Dissertations / Theses on the topic 'Timber drying'

This thesis is a study of the kiln drying of radiata pine with a primary focus on the change in wood colour that occurs during this process. The energy efficiency of the drying process has also been examined using computer modelling. The aim of this work was to develop guidelines for commercial wood dryers who wish to produce high quality appearance grade timber in a competitive commercial environment. The colour change in radiata pine wood during kiln drying is mainly caused by sap compounds accumulating at the wood surface and reacting to form coloured compounds. The initial research involved drying experiments designed to determine the relationship between this colour change and the kiln schedule and also measure the accumulation of colour forming compounds. The kinetics of the colour change reaction were also measured using two methods, one in-vitro and the other using small samples of wood. From these experiments a colour change equation was developed that predicts the rate of colour formation based on the drying conditions and this was incorporated into a kiln stack model along with an energy efficiency model. The combined model was used to simulate the drying process to find schedules optimised for energy use and wood quality. The model was also used to simulate the energy efficiency of different humidity control configurations for wood drying kilns. A kiln micro-sensor system was also developed for use in kiln diagnostics and control with the particular aim of identifying areas in wood drying kilns with adverse drying conditions. The recommendation to kiln operators wishing to reduce colour change is to not exceed 70? and to use lower relative humidity schedules with a wet bulb depression of 15-20?. Operating at lower humidity can increase the energy used by the kiln so it is also recommended that kiln designers incorporate heat recovery into the humidity control mechanisms of the kiln.

This research examines the drying of hardwood timber with particular reference to seasoning blackbutt (Eucalyptus pilularis) in a solar kiln. The aims of this research were to develop an optimised drying schedule for drying blackbutt and to develop and validate a mathematical model for a solar kiln. In the first stage of this study, the cross-grain physical and mechanical properties were determined for blackbutt timber so that an optimised schedule (based on drying within a limiting strain envelope) can be developed using model predictive control techniques for drying 43 mm thick (green) blackbutt timber boards in solar kilns. This optimised schedule has been developed and tested in the laboratory. The drying time was 10% shorter for this schedule than the original schedule, compared with an expected reduction in drying time of 14% (relative to the original schedule). Overall the quality was slightly better and the drying time was shorter for the optimised schedule compared with the original schedule. A complete solar kiln model has been developed and validated based on comparisons between the predicted and the measured internal air temperatures, relative humidities and timber moisture contents. The maximum difference between the actual and predicted moisture contents was 0.05 kg kg-1. The agreement between the predicted and measured temperatures of the internal air is reasonable, and both the predictions and measurements have a similar cyclical pattern. The generally good agreement between the model prediction of the final moisture content and its measurement may be due to the careful measurement of the boundary conditions such as the solar energy input. The key uncertainties were identified as the heat exchanger output, the measurement of the initial moisture content, the amount of accumulation of condensate on the floor, and the estimation of sky temperature. The significant uncertainty (18%) in the estimation of the initial moisture content is a key reason for the mismatch between the model prediction and the measurements. In terms of operating variables, the energy release rate from the heat exchanger had the greatest effect on the simulated performance, followed by the water spray and venting rates. The simulation suggested that a material with a lower transmissivity to thermal radiation may effectively lower radiation losses, improving the kiln performance, so such materials for glazing is a high priority.

This research examines the drying of hardwood timber with particular reference to seasoning blackbutt (Eucalyptus pilularis) in a solar kiln. The aims of this research were to develop an optimised drying schedule for drying blackbutt and to develop and validate a mathematical model for a solar kiln. In the first stage of this study, the cross-grain physical and mechanical properties were determined for blackbutt timber so that an optimised schedule (based on drying within a limiting strain envelope) can be developed using model predictive control techniques for drying 43 mm thick (green) blackbutt timber boards in solar kilns. This optimised schedule has been developed and tested in the laboratory. The drying time was 10% shorter for this schedule than the original schedule, compared with an expected reduction in drying time of 14% (relative to the original schedule). Overall the quality was slightly better and the drying time was shorter for the optimised schedule compared with the original schedule. A complete solar kiln model has been developed and validated based on comparisons between the predicted and the measured internal air temperatures, relative humidities and timber moisture contents. The maximum difference between the actual and predicted moisture contents was 0.05 kg kg-1. The agreement between the predicted and measured temperatures of the internal air is reasonable, and both the predictions and measurements have a similar cyclical pattern. The generally good agreement between the model prediction of the final moisture content and its measurement may be due to the careful measurement of the boundary conditions such as the solar energy input. The key uncertainties were identified as the heat exchanger output, the measurement of the initial moisture content, the amount of accumulation of condensate on the floor, and the estimation of sky temperature. The significant uncertainty (18%) in the estimation of the initial moisture content is a key reason for the mismatch between the model prediction and the measurements. In terms of operating variables, the energy release rate from the heat exchanger had the greatest effect on the simulated performance, followed by the water spray and venting rates. The simulation suggested that a material with a lower transmissivity to thermal radiation may effectively lower radiation losses, improving the kiln performance, so such materials for glazing is a high priority.

This research examines the drying of hardwood timber with particular reference to seasoning blackbutt (Eucalyptus pilularis) in a solar kiln. The aims of this research were to develop an optimised drying schedule for drying blackbutt and to develop and validate a mathematical model for a solar kiln. In the first stage of this study, the cross-grain physical and mechanical properties were determined for blackbutt timber so that an optimised schedule (based on drying within a limiting strain envelope) can be developed using model predictive control techniques for drying 43 mm thick (green) blackbutt timber boards in solar kilns. This optimised schedule has been developed and tested in the laboratory. The drying time was 10% shorter for this schedule than the original schedule, compared with an expected reduction in drying time of 14% (relative to the original schedule). Overall the quality was slightly better and the drying time was shorter for the optimised schedule compared with the original schedule. A complete solar kiln model has been developed and validated based on comparisons between the predicted and the measured internal air temperatures, relative humidities and timber moisture contents. The maximum difference between the actual and predicted moisture contents was 0.05 kg/kg. The agreement between the predicted and measured temperatures of the internal air is reasonable, and both the predictions and measurements have a similar cyclical pattern. The generally good agreement between the model prediction of the final moisture content and its measurement may be due to the careful measurement of the boundary conditions such as the solar energy input. The key uncertainties were identified as the heat exchanger output, the measurement of the initial moisture content, the amount of accumulation of condensate on the floor, and the estimation of sky temperature. The significant uncertainty (18%) in the estimation of the initial moisture content is a key reason for the mismatch between the model prediction and the measurements. In terms of operating variables, the energy release rate from the heat exchanger had the greatest effect on the simulated performance, followed by the water spray and venting rates. The simulation suggested that a material with a lower transmissivity to thermal radiation may effectively lower radiation losses, improving the kiln performance, so such materials for glazing is a high priority.

This research examines the drying of hardwood timber with particular reference to seasoning blackbutt (Eucalyptus pilularis) in a solar kiln. The aims of this research were to develop an optimised drying schedule for drying blackbutt and to develop and validate a mathematical model for a solar kiln. In the first stage of this study, the cross-grain physical and mechanical properties were determined for blackbutt timber so that an optimised schedule (based on drying within a limiting strain envelope) can be developed using model predictive control techniques for drying 43 mm thick (green) blackbutt timber boards in solar kilns. This optimised schedule has been developed and tested in the laboratory. The drying time was 10% shorter for this schedule than the original schedule, compared with an expected reduction in drying time of 14% (relative to the original schedule). Overall the quality was slightly better and the drying time was shorter for the optimised schedule compared with the original schedule. A complete solar kiln model has been developed and validated based on comparisons between the predicted and the measured internal air temperatures, relative humidities and timber moisture contents. The maximum difference between the actual and predicted moisture contents was 0.05 kg/kg. The agreement between the predicted and measured temperatures of the internal air is reasonable, and both the predictions and measurements have a similar cyclical pattern. The generally good agreement between the model prediction of the final moisture content and its measurement may be due to the careful measurement of the boundary conditions such as the solar energy input. The key uncertainties were identified as the heat exchanger output, the measurement of the initial moisture content, the amount of accumulation of condensate on the floor, and the estimation of sky temperature. The significant uncertainty (18%) in the estimation of the initial moisture content is a key reason for the mismatch between the model prediction and the measurements. In terms of operating variables, the energy release rate from the heat exchanger had the greatest effect on the simulated performance, followed by the water spray and venting rates. The simulation suggested that a material with a lower transmissivity to thermal radiation may effectively lower radiation losses, improving the kiln performance, so such materials for glazing is a high priority.

