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Dissertations / Theses on the topic 'Moisture level'
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Fellows, Linda Mary Patricia. "Moisture absorption in low level porosity, thermoplastic toughened epoxy composites." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287317.
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Low, Deborah. "Influence of Streptococcus thermophilus MR-1 C Capsular Exopolysaccharide on Cheese Moisture Level." DigitalCommons@USU, 1998. https://digitalcommons.usu.edu/etd/5440.
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This study investigated the role of exopolysaccharide (EPS) in cheese moisture retention. Analysis of low-fat Mozzarella cheese made with different combinations of EPS-producing (Streptococcus thermophilus MR-1C and Lactobacillus delbrueckii ssp. bulgaricus MR-lR) and non-EPS-producing (S. thermophilus TA061 and L. helveticus LH100) starters showed significantly higher moisture levels in cheese made with S. thermophilus MR-1C. To determine if the S. thermophilus MR-1C EPS was responsible for increased moisture retention, gene replacement was used to inactivate the epsE gene in this bacterium. Low-fat Mozzarella cheese made with L. helveticus LH100 plus the EPS-negative mutant, S. thermophilus DM1O, had significantly lower moisture content than cheese made with LH100 and MR-1C, which confirmed that the MR-1C capsular EPS was responsible for the water-binding properties of this bacterium in cheese. Chemical analysis of the S. thermophilus MR-lC EPS indicated that it had a repeating unit composed of D-galactose, L-rhamnose, and L-fucose in a ratio of 5:2:1. Interestingly, carbohydrate utilization tests showed that DMlO had acquired the ability to ferment galactose.
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Zhang, Hongjuan [Verfasser]. "Improved characterization of root zone soil moisture by assimilating groundwater level and surface soil moisture data in an integrated terrestrial system model / Hongjuan Zhang." Jülich : Forschungszentrum Jülich GmbH, Zentralbibliothek, 2018. http://d-nb.info/1163839310/34.
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Verrot, Lucile. "Modeling long-term variability and change of soil moisture and groundwater level - from catchment to global scale." Doctoral thesis, Stockholms universitet, Institutionen för naturgeografi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-128322.
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The water stored in and flowing through the subsurface is fundamental for sustaining human activities and needs, feeding water and its constituents to surface water bodies and supporting the functioning of their ecosystems. Quantifying the changes that affect the subsurface water is crucial for our understanding of its dynamics and changes driven by climate change and other changes in the landscape, such as in land-use and water-use. It is inherently difficult to directly measure soil moisture and groundwater levels over large spatial scales and long times. Models are therefore needed to capture the soil moisture and groundwater level dynamics over such large spatiotemporal scales. This thesis develops a modeling framework that allows for long-term catchment-scale screening of soil moisture and groundwater level changes. The novelty in this development resides in an explicit link drawn between catchment-scale hydroclimatic and soil hydraulics conditions, using observed runoff data as an approximation of soil water flux and accounting for the effects of snow storage-melting dynamics on that flux. Both past and future relative changes can be assessed by use of this modeling framework, with future change projections based on common climate model outputs. By direct model-observation comparison, the thesis shows that the developed modeling framework can reproduce the temporal variability of large-scale changes in soil water storage, as obtained from the GRACE satellite product, for most of 25 large study catchments around the world. Also compared with locally measured soil water content and groundwater level in 10 U.S. catchments, the modeling approach can reasonably well reproduce relative seasonal fluctuations around long-term average values. The developed modeling framework is further used to project soil moisture changes due to expected future climate change for 81 catchments around the world. The future soil moisture changes depend on the considered radiative forcing scenario (RCP) but are overall large for the occurrence frequency of dry and wet events and the inter-annual variability of seasonal soil moisture. These changes tend to be higher for the dry events and the dry season, respectively, than for the corresponding wet quantities, indicating increased drought risk for some parts of the world.
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Baggaley, Nicola J. "Modelling the drivers of soil moisture in the landscape in order to apply the STAMINA model at a regional level." Thesis, Cranfield University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443723.
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Ellingson, Jordan M. "Starch Resin Moisture Level Effect on Injection Molding Processability and Molded Part Mechanical Properties with Pure Starch Resin and Polymer Blends." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3782.
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The current and forecasted global consumption of plastic packaging and products through the 21st century combined with the already reported and growing negative impact of plastics on the environment due to plastics being synthesized from nonrenewable resources that do not biodegrade is of serious concern. However, recent advances in starch technology including the development of thermoplastic starch (TPS) materials —polymers that are both renewable and biodegradable—have brought hope to reducing this impact. The mechanical properties of thermoplastic starch have often been improved by blending with synthetic polymers. One issue that arises with blending is volatilization of the melt from moisture in the TPS materials. Ecostarch™ a proprietary, pelletized thermoplastic starch resin formulated from potato starch, was processed and tested to observe injection molding processability at various moisture levels, in pure TPS as well as various blend ratios with high-density polyethylene (HDPE) and polypropylene (PP). This study evaluated and analyzed the effects of the TPS pellet moisture content on void formation in the plastic pre-injection melt and subsequent molded part mechanical properties. Statistical analysis of the test results showed that moisture had a significant effect on void formation in the plastic melt. In TPS/HDPE blends, voids percent (as measured by cross section area) increased by 300-350% from 0.6% to 1.4% moisture levels. In unblended TPS, void percent increased by 150% from 0.4% to 1.4% moisture levels. In the unblended TPS parts, impact strength (energy in ft-lb) was decreased by 1% from 0.6% to 1.4% moisture level. In the TPS/HDPE and TPS/PP blends, there was no significant effect on impact strength due to the moisture percent levels of the TPS. Modulus decreased by 25% from 0.4% to 1.4% moisture level in unblended TPS parts. From 0.6% to 1.4% change in TPS moisture content, the modulus of the TPS/HDPE blend decreased by 9% at a 30% TPS/70% HDPE blend and decreased by 14% at a 70% TPS/30% HDPE blend. Though the moisture of TPS did not have a significant impact on the tensile strength of TPS/HDPE blends, the tensile strength of TPS/PP blend samples were significantly affected: a change from 0.6% to 1.4% moisture increased tensile strength 34% at a 70% TPS/30% PP blend and increased tensile strength by 22% at a 30% TPS/70% PP blend. Thus the results of this study highlight the relationships between moisture, voids, and mechanical performance of TPS and TPS/Polymer blends.
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Park, Seongho. "Materials, Processes, and Characterization of Extended Air-gaps for the Intra-level Interconnection of Integrated Circuits." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22598.
