Global ETD Search

31	The Effects of Species, Adhesive Type, and Cure Temperature on the Strength and Durability of a Structural Finger Joint Vrazel, Matthew Eric 03 August 2002 (has links) This research project was conducted to evaluate the effects of adhesive type, wood species, and cure temperature on the strength and durability properties of a finger joint. The adhesives were a resorcinolormaldehyde(RF),polyurethane/aqueous emulsion polymer (PU/AEP), and a resorcinolormaldehyde/soy-isolate honeymoon system. The species of wood were keruing (Dipterocarpus spp.), southern pine (Pinus spp.), and Douglasir (Pseudotsuga menziesii). The cure temperatures of the adhesives were ambient (26-35° C, 78-95° F) and elevated (43-49° C, 110-120° F). Joints were subjected to three test procedures; a tension test, a bending test, and a bending test following an accelerated aging procedure. The response variables measured for each of the bending tests included modulus of rupture, modulus of elasticity, and percent wood failure. The response variables measured for the tension tests were tensile strength and percent wood failure. The RF adhesive performed the best in flexural and tensile strength of the three adhesives studied. However in most cases, the PU/AEP adhesive could be considered a comparable system. Given adequate adhesive performance, strength and stiffness of the joints studied were dependent on density of the wood species, with keruing having the greatest density. finger joint end joint structural wood adhesives keruing southern pine Douglasir resorcinolormaldehyde polyurethane soy hydrolyzate aqueous emulsion polymer
32	Decay and environmental studies on southern pine Dahlen, Joseph Martin 10 December 2010 (has links) This work focused on decay and dimensional stability of southern pine lumber and environmental issues associated with emissions released during kiln drying of southern pine. In one study decking boards were treated with a 3% resin acid solution to increase the dimensional stability. The boards were placed on a roof and weathered for two years. The increased water repellency reduced moisture gain following summer rainstorms by one-third compared to untreated matched samples, this significantly reduced splitting by half and cupping by one-third. In one study decking boards from matched samples were weathered for two years in the roof setup described above, and in a fungal ground proximity test. The ground proximity samples had slightly more decay than the roof samples. Correlation between decay ratings for the matched samples was 37%, suggesting above-ground decay susceptibility is dependent on the macro- and micro-environment. Decay in roof exposure was modeled based on moisture content factors, whereas decay in ground proximity was modeled by the resin and fatty acids. One study tested pole sections with varying amounts of sapwood, heartwood, and knots dried in a pilot-scale kiln. A sample of the kiln exhaust was measured for volatile organic compounds. Emissions from poles were similar to clear lumber. Emissions from heartwood poles were less than for heartwood lumber, perhaps due to the poles’ sapwood band. The final study was conducted with clear and knotty lumber kiln dried to below 8% moisture content using three kiln schedules. Wood dried to this lower moisture content is used in interior applications or exported. During drying, a sample of the kiln exhaust was analyzed for total VOCs, and a sample of the kiln exhaust was collected and analyzed for hazardous air pollutants via gas chromatography and spectrophotometry. For all three kiln schedules, mills would reach 10 tons of methanol and thus must comply with maximum achievable control technology standards before reaching 25 tons of methanol, formaldehyde, acetaldehyde, acrolein, and propionaldehyde. Southern pine tall oil rosin dimensional stability decay biodeterioration emissions volatile organic compounds hazardous air pollutants formaldehyde methanol utility poles
33	Nondestructive assessment of flexural and tensile properties for southern pine structural lumber Carmona Uzcategui, Marly Gabriela 09 August 2022 (has links) (PDF) The flexural and tensile properties of visually graded southern yellow pine lumber were modeled. Longitudinal and transverse vibration techniques and proof-loading bending tests were used to assess the flexural and tensile properties of southern pine lumber. The properties evaluated were dynamic modulus of elasticity (dMOE), static modulus of elasticity (Eb), tension modulus of elasticity (Et), and ultimate tensile stress (UTS). The tensile properties were evaluated in the direction parallel to the grain. This study presents the results of tests conducted on No. 2 2 × 6 and 2 × 10 southern pine lumber of two different lengths (14 ft. and 16 ft.). The results of the analysis show that nondestructive testing techniques are excellent to assess Et and Eb. Moderate relationships were found between dMOE and UTS and between Eb and UTS. Improvements in the prediction of UTS were done with the inclusion of additional parameters into the model. The combination of dMOE, density, and frequency domain area (FDA) generated the highest coefficient of determination for UTS. The distributions of flexural and tensile properties were analyzed for the goodness of fit. Normal distribution was found for Eb data whereas the lognormal distribution was the best fit for the tensile properties. bending modulus of elasticity tensile properties longitudinal vibration transverse vibration southern pine structural lumber Other Forestry and Forest Sciences Wood Science and Pulp, Paper Technology
