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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Alterações no ciclo hidrológico e na perda de solo devido aos diferentes usos do solo e variações climáticas em área de Cerrado / Water cycle and soil loss variations due to different land uses and climate variability in a Brazilian Cerrado area

Jamil Alexandre Ayach Anache 23 November 2017 (has links)
A expansão agropecuária governa as mudanças no uso do solo no Brasil devido à alta demanda dos mercados interno e externo por alimento, fibra e energia. Entretanto, os efeitos e os processos decorrentes dessas alterações no ciclo hidrológico e na conservação do solo são pouco estudados de forma experimental em regiões de clima tropical e subtropical. No Estado de São Paulo, o uso do solo acontece de forma intensiva, as áreas de Cerrado nativo estão fragmentadas e pastagens vêm sendo substituídas por plantações de cana-de-açúcar devido à alta demanda por etanol e açúcar. Este trabalho tem como objetivo compreender as relações, trocas, variações e tendências das componentes do balanço hídrico e dos processos erosivos em potenciais mudanças no uso do solo que são encontradas no Sudeste do Brasil: de condições naturais (Cerrado sensu stricto) para pastagem, cana-de-açúcar e solo exposto. Para isso, foram monitorados, nos diferentes usos do solo, as condições meteorológicas, o escoamento superficial, a evapotranspiração, o conteúdo de água no solo, a erosão do solo e a flutuação do nível freático do aquífero. As alterações no uso do solo modificam significativamente o balanço hídrico, com aumento do escoamento superficial (pelo menos 14 mm ano-1) e diminuição da evapotranspiração (pelo menos 529 mm ano-1) quando o Cerrado sensu stricto é substituído por pastagem ou cana-de-açúcar. Entretanto, no Cerrado sensu stricto o volume de água disponível para percolação ao longo da zona não saturada e potencial recarga do aquífero tende a ser menor que em áreas agrícolas. As observações mostram que o solo exposto e a cana-de-açúcar possuem os maiores valores erosão do solo (16,00 ± 5,97 t ha-1 ano-1 e 0,64 ± 0,49 t ha-1 ano-1, respectivamente). Além disso, há semelhanças entre as taxas de perda de solo na pastagem (0,11 ± 0,04 t ha-1 ano-1) e no Cerrado sensu stricto (0,14 ± 0,06 t ha-1 ano-1). Devido às curtas séries de dados de escoamento superficial e erosão do solo, a adoção de modelos de base física como o WEPP (Water Erosion Prediction Project), é alternativa viável para simulações que considerem as variabilidades climáticas de regiões subtropicais. Projeções climáticas revelam que não ocorrerão alterações significativas nas respostas (escoamento superficial e erosão do solo) em relação ao clima base atual apesar do aumento significativo na precipitação nos cenários mais drásticos (entre 5% e 9%). Por fim, a manutenção do ciclo hidrológico e o controle da erosão do solo alcançados pelo Cerrado sensu stricto são benefícios que contrastam com a diminuição da recarga potencial do aquífero em áreas de vegetação densa. A cana-de-açúcar e a pastagem são usos do solo concorrentes e seus efeitos nos padrões hidrológicos e na erosão do solo se equilibram. / The agricultural expansion in Brazil drives land use changes due to the higher demand of internal and external markets for food, fiber and fuel. However, the effects and processes that result from these changes on hydrological cycle and soil conservation are not well explored in an experimental approach under tropical and subtropical climates. The land use is intense in the State of São Paulo, where the undisturbed woodlands in the Cerrado biome are fragmented and pasturelands are transformed in sugarcane plantations due to the higher sugar and ethanol demands. This thesis aims to comprehend the relations, trade-offs and variations of the water balance components and soil erosion processes under potential land use changes that can be found in southeastern Brazil: from natural landscapes (wooded Cerrado) to pastureland, sugarcane and bare soil. They were monitored in these different land uses: meteorological conditions, runoff, evapotranspiration, soil moisture content, soil erosion, and water table fluctuation. The land uses changes significantly influence the water balance, increasing the runoff (at least 14 mm yr-1) and decreasing evapotranspiration (at least 529 mm yr-1) when wooded Cerrado is substituted by pasture or sugarcane. Nevertheless, the soil water content available for deep percolation through the unsaturated zone and potential aquifer recharge in the wooded Cerrado tend to be smaller than in agricultural fields. Soil loss observations reveal that bare soil and sugarcane have the highest rates (16.00 ± 5.97 t ha-1 yr1 and 0.64 ± 0.49 t ha-1 yr-1, respectively). Additionally, there are similarities between the soil loss rates of pastureland (0.11 ± 0.04 t ha-1 yr-1) and wooded Cerrado (0.14 ± 0.06 t ha-1 yr-1). Due to the short-period observations of runoff and soil erosion, the use of a process-based model such as WEPP (Water Erosion Prediction Project) is a feasible alternative for simulations considering climatic variability under subtropical conditions. Projected climates reveal that in spite of significant increased rainfall (between 5% and 9%) in the most drastic scenarios, there are no significant changes on runoff and soil erosion rates in relation to the actual baseline climate. Finally, the hydrological stability and soil erosion control are benefits reached by the wooded Cerrado that contrast with the decrease in potential aquifer recharge in a dense vegetation area. Sugarcane and pasture are concurrent land uses and their effects on hydrological patterns and soil erosion are equivalent.
52

