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Evolution of stratospheric ozone in the mid-latitudes in connection with the abundances of halogen compoundsGopalapillai, Prijitha 09 March 2012 (has links) (PDF)
Cette thèse a pour objet l'étude de l'évolution à long terme de l'ozone stratosphérique, en liaison avec la variation de l'abondance des composés halogénés dans la moyenne atmosphère. Dans ce but, les longues séries de mesures sol et satellitaires de la distribution verticale d'ozone obtenues depuis les années 1980 sont évaluées dans six stations du Network for the Detection of Atmospheric Composition Changes (NDACC - réseau international de surveillance de la composition atmosphérique), pour déterminer les biais et dérives éventuelles entre les mesures. Les tendances d'ozone stratosphérique sont ensuite évaluées dans deux stations de moyenne latitude de l'hémisphère nord à l'aide d'un modèle statistique utilisant deux types d'indicateurs pour représenter l'évolution des substances destructrices d'ozone dans la stratosphère: (1) l'Equivalent Effective Stratospheric Chlorine (EESC - paramètre quantifiant l'effet des composés chlorés et bromés stratosphériques sur l'ozone) et (2) deux fonctions linéaires avec changement de pente en 1997. L'étude de tendance est effectuée pour les mesures du contenu intégré d'ozone dans les deux stations et les mesures de distribution verticale à l'Observatoire de Haute-Provence. L'étude utilise les mesures sol d'ozone obtenues par lidar (profil d'ozone), spectromètre Dobson (contenu intégré et profil d'ozone par la méthode Umkehr), ozonosondage (profil d'ozone) et spectromètre UV-Visible SAOZ (contenu intégré). Les observations satellitaires utilisées proviennent des instruments SBUV(/2), SAGE II, HALOE, UARS MLS, Aura MLS et GOMOS. Tout d'abord une étude de la sensibilité des mesures lidar aux sections efficaces d'ozone utilisées dans l'algorithme de restitution est effectuée. La différence relative d'ozone obtenue à partir des mesures restituées à l'aide de différents jeux de données de section efficace reconnues par les instances internationales, est inférieure à ±1% entre 10 et 35 km à toutes les latitudes (à l'exception de -1.5 % à 15 km aux tropiques). Au-dessus de 35 km, l'écart s'accroit, avec un maximum à 45 km de 1.7 % aux tropiques et un minimum de 1.4 % aux hautes latitudes. La stabilité des différentes séries de mesures satellitaires et sol de la distribution verticale d'ozone est ensuite évaluée à partir de la comparaison avec les mesures lidar dans les six stations NDACC considérées au cours de la thèse. Le meilleur accord (±3%) entre les mesures issues des différentes techniques et les mesures lidar est obtenu entre 20 et 40 km. Dans ce domaine d'altitude, la dérive entre les différentes mesures est inférieure à ±0.3%yr−1. Des dérives et des biais comparativement plus importants sont calculés en dessous de 20 km et au-dessus de 40 km. Par ailleurs, la stabilité à plus long terme des mesures d'ozone est étudiée à partir de séries temporelles combinant les différences relatives entre les mesures lidar et les mesures SAGE II et HALOE d'une part avec les différences relatives entre les mesures lidar et les les mesures Aura MLS d'autre part. Les dérives estimées à partir de ces séries composites couvrant 27 années de mesure sont très faibles, de l'ordre de ±0.2%yr−1. Enfin les tendances évolutives du contenu intégré d'ozone sont évaluées à l'Observatoire Météorologique de Hohenpeissenberg (MOHp - Allemagne) à partir des mesures du spectromètre Dobson et à l'Observatoire de Haute-Provence (OHP - France) à partir des mesures des spectromètres Dobson et SAOZ. A l'OHP, les tendances de la distribution verticale d'ozone sont calculées à partir des mesures obtenues par différentes techniques de mesures, sol et satellitaires. Pour ce faire, un modèle de régression multilinéaire est développé, fondé sur l'utilisation de différentes variables telles que l'oscillation quasi-biennale (QBO), l'oscillation Nord-Atlantique (NAO), le flux solaire, le flux de chaleur turbulent, l'épaisseur optique des aérosols stratosphériques et les tendances à long terme. L'estimation des tendances calculées à partir des mesures de contenu intégré d'ozone dans les deux stations fournit des valeurs significatives, de l'ordre de −1.4±0.29 DUyr−1) et 0.55±0.29 DUyr−1 respectivement avant et après 1997. Les valeurs positives de la tendance après 1997, significatives pour un intervalle de confiance de 95 %, montrent clairement un début de rétablissement de l'ozone stratosphérique à ces latitudes. Concernant la distribution verticale d'ozone, les