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1
McCurdy, Murray Charles. "Efficient Kiln Drying of Quality Softwood Timber." Thesis, University of Canterbury. Chemical and Process Engineering, 2006. http://hdl.handle.net/10092/1097.
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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.
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Wendel, Charlotta. "Multivariate modeling improves quality grading of sawn timber." Thesis, Umeå universitet, Institutionen för fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-160765.
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The quality grades are what determines the value of sawn timber. Therefore the grading process is essential for the profitability of a sawmill. At a modern sawmill in northern Sweden, a CT Log Computed Tomography is used in the saw line to optimize the cutting solutions by virtual 3D reconstruction of the log features. By adjusting the position of the log according to the optimal solution before cutting, the aim is to increase the quality and final resale value of the sawn timber. However, measurement errors in the virtual and final grading systems cause inconsistencies that decrease the agreement in grading. The grading process uses a rule-based system based on the Nordic Timber Grading Rules, which depends strongly on the size and shape of knots. If knots are measured incorrectly they could falsely exceed the allowed value for a certain quality, resulting in an inaccurate quality grade. The results from this initial project, show that using multivariate modeling instead of the traditional rule-based grading system improves the agreement between the virtual and final grading. The accuracy in grading increases with up to 19%, resulting in an agreement of 73%. A better agreement between the two systems would allow the process to take advantage of the full potential of the CT, increasing the profitability of the sawmill. The results are promising, but before implementing the method in the sawmill further testing and development have to be done to ensure optimal improvement.
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Petersson, Hans. "Functions for predicting the quality of standing timber in Scots Pine /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1998. http://epsilon.slu.se/avh/1998/91-576-5343-7.gif.
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Hollabaugh, Eric M. "Field performance of instrumentation for monitoring effects of timber harvesting on water quality." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4541.
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Thesis (M.S.) University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 23, 2007) Includes bibliographical references.
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Höwler, Kirsten [Verfasser]. "Influence of intra- and interspecific competition on timber quality of European beech / Kirsten Höwler." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://d-nb.info/1225556007/34.
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Meade, Gregory S. "An evaluation of timber harvest planning training on logging quality in the Virginia Piedmont." Thesis, Virginia Tech, 1996. http://hdl.handle.net/10919/44970.
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Interest in BMP-related logger education and training has increased dramatically in recent years. Harvest planning is a critical component of forestry water quality BMPs. All states’ BMP manuals recommend written timber harvest plans, and several states require them by law. The objective of this study was to evaluate the impact of harvest planning training and the use of written timber harvest plans on BMP compliance, landowner satisfaction and weather-related downtime in the Virginia Piedmont. Nine randomly chosen loggers (study group) from the Virginia Piedmont participated in two days of intensive harvest planning field training. Nine additional loggers were randomly chosen as a control group. Study loggers prepared and followed written timber harvest plans for the 29 tracts they harvested during the 8-month study period immediately following the training. Study Group loggers outperformed Control Group loggers for mean BMP compliance (90% vs. 86%), mean landowner satisfaction (3.54/4.0 vs. 3.27/4.0), and mean weather-related downtime (10% vs. 13%). Absolute scores for all evaluation criteria for both groups were good, and differences, though statistically significant, were relatively small, leading to conclusions that:
• Loggers in the Virginia Piedmont are generally doing a good job.
• Loggers in the Virginia Piedmont are planning their operations, whether a written plan is required or not.
• Harvest planning training and written harvest plans can marginally improve BMP compliance, landowner satisfaction and weather-related downtime, even for loggers who are already performing well.Master of Science
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Maycock, Keith Michael. "The assessment of surface quality in planed and spindle moulded products." Thesis, De Montfort University, 1993. http://hdl.handle.net/2086/4088.
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Rust, Stephanus Marthinus. "Classification of timber from Pinus radiata trees exposed to forest fires." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/98097.
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Thesis (MSc)--Stellenbosch University, 2015.ENGLISH ABSTRACT: This study aimed to classify wood from trees that were exposed to forest fires with regards to their end use. Exposure to high temperatures over time is known to degrade wood in various ways. This degradation could limit the end use by altering mechanical, chemical and physical properties, leading to difficulty in processing or failing to meet required specifications for various grades. In this study wood from Pinus radiata trees that were exposed to forest fires of different levels of heat intensity was analysed with regards to its anatomical and physical changes. Trees were visually classified into three classes of burn severity. Moisture content measurements were taken from 135 standing trees, divided among the three classes. 30 trees, 10 from each of the three classes, were sampled and used for CT analysis. Samples were taken to include growth from before and after the fire. Two samples were taken from each tree, one from the charred and one from the uncharred side. The CT data was analysed and used to measure properties like growth ring width, cell wall thickness, lumen diameter and cell wall density. The data was used to compare properties from the charred and uncharred sides within a given year, as well as compare properties between years. The study showed that there were significant differences in the MC between the burnt and unburnt sides of trees from classes 2 and 3. The difference between the MC measurements on the burnt sides of three classes differed significantly from each other. Lightness measurements were taken on samples from classes 2 and 3. These samples showed no significant difference between the burnt and unburnt sides for either of the two classes. The samples from the less exposed class were lighter, but not significantly so. The macroscopic wood density was determined using core samples. A decrease in wood density was observed with an increase in fire exposure. The mean densities for all three classes however still fulfilled the requirements for structural timber set by the SABS. Growth ring width, cell wall thickness and lumen diameter analysis gave varied results, with some cases showing a decline in properties while others were seemingly unaffected. For many of the outcomes of this study, results found by previous studies could not be reproduced.
AFRIKAANSE OPSOMMING: Hierdie studie het gepoog om bome wat aan plantasiebrande blootgestel is volgens hul eindgebruik te klassifiseer. Dit is bekend dat blootstelling aan hoë tempreature hout in vele maniere afbreuk. Hierdie afbreuking kan die eindgebruik van die hout beperk deur die meganiese, fisiese en chemiese eienskappe sodanig te verander dat dit kan lei tot probleme met verwerking of ongeskiktheid vir sterktegrade. In hierdie studie is Pinus radiata bome wat aan plantasiebrande van verskillende grade blootgestel is ondersoek in terme van hul fisiese en anatomiese veranderinge. Bome is visueel in drie klasse van verskillende brandskade gegroepeer. Voglesings is op 135 staande bome, verdeel tussen die drie klasse, geneem. Monsters is van 30 bome, 10 uit elke klas, geneem vir CT analiese. Monsters is so geneem dat dit groei van voor en na die brand ingesluit het. Daar is twee monsters van elke boom geneem, een van die gebrande en een van die ongebrande kant. Die CT data is geanalieseer en gebruik om eienskappe soos jaarringwydte, selwanddikte, lumendiameter en selwand digtheid te meet. Die data is gebruik om eienskappe tussen die gebrande en ongebrande kante, sowel as tussen jare te vergelyk. Die studie het gewys dat daar noemenswaardige verskille is tussen die voginhoud van die gebrande en ongebrande kante van bome uit klasse 2 en 3. Die voginhoud van die gebrande kante van al drie klasse verkil ook noemenswaardig van mekaar. Ligtheidmetings is gedoen op monsters van klasse 2 en 3. Die monsters het nie ‘n noemenswaardige verskil tussen die gebrande en ongebrande kante getoon nie. Alhoewel die klas 2 monsters ligter vertoon het as die klas 3 monsters, was die verskil nie betekenisvol nie. Houtdigtheid is bepaal deur fisiese metings op die monsters wat vir die CT skandering gebruik is te doen. ‘n Daling in digtheid met ‘n toename in blootstelling aan die brand het duidelik na vore gekom. Die digtheid is egter nog hoog genoeg om aan die vereistes vir strukturele hout te voldoen, soos die die SABS bepaal. Jaarringwydte, selwanddikte en lumen diameter het wisselende resultate opgelewer, met sommige gevalle wat ‘n afname in eienskappe wys en ander wat ooglopend onveranderd was. Vir vele van hierdie uitkoms kon die resultate van vorige studies nie bevestig word nie.
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Mutabaruka, Celestin. "Investigation of factors affecting sweet chestnut (Castanea sativa Mill.) timber quality in relation to shake defect." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427822.
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Luca, Matthieu. "Quality Timber Strength Grading : A prediction of strength using scanned surface grain data and FE-analyses." Thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-14037.
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Koirala, Amod K. Bowders John J. "An evaluation of pre- and post-timber harvest water quality in low-order streams in the Missouri Ozarks." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6856.
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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 23, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. John J. Bowders, P.E. Includes bibliographical references.
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Worrell, E. Glen. "Loggers' perceptions of the costs of best management practices on timber harvesting operations in Virginia." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-08222008-063315/.
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Kelting, Daniel Ladd. "Timber Harvesting and Site Preparation Effects on Soil Quality for Loblolly Pine Growing on the Lower Coastal Plain of South Carolina." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/26842.
