Dissertations / Theses on the topic 'Timber degradation'
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Martin, W. "Recovery of impregnated gold from waste mine timber through biological degradation." Thesis, Cape Technikon, 2000. http://hdl.handle.net/20.500.11838/2156.
Full textThe large quantities of wood chips produced at mines from damaged underground timber contain gold that cannot be completely recovered by cyanidation. A fungus that can degrade a portion of the wood matrix will allow the gold that was previously locked up, to come into contact with the cyanide solution during beneficiation, thereby improving recoveries. The fungus Phanerochaete chrysosporium produces enzymes that use the organic compounds found in lignin as substrate. Consequently, the fungus is able to selectively break down lignin, which is one of the major components of wood. Chips sampled from Vaal Reef Mine contained between 2 and 5 mg/kg gold. The main source of gold in the chips was determined to be impregnated gold-bearing ore and discrete gold particles. Direct cyanidation resulted in around 60 per cent recovery prior to biological treatment. Despite relatively high weight losses caused to the chips as a result of treatment with Phanerochaete chrysosporium gold recovery only increased 10 per cent after 4 weeks treatment compared to direct recovery without treatment.
McGeachie, M. T., University of Western Sydney, College of Law and Business, and of Construction Property and Planning School. "Characterisation of the Sydney region in relation to corrosion, timber decay risk factors and the corrosion of nails in timber in covered conditions." THESIS_CLAB_CPP_McGeachie_M.xml, 2001. http://handle.uws.edu.au:8081/1959.7/491.
Full textDoctor of Philosophy (PhD)
Jantan, Mohd Dahlan. "Chemical preservation of some refractory timber species of Malaysia." Thesis, University of Portsmouth, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310381.
Full textChristin, Jérôme. "Système de fondation sur pieux bois : une technique millénaire pour demain." Thesis, Paris Est, 2013. http://www.theses.fr/2013PEST1105/document.
Full textMany buildings and bridges built on timber pile foundations still stand in France. The bridges on rivers “Loire” and “Seine”, the castle of Chambord, the “Grand Palais” in Paris are a few examples of French monuments founded on timber piles. However, despite a large number of buildings and bridges constructed in France, the feedback on the residual bearing capacity and the degradation of timber piles is scarce. The main objectives of this work, which is part of the “Pieux Bois” national research project, are, on the one hand, to define a methodology in order to analyze timber pile foundations degradation, and on the other hand, to propose a design method of timber piles based on the results obtained from pressuremeter tests. The state of the art made in the national project identified about one hundred French bridges built on timber piles between the Middle Ages and the industrial era. They are mainly located in basins of rivers. Pathologies were observed on bridges and reinforcement solutions were implemented in order to avoid any future problems. The methodology for the inspection of timber pile foundations given in the Dutch guide was applied to investigate the degradation of timber piles under an existing railway bridge near Bordeaux. Series of laboratory tests were carried out on soil (silt) and wood with a direct shear box. The mechanical properties of the interface were studied. Shear tests between mortar, steel and silt were also carried out. The influence of material roughness and silt moisture content on the shear strength properties of the interface was examined. In addition, timber piles were driven and loaded on two experimental sites. The timber piles were instrumented with removable extensometers. The results of these load tests were included in a database which contained timber piles loading test results published in literature. The approach adopted to establish the design method of deep foundation based on the results obtained from pressuremeter tests described in the new national standard for application of Eurocode 7 was modified. A new model of calculation of timber piles shaft and base resistance driven in clay silt and sand gravels was determined with statistical studies from this database
Simson, Scott Andrew. "Development of a model for railway track maintenance planning." Thesis, Queensland University of Technology, 1999. https://eprints.qut.edu.au/36116/1/36116_Simson_1999.pdf.
Full textLu, Jin 1959. "Degradation processes and related reliability models." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39952.
Full textThe degradation process is assumed to follow a Wiener process. Failure is defined as the first passage of this process to a fixed barrier. The degradation data of a surviving item are described by a truncated Wiener process and lifetimes follow an inverse Gaussian distribution. Models are developed for three types of data structures that are often encountered in reliability studies, terminal point data (a combination of degradation and lifetime data) and mixed data (an extended case of terminal point data); conditional degradation data; and covariate data.
Maximum likelihood estimators (MLEs) are derived for the parameters of each model. Inferences about the parameters are based on asymptotic properties of the MLEs and on the likelihood ratio method. An analysis of deviance is presented and approximate pivotal quantities are derived for the drift and variance parameters. Predictive density functions for the lifetime and the future degradation level of either a surviving item or a new item are obtained using empirical Bayes methods. Case examples are given to illustrate the applications of the models.
Addai, Obeng A. "Regulated Feedback Networks with Degradation." Youngstown State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1444046732.
Full textDaheur, Jawad. "Le Parc à bois de l'Allemagne : course aux ressources et hégémonie commerciale dans les bassins de la Vistule et de la Warta (1840-1914)." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAG041.