tendances calculées à partir de la moyenne des différentes séries de données à l'OHP montrent des valeurs maximales en valeur absolue de l'ordre de −0.5±0.1 %yr−1 entre 16 et 22 km et de −0.8±0.2 %yr−1 entre 38 et 45 km avant 1997. Des tendances positives significatives (0.2±0.05-0.3±0.1 %yr−1) sont évaluées entre 15 et 45 km après 1996. Ces tendances significatives du profil vertical d'ozone avant et après 1997 corroborent les résultats obtenus à partir du contenu intégré d'ozone et confirment le début de rétablissement de l'ozone stratosphérique. Par ailleurs, dans les deux cas (contenu intégré d'ozone et distribution verticale), les tendances post-1997 restituées par le modèle utilisant les fonctions linéaires sont plus élevées que celles issues du modèle utilisant l'EESC, indiquant ainsi que d'autres paramètres contribuent à l'augmentation du contenu en ozone. Enfin, il a été constaté que les contenus intégrés élevés d'ozone observés ces dernières années étaient liés à l'influence de la QBO et des processus dynamiques. Ainsi la QBO, la NAO et le flux de chaleur turbulent expliquent environ 80 % de l'importante anomalie positive de 25 - 30 DU mesurée entre février et avril 2010.
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A case study of the distribution of high wind speeds in the Greater Victoria area using wind data from the School-Based Weather Station NetworkMatsuda, Miho 30 April 2014 (has links)
This thesis presents the distribution of strong wind and wind pressure in the Greater Victoria area associated with winter mid-latitude cyclones based on climate data from the School-Based Weather Station Network during 6 selected days in the winters of 2006, 2007 and 2008. The objectives of this study are i) to test whether synoptic conditions favourable to severe mid-latitude cyclonic storms that are well described in the literature were associated with the selected storms, ii) to determine the time patterns of high wind speed and its direction and maximum gusts, iii) to test necessity of considering the spatial variation in air density and its controls in general assessments of the spatial variation in wind pressure and wind damage potential in the local area, iv) to identify potential areas susceptible to wind damage. Observations taken every second were from Davis Vantage Pro2 TM Plus weather stations located on the southern edge of school building roofs. Thirty-minute means and gust wind speeds were used. All six storms went north of Victoria. The synoptic conditions associated with the selected mid-latitude cyclones agreed with the ones described in literature. Strongest winds at most stations were generally from the southwest, and multiple wind speed peaks were found. The daily
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maximum gust wind speeds were found before and/or after the highest mean wind speed peak. The spatial variation in air density and its controls were found to be negligible. Although there are a number of interacting causes of the distribution, strongest winds were at stations with smooth surrounding surfaces, close to the southern shoreline, on exposed slopes and/or near relief constrictions. The area with greatest wind speeds and damage potential was found from the east of downtown extending to Lansdowne Middle School. This study provides new knowledge of winds in the Greater Victoria area and contributes to people’s better response to wind storms, land use planning and forecasting severe windstorms. / Graduate / 0368 / mmatsuda@uvic.ca
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A case study of the distribution of high wind speeds in the Greater Victoria area using wind data from the School-Based Weather Station NetworkMatsuda, Miho 30 April 2014 (has links)
This thesis presents the distribution of strong wind and wind pressure in the Greater Victoria area associated with winter mid-latitude cyclones based on climate data from the School-Based Weather Station Network during 6 selected days in the winters of 2006, 2007 and 2008. The objectives of this study are i) to test whether synoptic conditions favourable to severe mid-latitude cyclonic storms that are well described in the literature were associated with the selected storms, ii) to determine the time patterns of high wind speed and its direction and maximum gusts, iii) to test necessity of considering the spatial variation in air density and its controls in general assessments of the spatial variation in wind pressure and wind damage potential in the local area, iv) to identify potential areas susceptible to wind damage. Observations taken every second were from Davis Vantage Pro2 TM Plus weather stations located on the southern edge of school building roofs. Thirty-minute means and gust wind speeds were used. All six storms went north of Victoria. The synoptic conditions associated with the selected mid-latitude cyclones agreed with the ones described in literature. Strongest winds at most stations were generally from the southwest, and multiple wind speed peaks were found. The daily