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The Lower Coastal Plain of the southeastern United States is a major wood producing region. The region is characterized by a combination of nearly-level topography, poorly-drained soils, and high rainfall, which results in a perched water table in some soils that inundates the surface several times each year. Harvesting timber under wet site conditions often results in extensive soil compaction, rutting, soil displacement, and waterlogging. Forest managers are concerned that these visually-displeasing soil disturbances may cause site damage and reduced productivity. These concerns were addressed in an operational-scale field experiment conducted in South Carolina. The objectives of this experiment were to determine: (i) if soil disturbance changes key soil properties and processes; (ii) if soil disturbance reduces loblolly pine productivity; and, (iii) if disturbance can be mitigated with site preparation practices? Three 20-ha, 20-yr-old loblolly pine (Pinus taeda L.) plantations were harvested under wet and dry conditions to create a broad gradient in soil disturbance. Within each harvested plantation, a subset of 3-ha plots were site prepared by either bedding, or mole-plowing plus bedding, then all sites were established as 3rd -rotation pine plantations. Prior to site preparation, each plot was classified and mapped using a 5 by 5 soil disturbance (none to churned) by organic debris (none to slash piles) classification matrix. Within each plot, data were collected on several soil physical, chemical, and biological properties over a 2-yr period following site preparation. Key soil properties were integrated into a Soil Quality Index (SQI) and compared to aboveground productivity of 2-yr-old loblolly pine trees growing on closely-spaced (30 by 30 cm) bioassay plots planted across the gradient of soil disturbance. The soil physical properties were used to determine the least limiting water range (LLWR), the range in soil water content within which root growth is not limited. Soil compaction and deep rutting reduced the LLWR. Retention of logging slash improved the LLWR for compacted and rutted soils. Site preparation improved the quality of the soil physical environment across all levels of soil disturbance. Soil disturbance had no effect on soil chemical or biological properties as evidenced by no change in soil pH, ECEC, base saturation, available P, or net N mineralization with disturbance. The base saturation exceeded 80 % on all sites, with Ca saturation controlling soil pH. The high base saturation buffered any redox-induced changes in soil chemistry that would have resulted from disturbance. The results showed that high fertility is an important mechanism for buffering the potentially-negative effects of soil disturbance on the soil nutritional environment. Site preparation changed soil chemical properties, but the changes were probably associated with tillage effects on organic matter and clay content, not redox processes. The SQI showed that surface soil compaction and deep rutting reduced soil quality, mainly by decreasing the LLWR and aeration depth. Site preparation mitigated the effects of most disturbances on soil quality, evidenced by similar aboveground biomass production among soil disturbance classes after bedding. A regression model was developed for predicting aboveground biomass production as a function of SQI. SQI explained 73 % of the variation in aboveground biomass production. The regression model showed that compression tracks and rutting decreased aboveground biomass production compared to undisturbed soils. The long-term effect of these disturbances on productivity will depend on natural soil recovery processes. However, these early results suggest that compaction and rutting should be minimized on similar sites, especially if sites will not be bedded before reforestation. The mole-plow / bedding treatment increased aboveground biomass production, indicating that this experimental treatment may be a viable practice for enhancing productivity.Ph. D.
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Jonsson, David. "Automatisk detektering av akustiska resonansfrekvenser i trästockar." Thesis, Uppsala universitet, Signaler och System, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-181499.
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In order to measure the quality of the logs, one can with help of Fast Fourier Transform technique get the signals resonance peaks. With help of these peaks you can see whether the quality of a tree is good or bad. This report contains the work of a where a program has been developed to be able to process a vibration created by an automatic hammer hitting on a log of wood. From the processed signal the program should be able to show both the raw wavesignal and the processed measured data from the resonance peaks. Beyond the raw wavesignal and resonance peaks the program should also be able to control the automatic hammer. The goal with the project is to have a program that get the same measure results as an already functioning measuring equipment. The result was a success when with the help of the program you were both able to control the hammer, measure the results and save the data with an accurate results.
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Woxblom, Lotta. "Warp of sawn timber of Norway spruce in relation to end-user requirements : quality, sawing pattern and economic aspects /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5860-9.pdf.
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Wessels, Coenraad Brand. "The variation and prediction of structural timber properties of standing Pinus patula trees using non-destructive methods." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86246.
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Thesis (PhD(For))--Stellenbosch University, 2014.ENGLISH ABSTRACT: Pinus patula is the most intensively planted conifer in the tropics and sub‐tropics. In South Africa Pinus patula plantations are the main saw‐log resource for structural lumber production. Improved intensive silvicultural practices and tree breeding have resulted in marked increases in the rate of growth. To reap the financial benefits of the faster growth, plantation managers are more and more inclined to reduce rotation ages, which inevitably results in the production of higher proportions of juvenile wood at final harvest, and lumber which often does not meet the minimum requirements for stiffness for structural lumber. Knowledge of the variation and the accurate prediction of the mechanical properties of the timber of standing trees can have various benefits for growers and processors of trees. It can be used for tree allocation to different processing facilities, for processing production planning, and to assist tree breeders to screen and select for superior breeding material. The objectives of this study were (1), to examine the within‐ and between‐tree variation in wood properties of young South African grown Pinus patula trees known to have important impacts on the suitability of sawn lumber for structural purposes and (2), to develop empirical prediction models for the flexural lumber properties from standing Pinus patula, based on variables that could be assessed non‐destructively from standing trees. Sample material was obtained from 170 trees (16‐20 years old) established in 17 compartments along the Mpumalanga escarpment of South Africa. A large number of variables which could be obtained non‐destructively from the trees while they were still standing, were measured. The trees were subsequently felled and two logs, 2.1 m in length, were extracted from each tree at two height positions. The 340 logs were processed into 1402 pieces of lumber for further measurements and destructive testing. Results showed that the mean modulus of elasticity measured on edge (MOEedge) was far below the limits set for structural grade softwood timber in South Africa. All the desirable properties for structural lumber improved with distance from the pith with the exception of the 5th percentile value for modulus of rupture (MOR), which was higher at the pith than for the boards processed adjacent to the pith. Boards processed from the lower part of the stem were superior in most of the important properties compared to those higher up in the stem. Separate multiple regression models for predicting the average dynamic MOE (MOEdyn) of individual boards, trees and compartments were developed. The models managed to explain 68%, 60% and 95% of the variation in MOEdyn respectively. The models developed for MOR explained 40% and 42% of variability at board and tree level respectively. At compartment level, 80% of the variation in the 5th percentile MOR value could be explained by the model. Sensitivity analyses showed that site index at base age of 10 years, acoustic time‐of‐flight, wood density and ring width were the most influential variables in the MOE models. The models indicated that tree slenderness during early growth seems to play a major role in determining the dynamic MOE and MOR of lumber. This is in agreement with Euler’s buckling theory and the bending stress theory. Microfibril angle (MFA) and density were measured on radial strips taken from a sub‐sample of trees with the Silviscan 3 technology. The mean microfibril angle per year ring in Pinus patula varied between 7o and 29o. In general MFA decreased with distance from the pith and height above ground level. A multiple regression model including microfibril angle, density and ring width explained 71% of the variation in the dynamic MOE of boards. Sensitivity analysis on the model showed that microfibril angle and density had roughly equal influences on predicting the MOEdyn of Pinus patula boards.