Full textThis thesis deals with the German attempts to take control over timber resources in the Baltic area between 1840 and 1914. Focused on the trade in the Vistula and Warta river basins, it shows how the rising German economy managed to make the local forests into its backyard by securing cheap and stable access to timber resources. German firms progressively achieved trade dominance by developing transport technologies and reinforcing their financial and organizational capacities. They also managed to take advantage of the local economic and political weaknesses. Through ecological and economic explanation of timber extraction and processing, the thesis underlines the role played by foreign timber in the preservation of the German forests. It also describes the impact of this process on the local population and environment. Finally, the thesis advocates for a truly global history of the German forest
Watson, William H. "DNA Degradation as an Indicator of Post-Mortem Interval." Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc30523/.
Full textOlsen, Peter A. "Shear Modulus Degradation of Liquefying Sand: Quantification and Modeling." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/1214.
Full textWilliams, John Burgess. "Prediction of Post Mortem Interval from Degradation of Endogenous Nucleotides in Human Subjects." Thesis, University of North Texas, 1993. https://digital.library.unt.edu/ark:/67531/metadc277773/.
Full textShahabi, Sagedeh Sadat. "Non-invasive Monitoring of Degradation of Poly (lactide-co-glycolide) Hollow Fiber Channel for Recovery of Spinal Cord Injury Using Magnetic Resonance Imaging." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23566.
Full textHumbert, Lorraine L. "A Preliminary Study for Estimating Postmortem Interval of Fabric Degradation in Central Florida." Honors in the Major Thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1599.
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Bachelors
Sciences
Anthropology
Lundbäck, Marie. "Longterm performance of polyolefins in different environments including chlorinated water: antioxidant consumption and migration and polymer degradation." Doctoral thesis, KTH, Fiber- och polymerteknik, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-238.
Full textQC 20101020
Deng, Yingjun. "Degradation modeling based on a time-dependent Ornstein-Uhlenbeck process and prognosis of system failures." Thesis, Troyes, 2015. http://www.theses.fr/2015TROY0004/document.
Full textThis thesis is dedicated to describe, predict and prevent system failures. It consists of four issues: i) stochastic degradation modeling, ii) prognosis of system failures, iii) failure level estimation and iv) maintenance optimization. The time-dependent Ornstein-Uhlenbeck (OU) process is introduced for degradation modeling. The time-dependent OU process is interesting from its statistical properties on controllable mean, variance and correlation. Based on such a process, the first passage time is considered as the system failure time to a pre-set failure level. Different methods are then proposed for the prognosis of system failures, which can be classified into three categories: analytical approximations, numerical algorithms and Monte-Carlo simulation methods. Moreover, the failure level is estimated from the lifetime distribution by solving inverse first passage problems. This is to make up the potential gap between failure and degradation records to reinforce the prognosis process via first passage problems. From the prognosis of system failures, the maintenance optimization for a continuously monitored system is performed. By introducing first passage problems, the arrangement of preventive maintenance is simplified. The maintenance decision rule is based on a virtual failure level, which is solution of an optimization problem for proposed objective functions
Wu, Xinying. "Reliability Assessment of a Continuous-state Fuel Cell Stack System with Multiple Degrading Components." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1556794664723115.
Full textGebrehiwot, Worku Zewdie. "Climate, land use and vegetation trends." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-209668.
Full textSmith, Austin Gregory. "Characterization and Quantification of Early Stages for Organic Coatings Applied on AA2024/AA7075 by Correlating Frequency Domain Approach in Real Time." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1399125698.
Full textAlling, Vanja. "Terrestrial organic carbon dynamics in Arctic coastal areas : budgets and multiple stable isotope approaches." Doctoral thesis, Stockholms universitet, Institutionen för tillämpad miljövetenskap (ITM), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-43455.
Full textAt the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: In press. Paper 2: Submitted. Paper 4: Manuscript.
Arantes, Arielle Elias. "Caracterização biofísica e potencial à intensificação sustentável da pecuária brasileira em pastagens." Universidade Federal de Goiás, 2017. http://repositorio.bc.ufg.br/tede/handle/tede/8075.