Analyse économique et simulation prospective dans la planification de la ville sobre en carbone : Application à Grenoble du modèle TRANUS+ / Economic analysis and prospective modelling to plan low carbon cities : The case of Grenoble using TRANUS+ model

Saujot, Mathieu 07 November 2013 (has links)
La planification urbaine stratégique en France se voit chargée de manière croissante des questions environnementale et climatique. Mais est-elle réellement capable d'infléchir les dynamiques d'étalement ainsi que de former un cadre efficace pour la réduction des émissions des transports ? Et que peuvent apporter l'analyse économique et la simulation prospective à la démarche de planification ? Pour y répondre nous avons replacé notre analyse de l'apport des outils économiques à la planification urbaine dans la perspective d'ensemble de réforme politique et administrative du contexte français. Cela a pris la forme d'une analyse critique de la pratique actuelle de la planification, des évolutions à l'œuvre et des conditions d'une meilleure intégration de l'analyse économique dans la démarche et les méthodes de planification. Nous avons construit et utilisé sur le cas de Grenoble, des outils d'analyse économique permettant de traiter la question des politiques climatiques locales dans la planification, d'une manière prospective et systémique. Il s'agit de la 1ère application du modèle de simulation urbanisme-transport TRANUS en France, et de son utilisation dans le cadre d'une méthodologie économique pour produire des courbes de coût d'abattement intégrant le caractère systémique de la ville pour le secteur des transports. Le modèle et la méthodologie économique qui lui est adossée constituent ce que nous appelons l'outil TRANUS+. Nous avons également réinterrogé plusieurs points à partir du cadre de la planification urbaine : la question du choix des outils de modélisation ainsi que celle des modalités du calcul économique, la question de la vulnérabilité énergétique liée à la mobilité, celle enfin du déploiement des véhicules électriques. Cela nous permet d'avoir une vision d'ensemble des apports de la planification et des voies pour la renforcer. / Strategic spatial planning in France is currently given a rising importance for environmental and climate issues. But is this tool really able to reduce urban sprawl and to produce a efficient framework for reducing transport emissions? And what can be the potential contributions to planning of economic analysis and prospective modelling? To answer this, we developed our study on the contribution of economic tools to planning into the global political and administrative reforms of France. We then produced a critical analysis of current planning practices and recent evolutions, and try to define the conditions for a better integration of economic analysis into planning processes and methods. For our case study (Grenoble urban area) we built and used economic tools able to inform local climate policies in the framework of urban planning. It is the first implementation of the land -use transport interaction model TRANUS in France, which was linked to an original economic methodology in order to produce marginal abatment cost curves useful at the urban level. This model and the methodology can take into account the systemic nature of cities and then help to define better transport policies: we call this tool TRANUS+. To have a more complete view of the urban planning question and the way to improve it, we investigated several issues from the perspective of planning: the choice of modelling tool and the role of cost-benefit analysis, energy poverty in the transport sector, electric vehicle deployement.
53