AFRIKAANSE OPSOMMING: Pinus patula is die mees aangeplante naaldhoutspesie in die tropiese en sub‐tropiese areas van die wêreld. Dit is die grootste bron van saagblokke vir die produksie van strukturele hout in SA. Intensiewe boskultuurpraktyke en boomteling het gelei tot ‘n merkbare verhoging in die groeitempo van die spesie. Plantasiebestuurders is gevolglik geneig om rotasie‐ouderdomme te verlaag, wat lei tot ‘n groter persentasie jeughout wat nie aan die minimum styfheidvereistes van strukturele hout voldoen nie. Kennis van die variasie en die akkurate voorspelling van die meganiese eienskappe van staande bome kan voordele inhou vir beide die verbouers en verwerkers van bome. Dit kan byvoorbeeld van hulp wees met die toewysing van bome aan verwerkingsfasiliteite, vir produksiebeplanning, en vir ondersteuning met die keuse van teelmateriaal vir boomtelers. Die doelwitte van hierdie studie was (1), om die binne– en tussenboomvariasie in die houteienskappe, wat ‘n bepalende invloed het op die geskiktheid van jong Suid Afrikaanse Pinus patula bome vir strukturele hout produksie, te ondersoek en (2), om empiriese modelle vir die voorspelling van die buigeienskappe van planke te ontwikkel, gebaseer op veranderlikes wat niedestruktief op staande Pinus patula bome ge‐evalueer is. Monsters vir die studie is verkry vanaf 170 bome (16‐20 jaar oud), geplant in 17 vakke op die Mpumalanga platorand van Suid Afrika. ‘n Groot aantal veranderlikes is nie‐destruktief gemeet op die staande bome waarna die bome gevel is en twee saagblokke, 2.1m in lengte, is op twee hoogte posisies uit elke boom verwyder. Die 340 blokke is verwerk tot 1402 planke vir verdere metings en destruktiewe toetse. Resultate het getoon dat die gemiddelde modulus van elastisiteit gemeet op die dwarskant (MOEedge) aansienlik laer was as wat vereis word vir strukturelegraad hout in Suid Afrika. Al die gewenste eienskappe het toegeneem met afstand vanaf die murg behalwe die 5de persentiel breekmodulus (MOR), wat hoër was vir murgplanke as vir aangrensende planke. Planke afkomstig van die laer dele van die stam het oor die algemeen beter eienskappe gehad as planke afkomstig van die hoër dele. Veelvuldige regressiemodelle kon 68%, 60% en 95% van die variasie in die gemiddelde dinamiese MOE (MOEdyn) op die vlak van onderskeidelik individuele planke, bome en vakke verklaar. Die modelle vir MOR kon 40% en 42% van die variasie op onderskeidelik plank‐ en boomvlak verklaar. Die model vir 5de persentiel MOR van vakke kon 80% van die variasie verklaar. ‘n Sensitiwiteitsanalise het aangetoon dat groeiplekindeks op ouderdom 10, akoestiese vlugtyd, digtheid en jaarringwydte die belangrikste veranderlikes was wat MOEdyn beïnvloed het. Die modelle het aangetoon dat die slankheid van bome tydens vroeë groei vermoedelik ‘n belangrike invloed op die MOEdyn en MOR van planke het. Dit is in ooreenstemming met Euler se knikteorie en die buigsterkteteorie. Die mikrofibrilhoek en digtheid van ‘n steekproef van die bome is gemeet met die Silviscan 3 apparaat. Die gemiddelde mikrofibrilhoek per jaarring het tussen 7 o en 29o varieer. Hierdie variasie was hoofsaaklik afhanklik van boomhoogte en aantal jaarringe vanaf die murg. ‘n Veelvuldige regressiemodel wat mikrofibrilhoek, digtheid en jaarringwydte insluit, kon 71% van die variasie in MOEdyn verklaar. ‘n Sensitiwiteitsanalise op die model het aangetoon dat mikrofibrilhoek en digtheid ongeveer ewe belangrik was wat betref hulle invloed op die voorspelde MOEdyn van Pinus patula planke.
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Lakel, William. "Effects of Forestry Streamside Management Zones on Stream Water Quality, Channel Geometry, Soil Erosion, and Timber Management in the Virginia Piedmont." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28619.
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The major study objectives include determining if a 50-foot streamside management zone (SMZ) as described in the Virginia BMP Manual (VDOF 2002) is generally sufficient to protect stream water quality, riparian soils, and stream bank integrity in headwater streams where forest harvesting has taken place, as well as comparing other SMZ widths with regard to the same environmental protection performance. In 2003, 16 forested watersheds were clear-cut harvested for commercial timber production. Four SMZ treatments were installed across four experimental blocks during harvest. Each of the 16 watersheds was subsequently site-prepared with prescribed burning and planted with loblolly pine (Pinus taeda). Within the watersheds, the established treatments were a 100-foot width with no thinning, a 50-foot width without thinning, a 50-foot width with thinning, and a 25-foot "stringer.â Each of the four treatments was conducted within three of four blocks (Incomplete Block Design). After a two-year post-harvest monitoring period, it was determined that the SMZ treatments had no significant effect on water quality, channel geometry, or soil erosion in and around the streams. There was no apparent water quality degradation as a result of harvesting timber, and larger SMZs did not have an impact on any of the parameters studied. It was also apparent that leaving narrower SMZs or thinning within SMZs did not cause any apparent environmental degradation. It was also determined that landowners who leave SMZs on their property have very limited opportunities to manage timber within them for financial gain in the long term.Ph. D.
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Alvskog, Kristina. "Rotstock av tall : Hur blir den framtida virkeskvaliteten?" Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-42911.
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För tallen finns många alternativa slutanvändningsområden, och kraven på virket varierar. Några egenskaper som har stor betydelse är stamrakhet, grengrovlek, grenvinkel och om det finns sprötkvist eller ej. Kvalitetsförsämringen i Sydsveriges tallskogar kan vara ett allvarligt problem och härör bl.a. till ökad produktion och rationaliseringar inom skogsbruket. Lönsamhet har varit målet, men har det skett på bekostnad av kvalitet? För att närmare belysa frågan om förekomsten av tall av god kvalitet syftar denna studie till att bedöma rotstockar i konventionellt skötta och stamkvistade bestånd samt deras potential att växa in i värdefulla klasser eller sortiment. Fältstudien är avgränsad till Bergslagen. I mätningarna har endast rotstock (upp till 3,4 m i längd) av träden bedömts, huruvida de har potential att hålla klass 1-kvalitet, sortiment stamblocks-kvalitet eller sortiment rotstock-kvalitet vid en brösthöjdsdiameter av 320 mm. Andelen rotstockar ≥ klass 1 uppskattades i de stamkvistade bestånden bli 72-94 %, då skötseln också syftat till en värdeökning. Andelen rotstockar ≥ klass 1 i de konventionellt skötta bestånden uppskattades bli 46-56 %. Med stor sannolikhet kommer ingen av dem dock få växa in i de värdefullaste klasserna. Vanligaste nedklassningssorsakerna är för många kvistar och ibland även i kombination med krök i de konventionellt skötta bestånden samt långkrök i de stamkvistade bestånden. I rapportens teori avhandlas olika sortiment och kvalitetsklasser, och sedan undersöks kvalitetsdanande faktorer bl.a. ekologiska förutsättningar och olika skötselåtgärder. En hög röjningsstyrka kan t.ex. resultera i en grövre diameter på grenar. Likaså har sen röjning inverkan på den grövsta grenens diameter, då den minskar. Det finns alltså en potential att erhålla god virkeskvalitet av tall i våra skogar. Detta är möjligt genom aktiv skötsel, att hålla täta förband, genom att gallra ut lågkvalitativa stammar och stamkvistning. Raka tallar ur vilka kan man utvinna ett högt sågutbyte är och kommer att vara en värdefull resurs i framtiden.In Sweden the quality of Scots pine (Pinus sylvestris) saw timber has decreased. It is especially due to increased labour cost that has led to rational and effective forest management. This study investigated the quality of Scots pine and the potential to produce high quality stems in 9 stands in Bergslagen, Sweden. Two different stand types were investigated: Pruned stands and conventional managed stands. The outcome was a high percentage of valuable stems in the pruned stands (72-94 %), and 46-56 % in the conventional managed stands. It is possible to produce high quality timber of Scots pine with active management, for example by pruning and careful selection of stems in thinnings.
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Sharp, Elizabeth P. "Watershed and Streamside Management Zone Characterization in the Allegheny Plateau of West Virginia." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/35071.
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The Streamside Management Zone (SMZ) is a cornerstone of forestry Best Management Practices to protect streamwater quality from non-point source pollution resulting from silvicultural operations. However, the exact width and harvest intensity of SMZs that best protects water quality while allowing for commercially valuable timber harvesting has not been determined. The long-term objective of this study is to characterize SMZs and watersheds before and after harvest with different SMZ widths and harvesting intensities in the Allegheny Plateau of West Virginia. The objective this paper is to present the pre-harvest SMZ and watershed characterization. Each of the watershed SMZs were characterized pre-harvest in terms of vegetation, water, soil, carbon, and monetary value within SMZs to predict how silvicultural treatments will affect the future stands. The major overstory tree species found are Acer saccharum, Liriodendron tulipifera, Fagus grandifolia, Tilia americana, Betula lenta, snags, Betula lutea, Fraxinus spp., and Acer rubrum. The overall average streamwater temperature is 13°C. Highest daily temperature occurred in the mid-afternoon and lowest temperatures occurred just before sunrise. Streamwater quality was good, with near neutral pH, low nitrogen content, and high dissolved oxygen. USLE erosion estimates predicted an erosion rate of 2.9 Mg/ha/yr in the SMZ. However, the sediment rods showed an overall accumulation of soil in the SMZ, averaging 173 Mg/ha/yr. This equates to an average watershed loss of 10.9 Mg/ha/yr. In-stream and SMZ LWD volume was approximately equal at 28 and 33 m3/ha. Large woody debris was more decayed in the SMZ than in-stream LWD.Master of Science
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Andersson, Helena W., and Anders Rickardson. "Timmerkvalitet hos björk i blandskog med gran." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-34444.
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Birch is the dominant deciduous tree species in Sweden but only 16 % is found in pure birch stands. The majority of the birch (51 %) is to be found in conifer dominated stands. Swedish forest land comprises approximately of 23 % mixed stands and one problem is that for mixed stands there are few management recommendations. The underlying aim of this thesis was to study the management of mixed forest stands of spruce and birch to achieve good timber quality of birch. The study was based on a literature study and measurement in a field experiment launched in 1998 by the Swedish University of Agricultural Sciences (SLU). This study indicates that it is possible to achieve good timber quality of birch in mixed stands of birch and spruce. However, it requires that birch in mixed stands with spruce should be managed similar to management programs of pure birch stands. Keywords: Birch, spruce, timber quality, mixed stands.