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Cattle ranching is the main land use activity in Brazil, with about 175 million hectares of cultivated pasture, with at least 50% of these being with some degree of degradation. Degraded pastures present low biomass production of little nutritional value, which leads to low animal weight gain in the rainy season and loss of weight in the dry season. Due to its low productive efficiency, if these areas were identified and recovered, they could be intensified, freeing pasture areas for other uses. In this context, the objective of this work was to evaluate the pasture vigor and the potential livestock intensification for Brazil. In order to obtain the vigor and productivity of Brazilian pastures, a Pasture Strength Index (PVI) was generated by integrating the α (intercept) and β (slope) coefficients, derived from the linear regression of the vegetation index (NDVI) over time (2000 to 2017). Pastures with low PVI values were located throughout the Caatinga biome, in the MATOPIBA region of the Cerrado biome, in the eastern portion of Mato Grosso do Sul, southeastern of Mato Grosso and northwestern of Goiás. These areas are associated to regions of higher water deficit, as shown by the relationship between the PVI and the total annual precipitation (R² = 0.40) and evapotranspiration. For the Cerrado biome, the PVI showed high spatial correspondence with the green biomass and percent green cover. Green biomass and percent green cover were generated from extrapolation of field data to the spatial resolution of MODIS images. The areas with lower PVI values in the Cerrado biome also had lower green biomass (< 6000 kg ha-1 ) and percent green cover (< 47%) during the growing season. Considering the accumulated green biomass in the growing season, it was observed that the Cerrado’s cattle stocking rate could increase from 1.11 AU ha-1 (real cattle stocking rate) to 2.56 AU ha-1 (potential cattle stocking rate). The real cattle stocking rate in 2015 was generated through the integration of the 2006 Livestock Census data with the Livestock Production data for the year 2015. The potential cattle stocking rate was obtained from the relationship between the forage production (green biomass and gross primary productivity - GPP) and the forage demand of one animal unit (1 AU = 450 kg). The potential of intensification was determined from the difference between the actual and the potential cattle stocking rates. For all of Brazil, the cattle stocking rate in 2015 was 0.97 AU ha-1 , reaching a potential of 3.60 AU ha-1 , that is, the potential for intensification was 2.63 AU ha-1 . The greatest potential of intensification occurred in the South region (3.62 AU ha-1 ), and the lowest in the North (2.13 AU ha-1 ) and Northeast (2.22 AU ha-1 ) regions of Brazil.
A pecuária é a principal atividade de uso da terra no Brasil, com cerca de 175 milhões de hectares de pastagens cultivadas, sendo que pelo menos 50% destas estão com algum nível de degradação. Pastagens degradadas apresentam baixa produção de biomassa de pouco valor nutritivo, o que leva a um menor ganho de peso animal na estação chuvosa e a perda de peso na estação seca. Pela sua baixa eficiência produtiva, caso haja a identificação e a recuperação destas áreas, estas poderiam ser intensificadas, liberando áreas para outros usos. Neste contexto, este trabalho teve por objetivo avaliar o vigor e o potencial de intensificação das pastagens brasileiras. Para obter o vigor das pastagens, gerou-se um Índice de Vigor do Pasto (PVI), por meio da integração dos coeficientes α (intercepto) e β (slope), obtidos da regressão linear do índice de vegetação (NDVI) ao longo do tempo (2000 a 2017). As pastagens com os menores valores de PVI localizaram-se em todo o bioma Caatinga, na região do MATOPIBA no bioma Cerrado, no leste do Mato Grosso do Sul, sudeste do Mato Grosso e noroeste de Goiás. Estas áreas estão associadas a regiões de maior déficit hídrico, como mostrado pela relação do PVI com a precipitação (R² = 0,40) e a evapotranspiração acumuladas durante o ano (R² = 0,30). Para o bioma Cerrado, o PVI apresentou alta correspondência espacial com a biomassa verde e com o percentual de cobertura verde. A biomassa verde e o percentual de cobertura verde foram geradas a partir da extrapolação de dados de campo para a resolução espacial das imagens MODIS. As áreas com menores valores de PVI no bioma Cerrado também tiveram pouca biomassa verde (< 6.000 kg ha-1 ) e porcentagem cobertura verde (< 47%) durante a estação de crescimento. Considerando o acúmulo de biomassa verde na estação de crescimento, percebeu-se que a lotação bovina do Cerrado poderia aumentar de 1,11 UA ha-1 (lotação real) para 2,56 UA ha-1 (lotação potencial). A lotação bovina real em 2015 foi estimada por meio da integração de dados do Censo Agropecuário de 2006 com dados da Produção Pecuária Municipal de 2015. Já a lotação potencial, foi obtida a partir da relação entre a produção de forragem (biomassa verde ou produtividade primária bruta – GPP) e a demanda de forragem de uma unidade animal (1 UA = 450 kg). A partir da diferença entre a lotação bovina real e potencial determinou-se o potencial de intensificação. Para todo o Brasil, a lotação bovina em 2015 foi de 0,97 UA ha-1 , podendo chegar a um potencial de 3,60 UA ha-1 , ou seja, o potencial de intensificação foi de 2,63 UA ha-1 . O maior potencial de intensificação se deu na região Sul (3,62 UA ha-1 ) e os menores nas regiões Norte (2,13 UA ha-1 ) e Nordeste (2,22 UA ha-1 ) do Brasil.
Vernaez, Oscar. "Evaluation of an oil-based self-degradable gel for oil production applications." Thesis, Pau, 2015. http://www.theses.fr/2015PAUU3020/document.