Late Pleistocene and Holocene Aged Glacial and Climatic Reconstructions in the Goat Rocks Wilderness, Washington, United States

Heard, Joshua Andrews 01 January 2012 (has links)
Eight glaciers, covering an area of 1.63 km2, reside on the northern and northeastern slopes of the Goat Rocks tallest peaks in the Cascades of central Washington. At least three glacial stands occurred downstream from these glaciers. Closest to modern glacier termini are Little Ice Age (LIA) moraines that were deposited between 1870 and 1899 AD, according to the lichenometric analysis. They are characterized by sharp, minimally eroded crests, little to no soil cover, and minimal vegetation cover. Glacier reconstructions indicate that LIA glaciers covered 8.29 km2, 76% more area than modern ice coverage. The average LIA equilibrium line altitude (ELA) of 1995 ± 70 m is ~150 m below the average modern ELA of 2149 ± 76 m. To satisfy climate conditions at the LIA ELA, the winter snow accumulation must have been 8 to 43 cm greater and mean summer temperatures 0.2 to 1.3 ºC cooler than they are now. Late Pleistocene to early Holocene (LPEH) aged moraines are located between 100 and 400 m below the LIA deposits. They have degraded moraine crests, few surface boulders, and considerable vegetation and soil cover. Volcanic ashes indicate LPEH moraines were deposited before 1480 AD while morphometric data suggest deposition during the late Pleistocene or early Holocene. The average LPEH ELA of 1904 ± 110 m is ~ 240 m and ~90 m below the modern and LIA ELAs, respectively. The climate change necessary to maintain a glacier with an ELA at that elevation for LPEH conditions requires the winter accumulation to increase by 47 to 48 cm weq and the mean summer temperature to cool by 1.4 to 1.5 ºC. Last glacial maximum (LGM) moraines are located more than 30 km downstream from modern glacial termini. They are characterized by hummocky topography, rounded moraine crests, complete vegetation cover, and well developed soil cover. Moraine morphometry, soil characteristics, and distance from modern glacial termini indicate that deposition occurred at least 15 ka BP during an expansive cooling event, the last being the LGM. The LGM ELA of 1230 m is ~920 m below the modern ELA. The climate change necessary to maintain a glacier with an ELA at that elevation for LGM conditions requires the mean summer temperature to cool by 5.6 ºC with no change in precipitation.
54

Evaluations of the Environmental Effects of Controlled Tile Drainage on Watershed and River Using the Improved SWAT and the QUAL2Kw Under Current and Future Climate Regimes