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Corrao, Jason James. "Relationships Between Streamside Management Zone Width and Biotic Communities of Headwater Streams in West Virginia." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/43919.
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The importance of streamside management zones (SMZ) in minimizing the impact of non-point source pollution from silvicultural operations is recognized by the forestry Best Management Practices of most states. However, research concerning the SMZ width and harvesting intensity required to maintain water quality and biotic communities is limited. The goal of this study is to evaluate the efficacy of different SMZ widths and forest harvesting intensities within SMZs, in maintaining the water quality and biotic communities of 22 headwater streams located in the mountains of East-central West Virginia. Streams were organized in four blocks and randomly assigned one of six silvicultural treatments involving variation of SMZ width and harvesting intensity within the SMZ; 30.5 m SMZ with no residual harvest, 30.5 m SMZ with 50% residual harvest, 15.3 m SMZ with no residual harvest, 15.3 m SMZ with a 50% residual harvest, 4.5 m SMZ and control (no harvest within the watershed). Stream water chemistry parameters (in particular, NO3, NH4, Ca, Mg, conductivity and total dissolved solids) as well as aquatic macroinvertebrate communities were monitored from June 2003 through March 2005. Average nitrate concentration in streams harvested with a 4.5 m SMZ was more than 4 times as high as that of control streams. Average summer and fall stream temperatures were inversely related to SMZ width. Mean values for a number of macroinvertebrate community metrics were indicative of poorer water quality in streams harvested with a 4.5 m SMZ. During this short-term study SMZs of at least 15.3 m appeared to be sufficient to maintain water quality. However, harvesting was restricted to one side of the stream and logging induced stream disturbances were observed even with SMZs of 30.5 m. For these reasons SMZs of at least 30.5 m are recommended as a cautionary measure to minimize the potential for impacts to biotic communities. In addition, residual harvest of up to 50% of the basal area within the SMZ did not appear to impact water quality during the temporal scope of the study.Master of Science
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Kim, Sei Jin. "Three Essays on the Implications of Environmental Policy on Nutrient Outputs in Agricultural Watersheds and the Heterogeneous Global Timber Model with Uncertainty Analysis." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1439601683.
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Heinze, Jason A. "Effects of Low-Input Vegetation Management on Pine-Hardwood Mixed Stands in the Northern Piedmont." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/33647.
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In an attempt to provide low-cost, low-input alternatives for regenerating pine-hardwood mixtures, this study examined several mechanisms that influence the growth of pine-hardwood stands. The Regeneration Alternatives Study is an ongoing experiment that was designed to gain biological and economical information concerning the growth and yield of loblolly pine and mixed hardwood species. Low-cost herbicide applications (stump treatment, basal stem spray, release, and soil spot release) were used to control competing vegetation during the study.
The four even-aged regeneration treatments applied to loblolly pine and mixed hardwood stands of this study had a significant effect on their growth. Loblolly pine growth increased and mixed hardwood growth decreased as the intensity of herbicide treatment increased for all age classes. In general, loblolly pine was more productive with more intense treatment applications on poorer sites following a growing season harvest. Hardwood species were more productive with less intense treatment applications on higher-quality sites following a dormant season harvest for all age classes. Loblolly pine planting following clearfelling, coupled with a herbicide stump and release treatment (treatment 4), resulted in the highest yields of loblolly pine, the greatest economic returns, and the greatest level of site utilization. However, treatment 4 also resulted in the lowest yield of mixed hardwoods and the lowest level of species richness. Loblolly pine planting following clearfelling, with (treatment 3) and without (treatment 2) a hardwood stump treatment application, resulted in a more even distribution of pines and hardwoods, depending on the treatment. Treatment 3 favored loblolly pine growth, especially following a growing season harvest on poor sites. Treatment 2 favored mixed hardwood growth, especially following a dormant season harvest on good sites. There were no differences between methods of release (basal spray or soil spot herbicide application). Economically, treatments 2 and 3 did not realize a profit on returns.
Pine yields, dbh, and basal area were all significantly greater following a summer season harvest as opposed to pine growth following a winter harvest with the same chemical treatments. The pine growth data indicated that less intense chemical treatments following a summer harvest can achieve the same or greater growth results than more intense chemical treatments following a winter harvest. The results of this study indicate a significant biological and economic tradeoff, depending on the level of hardwood control applied and the time of harvesting.Master of Science
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Chon, Song Hui. "Timbre Saliency, the attention-capturing quality of timbre." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119572.
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This dissertation proposes a new concept of timbre saliency as the attention-capturing quality of timbre and investigates its effects on the blending of concurrent notes and on the perceptual segregation of voices in counterpoint music. As this is the first effort to consider attentional factors in timbre perception research, a number of listening experiments were needed to define the concept and to establish the field. The first chapter introduces timbre saliency and connects it to other related research fields. A survey of visual saliency research was particularly helpful in developing experi- mental methodologies, because research in auditory saliency is still in its infancy.The second chapter describes two experiments to measure timbre saliency among the set of chosen timbres and discusses the importance of choosing the right experimental paradigm and how it can affect the outcome. This is especially relevant because saliency is a function of context, which is determined by the experimental setup. The measured saliency seems to be related to the fine structure in harmonic spectrum. These saliency relations became the basis for the following experiments. The next two chapters examine the effect of timbre saliency in a more realistic set- ting. First, the perception of blending is analyzed in concurrent unison dyads in terms of timbre saliency. The average blend ratings showed a negative correlation with timbre saliency, confirming the hypothesis that a highly salient timbre would not blend well with others, although the effect was not as strong as some other factors. Then the scope ex- pands to non-unison intervals in multiple voices in the fourth chapter, where the effect of timbre saliency on the voice recognition in short counterpoint excerpts is studied. The hypothesized systematic effect of timbre saliency was found in neither two- nor three-voice excerpts, although having a distinctive timbre on each voice helped the recognition of the middle voice in three-voice excerpts, which is the most difficult to listen to. The findings from the experiments, as well as a discussion on the general context effects, are summarized in the last chapter. This research extends traditional timbre research by considering the role of attention in sound and music perception. It provides a bridge between the perception of multi-voice music and auditory scene analysis, and hence has the potential to contribute to research in auditory perception as well as in music perception and cognition.Cette thèse propose un nouveau concept de saillance de timbre, conçu comme la qualité du timbre qui attire l'attention. Elle étudie les effets de saillance sur le mélange de notes simultanées et sur la séparation perceptive des voix dans la musique contrapuntique. Puisque c'est la première fois que les facteurs attentionnels sont pris en considération dans la recherche sur la perception du timbre, des expériences d'écoute ont été nécessaires pour définir le concept et établir le domaine de recherche autour de lui. Le premier chapitre introduit la saillance du timbre et la lie à d'autres domaines de recherche connexes. Une revue de la recherche sur la saillance visuelle aide particulièrement à développer les méthodes expérimentales car la recherche sur la saillance auditive est toujours dans son enfance. Le deuxième chapitre décrit deux expériences qui mesurent la saillance du timbre sur un ensemble de timbres sélectionnés et discute de l'importance de choisir le bon paradigme expérimental et de comment celui-ci pourra affecter le résultat. Cette approche est particulièrement pertinente puisque la saillance est fonction du contexte, qui est déterminé à son tour par la manipulation expérimentale. La saillance mesurée semble liée à la structure fine du spectre harmonique. Les relations de saillance établies deviennent la base pour les expériences ultérieures. Le deux chapitres suivants examinent l'effet de la saillance du timbre dans un contexte plus naturel. D'abord, la perception du mélange est analysée sur des dyades jouées à l'unisson en termes de la saillance des timbres. Les évaluations de mélange montrent une corrélation négative avec la saillance, confirmant l'hypothèse selon laquelle un timbre hautement saillant ne se mélangerait pas bien avec d'autres timbres, bien que cet effet n'était pas si important que d'autres facteurs. Ensuite, dans le quatrième chapitre les intervalles non unisson dans des voix multiples sont étudiés pour évaluer l'effet de la saillance du timbre sur la reconnaissance de voix dans de courts extraits de contrepoint. L'effet hypothétique de la saillance n'est retrouvé ni dans les extraits à deux voix ni dans ceux à trois voix. Ceci étant dit, la présence d'un timbre distinctif sur chaque voix aide la reconnaissance de la voix du milieu dans des extraits à trois voix, cette voix étant la plus difficile à entendre. Le dernier chapitre résume les résultats des expériences et présente une discussion des effets généraux de contexte. Cette recherche étend la recherche traditionnelle sur le timbre en prenant en considération le rôle de l'attention dans la perception du son et de la musique. Elle fournit un pont entre la perception de la musique à plusieurs voix et l'analyse de scènes auditives et contribuera potentiellement à la recherche sur la perception auditive, ainsi que sur la perception et la cognition musicales.
