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Experimental investigation of a de-icing system for wind turbine blades based on infrared radiationSollén, Sofia, Pettersson, Jennifer January 2019 (has links)
Wind power is one of the fastest growing production methods of electric energy. The expansion of wind power in Sweden are focused to northern counties. There are advantages as good wind conditions and large unexploited areas to build wind farms in the north, but there are also problems caused by the long winters. Due to the long periods of cold climate, ice and snow accumulation on blades are a safety risk, induces production losses and causes wear at wind turbine components. The commercial de-icing systems are not fulfilling the demands of being cost effective and are mainly focusing the heating to the leading edge. Therefore a new de-icing system based on infrared radiation has been investigated. This system is supposed to be placed at the wind turbine tower and de-ice one blade at a time. Experiments with this new de-icing system has been performed in small and full scale at a section of a real wind turbine blade. The experiments were carried out in facilities of Arctic Falls in Piteå. Different parameters as power demand of the heaters, distance between blade and heaters, wavelength of the radiation, influence by the surrounding temperature and total de-icing time were evaluated. Results showed that the largest impact of the efficiency and de-icing time were induced by the distance and width of the radiation spectrum for the heaters. Three types of filaments with different peaks of wavelengths were investigated and the most efficient de-icing was achieved when using a combination of heaters. Measurements of intensity together with de-icing experiments showed that the optimal distance from the blade was 1.5 m for heaters with standard reflectors. The main conclusion from the experiments with an infrared de-icing system is that it works. But not efficient enough to compete with the commercial systems of today even though it manage to de-ice the whole blade instead of just the leading edge. But this de-icing system has good potential if the heaters first of all are developed to radiate a more concentrated beam of radiation that is only focusing at the blades. The new method is estimated to be an lower investment due to that the techniques of infrared heaters are already well implemented in other areas. But more economic calculations has to be done to further motivate the work.
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Ochranářská genetika vlka obecného a levharta sněžného: vliv krajiny na mikroevoluci populační struktury / Conservation genetics of grey wolf and snow leopard: effect of landscape attributes to the population structureBenešová, Markéta January 2018 (has links)
Landscape genetic approaches allow to study effects of landscape to population microevolution. Landscape can influence gene flow even in large carnivores with good dispersal ability. Understanding the influence of landscape to the gene flow between populations is crucial for species conservation, especially in the species with low population densities. Aim of the study was to describe genetic structure of the grey wolf (Canis lupus) and snow leopard (Panthera uncia) in selected areas and to determine the influence of the landscape features on observed structure. Non-invasive genetic samples of snow leopard from Nepal were analysed, as well as invasive and non-invasive samples of grey wolf from Central Europe. Population structure was determined a posteriori using Bayesian clustering approaches that integrate genetic and geographical data, and compared to landscape connectivity models. Population structure of snow leopards is mostly influenced by human presence and presence of frequented roads, which represent a substantial dispersal barrier. Habitat suitable for this species is greatly restricted by altitude, however, during dispersal they are able to overcome areas with higher elevation than what is optimal for them. Pronounced genetic difference was found between central European and Carpathian...
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Optimization of Operational Overhead based on the Evaluation of Current Snow Maintenance System : A Case Study of Borlänge, SwedenRaihana, Nishat January 2019 (has links)
This study analyzes snow maintenance data of Borlänge municipality of Sweden based on the data of 2017 to 2018. The goal of this study is to reduce operational overhead of snow maintenance, for example, fuel and time consumption of the snow maintenance vehicles, work hour of dedicated personnel, etc. Borlänge Energy equipped the snow maintenance vehicles with GPS devices which stored the record of the snow maintenance activities. The initial part of this study obtained insights out of the GPS data by using spatiotemporal data analysis. Derivation of the different snow maintenance treatments (plowing, sanding and salting) as well as the efficiency of the sub-contractors (companies which are responsible for snow maintenance) and inspectors (personnel who are liable to call the subcontractors if they think it is time for snow maintenance) are performed in the beginning of this study. The efficiency of the subcontractors and inspectors are measured to compare their performance with each other. The latter part of this study discusses a simulated annealing-based heuristics technique to find out optimal location for dispatching snow maintenance vehicles. In the existing system of snow maintenance, drivers of the maintenance vehicles decide to start location of maintenance work based on their experience and intuition, which might vary from one driver to another driver. The vehicle dispatch locations are calculated based on the availability of the vehicles. For example, if a subcontractor has three vehicles to perform snow maintenance on a specific road map, the proposed solution would suggest three locations to dispatch those vehicles. The purpose of finding the optimal dispatch location is to reduce the total travel distance of the maintenance vehicles, which yield less fuel and time consumption. The study result shows the average travel distance for 1, 3, and 5 vehicles on 15 road networks. The proposed solution would yield 18% less travel than the existing system of snow maintenance.