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maximum gust wind speeds were found before and/or after the highest mean wind speed peak. The spatial variation in air density and its controls were found to be negligible. Although there are a number of interacting causes of the distribution, strongest winds were at stations with smooth surrounding surfaces, close to the southern shoreline, on exposed slopes and/or near relief constrictions. The area with greatest wind speeds and damage potential was found from the east of downtown extending to Lansdowne Middle School. This study provides new knowledge of winds in the Greater Victoria area and contributes to people’s better response to wind storms, land use planning and forecasting severe windstorms. / Graduate / 0368 / mmatsuda@uvic.ca
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The impact of the radiation balance on snowmelt in a sparse deciduous birch forestTurton, Rachael Heather January 2017 (has links)
The representation of high-latitude surface processes and quantifying surface-climate feedbacks are some of the most serious shortcomings of present day Arctic land surface modelling. The energy balance of seasonally snow-covered sparse deciduous forests at high latitudes is poorly understood and inaccurately represented within hydrological and climate models. Snow cover plays an important role in wintertime fluxes of energy, water and carbon, controlling the length of the active growing season and hence the overall carbon balance of Arctic ecosystems. Snow cover is non-uniform and spatially variable, as wind redistributes snow from areas of exposed open tundra to sheltered areas within the forest, where a deeper snowpack develops. Low solar zenith angles, coupled with sparse deciduous leafless trees, cast shadows across the snow surface. The spatial distribution of canopy gaps determines the timing of direct radiation which penetrates down through the canopy to the snow surface. The forest canopy also excludes incoming longwave radiation and yet also emits longwave radiation to the snow surface. Consequently the forest canopy plays a key role in the radiation balance of sparse forests. To improve our knowledge of these complex processes, meteorological and field observations were taken in an area of highly heterogeneous birch Betula pubescens ssp. czerepanovii forest in Abisko, Sweden during the spring of 2008 and 2009. Detailed measurements of short and longwave radiation above and below the canopy, hemispherical photographs, tree temperatures and snow surveys were conducted to quantify the radiation balance of the sparse deciduous forest. An array of below canopy pyranometers found the mean canopy transmissivity to be 74 % in 2008 and 76 % in 2009. Hemispherical photographs taken at the pyranometer locations analysed with Gap Light Analyzer (GLA) showed reasonable agreement with a mean canopy transmissivity of 75 % in 2008 and 74 % in 2009. The canopy transmissivity was found to be independent of the diffuse fraction of radiation as the canopy is very sparse. A series of survey grids and transects were established to scale up from the below canopy pyranometers to the landscape scale. Hemispherical photographs analysed with GLA showed the sparse forest canopy had a mean transmissivity of 78 % and a mean LAI of 0.25, whereas the open tundra had a mean transmissivity of 97 % and a mean LAI of < 0.01. Snow surveys showed the sparse forest snow depth to vary between 0.34 and 0.55 m, whereas the snow depth in the open tundra varied between 0.12 and 0.18 m. Observations of canopy temperatures showed a strong influence of incident shortwave radiation warming the tree branches to temperatures up to 15 °C warmer than ambient air temperature on the south facing sides of the trees, and up to 6 °C on the north facing sides of the trees. To reproduce the observed radiation balance, two canopy models (Homogenous and Clumped) were developed. The Homogeneous canopy model assumes a single tree tile with a uniform sparse canopy. The Clumped canopy model assumes a tree and a grass tile, where the tree tile is permanently in shade from the canopy and the grass tile receives all the incoming radiation. These