Que, Zhenyang 19 January 2022 (has links)
In agriculture-dominated areas, water pollution resulting from nutrients migrating from farms to water bodies is a major concern. The migration is further exacerbated by traditional tile drain known as Uncontrolled Tile Drainage (UCTD), which removes excess water from areas to keep the water table low enough for crops to grow. UCTD, commonly used in Ontario, Canada, is believed to contribute to water quality issues, whereas Controlled Tile Drainage (CTD) is an alternative technique in which a structure controls the outlets of the drains so that water only leaves a field when the water table level exceeds a desired threshold. Considered as a Best Management Practice (BMP), CTD has been documented as an efficient practice preventing nutrients from migrating out of agricultural fields. This thesis aims to improve our understanding of the environmental benefits of replacing UCTD with CTD. Three significant contributions were achieved. The first contribution of the thesis is the improvements of the algorithm for calculating nitrates in tile flows in the Soil and Water Assessment Tool (SWAT) model. Researchers have simulated CTD by dynamically changing tile depth to mimic the operation of outlet structure gates, but it has been demonstrated that doing so results in inaccuracies, and so the algorithm in the model has been improved subsequently. The current author proposed and tested a new algorithm for calculating nitrates in tile flows that better represents the dynamics of water and nutrients in soil layers for the SWAT model. A model for the South Nation watershed, located in Ontario, Canada, was then developed and successfully calibrated using the improved SWAT model. The second contribution was the extension of the SWAT model to simulate riverine hydraulic and water quality processes by coupling it with the QUAL2Kw model. In this thesis, a procedure is developed to couple the SWAT model and the QUAL2Kw model to enable continuous simulations of 13 water quality parameters in the South Nation River system. The coupled model was calibrated and verified at various observed locations along the river during the five seasons of growth from 2006 to 2010. The simulation results suggested that CTD also improved the water quality of the river by lowering biologically available N levels of NO2--N, and NO3--N, thereby impeding phytoplankton growth in the river. The third contribution is the verification of the benefits of replacing UCTD with CTD in the future climates. The confirmation was done using the SWAT model alone, and then the coupled SWAT/QUAL2K models, using a matrix of climate change experiments performed with several Global Climate Models and Regional Climate Models. The results suggest that nutrient loading from the watershed will increase in the 2021–2050 period compared to the 1985–2006 period. Thus, pollution from agricultural fields will worsen with the current UCTD approach, while the results also show that CTD would perform effectively and stably in future climate scenarios and could counterbalance the effects of climate change on water quality. To the author’s knowledge, this study is the first attempt to date to assess the environmental effects of CTD on a watershed and river by coupling the SWAT and QUAL2Kw models. The findings expand the current scope of knowledge on the environmental effects of CTD on watersheds and rivers under current and future climate change regimes. Long periods of continuous simulation and a matrix of climate change scenarios also make this study stand out from other studies. It laid a foundation for future investigations.
55

Tränarbeteenden, motivationsklimat och psykologiskt välbefinnande : En kvantitativ tvärsnittsstudie på ungdomsfotbollsspelare

Fromell, Lukas January 2023 (has links)
Föreliggande tvärsnittsstudie är av kvantitativ design med syftet att undersöka hur olika typer av tränarbeteenden och olika typer av motivationsklimat påverkar psykologiskt välbefinnande hos ungdomsfotbollsspelare, samt hur väl de olika typerna av tränarbeteenden och motivationsklimat predicerar ungdomsfotbollspelares psykologiska välbefinnande. Den aktuella studien hade 95 deltagare i åldrarna 16 till 19 år (M= 16.97, SD= 2.6). Deltagarna självskattade sina upplevelser av tränarbeteenden, motivationsklimat och psykologiskt välbefinnande utifrån frågeformulären Coaching Behavior Scale for Sport, Perceived Motivational Climate in Sport Questionnaire-2 och Ryff's Psychological Well-Being scales. Resultatet av en enkel regressionsanalys visade att tränarbeteendet tävling/-matchstrategi hade störst positiv effekt på psykologiskt välbefinnande. Vidare visade analysen att tränarbeteendet negativ personlig kontakt hade en negativ effekt på psykologiskt välbefinnande. Den enkla regressionsanalysen visade även på en positiv effekt på psykologiskt välbefinnande av uppgiftsorienterat motivationsklimat, och en negativ effekt på psykologiskt välbefinnande av resultatorienterat motivationsklimat. Studiens resultat anses kunna användas för att facilitera psykologiskt välbefinnande för ungdomsfotbollspelare genom lämpliga tränarbeteenden och uppgiftsorienterade motivationsklimat / This cross-sectional study is based on a quantitative method with the aim to investigate how different types of coaching behaviors and motivational climates affect psychological well-being in young football players, and how well the different types of coaching behaviors and motivational climates predict young football players’ psychological wellbeing. The current study had 95 participants aged 16 to 19 years (M=16.97, SD=2.6). The participants self-rated their experiences of coaching behaviors, motivational climate and psychological well-being based on the Coaching Behavior Scale for Sport, Perceived Motivational Climate in Sport Questionnaire-2 and Ryff's Psychological Well-Being scales. The results of a simple regression analysis showed that the coaching behavior competition/match strategy had the greatest positive effect on psychological well-being. Furthermore, the analysis showed that the coaching behavior negative personal contact had a negative effect on psychological well-being. The simple regression analysis also showed a positive effect on psychological well-being of task-oriented motivational climate, and a negative effect on psychological well-being of results-oriented motivational climate. The results of the study are considered to be used to facilitate psychological well-being of youth football players through appropriate coaching behaviors and task-oriented motivational climates.
56