Full textIn this work, a solution of peroxide crosslinked styrene-butadiene rubber (SBR) has been transformed to a self-degradable gel system by adding hydroperoxide as a degradation agent to the formulation. Dynamic rheometry was employed to calculate the relaxation time with a new method presented along with a full review of methods for calculation of the relaxation time spectrum from oscillatory rheometry. In-situ and ex-situ experiments were performed to evaluate the evolution of crosslinking and degradation reactions. Structural changes in the polymer network were visible within the relaxation time spectra. The degradation kinetics of styrene butadiene rubber (SBR) in solution was studied in anaerobic conditions and the characterization was performed by multiangle light scattering coupled to size exclusion chromatography (SEC-MALS). Using population balance equations, it was possible to calculate the kinetic constants for thermal and thermooxidative degradation. Different formulations of these oil-based self-degradable gels have been evaluated as possible diverting agents during oil wells operations. The time dependent rheological behavior of the gels was measured to verify polymer crosslinking, maximum gel strength and gel degradation, all of which can be adjusted by varying formulation depending on operation needs. Single core tests were performed to evaluate pressure resistance as a function of gel strength and gel degradation. Parallel cores tests were also carried out to validate diversion efficiency and mobility restoration
Jia, Ning. "Conception conjointe optimisée de lois de contrôle et d'ordonnancement." Phd thesis, Institut National Polytechnique de Lorraine - INPL, 2009. http://tel.archives-ouvertes.fr/tel-00369354.
Full textmodèle (m,k)-firm. Plus particulièrement, nous avons étudié l'impact de distribution de rejets sur la QdC d'une boucle de contrôle et, sur la base des résultats obtenus, nous avons spécifié une méthode de co-conception permettant de déterminer les paramètres (gain) optimaux de la loi de contrôle et les paramètres de la contrainte (m,k)-firm spécifiant le rejet sélectif d'instances. Cette proposition a été validée sur modèles à l'aide de techniques analytiques, par simulation ainsi que grâce à des expérimentations. Notre deuxième objectif est d'étudier le problème de l'ordonnancement d'un ensemble de tâches temps réel réalisant chacune les algorithmes de contrôle dans une application centralisée évolutive. Nous proposons un mécanisme d'ordonnancement qui ajuste en ligne les contraintes
(m,k)-firm des tâches suivant la configuration courante de l'application de manière à ce qu'un critère reflétant la performance globale de l'application soit optimal à tout instant.
Hasan, Ali Fadhil. "Évaluation de la dégradation des forêts primaires par télédétection dans un espace de front pionnier consolidé d’Amazonie orientale (Paragominas)." Thesis, Le Mans, 2019. http://www.theses.fr/2019LEMA3002/document.
Full textThe forest degradation is a change of the structure and the composition of flora and fauna, which leads to a loss of biodiversity, of production of goods and services and an increased vulnerability to weather hazards and fires. This process concerns large areas in the tropics, particularly in agricultural frontier where primary forest is subject to timber extraction, fire and fragmentation. Remote sensing is used to assess the magnitude and the extent of forest degradation. However, the methodologies available are still insufficient. The scientific challenge is to develop methods adapted to large areas to analyze the effect of different disturbances on the trajectories followed by the forest cover. It is also to identify different intensities of degradation following disturbances events. This is a prerequisite for defining and implementing appropriate management plans. The first axis of this work aims to map annually the extent of the disturbances, to identify the main types of disturbances and to characterize the restoration trajectory of the photosynthetic activity. This work is based on time series of Landsat images processed using CLASlite software. The aggregation of the annual coverages resulting from treatments with CLASlite also made it possible to constitute an indicator of degradation resulting from the accumulation of disturbance processes over several years. The second axis aims to evaluate the evolution of the forest sensitivity to drought as a function of its degradation and to build a degradation indicator. The approach uses MODIS images and TRMM precipitation data. This work is implemented in the municipality of Paragominas (state of Pará, Brazil)
Krause, Jakob. "Kontextsensitive Prognoseverfahren für das Abnutzungsverhalten von technischen Systemen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-130908.
Full textTechnical systems are prone to deterioration. This leads to negative consequences like break-downs. Maintenance actions are executed in order to transfer technical systems back into healthy states. If break downs occur suddenly, the consequences can be dramatic. Therefore, it is reasonable to schedule maintenance actions based on health-state predictions. Thereby, health state predictions are impeded by the fact that technical systems often deteriorate variably, depending on certain stress factors. Furthermore, the effects of variable deterioration behavior can be hidden by system specific behavior. Thus, approaches are shown which integrate variable deterioration behavior into healthstate predictions while influences caused by the system specific behavior are considered. Consequently, maintenance actions can be scheduled more efficiently which spares resources and reduces costs
Latappy, Hubert. "Étude des COV issus de la dégradation thermique et oxydative des matériaux polymères." Phd thesis, Université Paris Sud - Paris XI, 2014. http://tel.archives-ouvertes.fr/tel-01059771.