canopy models identified the need for a parameter that accounts for the spatial and temporal variation of the shaded gaps within the sparse forest. JULES (Joint UK Land Environment Simulator) is the community land surface model used in the UK Hadley Centre GCM suite. Modifications of the land-surface interactions were included in JULES to represent the shaded gaps within the sparse deciduous forest. New parameterisations were developed for the time-varying sunlit fractions of the gap (flit), the sky-view fraction (fv), and the longwave radiation emitted from the canopy (LWtree). These model developments were informed by field observations of the forest canopy and evaluated against the below canopy short and longwave radiation observed data sets. The JULES Shaded gap model output showed a strong positive relationship with the observations of below canopy shortwave and longwave radiation. The JULES Shaded gap model improves the ratio of observed to modelled short and longwave radiation on sunny days compared to the JULES model. The JULES Shaded gap model reduces the time to snow melt by 2 to 4 days compared to the JULES model, making the model output more aligned with in-situ observational data. This shortening of the modelled snow-season directly impacts on the simulated carbon and water balance regionally and has wider relevance at the pan-Arctic scale. When JULES Shaded Gap was evaluated on the global scale, it improved the modelled snowmass across large areas of sparse forest in northern Canada, Scandinavia and Northern Russia with respect to GlobSnow. The performance of the land surface-snow-vegetation interactions of JULES was improved by using the Shaded gap to model the radiation balance of sparse forests in climate-sensitive Arctic regions. Furthermore these observational data can be used to develop and evaluate high latitude land-surface processes and biogeochemical feedbacks in other earth system models.
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“Man är rätt så utelämnad till sig själv som enhetschef, det gäller att vara lite påhittig" : -En kvalitativ studie om enhetschefers handlingsutrymme i arbetet med sjukskrivningar inom offentlig äldreomsorg / ” You are in a surrendered position as a unit manager, you have to be a little bit inventive” : A qualitative study of the unit manager’s latitude in the work of sick leave in public elderlyAndersson, My, Lindkvist, Katarina January 2018 (has links)
Syftet med studien är att undersöka hur enhetschefer arbetar med sjukskrivningar på grund av arbetsrelaterad psykisk ohälsa inom offentlig äldreomsorg. Utifrån syftet har fyra frågeställningar bearbetats fram för att utveckla och öka förståelsen till studiens problemområde. Studiens metodval är kvalitativa intervjuer med en hermeneutisk ansats och tematisk analys som bearbetningsmetod. De kvalitativa intervjuerna gjordes med nio stycken enhetschefer från två olika kommuner i södra Sverige. Resultatet visade att enhetschefer har handlingsutrymme att arbeta förebyggande för att reducera sjukskrivningar och att det skiljde sig åt från hur rehabilitering hanteras. Enhetschefer inom äldreomsorgen har tydliga riktlinjer när det handlar om rehabilitering medan det förebyggande arbetet inte har det. Det finns därmed handlingsutrymme för att arbeta mer förebyggande för att reducera sjukskrivningar. Alla respondenter hade förståelse om att det förebyggande arbetet är en viktig faktor för att sjukskrivningar ska reduceras men att tid och antal medarbetare kan försvåra att det förebyggande arbetet prioriteras. Nyckelord: / The purpose of the study is to investigate how unit managers work with sick leave due to work-related mental health in public elderly care. Based on the aim, four issues have been worked out to develop and increase understanding of the study's problem area. The methodology of the study is qualitative interviews with a hermeneutic approach and thematic analysis as a method of processing. The qualitative interviews were conducted with nine unit managers from two different municipalities in southern Sweden. The results showed that unit managers have latitude to work preventively to reduce sick leave and that differs from how rehabilitation is handled. Unit managers in elderly care have clear guidelines when it comes to rehabilitation while preventive work does not have it. Therefor, unit manager have latitude for working more prevention to reduce sick leave. All respondents understood that preventive work is an important factor in reducing sick leave, but that time and number of employees can make it difficult for preventive work to be prioritized.