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Unapređenje metodologije procene bezbednosti i zdravlja na radu za slučaj snežnih lavina izazvanih zemljotresom / Improving the methodology for assessing occupational safety and health in the case ofearthquake-induced snow avalanchesBajić Senka 22 March 2019 (has links)
<p>Snežne lavine izazvane zemljotresima su fenomen koji se još uvek istražuje, iako je prisutan u skoro svim planinskim regionima širom sveta. U okviru ove doktorske disertacije razvijena je i unapređena metoda procene bezbednosti i zdravlja na radu za slučaj snežnih lavina izazvanih zemljotresom. Osnovni cilj unapređene metode je smanjenje rizika na najmanji mogući nivo, odnosno prihvatanje najmanjeg mogućeg rezidualnog rizika, čije dalje smanjenje ili uklanjanje ne bi bilo isplativo. Unapređena metoda uzima u obzir niz faktora (duboku geologiju, sastav stena, visinu snežnog pokrivača, rasprostranjenost kritičnih nagiba, itd.) koji mogu da utiču na pojavu snežnih lavina uzrokovanih zemljotresom. Za verifikaciju metode uzet je skijaški centar Kopaonik, koji nije dovoljno istražen, iako je jedan od najvećih centara u jugoistočnom delu Evrope.</p> / <p>Snow avalanches caused by earthquakes are a subject of many researches, even<br />though this phenomenon is present in mountain regions around the world. In this<br />doctoral dissertation, an improved method of assessing occupational health and safety<br />in cases of earthquake-induced snow avalanches has also been developed. The main<br />goal of the improved method is to reduce the risk to the smallest possible level, i.e. to<br />accept the least possible residual risk, the further reduction or removal of which would<br />not be profitable. This method takes into account a number of factors (deep geology,<br />rock composition, snow cover height, critical inclination distribution, etc.) that can affect<br />the occurrence of the earthquake-induced snow avalanches. For the verification of the<br />method, the ski center Kopaonik was analyzed, which has not been sufficiently<br />explored, although it is one of the largest ski centers in south-eastern part of Europe.</p>
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Etude de la couche de surface atmosphérique et des flux turbulents sur deux glaciers de montagne dans les Andes tropicales et les alpes Françaises / A study of the atmospheric surface layer and turbulent fluxes on two mountain glaciers in the Tropical Andes and in the French AlpsLitt, Maxime 16 February 2015 (has links)
Nous étudions les flux turbulents de chaleur sensible et de chaleur latente, qui sont mal compris et mal mesurés sur les glaciers, à l'aide de campagnes de terrain déployées dans la zone d'ablation du glacier tropical du Zongo (16°S, Bolivie, 4900-6000 m) durant la saison sèche de l'hiver austral et sur le glacier alpin de Saint-Sorlin (Alpes Françaises, 45°N, 2600-3400 m) durant l'été boréal. Un mât de 6 m permettait la mesure des profils verticaux de vitesse de vent et de température de l'air et des mâts de 2 m comportaient des systèmes de covariances turbulentes (CT). Nous étudions l'évolution temporelle des flux turbulents et l'applicabilité de la méthode aérodynamique des profils en terrain complexe de montagne. Les hypothèses sont discutées via la caractérisation des régimes de vent et de la turbulence. Nous calculons ensuite les flux et les erreurs associées. Sur le Zongo, sous forçage synoptique faible, un écoulement catabatique s'installe de la fin d'après-midi jusqu'au matin, avec un maximum de vitesse de vent à environ 2 m de hauteur. Les forçages synoptiques forts s'alignent approximativement avec le glacier, provoquant un intense écoulement descendant, et dans ce cas nous n'observons pas de maximum de vitesse de vent. Souvent, autour de midi, des vents ascendants sont observés. Sur le glacier de Saint-Sorlin les forçages associés à des épisodes de Foehn ou à des dépressions se déplaçant depuis l'ouest, s'alignent approximativement avec le glacier, générant des vents forts descendants. Quand le forçage synoptique est modéré, un maximum de vitesse de vent est observé nuit et jour 50% du temps. Des vents ascendants sont observés 15% du temps, quand le forçage synoptique est faible. La couche de surface est perturbée par des tourbillons de couches externes sous vent fort, ou de lentes oscillations en écoulement catabatique. Ces perturbations influencent les flux turbulents. Les erreurs aléatoires sur la méthode des profils sont dues principalement à des incertitudes sur la température. L'erreur reste faible sur les flux moyens. La couche de surface est rarement plus épaisse que 2 m et la méthode des profils appliquée à