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Materials, Processes, and Characterization of Extended Air-gaps for the Intra-level Interconnection of Integrated Circuits
Seongho Park
157 pages
Directed by Dr. Paul A. Kohl and Dr. Sue Ann Bidstrup Allen
The integration of an air-gap as an ultra low dielectric constant material in an intra-metal dielectric region of interconnect structure in integrated circuits was investigated in terms of material properties of a thermally decomposable sacrificial polymer, fabrication processes and electrical performance. Extension of the air-gap into the inter-layer dielectric region reduces the interconnect capacitance. In order to enhance the hardness of a polymer for the better process reliabilities, a conventional norbornene-based sacrificial polymer was electron-beam irradiated. Although the hardness of the polymer increased, the thermal properties degraded. A new high modulus tetracyclododecene-based sacrificial polymer was characterized and compared to the norbornene-based polymer in terms of hardness, process reliability and thermal properties. The tetracyclododecene-based polymer was harder and showed better process reliability than the norbornene-based sacrificial polymer. Using the tetracyclododecene-based sacrificial polymer, a single layer Cu/air-gap and extended Cu/air-gap structures were fabricated. The effective dielectric constant of the air-gap and extended air-gap structures were 2.42 and 2.17, respectively. This meets the requirements for the 32 nm node. Moisture uptake of the extended Cu/air-gap structure increased the effective dielectric constant. The exposure of the structure to hexamethyldisilazane vapor removed the absorbed moisture and changed the structure hydrophobic, improving the integration reliability. The integration processes of the air-gap and the extended air-gap into a dual damascene Cu metallization process has been proposed compared to state-of-the-art integration approaches.
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Fröhlich, Elsa Luise [Verfasser], Andreas [Akademischer Betreuer] Fink, Michael [Akademischer Betreuer] Kerschgens, and Peter [Akademischer Betreuer] Knippertz. "Upper-level troughs and tropical plumes at low latitudes : identification, climatology and their impact on global moisture transport / Elsa Luise Fröhlich. Gutachter: Andreas Fink ; Michael Kerschgens ; Peter Knippertz." Köln : Universitäts- und Stadtbibliothek Köln, 2012. http://d-nb.info/1038227054/34.
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Copp, Sara Rose. "Community level impacts associated with the invasion of English ivy (Hedera spp.) in Forest Park: a look at the impacts of ivy on community composition and soil moisture." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/2024.
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Invasive species degrade ecosystems by altering natural processes and decreasing the abundance and diversity of native flora. Communities with major fluctuations in resource supply allow invasive species to exploit limiting resources making the community prone to invasion. In the Pacific Northwest, urban forests characterized with limited light and seasonally limited soil moisture are being dominated by nonnative English ivy (Hedera spp). Three observational studies were conducted in the Southern end of Forest Park within the Balch Creek Subwatershed in Portland, Oregon in order to understand 1) how English ivy changes over three growing seasons, 2) how the native understory composition responds to English ivy, 3) if the dominance of English ivy reduces soil moisture to neighboring plants, 4) how English ivy and two co-occurring native herbs (Hydrophyllum tenuipes and Vancouveria hexandra) physiologically respond to seasonal changes in soil moisture. Percent cover of the understory community was collected in both 2010 and 2013 growing seasons in 54 plots in order to understand the change in cover over time. Community response and the relationship with soil moisture was analyzed using percent cover of the understory community and associated environmental variables including soil moisture collected in 128 plots during the 2013 field season. Finally, 15 plots with co-occurring Hedera spp, H. tenuipes and V. hexandra were sampled for stomatal conductance, leaf water potential, and associated environmental variables. Results show ivy cover increases on average 14% between 2010 and 2013 while native understory cover increased on average < 1%. Once ivy forms dense cover over 44% there is a reduction of native richness, diversity and herb cover while also an increase in available soil moisture and deciduous canopy cover. There were disparate impacts to different functional groups and between species. As functional group, the herbaceous community was the most impacted by ivy invasion. The shrubs and fern community had a variable response to ivy invasion. Many of the fern and shrub species least impacted by ivy also had associations with high soil moisture and deciduous canopy cover. Finally, data suggests that ivy does not take advantage of seasonally limiting soil moisture to invade the understory community. This study indicates that English ivy is both efficient at water use and may have the ability to obtain water from distant locations throughout the forest. Once established, ivy has the ability to alter the community composition. Ivy removal and habitat restoration are essential in order to maintain and enhance biodiversity in Forest Park.
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Zhalehjoo, Negin. "Characterisation of the deformation behaviour of unbound granular materials using repeated load triaxial testing." Thesis, Federation University of Australia, 2018. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/166953.
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Unbound Granular Materials (UGMs) are used in the base/subbase layers of flexible pavements for the majority of roads around the world. The deterioration of pavements increases with the increase of traffic loadings. To ensure the long-term performance and serviceability of pavement structures through a realistic design, the precise evaluation and comprehensive characterisation of the resilient and permanent deformation behaviour of pavement materials are essential. The present PhD study aims to investigate the characterisation of the resilient and permanent deformation behaviour of four road base UGMs sourced from quarries in Victoria, Australia, using Repeated Load Triaxial (RLT) testing. The triaxial system used in this study is instrumented with four axial deformation measurement transducers to achieve highly precise measurements and to evaluate the effect of instrumentation on the resilient modulus of UGMs. The resilient Poisson’s ratio of the studied UGMs is also determined using a radial Hall-Effect transducer. Moreover, a series of permanent deformation tests is performed to precisely characterise the axial and radial permanent deformation behaviour of UGMs and investigate the factors that may significantly influence the accumulated axial and radial permanent deformations. Finally, three permanent deformation models incorporated with a time-hardening procedure are employed to predict the magnitude of permanent strain for multiple stress levels of the RLT test. The predictions using the employed models are then compared against the measured values to evaluate the suitability of the models and to identify the model that best predicts the strain accumulation behaviour of the tested UGMs. While this study focuses on the resilient and permanent deformation behaviour of four Victorian UGMs under repeated loading, the knowledge generated from this comprehensive investigation will contribute towards the global development of more reliable methods for evaluating the long-term performance of pavement structures and minimising road maintenance and repair costs.<br>Doctor of Philosophy
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Husman, Stephen H., K. Johnson, and R. Wegener. "Upland Cotton Lint Yield Response to Several Soil Moisture Depletion Levels." College of Agriculture, University of Arizona (Tucson, AZ), 1999. http://hdl.handle.net/10150/197043.
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Upland cotton lint yield response to several soil moisture depletion levels was measured in 1997 and 1998. In 1997, four Upland cotton varieties including DP 5415, DP 33B, DP 5816, and STV 474 were tested. However because of a nonsignificant variety difference in the 1997 test, the 1998 test was planted to a single variety (DP 33B). In 1997 and 1998, depletion of plant available soil water (PAW) irrigation treatments consisted of 35%, 50%, 65%, and 80%. In 1997, all PAW depletion treatments were significantly different with the 35% PAW treatment resulting in the highest average lint yield of 1880 lbs. lint/acre. The 50%, 65%, and 80% PAW treatments resulted in 1410, 1123, and 248 lbs. lint/acre respectively. There was no significant (P<0.05) difference between varieties within all PAW treatments in 1997. In 1998, all PAW depletion treatments again were significantly different with the 35% PAW treatment resulting in the highest average lint yield of 1658 lbs. lint/acre. The 50%, 65%, and 80% PAW treatments resulted in 1534, 1396, and 641 lbs. lint/acre respectively.