The impact of the variability in timber properties has been a challenge for companies involved in drying timber, which have to handle these variations and at the same time meet the requirements stated in the Australian/New Zealand Standard for the assessment of dried timber quality (2001). The definition of quality considered in this study is to both minimize the dispersion of the final moisture contents in dried timber boards, and to reduce cracking/checking. Anecdotal evidence also suggests that the timber properties of plantation timber appear to be more variable compared with the properties of old growth or regrowth timber. Therefore, this thesis focuses on measuring the amount of variability of timber properties by conducting drying experiments using timber boards taken from different locations within a single tree and between trees, for regrowth and plantation blackbutt timber (Eucalyptus pilularis Sm.). The quantified variabilities were then used to develop optimized timber drying schedules that are intended to dry regrowth and plantation blackbutt boards as quickly as possible (highest productivity) without cracking (quality loss) in the presence of large biological variability. Blackbutt (Eucalyptus pilularis Sm.) was the chosen species for this thesis because of its abundance in New South Wales. It is considered to be one of the most important eucalypts for planting in NSW. It has superior growth and high survival rates compared with other eucalyptus species, and the timber is marketable. Lastly, conventional kiln drying was considered in this thesis compared with other drying methods such as air drying and solar kilns due to (arguably) better control of the drying conditions and faster throughput in conventional drying. The higher costs of conventional kiln drying are compensated, relative to open—air drying, by the reduction in stock level and faster turnaround of green to dried timber. Firstly, an overview of previous work on the development and evaluation of different drying schedules was given. Previous work either developed optimized drying schedules to minimize the dispersion of the final moisture contents, or reduced cracking/checking. No schedule has been developed to satisfy both aspects of quality. In addition, only one report has taken into consideration biological variability in the development of an optimized drying schedule, but this approach has not been tested experimentally. In addition, the information on the variability of biological parameters was very limited, was assumed to be normally distributed, and the parameters were assumed to be uncorrelated with one another. There is little information about the variability in timber properties with respect to drying, including how strongly they are correlated. This thesis has particularly addressed this aspect of the problem. Drying experiments using conventional kiln drying were conducted. The properties of two regrowth blackbutt logs (36 boards) and two plantation blackbutt logs (24 boards), have been measured and analysed for the within—tree variation of timber properties. In a separate set of experiments, two boards were taken from each log, from a total of 12 regrowth logs and 10 plantation logs, to study the between—tree variability of the timber properties of blackbutt timber. The timber properties measured consisted of the basic density, the initial moisture content, the diffusion coefficient, the failure strain, the failure stress, the modulus of elasticity and the shrinkage. The amount of cracking or checking and the dispersion of final moisture contents were assessed. 90% of the regrowth timber and 90% of the plantation timber fell in the Class C quality for surface checking, regrowth timber fell in Class B for end checking, while the end checks in the plantation timber fell in Class C for quality. Regrowth timber therefore appeared here to have slightly better quality than plantation material when dried with the same drying schedule, as here, in agreement with anecdotal suggestions that plantation material is more difficult to dry well. 95% of both the regrowth and the plantation timber fell in Class E quality for internal checking. Overall, along with the assessment that both regrowth and plantation timber was Class C quality for the variation of final moisture contents, these regrowth timber boards and the plantation timber boards fell in the lower quality classes for the criteria of checking and target moisture content for appearance products. Quality Classes A and B are higher quality categories, for appearance—grade products. The dispersion of the final moisture contents was greater with the plantation blackbutt timber (0.24 within; 0.36 between) than with the regrowth blackbutt timber (0.19 within; 0.15 between) for both within—tree and between—trees variability, respectively. In general, the diffusion coefficients for the timber in this thesis ranged between 1.14×10—10 and 6.77×10—10 m2s—1. There was a significant difference between the diffusion coefficients of the plantation and regrowth blackbutt timber for the within—tree test at a 0.05 significance level. The variation in the diffusion coefficients within a single plantation blackbutt log was higher than the variation in the diffusion coefficients within a regrowth blackbutt log. In addition, there was also a significant difference between the diffusion coefficients of regrowth and plantation blackbutt timber at a 0.05 significance level for between—trees variability. The initial moisture contents, the diffusion coefficient, and shrinkage decreased from pith to bark and the basic density and the modulus of elasticity (MOE) increased in the same direction, within a tree, for both regrowth and plantation blackbutt. The results of the analysis of variance (ANOVA) showed that radial and circumferential effects were significant sources of the within—tree variations for the diffusion coefficient, the initial moisture content, the basic density, the failure strain, the failure stress, the modulus of elasticity and shrinkage. A similar result was found for the ANOVA between trees. The ANOVA results also indicated that the smaller—sized samples used for the analysis (i.e. sub—samples of eight boards for the within—tree test of regrowth blackbutt, sub—samples of four boards for the between—trees test of regrowth blackbutt, sub—samples of six boards for the within—tree test of plantation blackbutt, and sub—samples of six boards for the between—trees test of plantation timber) were sufficient to measure the key effects adequately for the variabilities of the physical, transport, and mechanical properties, provided that all combinations of sub—samples were considered. There was no significant difference between the ANOVA results for these smaller sized samples (less than 1% change), considering all combinations, and the ANOVA results for the ‘full’ board cases. Though the sample sizes were unusually small to represent population statistics by most standards, all combinations of the sub-sets were assessed and an averaged picture of the situation with smaller sample sizes was given. Moreover, MOEs (both green and kiln—dried states) of plantation blackbutt were lower compared with the MOE of regrowth blackbutt. It is possible that the MOE was correlated with the basic density, and the basic density of regrowth blackbutt was higher than the basic density of plantation blackbutt. The shrinkage in the tangential direction was approximately twice the amount of radial shrinkage. The ranges of the measured radial shrinkage values were 0.024 – 0.094 mm mm-1 for regrowth blackbutt and 0.037 – 0.125 mm mm-1 for plantation blackbutt. The higher shrinkage values for plantation blackbutt timber show that plantation material is less stable dimensionally, and this situation is possibly due to the high juvenile wood content and low basic density. These differential (tangential:radial) shrinkage values ranged from 1.12 – 2.93 for regrowth blackbutt and 1.09 – 2.92 for plantation blackbutt. Tests were conducted to determine the degree of statistical normality for the distribution of each property (physical, transport, and mechanical). The results of the normality tests showed that most timber properties for regrowth and plantation blackbutt timber were distributed normally on a linear scale based on the W test, both within and between—trees. On the other hand, some timber properties showed a better fit with the three—parameter lognormal distribution, such as the diffusion coefficient and the green failure strain for within—tree variability of regrowth timber. The means and standard deviations of these distributions were further analysed by applying significance tests at a 0.05 level. For regrowth blackbutt, the data for the initial moisture content, the basic density, the diffusion coefficient, and shrinkage showed no significant differences, comparing the cases within and between—trees. The mechanical behaviour, however, was significantly different between each group and suggested that the two regrowth trees used for the within—tree test were stiffer than the 12 trees used for the between—trees test. It was possible that the mechanical properties were dependent on the geographic location where the tree was felled, and the heartwood content of each log. On the other hand, since all the plantation logs used for the within and between—trees tests were taken from one location, the mechanical properties were not significantly different within the plantation sample. The silviculture and the age of all the plantation trees were the same, which might have contributed to the small variation of the timber properties between the within—tree and between—trees cases for plantation material. Lastly, a significance test was conducted to compare the properties of regrowth and plantation blackbutt timber. Most timber properties (except for the initial moisture content) were significantly different between regrowth and plantation blackbutt. Plantation blackbutt timber had a lower basic density, higher diffusion coefficient and shrinkage, and the modulus of elasticity (both in its green and dried states) was lower compared with regrowth blackbutt timber. In addition to geographic location, heartwood/juvenile content, maturity (age), and differences in microfibril angle may have affected these timber properties in plantation blackbutt timber. For all the experiments, the possibility that there is a correlation between high initial moisture contents, higher diffusion coefficients, low basic densities, and low green modulus of elasticity’s (MOE) was assessed using principal components analysis (PCA). A principal components analysis was performed on the four parameters: the basic density, the initial moisture content, the diffusion coefficient, and the green MOE. The results of the PCA showed that the principal component for the within—tree and between—trees test accounted for 93% and 94% (for regrowth), and 92% and 90% (for plantation), respectively, of the total amount of variation within these parameters, giving some support for the mentioned correlation between the parameters. The strong correlation between the diffusion coefficient and the basic density, D; the diffusion coefficient and the initial moisture content, Xi; and the diffusion coefficient, D, and the modulus of elasticity, EG were represented by empirical equations. The F significance test was conducted to determine if the equations from the within—tree and between—trees tests, and the regrowth blackbutt and plantation blackbutt tests, were significantly different. The difference between the equations for the within—tree and between—trees variability of plantation blackbutt timber (Factual= 1.35  Fexpected= 2.13) was the only result that showed no significant difference. A possible reason for this finding is that the boards from the within—tree and between—tree variability tests, hence the trees, were all felled from one location. On the other hand, the other tests compared boards that were taken from trees felled from different locations, including the regrowth blackbutt within trees, compared with between trees. The results of the significance tests imply that boards taken from one location, whether they are within—tree and between—tree samples, have probably come from the same overall population. Hence using any of the correlations (within—tree or between—trees for plantation blackbutt) would be suitable to estimate the diffusion coefficient of other plantation blackbutt samples at the same location. Overall, these empirical equations can be used to estimate important drying properties of other regrowth and plantation blackbutt samples, such as the diffusion coefficient, using easily measured properties, like the initial moisture content or the basic density, as long as the boards are taken from the same age group (i.e. regrowth or plantation) and the same location. Thereafter, the blackbutt timber boards may be segregated based on the range of diffusion coefficients as estimated from the densities or the initial moisture contents. Hence a suitable drying schedule should be chosen for each segregated group. Collapse was not significant for blackbutt samples studied in this thesis, and possibly this timber species in general, but it may be significant for other eucalyptus species such as collapse—prone Eucalyptus regnans F. Muell (mountain ash) This potential limitation means that care is needed in applying the relationships found in this thesis to collapse—prone species. The same drying model was used to assess the effects of different drying schedules (i.e. increasing and decreasing the dry—bulb and wet—bulb temperatures of the original drying schedule by 5oC and 10oC) and of the potential correlations between the diffusion coefficient, the green MOE, the shrinkage coefficient (calculated from the tangential shrinkage), and the initial moisture content on the variability of final moisture contents, when the average moisture content within a stack of timber reached 15%. In addition, the maximum strain attained by the timber boards was also predicted. The results show that for regrowth blackbutt timber and accounting for within—tree variability, there was no relationship between the length of the drying schedule and the dispersion of final moisture contents. As the temperatures increased, the dispersion of the final moisture contents showed no consistent trend. The absence of a clear trend may be due to the different locations where the logs used for the within—tree test of regrowth variability were taken. On the other hand, the between—tree variability sensitivity tests for both regrowth and plantation blackbutt timber and the within—tree variability sensitivity test for plantation blackbutt timber show a relationship between the length of the drying schedule and the dispersion of final moisture contents. The dispersion of the final moisture contents decreased as temperatures increased. Generally, the ‘+10oC’ drying schedule gave the shortest time for the stack of timber to reach the target average moisture content, and its conditions produced the smallest dispersion of final moisture contents. It was also observed, however, for all sensitivity tests, that as the temperature of the drying schedule increased, the average predicted values decreased for the maximum strains reached. This is a very unusual result, because normally the strains and stresses would be expected to increase with increasing temperature. A possible reason for this is that within a piece of timber, as the temperatures increase, the diffusion coefficient will increase because the internal average temperature increases, so the internal resistance to mass transfer decreases, which leads to the moisture content gradient decreasing, even though the drying rate may slightly increase. This decreases both the drying time and the maximum strain reached as the temperature increases. There are limitations, however, associated when using high temperatures in kiln drying such as collapse and timber discolouration. The optimization technique created by Pordage (2006) was improved by using a large number of measurements to quantify the variability in the properties of blackbutt timber. The first simulation accounted for the between—tree variability of the biological parameters in regrowth blackbutt, and the second simulation accounted for both the within and between—tree variability of the timber properties in plantation blackbutt. Since location was observed as a main source of variability, the timber properties used for each simulation were taken from the logs that were felled from the same location. The mean and the standard deviations of the initial moisture content, the reference diffusion coefficient, and the shrinkage coefficient of regrowth and plantation blackbutt timber boards measured in the actual drying experiments, along with the covariance between these properties represented by a covariance matrix, were used for each simulation. The total drying time of the optimized drying schedule of plantation blackbutt timber was longer (an additional 168 hours, i.e. 472 hours) compared with the total drying time of the optimized drying schedule of regrowth blackbutt timber (304 hours). Due to the greater variability present in plantation blackbutt, slower drying is required. Moreover, the total drying times from the ‘regrowth blackbutt’ optimization and the ‘plantation blackbutt’ optimization (which both accounted for variability) were shorter compared with the total drying time of the original drying schedule for 28 mm—thick mixed—sawn blackbutt boards, i.e. 504 hours. On the other hand, the total drying times of the optimized drying schedules of regrowth and plantation blackbutt timber were greater than the total drying time (152 hours) predicted by Pordage’s (2006) optimized drying schedule accounting for the variability of Eucalyptus paniculata (grey ironbark). He had limited information on the variability of the parameters of grey ironbark and thus used an estimate from another eucalyptus species, Eucalyptus obliqua (messmate), whereas in this thesis, the variabilities for regrowth and plantation blackbutt used for the optimization technique were measured and part of the scope for this study. Overall, this is a typical application of the data obtained in this thesis to the optimization of drying schedules.