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Impact des évènements solaires sur l'ionisation de l'ionosphère des moyennes et basses latitudes dans le secteur Europe-Afrique / Impact of solar event in ionization of ionosphere at middle and low latitudes in the Europe-African sectorAzzouzi, Ilyasse 24 September 2016 (has links)
Ce travail a pour objet d’étudier les variations régulières de l’ionosphère aux moyennes et basses latitudes ainsi que l’impact de différents événements solaires sur l’ionisation. Pour quantifier ces variations, nous utiliserons les réseaux GPS qui permettent de mesurer le Contenu Total Electronique (TEC).Ce travail s’inscrit dans le cadre du projet ISWI. L’étude comprendra une analyse morphologique sur les variations régulières de l’ionisation en période de soleil calme (variation diurne, saisonnière et en fonction du cycle solaire) par le traitement de stations GPS en Europe et en Afrique sur la période analysée (2000 à 2014);les variations perturbées de l’ionosphère associées à des événements solaires retenus selon une grille de critères; L’analyse de l’indice ROTI afin d’étudier les scintillations ionosphériques génératrices d’une dégradation du positionnement aux basses latitudes et en particulier en Afrique.L’étude se poursuivra par la comparaison avec les modèles existants afin d’identifier leurs performances:le modèle NeQuick2, logiciel de modélisation du profil vertical médian l’ionosphère,Le modèle IONEX/CODG qui est une cartographie journalière du TEC en des positions spatiales et temporelles particulières et issu du post-traitement des mesures GPS sur une couverture mondiale.Le troisième volet de cette étude sera de donner des perspectives pour une éventuelle prévision de l’impact d'événements solaires particuliers sur l’ionosphère, par exemple la modélisation des gradients en période magnétiquement perturbée et la prévision de la présence du phénomène de scintillation ionosphérique sur certains trajets satellite-sol. / This work aims to study the regular variations of the ionosphere at middle and low latitudes and the impact of various events on solar ionization. To quantify these changes, we will use GPS networks to measure the Total Electronic Content (TEC) .This work is part of the project ISWI. The study will include a morphological analysis on regular variations in the ionization time of the Quiet Sun (diurnal variation, seasonal and based on the solar cycle) for the treatment of GPS stations in Europe and Africa over the period analyzed (2000 to 2014); variations disturbed ionosphere associated with solar events selected according to a set of criteria; Analysis of the ROTI index to study the ionospheric scintillation generating degradation positioning at low latitudes and especially Africa.The study will continue with the comparison with existing models in order to identify their performance: the NeQuick2 model modeling software profile of the median vertical ,the ionospheric model IONEX / CODG which is a daily mapping TEC in specific spatial and temporal positions and from the post-processing of GPS measurements on a third coverage mondiale.The component of this study will give prospects for a possible anticipation of the impact of specific solar events on the ionosphere, such modeling gradients in magnetically disturbed period and prediction of the presence of ionospheric scintillation event on some ground-satellite paths.
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Ledarskapets påverkan på kreativitet : En studie om ledarskapets påverkan på kreativa arbetsprocesser hos ledare och medarbetare inom kommunikationsbyråerHellsing, Edvin, Ragnarsson, Jacob January 2018 (has links)
Studiens syfte är att utveckla kunskap om medarbetares samt ledares upplevelser av hur relationen mellan medarbetare och ledare påverkar kreativa arbetsprocesser. Som underlag för att närma oss syftet genomförde vi semistrukturerade intervjuer med nio personer, fördelade på två kommunikationsbyråer. Vi har intervjuat både ledare och medarbetare med olika befattning för att få ett brett svarsunderlag. Vi har utgått från det teoretiska ramverket Leader-Member Exchange (LMX) och har genom det perspektivet undersökt relationen mellan ledare och följare och sökt utkristallisera viktiga beståndsdelar i denna. Vi fann begreppen Autonomi, Handlingsutrymme samt Roller och rollfördelning som centrala. Genom dessa begrepp åskådliggör vi respondenternas uppfattningar av ledarskapets påverkan på kreativitet. Studiens resultat visar på att det är viktigt för ledare att ge relevant feedback och visa tillit till sina medarbetare för att främja kreativitet. Vidare bör ledare tillåta medarbetare vara experter inom sitt område genom att tillgodose dem med ett stort handlingsutrymme, inom givna ramar. Medarbetare och ledare har en samsyn om att auktoritära ledare har en negativ effekt på kreativitet då det leder till minskat handlingsutrymme för medarbetare. Ledare kan med fördel även frigöra tid för kreatörers huvudsakliga arbetsuppgifter genom