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Husman, S., K. Johnson, R. Wegener, and F. Metzler. "Upland Cotton Lint Yield Response to Several Soil Moisture Depletion Levels." College of Agriculture, University of Arizona (Tucson, AZ), 1998. http://hdl.handle.net/10150/210353.
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Upland cotton lint yield response to several soil moisture depletion levels was measured in 1996 and 1997 for four Upland cotton varieties including DP 5415, DP 33B, DP 5816, and STV 474. In 1996, depletion of plant available soil water (PAW) irrigation treatments consisted of 35%, 50%, 75%, and 90%. In 1997, treatments were 35%, 50 %, 65 %, and 80% depletion of PAW. In 1996, the 35% and 50% treatments were significantly different than the 75% and 90% treatments (P < 0.05) and resulted in the highest lint yields of 1374 and 1438 lbs. lint/acre respectively. A lint yield reduction was measured with the 75% and 90% PAW treatments of 713 and 329 lbs. lint/acre, respectively. The 75% and 90% treatments were significantly different than the 35% and 50% treatments and were significantly different from each other. In 1997, all PAW depletion treatments were significantly different with the 35% PAW treatment resulting in the highest average lint yield of 1880 lbs. lint/acre. The 50%, 65%, and 80% PAW treatments resulted in 1410, 1123, and 248 lbs. lint/acre respectively. There was no significant (P < 0.05) difference between varieties within all PAW treatments in 1996 or1997.
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Semon, Mande 1957. "Interplot and intraplot border effects on maize genotypes under two levels of moisture availability." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276817.
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The performance of three maize (Zea mays L.) hybrids, grown under two irrigation levels, was used to investigate the effects of soil moisture competition between adjacent plots, the transmission of these effects into multi-row adjacent plots and types of multi-row plots and plot borders most effective in shielding from these interplot competition effects. On the basis of grain yield, competition effects intended to the second rows of five-row plots necessitating more than five-row plots to accurately evaluate the full transmission of interplot competition effects into adjacent plots. Evaluation of genotypes in one-row plots all with the same common border row genotype to make them three-row plots would be more suitable for evaluation of relative competitiveness for soil moisture under soil moisture stress conditions compared to no border rows or border rows of the same genotype being evaluated.
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Bias, Calisto A. L. F. "The performance of maize (Zea mayz, L.) inbred lines under different moisture and nitrogen levels." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326191.
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Silva, Gyrlene Aparecida Mendes da. "Evolução dos eventos El Niños em fases distintas da Oscilação Decadal do Pacífico: impactos no Jato de Baixos Níveis a leste dos Andes e nos ciclones extratropicais da América do Sul." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/14/14133/tde-11092009-091218/.
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Neste trabalho foi investigado o impacto da evolução dos eventos El Niño (EN) de acordo com as fases distintas da Oscilação Decadal do Pacífico (positiva, ODP(+) e negativa, ODP(-)) nas mudanças no transporte de umidade sobre o Sudeste da América do Sul (SEAS) durante o verão austral de 1950-1999. A resposta da variabilidade do Jato de Baixos Níveis a leste do Andes (JBN) e de algumas propriedades dos ciclones extratropicais sobre o cone sul do continente as modificações na circulação associadas aos eventos mencionados acima foi analisada. Foi mostrado que existem poucas mudanças significativas no regime de precipitação sobre a América do Sul ao se considerar a influência dos anos neutros do Pacífico Equatorial durante a ODP(+) quando comparado com os anos da ODP(- ). Entretanto, os eventos EN da ODP(+) indicam diferenças no padrão de anômalo de ondas em altos níveis em resposta as diferentes anomalias de Temperatura de Superfície do Mar (TSM) dos oceanos Pacífico e Atlântico Equatorial quando comparado com os eventos da ODP(-). Como conseqüência foram observadas anomalias positivas de precipitação no SEAS associadas à intensificação do fluxo convergente de umidade em baixos níveis oriundo do Atlântico Equatorial e região Amazônica para esta região durante os eventos EN da ODP(+). Todavia, os eventos da ODP(-) apresentaram anomalias positivas de precipitação apenas ao sul do SEAS e negativas ao norte desta como resposta ao movimento descendente e divergência anômala sobre o centro-leste do Brasil seguido de enfraquecimento do fluxo de umidade transportado pelos ventos alísios em direção aos subtrópicos. Os experimentos numéricos com Community Atmosphere Model versão 3.0 serviram para ajudar na interpretação das análises observacionais onde foi sugerido que o fenômeno EN é mais importante para forçar as anomalias climáticas de verão do continente do que o modo de ODP. A maior freqüência de casos de JBN detectados com o critério 1 de Bonner durante anos de EN da ODP(+) em relação a ODP(-) foi proporcional à quantidade de eventos selecionados em cada categoria. Em geral, os casos de JBN anômalo se deslocaram desde a Amazônia até o Sul do Brasil e Nordeste da Argentina, mas foi na ODP(-) que o sistema foi mais intenso apesar de apresentar menor potencial para o transporte de umidade para o SEAS quando comparado com os casos da ODP(+). Através do esquema numérico de Murray e Simmonds foi observado que, coerentemente com a intensificação do fluxo convergente de ar quente e úmido dos trópicos para o SEAS, os eventos EN da ODP(+) apresentaram ciclones extratropicais mais freqüentes e com pressões centrais mais baixas sobre o extremo Sul do Brasil, Uruguai, Nordeste da Argentina e vizinhanças do Atlântico Sudoeste em comparação com os eventos da ODP(-).<br>This work investigates the impact of the El Niño (EN) events and their evolution according to the PDO phases (warm, PDO(+) and cold, PDO(-)) focusing on the moisture transport exchanges from the north to the Southeast of the South America (SESA) during the austral summer period of 1950-1999. The variability of the Low Level Jet east of the Andes (LLJ) and some properties of extratropical cyclones over the southern cone of the continent in response to the modifications in the atmosphere circulation due to above mentioned events is analyzed. It is shown that on the South America continent there are not any significant changes in precipitation distribution during the neutral years in the Equatorial Pacific for PDO(+) when compared to the years of PDO(-). However, the EN events during PDO(+) indicate some differences in the anomalous wave pattern at high levels due to the variability of the Sea Surface Temperature (SST) anomalies on the Equatorial Pacific and Atlantic oceans when compared with the events for PDO(-). This implies in positive precipitation anomalies over the SESA which is associated to the enhancement of convergent moisture flux in this region. However, the events for PDO(-) showed positive precipitation anomalies only over the southern part of the SEAS and negative to the north which is associated to the downward motion and anomalous divergence over the centraleastern Brazil. This pattern may have contributed for weakening the moisture flux transported by the trade winds towards the subtropics. Numerical experiments with the Community Atmosphere Model version 3.0 also helped on the interpretation of the observational analysis where was suggested that EN events are more important to force the climate anomalies in the summer season over the continent than the PDO mode. The frequency of LLJ cases detected with the Bonner criterion 1 during the years of EN for PDO(+) is bigger than for PDO(-). The spatial position pattern for both categories of the anomalous LLJ is from the Amazon to Southern Brazil and Northeastern Argentina. During the PDO(-) the jet is more intense, however it seems to transport less moisture towards the SEAS region when compared to the PDO(+) cases. The extratropical cyclones tracked through a numerical scheme showed higher frequency and lower central pressures on the extreme of Southern Brazil, Uruguay, Northeastern Argentina and around the Southwest Atlantic during the EN events of PDO(+) when compared to the events of PDO(-). This is in agreement with the largest flux convergence of warm and humid air from the tropics to these areas.