Doctor of Philosophy
The impact of the variability in timber properties has been a challenge for companies involved in drying timber, which have to handle these variations and at the same time meet the requirements stated in the Australian/New Zealand Standard for the assessment of dried timber quality (2001). The definition of quality considered in this study is to both minimize the dispersion of the final moisture contents in dried timber boards, and to reduce cracking/checking. Anecdotal evidence also suggests that the timber properties of plantation timber appear to be more variable compared with the properties of old growth or regrowth timber. Therefore, this thesis focuses on measuring the amount of variability of timber properties by conducting drying experiments using timber boards taken from different locations within a single tree and between trees, for regrowth and plantation blackbutt timber (Eucalyptus pilularis Sm.). The quantified variabilities were then used to develop optimized timber drying schedules that are intended to dry regrowth and plantation blackbutt boards as quickly as possible (highest productivity) without cracking (quality loss) in the presence of large biological variability. Blackbutt (Eucalyptus pilularis Sm.) was the chosen species for this thesis because of its abundance in New South Wales. It is considered to be one of the most important eucalypts for planting in NSW. It has superior growth and high survival rates compared with other eucalyptus species, and the timber is marketable. Lastly, conventional kiln drying was considered in this thesis compared with other drying methods such as air drying and solar kilns due to (arguably) better control of the drying conditions and faster throughput in conventional drying. The higher costs of conventional kiln drying are compensated, relative to open—air drying, by the reduction in stock level and faster turnaround of green to dried timber. Firstly, an overview of previous work on the development and evaluation of different drying schedules was given. Previous work either developed optimized drying schedules to minimize the dispersion of the final moisture contents, or reduced cracking/checking. No schedule has been developed to satisfy both aspects of quality. In addition, only one report has taken into consideration biological variability in the development of an optimized drying schedule, but this approach has not been tested experimentally. In addition, the information on the variability of biological parameters was very limited, was assumed to be normally distributed, and the parameters were assumed to be uncorrelated with one another. There is little information about the variability in timber properties with respect to drying, including how strongly they are correlated. This thesis has particularly addressed this aspect of the problem. Drying experiments using conventional kiln drying were conducted. The properties of two regrowth blackbutt logs (36 boards) and two plantation blackbutt logs (24 boards), have been measured and analysed for the within—tree variation of timber properties. In a separate set of experiments, two boards were taken from each log, from a total of 12 regrowth logs and 10 plantation logs, to study the between—tree variability of the timber properties of blackbutt timber. The timber properties measured consisted of the basic density, the initial moisture content, the diffusion coefficient, the failure strain, the failure stress, the modulus of elasticity and the shrinkage. The amount of cracking or checking and the dispersion of final moisture contents were assessed. 90% of the regrowth timber and 90% of the plantation timber fell in the Class C quality for surface checking, regrowth timber fell in Class B for end checking, while the end checks in the plantation timber fell in Class C for quality. Regrowth timber therefore appeared here to have slightly better quality than plantation material when dried with the same drying schedule, as here, in agreement with anecdotal suggestions that plantation material is more difficult to dry well. 95% of both the regrowth and the plantation timber fell in Class E quality for internal checking. Overall, along with the assessment that both regrowth and plantation timber was Class C quality for the variation of final moisture contents, these regrowth timber boards and the plantation timber boards fell in the lower quality classes for the criteria of checking and target moisture content for appearance products. Quality Classes A and B are higher quality categories, for appearance—grade products. The dispersion of the final moisture contents was greater with the plantation blackbutt timber (0.24 within; 0.36 between) than with the regrowth blackbutt timber (0.19 within; 0.15 between) for both within—tree and between—trees variability, respectively. In general, the diffusion coefficients for the timber in this thesis ranged between 1.14×10—10 and 6.77×10—10 m2s—1. There was a significant difference between the diffusion coefficients of the plantation and regrowth blackbutt timber for the within—tree test at a 0.05 significance level. The variation in the diffusion coefficients within a single plantation blackbutt log was higher than the variation in the diffusion coefficients within a regrowth blackbutt log. In addition, there was also a significant difference between the diffusion coefficients of regrowth and plantation blackbutt timber at a 0.05 significance level for between—trees variability. The initial moisture contents, the diffusion coefficient, and shrinkage decreased from pith to bark and the basic density and the modulus of elasticity (MOE) increased in the same direction, within a tree, for both regrowth and plantation blackbutt. The results of the analysis of variance (ANOVA) showed that radial and circumferential effects were significant sources of the within—tree variations for the diffusion coefficient, the initial moisture content, the basic density, the failure strain, the failure stress, the modulus of elasticity and shrinkage. A similar result was found for the ANOVA between trees. The ANOVA results also indicated that the smaller—sized samples used for the analysis (i.e. sub—samples of eight boards for the within—tree test of regrowth blackbutt, sub—samples of four boards for the between—trees test of regrowth blackbutt, sub—samples of six boards for the within—tree test of plantation blackbutt, and sub—samples of six boards for the between—trees test of plantation timber) were sufficient to measure the key effects adequately for the variabilities of the physical, transport, and mechanical properties, provided that all combinations of sub—samples were considered. There was no significant difference between the ANOVA results for these smaller sized samples (less than 1% change), considering all combinations, and the ANOVA results for the ‘full’ board cases. Though the sample sizes were unusually small to represent population statistics by most standards, all combinations of the sub-sets were assessed and an averaged picture of the situation with smaller sample sizes was given. Moreover, MOEs (both green and kiln—dried states) of plantation blackbutt were lower compared with the MOE of regrowth blackbutt. It is possible that the MOE was correlated with the basic density, and the basic density of regrowth blackbutt was higher than the basic density of plantation blackbutt. The shrinkage in the tangential direction was approximately twice the amount of radial shrinkage. The ranges of the measured radial shrinkage values were 0.024 – 0.094 mm mm-1 for regrowth blackbutt and 0.037 – 0.125 mm mm-1 for plantation blackbutt. The higher shrinkage values for plantation blackbutt timber show that plantation material is less stable dimensionally, and this situation is possibly due to the high juvenile wood content and low basic density. These differential (tangential:radial) shrinkage values ranged from 1.12 – 2.93 for regrowth blackbutt and 1.09 – 2.92 for plantation blackbutt. Tests were conducted to determine the degree of statistical normality for the distribution of each property (physical, transport, and mechanical). The results of the normality tests showed that most timber properties for regrowth and plantation blackbutt timber were distributed normally on a linear scale based on the W test, both within and between—trees. On the other hand, some timber properties showed a better fit with the three—parameter lognormal distribution, such as the diffusion coefficient and the green failure strain for within—tree variability of regrowth timber. The means and standard deviations of these distributions were further analysed by applying significance tests at a 0.05 level. For regrowth blackbutt, the data for the initial moisture content, the basic density, the diffusion coefficient, and shrinkage showed no significant differences, comparing the cases within and between—trees. The mechanical behaviour, however, was significantly different between each group and suggested that the two regrowth trees used for the within—tree test were stiffer than the 12 trees used for the between—trees test. It was possible that the mechanical properties were dependent on the geographic location where the tree was felled, and the heartwood content of each log. On the other hand, since all the plantation logs used for the within and between—trees tests were taken from one location, the mechanical properties were not significantly different within the plantation sample. The silviculture and the age of all the plantation trees were the same, which might have contributed to the small variation of the timber properties between the within—tree and between—trees cases for plantation material. Lastly, a significance test was conducted to compare the properties of regrowth and plantation blackbutt timber. Most timber properties (except for the initial moisture content) were significantly different between regrowth and plantation blackbutt. Plantation blackbutt timber had a lower basic density, higher diffusion coefficient and shrinkage, and the modulus of elasticity (both in its green and dried states) was lower compared with regrowth blackbutt timber. In addition to geographic location, heartwood/juvenile content, maturity (age), and differences in microfibril angle may have affected these timber properties in plantation blackbutt timber. For all the experiments, the possibility that there is a correlation between high initial moisture contents, higher diffusion coefficients, low basic densities, and low green modulus of elasticity’s (MOE) was assessed using principal components analysis (PCA). A principal components analysis was performed on the four parameters: the basic density, the initial moisture content, the diffusion coefficient, and the green MOE. The results of the PCA showed that the principal component for the within—tree and between—trees test accounted for 93% and 94% (for regrowth), and 92% and 90% (for plantation), respectively, of the total amount of variation within these parameters, giving some support for the mentioned correlation between the parameters. The strong correlation between the diffusion coefficient and the basic density, D; the diffusion coefficient and the initial moisture content, Xi; and the diffusion coefficient, D, and the modulus of elasticity, EG were represented by empirical equations. The F significance test was conducted to determine if the equations from the within—tree and between—trees tests, and the regrowth blackbutt and plantation blackbutt tests, were significantly different. The difference between the equations for the within—tree and between—trees variability of plantation blackbutt timber (Factual= 1.35  Fexpected= 2.13) was the only result that showed no significant difference. A possible reason for this finding is that the boards from the within—tree and between—tree variability tests, hence the trees, were all felled from one location. On the other hand, the other tests compared boards that were taken from trees felled from different locations, including the regrowth blackbutt within trees, compared with between trees. The results of the significance tests imply that boards taken from one location, whether they are within—tree and between—tree samples, have probably come from the same overall population. Hence using any of the correlations (within—tree or between—trees for plantation blackbutt) would be suitable to estimate the diffusion coefficient of other plantation blackbutt samples at the same location. Overall, these empirical equations can be used to estimate important drying properties of other regrowth and plantation blackbutt samples, such as the diffusion coefficient, using easily measured properties, like the initial moisture content or the basic density, as long as the boards are taken from the same age group (i.e. regrowth or plantation) and the same location. Thereafter, the blackbutt timber boards may be segregated based on the range of diffusion coefficients as estimated from the densities or the initial moisture contents. Hence a suitable drying schedule should be chosen for each segregated group. Collapse was not significant for blackbutt samples studied in this thesis, and possibly this timber species in general, but it may be significant for other eucalyptus species such as collapse—prone Eucalyptus regnans F. Muell (mountain ash) This potential limitation means that care is needed in applying the relationships found in this thesis to collapse—prone species. The same drying model was used to assess the effects of different drying schedules (i.e. increasing and decreasing the dry—bulb and wet—bulb temperatures of the original drying schedule by 5oC and 10oC) and of the potential correlations between the diffusion coefficient, the green MOE, the shrinkage coefficient (calculated from the tangential shrinkage), and the initial moisture content on the variability of final moisture contents, when the average moisture content within a stack of timber reached 15%. In addition, the maximum strain attained by the timber boards was also predicted. The results show that for regrowth blackbutt timber and accounting for within—tree variability, there was no relationship between the length of the drying schedule and the dispersion of final moisture contents. As the temperatures increased, the dispersion of the final moisture contents showed no consistent trend. The absence of a clear trend may be due to the different locations where the logs used for the within—tree test of regrowth variability were taken. On the other hand, the between—tree variability sensitivity tests for both regrowth and plantation blackbutt timber and the within—tree variability sensitivity test for plantation blackbutt timber show a relationship between the length of the drying schedule and the dispersion of final moisture contents. The dispersion of the final moisture contents decreased as temperatures increased. Generally, the ‘+10oC’ drying schedule gave the shortest time for the stack of timber to reach the target average moisture content, and its conditions produced the smallest dispersion of final moisture contents. It was also observed, however, for all sensitivity tests, that as the temperature of the drying schedule increased, the average predicted values decreased for the maximum strains reached. This is a very unusual result, because normally the strains and stresses would be expected to increase with increasing temperature. A possible reason for this is that within a piece of timber, as the temperatures increase, the diffusion coefficient will increase because the internal average temperature increases, so the internal resistance to mass transfer decreases, which leads to the moisture content gradient decreasing, even though the drying rate may slightly increase. This decreases both the drying time and the maximum strain reached as the temperature increases. There are limitations, however, associated when using high temperatures in kiln drying such as collapse and timber discolouration. The optimization technique created by Pordage (2006) was improved by using a large number of measurements to quantify the variability in the properties of blackbutt timber. The first simulation accounted for the between—tree variability of the biological parameters in regrowth blackbutt, and the second simulation accounted for both the within and between—tree variability of the timber properties in plantation blackbutt. Since location was observed as a main source of variability, the timber properties used for each simulation were taken from the logs that were felled from the same location. The mean and the standard deviations of the initial moisture content, the reference diffusion coefficient, and the shrinkage coefficient of regrowth and plantation blackbutt timber boards measured in the actual drying experiments, along with the covariance between these properties represented by a covariance matrix, were used for each simulation. The total drying time of the optimized drying schedule of plantation blackbutt timber was longer (an additional 168 hours, i.e. 472 hours) compared with the total drying time of the optimized drying schedule of regrowth blackbutt timber (304 hours). Due to the greater variability present in plantation blackbutt, slower drying is required. Moreover, the total drying times from the ‘regrowth blackbutt’ optimization and the ‘plantation blackbutt’ optimization (which both accounted for variability) were shorter compared with the total drying time of the original drying schedule for 28 mm—thick mixed—sawn blackbutt boards, i.e. 504 hours. On the other hand, the total drying times of the optimized drying schedules of regrowth and plantation blackbutt timber were greater than the total drying time (152 hours) predicted by Pordage’s (2006) optimized drying schedule accounting for the variability of Eucalyptus paniculata (grey ironbark). He had limited information on the variability of the parameters of grey ironbark and thus used an estimate from another eucalyptus species, Eucalyptus obliqua (messmate), whereas in this thesis, the variabilities for regrowth and plantation blackbutt used for the optimization technique were measured and part of the scope for this study. Overall, this is a typical application of the data obtained in this thesis to the optimization of drying schedules.

A series of experiments was conducted with the view of obtaining baseline information on the use of polyethylene glycol (PEG) on Tasmanian Oak for the purpose of improving the quality of the seasoned structural timber product. Tasmanian Oak is the marketing name for a triad of Tasmanian-grown eucalypt species (E. delegatensis, E. obliqua, and E. regnans). Incubation of freshly-milled timber in aqueous PEG solutions prior to seasoning follows on from investigations in northern hemispheric timber species such as hoop pine and spruce in the middle of the 20th Century. PEG penetrates freshly sawn Tasmanian Oak in a manner which is considerate of incubation time, temperature, PEG molecular weight/size and timber density. Histological examination indicated that PEG penetrated completely throughout the structure of the wood substance in three orientations (transverse, radial and tangential). During air-drying of PEG soaked timber, further migration of PEG into Tasmanian Oak is negligible. The rate of moisture content loss in Tasmanian Oak was shown to be retarded by PEG pre-treatment although the ability to prevent moisture loss was not concomitant with dimensional stability. An investigation to explain the change in rate of moisture loss examined effects on the thermodynamic property, water activity. Results indicated that a change in solution water activity could partly expain changes in the rate of moisture content loss, but more research is required to better divine this relationship. Shrinkage in Tasmanian Oak was reduced after treatment with aqueous PEG 400 solutions at or above 30% (v/v), with a greater percentage reduction in tangential shrinkage compared to reduction in radial shrinkage. This is significant as backsawn (a.k.a. flatsawn) timber, with its broader tangential face, was in particular focus. The reduction in shrinkage was consistent with PEG concentration in the incubating medium. A decrease in the formation of drying defect, such as surface and internal checking accompanied the improvement in keeping sawn dimensions. Backsawn Tasmanian Oak obtained from young trees (less than 20 years) from plantation resource presents a challenging profile for commercial timber drying and will become more prevalent as the logging of old-growth forests is phased out. Timber seasoners may be faced with options of longer drying times or lower yields due to drying defect unless a method can be developed to provide added protection to the sawn timber product during drying. At this stage, pre-treatment of Tasmanian Oak with PEG shows the hallmarks of providing a solution to this emerging dilemma.

Le séchage du bois d’œuvre étant une opération très énergivore, l’utilisation des énergies intermittentes est l’une des solutions envisageables afin de réduire la consommation énergétique au cours de cette opération. Néanmoins, ne pouvant utiliser les conduites de séchage actuellement préconisées à cause de la fluctuation de l’apport énergétique, l’utilisation de ce type d’énergies soulève plusieurs questions notamment sur l’impact de la fluctuation de la température sur la qualité du séchage et les conduites de séchage à adopter afin de réaliser un compromis entre durée, qualité et coût. Ce travail de thèse vise à apporter des réponses à ces questions par une approche équilibrée entre expérimentation et modélisation. L’étude expérimentale a montré que l’intermittence des conditions de séchage ne ralentit pas la cinétique de séchage par rapport à un séchage où la teneur en eau d’équilibre et la température moyenne sont identiques et maintenues constantes. De plus, une meilleure qualité semble pouvoir être obtenue par l’intermittence des conditions de séchage. Ces résultats ont été confrontés aux simulations d’un modèle numérique double échelle utilisant le code TransPore à l’échelle de la planche. Son potentiel prédictif a été vérifié et il a ensuite été utilisé pour mieux comprendre l’effet des conditions intermittentes sur la qualité et la durée du séchage à l'échelle d'une planche seule et à l'échelle d'une pile de planches. Il a permis de montrer que l’oscillation des conditions de séchage active la mécanosorption et relaxe une partie des contraintes de séchage. Les gains apportés sont limités à l’échelle d’une planche seule, mais ils peuvent être plus importants à l’échelle d’une pile de planches. Le séchage intermittent s’avère plus intéressant pour un séchage lent tel qu’un séchage à basse température, des essences plus difficiles à sécher ou encore pour des planches de fortes épaisseurs. Le code a été ensuite utilisé pour comparer différentes stratégies de séchage à basse température. Un compromis a pu être obtenu entre durée et qualité en réalisant un pré-séchage avec une énergie intermittente à basse température suivi d’un séchage convectif à plus haute température cependant la durée reste longue pour les autres configurations imposant une étude de faisabilité économique. Un module économique a été développé en Fortran et greffé dans le code numérique multi-échelle Planche-Pile-Séchoir afin d’intégrer le critère coût dans l’étude des différentes stratégies
Timber drying is an energy intensive process, the use of intermittent energy sources is one of the possible solutions to reduce energy consumption during this operation. However, the use of the conventional drying schedules is not suitable because of the fluctuation of energy intake, the use of this type of energy raises several issues as the impact of the fluctuation of temperature on drying quality, or the drying strategies to use in order to achieve a compromise between time, quality and cost. This thesis aims to provide answers to these questions through a balanced approach between experimentation and modeling. The experimental study has shown that intermittent drying conditions do not slow the drying rate compared to drying wherein the equilibrium moisture content and the average dry bulb temperature are identical and maintained constant during drying. Moreover, better quality seems to be obtained by the intermittent drying conditions. These results were compared to simulations of a dual scale numerical model using the code TransPore at the board scale. Its predictive potential was checked and it was later used to better understand the effect of intermittent conditions on the drying quality and time at the board and stack scales. It showed that the oscillation of drying conditions activates the mechanosorption and relaxes some of drying stresses. The benefits on the drying quality are limited when a single board is dried, but benefits may be more important when a boards stack is dried. The intermittent drying seems to be more interesting in the case of slow drying such as drying at low temperature, more difficult species to dry or for thick timbers. The code was then used to compare different drying strategies at low temperature level with oscillate conditions. A compromise was reached between duration and quality by achieving a pre-drying using a low temperature intermittent drying followed by convective drying at higher temperatures, however, the drying time is still long for other configurations imposing an economic feasibility study. An economic module was developed in Fortran and grafted in the multiscale computational model Board-Stack-Kiln to integrate the cost criterion in the study of the different strategies

This study aimed to investigate the changes of internal moisture content distributions of high-value hem-fir timbers after kiln drying while exposed to two different local outdoors seasonal conditions for a period of time of few weeks. Hem-fir is the most abundant species in coastal British Columbia, Canada, and high-quality thick hem-fir timbers used as construction material are one of the most important, and profitable products due to international market demand especially in Japan. Presently more-and-more of those houses are pre-fabricated and dimensional stability is paramount. Internal moisture profiles after kiln drying and their behaviour as a function of weather exposure in storage can result in dimensionally unstable products and consequently compromise quality. Conventional kiln drying of thick timbers is relatively difficult and requires long drying time to reduce final moisture content variation. Fast drying will result in steep moisture content gradients which may result in undesirable dimensional changes when products are used in normal service conditions. Thus, it is important to understand moisture behavior after drying and how that is affected by the environment. In this study, 90 x 90 mm in cross-section hem-fir timbers were dried to three different target moisture contents. Thereafter, stickered packages were stored under two diverse seasonal coastal environments thus emulating outdoor timber storage in a local sawmill. Moisture contents at 25 mm and 45 mm depths were continuously monitored for a period of three weeks. The results showed that moisture movement was observed between at 25 mm and at 45 mm depths regardless seasonal conditions while no significant net moisture content reduction took place during the cold-wet season after kiln drying. Also, regardless seasonal condition or target moisture content, moisture movement between at 25 mm and at 45 mm depths slowed down when differential moisture content between them was below 2.5%. In particular, at high target moisture content of 22%, moisture content values both at 25 mm and at 45 mm depths remained constant at moisture content difference value of 2.5% after two weeks regardless seasonal conditions, and no further drying or no further moisture content equalization were observed after that point.