Full textSantini, Thomas. "Contribution à l'étude de la fiabilité des MOSFETs en carbure de silicium." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI021/document.
Full textRecent years have seen SiC MOSFET reach the industrial market. This type of device is particularly adapted to the design of power electronics equipment with high efficiency and high reliability capable to operate in high ambient temperature. Nevertheless the question of the SiC MOSFET reliability has to be addressed prior to considering the implementation of such devices in an aeronautic application. The failure mechanisms linked to the gate oxide of the SiC MOSFET have for a long time prevented the introduction of the device. In this manuscript we propose to study the reliability of the first generation of SiC MOSFET. First, the mechanism known as the Time–Dependent Dielectric Breakdown is studied through experimental results extracted from literature. Our study shows the successful application of a Weibull law to model the time-to-failure distribution extracted from the accelerated tests. The results show also a significant improvement of the SiC MOSFET structure with respect to this phenomenon. In a second step, the impact of the threshold voltage instability is quantified through accelerated tests known as High Temperature Gate Bias. The collected degradation data are modeled using a non-homogeneous Gamma process. This approach allows taking into account the variability between devices tested under the same conditions. Acceleration factors have been proposed with respect to temperature and gate voltage. Eventually the study delivers a primary estimation of the remaining useful lifetime of the SiC MOSFET in a typical aeronautic application
Propastin, Pavel. "Remote sensing based study on vegetation dynamics in drylands of Kazakhstan." Doctoral thesis, Stuttgart Ibidem-Verl, 2007. http://hdl.handle.net/11858/00-1735-0000-0006-B26A-A.
Full textVerma, Atul. "Transients in Polymer Electrolyte Membrane (PEM) Fuel Cells." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/64247.
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Al, jed Habib. "Influence de la recharge rapide sur les performances des accumulateurs lithium des véhicules électriques dans le cadre de l'utilisation postale." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0290/document.
Full textThis thesis aims to study the influence of fast charging on the aging of lithium batteries, and its impact on the performances of electric vehicles as part of a postal use. The first part is devoted to the modeling of lithium batteries with an equivalent electric circuit model, whose parameters could be identified using linear characterization tests. The second part is dedicated to the study of aging, and results in an aging estimator using data collected from accelerated aging tests programs. Then the postal usage is studied, and a power profile representative of the actual load on the battery is provided. The latter was used to validate the model of the battery in the field of postal use. Then the postal use is studied, and a current profile representative of the real behavior of the battery is provided. This profile was used to validate the model of the battery in the postal use domain. Then a model of electric vehicles is presented, it integrates the battery model, which can simulates the aging state of the battery using the ageing estimator. Finally, the various possible strategies of recharge are listed and compared, which leads to conclusions about their influences on aging of batteries, and the vehicles performance
Labbé, Frédéric. "Étude de l’émergence et de la dynamique évolutive d’Armillaria ostoyae, agent pathogène du pin maritime." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0387/document.
Full textIn the maritime pine (Pinus pinaster) forest of the Landes de Gascogne (south-western France), pine mortality due to the root rot fungus Armillaria ostoyae (Basidiomycete) has been increasing over the last 30 years. The first cases of this disease were reported a few years after a major change in land use which occurred in this region following the replacement of original moors by an intensively managed planted forest. Our aim was to understand the factors driving this disease emergence. For this, we investigated the spatial distribution of pathogen damage related to historical factors, estimated the variation in fungal traits related to parasitism and saprophytism and investigated the demographic history of A. ostoyae. The current distribution of A. ostoyae mortality appeared depending on the pre-existing forests, suggesting that A. ostoyae was commonly distributed in pre-existing forest areas which acted as a reservoir for the colonization of recent planted forests. The rhizomorphs production was significantly correlated with virulence, suggesting that this trait plays an important role in the parasitic stage of A. ostoyae, but no significant relationship between parasitism and saprophytism components was detected, which may suggest that there is no trade-off between these traits. Finally, the best demographic scenario to explain A. ostoyae population structure in the Landes forest is a two step scenario: there was first a decrease and then an expansion in the fungal population, which appeared to follow the dynamics of the host population. The generation time of A. ostoyae was estimated between 10 and 20 years
McGeachie, M. T. "Characterisation of the Sydney region in relation to corrosion, timber decay risk factors and the corrosion of nails in timber in covered conditions." Thesis, 2001. http://handle.uws.edu.au:8081/1959.7/491.
Full textMutenje, Munyaradzi Junia. "Rural livelihoods in south-eastern Zimbabwe : the impact of HIV/AIDS on the use and management of non-timber forestry products." Thesis, 2010. http://hdl.handle.net/10413/8542.
Full textThesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.
Adnan, Muhammad. "Diversity and abundance of medicinal plants among different forest-use types of the Pakistani Himalaya." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-0006-B150-C.