The impact of glaciation and climate change on biogeochemical cycling and landscape development

Mabry, James Brice 19 March 2012 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Lake cores from Dry Lake, California and Crystal Lake, Illinois were analyzed to identify climate variability and characterize landscape response to glacial/deglacial climate transitions. Geochemical analysis of the Dry Lake sediment prior to the 8.2 kyr event revealed average values for percent total organic carbon to be 4% with a range of 0.2% to 15.2%. The average decreased to approximately 2.1% with a range of 0.4% to 5.3% during and after the event. Occluded phosphorus averaged 488 µg/g before the 8.2 kyr event and 547 µg/g after but was much lower during the event at 287 µg/g. These results were interpreted as an environment which began as warm, wet, and productive then quickly turned colder and drier during the 8.2 kyr event which resulted in a resetting of soil development. The higher temperatures returned after the 8.2 kyr event which allowed for continued soil development despite its drier climate. Previous research corroborated these conclusions. The Crystal Lake geochemical record was very different from Dry Lake. Percent total organic carbon averaged 6.7% with a range of 3.9% to 8.5% during the Younger Dryas but recorded a lower average before and after at 4.9% and 4.6% respectively. Occluded phosphorus acted similarly with a higher average during the cooling event, 2626 µg/g, and lower averages before and after, 1404 µg/g and 1461 µg/g, respectively. This was interpreted as continued productivity and soil development through the cold period which was attributed to a change in biomass.
57

Felkällor och systematiska avvikelser i kvalitetsuppföljningen av tidnings- och journalpapper / Sources of error and systematic deviation in following up of quality in news- and journal paper