La modélisation numérique des structures bois dans des conditions d’incendie nécessite la connaissance : de la variation des propriétés physiques du bois telles que la conductivité thermique, la chaleur spécifique et la densité en fonction de la température ; de la dégradation thermique du bois au cours des phases de séchage, de pyrolyse et de combustion. En particulier, nous nous sommes intéressés à l’étude du comportement thermomécanique du matériau bois. La loi thermique est décrite par l’équation de la chaleur. Le modèle choisi intègre les trois modes du transfert de chaleur : la conduction, le rayonnement et la convection. La loi mécanique est modélisée dans le cadre de la thermodynamique des processus irréversibles utilisant la notion des variables d’état. Elle tient compte du couplage entre le comportement élastique orthotrope, plastique anisotrope à écrouissage non linéaire isotrope et un endommagement isotrope. L’intégration numérique de la loi mécanique par un schéma implicite itératif combinant la technique du retour radial avec la réduction du nombre des équations est présentée. Le couplage thermomécanique est réalisé, selon l’approche réglementaire de l’Eurocode 5 relatif à la résistance au feu des structures en bois, en appliquant le facteur de réduction Kθ sur la résistance mécanique d’un résineux. Les aspects théoriques et les conditions aux limites associés au modèle thermomécanique sont abordés. L’identification des paramètres du modèle est réalisée sur des données expérimentales obtenues sur des tests réels d’incendie disponibles dans la littérature. À ce titre, plusieurs comparaisons avec différentes applications sont réalisées. Le modèle éléments finis reproduit avec précision la distribution du champ de température dans l’épaisseur des panneaux en bois, la formation du charbon ainsi que l’évolution de la résistance mécanique au cours de l’exposition au feu
Numerical modelling of timber structures in fire conditions requires the knowledge of the variation with temperature of the physical properties of the wood material (the thermal conductivity, the specific heat and the density) in order to take into account the thermal degradation of wood under high temperatures during the drying, pyrolysis and combustion phases, as well as the temperature profiles in the thickness of the surfaces exposed to fire. In particular, this work focusses on the thermomechanical behaviour of timber. The heat transfer analysis is described by the standard equations of heat conduction. It includes the three modes of heat transfer: conduction, radiation and convection. The structural response is modelled within the framework of thermodynamics of irreversible processes using the notion of state variables. It takes into account the coupling between the orthotropic elastic behaviour, the anisotropic plastic behaviour with isotropic nonlinear hardening, and isotropic damage. The numerical integration of the equilibrium equations is carried out with an iterative implicit scheme combining the technique of radial re- turn with the reduction of the number of equations. The thermomechanical coupling is carried out according to the approach recommended by Eurocode 5 for the fire resistance of timber structures by applying the reduction factor Kθ to the strength of a softwood. The theoretical aspects and boundary conditions associated with the thermomechanical model are also discussed. The parameters of the model are identified with experimental data obtained from actual fire tests available in the literature. Several comparative applications are carried out. The finite element model accurately reproduces the distribution of the temperature profile in the thickness of timber planks, the formation of the charred layer, and the evolution of the mechanical resistance during exposure to fire

Uma vez que o café é uma das principais receitas de Timor-Leste e o primeiro produto agrícola a garantir o rendimento a cerca de um quarto da população, julgou-se ser interessante observar e caracterizar a produção do café Arábica de Ermera, e avaliar os efeitos de aplicação de diferentes tecnologias no processo de secagem para melhorar a sua qualidade na Cooperativa Café Timor. Na primeira parte do trabalho, aborda-se directamente o objectivo de identificar e caracterizar as actividades relacionadas com o sistema de produção de café na Cooperativa e na Empresa supramencionadas, incidindo especialmente sobre o processo de secagem do café. Seguidamente, a partir de Abril de 2012, efectuou-se um trabalho experimental composto por duas experiências: Experiência 1. Efeito da cor da lona na qualidade do café arábica de Timor; Experiência 2. Efeito do tempo de fermentação na qualidade do café arábica de Timor; Estes ensaios foram desenvolvidos em Timor-Leste, juntos locais de produção da Cooperativa Café Timor (CCT). Após a realização do trabalho experimental, procedeu-se ao tratamento e análise de dados, apresentação de resultados e sua discussão. Os resultados desta pesquisa indicam que a cor da lona tem uma influência significativa no temperatura e teor de água dos grãos de café ao longo do processo de secagem levando a lona preta a temperaturas mais elevadas e menores teores de água do que as lonas de cor branca ou azul. O tempo de fermentação só teve uma influência significativa na acidez do café, onde se verificou que maiores tempos de fermentação originam uma acidez mais elevada. Deste modo recomenda-se que estes aspectos sejam levados em conta no tratamento pós-colheita dos grãos de café arábica de Timor; **** ABSTRACT: Once the coffee is a major in revenue Timor-Leste and the first crop to ensure income to about a quarter of the population, it was thought to be interesting to observe and characterize the production of Arabica coffee in Ermera District, and evaluate the application effects of different technologies in coffee drying process in order to improve its quality in Cooperative Café Timor (CCT). In the first part of the work, the objective of identifying and characterizing the activities related to the system of coffee production in the Cooperative and Company above mentioned are directly addressed, by focusing on the process of drying coffee. From April 2012, we performed an experimental study that consisted of two experiments: Experiment 1. The effect canvas colour on the quality of Arabica coffee in Timor-Leste; Experiment 2. The effect of fermentation time on the quality of Arabica coffee in Timor-Leste; These experiments were developed in Timor-Leste, together local production of CCT. After completion of the experimental work, data treatment and analysis, presentation of results and discussion was performed. These results indicate that canvas colour has a significant influence on the temperature and water content of coffee beans throughout the drying process, leading black canvas to higher temperatures and lower water contents than the white or blue colour canvas. The fermentation time, so, had a significant influence on the acidity of the coffee, where longer fermentation times originate a higher acidity. Thus, it is recommended that these aspects be taken into account in postharvest treatment of Arabica coffee beans from Timor-Leste.

The active ventilation of grain with the optimum drying regimen was the main issue of the work. The moisture of the harvested grain in Lithuania often exceeds the conditional one. Thus the grain should by dried before the storage. The active ventilation is mostly used in Lithuania to dry the grain, it was the topical point in this work. There was analyzed meteorology of the topical months, were maked the calculating equations, whitch we can prognosticate these meteorological facts: temperature and relative humidity. The maked mathematical model defines metathesis moisture‘s between ambient air flow and grain. Also there were the algorithm of model‘s realisation‘s and the computer programme with Visual basic 6.0 maked. Adequacy of mathematical model‘s was rated with results of experimental researches and calculated results.

This research project is a step forward in predicting the bulk-scale deformations in food-plant materials during drying in a computationally efficient and accurate manner. In the proposed numerical modelling method, a novel force interaction field was introduced to represent the mechanics of a whole plant cell during drying through its centroid. By utilising this novel modelling approach, the distinct deformation profiles of several food-plant materials were revealed along with the impact of drying situations and features in the microstructure. The developed modelling framework has potential applications in the field of food engineering in controlling quality attributes of dried food-plant products.

Orientador : Celso Costa Lopes
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: A banana crocante, para ser consumida na forma de snacks, pode ser obtida através de secagem com ar a altas temperaturas por um curto período de tempo (HTST ¿ High Temperature Short Time) na fase inicial de secagem, seguida da secagem à temperatura média (50-70°C). O objetivo deste trabalho foi avaliar a influência da composição química da banana nanica (Musa acuminata Colla subgrupo Cavendish), proveniente de duas origens e três graus de maturação sobre as características de crocância e cor do produto final, o qual foi obtido através de secagem utilizando a etapa HTST a 150°C. O indicador do ponto final do processo foi aw da banana crocante inferior a 0,3. As bananas foram trazidas da cidade de Registro (SP) e do município de Eldorado (SP) e utilizaram-se frutas com teor de sólidos solúveis nas seguintes faixas de °Brix: 18,9-19,5, 20,9-21,5 e 22,9-23,5. Nestas duas últimas faixas de °Brix, foram realizados ensaios de secagem em duplicata com bananas de Eldorado, e para bananas originárias de Registro, foram realizados ensaios em duplicata nas três faixas, totalizando 10 ensaios. Na matéria-prima foram determinados os teores de açúcares totais, açúcares redutores, amido, lipídios, cinzas e proteínas, enquanto que no produto final foi analisada a textura por método instrumental, determinando-se a força máxima e o número de picos do gráfico força versus tempo obtido em teste de força à velocidade constante. Além disso, a matéria-prima e a banana crocante foram submetidas à análise de cor instrumental, na qual foram determinados os parâmetros a*, b* e L* referidos como o sistema CIELAB. No geral, a matéria-prima de Eldorado apresentou maior teor de amido, lipídios e proteína e menor umidade, e era mais amarela e escura que a banana de Registro. Em termos de desenvolvimento da cor caramelo, encolhimento da estrutura, ocorrência de puffing e escurecimento, a operação de secagem que produziu a banana crocante de melhor qualidade foi composta pela seguinte seqüência de etapas: HTST (150°C por 18 min) + redução gradual de temperatura (50 min) + secagem a 70°C. O tempo total desta operação até que o produto final atingisse aw<0,3 variou de 7-9h, e os valores obtidos para aw final foram entre 0,18 e 0,29. As curvas típicas de textura dos snacks apresentaram inúmeros picos, chegando à contagem de 54, caracterizando assim a propriedade de crocância. Estatisticamente, a procedência, o grau de maturação e os teores de açúcares totais e redutores foram significativos para a crocância. Os parâmetros de cor foram afetados significativamente apenas pelos açúcares redutores e proteínas
Abstract: In order to be consumed as a snack, crispy dried banana can be produced through the process of drying using high temperature for a short time (HTST - High Temperature Short Time) during the initial stage, followed by drying with an average temperature (50- 70°C). The aim of this study was to evaluate the effect of the chemical composition of banana nanica (Musa acuminata Colla subgrupo Cavendish), which was grown in two different regions and presenting three ripening stages, upon the crispness and color of final product, which was obtained by using a HTST stage at 150°C. The end of the process was pointed by the dried banana water activity being less than 0,3. The fruits were brought from the cities Registro (SP) and Eldorado (SP) and, the ones used had the following ranges of soluble solids content (°Brix): 18,9-19,5; 20,9-21,5 e 22,9-23,5. With bananas presenting the latter two °Brix ranges, dryings were performed in duplicates with bananas from Eldorado, whereas for the fruits originated in Registro, dryings were executed in duplicates using all the three °Brix intervals, comprising the total of 10 runs. The following contents in the raw material were determined: total sugar and reducing sugars, starch, fat, ash and protein, whereas the final product was evaluated by an instrumental texture analysis (maximum force and number of peaks in the force versus time graph obtained in force tests at constant velocity). Moreover, the raw material and final product underwent an instrumental color analysis, in which the parameters a*, b* e L* referred as the CIELAB system, were determined. Generally, the raw material from Eldorado presented higher starch, fat and protein content and less water, and it was also more yellow and darker than the one from Registro. In terms of the development of brown color, structure shrinkage, puffing and darkening, the drying operation that produced a crispy banana with the best quality comprised the following stage sequence: HTST (at 150°C for 18 min) + gradual reduction of temperature (50 min) + drying at 70°C. The total time of this operation until the final product reached aw<0,3 varied from 7 to 9h, and the values obtained for the final aw were between 0,18 and 0,29. The typical texture graphs of the snacks showed several peaks, up to 54, which characterizes crispness. Statistically, the plantation site, ripening stage and total and reducing sugar contents were significant. The color parameters were statistically affected only by reducing sugars and proteins
Mestrado
Mestre em Engenharia de Alimentos