att sköta administrativa uppgifter, vilket kan leda till minskad stress. Samtliga respondenter har överensstämmande upplevelser av att stress hämmar kreativitet. En medarbetare som känner ansvar för en uppgift har större benägenhet att känna lust inför arbetsuppgiften, det har i sin tur visat sig vara viktigt för kreativitet. Lust kan bl.a. ta sig uttryck i att ledare eftersträvar ett öppet arbetsklimat där dialog premieras. Ytterligare en viktig aspekt för kreativitet är respondenternas förhållningssätt till standardiserade processer. Om medarbetare arbetar efter en given mall ges inte upphov till innovativa idéer och får således inte utlopp för sin kreativitet. / The aim of the study is to develop knowledge about employees' and leaders' experiences of how the relationship between employees and leaders affect creativity. As a basis for achieving our goal, we have conducted semi-structured interviews with nine people on two advertising agencies. We have interviewed both managers and employees with different positions to get a broad response base. Based on the Leader-Member Exchange (LMX) theoretical framework, we have investigated the relationship between leaders and followers and sought to crystallize key elements of this. We found the concepts Autonomy, Space of action, and roles and role distribution as central aspects. Through these aspects we illustrate the respondents' perceptions of leadership's influence on creativity. The study's results indicate that it is important for managers to provide relevant feedback and to show faith in their employees to promote creativity. In addition, leaders should allow employees to be experts in their field by providing them with a large amount of latitude, within given limits. Both coworkers and leaders also agree that authoritarian leaders have a negative effect on creativity as it leads to reduced latitude for employees. Furthermore, leaders can advantageously emancipate time for creators' main tasks by managing administrative tasks, which can reduce the level of stress. All respondents have consistent experiences that stress inhibits creativity. A co- worker who is responsible for a task is more likely to feel comfortable with the task, which in turn has proved to be important for creativity. This may include emphasize that leaders seek an open working environment where dialogue is premiered. Another important aspect of creativity is the respondent's approach to standardized processes. If employees work is based on a given form, space is not given for innovative ideas, and employees do not get outlet for their creativity.
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Variations climatiques et variations du cycle hydrologique aux basses latitudes au cours du Quaternaire : une approche combinant modèle et données / Climate and low latitude water cycle variations during the Quaternary : a model-data approachExtier, Thomas 18 October 2019 (has links)
Le climat du Quaternaire est défini par une succession de périodes glaciaires et interglaciaires enregistrées dans les archives climatiques à différentes latitudes. La carotte de glace d’EPICA Dome C fournit un enregistrement haute résolution sur les derniers 800 ka du δ18Oatm (i.e. δ18O de la molécule d’oxygène de l’air) qui combine les variations passées du cycle hydrologique des basses latitudes et de la productivité de la biosphère. En l’absence du comptage des couches annuelles, ce proxy peut être utilisé comme méthode de datation orbitale des carottes de glace, en lien avec l’insolation au 21 juin à 65°N. Cependant, un décalage de 6 ka entre le δ18Oatm et l’insolation, généralement observé lors des terminaisons glaciaires-interglaciaires, est appliqué sur l’ensemble de l’enregistrement lors de la construction de l’échelle d’âge. Ce décalage et la complexité du signal du δ18Oatm expliquent l’incertitude élevée de 6 ka des carottes de glace, ce qui limite leur interprétation en termes de variations climatiques et environnementales conjointement à d’autres archives. J’ai donc développé une nouvelle chronologie pour les carottes de glace, basée sur le lien entre le δ18Oatm et le δ18Ocalcite des spéléothèmes est-asiatiques, à partir de nouvelles mesures isotopiques permettant d’avoir pour la première fois un enregistrement complet sur les derniers 800 ka à Dome C. Cette nouvelle chronologie permet de réduire les incertitudes par rapport à la chronologie actuelle et d’avoir une meilleure séquence des évènements entre les hautes et basses latitudes. J’ai ensuite développé un modèle simulant la composition isotopique de l’oxygène atmosphérique afin de répondre au manque d’interprétations quantitatives de ce proxy ainsi que pour vérifier son lien avec le δ18Ocalcite sur plusieurs cycles climatiques. Pour modéliser le δ18Oatm nous avons dû coupler le modèle climatique de complexité intermédiaire iLOVECLIM avec le modèle de végétation CARAIB. Le δ18Oatm simulé par le modèle couplé sur plusieurs dizaines de milliers d’années confirme que ses variations sont en phase