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Nleya, Thandiwe Mildred. "Rooting pattern and seed yield of selected pinto bean genotypes under different levels of soil moisture." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq23966.pdf.
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Bisso, Eya Joseph 1955. "The effects of maturity differences on competition between adjacent rows of Sorghum bicolor varieties at two levels of soil moisture." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276972.
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The objective of the study was to determine if and how grain sorghum hybrids (Sorghum bicolor (L.) Moench) of different maturity dates compete with one another when planted in adjacent rows under different moisture levels. Five sorghum varieties differing in their maturity were used: Taylor Evans Y-101-G coming to mid-bloom in 71 days, RS 610, Asgrow Corral, DK 64 and DK 69 coming to mid-bloom in 56.9 days, 61 days, 69.3 days and 75.6 days respectively. Six agronomic characters were measured to determine the effect and extent of competition. They included the number of days to mid-bloom, tiller ratio, grain yield, grain test weight and 300-seed weight. According to the results, adjacent row competition took place due to differences in maturity date for grain yield and 300-seed weight. An almost equilibrium appeared between loss or gain of border rows compared to the loss or gain of the middle row. Also the length of time between day to mid-bloom of the border rows hybrids and the center row genotype was important in the extent of competition effects.
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Roussel, Nicolas. "Application de la réflectométrie GNSS à l'étude des redistributions des masses d'eau à la surface de la terre." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30327/document.
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La réflectométrie GNSS (ou GNSS-R) est une technique de télédétection originale et pportuniste qui consiste à analyser les ondes électromagnétiques émises en continu par la soixantaine de satellites des systèmes de positionnement GNSS (GPS, GLONASS, etc.), qui sont captées par une antenne après réflexion sur la surface terrestre. Ces signaux interagissent avec la surface réfléchissante et contiennent donc des informations sur ses propriétés. Au niveau de l'antenne, les ondes réfléchies interfèrent avec celles arrivant directement des satellites. Ces interférences sont particulièrement visibles dans le rapport signal-sur-bruit (SNR, i.e., Signal-to-Noise Ratio), paramètre enregistré par une station GNSS classique. Il est ainsi possible d'inverser les séries temporelles du SNR pour estimer des caractéristiques du milieu réfléchissant. Si la faisabilité et l'intérêt de cette méthode ne sont plus à démontrer, la mise en oeuvre de cette technique pose un certain nombre de problèmes, à savoir quelles précisions et résolutions spatio-temporelles peuvent être atteintes, et par conséquent, quels sont les observables géophysiques accessibles. Mon travail de thèse a pour objectif d'apporter des éléments de réponse sur ce point, et est axé sur le développement méthodologique et l'exploitation géophysique des mesures de SNR réalisées par des stations GNSS classiques. Je me suis focalisé sur l'estimation des variations de hauteur de l'antenne par rapport à la surface réfléchissante (altimétrie) et de l'humidité du sol en domaine continental. La méthode d'inversion des mesures SNR que je propose a été appliquée avec succès pour déterminer les variations locales de : (1) la hauteur de la mer au voisinage du phare de Cordouan du 3 mars au 31 mai 2013 où les ondes de marées et la houle ont pu être parfaitement identifiées ; et (2) l'humidité du sol dans un champ agricole à proximité de Toulouse, du 5 février au 15 mars 2014. Ma méthode permet de s'affranchir de certaines restrictions imposées jusqu'à présent dans les travaux antérieurs, où la vitesse de variation verticale de la surface de réflexion était supposée négligeable. De plus, j'ai développé un simulateur qui m'a permis de tester l'influence de nombreux paramètres (troposphère, angle d'élévation du satellite, hauteur d'antenne, relief local, etc.) sur la trajectoire des ondes réfléchies et donc sur la position des points de réflexion. Mon travail de thèse montre que le GNSS-R est une alternative performante et un complément non négligeable aux techniques de mesure actuelles, en faisant le lien entre les différentes résolutions temporelles et spatiales actuellement atteintes par les outils classiques (sondes, radar, diffusiomètres, etc.). Cette technique offre l'avantage majeur d'être basé sur un réseau de satellites déjà en place et pérenne, et est applicable à n'importe quelle station GNSS géodésique, notamment celles des réseaux permanents (e.g., le RGP français). Ainsi, en installant une chaîne de traitement de ces acquisitions de SNR en domaine côtier, il serait possible d'utiliser les mesures continues des centaines de stations pré-existantes, et d'envisager de réaliser des mesures altimétriques à l'échelle locale, ou de mesurer l'humidité du sol pour les antennes situées à l'intérieur des terres<br>GNSS reflectometry (or GNSS-R) is an original and opportunistic remote sensing technique based on the analysis of the electromagnetic waves continuously emitted by GNSS positioning systems satellites (GPS, GLONASS, etc.) that are captured by an antenna after reflection on the Earth's surface. These signals interact with the reflective surface and hence contain information about its properties. When they reach the antenna, the reflected waves interfere with those coming directly from the satellites. This interference is particularly visible in the signal-to-noise ratio (SNR) parameter recorded by conventional GNSS stations. It is thus possible to reverse the SNR time series to estimate the reflective surface characteristics. If the feasibility and usefulness of thismethod are well established, the implementation of this technique poses a number of issues. Namely the spatio-temporal accuracies and resolutions that can be achieved and thus what geophysical observables are accessible.The aim of my PhD research work is to provide some answers on this point, focusing on the methodological development and geophysical exploitation of the SNR measurements performed by conventional GNSS stations. I focused on the estimation of variations in the antenna height relative to the reflecting surface (altimetry) and on the soil moisture in continental areas. The SNR data inversion method that I propose has been successfully applied to determine local variations of : (1) the sea level near the Cordouan lighthouse (not far from Bordeaux, France) from March 3 to May 31, 2013, where the main tidal periods and waves have been clearly identified ; and (2) the soil moisture in an agricultural plot near Toulouse, France, from February 5 to March 15, 2014. My method eliminates some restrictions imposed in earlier work, where the velocity of the vertical variation of the reflective surface was assumed to be negligible. Furthermore, I developed a simulator that allowed me to assess the influence of several parameters (troposphere, satellite elevation angle, antenna height, local relief, etc.) on the path of the reflected waves and hence on the position of the reflection points. My work shows that GNSS-R is a powerful alternative and a significant complement to the current measurement techniques, establishing a link between the different temporal and spatial resolutions currently achieved by conventional tools (sensors, radar, scatterometer, etc.). This technique offers the major advantage of being based on already-developed and sustainable satellites networks, and can be applied to any GNSS geodetic station, including permanent networks (e.g., the French RGP). Therefore, by installing a processing chain of these SNR acquisitions, data from hundreds of pre-existing stations could be used to make local altimetry measurements in coastal areas or to estimate soil moisture for inland antennas
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Berg, Karin. "Simulations of groundwater levels and soil water content : Development of a conceptual hydrological model with a continous soil profile." Thesis, Linköping University, Department of Thematic Studies, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1910.