Este trabalho investigou a previsão do tempo de secagem de uma massa cerâmica à base de argila vermelha, proveniente de uma indústria situada na região de Gravataí-RS. O material foi misturado nas composições de 0%, 5% 8% e 10% em peso em relação à argila de sua chamota (queima a 950°C), e caracterizado quanto à composição química, mineralógica e granulométrica. À massa cerâmica foi adicionada água até o limite de plasticidade mais 3% (base seca), sendo, então, homogeneizada, conformada por extrusão (a vácuo) e submetida à secagem por convecção em uma atmosfera psicrometricamente controlada As condições praticadas são as típicas de processos de secagem industrial: temperaturas de 40ºC, 50ºC e 60ºC, umidade relativa de 40% e velocidade do ar de 1,5 m/s. Para tanto, foi desenvolvido um aparato experimental de bancada que controlou, monitorou e registrou as perdas de massa (água) em tempo real. Foram elaboradas curvas de perda de massa pelo tempo e determinada a umidade crítica, através das diferenciais da perda de massa pelo tempo baseando-se nas curvas de Bigot e calculada a velocidade de perda de massa instantânea. Foram determinadas curvas de regressão linear, e a estimativa do tempo de secagem, em função da temperatura do ar de secagem e da quantidade de chamota. Os corpos-de-prova foram ainda caracterizados em função de sua resistência mecânica, cuja variação foi quantizada pela estatística de Weibull. Foram realizados 30 ensaios para cada conformação, sendo que para cada batelada foram utilizados três corpos-de-prova por ciclo de secagem. Os resultados mostraram que à medida que se aumenta a proporção de chamota e a temperatura de secagem, aumenta a velocidade de secagem, tendo como consequência a diminuição do tempo de secagem. Esses fenômenos foram equacionados de acordo com cada formulação, servindo de base para um modelo de estimativa do tempo de secagem de argilas, nas mesmas condições aqui retratadas. Isso permite uma previsão de maneira otimizada, do tempo que o material fica submetido à secagem, antes do início do processo de queima, tendo como consequência economia de energia e tempo quando de sua utilização no processo industrial.
This study investigated the prediction of the drying time of a ceramic-based red clay, from an industry located in the region of Gravataí-RS .. The material was mixed in the compositions of 0% 5% 8% and 10% by weight in relation to its chamotte clay (firing at 950 ° C), and characterize d for chemical composition, mineralogical and particle size. In the ceramic body water was added to the plastic limit plus 3% (dry basis), and then homogenized, formed by extrusion (vacuum) and subjected to convective drying in a controlled environment psychrometric conditions applied are the typical industrial drying processes: temperatures of 40 º C, 50 º C and 60 º C, relative humidity of 40% and air velocity of 1.5 m / s. To this end, we developed an experimental apparatus who managed, monitored and recorded losses of mass (water) in real time. They have been drawn curves of mass loss over time and determined the critical moisture through the differential mass loss by the time in the Bigot curves and calculated the speed of instant weight loss. We determined linear regression curves and the estimation of drying time, depending on the temperature of the drying air and the amount of chamotte. The samples were further characterized according to their strength, whose variation was quantized by the statistical Weibull. 30 tests were performed for each conformation, and for each batch were used three bodies of test by drying cycle. The results showed that as increasing the proportion of chamotte and the drying temperature increases the drying rate, resulting in the decrease of drying time. These phenomena were equated according to each formulation serving of base for a model to estimate the drying time of clay under the same conditions depicted here, with an estimated optimally, the time that the material is subjected to drying before the beginning of the burning process of firing process, resulting in savings and time when its use in industrial process.

A aplicação da técnica de leito de jorro na secagem de pastas têm sido objeto de inúmeras investigações nos últimos anos, devido a possibilidade de obtenção de produtos de alta qualidade em uma operação de reduzido custo. No presente trabalho, avaliou-se a influência dessa técnica sobre as características e o desempenho de liberação de microcápsulas contendo diferentes fármacos modelo. Microcápsulas de caseína-pectina contendo indometacina e paracetamol foram preparadas por coacervação e posteriormente secas por leito de jorro e por spray drying. Após a secagem por leito de jorro, verificou-se uma redução na quantidade de indometacina recuperada a partir das microcápsulas. Não se observou segregação do fármaco durante a operação de secagem por leito de jorro, indicando que a reduzida recuperação do mesmo foi resultado do estabelecimento uma interação fármaco-polímero, a qual ocorre especificamente entre a caseína e a indometacina. A avaliação físico-química desses materiais indicou que a interação proposta possui natureza covalente e os estudos in vivo de atividade antiinflamatória das microcápsulas contendo indometacina mostraram a irreversibilidade dessa ligação em ambiente biológico. A metodologia de estímulo resposta foi avaliada e otimizada para a determinação do tempo de residência das microcápsulas em leito de jorro. Apesar de confiáveis, os valores de tempo de residência obtidos não puderam ser correlacionados à formação da interação fármaco-polímero, por se apresentarem estáveis quando da variação das condições operacionais do secador. Por outro lado, a vazão e a temperatura do ar de secagem mostraram influência significante sobre a formação da referida interação. Posteriormente à investigação da interação indometacina-caseína, foi avaliada a funcionalidade das microcápsulas obtidas por leito de jorro e por spray drying. Para tanto, foram realizados estudos de liberação in vitro, os quais mostraram a similaridade entre os perfis de dissolução da indometacina do paracetamol independentemente do método de secagem empregado. Uma exceção está na formulação não reticulada contendo indometacina, que apresentou um elevado nível de ruptura após a secagem por leito de jorro. Os dados obtidos na avaliação da funcionalidade dos sistemas juntamente com a constatação experimental do maior aproveitamento energético na secagem por leito de jorro, permitem considerar que a utilização dessa técnica na secagem de microcápsulas é promissora, visto que a interação fármaco-polímero discutida nesse trabalho é específica e dependente do tipo de fármaco encapsulado
The use of spouted bed technique in the drying of paste has been subject to many researches in the past years due to the possibility of obtaining high quality products at low cost. In present work the influence of this technique on microcapsule drug delivery systems performance was evaluated. Casein-pectin microcapsules with entrapped indomethacin and acetaminophen were prepared using the complex coacervation method. Thereafter the coacervates were dried using the spouted bed and spray drying techniques. After spouted bed drying an interaction between indomethacin and casein was observed, with reduction of drug recovery from microcapsules. The mass balance studies showed the absence of indomethacin segregation during spouted bed drying, which indicates drug-polymer interaction. This interaction was not observed for acetaminophen. The physico-chemical evaluation suggests that the indomethacin interaction had covalent nature and in vivo studies showed its stability under enzymatic biological conditions. The microcapsule residence time during spouted bed drying was determined using a validated and optimized stimulus response method. Despite the reliable results obtained it was not possible to determine the influence of residence times on drug-polymer interaction due to the stability of those values with operational conditions. On the other hand air temperature and air flow rate during spouted bed drying affected significantly the degree of drug polymer interaction. In order to evaluate the spouted bed and spray dried microcapsule?s performance a dissolution study was performed. The results showed very similar drug release, with exception for the non-crosslinked formulations dried in spouted bed. These microcapsules were ruptured by spouted bed mechanical stresses. The results obtained on the microcapsules performance evaluation and the characteristics of thermal efficiency and high evaporative capacity of spouted bed demonstrate the potential application of casein-pectin spouted bed drying

Byggandet av dagens sjukhus har blivit allt mer komplext. När det kommer till uppbyggnaden av stomkonstruktionen har kraven för vibrationer ökat. För att säkerställa kraven för stomvibrationer måste pågjutningens tjocklek öka med ca 90 mm från standarden som är ca 40 mm. Att utföra denna extra pågjutning är inte ett problem i sig, utan den extra torktiden som tillkommer. Den extra torktiden är inte det enda problemet. De beräkningsprogram som finns ute på marknaden idag kan inte behandla alla typer av konstruktioner och simuleringar, dock skulle det kunna gå att dela upp simuleringsprocessen för uttorkningen emellan beräkningsprogrammen. I denna studie så kommer två olika simulering/beräknings program att tillämpas. Beräkningsprogrammen som kommer att användas är TORKA S och WUFI. Torktiderna kommer att räknas fram genom att kombinera dessa program samt titta på tidigare studier gällande detta projekt. I denna studie har vi valt att ta en närmare titt på hur foggjutningen mellan håldäcken påverkar torktiden för hela delområdet, dvs. foggjutningen och pågjutningen. Resultaten visar att vct för foggjutningen måste vara betydligt lägre än vct för pågjutningen och att torktiderna varierar beroende på vct. Torktiderna för pågjutningen varierar om mätningar görs över fog eller mitt på håldäcken.
Constructions of hospitals today have become more complex than before. As for the construction of the frame structure, the requirements for vibration in the body have increased. To fulfill the requirements for frame vibrations the top coating thickness must be increased with 90 mm ​​from the standard thickness, which is around 40 mm. To perform this extra topping is not the biggest issue. The major problem is the extra drying time that is added in the process. Another large problem is the calculation programs that are available on the market today cannot deal with all types of designs and simulations; however it would be possible to divide the simulation process for the dehydration between different calculation programs. In this study, two different simulation/calculation programs will be used. The programs that will be applied are TorkaS 3.2 and WUFI Pro. Drying times will be generated by combining these programs and look at previous studies similar to this project. In this study we have chosen to take a closer look at how joint cast between the slabs affects the drying time for the entire sub-area, which is the joint cast and topping cast. The results of the w/c-ratio for joint cast must be significantly lower than w/c-ratio for topping and that drying times will vary depending on the w/c-ratio. Drying times for topping will also vary if measurements are made over the joint or middle of the slab.

Vid gjutning av bostadsbjälklag är formbyggnad och stämprivning ett viktigt moment. Inombyggbranschen råder vissa tveksamheter angående när och hur stämpen skall rivas. Instruktioner förhur det skall gå till finns att tillgå men de är ofta svårtolkade och i viss mån utdaterade. Det leder tillatt de i många fall inte följs. Hjälpmedel som mätinstrument och simuleringsprogram för detta finnsmen används sparsamt. För att undvika olyckor och säkerställa att betongens hållfasthet är tillräckligutan hjälpmedel används överdrivna tidsmarginaler och detta leder sannolikt till att stämp blirståendes längre än vad som krävs.Under arbetets gång studeras stämp och gjutningsprocessen i detalj för att kunna skapa en tydligbild över hur de ingående faktorerna vid valvgjutningar påverkar varandra. Syftet är att föreslå enlämplig tidpunkt för stämprivning vid valvkonstruktioner. Detta utförs för att kunna avgöra ifall detfinns någon större förbättringspotential, dels när det gäller att motverka slösaktighet av resurser ochförbättra arbetsmiljön men även för att se över instruktionerna för tillvägagångssättet vidformrivning.De metoder som används för att nå resultatet är:● Litteraturstudie av de dokument som beskriver tillvägagångssättet vid stämprivning.● Mätningar med instrument som beräknar hållfasthet vid gjutningar av bostadsbjälklag.● Simuleringar av hållfasthet i programmet Hett 11.● Intervjuer av sakkunniga inom branschen.Resultatet av studien visar på stora skillnader mellan hur länge stämpen står i praktiken och hurlänge de enligt teorin behöver stå. En anledning till detta är att uttorkningstiderna är styrande underproduktionen. Detta medför att högre betongkvaliteter och snabbare härdningstider än de somprojekterades används i byggandet, speciellt vid låga temperaturer. Slutsatsen är att det finnsförbättringspotential inom området. Säkerhetsstämpning kan utföras endast ett par dagar eftergjutning vid goda förhållanden. Fördelarna med detta är att antalet stämp kan minskas, vilket ledertill minskade hyror, samt att framkomligheten för kommande yrkesgrupper och arbetsmoment kanförbättras.
When casting a residential floor, formwork and shore removal is an important element. There aresome doubts in the industry about when and how to remove the shores. There are instructionsavailable but they are often outdated and difficult to interpret. As a result, they are often notfollowed. Appliances such as measuring equipment and simulation software are available but areused sparingly. To avoid accidents and to ensure that the strength of the concrete is sufficientwithout appliances, excessive time margins are used. This will most likely result in unnecessarily longshoring times.During the course of the work, the subject will be studied in detail to create a clear picture of howthe many different factors of the casted floor influence each other. The purpose is to propose asuitable time to remove the shores. This is done in order to determine if there is improvementpotential, partly to improve the working environment, but also to review the instructions of theapproach.The methods used to reach the result are:• Study of the documents describing the procedure of shoring and reshoring• Calculate the compressive strength of the concrete with the device “BI Distant”• Simulate the compressive strength of the concrete in the program Hett 11.• Interviews by experts in the industry.The results show that the shores could theoretically be removed earlier compared to when they areusually removed in practice. One reason for this is that drying times are governing during theproduction. This means that increased concrete qualities and faster curing times than those thatwere planned, were used in construction, particularly at low temperatures. The conclusion is thatthere is an improvement potential in this area. Reshoring can be done only a few days after castingunder good conditions. The advantages of this are that the number of shores can be reduced. Thisleads to reduced rents, and the accessibility for the subsequent professionals and operations can beimproved.