l'aide des mesures plus obtenus plus haut sous-estime les flux de surface de 20% à 70% . Quand un maximum de vitesse de vent est observé, les flux sont sous-estimés même à 2 m. L'influence des perturbations de la couche de surface n'est pas capturée par la méthode des profils, et les flux sont environ 40% inférieurs à ceux mesurés par CT. Ces derniers sont affectés par d'importantes erreurs aléatoires, en raison d'un échantillonnage statistique insuffisant des grands tourbillons. La méthode sous-estime probablement les flux à cause d'une sous-estimation de la vitesse verticale (~15%) et de la divergence verticale des flux. Sur le glacier du Zongo, l'air de haute altitude est très sec et la sublimation (quelques mm d'eau par jour) est un important puits d'énergie à la surface. Le flux de chaleur sensible est un important gain d'énergie la nuit sous l'influence de vents forts (de 30 à 50 W m-2), car l'inversion de température est marquée. Quand un maximum de vitesse de vent est observé, les flux sont faibles (de 5 à 20 W m-2) car la vitesse du vent est faible. La somme des flux turbulents est faible dans ces deux cas car ils sont opposés et les biais se compensent. En vent ascendant, le flux de chaleur sensible est faible (<5 W m-2) car la stratification est neutre, mais le flux de chaleur latente reste important (de -25 à -35 W m-2), le flux net est donc important et les biais ne se compensent plus. Sur le glacier de Saint-Sorlin, le flux de chaleur latente est faible car l'air est humide, et le flux de chaleur sensible peut être intense (~25 W m-2) quand la vitesse du vent est élevée. Le flux net est fort par vent fort et les biais sur les flux calculés par la méthode des profils peuvent être élevés. / We study turbulent fluxes of sensible and latent heat, that are a poorly-known and difficult term to measure over glaciers, with the help of two field campaigns deployed over the ablation zone of Zongo glacier (16°S, Bolivia, 4900-6000 m.a.s.l.) during the austral winter dry season and over the Saint-Sorlin glacier (French Alps, 45°N, 2600-3400 m.a.s.l.) during the boreal summer. A 6-m mast allowing for wind speed and air temperature vertical profile measurements was installed, along with 2-m masts holding eddy-covariance systems. The focus is on the temporal evolution of turbulent fluxes and the applicability of the aerodynamic profile method in the complex terrain of high mountains. The assumptions of the method are discussed by characterizing the wind regimes and the turbulence. We then compute fluxes and associated errors. Above Zongo glacier, under weak synoptic forcing, katabatic flows are observed from late afternoon to early morning, with a wind-speed maximum at around 2 m. Strong synoptic forcing roughly aligns with the glacier, leading to strong downslope flows for which no wind-speed maximum is observed. Most of the days around noon, upslope flows are observed. On Saint-Sorlin glacier in summer, flows associated with low-pressure systems coming from the west or Foehn events roughly align with the glacier, leading to strong downslope winds. Wind-speed maxima are observed night and day, ~50% of the time, when synoptic forcing is moderate. Upslope flows are observed 15% of the time, when synoptic forcing is weak. The surface layer is disturbed by outer-layer eddies in strong flows and by slow oscillations if katabatic flow prevails. These disturbances influence turbulent fluxes. Random errors on the fluxes derived from the profile method are mainly due to temperature uncertainties. Errors remain small on the mean fluxes. The surface layer is rarely deeper than 2 m on both glaciers and the profile method with measurements made above that height underestimates the surface fluxes by 20% to 70%. When a wind-speed maximum is observed, fluxes are underestimated even at 2 m. The influence on the fluxes of the surface-layer disturbances is not captured by the profile method, and fluxes are about 40% smaller than the eddy-covariance fluxes. The latter are affected by large random errors due to inadequate statistical sampling of large-scale eddies and are probably underestimated, mainly due to vertical wind speed underestimation (~15%) and to vertical flux divergence. Above Zongo glacier, due to the dry high-elevation air, sublimation (a few millimeters w. e. per day) is a large energy loss for the surface. Sensible heat flux is a large energy gain in strong nocturnal downslope flows (from 30 to 50 W m-2) and strong winds, due to a marked temperature inversion. When a wind-speed maximum is observed, low wind speeds cause small turbulent fluxes (from 5 to 20 W m-2). The sum of turbulent fluxes is small in those two cases because the fluxes are opposed in sign and the biases mostly compensate. In upslope flows, the sensible heat flux is small (<5 W m-2) due to near-neutral stratification, but latent heat losses remain large (around -25 to -35 W m-2), so that the net turbulent flux is large and the biases do not compensate. Above Saint-Sorlin glacier, the latent heat flux remains small because the air is generally humid, whereas the sensible heat flux can be large (~25 W m-2) when wind speed is high. The net flux is large when wind speed is high, and the biases on net turbulent fluxes derived from the profiles can be significant.
