optimization algorithms. Finite difference numeric derivatives were computed and found to be virtually identical to analytic derivatives. A comparison was made between gradient (Newton- Raphsoz) and direct (pattern search) optimization algorithms. The pattern search algorithm was found to be more robust. The lower robustness of the Newton-Raphsoi algorithm was thought to be due to discontinuities and a rough texture of the response surface.