La maîtrise du procédé séchage, étape essentielle dans la transformation du bois, est devenue incontournable pour la filière bois. Cette thèse propose l'utilisation de conduites de séchage oscillantes pour réduire les contraintes de séchage liées au retrait par l'activation du fluage mécanosorptif. A ce jour, la meilleure façon d'appliquer les conduites oscillantes représente un défi pour la communauté scientifique. Dans ce travail, nous avons choisi comme matériel d'étude une essence feuillue fortement utilisée dans la filière et très susceptible aux déformations lors du séchage : le hêtre (Fagus sylvatica). L'effet des conduites oscillantes sur les contraintes de séchage est étudié par une approche expérimentale et par une approche théorique, articulées en trois parties : - Un premier volet expérimental sur un séchoir semi – industriel pour saisir l'effet global des conduites oscillantes à l'échelle d'une pile de planches. L'amélioration de la qualité du bois séché s'est avérée par : une meilleure homogénéité de la teneur en eau finale inter et intra-planche, la diminution des déformations globales et la diminution des contraintes résiduelles exprimées par le gap du « slicing test ». - Ensuite, nous avons développé un volet théorique sur la base de modélisations analytique et numérique pour étudier l'évolution des champs de teneur en eau et de contraintes mécaniques au sein d'une planche lorsque les conditions climatiques oscillent. Une formulation analytique simple, adaptée aux conduites oscillantes, est proposée pour les utilisateurs de séchoirs n'ayant pas accès à un outil numérique sophistiqué. L'approche numérique effectuée avec l'outil de simulation TransPore permet une étude plus réaliste du séchage oscillant. Ainsi, le module mécanique de TransPore a été utilisé pour dégager des configurations pertinentes de séchage permettant d'étudier l'effet des conduites oscillantes sur la relaxation des contraintes. - Enfin, un second volet expérimental a été réalisé sur un séchoir de laboratoire, à l'échelle d'une planche, pour tester les informations issues du volet théorique. Un dispositif de séchage dissymétrique (flying wood) et deux dispositifs de séchage sous charge (poutre cantilever et flexion trois points) ont été utilisés pour étudier l'effet des oscillations. Toutefois, ces essais ne permettent pas de montrer clairement l'effet des oscillations sur la relaxation des contraintes. La confrontation entre les résultats expérimentaux à l'échelle d'une planche et la simulation numérique a mis en évidence l'effet conséquent des oscillations parasites de faibles période et amplitude sur les résultats expérimentaux, provoquées par la régulation du séchoir. Des modifications du modèle de comportement mécanique différé ont été proposées en perspectives de ce travail afin de mieux saisir le comportement observé expérimentalement
Wood drying is an essential process in the wood industry. A perfect control of wood drying is nowadays very important for the wood industry. In this study, we propose the utilization of oscillating drying conditions to reduce the drying stresses induced by wood shrinkage by activating the mechanosorptive creep. The best way to apply this concept remains an open question in the scientific community. Beech wood (Fagus sylvatica), one of the most commonly used hardwood in France, was chosen for this study owing its elevated risk of drying defaults. The effect of oscillating conditions on drying stresses inside the boards was studied by both an experimental and a theoretical approach, structured in three parts: - A first experimental part realized with a semi – industrial kiln in order to study the global effect of oscillating conditions at the stack scale. Improvement of the quality of dried wood was showed by the best homogeneity of water content inside the board and among the boards and by the decrease of global deformations and residual stresses expressed by the gap measured by the slicing test. - The study was continued with a theoretical part based on analytical and numerical modeling to understand the development of internal heat and mass transfers inside the boards and the evolution of drying stresses during oscillating conditions. A simple analytical model adapted to the oscillating conditions was proposed, particularly for kiln users who don't have access to sophisticated numerical tools. The numerical approach used the simulation tool TransPore, able to simulate oscillating drying in more realistic conditions. Its mechanical module was used to set accurate drying schedules to study the effect of oscillating conditions on stresses relaxation. - Finally, a second experimental part was performed in a laboratory scale kiln, at the board scale, to test the information obtained theoretically. A non-symmetrical drying device (flying wood) and two different loaded drying devices (cantilever beam test and three points bending) were used to study the effect of oscillations. However, it is difficult to see the oscillating conditions effect on the stresses relaxation. The confrontation between experimental results at the board scale and the numerical simulation showed the significant effect produced on experimental results by parasite oscillations of small periods and intensities, originated by the kiln regulation. Further work should consider some modifications of the time dependent mechanical behavior model in order to capture the experimentally observed behavior

La torréfaction est un traitement thermique à basse température (250 à 300 °C) en atmosphère inerte qui permet de modifier les propriétés de la biomasse. La biomasse torréfiée est alors plus dense énergétiquement, plus hydrophobe et plus fragile. Dans cette étude, un modèle numérique de torréfaction en four tournant à une dimension a été développé. Le transport des plaquettes de bois, les transferts thermiques, le séchage ainsi que les cinétiques de torréfaction ont été modélisés séparément. Après confrontation aux résultats expérimentaux, ces différents sous-modèles ont été assemblés dans un modèle global. Le modèle prédit alors l’évolution de la température et de la perte de masse des plaquettes le long du four. Les résultats numériques montrent une adéquation satisfaisante avec les valeurs obtenues lors d’expériences de torréfaction sur un four tournant pilote. Les solides torréfiés ont été analysés et leurs propriétés ont été corrélées à la perte de masse. Il a en particulier été démontré que l'énergie de broyage de la biomasse torréfiée était fortement réduite
Torrefaction is a thermal treatment at low temperature (250-300°C) used to improve biomass properties. Torrefied biomass has a higher energy density, it is more hydrophobic and more brittle. In this study, a one-dimensional numerical model of torrefaction in a rotary kiln has been developed. The wood chips flow, the thermal transfers, the drying step and the torrefaction kinetics have been modelled separately. These submodels have been experimentally validated before being implemented together. The model can thus predict the temperature and the mass loss of wood chips along the kiln. These results are in good agreement with values obtained during torrefaction experiments in the pilot-scale rotary kiln. In parallel, torrefied biomass has been analysed in terms of composition, heating value and structural properties with emphasis on the decrease of grinding energy consumption

Le séchage est une opération incontournable pour la valorisation énergétique des boues résiduaires. La flexibilité pour ajuster la teneur en matière sèche finale de la boue est un critère important pour le choix d'une technologie. Cet objectif est difficile à atteindre pour les sécheurs à palettes. La modélisation du processus est alors essentielle. Malheureusement, le comportement rhéologique des boues est complexe et la mécanique des fluides numérique est hors de portée. La notion de Distribution des Temps de Séjour est employée ici pour caractériser l'écoulement. Un protocole fiable et reproductible a été établi et mis en œuvre sur un pilote de laboratoire. Des injections Dirac d'oxyde de titane et de sels métalliques, avec la spectrométrie de fluorescence X comme méthode de détection, ont été employées pour caractériser les DTS du solide anhydre et de la boue humide. Pré-Mélanger la boue pâteuse, pour disperser le traceur par exemple, modifie la structure du matériau. Ceci a été mis en évidence par des mesures de distribution en taille des particules et par des caractérisations rhéologiques. Cependant, des expériences de séchage en batch ont montré que ce pré-Mélange n'a aucune influence sur la cinétique et sur la phase plastique. Nous avons montré que le solide anhydre et le solide humide s'écoulent de la même manière. Une seconde méthode, basée sur une détection par conductimétrie, a alors été développée. Plus facile à mettre en œuvre et moins onéreuse, cette méthode s'avère tout aussi fiable que la première. L'influence de la durée de stockage de la boue, avant séchage, a été évaluée. Le temps de séjour de la boue dans le sécheur double quand la durée de stockage passe de 24h à 48h. Finalement, un modèle d'écoulement, basé sur la théorie de chaînes de Markov, a été développé. L'écoulement du solide anhydre est décrit par une chaîne de n cellules parfaitement mélangées, n correspondant au nombre de palettes. Les probabilités de transition entre les cellules sont régies par deux paramètres : le ratio de recyclage interne, R, et la masse de solides retenus, MS. R est déterminé par la relation de Van der Laan et MS est identifié par ajustement du modèle aux données expérimentales. Le modèle décrit de manière satisfaisante les DTS. La masse de solides retenus identifiée est toujours plus faible que la quantité mesurée expérimentalement. Une partie de la boue, collée aux parois du sécheur et au rotor, agit comme un volume mort
Drying is an unavoidable operation prior to sludge valorization in incineration, pyrolysis or gasification. The flexibility to adapt the solid content of the dried sludge to the demand is a major requirement of any drying system. This objective is difficult to reach for paddle dryers. Modeling the process is thus essential. Unfortunately, sludge rheological behavior is complex and computational fluid dynamics is out of reach for the time being. The concept of Residence Time Distribution (RTD) is used here to investigate sludge flow pattern in a paddle dryer. A reliable and reproducible protocol was established and implemented on a lab-Scale continuous dryer. Pulse injections of titanium oxide and of salt metals, with X-Ray fluorescence spectroscopy as detection method, were used to characterize the RTD of anhydrous solid and wet sludge, respectively. Premixing the pasty sludge, for tracer powder dispersion for instance, changes the structure of the material. This was highlighted through the measurements of particle size distributions and characterization of rheological properties. However, drying experiments performed in batch emphasized that premixing does not have any influence on the kinetic and the sticky phase. The RTD curves of the anhydrous solid are superimposed on those of the moist sludge. Consequently, a simpler protocol, based on pulse injection of chloride sodium and offline conductivity measurements, was established. Easier to implement in industry and cheaper, this method proves to be as reliable as the first one. The influence of storage duration prior to drying was assessed. The mean residence time doubles when the storage duration changes from 24h to 48h. Finally, a model based on the theory of Markov chains has been developed to represent the RTD. The flow of anhydrous solids is described by a chain of n perfectly mixed cells, n corresponding to the number of paddles. The transition probabilities between the cells are governed by two parameters: the ratio of internal recirculation, R, and the solids hold-Up, MS. R is determined from the Van der Laan's relation and MS is identified by fitting the model to the experimental RTD. The model describes the flow pattern with a good accuracy. The computed hold-Up is lower than the experimental one. Part of the sludge is stuck to the walls of the dryer, acting as dead volumes in the process

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
O arroz é um dos principais cereais produzidos e consumidos no Brasil e no mundo. A maior parcela do grão cultivado pertence ao arroz de pericarpo marrom, porém nos últimos anos tem crescido a procura dos consumidores a grãos que apresentem o pericarpo pigmentado devido principalmente aos benefícios proporcionados pelos mesmos a saúde. O arroz é colhido com umidade elevada sendo a secagem uma etapa fundamental para a manutenção da qualidade e do valor nutritivo do produto. Objetivou-se, no primeiro estudo, avaliar os efeitos imediatos e latentes provocados pelo tempo de espera para a secagem (imediata, 3 e 6 dias), bem como a temperatura de acondicionamento do material durante o período de espera (15° e 25°C) sobre os principais indicadores da qualidade do produto armazenado durante 12 meses. Os resultados deste primeiro estudo, mostram que o perfil colorimétrico dos grãos sofre alterações significativas como consequência das variações provocadas pelo tempo de espera para a secagem em compostos fenólicos e proantocianidinas. As propriedades químicas, físicas, industriais e de cocção dos grãos também são alteradas negativamente em função do tempo de espera, porém o arrefecimento da massa atenua os seus efeitos. Um segundo estudo teve por objetivo avaliar os efeitos imediatos e latentes da temperatura (40°, 60°, 80° e 100°C) empregada na secagem, realizada em secador de leito-fixo, bem como avaliar os efeitos da secagem natural, ao sol e, da secagem intermitente em escala industrial, sobre os principais parâmetros de avaliação da qualidade desses grãos durante 12 meses de armazenamento. Os resultados obtidos no segundo estudo indicam que a utilização de altas temperaturas na secagem provocam distúrbios fisiológicos e causam alterações negativas nos parâmetros químicos, físicos, industriais e de cocção dos grãos. Os compostos bioativos são afetados negativamente nos grãos submetidos a secagem na temperatura de 100°C. A utilização de temperaturas iguais ou inferiores a 60°C melhor preservaram o valor nutritivo e as qualidades industriais e de cocção dos grãos.
Rice is one of the main cereals produced and consumed in Brazil and the world. Most of the grain grown belongs to the brown pericarp rice, but in the last years the demand of the consumers has been increased to the grains that present the pigmented pericarp due mainly to the health benefits provided by them. The rice is harvested with high humidity and drying is a key step in maintaining the quality and nutritional value of the product. The objective of this study was to evaluate the immediate and latent effects caused by the waiting time for drying (immediate, 3 and 6 days), as well as the material storage temperature during the waiting period (15 ° and 25 ° C) on the main indicators of product quality stored for 12 months. The results of this first study show that the colorimetric profile of the grains undergoes significant changes as a consequence of the variations caused by the waiting time for drying in phenolic compounds and proanthocyanidins. The chemical, physical, industrial and cooking properties of the grains are also negatively altered due to the waiting time, but the cooling of the mass attenuates its effects. A second study aimed at evaluating the immediate and latent effects of temperature (40 °, 60 °, 80 ° and 100 ° C) used in drying in a bed-fixed dryer, as well as to evaluate the effects of natural drying, sun and intermittent drying on an industrial scale on the main parameters of evaluation of the quality of these grains during 12 months of storage. The results obtained in the second study indicate that the use of high temperatures in drying causes physiological disturbances and causes negative changes in the chemical, physical, industrial and cooking parameters of the grains. The bioactive compounds are adversely affected in the beans subjected to drying at a temperature of 100 ° C. The use of temperatures equal to or less than 60 ° C better preserved the nutritional value and the industrial and cooking qualities of the grains.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
To study the dispersion of the coffee fruits during the drying, a vibrated tray drier with recycle was used. The dryer consists basically of four sections: drying vertical tunnel, vibration system, system of warm air supply to the drying tunnel and recycle system of coffee fruits. The drying tunnel contains four perforated trays through which the coffee fruits and air flow out, in cross flow. The coffee fruits drying was carried out using two experimental design, where the studied variables were, for the first design: coffee fruits temperature (40; 45 and 50ºC); mass of coffee fruits (11.5; 12.5 and 13.5 kg) and air mass rate (7; 8 and 9 kg air/min); the varieties of coffee fruits were: Acaiá, Catuaí and Mundo Novo; and for the second design: mass of coffee fruits (10; 12 and 14 kg) and air mass rate (7; 8 and 9 kg air/min), with coffee fruits temperature around 45ºC and the coffee variety Mundo Novo. For the first experimental design, the coffee fruits temperature only influenced significantly the drying time, where the largest temperature level reduces in 26.77 h the drying time. For the second experimental design, the studied variables were not significant on drying time. Coffee fruit sphericity, density, sticky decreased with the decrease of the moisture content. With reference to the quality of coffee grain, the best operational conditions were obtained with greater coffee fruits mass and air mass rate. The coffee fruits flow in the drying tunnel is promoted by vibration of the trays coupled to electromagnetic vibrators. The vibration amplitude was determined by an accelerometer connected to a signal conditioner and an analogical oscilloscope. The vibration amplitude decreased with the reduction of the coffee fruits moisture content due to the shrinkage and decrease of the mass, sticky, density and particle size coffee fruits. The coffee fruits mass rate and the residence time distribution were determined (RTD), during the drying. At the end of the drying, the flow occurs with easiness due to: absence of sticky of the coffee fruits; decrease of the particle mass and particle vibration damping decrease, due to particle rigidity acquired in the drying. The dispersion coefficient (Ez) was determined by Taylor Dispersion Model, Free Dispersion Model and Modified Free Dispersion Model. For the great majority of the experiments, the model that better fitted the experimental data (greater coefficient of correlation) was the model of the Modified Free Dispersion. The dispersion coefficient (Modified Free Dispersion) ranged from 1.31×10-4 to 68.67×10-4 m2/s. The Péclet number ranged from 1.15 to 31.00.
Para estudar a dispersão dos frutos de café durante a secagem, utilizou-se um secador de bandejas vibradas com reciclo. O secador consiste basicamente de quatro seções: túnel vertical de secagem, sistema de vibração, sistema de injeção de ar aquecido no túnel de secagem e sistema de reciclo dos frutos de café. O túnel de secagem contém quatro bandejas perfuradas por onde escoam os frutos de café e o ar, em fluxo cruzado. A secagem dos frutos de café foi realizada utilizando-se dois planejamentos experimentais, onde as variáveis estudadas foram, para o primeiro planejamento de secagem: temperatura dos frutos de café (40; 45 e 50ºC); massa de frutos de café alimentada (11,5; 12,5 e 13,5 kg) e vazão de ar de secagem (7; 8 e 9 kg ar/min), a variedade dos frutos de café foram: Acaiá, Catuaí e Mundo Novo; e para o segundo planejamento de secagem: massa de frutos de café (10; 12 e 14 kg) e vazão de ar (7; 8 e 9 kg ar/min), mantendo-se a temperatura dos frutos em 45ºC e a variedade Mundo Novo. Para o primeiro planejamento somente a temperatura dos frutos influenciou significativamente o tempo de secagem, onde o maior nível de temperatura reduz em 26,77 h o tempo de secagem. Para o segundo planejamento as variáveis estudadas não foram significativas para o tempo total de secagem dos frutos de café. Durante a secagem ocorre encolhimento dos frutos de café, diminuição da esfericidade, da pegajosidade, da densidade aparente e aumento da área superficial específica com a diminuição do conteúdo de umidade dos frutos de café. Em relação à qualidade do grão de café, as melhores condições operacionais foram obtidas com maior massa e maior vazão de ar de secagem. O escoamento do café no túnel de secagem é promovido pela vibração das bandejas acopladas a vibradores eletromagnéticos. A amplitude de vibração foi determinada por um acelerômetro acoplado a um condicionador de sinal e a um osciloscópio analógico. A amplitude vibracional diminuiu com a diminuição da umidade dos frutos de café devido ao encolhimento e à diminuição da massa, da pegajosidade, da densidade e do diâmetro dos frutos de café. Durante a secagem foram determinadas a vazão mássica dos frutos de café e a distribuição do tempo de residência (DTR). Ao final da secagem, o escoamento dos frutos de café ocorre com maior facilidade devido a: ausência de pegajosidade dos frutos de café; diminuição da massa das partículas e redução do amortecimento da vibração dos frutos de café devido à rigidez adquirida na secagem. O coeficiente de dispersão (Ez) foi determinado pelos modelos da Dispersão de Taylor, da Dispersão Livre e da Dispersão Livre Modificado. Para a grande maioria dos experimentos, o modelo que melhor se ajustou aos dados experimentais (maior coeficiente de correlação) foi o Modelo da Dispersão Livre Modificado. O coeficiente de dispersão dos frutos de café variou de 1,31×10-4 a 68,67×10-4 m2/s. O número de Péclet variou de 1,15 a 31,00.
Doutor em Engenharia Química