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Changement climatique et dynamique de la végétation dans les Andes du Chili central, depuis le milieu du XXème siècle : l'exemple de la vallée de Yerba Loca / Climate change and vegetation dynamics in the Andes of central Chile since the mid-twentieth century : the case of Yerba Loca valleyQuense, Jorge 23 September 2011 (has links)
Les milieux oroméditerranéens sont considérés comme particulièrement sensibles aux changements climatiques. Deux questions sont posées dans ce contexte : quelles sont la nature et l'ampleur des modifications climatiques à l'échelle régionale (climat et enneigement) au Chili central, depuis les années 70 ? Quels sont les changements de la végétation en montagne (dans la tranche d'altitude 1.500 - 2.500 m), en particulier au niveau de la limite supérieure de la forêt à Kageneckia angustifolia ? La première partie de la thèse présente les spécificités des milieux de montagne et les changements climatiques déjà observés de façon générale et au Chili en particulier. Elle présente aussi les sites d'étude au niveau climatique et biogéographique. La deuxième partie concerne les données et la méthodologie. Une approche scalaire est mise œuvre, avec confrontation et mise en complémentarité de différentes techniques : télédétection, chroniques climatiques et mesures in situ. La troisième partie présente les résultats. Les données climatiques enregistrées les 30 dernières années aux stations d'El Yeso (2.500 m) et de Los Bronces (3.500 m), montre une croissance d'environ 1 °C pour la température moyenne annuelle, réchauffement plus marqué à El Yeso, au niveau des températures minimales. Pour l'enneigement, il est montré une haute variation interannuelle de la couverture de neige et une élévation de la limite de la neige durant les dernières décennies, d'environ 300 m. Ces résultats, sont accompagnés d'une augmentation faible du NDVI. Au niveau de la vallée Yerba Loca, l'étude diachronique de l'écotone supraforestier montre des transformations vers une augmentation de la superficie des espaces forestiers et leur densification. Enfin, l'expérience de germination, à Yerba Loca montre qu'il existe une différence significative entre le pourcentage de germination des graines à l'intérieur des enclos et à l'extérieur, avec un effet négatif de la couverture neigeuse sur la germination des plantules. / Mediterranean areas are considered particularly sensitive to climate change. Two questions are asked in this context: what is the nature and magnitude of regional climate change (climate and snow cover) in central Chile, since the 70's? What are the changes in mountain vegetation (in the altitude range of 1,500-2,500 m), especially at the upper limit of Kageneckia angustifolia forest? The first part of the thesis shows the characteristics of mountain environments and observed climate change at global and Chilean local level. It also presents the study area, from the standpoint of biogeography and climate. The second part refers to the data and methodology. We used a multiscale approach to the confrontation and the application of several complementary techniques: remote sensing, climatic data and field measurements. The third part presents the results. Climate data recorded in the last 30 years in the stations of El Yeso (2,500 m) and Los Bronces (3,500 m), shows an increase of about 1° C in mean annual temperature, been the sharpest increase in El Yeso, especially in average of low temperatures. In relation to snow cover, it shows high variation and a rise up in the limit of snowline in recent decades, about 300 m. These results are accompanied by a slight increase in NDVI. In the Yerba Loca valley, the diachronic study of Kageneckia angustifolia forest ecotone shows changes towards an increase forest areas and densification. Finally, the experience of germination in Yerba Loca indicates a significant difference between the percentage of germination of the seeds under protection from snow and the ones without treatment, with a negative effect of snow cover on the germination.
