• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • 3
  • 1
  • 1
  • 1
  • Tagged with
  • 12
  • 12
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
1

A quadratic cumulative production model for the material balance of an abnormally pressured gas reservoir

Gonzalez, Felix Eduardo 17 February 2005 (has links)
The premise of this research is the concept, development, and application of an approximate relation for the material balance of abnormally-pressured gas reservoirs. The approximation is formulated directly from the rigorous material balance for the case of an abnormally-pressured gas reservoir. The primary assumption in this derivation is that WGp <1 or Ce(p)(pi-p)<1. Further, we can proceed by assuming that W is either constant or some arbitrary function. If we assume W=constant, then the following form results: At first glance there may be concern that this approximation is not sufficiently valid for field applications — however, we have shown this relation to be an extraordinarily accurate approximation of the rigorous material balance. This result is suited not only for use as a characteristic model, but also for use as a data analysis mechanism (i.e., this result is used to develop a suite of analysis plots, plotting functions, a type curve, etc.). In this work we provide the following new results: 1) A suite of 6 (six) plotting functions based on the p/z-Gp2 material balance model. 2) A suite of 4 (four) p/z-Gp performance plots which are used to calibrate analysis. 3) A new type curve in terms of a dimensionless pressure function (pD=(pi/zi-p/z)/pi/zi) versus a dimensionless cumulative production function (GpD=Gp/G), where the type curve solution is based on the new p/z-Gp^2 (a quadratic material balance) model.
2

Estudo fenomenologico do reator batelada alimentada utilizando dois processos fermentativos distintos / Phenomenological study of the fed-batch reactor using two distinct fermentation processes

Gonzales, Tatiane Araujo 03 August 2018 (has links)
Orientador: Ranulfo Monte Alegre / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T21:39:56Z (GMT). No. of bitstreams: 1 Gonzales_TatianeAraujo_M.pdf: 808675 bytes, checksum: 754d8f090b92f6186edb2bc0bad0c5b2 (MD5) Previous issue date: 2004 / Resumo: O processo de batelada alimentada é útil para o estudo da cinética de processos fermentativos, pois permite a manutenção de baixos níveis de substrato por longo período de tempo, que é favorável à estimativa de parâmetros cinéticos; permite manter concentração celular constante e controlar a velocidade de crescimento em condições transientes. São as equações cinéticas que indicam como as variáveis de estado do processo em estudo interferem nas velocidades de crescimento e morte celular, de geração de produtos metabólicos e de consumo de substrato. Estudos de biorreatores de batelada alimentada têm sido freqüentemente relatados na literatura, entretanto para a modelagem destes processos necessita-se conhecer parâmetros cinéticos e informações sobre estes são escassas. A implantação do PROÁLCOOL no Brasil fez aumentar o número de destilarias. Atualmente, o processo de batelada alimentada responde por cerca de 60% do volume de etanol produzido. Outro processo fermentativo de alto valor comercial é a produção de ácido lático, uma vez que este tem grande aplicação no uso em alimentos, na área farmacêutica, de plásticos e indústria química. Desta forma, o objetivo deste trabalho foi estudar duas fermentações distintas com relação à cinética de produção e entender a fenomenologia do processo de batelada alimentada. Escolheram-se dois tipos de fermentações com cinética de produção diferentes, uma alcoólica e outra lática, o primeiro com produção associada ao crescimento e o outro de produção parcialmente associada ao crescimento. Realizaram-se ensaios de fermentações em batelada para obtenção dos parâmetros cinéticos e em batelada alimentada para aplicação dos parâmetros obtidos em modelos e estes em balanço de massa do processo batelada alimentada. Em seguida, foram conduzidas simulações do processo batelada alimentada com o auxílio do software AnaBio 1.0 e ajustados os parâmetros cinéticos através de análise visual, utilizando-se dois modelos encontrados na literatura: o modelo cinético de Monod e outro também baseado em Monod com inclusão de um termo de inibição pelo produto. Estes modelos representaram visualmente os dados experimentais de forma satisfatória para a fermentação alcoólica, no entanto, somente um ajuste regular dos dados experimentais em relação aos preditos foram obtidos para fermentação lática / Abstract: The fed-batch process is useful for studying of fermentation process kinetic, because it allows keeping low level of substrate for a long period, which is favorable to estimate kinetic parameters; it enables keeping a constant biomass concentration and controlling growing rate in transient conditions. The kinetic equations indicate how the process variables interfere in the cell growing rate and death, the metabolic product formation and substrate consumption. The bioreactors studies of fed-batch have been often found on specialized literature, however, its necessary to know the kinetic parameters that are not available. A very important program in Brazil, called PROALCOOL, leveraged a raise in the number of alcohol industries and 60% of ethanol assembled in this country, in the present time, use fed-batch process. Another interesting process is the production of lactic acid, which is important to food, pharmaceutical, plastic and chemical industry. Therefore the main objective of this project was to study two different fermentation processes to apply the material balance of the fed-batch reactor with determined parameters and known mathematical models. Two production kinetic fermentations were chosen, one alcoholic and another lactic. The first one is associated with the cell growth and the other is partially associated with cell growth. Some batch fermentations essays were carried out to obtain kinetics parameters and fed-batch processes were performed to study the kinetic process. Simulations of fed-batch process, running the software Anabio 1.0, were executed and the kinetic parameters fitted through visual analysis, using two known models, Monod kinetic model and Monod including inhibitory effect of product. Theses models were better visually represented by the alcoholic fermentation experimental data than lactic fermentation data. In the condition of the fed-batch assays the Monod or Monod with inhibitory effect of product inserted in the material balance do not describe these process / Mestrado / Mestre em Engenharia de Alimentos
3