Ce travail de thèse concerne les verres bioactifs purs et dopés pour des applications en tant que biomatériaux en site osseux. Ils sont synthétisés par fusion dans le système SiO₂-CaO-Na₂O-P₂O₅. Quatre éléments métalliques (Zn, Ti, Cu et Ag), présentant des caractéristiques chimiques et physiologiques intéressantes, ont été introduits dans la matrice vitreuse. Leur réactivité chimique et leur cytotoxicité ont été évalués lors de tests in vitro. L'introduction de ces éléments métalliques influe sur les caractéristiques thermiques des verres ainsi que sur la dissolution de la matrice vitreuse, la cinétique et la cristallisation de la couche d'hydroxyapatite. Une bonne prolifération cellulaire a été mise en évidence. En parallèle, une méthode de synthèse d'une vitrocéramique, présentant une microporosité, a été développée par réaction entre TiN et ZnO. Des essais in vitro ont montré un caractère bioactif après 60 jours d'immersion et une absence de cytotoxicité. Ce biomatériau a ensuite été implanté au niveau de la diaphyse fémorale de lapins. Différentes études structurales ont montré la résorption progressive du biomatériau jusqu'à 6 mois d'implantation. Des scaffolds chitosan / verre bioactif ont également été synthétisés et obtenus par lyophilisation. Ils ont été étudiés lors d'essais in vitro. Ils ont servi de support pour la vectorisation de gentamicine. Les résultats obtenus montrent que les teneurs en chitosan et en verre bioactif ont une influence sur la cristallisation de l'hydroxyapatite et le relargage du médicament. Les modèles mathématiques établis montrent que le temps de relaxation des scaffolds dépend de la concentration de départ en gentamicine
This research work focuses on the pure and doped bioactive glasses for use as bone biomaterial. They are synthesized by the melting method in the system SiO₂-CaO-Na₂O-P₂O₅. Four metallic elements, presenting interesting chemical and physiological properties, have been introduced in the amorphous matrix. Their chemical reactivity and their cytotoxicity have been evaluated during in vitro assays in simulated body fluid and cell culture media. The introduction of these metallic elements influences their thermal characteristics, the glass matrix dissolution, the kinetic and the crystallization of the hydroxyapatite layer. A good cells proliferation have been showed. In parallel, a method of synthesis of a glass-ceramic, having a microporosity, have been developed by reaction between TiN and ZnO. In vitro assays have showed a bioactive character after 60 days of immersion and a non-cytotoxicity. This biomaterial was implanted in the femoral dyaphisis of rabbits. Different structural studies have showed the gradual resorption of the biomaterial up to 6 months of implantation. Finally, scaffolds chitosan/bioactive glass, obtained by freeze-drying, have also been studied during in vitro assays. They were used as support for the vectorization of gentamicin. The obtained results show that the content of chitosan and bioactive glass have an impact on the crystallization of hydroxyapatite et the release of drug. Mathematic models show that the relaxation time depend on the starting concentration of gentamicin

Cette thèse propose une approche hiérarchique du diagnostic des systèmes complexes par décomposition en sous-systèmes élémentaires de diagnostic puis agrégation de ceux-ci. Le chapitre 1 décomposition en sous-systèmes élémentaires de diagnostic puis agrégation de ceux-ci. Le chapitre 1 détaille la problématique du diagnostic en temps réel ainsi que celle des systèmes complexes. Il en propose une solution par décomposition hiérarchique et présente l'outil logiciel dialogs issu de ce concept. Il présente enfin un système complexe illustrant cette approche. La station d'épuration de Maxéville et son séchage thermique des boues. Les chapitres 2 et 3 abordent l'aspect modulaire de cette approche au travers de l'étape de génération de symptômes. Le chapitre 2 propose pour cela des méthodes de détection de défauts permettant, de générer des symptômes indépendants. Le chapitre 3 présente des techniques plus élaborées assurant également la localisation de défauts au travers d'ensemble de symptômes. La nécessité d'associer les résidus fournis par ces méthodes dans des niveaux de décision hierarchiquement supérieurs impose leur homogénéisation au moyen de tests de décision présentes chapitre 2. Le chapitre 4 développe les notions de hiérarchisation et d'agrégation de systèmes élémentaires au travers de deux méthodes de localisation de défauts, la décision structurée et la décision à objectifs multiples. Une troisième technique, la décision générique, permet de conclure quant à l'état du système complet

Detta examensarbete har gjorts på uppdrag av Skanska Teknik med handledning av Johan Sjödin. Arbetets syfte var att jämföra olika limträförband, utförda av antingen spikningsplåtar eller WT-T skruvar, och komma fram till den bästa lösningen med hänsyn till bärförmåga, kostnad och utförandetid. I ett projekt har de spikningsplåtar, som används vid limträförband, börjat rosta under extremt fuktiga förhållanden fastän spikningsplåtarna är rostfria enligt tillverkaren. En fördel med WT-T skruvar är att de är gömda inne i träet och på så sätt inte i direkt kontakt med den aggressiva miljön, men även skyddad mot brand. Andra fördelar med WT-T är att utförandetiden är kort och kostnaden är lägre än spikningsplåtsalternativet. Ett experiment har gjorts för att undersöka hur träet med inborrade WT-T skruvar beter sig under uttorkning.

This diploma work was made under commission by Skanska Teknik, with guidance by Johan Sjödin. The purpose of this work was to compare different gluelam joints, performed by nailing plates or WT-T screws, and find out the best solution with regard to carrying ability, cost and performance time. In a certain project have the nailing plates, which are used in gluelam joints, corroded under extremely damp circumstances although the nailing plates are rust free according to the manufacturer. An advantage with WT-T screws is that they are hidden inside of the tree and in that way not in directly contact with the aggressive environment, but also protected against fire. The other advantages with WT-T screws are that the performance time is short and the cost is lower than the nailing plates-alternative. An experiment has been carried out to investigate how the tree with WT-T screws behaves itself during drying period.

Hyaluronan is a chemical, which can be qualified as essential for vertebrates. It is a part of the extracellular matrix in most of tissues and also a major component of some other tissues. Besides of the mechanical functions this compound is important for many biological processes such as growth of tumor cells. The objective of this thesis was development of carrier systems containing native hyaluronan and hydrophobic drugs. For purposes of this work fluorescence probes (pyrene, prodan, perylene, DPH, mereocynine 540) instead of drugs were used. By using further mentioned sophisticated methods the properties of these systems were studied. The systems were prepared by freeze-drying. The effect of freeze-drying on support of interactions was observed by fluorescence spectrometry (steady-state and time-resolved). The stability of freeze-dried systems was determined by zeta potential, which was measured by electrophoretic light scattering. Cakes obtained by freeze-drying were analyzed by several methods. First one was effluence gas chromatography connected with FT-IR spectrometry. In this method the present of tertiary butyl alcohol in product was observed. The cakes were also analyzed by scanning electron microscopy, which can provide the information about the surface and elemental constitution of the material. The results of this work can shed light on the area of developing of drugs with targeted distribution of active compound.

Large volumes o f relatively small-diameter logs are generated from sustainable sources such as the Pacific Coast Hemlock second-growth forests. The percentage of juvenile wood in this kind of material is higher compared to limited old growth wood supplies. The present scientific knowledge is often limited to individual properties of juvenile wood without including interactions with other drying factors. For that reason, this investigation evaluates the drying quality of the mix of 105 mm square timbers from second-growth western hemlock (Tsuga heterophylla) and amabilis fir (Abies amabilis), commercially known as Pacific Coast Hemlock baby-squares, using two different concepts of interactions. First, the evaluation is based on the influence of juvenile wood presence shown with a pith location at their end-surface and drying target moisture content, while in the second concept the cutting season is added as the third controlled factor. Timber specimens were classified into four groups depending on the presence and location of the tree pith. A total of 640 specimens were dried in a laboratory conventional (heat-and-vent) kiln in four drying runs to 15% and 20% target moisture contents, with one charge of specimens from the summer and other of the fall cutting season. The results showed that timbers with the pith shown in the centre should be avoided in the production of baby-squares because of its high propensity for bow, twist and surface checks, due to the problems with variable shrinkage coupling of juvenile and mature wood within specimens. Specimens with the pith shown close to one of the sides in the cross-section had a lower, but acceptable, quality according to the El20 CFLA grading rules. Because of the higher shrinkage, the lower target moisture content shows a greater risk for twist and surface checks, compared with the higher moisture content. The importance of the cutting season is reflected through its significant interactions with the target moisture content in the case of volumetric shrinkage, and with the pith location in the case of twist. These are consequences of lower initial moisture content in summer-cut specimens that could occasionally reach moisture content below the fiber saturation point, and start to shrink before kiln drying.
Forestry, Faculty of
Graduate

This study investigated the potential of pre-treatment techniques to produce high quality back-sawn boards from regrowth messmate stringybark (Eucalyptus obliqua L'Herit), which is very prone to collapse and checking. Saturated urea solution, one percent sodium hydroxide, four percent acetic acid, water, urea formaldehyde resin (UF), and polyvinyl acetate glue (PVA) were used. In Chapter 4, the experiment of chemical soaking pre-treatments showed that soaking in sodium hydroxide solution for up to 15 days caused almost double increase of boards' drying rate. However, this technique and soaking in acetic acid solution caused more collapse and checks. In Chapter 5 and 6, the surface coating experiment confirmed that coating with UF resin did not significantly improve the drying properties of the boards. In contrast, PVA coating prevented surface checking and considerably reduced edge checking and collapse. The check value of these P boards was only a quarter the check value of control boards. In Chapter 6, the pre-treatments trial proved that significant reductions of shrinkage and collapse were achieved mainly by urea soaking for eight weeks (SSW boards). Both tangential and radial shrinkages of S8W boards were less than half the shrinkages of control boards. The collapse free boards of S8W were almost double amount of that in control boards. However, this pretreatment caused more surface checks. One-day urea soaking followed by eight weeks close stacking (C treatment) reduced checking. The check free boards of C, W, and P were 38%, 25%, and 88%, while that of the control, S8W, and S2W boards were the same, 19%. The average drying rates of W, S8W, and S2W boards were respectively 1.3 times, 0.4 times, and 0.6 times the drying rate of the control boards. The average drying rates of P and C boards were almost the same as that of control boards (1.7 x 10-2 %/hour, in a four month drying trial). This study indicates the prominent benefit of PV A surface coating in improving the quality of dried back-sawn timber of regrowth messmate stringybark. Further research, combining PV A coating and different drying process, such as high temperature drying, is needed to produce high quality dried timber in a much shorter time. This study also recommends water soaking when collapse and check prone timbers cannot be kiln-dried immediately after sawing.