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Iodine, Bromine, and Chlorine – Emission Rates and SourcesAngela R. Raso (5930183) 18 December 2018 (has links)
<div>Halogen chemistry in the Arctic boundary layer catalytically destroys O3 and impacts the chemical lifetimes of hydrocarbons, the HOx-NOx cycle, and atmospheric mercury. While many advances have been made in the last several decades in understanding the sources, sinks, and recycling pathways of halogens in the Arctic there are still many unknowns. Previous studies have shown that Br2, BrCl and Cl2 are produced photochemically in the Arctic tundra snowpack, but the magnitude of this production is still poorly understood. Additionally, while there have been suggestions that the tundra snowpack should also produce I2, there have been no previous measurements of I2 in the Arctic. The lack of measurements of the halogen production capacity of Arctic snowpacks has left the community to rely on one-dimensional modeling to estimate the impact of snowpack-derived halogen chemistry on the Arctic atmosphere. Because modeling is inherently dependent on understanding recycling mechanisms, mixing processes, and sinks this leaves the effect of halogens on atmospheric chemistry in the Arctic highly uncertain.</div><div><br></div><div>This work describes efforts to address these uncertainties through measurements made during two field campaigns in Utqiaġvik (formerly Barrow), Alaska in January – February 2014, and February – May 2016. The first measurements of I2 in the Arctic, both in the snowpack interstitial air, and in the air above the snowpack demonstrate that iodine chemistry is active in the Arctic atmosphere, and that I2 is produced photochemically in the tundra snowpack. The effects of active iodine chemistry on both O3 and bromine chemistry is examined through zero- and one dimensional modeling. The first speciated measurements of snowpack phase iodine reveal that much like previous reports of iodine enriched aerosols, the Arctic snowpack is highly enriched in iodine. Vertical profiles of I- in the snowpack suggest that there is a consistent, non-radiation dependent source of iodine to the Arctic environment. It seems likely that this source is transport of iodine-enriched aerosols from the mid-latitudes. However, unlike the Antarctic, and previous</div><div>observations in the mid-latitudes, most Arctic snowpack phase iodine is inorganic, which may contradict transport from the mid-latitudes as a source. One-dimensional modeling was also utilized, in conjunction with the first vertical profile measurements of Br2 and Cl2 between 1 and</div><div>7 m above the snowpack surface to examine the community’s understanding of recycling mechanisms, mixing, sources, and sinks of halogens in the Arctic Atmosphere.</div>
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Literatura, cinema, parques e produtos: Branca de Neve e suas traduções intersemióticasSilva, Débora Cibele de Benedetto e 31 March 2014 (has links)
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Previous issue date: 2014-03-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Approximately one hundred years after its first publication in Children s and Household Tales, by Jacob and Wilhelm Grimm, the tale Snow White is translated into a movie by the Disney Studio in 1937; Snow White and the Seven Dwarfs is the first full length animated film in the history of the movies. Due to its enormous success, Snow White and the Seven Dwarfs becomes one of the definite versions of the tale registered by the Brothers Grimm. What is more, this version influences countless other productions made after its release. Subsequently, the Disney Company devises other intersemiotic translations to the tale, some of which are attractions in Disney theme parks and various retail products sold by the Disney Store. Such an expansion characterizes Disney as an expansionist company which makes of use of a portfolio of brands and media to differentiate content in order to develop creative, innovative and profitable entertainment experiences and related products. The translations to Snow White made by the Disney Company allow the audience to interact with the characters and universe of the movie in a deeper way and, moreover, they increase the niches of consumers who may appreciate the story. An academic study about such intersemiotic translations may help us