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Pupelis, Tomas. "Vėjavartų medienos kokybės vertinimas Dubravos eksperimentinėje mokomojoje miškų urėdijoje." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110601_115301-72321.
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Magistro darbe tiriama 2010 m. rugpjūčio mėnesį Dubravos EMMU audros pažeisti medynai ir juose pagaminta apvaliosios medienos kokybė.
Darbo objektas – 2010 m. rugpjūčio mėnesį škvalo Dubravos EMMU pažeisti medynai. Medienos kokybės bei medžių stiebų sortimentinės struktūros tyrimai atliekami Dubravos EMMU, Vaišvydavos girininkijoje esančiame škvalo pažeistame brandžiame eglyne.
Darbo tikslas – Įvertinti vėjavartų apimtį ir medienos kokybės pokyčius Dubravos EMMU.
Darbo metodai – Darbe naudoti dokumentų analizės, duomenų grupavimo, palyginimo, vidurkių skaičiavimo ir apibendrinimo metodai.
Darbo rezultatai. Išanalizavus Dubravos EMMU audros likvidavimo metu 2010 m. 10-12 mėn. pagamintų pjautinųjų sortimentų kiekius nustatėme, kad pagaminta 76% daugiau negu visada, prastesnės C klasės medienos. Dubravos EMMU, Šilėnų ir Vaišvydavos girininkijose įvertinus vėjo pažeidimus pagal plotą skirtingose augavietėse 60 brandžių medynų, nustatėme, kad intensyviausiai pažeisti medynai, kurie sudaro 35% yra Lcp augavietėse. Įvertinus pažeistus medynus pagal vyraujančią medžių rūšį nustatyta, kad didžiausią pažeistų medynų dalį 46.9% sudaro eglynai. Sortimentuojant 26 vėjo pažeistus medžius nustatyta, kad dėl pakitusios sortimentinės struktūros dėl lūžių taškuose suskeldėjusios medienos, prarandama iš viso 19.8% likvidinės medienos, bei vidutiniškai vieno medžio kirtimo atliekų kiekis padidėja 2.1 karto. Iš vėjo pažeistų medžių, pjautinųjų sortimentų medienos kokybė lyginant su galimai... [toliau žr. visą tekstą]Study object – 2010.08.08 storm damaged forest stand at Dubrava forest enterprise. Windblown timber quality assessment and storm damaged tree round wood structure assessment was done at Vaišvydava local forest district, at Dubrava forest enterprise. Study aim - to quantify most damaged forest types and to assess the round wood quality losses due to stem breakage and other defects which reduced merchantable timber volume during logging at damaged stands, after 2010.08.08 storm at Dubrava forest enterprise. Methodology – Data grouping, comparison, generalization, document’s analysis. Results - As the main changes in round wood quality during the period of salvage clear cuttings of storm damaged timber at Norway spruce stands at DFE were seen a significant increase of C quality class Norway spruce (Picea abies L) sawn logs – 76 per cent of all sawn logs. Evaluation of windthrow damage on DFE results showed that nearly half (46.9 percent) of all damages occurred on Norway spruce stands. As the most endangered forest soil type of spruce stands, where one third of all damages occurred, was recorded: fertile and humid Myrtillo-oxalidosum site. Survey of 26 storm damaged trees round wood structure showed, that 19.8% reduction of merchantable volume is due to breakage, and due to that fact was seen significant increase - 2.1 time amount of residuals. Windblown tree round wood quality assessment showed significant difference in timber quality if we compare it with normal conditions... [to full text]
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Salem, Thouraya. "Séchage intermittent du bois d’oeuvre : étude expérimentale et numérique." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0177/document.
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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 stratégiesTimber 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
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Hanson, Frank E. III. "Trumpet Timbre: A Comparative Investigation of the Tone Quality of Two Professional C Trumpets." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1391686077.
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Hanson, Frank E. "Trumpet timbre : a comparative investigation of the tone quality of two professional C trumpets /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487588249822482.
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Chudy, Magdalena. "Discriminating music performers by timbre : on the relation between instrumental gesture, tone quality and perception in classical cello performance." Thesis, Queen Mary, University of London, 2016. http://qmro.qmul.ac.uk/xmlui/handle/123456789/18378.
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Classical music performers use instruments to transform the symbolic notationof the score into sound which is ultimately perceived by a listener. For acoustic instruments, the timbre of the resulting sound is assumed to be strongly linked to the physical and acoustical properties of the instrument itself. However, rather little is known about how much influence the player has over the timbre of the sound - is it possible to discriminate music performers by timbre? This thesis explores player-dependent aspects of timbre, serving as an individual means of musical expression. With a research scope narrowed to analysis of solo cello recordings, the differences in tone quality of six performers who played the same musical excerpts on the same cello are investigated from three different perspectives: perceptual, acoustical and gestural. In order to understand how the physical actions that a performer exerts on an instrument affect spectro-temporal features of the sound produced, which then can be perceived as the player's unique tone quality, a series of experiments are conducted, starting with the creation of dedicated multi-modal cello recordings extended by performance gesture information (bowing control parameters). In the first study, selected tone samples of six cellists are perceptually evaluated across various musical contexts via timbre dissimilarity and verbal attribute ratings. The spectro-temporal analysis follows in the second experiment, with the aim to identify acoustic features which best describe varying timbral characteristics of the players. Finally, in the third study, individual combinationsof bowing controls are examined in search for bowing patterns which might characterise each cellist regardless of the music being performed. The results show that the different players can be discriminated perceptually, by timbre, and that this perceptual discrimination can be projected back through the acoustical and gestural domains. By extending current understanding of human-instrument dependencies for qualitative tone production, this research may have further applications in computer-aided musical training and performer-informed instrumental sound synthesis.
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Szymczak, Denise Andréia. "COMPACTAÇÃO DO SOLO CAUSADA PELOS TRATORES FLORESTAIS HARVESTER E FORWARDER NA COLHEITA DE Pinus taeda L." Universidade Federal de Santa Maria, 2013. http://repositorio.ufsm.br/handle/1/8710.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorSoil compaction has been becoming one of the main impacts caused by the activities of mechanized harvesting. The weight and movement of machines at the time of cutting and loading of timber combined with the not appropriate moisture condition of the soil are the main causes of soil structural degradation, observed mainly by changes in soil physical properties. Thus, this study aimed to identify soil compaction caused due to forest harvesting stages of Pinus taeda L. performed on three different soil moistures. A study in the city of Quedas do Iguaçu in southwestern Paraná was carried out in pine stands of Araupel S/A company. The research was assessed as completely randomized in and sub-subdivide plots with five replications. The eighteen treatments consisted of the interaction of three factors, namely: moisture (rainy day harvesting and 3 and 7 days after rain); harvesting operations (machine traffic (MT); no machine traffic (NMT) and timer landing (TL)); and time of collection (before and after harvest), being major plot, subdivided plots, and sub-subdivided plots in time, respectively. Soil under a native forest adjacent to the experiment was evaluated to infer on the changes caused to the soil regarding its cultivation and management. Results indicated that the difference in soil moisture represented by the different days of harvest after a rain did not influence differently the soil compaction. On the other hand, harvesting operations (MT, NMT and TL) impacted soil to a depth of 10 cm causing compaction on the traffic lines of the machines, while the eventual falling trees at the time of cutting and timber landing did not cause changes in density, macroporosity and resistance to penetration. The residual biomass from forest harvesting was essential to minimize soil compaction caused by machinery traffic that was close to the maximum. Comparison of physical parameters of soil under native forest and pine stand showed that planting and management of soils covered by natural forests alter the physical properties of the surface until 30 cm of depth.
A compactação vem se tornando um dos principais impactos causados ao solo pelas atividades de colheita florestal mecanizada. O peso e a movimentação das máquinas no momento do corte e extração da madeira, aliada à condição de umidade do solo imprópria para tal são as principais causas da degradação estrutural do solo, verificada principalmente por alterações em suas propriedades físicas. Nesse sentido, este trabalho objetivou identificar a compactação causada devido às etapas de colheita florestal de Pinus taeda L. realizada em três diferentes umidades do solo. O estudo foi realizado no município de Quedas do Iguaçu, em povoamento da empresa Araupel S/A. A pesquisa foi avaliada como delineamento inteiramente casualizado em parcelas sub-subdivididas, com dezoito tratamentos e cinco repetições. Os tratamentos foram compostos pela interação de três fatores, sendo eles: umidade (colheita em dia de chuva, três dias após a chuva e sete dias após a chuva), operações de colheita (com passagem de máquinas (CP), sem passagem de máquinas (SP) e estaleiro (E), e a ocasião de coleta (antes e depois da colheita), sendo respectivamente, parcela principal, parcelas subdivididas e parcelas sub-subdivididas no tempo. O solo sob uma floresta nativa adjacente ao experimento foi avaliado para inferir sobre as alterações provocados no solo pelo cultivo e manejo do mesmo. Os resultados obtidos indicam que a diferença de umidade no solo, representada pela colheita em diferentes números de dias após uma chuva, não influenciou de maneira diferenciada na compactação do solo. Por outro lado, as operações de colheita (CP, SP e E) impactaram o solo até a profundidade de 10 cm, causando a compactação nas linhas de tráfego das máquinas, enquanto que a eventual queda de árvores no momento do corte e o empilhamento de toras não provocaram alterações na densidade, macroporosidade e resistência a penetração. A biomassa residual da colheita florestal foi essencial para minimizar a compactação do solo causada pelo tráfego das máquinas que foi próxima da máxima. A comparação de parâmetros físicos do solo sob mata nativa e povoamento de pinus mostrou que o cultivo e manejo de solos que um dia foram cobertos por florestas naturais provoca alterações nas propriedades físicas do solo da superfície até 30 cm de profundidade.