Bergendahl, Rikard January 2008 (has links)
<p>I papperstillverkning ställs det krav inte bara på kvalité och kvantitet utan också att stickprov från produktion utförs och tas hand om på ett korrekt sätt. Från det att ett stickprov tas ut och undersöks på brukets laboratorium kan en del källor till förändringar på provresultatet uppstå. Sådana förändringar kan uppstå för det första vid hanteringen av stickprov från pappersmaskin och provens transportering till laboratoriet och för det andra vid laboratoriets hantering och uppföljning av kvalitén. En annan faktor som kan påverka stickproven är klimatet. Årstiderna vår och höst är de tider som proverna kan påverkas mest. Prover undersöks med jämna mellanrum från färdigt papper och används till kalibrering av on-line mätning på pappersmaskin. Vissa av provresultaten skickas direkt till kunden i form av ett analyscertifikat.</p><p>I detta examensarbete var syftet att analysera vissa felkällor i provhanteringen och vad klimatet hade för påverkan på provresultatet. Det undersöktes hur varierande klimatförhållanden på pappersmaskin kunde påverka provresultaten för prov som undersöktes direkt på laboratoriet. Resultat från de proven har sen jämförts med prov som konditionerades en tid på laboratoriet i ett fast klimat (23°C, 50 % RH). Prov konditionerades både efter att provet tagits ut direkt och efter att provet hade legat uppe i maskinhallen under en längre tid. I arbetet ingick det att årstider skulle simuleras och det utfördes på Stora Enso Research Center i Falun i ett speciellt klimatrum. Klimaten som papper undersöktes i då var extremt torrt och extremt fuktigt och dessa resultat jämfördes med resultat från normalt provtagningsklimat.</p><p>Papperskvalitéerna som undersöktes var 45 g/m2 standard tidningspapper från PM 11 och 52 g/m2 SC-papper (obestruket journalpapper) från Kvarnsvedens nya maskin PM 12. Det som undersöktes var de kritiska parametrarna där det föreligger risk för att papper måste kasseras. De kritiska egenskaperna som har kassaktionsgräns är ytvikt, ljushet, nyans och i även vissa fall ytråhet och rivstyrka.</p><p>Resultaten visade att vid extrema klimatförhållanden från undersökningen på Stora Enso Research Center hade många prover påverkats till den grad att de hade lett till kassaktion. För SC-papper var ytråheten den egenskap som var mest kritisk vid extremt torrt klimat och vid fuktigt klimat var ytvikt den mest känsliga egenskapen. För standard tidningspapper var ytvikt och rivstyrka de egenskaper som påverkades mest av extremt klimat och pappret hade fått kasseras vid både extremt torrt och fuktigt klimat.</p><p>Vid undersökningen på Kvarnsveden visade resultaten att fukthalten i pappret påverkades mer än vad papprets övriga egenskaper gjorde. Förändringarna i papprets övriga egenskaper var endast marginella och höll sig inom respektive gränsvärde för kassaktion. Nyans och de andra optiska egenskaperna hade marginella förändringar för både varierande och extrema klimatförhållanden och förändringarna kan i de flesta fall anses försumbara för produktionen.</p><p>I de fall där det råder extrema klimatförhållanden som det kan göra vid vissa årstider är det mycket viktigt att operatörens hantering av stickprov sker på ett korrekt sätt. Då gäller det att stickproverna skickas ner till laboratoriet så snabbt som möjligt där påverkan är mindre än vad den kan vara inne i maskinhallen.</p> / <p>In paper production demands are set not only on quality and quantity, but it is also required that samples from the production are taken out and handled in a correct way. From the moment when a sample is taken out and up to the point when it is examined in the laboratory of the mill, a number of factors may affect the sample and thus the test result. Such changes can arise from the handling of samples from the paper machine and the transport of the samples to the laboratory and also from the handling of the samples in the laboratory. Another factor that can influence the samples is the climate and the seasons spring and autumn is the times when the samples are influenced most. Samples are examined with even intervals from finished papers and is used for calibration of on-line measurement on the paper machine and some of the sample results are sent directly to the costumer in the form of an analysis certificate.</p><p>The purpose of this project was to analyze certain error sources in the sample handling and the impact of the climate on the sample result. It was examined how varying climates on the paper machine could influence the sample results for samples that were examined directly and compared with samples that were conditioned for one hour on the laboratory in a permanent climate (23°C, 50% RH). Samples that were conditioned were either taken directly to the lab or left by the paper machine for an extended period of time. In the work, it was included that seasons would be simulated and it was carried out on Stora Enso Research centre in Falun in a climate room. The climates that papers were examined in then were extreme dry and extreme damp and these results were compared with results from normal climate for testing paper.</p><p>The paper qualities that were examined where 45 g/m2 standard newspaper from papermachine 11 and 52 g/m2 SC-paper (uncoated journal papers) from the new papermachine 12 in Kvarnsveden. What were examined were the critical parameters were it exists risk to rejection of papers. The critical properties that have a limit when the papers are rejected are grammage, ISO-brightness and nuance and in certain cases also roughness and tear strength.</p><p>The results showed that at extreme climate relations from the studies on Stora Enso Research centre samples had been influenced to that degree that many of the samples had to be rejected. For SC-paper roughness was the property that was most critical at extremely dry climate and at damp climate the grammage was the most sensitive property. Standard newspaper was very sensitive at both extremely damp and dry climates for grammage and tearing strength.</p><p>The study on Kvarnsveden showed that the moisture content in the paper was influenced more than the other properties but its changes were only marginal and within the respective limit for rejection. Nuance and the other optic properties had only marginal changes for both varying and extreme climates and the changes can in most cases be considered negligible for the production.</p><p>In those cases when there are extreme climates, like during certain seasons, it is very important that the operator handles the samples correctly. Then, it is important that the samples are sent down to the laboratory as fast as possible where the impact is smaller than if the samples stay in the machine room.</p>
58

Felkällor och systematiska avvikelser i kvalitetsuppföljningen av tidnings- och journalpapper / Sources of error and systematic deviation in following up of quality in news- and journal paper