Improving long-term production data analysis using analogs to pressure transient analysis techniques

Okunola, Damola Sulaiman 15 May 2009 (has links)
In practice today, pressure transient analysis (PTA) and production data analysis (PDA) are done separately and differently by different interpreters in different companies using different analysis techniques, different interpreter-dependent inputs, on pressure and production rate data from the same well, with different software packages. This has led to different analyses outputs and characterizations of the same reservoir. To avoid inconsistent results from different interpretations, this study presents a new way to integrate PTA and PDA on a single diagnostic plot to account for and see the early time and mid-time responses (from the transient tests) and late time (boundary affected/PSS) responses achievable with production analysis, on the same plot; thereby unifying short and long-term analyses and improving the reservoir characterization. The rate normalized pressure (RNP) technique was combined with conventional pressure buildup PTA technique. Data processing algorithms were formulated to improve plot presentation and a stepwise analysis procedure is presented to apply the new technique. The new technique is simple to use and the same conventional interpretation techniques as PTA apply. We have applied the technique to a simulated well case and two field cases. Finally, this new technique represents improvements over previous PDA methods and can help give a long term dynamic description of the well’s drainage area.
4

Data Bias in Rate Transient Analysis of Shale Gas Wells

Agnia, Ammar Khalifa Mohammed 2012 May 1900 (has links)
Superposition time functions offer one of the effective ways of handling variable-rate data. However, they can also be biased and misleading the engineer to the wrong diagnosis and eventually to the wrong analysis. Since the superposition time functions involve rate as essential constituent, the superposition time is affected greatly with rate issues. Production data of shale gas wells are usually subjected to operating issues that yield noise and outliers. Whenever the rate data is noisy or contains outliers, it will be hard to distinguish their effects from common regime if the superposition time functions are used as plotting time function on log-log plots. Such deceiving presence of these flow regimes will define erroneous well and reservoir parameters. Based on these results and with the upsurge of energy needs there might be some costly decisions will be taken such as refracting or re-stimulating the well especially in tight formations. In this work, a simple technique is presented in order to rapidly check whether there is data bias on the superposition-time specialized plots or not. The technique is based on evaluating the kernel of the superposition time function of each flow regime for the maximum production time. Whatever beyond the Kernel-Equivalent Maximum Production Time (KEMPT) it is considered as biased data. The hypothesis of this technique is that there is no way to see in the reservoir more than what has been seen. A workflow involving different diagnostic and filtering techniques has been proposed to verify proposed notion. Different synthetic and field examples were used in this study. Once the all problematic issues have been detected and filtered out, it was clear that whatever went beyond the KEMPT is a consequence of these issues. Thus, the proposed KEMPT technique can be relied on in order to detect and filter out the biased data points on superposition-time log-log plots. Both raw and filtered data were analyzed using type-curve matching of linear flow type-curves for calculating the original gas in-place (OGIP). It has been found that biased data yield noticeable reduced OGIP. Such reduction is attributed to the early fictitious onset of boundary dominated flow, where early false detection of the drainage boundaries defines less gas in-place occupied in these boundaries.
5