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Reymore, Lindsey E. "Empirical approaches to timbre semantics as a foundation for musical analysis." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1586792450387823.
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Gazengel, Bruno. "CARACTERISATION OBJECTIVE DE LA QUALITE DE JUSTESSE, DE TIMBRE ET D'EMISSION DES INSTRUMENTS A VENT A ANCHE SIMPLE." Phd thesis, Université du Maine, 1994. http://tel.archives-ouvertes.fr/tel-00854901.
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Deux méthodes de caractérisation des qualités d' émission) des instruments de musique à anche validées. Ces méthodes consistent, d' une part à simuler les auto-oscillations résultant du couplage acoustiques (justesse, timbre, facilité simple sont développées et partiellement étudier le résonateur seul, d' autre part à entre le résonateur (supposé linéaire) et l' excitateur (non-linéarité supposée localisée à l' entrée du bec). Nous nous limitons à évaluer la fréquence fondamentale et le spectre de la pression interne au bec des instruments étudiés. Dans tout le document, nous supposons ces grandeurs représentatives de la justesse et du timbre. Pour la validation, nous comparons, pour des instruments réels, ces grandeurs aux grandeurs mesurées sur l' instrument en situation de jeu. Pour obtenir de telles conditions, nous avons réalisé une bouche artificielle, reproduisant l' embouchure du musicien avec stabilité et reproductibilité. Nous présentons une revue bibliographique et isolons un modèle physique élémentaire. Par analyse de ses solutions, on vérifie que la fréquence fondamentale de l' oscillation se déduit des fréquences de résonances au seuil linéaire grâce à un terme correctif. Celui-ci est la correction de longueur. Il est représentatif de l' embouchure et indépendant du doigté. Nous calculons les solutions discrètes du modèle à l' aide de l' impédance d' entrée mesurée ainsi que des paramètres équivalents à l' embouchure. La valeur de la fréquence d' échantillonnage est fixée par les caractéristiques de l' impédance d' entrée du résonateur. Ceci permet de minimiser les erreurs numériques de la fonction de réflexion "discrète". Les valeurs de la fréquence d' échantillonnage s' avèrent faibles vis à vis de la fréquence propre de l' anche. La transformation bilinéaire corrigée est choisie pour obtenir une anche "discrète" aux caractéristiques proches celles de l' anche "analogique". Les impédances d' entrées et les fréquences fondamentales de la pression dans le bec sont mesurées pour tous les doigtés des deux premiers registres de la clarinette et du saxophone alto. Les fréquences de résonance et les fréquences fondamentales sont comparées pour chacun des doigtés, une correction de longueur caractéristique de l' embouchure est estimée pour chaque registre. La comparaison des pressions simulées et mesurées dans le bec montre que la simulation permet de détecter les "notes difficiles" pour les doigtés de gorge de la clarinette. Cette détection est satisfaisante si on applique de faibles pressions d' alimentation au modèle. Le phénomène d' enroulement de l' anche sur la table du bec, omis dans le modèle physique, serait ici une des causes principales de ce désaccord. Une première approche théorique de ce phénomène est proposée à l' annexe A.
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Yorita, Ron. "Using Spectral Analysis to Evaluate Flute Tone Quality." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1308.
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Many skilled flutists place a high priority on "good" tone quality, or timbre. Timbre can be defined as the audible difference in character that a listener perceives for two notes played at the same pitch. Different timbres are determined by the combination and balance of harmonics that comprise a note. Unlike pitch and rhythm, timbre is difficult to objectively quantify. This project explores (1) how tone quality is described by skilled flutists, (2) whether the harmonic spectrum has some correlation with tone quality, (3) whether certain harmonic spectra are preferred, or considered "good".
Thirty-one flutists ranging from high school students to professionals were recorded. A set of samples was used in surveys and interviews to capture descriptors and ratings of tone quality. All of the recorded samples were analyzed using application programs, Harmonic Analysis Tools (HAT), created for this study. HAT uses digital signal processing techniques to produce "spectral signatures". The signatures consist of the harmonic content, pitch, and amplitude of a sample. In the future, with further development, HAT may be a useful tool for musicians for tone development in the practice room.
The outcome of this research is a baseline set of some often used descriptors. In addition, results showed some correlation between harmonic spectra and descriptors. There were also trends in preferences with respect to certain spectral characteristics. An unexpected finding was that University students showed divergent timbre preferences compared to highly experienced flutists.
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Palmblad, Simon. "A = 432: A superior tuning or just a different intonation? How tuning standards affects emotional response, timbre and sound quality in music." Thesis, Högskolan i Skövde, Institutionen för informationsteknologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-15414.
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The purpose of this study was to explore the ways tuning to A = 432 Hz affects emotional response, timbre, sound quality, character and tone compared to the standard tuning of A = 440 Hz, and whether or not it is humanly possible to discern a difference between these two. This was all done in an effort to evaluate claims that A = 432 Hz is superior to standard tuning in regards the previously mentioned factors. For this to be done, the history and development of tuning standards as well as intonation systems, presented alongside theories on the basic physics of sound, the effect of spectral manipulation on timbre and sound, and finally memory structures for remembering musical pitches. As a musician and composer, exploring new ways of creating emotion and controlling the effects of a composition, and dispelling potential misinformation is always a worthwhile pursuit. The study was performed by way of surveys where respondents were asked to listen to a composition in two versions, one in A = 440 Hz and the other in A = 432 Hz and then rate the perceived similarity between these two. They were then asked to give their answer regarding preference and associations of character and emotional response to each version. Results show that the claims of the A = 432 Hz proponents might not be as simple as portrayed, but rather a more complex series of relationships. There is support for the idea that the two tunings are unique enough for the average human to discern a difference between the two, and that some type of unique character is contained in each tuning.
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Harrison, Martin. "Time in quality constrained models." Thesis, University of Southampton, 1987. https://eprints.soton.ac.uk/361656/.
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Khakipoor, Banafsheh. "Applied Science for Water Quality Monitoring." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1595858677325397.
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Hyden, Eoin Andrew. "Operating system support for quality of service." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319971.
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Lévy, Vincent. "Survie ajustée sur la qualité de vie : développement d'un critère d'évaluation thérapeuthique dans les hémopathies lymphoi͏̈des malignes." Paris 6, 2001. http://www.theses.fr/2001PA066451.
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Kilungo, Aminata Peter. "Drinking Water Quality Monitoring." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/306073.