Bergendahl, Rikard January 2008 (has links)
I papperstillverkning ställs det krav inte bara på kvalité och kvantitet utan också att stickprov från produktion utförs och tas hand om på ett korrekt sätt. Från det att ett stickprov tas ut och undersöks på brukets laboratorium kan en del källor till förändringar på provresultatet uppstå. Sådana förändringar kan uppstå för det första vid hanteringen av stickprov från pappersmaskin och provens transportering till laboratoriet och för det andra vid laboratoriets hantering och uppföljning av kvalitén. En annan faktor som kan påverka stickproven är klimatet. Årstiderna vår och höst är de tider som proverna kan påverkas mest. Prover undersöks med jämna mellanrum från färdigt papper och används till kalibrering av on-line mätning på pappersmaskin. Vissa av provresultaten skickas direkt till kunden i form av ett analyscertifikat. I detta examensarbete var syftet att analysera vissa felkällor i provhanteringen och vad klimatet hade för påverkan på provresultatet. Det undersöktes hur varierande klimatförhållanden på pappersmaskin kunde påverka provresultaten för prov som undersöktes direkt på laboratoriet. Resultat från de proven har sen jämförts med prov som konditionerades en tid på laboratoriet i ett fast klimat (23°C, 50 % RH). Prov konditionerades både efter att provet tagits ut direkt och efter att provet hade legat uppe i maskinhallen under en längre tid. I arbetet ingick det att årstider skulle simuleras och det utfördes på Stora Enso Research Center i Falun i ett speciellt klimatrum. Klimaten som papper undersöktes i då var extremt torrt och extremt fuktigt och dessa resultat jämfördes med resultat från normalt provtagningsklimat. Papperskvalitéerna som undersöktes var 45 g/m2 standard tidningspapper från PM 11 och 52 g/m2 SC-papper (obestruket journalpapper) från Kvarnsvedens nya maskin PM 12. Det som undersöktes var de kritiska parametrarna där det föreligger risk för att papper måste kasseras. De kritiska egenskaperna som har kassaktionsgräns är ytvikt, ljushet, nyans och i även vissa fall ytråhet och rivstyrka. Resultaten visade att vid extrema klimatförhållanden från undersökningen på Stora Enso Research Center hade många prover påverkats till den grad att de hade lett till kassaktion. För SC-papper var ytråheten den egenskap som var mest kritisk vid extremt torrt klimat och vid fuktigt klimat var ytvikt den mest känsliga egenskapen. För standard tidningspapper var ytvikt och rivstyrka de egenskaper som påverkades mest av extremt klimat och pappret hade fått kasseras vid både extremt torrt och fuktigt klimat. Vid undersökningen på Kvarnsveden visade resultaten att fukthalten i pappret påverkades mer än vad papprets övriga egenskaper gjorde. Förändringarna i papprets övriga egenskaper var endast marginella och höll sig inom respektive gränsvärde för kassaktion. Nyans och de andra optiska egenskaperna hade marginella förändringar för både varierande och extrema klimatförhållanden och förändringarna kan i de flesta fall anses försumbara för produktionen. I de fall där det råder extrema klimatförhållanden som det kan göra vid vissa årstider är det mycket viktigt att operatörens hantering av stickprov sker på ett korrekt sätt. Då gäller det att stickproverna skickas ner till laboratoriet så snabbt som möjligt där påverkan är mindre än vad den kan vara inne i maskinhallen. / In paper production demands are set not only on quality and quantity, but it is also required that samples from the production are taken out and handled in a correct way. From the moment when a sample is taken out and up to the point when it is examined in the laboratory of the mill, a number of factors may affect the sample and thus the test result. Such changes can arise from the handling of samples from the paper machine and the transport of the samples to the laboratory and also from the handling of the samples in the laboratory. Another factor that can influence the samples is the climate and the seasons spring and autumn is the times when the samples are influenced most. Samples are examined with even intervals from finished papers and is used for calibration of on-line measurement on the paper machine and some of the sample results are sent directly to the costumer in the form of an analysis certificate. The purpose of this project was to analyze certain error sources in the sample handling and the impact of the climate on the sample result. It was examined how varying climates on the paper machine could influence the sample results for samples that were examined directly and compared with samples that were conditioned for one hour on the laboratory in a permanent climate (23°C, 50% RH). Samples that were conditioned were either taken directly to the lab or left by the paper machine for an extended period of time. In the work, it was included that seasons would be simulated and it was carried out on Stora Enso Research centre in Falun in a climate room. The climates that papers were examined in then were extreme dry and extreme damp and these results were compared with results from normal climate for testing paper. The paper qualities that were examined where 45 g/m2 standard newspaper from papermachine 11 and 52 g/m2 SC-paper (uncoated journal papers) from the new papermachine 12 in Kvarnsveden. What were examined were the critical parameters were it exists risk to rejection of papers. The critical properties that have a limit when the papers are rejected are grammage, ISO-brightness and nuance and in certain cases also roughness and tear strength. The results showed that at extreme climate relations from the studies on Stora Enso Research centre samples had been influenced to that degree that many of the samples had to be rejected. For SC-paper roughness was the property that was most critical at extremely dry climate and at damp climate the grammage was the most sensitive property. Standard newspaper was very sensitive at both extremely damp and dry climates for grammage and tearing strength. The study on Kvarnsveden showed that the moisture content in the paper was influenced more than the other properties but its changes were only marginal and within the respective limit for rejection. Nuance and the other optic properties had only marginal changes for both varying and extreme climates and the changes can in most cases be considered negligible for the production. In those cases when there are extreme climates, like during certain seasons, it is very important that the operator handles the samples correctly. Then, it is important that the samples are sent down to the laboratory as fast as possible where the impact is smaller than if the samples stay in the machine room.
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The role of personality and organisational climate in employee turnover