Full text"Defects and Statistical Degradation Analysis of Photovoltaic Power Plants." Master's thesis, 2016. http://hdl.handle.net/2286/R.I.40311.
Full textDissertation/Thesis
Masters Thesis Engineering 2016
Shirvani, Zeinab. "A Holistic Analysis for Spatiotemporal Interdependencies of Deforestation, Forest Degradation and Landslide Susceptibility in NE Iran." 2019. https://tud.qucosa.de/id/qucosa%3A72054.
Full textVerschiedene biotische und abiotische Faktoren verursachen Veränderungen im Wald. Dauerhafte menschliche Eingriffe im Anthropozän könnten nicht nur zu unterschiedlichen Typen von Veränderungen im Wald selbst führen, sondern auch bestehende Naturgefahren verstärken. Trotz verschiedener fernerkundungsgestützter Forschungsarbeiten zu Waldveränderungen besteht Bedarf an einer holistischen Studie, welche verschiedene Dimensionen anthropogen verursachter Waldveränderungen wie Waldverlust, Waldfragmentierung und Waldschädigung aufzeigen kann. Außerdem ist es notwendig, die Auswirkungen derartiger Veränderungen in Naturgefahrenstudien für Waldgebiete zu untersuchen. Ziel dieser Forschung war es, eine holistische Bewertung von langfristigem Waldverlust, Waldfragmentierung und Waldschädigung durchzuführen, die durch menschliche Aktivitäten wie Ausbreitung von Siedlungsgebieten und Ausbau von Straßennetzen im Nordosten des Iran verursacht werden. Darüber hinaus hat diese Forschungsarbeit die Bedeutung der Walddynamik in der Analyse von Rutschungsneigung innerhalb von Waldgebieten untersucht. Um langfristige Waldveränderungen in drei Intervallen zwischen 1966 und 2016 zu untersuchen, wurden Zeitreihen von Landsat-Daten und zusätzlich von Luftbildern verwendet. Die Erweiterung der Waldwege wurde aus einer Kombination von Satellitenbildern und topographischen Karten extrahiert. Für die Analyse von Waldveränderungen wurden sowohl pixel- als auch objektbasierte Ansätze verwendet. Räumliche Autokorrelationsindikatoren und räumliche Regressionsmodelle wurden eingesetzt, um Muster von Waldveränderungen und Zusammenhänge zwischen Waldveränderungen und der Erweiterung von Wohngebieten und Straßennetzen zu visualisieren. Darüber hinaus wurde die Erkennung alter und neuer Erdrutsche aus Sentinel-1 und -2 Bildern und DEM-Derivaten unter Verwendung der objektorientierten „Random Forest “-Methode durchgeführt. Ebenfalls mit dem objektbasierten „Random Forest “-Ansatz wurde die Bedeutung von Konditionierungs- und Auslösefaktoren untersucht, welche die Suszeptibilität einer Fläche für Erdrutsche in geschützten und nicht geschützten Wäldern kontrollieren. Die zentralen Erkenntnisse sind, dass die Ausbreitung von Siedlungsflächen und der Ausbau von Landstraßen die Waldverluste vor dem Jahr 2000 zunehmend erhöht haben. Mit dem Ausbau von Wald- und Bergbaustraßen änderten sich jedoch seit den 1980er Jahren die räumlichen Muster der Walddynamik von Waldverlust hin zu Waldfragmentierung und Walddegradierung. Obwohl die orographischen und hydrologischen Merkmale die wichtigsten Einflussfaktoren hinsichtlich Suszeptibilität für das Auftreten von Erdrutschen in Schutzwäldern waren, haben weitere natürliche und anthropogene Auslöser Signifikanz erreicht innerhalb der nicht geschützten Waldflächen: Holzeinschlag und Waldfragmentierung waren dabei die dominierenden anthropogenen Auslöser. Die Studie bestätigt zudem, dass die Parameter für die Erkennung von Erdrutschen und für die Beurteilung der Rutschungs-Suszeptibilität an die verschiedenen Waldgebiete anzupassen sind. In der Modellierung der Beziehung zwischen Waldveränderungen und anthropogenen Einflüssen zeigten räumlich basierte Regressionsmodelle eine höhere Effizienz als das traditionelle Regressionsmodell; allerdings gab es keine klare Priorität innerhalb der räumlichen Modelle. Der „Random Forest “-Ansatz zeigte eine zufriedenstellende Genauigkeit sowohl bei der Kartierung historischer Erdrutsche als auch in der Bestimmung der Rutschungs-Suszeptibilität. Dabei lag die erreichte Genauigkeit in den geschützten Waldgebieten höher. Diese Forschungsarbeit hat vom Menschen verursachte Waldveränderungen untersucht. Da jedoch auch andere abiotische und biotische Faktoren die geschilderten Veränderungen verursachen können, sind weitere Studien notwendig. Diese könnten z. B. Klimaparameter, Waldbrände, Insektenschädigung und andere Naturgefahren einschließen.