Small-scale biogas and greenhouse system / Småskaligt biogas- och växthussystem

Tran, Stephan, Alexandersson, Robert January 2017 (has links)
Greenhouse cultivation is a growing industry, especially in mild climates, much due to the ability toadjust the growing conditions and increased water utilization efficiency. The most important aspect onthe cultivation is the indoor temperature. The variation in temperature is due to the Swedish climatewhere the highest and lowest outdoor temperature respectively varies greatly during the year. To enableoptimal indoor climate additional heating is required during colder periods. Presently, most of theexisting greenhouses utilizes combustion of fossil fuels for heating, which contributes to the climatechange through the emissions of greenhouse gases. One way to circumvent this impact is to exchangethe fossil fuels with biogas. Combining biogas production and greenhouse cultivation enables synergiesand a more closed cycle of material flow can be achieved. However, this combination is rather immaturedue to lacking previous research, giving this report its main purpose, to examine the synergies andsustainability of combining a greenhouse with small-scale biogas production. Initially, an extensive literature study was carried out followed by a simulation based on the obtainedknowledge. The simulation was comprised of two greenhouses with different geometries, one with theshape of an arch with polyethylene-film cladding and the other with a sawtooth roof with glass cladding,both with two layers. The other properties such as internal area and volume are more or less the samefor the simulated greenhouses. Useful data such as outdoor temperature, rainfall and solar irradiationetc. was obtained for the city of Enköping, Sweden. The calculations for the models were carried out inthe program Microsoft Excel. In order to evaluate the feasibility of these models a reference greenhousewas studied, which had similar properties and conditions. The optimal temperature for tomato cultivation is 20° C, and to maintain this level over the entire yearit was found that the heat requirements were 89 500 kWh for the arched greenhouse and 94 400 kWhfor the sawtooth greenhouse. In comparison with the reference greenhouse, the heat requirement wasaround 200 kWh per m2 and year less in the simulated greenhouses. Furthermore, it was found thataround 31 800 kWh of cooling is required over the year (249 kWh per m2 and year) for the archedgreenhouse and 30 900 kWh per year (241 kWh per m2 and year) for the sawtooth greenhouse, to keepthe indoor temperature at 20 °C. Moreover, two to three possible harvests annually gives the yield of 3456-5184 kg tomatoes per year. Both the simulated greenhouses are feasible concepts, however thesawtooth greenhouse is a better option due to its increased longevity and lower contribution ofgreenhouse gas emissions over time. Furthermore, more research needs to obtain a fully closed cycle.
6

Potencial do extrato pirolenhoso da madeira de eucalipto como agente conservante de cosméticos e saneantes / Potential of pyroligneous extract of eucalyptus wood as a preservative of cosmetic and sanitizing products