Masoga, Liziwe 04 April 2013 (has links)
Text in English / Research on employee turnover dates back many decades. However, this research traditionally focused on either understanding turnover intentions or the factors preceding turnover, such as job satisfaction. Despite the challenge in SA being huge and organisations struggling to keep their talent, the research on employee turnover is quite limited. Understanding the different variables that influence employee turnover and providing practical solutions on how to mitigate turnover would be valuable to many organisations. The aim of this research project was to understand the role of personality and organisational climate in employee turnover. In addition, a comprehensive model of employee turnover was developed and tested. The Five Factor Model was used to conceptualise personality, while (due to the limited nature of existing models) a new model was designed to conceptualise organisational climate. A sample of 1 536 people was drawn from a large retail organisation in SA, with 807 stayers and 729 leavers. Biographical, personality and organisational climate information was collected over a two-year period for both samples. Results of the study were mixed; there were no significant differences in the two samples regarding the big five personality factors, except when nine bipolar scales were used. On these scales, leavers were found to be more assertive, persuasive and optimistic than stayers. All five personality factors moderated HR policies & procedures in determining turnover. There were differences between the stayers and leavers samples with regard to age, gender, tenure and absenteeism. Organisational climate was a key determinant of whether people left or stayed and organisations had more than one climate. Personality, organisational climate and absenteeism accounted for 29% of turnover. The proposed model of employee turnover met most of the requirements of goof fit measures when using Structural Equation Modelling (SEM). / Psychology / D.Litt. et Phil.
60

Recharging the Ogallala Formation Using Shallow Holes

Dvoracek, M. J., Peterson, S. H. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / The southern bed of the ogallala aquifer is hydrologically isolated from all outside areas of recharge, requiring local precipitation for all natural recharge. Current withdrawals are so much greater than natural recharge that it appears that artificial recharge affords the only means of establishing at least a pseudo-balance. A number of observation wells were drilled at Texas Tech University, and subsequently capped until recharge water became available. The initial recharge was 2.5 af over 12 days, at a rate of 120 gpm for about the first day, after which 60 gpm was relatively constant. Approximately 1 month later, 1.2 af were recharged over 3 days at rates ranging over 140-90 gpm. It became evident that a cavity was present at the bottom of the hole being recharged. On a later recharge occasion, the cavity seemed to have enlarged. During a period of 2 years more than 28 af of surface runoff water have been recharged through the shallow hole with increases in recharge rates for each subsequent recharge period. The nature of this phenomenon and the cavities are not understood. This may represent the long sought after answer to recharge of the aquifer, but much more extensive research needs to be done.

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