34	MY EYES DUE SEE Barfield, Johannes J 01 January 2018 (has links) My Eyes Due See is a multidimensional examination of the “black experience” in America. The installation is composed of a single-channel video, a music composition that utilizes music samples and live instrumentation, and sculptures made up of car parts and broomsedge grass. Each of these elements arranged in space share a nuanced and complicated view of blackness through the lens of a black man decoding personal history and American history simultaneously. Autonomy is the overarching theme throughout the work as it pertains to race, identity, urban and rural environments, and the relationship between generational trauma and nostalgia. Johannes James Barfield Johannes Johannes Barfield Barfield my eyes due see black video artist black artist road street asphalt fluorescent lights fluorescent forensic rod forensic trajectory rod rods automotive car parts road marking tape broomsedge ballistic trajectory rods grass objective reasonableness amplification nullification southern pine asphalt impregnated board Audio Arts and Acoustics Composition Fine Arts Interdisciplinary Arts and Media Other Film and Media Studies Sculpture
35	Implementing the circularly polarized light method for determining wall thickness of cellulosic fibres Edvinsson, Marcus January 2012 (has links) The wall thickness of pulp fibers plays a major role in the paper industry, but it is currently not possible to measure this property without manual laboratory work. In 2007, researcher Ho Fan Jang patented a technique to automatically measure fiber wall thickness, combining the unique optical properties of pulp fibers with image analysis. In short, the method creates images through the use of an optical system resulting in color values which demonstrate the retardation of a particular wave length instead of the intensity. A device based on this patent has since been developed by Eurocon Analyzer. This thesis investigates the software aspects of this technique, using sample images generated by the Eurocon Analyzer prototype. The software developed in this thesis has been subdivided into three groups for independent consideration. First being the problem of solving wall thickness for colors in the images. Secondly, the image analysis process of identifying fibers and good points for measuring them. Lastly, it is investigated how statistical analysis can be applied to improve results and derive other useful properties such as fiber coarseness. With the use of this technique there are several problems which need to be overcome. One such problem is that it may be difficult to disambiguate the colors produced by fibers of different thickness. This complication may be reduced by using image analysis and statistical analysis. Another challenge can be that theoretical values often differ greatly from the observed values which makes the computational aspect of the method problematic. The results of this thesis show that the effects of these problems can be greatly reduced and that the method offers promising results. The results clearly distinguish between and show the expected characteristics of different pulp samples, but more qualitative reference measurements are needed in order to draw conclusions on the correctness of the results. Pulp paper optics polarization image analysis log-normal wall thickness coarseness douglas fir cedar SPF southern pine eurocon analyzer ho fan jang Software Engineering Programvaruteknik Atom and Molecular Physics and Optics Atom- och molekylfysik och optik Computational Mathematics Beräkningsmatematik Other Computer and Information Science Annan data- och informationsvetenskap Engineering and Technology Teknik och teknologier
36	Bolstering Pine Lumber Value Through Statistical Analysis And Nondestructive Testing Owens, Frank Charles, IV 11 August 2017 (has links) In or around 2010, a nationwide reevaluation of the allowable properties for southern pine dimension lumber was initiated. This led to a 2013 reduction in the design values of visually graded southern pine dimension lumber and a resulting decrease in its commercial and utility value. This change compelled researchers and industry professionals to ponder what could be done to shore up the value of solid-sawn southern pine products going forward and potentially increase design values if appropriate. In pursuit of this question, this dissertation looks closely at three areas: 1) the possibility this reduction in mechanical performance is not merely limited to southern pine structural lumber but can also be observed in other solid-sawn softwood products and species, 2) flaws that might exist in commonly utilized statistical models for estimating allowable properties in lumber, and 3) the feasibility of using existing technologies to begin to compensate for the economic and/or utility losses attributed to the recent reduction in design values. This work is comprised of an introduction, a conclusion, and three independent content chapters utilizing a variety of statistical techniques to investigate whether strength and stiffness reduction might also be occurring in southern pine (and Douglasir) utility crossarms, evaluate the propriety of using a Weibull distribution model for estimating allowable properties in dimension lumber, and gauge the suitability of nondestructive testing methods for potentially identifying high-value premium grades in solid-sawn softwood products. bivariate Gaussian-Weibull distribution mixed bivariate normal distribution skew normal distribution 3-parameter beta distribution 2-parameter Weibull distribution mixed normal distribution normal distribution grading nondestructive Douglasir southern pine modulus of rupture modulus of elasticity bending stiffness mill run strength lumber Crossarms pseudo-truncated Weibull distribution lumber property distribution

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