comprehend in which ways the audience, in general, interacts with fairy tales nowadays. In order to do so, the following dissertation proposes a dialogue between literature, movies and communication, and presents an analytical thinking process which starts with a literary analysis of the Grimm s tale, reflects upon the concept of intersemiotic translation and then focuses on some of the translations to Snow White devised by Disney. / Aproximadamente cem anos após sua primeira publicação em Contos de Fadas para Crianças e Adultos, de Jacob e Wilhelm Grimm, o conto Branca de Neve ganha, em 1937, uma tradução intersemiótica para o cinema produzida pelos estúdios Disney; trata-se da animação Branca de Neve e os Sete Anões, a primeira animação de longa-metragem da história do cinema. O enorme sucesso do filme confere a ele o caráter de uma das versões definitivas do conto original registrado pelos Irmãos Grimm. Além disso, a versão Disney acaba por influenciar inúmeras produções posteriores a ela. A partir de Branca de Neve e os Sete Anões, a empresa Disney lança novas traduções intersemióticas para a narrativa, como atrações em parques temáticos, jogos interativos, uma linha de produtos diversos e serviços de planejamento de eventos. Tal prática vai de acordo com a mentalidade expansionista dessa empresa que almeja o desenvolvimento de produtos e meios de entretenimento criativos e rentáveis a partir da diferenciação de conteúdos e de marcas em uma variedade de mídias. As traduções intersemióticas de Branca de Neve propostas pelas Disney proporcionam ao público maior poder de interação com as personagens e com o universo da narrativa e, além disso, podem ocasionar um aumento de nichos de consumidores da história. Um estudo acadêmico sobre tais traduções pode nos levar a compreender de que maneira o público, de modo geral, relaciona-se com os contos na atualidade. Para tanto, o presente trabalho propõe um diálogo entre literatura, cinema e comunicação, e apresenta um percurso analítico que parte da análise literária do conto dos Grimm, avança para reflexões acerca do conceito de tradução intersemiótica e, finalmente, debruça-se sobre algumas das traduções de Branca de Neve compostas pela Disney.
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Variações na extensão da cobertura de gelo do Nevado Cololo, BolíviaOliveira, Ana Maria Sanches Dorneles Ferreira de January 2013 (has links)
Este estudo apresenta padrões de flutuações das geleiras do Nevado Cololo, Bolívia, no período 1975–2011, determinado partir de dados orbitais, cartográficos e climáticos. As massas de gelo do Nevado Cololo são representativas das geleiras tropicais andinas que estão sujeitas a alternância entre condições atmosféricas úmidas (novembro-abril) e secas (maio-outubro) (outer tropics). Essa sazonalidade é determinada pela oscilação latitudinal da Zona de Convergência Intertropical (ZCIT) e perturbada pelos eventos não sazonais do fenômeno ENOS. A fase positiva, o El Niño, contribui negativamente para o balanço de massa dessas geleiras e foi frequente no intervalo investigado. Esse trabalho usou imagens TM/Landsat-5 para determinar a cobertura de gelo em 1989, 1997, 2008 e 2011. Aplicando o Normalized Difference Snow Index (NDSI), que utiliza as características espectrais opostas das massas de gelo no visível e no infravermelho próximo, este trabalho delimitou as geleiras do Nevado Cololo. Utilizando as informações de carta topográfica foi obtido um Modelo Digital de Elevação (MDE), elaborado pela interpolação de pontos de elevação usando o método geoestatístico krigagem ordinária. As informações obtidas do sensoriamento remoto e da cartografia foram incorporadas a um Sistema de Informação Geográfica (SIG) para se obter parâmetros das geleiras. A análise da séries temporais de precipitação e temperatura usaram dados do Global Precipitation Climatology Centre (GPCC)/NOAA, do Climate Research Unit Time Series (CRUTS)/University of East Anglia e de duas estações meteorológicas. Os dados climáticos não apresentam tendências estatisticamente significativas, mas há uma fraca redução da precipitação durante os meses de novembro, dezembro e abril, condições essa que podem indicar menor nebulosidade durante o verão. Em 2011 só restavam 48 das 122 geleiras identificadas em 1975. Geleiras pequenas (< 0,1 km²) com cotas máximas baixas foram as mais afetadas e atualmente não existem geleiras abaixo