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<p>Transport of chemical substances through a catchment depend to a large extent on the water content of the soil through which they are transported. When the groundwater level rise and fall, redox conditions change in the soil and the transport of substances is affected. </p><p>The aim of this study is to develop a hydrological model which is able to simulate soil water content at different depths and groundwater level in a soil profile. A new type of conceptual model is developed, which uses a continous represenation of the soil and soil water from the soil surface down to the bedrock. The model is intended to be applied on small catchments at a later stage. </p><p>The results show that the simulation of groundwater levels was greatly improved compared to previous results. Simulation of soil water content at selected depths is not yet satisfactory. The runoff simulation was accurate at one of the sites but did not work as well at the other. At one of the sites it was also possible to combine good simulations of runoff and groundwater levels but at the other it was only possible to obtain acceptable simulations of either runoff or groundwater. </p><p>It is suggested that model performance could be improved by letting the porosity decrease and the soil water content increase non-linearly with depth. Calculations of evaporation from soil and runoff also need to be modified.</p>
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Terrell, Mark A. "Sensitivity of northern red oak (Quercus rubra L.) to variation of temperature and moisture availability along latitudinal and longitudinal climate gradients." Virtual Press, 2002. http://liblink.bsu.edu/uhtbin/catkey/1247896.
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Spatial distribution of species and thus the composition of deciduous forests are expected to change in response to global climatic warming. Climate-growth response algorithms in forest simulation models that represent the influence of climate on tree growth are based on the geographic range limits of a species. These models assume that temperature limitations control the latitudinal range boundaries for tree species in the eastern United States, and that water limitations control the western range boundary. This study investigated spatial variation of tree-growth responses to historical variations in climate using tree-ring data for Quercus rubra L. from 71 study sites across latitudinal and longitudinal temperature and precipitation gradients in eastern North America. Correlation analyses were used to identify significant site-specific associations between radial growth indices and 130 climate variables for the common time interval 1930-1980. Geographic information systems (GIS), and Mantel and partial Mantel spatial correlation analyses were used to map, identify, and measure spatial associations between oak sensitivity to climate and regional climate patterns to test the hypothesis that climate controls the spatial distributions of species range limits.Seasonal climate variables exhibited the strongest correlations with radial growth most consistently across the 71 study sites. However, spatial patterns in regional climate were only weakly associated with spatial variation in red oak sensitivity to climate variables. Contrary to expectations, correlations between red oak radial growth indices and temperature variables at northern and southern sites were not significant, failing to support the hypothesis that latitudinal range limits are defined by temperature effects on mature tree growth. High early growing season temperature reduced growth mostly at sites in the southwest region, which concomitantly experienced high inter-annual variability in soil moisture. Increased early growing season site water balance and precipitation was associated with greater radial growth in the western third of red oak's range, partially supporting the hypothesis that the western range limit is defined by limited water availability. These results indicate that climate only partially determines range limit locations; thus model projections may exaggerate forest responses to climate change.<br>Department of Biology
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Keeney, Andrea Brooke. "Effects of Potassium Source and Rate on Yield, Quality, and Leaf Chemistry of Dark and Burley Tobacco, and Residual Effects of Soil K Levels." UKnowledge, 2019. https://uknowledge.uky.edu/pss_etds/120.
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Field trials were conducted in 2016, 2017 and 2018 with dark fire-cured, dark air-cured, and burley tobacco at Princeton, Murray and Lexington Kentucky. Tobacco variety used in 2016 was a low converter (LC) variety, varieties used in 2017 and 2018 were LC and higher converter (HC) varieties. Potassium sources used at all locations and in all years were potassium sulfate (K2SO4) and potassium chloride (KCl). Application rates used at all locations and in all years were 93, 186, 279 kg K ha-1along with an untreated control that received no potassium. In all trials, tobacco that was treated with either potassium source yielded numerically higher than the untreated control. In seven out of 10 trials, LC varieties had a higher moisture content than HC varieties. Tobacco treated with KCl had higher chloride levels than tobacco treated with K2SO4.Quality grade index was similar for tobacco treated with KCl compared to tobacco treated with K2SO4. In all trials, tobacco treated with KCl had numerically lower Tobacco Specific Nitrosamines (TSNA) levels than tobacco treated with K2SO4. Reductions in TSNA levels were 30% lower in tobacco treated with KCl compared to tobacco treated with K2SO4.
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Mkpong, Offiong Etim. "The effects of variable moisture levels on extractable Bray-l P, Bray-l Al, Bray-l Fe, Bray-l Mn : fertilizer P recommendation based on quicktest technique /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487329662144707.
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Lorber, Jean Herault. "Effects of alternative silvicultural practices on oak regeneration in the southern Appalachians." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/35166.