A detailed investigation of the air flow through a timber stack with the flow both along and across the board is described. Measurements of velocity profile and turbulence level at various distances from the leading edge are presented to show the structure and development of the boundary layer flow under various free stream velocities. Existing theories on the laminar separation at entrance and the transition process from laminar to turbulent flow in the separated shear layer and the development of the boundary layer flow are examined and compared with experiments. Surface shear stress and friction factor are estimated from the measurement of the static head drop and boundary layer properties along the flow passage. These are used to predict heat and mass transfer coefficients with the Reynolds analogy between heat, mass and momentum transfers. A simplified model based on the concept of "free water" and "bound water" sharply separated by a fibre saturation point (FSP) is proved to be a useful concept for conveying preliminary idea but not sufficiently accurate for a detailed understanding of the drying of Tasmanian eucalypt timbers. Experimental evidence of surface temperature changes during drying and the formation of dry patches has led to an approach based on detailed measurements of the boundary layer flow and a coupled heat and mass transfer model within the boundary layer. In the model, the transfer of moisture within the wood is assumed to be a diffusion process in which the diffusion coefficient is independent of the moisture content and the driving force is the moisture concentration as in true molecular diffusion. The transfer of heat is modelled by considering the convective heat transfer over the board surface and the conduction heat transfer inside the board. The governing transport equations are solved numerically based on analytical solutions. The model has been validated by measuring moisture contents of slices of boards during drying. Successful drying of Tasmanian eucalypt timber from green to EMC with the test procedure outlined in the process of research is made for the quarter-sawn boards. The effect of edge drying on the overall drying behaviour of the whole board is shown and the analytic solution of the two dimensional diffusion equation is quoted. A literature survey on the mechano-sorptive effect is made as entry to the subject. Tests with the Tasmanian peppermint eucalypt timber are conducted under bending conditions and the stresses are applied in the direction across the grain. It is shown that nearly linear relationships could be fitted between the average moisture content and mechano-sorptive effect of the wood over the whole moisture content range, but the slope of the line changes at about FSP. The slope of the line also appears to be dependent upon the initial moisture content and temperature of the wood. It is also shown that change of the loading direction from along grain to across grain results in a large increase in the mechano-sorptive effect.

This study was aimed at exploring the effect of oscillating the drying temperatures of a drying schedule on the drying characteristics of thick western hemlock timbers. Pacific coast hemlock which is comprised of about 70% western hemlock (Tsuga heterophylla (Raf.) Sarg.) is one of the best quality and most abundant softwood species along the coast of British Columbia. The squares of 105 x 105mm of this species group is widely used for housing construction in Japan, and mostly imported from British Columbia. In recent years the overall demand has decreased and there is also a great market shift in demand from green to kiln-dried lumber. However, conventional kiln-drying of thick hemlock timbers has difficulties of long drying times, uneven final moisture content distribution within and between lumber, honeycombs, checking and splitting. Since most industries still use conventional dry kilns (also known as "heat-and-vent" kilns), it is imperative to explore alternative drying schedules to improve the quality of 105mm square dried Pacific coast hemlock. In this study, thick industrial size square Pacific coast hemlock of dimensions 115 x 115 x 920 mm were dried in a laboratory conventional kiln, using a control schedule and four oscillating drying schedules with drying temperatures (wet bulb –T[sub wb]=53°C, dry bulb-T[sub db]=60°C) oscillating at two amplitude and frequency combinations (3°C/4hours and 6°C/8 hours). The research results indicated that, the total effect of oscillating schedule on drying rate was more pronounced at the early stages of the drying process. Oscillating dry bulb temperatures at higher amplitudes increased drying rate by 12%, whereas the lower amplitude counterpart reduced kiln residence time by 14%. All schedules were also found to reduce moisture content variability between lumber. Core and shell moisture content variation slightly decreased when the wet bulb temperature was oscillated at low amplitudes. Climate oscillations also affect the drying stresses of thick hemlock lumber. Drying stresses in the lumber increased when oscillating the dry bulb temperature at lower amplitudes. Width shrinkage in the baby square hemlock lumber reduced in the low amplitude dry bulb oscillated schedule.
Forestry, Faculty of
Graduate

Einleitung: Die Leptospirose ist eine der weltweit bedeutendsten Zoonosen. Durch den häufig asymptomatischen oder unspezifischen Krankheitsverlauf, wird von einer hohen Dunkelziffer ausgegangen. Menschen können sich über direkten Tierkontakt oder indirekten Kontakt mit dem Urin infizierter Tiere, zum Beispiel über kontaminierte Gewässer oder Erde, anstecken. Die Infektion erfolgt dabei über den Eintritt des Erregers in Schleimhäute oder Hautwunden. Ziel der Untersuchungen: Obwohl die Überlebenszeit von Leptospiren in der Umwelt einen entscheidenden Einfluss auf das Infektionsrisiko des Menschen hat, wurden bisher nur sehr wenige Untersuchungen dazu durchgeführt. Diese konzentrierten sich dabei vor allem auf das Überleben der Erreger in Erde oder Wasser. Daher war es Ziel dieser Arbeit die Umweltstabilität eines häufig in Deutschland gefundenen Leptospirenserovars unter verschiedenen Umweltbedingungen zu untersuchen. Zusätzlich zu diesen Untersuchungen war es Ziel dieser Arbeit, durch die Veröffentlichung eines Übersichtsartikels über die Leptospirose Ärzte in Deutschland für diese häufig unerkannt bleibende Erkrankung zu sensibilisieren. Material und Methoden: Ein jahrelang an Kulturmedium adaptierter Labor- und ein erst vor 3 Jahren isolierter Feldstamm von Leptospira kirschneri Serovar Grippotyphosa wurden auf ihr Überleben in der Umwelt untersucht. Es wurde ihre Widerstandsfähigkeit gegenüber verschiedenen Umwelteinflüssen, wie z.B. Tierurin als umgebendes Medium bei verschiedenen Temperaturen oder auch der Einfluss einer Trocknung, untersucht. Nachdem die Leptospiren den Umwelteinflüssen für unterschiedliche Zeitspannen ausgesetzt waren, wurde versucht sie in EMJH-Medium wieder zu kultivieren. Während einer Inkubationszeit von mindestens 28 Tagen bei 29 °C wurden diese Kulturen wöchentlich unter dem Dunkelfeldmikroskop auf das Vorhandensein motiler Leptospiren untersucht. Zusätzlich wurde durch Kultivierungsversuche in EMJH-Medium das Überleben der Leptospiren in einem Wasserstrom mit einer definierten Fließgeschwindigkeit und ihre Verbreitung in diesem Strom mittels real-time PCR untersucht. Alle Versuche wurden im Dreifachansatz durchgeführt. Statistische Untersuchungen wurden mittels eines zweiseitigen Mann-Whitney-U Tests (Fehler 1. Art α = 0,05) durchgeführt. Ergebnisse: Die beiden untersuchten Stämme von L. grippotyphosa überlebten nicht in unverdünntem Tierurin. In verdünntem Tierurin überlebten die Stämme, je nach Temperatur und Verdünnungsmedium, zwischen 1 - 72 Stunden (Laborstamm) und 4 - 24 Stunden (Feldstamm). Beide Stämme überlebten signifikant länger bei 15 °C als bei 37 °C (p < 0,001, bzw. p = 0,041). Der Laborstamm überlebte signifikant länger in verdünntem Rindereurin (max. 72 h bei 15 °C) als in verdünntem Hundeurin (max. 4 h; p = 0,027). Im Gegensatz dazu, überlebte der Feldstamm signifikant länger in Hundeurin (max. 24 h bei 15 °C) als in Rinderurin (max. 4 h; p = 0,028). Das vollständige Trocknen auf einer festen Oberfläche war bei Temperaturen zwischen 15 °C und 37 °C für beide Stämme letal. Jedoch war, unabhängig von der untersuchten Temperatur, eine halbe Stunde vor der vollständigen Trocknung eine Kultivierung der Leptospira spp. noch möglich. In einem Wasserstrom konnten sich die Leptospiren aufgrund ihrer Eigenbewegung schneller und langsamer als die Durchschnittsgeschwindigkeit (0,01 m / s) des Wassers bewegen, überlebten jedoch die mechanischen Schäden während des Schlauchdurchflusses nicht. Schlussfolgerungen: Das Überleben von Leptospira spp. ist offensichtlich von vielen Faktoren abhängig. Eine schnelle Verdünnung nach der Ausscheidung mit dem Urin scheint dabei essentiell zu sein. Niedrigere Temperaturen sowie eine feuchte Umgebung verbessern ihre Widerstandsfähigkeit gegen schädliche Einflüsse, während Trockenheit oder mechanische Schädigung ihr Überleben nicht ermöglichen. Wegen der großen Bedeutung der leptospiralen Überlebenszeit in der Umwelt für das Infektionsrisiko von Mensch und Tier sind weitere Untersuchungen auf diesem Forschungsgebiet in der Zukunft nötig.:1. Einleitung 2. Literaturübersicht 2.1 Die Geschichte der Leptospirose 2.2 Morphologie und Übertragungswege der Erreger 2.3 Taxonomie 2.4 Haupt- und Nebenwirte 2.5 Die Erkrankung beim Menschen 2.5.1 Vorkommen 2.5.2 Klinik und Therapie 2.6 Die Erkrankung beim Tier 2.6.1 Bei Nutztieren 2.6.2 Bei Haustieren 2.6.3 Bei Wildtieren 2.7 Diagnostik 2.8 Die Umweltstabilität der Erreger 2.8.1 In Erde 2.8.2 In Wasser 2.8.3 In Urin 3. Publikationen 3.1 Publikation Nr. 1 3.2 Publikation Nr. 2 4. Diskussion und Schlussfolgerung 5. Zusammenfassung 6. Summary 7. Literaturverzeichnis 8. Danksagung
Introduction: Leptospirosis is one of the most important zoonosis worldwide. Due to the often asymptomatic or non-specific course of the disease, a high number of unreported cases is assumed. Humans can get infected through direct contact with animals or indirect contact with the urine of infected animals, for example through contaminated water or soil. The infection occurs via entry of the pathogen through mucous membranes or skin wounds. Aims of the study: Although the survival time of Leptospira spp. in the environment has a crucial influence on the human infection risk, very few studies have been carried out so far. These studies focused primarily on the survival of the pathogens in soil or water. It was therefore the aim of this study to investigate the environmental stability of a leptospiral serovar that is frequently found in Germany under different environmental conditions. In addition to these investigations, the aim of this work was to raise the awareness of physicians in Germany for this often undetected and neglected disease by publishing a review article on leptospirosis. Material and Methods: The survival in the environment of both a laboratory strain, which has been adapted to culture medium for years and a field strain, which was isolated only 3 years ago, of Leptospira kirschneri Serovar Grippotyphosa was studied. Their resistance to various environmental influences, such as animal urine as surrounding medium at different temperatures or the influence of drying, were examined. After the leptospires were exposed to these influences for various time periods, an attempt was made to cultivate them in EMJH medium. During an incubation period of at least 28 days at 29 °C, the cultures were examined weekly for the presence of motile leptospires under the darkfield microscope. In addition, the survival of the leptospires in a water stream with a defined velocity and their distribution in this stream were examined by real-time PCR and cultivation experiments in EMJH medium. All experiments were carried out in triplicate. The statistical analysis was done using a two-tailed Mann-Whitney U test (type-1-error α = 0.05). Results: Both examined strains of L. grippotyphosa did not survive in undiluted animal urine. In diluted animal urine, the strains survived between 1-72 hours (laboratory strain) and 4-24 hours (field strain), depending on the temperature and dilution medium. Both strains survived significantly longer at 15 °C than at 37 °C (p < 0.001 or p = 0.041). The laboratory strain survived significantly longer in diluted cattle urine (max. 72 h at 15 °C) than in diluted dog urine (max. 4 h) (p = 0.027) while the field strain survived significantly longer in dog urine (max. 24 h at 15 °C) than in cattle urine (max. 4 h) (p = 0.028). Complete drying on a solid surface at temperatures between 15 °C and 37 °C was lethal for both strains. However, regardless of the temperature examined, Leptospira spp. were still cultivatable half an hour before the time point of complete drying. In a water stream, leptospires were able to move faster or slower than the average velocity of the water (0.01 m / s) due to their intrinsic mobility but were not able to survive the mechanical damage caused by running water in the hose system. Conclusions: Overall, it can be concluded that the survival of Leptospira spp. depends on many factors. Rapid dilution after urine excretion appears to be essential. Lower temperatures and a humid environment improve their survival time, while drought or mechanical damage is lethal to them. Because of the great importance of leptospiral survival in the environment for the infection risk of humans and animals, further studies in this research area will be necessary in the future.:1. Einleitung 2. Literaturübersicht 2.1 Die Geschichte der Leptospirose 2.2 Morphologie und Übertragungswege der Erreger 2.3 Taxonomie 2.4 Haupt- und Nebenwirte 2.5 Die Erkrankung beim Menschen 2.5.1 Vorkommen 2.5.2 Klinik und Therapie 2.6 Die Erkrankung beim Tier 2.6.1 Bei Nutztieren 2.6.2 Bei Haustieren 2.6.3 Bei Wildtieren 2.7 Diagnostik 2.8 Die Umweltstabilität der Erreger 2.8.1 In Erde 2.8.2 In Wasser 2.8.3 In Urin 3. Publikationen 3.1 Publikation Nr. 1 3.2 Publikation Nr. 2 4. Diskussion und Schlussfolgerung 5. Zusammenfassung 6. Summary 7. Literaturverzeichnis 8. Danksagung