de 4.626 m a.n.m. A cobertura de gelo era de 24,77 ±0,00032 km² em 2011, 42,02% menor do que em 1975. A perda superficial ocorreu em todas as vertentes, independente de orientação, mas as geleiras voltadas a leste foram mais afetadas. Mesmo a maior geleira do Nevado Cololo, face SW, perdeu 21,6% de sua área total e sua frente retraiu cerca de 1 km durante o intervalo de 36 anos. Proporcionalmente, houve o aumento do número de geleiras cuja declividade média está entre 30° e 40°. A redução da espessura gelo é atestada pela fragmentação de geleiras e afloramentos do embasamento em suas partes internas. A perda de massa dessas geleiras estudadas foi provavelmente causada pela intensificação dos processos de ablação. / This study presents fluctuations patterns for the Nevado Cololo glaciers, Bolivia, in the period 1975–2011, as determined from orbital, cartographic and climatic data. Nevado Cololo ice masses are representative of Andean tropical glaciers subjected to alternations of humid (November to April) and dry (May to October) (outer tropics) atmospheric conditions. This seasonality is determined by the Inter-tropical Convergence Zone (ITCZ) latitudinal oscillation and disturbed by the no seasonal ENSO phenomena. The positive phase, El Niño, contributes negatively to these glaciers mass balance and was frequent during the investigated time period. This work used TM/ Landsat-5 imagery to determine the ice cover in 1989, 1997, 2008 and 2011. Applying the Normalized Snow Difference Index (NDIS), which uses the opposite spectral characteristics of ice masses in the visible and near infrared region, this work delimited the Nevado Cololo glaciers. Based on information from a topographic chart, we obtained a Digital Elevation Model (DEM) using elevation points interpolated by the ordinary kriging geostatistical method. Information derived from remote sensing and cartographic sources was incorporated into a Geographic Information System (GIS) to obtain glaciers parameters. The analyses of precipitation and temperature time series used data from the Global Precipitation Climatology Centre (GPCC)/NOAA, the Climate Research Unit Time Series (CRUTS)/University of East Anglia and from two meteorological stations. Climatic data show no statistically significant trend, but there was a weak precipitation reduction during November, December and April months, a condition that may indicate low cloudiness during the summer. By 2011, there were only 48 of the 122 glaciers identified in 1975. Small glaciers (<0.1 km²) with low maximum elevations were most affected and currently there are no glaciers below 4,626 m asl. The ice covered 24.77 km² in 2011, 42.02% less than in 1975. Surface loss occurred in all slopes, regardless of orientation, but glaciers facing east were most affected. Even the largest glacier in Nevado Cololo, SW face, lost 21.6% of its total area and its front retreated about 1 km during the 36 years period. Proportionately, there was an increase in the number of glaciers whose average slope is between 30° and 40°. The ice thickness reduction is attested by glaciers break up and bedrock outcrops in its internal parts. These glaciers mass loss was probably caused by the intensification of ablation processes.
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The Convert as a Social Type: A Critical Assessment of the Snow-Machalek Conversion Typology as Applied to British Mormon ConvertsO'Banion, Joy A. 01 January 1988 (has links)
The study was designed to be a critical assessment of the Snow-Machalek Conversion Typology. Data were collected from Mormon converts in the British Isles, and an attempt was made to apply the typology to these converts. It was assumed that if the typology could be effectively applied to Mormon converts, strong correlations would be found between its dimensions and quantitative measures of conversion. It was also assumed that social integration of converts would play an important part in the conversion process. The application of the typology proved to be very difficult; however, some dimensions seemed to be more useful than others. Social integration was very important for British converts to Mormonism. An alternative theoretical emphasis to the study of conversion is offered which stresses the importance of social integration in the development of a new global perspective.
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