Ewais, AMR. "Longevity of HDPE Geomembranes in Geoenvironmental Applications." Thesis, 2014. http://hdl.handle.net/1974/8640.
Full textThesis (Ph.D, Civil Engineering) -- Queen's University, 2014-02-28 04:59:20.834
Abdi, Omid. "Climate-Triggered Drought as Causes for Different Degradation Types of Natural Forests: A Multitemporal Remote Sensing Analysis in NE Iran." 2019. https://tud.qucosa.de/id/qucosa%3A72323.
Full textKlimagbedingte Waldstörungen nehmen entweder durch Dürre oder durch andere Klimaextreme zu. Dürren können langfristig die Struktur und Funktion der Wälder verändern oder kurzfristig große Störungen wie Baumsterben, Waldbrände und Insektenausbrüche verursachen. Traditionelle Ansätze wie dendroklimatologische Untersuchungen könnten die langfristigen Reaktionen von Waldbäumen auf Dürrebedingungen aufzeigen, sie sind aber auf einzelne Bäume oder lokale Waldbestände beschränkt. Daher werden multitemporale satellitengestützte Ansätze zur ganzheitlichen Bewertung von klimabedingten Waldreaktionen auf regionaler bis globaler Ebene weiterentwickelt. Es gibt jedoch nur wenige Informationen über die Effizienz von Satellitendaten zur Analyse der Auswirkungen von Dürren in verschiedenen Waldbiotopen. Daher sind weitere Studien zur Analyse von Ansätzen und großräumigen Störungen von Dürren erforderlich. Diese Forschung wurde durchgeführt, um die aus Satellitendaten gewonnenen physiologischen Reaktionen der im Nordosten Irans gelegenen kaspischen hyrkanischen Laubwälder auf klimabedingte Dürren auf lokaler und regionaler Ebene zu bewerten. Auf der Grundlage der aus MODIS-Daten abgeleiteten Indizes wurden die 16-tägigen physiologischen Anomalien von Weideland und Wäldern in Bezug auf Wassergehaltsdefizit und Grünverlust analysiert und ihre Variationen räumlich mit monatlichen und intersaisonalen Niederschlagsanomalien von 2000 bis 2016 bewertet. Insbesondere wurden die Dimensionen der Walddürre in Verbindung mit den Dimensionen der meteorologischen und hydrologischen Dürre bewertet. Großräumige Auswirkungen von Dürren wurden in Bezug auf Baumsterblichkeit, Insektenausbrüche und Waldbrände mit Hilfe von Feldbeobachtungen, multitemporalen Landsat- und TerraClimate Daten untersucht. Verschiedene Ansätze wurden ausgewertet, um Waldreaktionen auf Klimagefahren wie traditionelle Regressionsmodelle, räumliche Autokorrelationen, räumliche Regressionsmodelle und Paneldatenmodelle zu untersuchen. Die wichtigsten Ergebnisse zeigten, dass die Anomalien von Weideland positive Reaktionen auf monatliche und intersaisonale Niederschlagsanomalien aufweisen. Die Dürren in den Wäldern waren jedoch in hohem Maße mit Temperaturerhöhungen und Evapotranspiration verbunden und standen in geringem Zusammenhang mit dem Rückgang von Niederschlägen und des Oberflächenwasserspiegels. Die Gefährdungsintensität von Dürren hat den Wassergehalt von Wäldern stärker beeinflusst als die Eigenschaften ihres Blattgrüns. Die Stufen mittlerer bis extremer Baumsterblichkeit waren signifikant mit der Gefährdungsintensität des Defizits des Wassergehalts der Wälder verbunden. Das Ausmaß der starken Entlaubung hing jedoch nur mit der Gefährdungsintensität des Grünverlustes der Wälder zusammen. Die Klimagefahren haben zu deutlichen Insektenausbrüchen und Waldbränden geführt. Obwohl Maximaltemperaturen, Niederschlagsdefizite, fehlende Bodenfeuchte und Waldbrände des Vorjahres deutlich Insektenausbrüche auslösen konnten, waren die Maximaltemperaturen die einzigen signifikanten Auslöser von Waldbränden von 2010 bis 2017. Neben den Klimafaktoren können auch umweltbedingte und anthropogene Faktoren den Schweregrad eines Brandes während einer Trockenzeit beeinflussen. Die Gesamtbewertung zeigt Hinweise auf räumliche Zusammenhänge zwischen aus Satellitendaten abgeleiteten Waldstörungen und Klimagefahren. Weitere Untersuchungen sind erforderlich, um Ansätze anzuwenden, die mit großen Datenmengen umgehen können, die Satellitendaten in einer hohen spektralen Auflösung für die großmaßstäbige Kartierung von Waldstörungen verwenden und die klimabedingte Waldstörungen von denen zu unterscheiden, die durch andere biotische und abiotische Faktoren verursacht werden.