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The regeneration in oak-dominated stands following five silvicultural treatments was examined on four sites in the mountains of Virginia and West Virginia. Treatments included: silvicultural clearcut, leave-tree, commercial clearcut, shelterwood, and group selection. The effects of harvesting were compared among sites and among treatments. Oak regeneration dominance, measured by the relative density of dominant and codominant oak regeneration, was the most important variable calculated from the data. Oak regeneration dominance varied by site, but did not vary by silvicultural treatment; all treatments resulted in relatively low numbers. Therefore, the silvicultural treatments used here were not enough to overcome the site specific limitations to successful oak regeneration. Oak species also seemed to be less important in the regenerating stands than in their parent stands. The biggest losses in oak importance occurred on the intermediate and high quality sites; competitive oak regeneration was relatively scarce on two of the three sites with an oak site index (base age 50) of over 70 ft. Multiple linear regression analysis was used to identify the factors controlling oak regeneration at a smaller scale. The most important variables were those that described the oak stump sprouting potential, the understory and overstory oak component in the pre-harvest stand, post-harvest light and soil nitrogen levels.<br>Master of Science
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Johansson, Martin. "Hårdgörning av Asp." Thesis, Växjö University, School of Technology and Design, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-2291.
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<p>Hårdgörning av trä syftar till att göra materialet hårdare. Detta går att åstadkomma genom komprimering, det komprimerade materialet tenderar dock att återgå mot sin ursprungsform då materialet utsätts för fukt om ingen låsning sker. Låsningen kan ske mekaniskt i en treskiktskonstruktion som motverkar träets fuktrörelser. Dessa skivor har dock visat sig vara instabila och tidigare försök har uppvisat deformationer i form av kupning. Denna undersökning syftar till att utreda förutsättningarna för att använda komprimerad asp samt att ta fram underlag för framtagning av en kommersiell produkt.</p><p>Praktiska tester har genomförts för att studera hårdhet, återfjädring och densitet hos det komprimerade virket. Vidare har treskiktsskivor tagits fram för att testa om det går att få en stabil konstruktion genom att variera tjockleken på spärrskiktet. Även skillnader i acklimatiseringstid och fuktkvotens inverkan för virkets återfjädring har studerats.</p><p>Resultaten visar på att aspens hårdhet efter komprimering blir i samma nivå som bok och ask, en låg fuktkkvot vid komprimering av materialet ger en låg återfjädring, komprimerat material har en längre acklimatiseringstid till jämviktsfuktkvot och materialet går att låsa tvärs fiberriktningen i en treskiktskonstruktion.</p><br><p>To make wood harder it can be densified. This can be achieved by compression, the compressed material tends to return to the original shape when it is exposed to moisture fluxations and if no form of fixation occurs. The fixation can be done mechanically in a three-layer panel construction which reduce movements in the timber. These panels have been found to be unstable and previous attempts have shown deformations in form of cupping. This study aims to evaluate the conditions for using compressed aspen wood, and to provide a basis for development of a commercial product.</p><p>Practical tests have been conducted to study hardness, springback and density of the compressed wood. In addition, three-layer panels have been developed to test whether it is possible to have a stable construction by varying the thickness of the buttom layer. Differences in acclimatisation time and the moisture contents effect on the springback has aslo been studied.</p><p>The results show that the hardness of aspen wood after compression is in equal levels with beech and ashes, a low moisture contet provides a low springback, compressed timber have a longer time for acclimatisation and it is possible to fixate the material in the direction across the grain in a three-layer panel construction.</p>
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Ji-YenWu and 吳季晏. "Coupled Hygro-Thermo-Mechanical Analysis of Fan-Out Wafer Level Package under Moisture Sensitivity Level Test Condition." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/967y4q.
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Emeterio, Francisco San. "Effect of grinding and moisture level of corn grain on performance of lactating dairy cows." 1998. http://catalog.hathitrust.org/api/volumes/oclc/42902285.html.
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Yu-ChunLiu and 劉俞均. "Effects of moisture content on the emission of DEHP [Di-(2ethylhexyl) phthalate] level from the plastic wallpaper." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/35378590979096393551.
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碩士<br>國立成功大學<br>環境醫學研究所<br>103<br>This study aims to examine the effects of moisture content (MC) on the emission of PAEs level from the plastic building materials – the plastic wallpaper. DEHP is selected as the measured target for the emission profile. The plastic wallpaper with highest DEHP level (2,160.67 μg/g, 0.22%) was adopted in the current experiment. Three experimental conditions with different MC% levels of wallpapers are conducted: (A) without wallpaper (control chamber), (B) 3% (dry wallpaper) and (C) 50% (wallpaper soaked in water for 30 minutes). Air and dust samples were collected every second day over 15 days, and the wipe sample was collected in the last day. Higher DEHP concentrations emitted into the air and deposited on the dust are found with higher MC% of the wallpapers (Figure 1). An increasing trend of DEHP levels are associated with the length of the experiment can be found in the air sample (Table 1). Overall, about 43% higher of total DEHP mass released into air, dust and wipe samples was found in the damp wallpapers (MC = 50%) compared to that in the dry ones (MC = 3%). It is suggested that the material should be got rid of within 4 days once it has been damaged by water because of the emission of DEHP mass was found to be increased from the 4th day. It is the first study to evaluate the effects of material moisture on the emission of sVOCs in indoor environments.
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劉宏偉. "Study of Crop Maturity, Moisture Contain and Stem Level on the Bending and Shearing Characteristics for Napier grass Stem." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/39414841746921123263.
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碩士<br>國立嘉義大學<br>生物機電工程學系研究所<br>98<br>Napier grass with high production and abundant nutrition is one species of the most important forage crop in Taiwan. The different harvest period of Napier grass stem specimens randomly was selected from experimental plot in this study. Fist of all, the experiment in different harvest period, moisture content, stem levels and knife bevel angle was conducted throughout the specimens using the test machine under tension and compression test in static state, and calculated the bending stress, modulus of elastic, shear stress and shearing energy of Napier grass stems. Secondary, the Napier grass stems were cut by a single pendulum impact test apparatus to simulate the shear of the forage harvester in dynamic state. This shear experiment were conducted in the different harvest period and moisture content of Napier grass stems for the crop conditions, and the different knife bevel angle, cutting speed and plant inclination angle under shear test for the mechanical conditions, the effect of shear strength and shear impulse of Napier grass stems would be obtained. The analyze data of results could be as a basic of design the information for the forage harvester.
The result showed that moisture content of Napier grass stems increased as the crop mature increased and towards upper to lower of stem levels. Because of the high mature accumulating more mature fibers at the lower stem levels and higher crop mature of Napier grass, so that the static test of the bending stress, modulus of elastic, shear stress, shear energy and the dynamic test of the shear strength and shear impulse were increased. Its explain that higher crop mature and lower of stem levels needs more energy on the shearing test. Napier grass stem moisture content lower caused stems weak and fragile which also reduced the energy required for the shearing process, and thus the energy to static and dynamic tests of the shear test the smaller the shear impulse. Static tests of the shear stress and shear energy and dynamic tests of the shear strength and shear impulse increased with the knife bevel angle increased. The shear strength of stems increased as the cutting speed and plant inclination angle increased. Its explain that the shear efficiency will be better as the smaller knife bevel angle, the higher cutting speed and smaller plant inclination angle.