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This dissertation involves two different studies. The first concerns the real-time detection of microbial contamination in drinking water using intrinsic fluorescence of the microorganisms. The prototype, “Blinky”, uses LEDs that emit light at 365nm, 590nm, and 635nm for ultraviolet, amber, and red light, respectively. At 365 nm, the cellular components excited include reduced pyridine nucleotides (RPNs), flavins, and cytochromes to distinguish viable bacteria; at 590 nm, the cellular components excited include cytochromes for non-viable bacteria; at 635 nm, the cellular components excited include calcium dipicolinic acid (DPA) for spores. By using these three different wavelengths, the prototype can differentiate between viable and non-viable organisms and also has the potential to detect spores. The aim of this study was to improve the detection limit by modifying the design of the instrument and to establish the detection limit of viable and non-viable bacteria and spores. The instrument was modified by replacing existing LEDs with LEDs that had 50% more intensity. Two additional LEDs were added for amber and red light, bringing the total to four LEDs for each. The LEDs were also positioned closer to the photomultiplier tube so as to increase sensitivity. For UV, only two LEDs were used as previous. The detection limit of the viable bacteria was ~50 live bacteria/L. No change in the intrinsic fluorescence below the concentration of ~10⁸ dead bacteria/L was observed. The results for spore measurements suggested that most of the spores had germinated before or during the measurements and could not be detected. The instrument was successful in detection of viable bacteria and also differentiating viable and non-viable bacteria. The instrument was not successful in detection of spores. The second study was designed to assess the water quality of well construction in southeastern Tanzania. Three designs were tested: Msabi rope pump (lined borehole and covered), an open well converted into a closed well (uncovered well into a covered and lined well), and an open well (uncovered and may or may not be lined). The study looked at the microbial and chemical water quality, as well as turbidity. The survey included 97 water collection points, 94 wells and three rivers. For microbial analysis, heterotrophic plate count (HPC), total coliforms and E. coli tests were performed. Fifteen of these wells were further analyzed for microflora and diversity for wells comparison purposes, using culture methods, followed by polymerase chain reaction (PCR) and genome sequencing. Ten wells out of the fifteen were analyzed for calcium (water hardiness), potassium, nitrates, nitrites, chloride, fluoride, bromide, sulfate, iron, and arsenic. Two water collection points were also selected for organic compound analysis (gasoline components). All samples tested positive for coliforms. Two samples tested positive for Escherichia coli for the lined borehole (Msabi rope pump) and four samples from closed wells. All open wells tested positive for E. coli. There was more microbial diversity in open wells than the closed wells and Msabi rope pumps. Potential bacterial pathogens were detected in seven wells out of the fifteen examined. The wells that tested positive were one Msabi rope pump, one closed well; the rest were from open water sources. Open wells had high turbidity followed by closed wells. Msabi rope pumps had low turbidity comparing to the two wells designs. No traces of gasoline components were detected in any of the water sources. One well out of ten had high amounts of nitrates-nitrogen (> 10 mg/L). The results of this study showed that the Msabi rope pumps performed comparably to the closed wells in terms of microbial quality but performed better with regard to turbidity. The open wells performed poorly in terms of microbial water quality as well and turbidity. There was a statistical difference in HPC, total coliforms, E.coli numbers and turbidity between open wells, closed wells and the Msabi rope pumps. However, there was no statistical difference in HPC, total coliforms and E.coli numbers between the closed wells and Msabi rope pumps. Msabi rope pumps performed better in turbidity
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Yoo, Hyungsuk. "Quality of the Volterra transfer function estimation /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Rioux, Vincent. "Qualité sonore des tuyaux d'orgue à bouche : une étude interdisciplinaire sur l'harmonisation." Paris 6, 2001. http://www.theses.fr/2001PA066215.
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Tsang, Ho-on Frederick. "Time variable parameter estimation on the wind speed air quality model in Hong Kong /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B14723554.
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Hillhouse, Linden, and Ginette Blackhart. "Data Quality: Does Time of Semester Matter?" Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/84.
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When conducting scientific research, obtaining high-quality data is important. When collecting data from a college student participant pool, however, factors such as the time of the semester in which data are collected could cause validity issues, especially if the survey is completed in an online, non-laboratory setting. Near the end of the semester, students may experience more time pressures and constraints than at other times in the semester. These additional pressures may encourage participants to multi-task while completing the study, or to rush through the survey in order to receive credits as quickly as possible. The hypothesis of this study was that responses collected at the end of the semester would exhibit lower data quality than responses collected at the beginning of the semester. Data were collected online during the last two weeks of the fall 2018 semester (n = 312) and the first two weeks of the spring 2019 semester (n = 55). Participants were asked to write about an embarrassing situation and then completed a number of questionnaires assessing their thoughts and feelings about the event, personality traits, and participant engagement. Data quality was assessed using several different previously validated methods, including time spent on survey; the number of missed items; the number of incorrect embedded attention-check items (out of 12); the length of responses on two open-ended questions; self-reported diligence, interest, effort, attention, and whether their data should be used; and Cronbach’s alphas on the scales. Results showed that between the two groups, there were significant differences on length of open-ended responses, self-reported diligence, self-reported interest, effort, attention, neuroticism, and conscientiousness. Participants completing the study in the first two weeks of the spring 2019 semester had significantly longer open-ended responses and significantly higher levels of self-reported diligence, self-reported interest, effort, attention, neuroticism, and conscientiousness. Although there was not a significant difference in number of incorrect attention-check items between the two groups, it should be noted that only 46% of the total participants did not miss any check items. These results lend support to the hypothesis that data collected at the end of the semester may be of lower quality than data collected at the beginning of the semester. However, because the groups significantly differed on neuroticism and conscientiousness, we cannot determine whether the time of semester effect is a product of internal participant characteristics or external pressures. Nevertheless, researchers should take into account this end-of-semester data quality difference when deciding the time-frame of their data collection.
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Tran, Thai Tuan. "Contributions à la diffusion vidéo : de la fiabilité à l'équité en qualité." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0017/document.
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Cette thèse présente plusieurs contributions permettant d'améliorer la diffusion de vidéos. Dans la première partie de la thèse, nous évaluons et analysons les mécanismes de tolérance d'erreurs (correction et masquage d'erreurs). Les performances de ces différents mécanismes sont évaluées pour des taux de pertes de paquets variables. Les contributions suivantes mettent l'accent sur un code à effacements à la volée, appelée Tetrys, plus efficace que les codes en blocs classiques (Forward Error Correction - FEC). Tout d'abord, nous étudions l'application de Tetrys à la transmission vidéo temps réel par des chemins multiples. Nous proposons un découplage entre l'allocation de la charge et la gestion de la redondance pour Tetrys. Tetrys, lorsqu'il est couplé avec un mécanisme de répartition de charge appelé Encoded Multipath streaming (EMS), surpasse le couplage entre EMS et FEC pour les deux modèles de perte testés (Bernoulli et Gilbert-Elliott) en termes de taux de perte résiduel et de qualiée vidéo. En exploitant la capacité de correction de Tetrys, nous étudions ensuite les performances du décodage tardif où les paquets arrivant en retard sont décodés et utilisés pour stopper la propagation d'erreur. Enfin, une étude plus approfondie sur Tetrys propose un algorithme d'adaptation de la redondance, appelé A-Tetrys, permettant de gérer la dynamique du réseau. Cet algorithme combine des approches réactives et pro-actives pour adapter au mieux le taux de redondance. L'évaluation des performances montre que A-Tetrys parvient à gérer simultanément les variations du taux de perte, du modèle de perte et du délai. Nous étudions ensuite un autre challenge en proposant un nouveau critère d'équité : la qualité vidéo. Nous proposons un algorithme Q-AIMD qui permet un partage équitable de la bande passante en termes de qualité vidéo entre des ux concurrents. Nous présentons un système pour le déploiement de cet algorithme Q-AIMD et nous étudions sa convergence. L'évaluation de différentes métriques de qualité vidéo (PSNR, QP et VQM) montre une diminution importante des écarts de qualité vidéo entre plusieurs flux par rapport à l'approche traditionnelle AIMD qui se base sur le débit. De plus, une autre contribution sur ce sujet propose une nouvelle approche appelée courbe virtuelle. Contrairement à QAIMD qui est une approche décentralisée, la courbe virtuelle est une approche centralisée qui permet à la fois une équité entre les flux vidéo en termes de qualité vidéo et une équité entre les flux non-vidéo et flux vidéo en termes de débitThis thesis contributes to deal with the challenges in video delivery. In the first part of the thesis, we evaluate and analyse the error tolerance schemes (error protection and error resilience). The analysis shows how an error protection solution (equal and unequal) behaves in a wide range of packet loss rate from less lossy to error prone environments. We then study the performance of error protection schemes against the error resilience tools. Departing from the insights drawn from the evaluation and analysis, our next contributions focus on an on-the-y systematic erasure code, named Tetrys, which outperforms the traditional Forward Error Correction (FEC) approach. First, we study the application of Tetrys to real-time multipath transmission. We propose decoupling between load allocation and redundancy traffic for Tetrys. Tetrys coupled with a load splitting scheme, Encoded Multipath Streaming (EMS), outperforms the coupling between EMS and FEC for both loss patterns (Bernoulli and Gilbert-Elliott) in terms of residual loss rate and video quality. Exploiting the full reliable property of Tetrys, we then study the performance of Tetrys late-decoding (LD) where late-arrival packets are lately decoded and used to stop the error progatation. Finally, a deeper study on Tetrys focuses on an redundancy adaptation algorithm, named A-Tetrys, to cope with the network dynamics. We propose an algorithm which has both reaction and estimation behaviors to adapt its redundancy ratio. The performance evaluation shows that A-Tetrys copes well with the variations of both loss rate, loss pattern and delay. Then, we study another today challenge for a new fairness criterion, the video quality. We propose a Q-AIMD algorithm that enables a fair share in terms of video quality between competing ows. We discuss a system with the control granularity to deploy the Q-AIMD algorithm and study its convergence. The evaluation with different video quality metrics (PSNR, QP and VQM) shows an important diminution in video quality discrepancies between different transmitted ows compared to traditional throughput-based AIMD. Looking from another view, another work focuses on a virtual curve approach. Unlike Q-AIMD which is a decentralized approach, virtual curve is a centralized approach that enables both intra-fairness between video ows in terms of video quality and inter-fairness between non-video and video ows in terms of throughput
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Zachrisson, Mikael. "High Quality Shadows for Real-time Surface Visualization." Thesis, Linköpings universitet, Medie- och Informationsteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-133214.
