Thesis (M.S.)--University of Michigan, 1976.

M.Ing. / Please refer to full text to view abstract

A 10 GHz microwave bridge measurement system has been developed to automatically measure the electromagnetic field parameters transmitted through a dielectric material. These parameters are used to calculate the complex dielectric constant with the free-space transmission technique. The system is used to measure the field parameters transmitted through dimension lumber and a correlation is made with two strength determining factors of lumber: specific gravity and moisture content. Hemlock and Douglas Fir wood samples were tested and a grading technique was implemented. The system is capable of estimating the specific gravity to ±0.05 accuracy and the moisture content to ±3.0% accuracy. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Digitized by Kansas Correctional Industries

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (M. Sc. Agr.)--University of Sydney, 1999. / Title from title screen (viewed Apr. 21, 2008). Submitted in fulfilment of the requirements for the degree of Master of Science in Agriculture to the Dept. of Agricultural Chemistry & Soil Science, Faculty of Agriculture. Includes bibliography. Also available in print form.

The first objective of this problem - thorough literature review - was conducted on all available references concerning humidity measurement, and visits were made to the American Instrument Company in Silver Springs, Maryland, and the National Bureau of Standards. The survey evaluated the instruments in use today and also explored many of the ideas and concepts that have been suggested in past years as possible means for humidity measurement. A summation of the survey indicated that the electric hygrometer with a ceramic element was a good basic theory for a humidity instrument, but still required development before it,would be of any practical use. The second objective - development of a useful hygrometer - was directed towards the development of the electric hygrometer using a ceramic element. The study that resulted included the evaluation of two methods for determining the change of resistance of the ceramic element, as well as a preliminary investigation of the characteristics of a ceramic element when employed as the sensing element for an electric hygrometer. The element intended for the initial tests, a porous ceramic containing mostly aluminum oxide, was the only material tested, but the tests included elements of the pure ceramic material and the same material after it was soaked in a saturated solution of lithium chloride. With the instruments used, the indications were that both elements were suited for determining the high humidities. The pure element had a lower limit of 50 percent relative humidity, and the coated element a lower limit of 20 percent. Two instruments were used for indicating the change of relative humidity. A vacuum tube voltmeter type instrument was tested, but found unsatisfactory due to variations of readings under the same conditions, drifting of the zero set, and excessive fluctuations of the indicating meter. The other instrument or method used was to apply an A-C voltage across the element, and to measure the resulting current flow. Because the current was maintained above 1 milliampere, heating of the element was caused, resulting in a change of element resistance. However, results with this instrument were sufficient to establish a calibration curve for the apparatus. A comparison of this device and a psychrometer indicated the usefulness of such an instrument, but confirmed that the development was not complete. The overall result of the research indicates that the selection of the ceramic sensing element for an electric hygrometer has merit, but more development is necessary. Two phases of any future work on the problem should be the development of the indicating instrument, and the selection and design of the sensing element. The need for a satisfactory instrument still exists, and the successful development of the type instrument described herein, would undoubtedly meet the requirements. / Master of Science

A madeira quando seca é um excelente isolante elétrico, porém quando a umidade da madeira aumenta, essa característica diminui fazendo com que esta passe a conduzir a corrente elétrica. A determinação do teor de umidade permite um controle do custo de produção e qualidade da madeira, além de facilitar a utilização de tratamentos preservativos e pintura. O método de determinação do teor de umidade com o uso de estufa é o método mais exato, e por esta razão é utilizado como padrão para calibrar outras técnicas. Por outro lado, a verificação do teor de umidade por meio da estufa é muito demorado e danifica parte do componente a ser analisado. O objetivo deste trabalho é propor uma metodologia para calibrar medidores elétricos de umidade, utilizando espécies de dicotiledôneas nativas e coníferas de florestamento. Na experimentação realizada foi possível constatar que apesar da menor precisão na determinação de teores de umidade, o método que utiliza medidores de umidade do tipo resistência, permite com algumas correções, a obtenção de valores confiáveis para o controle de umidade de peças de madeira serrada. Para isso foram desenvolvidas expressões obtidas por meio de análise de regressão linear que possibilitam fazer as correções necessárias nas leituras realizadas com o medidor elétrico do tipo resistência. / Wood when dry is an excellent electric insulating material. However when the moisture content of wood increases, that feature decreases, which makes it conduct electric current. Determining the moisture content allows the control of the production cost and the quality of the timber, and also facilitates the use of preservative treatments and painting. The method for the determination of the moisture content using the kiln is the most exact method, and therefore it is used as standard to calibrate other techniques. On the other hand, the verification of the moisture content by means of the kiln takes toe much time and damages part of the component to be analyzed. The aim of this work is to propose a methodology to gauge electric moisture meters using species of tropical and forestation hardwood and softwood. The experiments made it possible to verify that, even having less accuracy in determining the moisture content, the method based on moisture electric meters allows, with some adjustments, a reliable data acquisition for the control of moisture content of sawed lumber. For this matter, equations were developed by means of linear regression analysis allowing the necessary corrections of the readings carried out with the electric measurer of the resistance type.