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Hsieh, Min-Ken, and 謝旻耕. "Effects of orographically induced low-level moisture convergence and inversion strength on upslope fog: a case study at Xitou." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/44xqwd.
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碩士<br>國立臺灣大學<br>大氣科學研究所<br>107<br>Montane cloud forests (MCF) are characterized by forests that are frequently immersed in clouds or fog so that the interception of cloud/fog water provides extra hydrological input to this ecosystem. In this study, we examine the effects of orographically induced moisture convergence and the fog formation at Xitou valley of Taiwan by ceilometer observation and idealized cloud-resolving simulations. This work is the first attempt to understand the local circulation associated with fog at Xitou using a high-resolution cloud-resolving model. Observation analysis shows that the ceilometer is not only reliable to detect fog occurrence but also provides more information about low-level cloud base evolutions. In a fog case on Jan. 7th, 2016, the low-level cloud base lowering is observed before fog formation on the valley surface, which is also associated with the valley winds at Xitou valley. To understand the processes of the moisture transport associated with the fog formation, we perform idealized simulations using high-resolution vector vorticity equation cloud-resolving model (TaiwanVVM) with realistic land surface processes to evaluate the local circulation associated with the fog development. The simulations indicate that both the upslope winds and the turbulent eddies initiated by the upslope winds are primary local processes to moisten the boundary layer in the valley which leads to fog formation at Xitou. Sensitivity experiments show that local fog duration is controlled by synoptic temperature inversion strength. The results suggest that the effect of orographically induced low-level moisture convergence is the essential process to supply moisture in the Xitou valley, and the capping inversion helps the fog formation by limiting the development of convection and preserves moisture in the valley. The sensitivity experiments also suggest that the fog duration is longer with a stronger temperature inversion.
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Guerth-Schacher, Cordula Christina. "Evaluation of the effects of moisture on the thermal protective performance of fire protective clothing in low level heat exposures." 2007. http://www.lib.ncsu.edu/theses/available/etd-03202007-105438/unrestricted/etd.pdf.
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Ross, Cody. "Assessment of soil water movement and the relative importance of shallow subsurface flow in a near-level Prairie watershed." 2017. http://hdl.handle.net/1993/32058.
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Near-level Prairie landscapes have received limited attention in hydrological research. For this thesis, hydrometric measurements and four tracing experiments were completed at three “riparian-to-stream” sites in the Catfish Creek Watershed (southeastern Manitoba) to enhance Prairie hydrology understanding. First, hydrologic state variables were examined to infer vertical and lateral water movement. Second, tracer data were analyzed to evaluate the relative importance of surface versus subsurface water movement. Results show that hydrologic state variables can be useful for inferring riparian-to-stream water movement. Tracer data also revealed that subsurface water movement can contribute significantly to streamflow during snowmelt- and rainfall-triggered events in the study watershed. This thesis demonstrated that subsurface flow is a significant runoff generation mechanism in Prairie landscapes, thus challenging surface water-focused conceptualizations and management strategies that are traditionally used. The findings summarized in this thesis will be critical to improve the performance of hydrological models when applied to the Prairies.<br>February 2017
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Tseng, I.-Chieh, and 曾怡潔. "Effects of evapotranspiration and infiltration on variations in soil moisture and changes in groundwater levels." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/q37cpq.
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碩士<br>國立中央大學<br>水文與海洋科學研究所<br>107<br>Evapotranspiration (ET) and rainfall infiltration (RI) are primary fluxes of water exchanges between land surface and atmosphere. The objectives of this study is to investigate how ET and RI affect soil moisture and groundwater variations. Integrated hydrometeorology measurements were established at the meteorology station inside the campus of National Central University to provide continued observations for calculations of potential ET, real ET, and RI values. During rainfall wetting period, tensiometers and soil moisture sensors provide estimations of RI and parameters of soil characteristic curves. During non-rainfall drying periods, amounts of real ET were estimated by losses of soil moisture. Changes of soil moisture and groundwater levels were analyzed to investigate connections of soil moisture and groundwater during wetting and drying processes.
Data selected from 2016/12/9 to 2018/9/31 were separated into wet events and dry events. Persistent groundwater flow gradients were observed. For wet events, averaged groundwater inflow and outflow velocities are 0.102 mm/hr and 0.117 mm/hr, respectively. For dry events, averaged groundwater inflow and outflow velocities are 0.1 mm/hr and 0.09 mm/hr, respectively. Long-term averaged (for example: after the rain has just stopped, or intermittent rain events, that is, it is impossible to determine whether it is a dry or wet process event.) groundwater inflow and outflow velocities are 0.041 mm/hr and 0.042 mm/hr, respectively. Regional groundwater inflow and outflow do not have significant effects on changes of groundwater levels.
During rainfall events, the rise of groundwater levels were caused by two different effects. The first one is due to the increase of near surface hydrostatic pressures as the increase groundwater levels were early than that of soil moisture at -400 cm. This hypothesis was supported by insignificant differences between groundwater inflow and outflow velocities. The later second effect is the recharge of infiltrated water. Rainfall events observed between 2016/12/9 and 2018/9/31, the rise of groundwater levels are 9.5 hours earlier than the increase of soil moisture at -400 cm. After the infiltrated water reach saturated zones, significant differences between groundwater inflow and outflow velocities were observed. Based on rainfall events analyzed in this study, 40 mm of accumulated rainfall is capable to induce sufficient infiltration to cause the increase of soil moisture at -400 cm and reach saturated zone subsequently. For dry events, declines of groundwater levels were earlier than decreases of soil moisture at -400 cm. It is suspected that the declines of groundwater levels were induced by the decrease of soil moisture due to reduces of near surface (i.e., above -400 cm) hydrostatic pressure. This hypothesis was supported by differences between groundwater inflow and outflow velocities were insignificant during dry events. Drying or wetting in near surface soil moisture will induce changes in groundwater levels to quickly reflect changes of near surface hydrostatic pressures caused by variations of soil moistures due to ET and RI.
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Hickman, Mosdell B. L. "The development and evaluation of analytical methods for the analysis of trace levels of moisture in high purity gas samples." Thesis, 2016. http://hdl.handle.net/10539/19356.
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A Dissertation submitted in fulfillment of the requirements for the degree
Master of Science
In the Faculty of Sciences
at the University of the Witwatersrand, Johannesburg
Johannesburg, January 2015<br>Three methods, for the analyses of low levels of moisture in gas samples,
were developed and optimized. The analytical techniques included Fourier
Transform Infrared Spectroscopy (FTIR) and Pulsed Discharge Helium
Ionization/Gas Chromatography (PDHID/GC).