avec celles de l’insolation de l’hémisphère Nord (hormis lors d’évènements de Heinrich) et avec celles du δ18Ocalcite via des modifications du cycle hydrologique des basses latitudes, impactant la composition isotopique de l’eau de pluie utilisée par la biosphère terrestre lors de la photosynthèse. / Quaternary glacial-interglacial cycles are recorded in various climatic archives from high to low latitudes. The EPICA Dome C ice core provides a high-resolution record over the last 800 ka of δ18Oatm (i.e. δ18O of atmospheric O2) which combines past variations of the low latitude water cycle and of the biosphere productivity. In absence of annual layer counting, this proxy can be used for orbital dating in association with the June 21st insolation at 65°N to build an ice core chronology. However a lag of 6 ka between the δ18Oatm and the insolation, classically observed during glacial-interglacial terminations, is applied to the entire record during the chronology construction. This lag and the complexity of the δ18Oatm signal are the main reasons why the ice core chronology presents a high 6 ka uncertainty which limits their interpretation, jointly with other paleoclimate archives, in terms of past climate and environmental variations. To solve this issue I have developed a new ice core chronology based on the relation between the δ18Oatm and the δ18Ocalcite of east-asian speleothems, using new isotope measurements allowing for the first time a complete record over the last 800 ka at Dome C. This new chronology reduces the uncertainties compared to the actual ice core chronology strongly based on δ18Oatm and shows a better sequence of events between the high and low latitudes records. Then, I have developed a model to reproduce the isotopic composition of atmospheric O2 to address the lack of quantitative interpretations of this proxy and to check our assumption of synchronicity with the δ18Ocalcite over several climatic cycles. To reproduce the variations of the δ18Oatm, it was necessary to couple the intermediate complexity climate model iLOVECLIM and the vegetation model CARAIB. Finally, the δ18Oatm variations simulated with the new coupled model over several thousand years are in phase with the insolation of the Northern hemisphere (except during Heinrich events) and with low latitudes δ18Ocalcite variations. This can be explained by changes in the low latitude water cycle related to changes in the isotopic composition of meteoric water used by the terrestrial biosphere during photosynthesis.
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Svobodné školy a jejich uplatnění v současném školství / Free schools and its application on contemporary educationBartošová, Alexandra January 2020 (has links)
I deal with the democratic school term in my diploma thesis. I clarify the term, I present few of the democratic schools and critical pedagogy. My goal is to highlight the qualities of the democratic school and demonstrate the arguments for considering it as equal and adequate to classical education system. I highlight the importance of attention and financial support from MŠMT for the democratic schools. Few of the democratic schools and the movements were inspired by the concept of independent british boarding Summerhill school and his founder Alexander Sutherland Neill. I will describe pedagogical principles of A. S. Nell and the history of Summerhill school in my thesis. Partial goals are to clarify in what extant and how were employed the principles of Summerhill school in schools in the Czech republic; and how can be the pedagogy of A. S. Neill followed in Czech settings. I will decribe my own point of view on the schooling and teaching. I will compare them to several schools, e.g. Scio school, Ježek bez klece school, Neškola, Sudbury Valley School, Neue Schule etc. after that. I will address the terms unschooling, democracy and boarding school. I employ a method of comparison, analogy, analisis and synthesis.
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Měření směrových charakteristik antén / Measurement of antenna radiation patternDrdla, Karel January 2008 (has links)
The aim of my diploma thesis is to produce an automated workplace for an antenna radiation pattern measurement with the R&S ESCS 30 measurement device. The result is a program named SFMAP.EXE. The measurement process is controlled by this program according to user defined parameters. The program collects the R&S ESCS 30 measured values and can evaluate the radiation angle values of the antenna. It can set up some parameters of the measurement device and controls the rotation of the turn-table, where the measured antenna is positioned. The controlling device based on FT232BL circuit was developed to capacitate the program to control the turn-table. With created program the turn-table can be controlled over the USB interface. This solution allows using any PC or notebook because of its standard equipment - the USB interface.
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