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This thesis describes the implementation of a shadowing system able to produce hard shadows. Shadow mapping is the most common real-time shadowing algorithm but it suffers from severe aliasing artifacts and self-shadowing effects. Different advanced techniques based on Shadow Mapping are implemented in this thesis with the objective of creating accurate hard shadows. First, an implementation based on Cascaded Shadow Maps is presented. This technique improves the visual quality of shadow mapping by using multiple smaller shadow maps instead of a large one. The technique addresses the fact that objects near the viewer require a higher shadow map resolution than objects far away. The second technique presented is Sub-pixel Shadow Mapping. By storing information about occluding triangles in the shadow map this technique is able to produce accurate hard shadows with sub-pixel precision. Both methods can be combined in order to improve the resulting shadow quality. Finally, a collection of advanced biasing techniques that minimize the self-hadowing artifacts generated by shadow mapping are presented. The final implementation achieves real-time performances with considerably improved quality compared to standard shadow mapping.
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Yimga, Jules O. "Essays on product quality in commercial aviation." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32544.
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Doctor of PhilosophyEconomics
Philip G. Gayle
This dissertation consists of three essays on product quality in commercial aviation. Since the mid-1990s, major airlines that serve the U.S. domestic market have increasingly found it appealing to form alliances. Amidst the recent emergence of airline alliance formation, this dissertation has sought to answer questions on the product quality implications of policies regarding cooperation among airlines in the U.S. domestic air travel industry. A challenge that empirical work faces in studying the relationship between airline alliances and product quality is to find reasonable measure(s) of product quality. The first essay sheds light on whether the route network integration that comes with an airline alliance provides sufficient extra incentive to partner carriers to improve their flight routing quality. Evidence suggests that routing quality for Delta/Continental/Northwest's--our alliance of interest--products decreases in markets where pre-alliance competition among alliance partners exists, resulting in substantial negative welfare effects for passengers. In fact, routing quality for Delta/Continental/Northwest products decreased by 0.256% below the mean routing quality of the entire sample's products. More interestingly, the codeshare effects in specific markets where the alliance firms competed prior to the alliance, are also negatively associated with routing quality of the alliance firms' products, resulting in a fall in consumer utility of $0.5 per consumer. The second essay explores the potential relationship between on-time performance and airline code-sharing. Although flight delay has always received much attention, we are unaware of any empirical research that measures the on-time performance effects of airline alliances. We empirically investigate the on-time performance effects of the largest U.S. domestic alliance that began in June 2003--an alliance between Delta Air Lines, Northwest Airlines and Continental Airlines. We find evidence that code-sharing improves alliance partners' on-time performance and that the size of the alliance effect on on-time performance depends on pre-alliance competition in a market, with the effect being larger in markets where the partners competed in prior to the alliance. Using a structural econometric model, the third essay attempts to provide an alternative explanation to a long-standing question: why are airlines late? Airlines usually claim that air travel delays are out of their control, placing the blame on adverse weather or air traffic control as the most common reasons. Despite these claims, data on causes of flight delay reveal that the share of delay caused by weather and air traffic control has been on the decline while the share of delay caused by airlines has been on the rise. This suggests that on-time performance improvement is well within the reach of carriers. We investigate why airlines have little or no incentive to improve on-time performance. We also measure the cost of delay borne by consumers in terms of how much monetary value they are willing to pay to avoid delay. We find that consumers are willing to pay $0.78 for every minute of arrival delay which after extrapolation, amounts to consumer welfare effects of $1.76 billion. Our findings suggest that airlines have little to no incentive because their markups do not increase when they improve on-time performance. In fact, the marginal increase in price resulting from on-time performance improvement is offset by an increase in marginal cost causing a zero net effect on markup.
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Fiorentino, Laura A. "Using Lagrangian Coherent Structures to Study Coastal Water Quality." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_theses/267.
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In order to understand water quality in the coastal ocean and its effects on human health, the necessity arises to locate the sources of contaminants and track their transport throughout the ocean. Dynamical systems methods are applied to the study of transport of enterococci as an indicator of microbial concentration in the vicinity of Hobie Beach, an urban, subtropical beach in Miami, FL that is used for recreation and bathing on a daily basis. Previous studies on water quality have shown that Hobie Beach has high microbial levels despite having no known point source. To investigate the cause of these high microbial levels, a combination of measured surface drifter trajectories and numerically simulated flows in the vicinity of Hobie Beach is used. The numerically simulated flows are used to identify Lagrangian Coherent Structures (LCSs), which provide a template for transport in the study area. Surface drifter trajectories are shown to be consistent with the simulated flows and the LCS structure. LCSs are then used to explain the persistent water contamination and unusually high concentrations of microbes in the water off of this beach as compared with its neighboring beaches. From the drifter simulations, as well as field experiments, one can see that passive tracers are trapped in the area along the coastline by LCS. The Lagrangian circulation of Hobie Beach, influenced primarily by tide and land geometry causes a high retention rate of water near the shore, and can be used to explain the elevated levels of enterococci in the water.
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Stjärndahl, Rickard, and Tobias Aronsson. "Problemanalys vid Aros Quality Group Enclosure Systems AB." Thesis, Jönköping University, JTH, Industrial Engineering and Management, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-501.
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The aim of this report is to increase the knowledge and understanding of the problems within the production at AQ Enclosure systems, and thereby achieve a more stable flow throughout the whole process, a better working environment and better competition advantages. The internal flow along with the external cooperation is very important for the company, because it views flexibility and short leadtime as it is the most important competitive means. The part of AQ production that’s been investigated is the manufacturing of ATM-machines, where the costumer is Banqit. This company is a rater small company with about 4 % of the world market of ATM-machines.
In order to achieve the aim of the report extensive interviews have been carried out with employees at AQ. Employees in both the administrative part as well as the manufacturing part has been interviewed. The interviews have been conducted in a way were the respondents have had the opportunity to study the questions in advance.
The survey has given a result which indicates problem over a wide scale. A lot of the company problems do not lie in a particular department; they rather include the whole company. The picture of their problems became more complex whereas different respondents look at the same problems in different ways. One big difference in views was clearly identified between office staff and the producing staff. The problems that emerged were not related to lack of machine capability, the problems were rather linked to the managing of production and organization. One example of this problem is the producing personnel’s lack of knowledge and commitment to the company philosophy. The problems concerning management also reflect in a rather strong feeling that divides the company in two, us and them. This feeling affects the whole production line. The producing personnel feels that the office lack understanding of their everyday work and don’t encourage suggestions concerning process evolvement. One other big problem concerning AQ’s production is that some of their key suppliers are either single source or locked from their costumer Banqit.
The conclusions of the report shows several areas in which AQ can improve. One measure that the company can implement is introducing a more foreseeable and visual handling of their pallets within the factory. The company management ought to find ways to better mediate the production philosophy throughout the entire organization. Furthermore, the company management should increase the will to see potential ways of improving and increase the inclination of expressing those suggestions. The suggestions should not only concern the personnel’s own workplace but rather span over the entire process. The report also identifies possible areas of improvement concerning the internal and external team cooperation. The different teams ought to see each other as costumers and produce an equally good result regardless of if the item is produced for an internal department or an external costumer.
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Ramaraj, Sharath. "Supporting Quality of Service in Distributed Virtual Environments." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/35401.
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We present a resource allocation perspective to Quality of Service in Distributed Virtual
Environments. The user of a DVE system will have improved Quality of Service if he/she
is allocated the right amount of resources at the right time. Instead of allocating resources
on a static basis, we adopt a dynamic need based resource allocation scheme that provides real-time resource allocation. Optimal resource assignments are calculated o2ine and a neural network is trained with the knowledge of optimal solutions from the o2ine Operations Research Techniques and it is then used to deliver near-optimal resource allocation decisions in real-time. We also present a case study of network bandwidth allocation and prove the usefulness of the technique.Master of Science
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Tang, Dikai Nate. "MARS Spectral CT: Image quality performance parameters using the Medipix3.0 detector." Thesis, University of Canterbury. Department of Physics and Astronomy, 2013. http://hdl.handle.net/10092/7828.
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The research in this thesis was undertaken because information on the relationship between scan parameters and image quality for the MARS spectral CT was lacking. However, the MARS spectral CT is expected to extend into clinical use in the future, so it is absolutely crucial that we know how the quality of the images that it produces is effected by different can parameters. This will allow us to make further improvements to the machine, and ultimately help clinicians to visualise important information in patients which are not revealed by other imaging modalities. This thesis provides information on how the image quality is affected by different scan parameters on the MARS spectral CT using a Medipix3 silicon quad detector. In particular, it explores how different numbers of projections,
exposure time products (mAs), and peak tube voltages (kVp) with different threshold energies (kV) effect the image noise, image resolution and image uniformity, respectively. This provides a set of guidelines for future work using the MARS scanner to obtain images of optimal quality. This thesis
also determines that the new image reconstruction software mART developed by Niels de Ruiter, is a suitable replacement for the reconstruction software OctopusCT that is currently being used by the MARS team. Using mART reduces the scan times and dose delivered by the MARS spectral CT.