The methods included the direct analyses of moisture in gas samples
using FTIR as well as the analysis of acetylene (C2H2) by FTIR and
GC/PDHID. For the latter methods, the purpose was to convert the
moisture in a gas sample to C2H2 by hydrolization of the calcium carbide
(CaC2) with moisture to C2H2 and then analyze the resulting C2H2 content
by FTIR or GC/PDHID. The C2H2 result was then converted back to
moisture to obtain the moisture content of the sample.
The FTIR moisture method developed provided eleven different
wavenumbers for quantitation providing a wide analytical scope,
specifically in complex gas matrices, where there is often peak overlap
between matrix and moisture. A heated eight meter glass long path gas
cell and a mercury cadmium telluride (MCT) detector were utilized. The
FTIR method required much greater volumes of sample than the GC
method but allowed for direct analysis of moisture without prior conversion
to acetylene. Moisture permeation standards were used for calibration and
the LOD’s ranged from 0.5 to 1 ppm with quantification possible from 0.5
to 10ppm.
For the FTIR C2H2 method various concentration ranges were established
from 50 up to 2000 ppm. Three wavenumbers were evaluated for C2H2
and methane was introduced as an internal standard. The use of methane
as an internal standard provided better r2 values on the calibration data
than for the tests run without internal standard.
A gas chromatographic (GC), pulsed discharge helium ionization detector
(PDHID) method for the determination of moisture content in small
quantities of gases, based on the conversion of the moisture to acetylene
(C2H2) prior to analysis, was developed. The method developed on the
GC/PDHID for C2H2, provided a quantitation range from 0.6 to 7.7 ppm.
Conversion of the moisture to acetylene was achieved by hydrolysing an
excess of calcium carbide (CaC2) in a closed reaction vessel with a
measured volume of a sample containing a known quantity of moisture.
The gaseous reaction mixture was transferred, using helium (He) carrier
gas, to a GC/PDHID, set up with “sample injection and heart cut to
detector” to prevent matrix disturbances on the PDHID, for analysis. The
acetylene concentration values thus obtained were converted back to
moisture values and percentage recoveries calculated. A similar
conversion process was applied on FTIR.
The conversion of moisture to C2H2 using CaC2 was tested and proven to
be viable. Quantification was not possible as the available sample holder
could not be adequately sealed to prevent air ingress. This led to higher
C2H2 values than expected. This process can be optimized by the design
and production of a sealed sample holder.
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Rahman, Mohammad Shafiqur. "Soil acidity and Eucalypt growth : aluminium toxicity and its interactions with calcium, phosphorus and moisture levels." Phd thesis, 1991. http://hdl.handle.net/1885/142602.
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Assefa, Amelework Beyene. "Genetic diversity analysis of lowland sorghum [Sorghum bicolor (L.) Moench) landraces under moisture stress conditions and breeding for drought tolerance in North Eastern Ethiopia." Thesis, 2012. http://hdl.handle.net/10413/9876.
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Sorghum [Sorghum bicolor (L.) Moench] is one of the most important cereal crops grown in arid and semi-arid regions of the world. The North Eastern regions of Ethiopia are known for its high sorghum production and genetic diversity, and proneness to moisture stress. Globally, moisture stress is one of the major sorghum production constraints limiting genetic gain through breeding. Although, the importance of Ethiopia’s sorghum germpalsm has been widely recognized both nationally and internationally, the genetic potential of the germplasm has not yet been fully assessed and exploited in breeding programmes. Therefore, the objectives of this study were: (1) to evaluate sorghum production systems and patterns, major production constraints and cropping mechanisms, varietal diversification, farmers’ criteria for choosing varieties over time and space, and adoption of improved varieties, (2) to assess the agro-morphological and molecular diversity and population structure of lowland sorghum landraces collected from different geographic origins using morphological and SSR markers, (3) to assess the performance of sorghum landraces under moisture stress conditions and identify promising lines, and (4) to determine heterosis and combining ability of lowland sorghum landraces for grain yield, yield components and drought tolerance and to identify suitable parents for future hybrid cultivar development for the North Eastern Ethiopia or similar environments.
A survey was conducted in the North Eastern Ethiopia sampling three Administrative Zones, six Districts and 12 Peasant Associations. Data was gathered from a total of 171 farmers and analyzed using SPSS statistical package. The results suggest that the performance of sorghum was generally poor mainly due to moisture stress, pests, diseases, weeds, farmland fragmentation due to demographic pressure, poor soil fertility, and poor performance of the local varieties. The productivity of sorghum was also largely hindered by the use of inherently poor yielding local landraces as farmers were forced to abandon their high yielding, big-headed and late maturing sorghum varieties due to the prevalence of recurrent moisture stress. The survey found that the region is as a rich source of genetic diversity and more than 70 distinct sorghum landraces were identified. The majority of the farmers grew their local landraces, despite the accessibility and availability of many improved sorghum varieties and production packages. Farmers were willing to adopt the improved varieties if they had farmers preferred attributes such as as red seed colour, tall with high biomass yield. To benefit the most from the available improved technologies, farmers have to be part of the breeding process right from the very beginning.
Lowland sorghum accessions which exhibited farmer-desired traits were selected from the entire landrace germplasm collection at the national gene bank of Ethiopia. Field evaluations of the selected 278 landraces together with checks were held at Sirinka and Kobo agricultural research stations for 12 qualitative and 10 quantitative traits under stress and non-stress conditions. Two hundrad landraces were selected on the basis of their morphological distinctiveness and drought tolerance, in terms of earliness and yield stability. Molecular level diversity assessment was conducted using 30 SSR markers. Considerable magnitude of variation was observed among landraces between and within geographic origin for most of the traits studied. The morphological variability was also complemented by high molecular markers diversity. Thirty two pure lines were selected for inclusion as parents in the sorghum breeding programme for yield and drought tolerance.
The selected lines were then crossed to four cytoplasmic male-sterile lines that had different cytoplasm systems (A1 to A4) using a line x tester mating design scheme. The 32 parents, together with the 128 hybrids and 4 check varieties were evaluated for grain yield, yield components traits and drought tolerance under stress and non-stress environments. Data were analysed using GenStat statistical package following a fixed effects model. Non-additive gene action was predominant in controlling plant height, grain yield, above ground biomass, grain filling duration, 100-seed weight and panicle weight, whereas additive gene action was found more important in controlling days to 50% anthesis and panicle length. Novel landraces with high GCA effects were selected including 214838-A, 242039-B, 75454, 73056-B, and 242050-A which will serve as potential parents for cultivar development. Similarly, the study identified new experimental hybrids i.e. ICSA 749 x 242039-B, ICSA 756 x 242049-B, ICSA 756 x 75454, ICSA 756 x 73059 and ICSA 756 x 214855 with high SCA effects and heterosis for grain yield which will be forwarded for further stability analysis and farmers participatory selections at representative growing environments. In general, the study identified invaluable sorghum germplasm and candidate hybrids useful for further breeding and conservation strategies.<br>Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.