A madeira quando seca é um excelente isolante elétrico, porém quando a umidade da madeira aumenta, essa característica diminui fazendo com que esta passe a conduzir a corrente elétrica. A determinação do teor de umidade permite um controle do custo de produção e qualidade da madeira, além de facilitar a utilização de tratamentos preservativos e pintura. O método de determinação do teor de umidade com o uso de estufa é o método mais exato, e por esta razão é utilizado como padrão para calibrar outras técnicas. Por outro lado, a verificação do teor de umidade por meio da estufa é muito demorado e danifica parte do componente a ser analisado. O objetivo deste trabalho é propor uma metodologia para calibrar medidores elétricos de umidade, utilizando espécies de dicotiledôneas nativas e coníferas de florestamento. Na experimentação realizada foi possível constatar que apesar da menor precisão na determinação de teores de umidade, o método que utiliza medidores de umidade do tipo resistência, permite com algumas correções, a obtenção de valores confiáveis para o controle de umidade de peças de madeira serrada. Para isso foram desenvolvidas expressões obtidas por meio de análise de regressão linear que possibilitam fazer as correções necessárias nas leituras realizadas com o medidor elétrico do tipo resistência. / Wood when dry is an excellent electric insulating material. However when the moisture content of wood increases, that feature decreases, which makes it conduct electric current. Determining the moisture content allows the control of the production cost and the quality of the timber, and also facilitates the use of preservative treatments and painting. The method for the determination of the moisture content using the kiln is the most exact method, and therefore it is used as standard to calibrate other techniques. On the other hand, the verification of the moisture content by means of the kiln takes toe much time and damages part of the component to be analyzed. The aim of this work is to propose a methodology to gauge electric moisture meters using species of tropical and forestation hardwood and softwood. The experiments made it possible to verify that, even having less accuracy in determining the moisture content, the method based on moisture electric meters allows, with some adjustments, a reliable data acquisition for the control of moisture content of sawed lumber. For this matter, equations were developed by means of linear regression analysis allowing the necessary corrections of the readings carried out with the electric measurer of the resistance type.

Woody biomass transportation costs and market values/costs are strongly correlated with the woody biomass moisture content. Properly managing moisture content can potentially lead to economic and environmental advantages in biomass energy markets. Good management requires accurate moisture content measurements. Therefore, availability of accurate, precise, reliable, and efficient tools to assess woody biomass moisture content is essential. In this study, six different tools (Fibre-Gen HM200, IML Hammer, Humimeter BLW, Timbermaster, Humimeter HM1 and Wile Bio Meter) were evaluated. The six tools employed three different measurement technologies; acoustic, conductance, and capacitance. Woody biomass samples were collected over one season (summer 2011) at three different locations in western Oregon (Corvallis, Dallas, and Clatskanie) for three softwood species and three hardwood species: Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), Ponderosa pine (Pinus ponderosa L.), western hemlock (Tsuga heterophylla (Raf.) Sarg.), hybrid poplar (Populus spp.), Madrone (Arbutus spp.), and Garryana Oak (Quercus garryana Dougl. ex Hook). Twenty 3-meter long log (20 to 400mm diameter) specimens were collected per species; 18 specimens were divided into two different treatments (open vs. covered), and the two remaining specimens were chipped. In addition, approximately 100 kilograms per species of hogfuel (limbs and tops) were collected and chipped. Moisture content measurements of logs, chips, and hogfuel were made regularly over a four month period. These data was used to develop multiple linear regression models for assessing the moisture content of the six species using the six tools. The major factors considered in the regression models were species (6), treatment (2), and tools (6). The data were also used to estimate the sample size needed for each tool. The best tool from each technology type was identified. The results generated from this study show that (1) none of the tools are accurate without calibration for different species, (2) the best model/tool combination could only explain about 80% of the variability in measurements, (3) further product development is required in some cases to ensure that the tools are robust for industrial application, and (4) there is a wide range in efficiency of the tools (i.e., 50 minute tool efficiency range). The Fibre-Gen HM200 and Wile Bio Meter were the most accurate, precise and efficient tools tested. The cost of transporting woody biomass from the forest to woody biomass plants is "optimized" when the moisture content drops to approximately 30% (wet basis). Validation of the models developed for three of the tools tested (Fibre-Gen HM200, Humimeter BLW and the Wile Bio Meter) indicates that the tools are accurate below 35% MC (wet basis). This suggests they could be used for making threshold transportation decisions, i.e., determining when to haul. / Graduation date: 2013