Kim, Myung Hee 1982. "Factors Affecting Biodefluorination of Fluorotelomer Alcohols (FTOHs): Degradative Microorganisms, Transformation Metabolites and Pathways, and Effects of Co-substrates." Thesis, 2012. http://hdl.handle.net/1969.1/148234.
Full textSepuru, Terrence Koena. "Assessing the use of multispectra remote sensing in mapping the spatio-temporal variations of soil erosion in Sekhukhune District, South Africa." Thesis, 2018. http://hdl.handle.net/10386/2406.
Full textSoil erosion, which is a critical component of land degradation, is one of the serious global environmental problems often threatening food security, water resources, and biodiversity. A comprehensive assessment and analysis of remote sensing applications in the spatial soil erosion mapping and monitoring over time and space is therefore, important for providing effective management and rehabilitation approaches at local, national and regional scales. The overall aim of the study was to assess the use of multispectral remote sensing sensors in mapping and monitoring the spatio-temporal variations in levels of soil erosion in the former homelands of Sekhukhune district, South Africa. Firstly, the effectiveness of the new and freely available moderate-resolution multispectral remote sensing data (Landsat 8 Operation Land Imager: OLI and Sentinel-2 Multi-Spectral Instrument: MSI) derived spectral bands, vegetation indices, and a combination of spectral bands and vegetation indices in mapping the spatio-temporal variation of soil erosion in the former homelands of Sekhukhune District, South Africa is compared. The study further determines the most optimal individual sensor variables that can accurately map soil erosion. The results showed that the integration of spectral bands and spectral vegetation indices yielded high soil erosion overall classification accuracies for both sensors. Sentinel-2 data produced an OA of 83, 81% whereas Landsat 8 has an OA of 82.86%. The study further established that Sentinel-2 MSI bands located in the NIR (0.785-0.900 μm), red edge (0.698-0.785μm) and SWIR (1.565-2.280 μm) regions were the most optimal for discriminating degraded soils from other land cover types. For Landsat 8 OLI, only the SWIR (1.560-2.300 μm), NIR (0.845-0.885 μm) region were selected as the best regions. Of the eighteen spectral vegetation indices computed, Normalized Difference Vegetation Index (NDVI) and Soil Adjusted Vegetation Index (SAVI) and Global Environmental Monitoring Index (GEMI) were selected as the most suitable for detecting and mapping soil erosion. Secondly, the study assessed soil erosion in the former homelands of Sekhukhune, South Africa by applying a time-series analysis (2002 and 2017), to track changes of areas affected by varying degrees of erosion. Specifically, the study assessed and mapped changes of eroded areas (wet and dry season), using multi-date Landsat products 8 OLI and 7 Enhanced Thematic Mapper (ETM+)). Additionally, the study used extracted eroded areas and overlay analysis was performed together with geology, slope and the Topographic Wetness Index (TWI) of the area under study to assess whether and to what extent the observed erosional trends can be explained. ii Time series analysis indicated that the dry season of 2002, experienced 16.61 % (224733 ha) of erosion whereas in 2017 19.71% was observed. A similar trend was also observed in the wet season. This work also indicates that the dominant geology type Lebowa granite: and Rustenburg layered its lithology strata experienced more erosional disturbances than other geological types. Slopes between 2-5% (Nearly level) experienced more erosion and vice-versa. On the hand, the relationship between TWI and eroded areas showed that much erosion occurred between 3 and 6 TWI values in all the seasons for the two different years, however, the dry season of 2002 had a slightly higher relationship and vice-versa. We, therefore, recommend use and integration of freely and readily available new and free generation broadband sensors, such as Landsat data and environmental variables if soil erosion has to be well documented for purposes of effective soil rehabilitation and conservation. Keywords: Food security Global changes, Land degradation, Land-based ecosystems, Land management practices, Satellite data, Soil conservation, Sustainable Development; Topographic Wetness Index; Time series analysis.
Krause, Jakob. "Kontextsensitive Prognoseverfahren für das Abnutzungsverhalten von technischen Systemen." Doctoral thesis, 2013. https://tud.qucosa.de/id/qucosa%3A27376.
Full textTechnical systems are prone to deterioration. This leads to negative consequences like break-downs. Maintenance actions are executed in order to transfer technical systems back into healthy states. If break downs occur suddenly, the consequences can be dramatic. Therefore, it is reasonable to schedule maintenance actions based on health-state predictions. Thereby, health state predictions are impeded by the fact that technical systems often deteriorate variably, depending on certain stress factors. Furthermore, the effects of variable deterioration behavior can be hidden by system specific behavior. Thus, approaches are shown which integrate variable deterioration behavior into healthstate predictions while influences caused by the system specific behavior are considered. Consequently, maintenance actions can be scheduled more efficiently which spares resources and reduces costs.