Almeida, Raquel Silveira Ramos 04 June 2012 (has links)
O extrato pirolenhoso é uma substância orgânica resultante da condensação da fumaça gerada durante a carbonização da madeira ou de outras fontes de matéria-prima vegetal, sendo constituído por, pelo menos, 80% de água e dezenas de compostos, dentre os quais se incluem substâncias fenólicas, aldeídos e ácidos orgânicos. Portanto, não seria utópico supor-se que nessa gama de compostos possam estar incluídas substâncias que apresentem propriedades conservantes para aplicações na área cosmética e de saneantes. É nessa direção que se avaliou o potencial de utilização do extrato pirolenhoso da madeira de eucalipto. Especificamente, houve a intenção de se estudar as características e propriedades do extrato pirolenhoso obtido dessa madeira levando-se em conta duas fontes distintas; avaliar em particular suas propriedades antifúngicas, e as possibilidades do uso do extrato pirolenhoso como conservante, na substituição de ingredientes como, por exemplo, o formaldeído, ainda hoje utilizado na indústria em formulações de produtos cosméticos e atualmente proibido em produtos saneantes, segundo nova resolução RDC 35/08 da ANVISA. Os compostos químicos presentes am ambos os extratos foram identificados mediante análises em cromatógrafo acoplado a espectrômetro de massa (GC/MS). De forma geral, as análises dos extratos demonstraram a presença de uma gama de compostos oxigenados, tais como ácidos carboxílicos, ésteres, éteres e cetonas. Além disso, foram detectados fenol, guaicol e derivados fenólicos. O produto que apresentou o melhor potencial antifúngico foi o extrato pirolenhoso de uma das fontes estudadas. / Pyroligneous extract is an organic substance resulting from the condensation of the smoke generated during the carbonization of wood or other vegetable raw material, consisting of at least 80% of water and many compounds including: phenolic substances, aldehydes and organic acids. It would not be utopian, therefore, to assume that, in this gamma of compounds there could be substances having preservative properties for cosmetic and sanitizing products. This study evaluates the potential of the pyroligneous extract of eucalyptus wood. Specifically, the characteristics and properties of the pyroligneous extract from eucalyptus wood from two distinct sources; to evaluate in particular its antifungal proprieties and the possibility of using the pyroligneous extract as a preservative. This would substitute, for example, the formaldehyde currently used in the cosmetic industry. In fact formaldehyde has now been forbidden in sanitizing products; resolution RDC 35/08 of ANVISA. The chemical compounds of both extracts were identified by analyses of a gaseous chromatograph connected to the mass spectrometer (GC/MS). In general, the analysis of extracts demonstrated the presence of oxygenated components gamma such as carboxylic acids, esters, ethers and ketenes. Moreover, phenol, guaicol and phenol derivatives were detected. The product that showed better potential antifungal results was the pyroligneous extract from one of the studied sources.
7

The distortionary effect of production sharing contract in upstream petroleum industry

Moridifarimani, Fazel January 2018 (has links)
There is a vast literature on the distortionary effects of the tax-royalty system, while the effects of Production Sharing Contract (PSC) is largely understudied. Moreover, economic studies typically oversimplify the physics of the field and consequently end up with models which do not necessarily fully reflect the reality. In this study, we build a dynamic optimisation model which nests the physics of the reservoir and investigates the distortionary effects of a PSC.
8

Potencial do extrato pirolenhoso da madeira de eucalipto como agente conservante de cosméticos e saneantes / Potential of pyroligneous extract of eucalyptus wood as a preservative of cosmetic and sanitizing products

Raquel Silveira Ramos Almeida 04 June 2012 (has links)
O extrato pirolenhoso é uma substância orgânica resultante da condensação da fumaça gerada durante a carbonização da madeira ou de outras fontes de matéria-prima vegetal, sendo constituído por, pelo menos, 80% de água e dezenas de compostos, dentre os quais se incluem substâncias fenólicas, aldeídos e ácidos orgânicos. Portanto, não seria utópico supor-se que nessa gama de compostos possam estar incluídas substâncias que apresentem propriedades conservantes para aplicações na área cosmética e de saneantes. É nessa direção que se avaliou o potencial de utilização do extrato pirolenhoso da madeira de eucalipto. Especificamente, houve a intenção de se estudar as características e propriedades do extrato pirolenhoso obtido dessa madeira levando-se em conta duas fontes distintas; avaliar em particular suas propriedades antifúngicas, e as possibilidades do uso do extrato pirolenhoso como conservante, na substituição de ingredientes como, por exemplo, o formaldeído, ainda hoje utilizado na indústria em formulações de produtos cosméticos e atualmente proibido em produtos saneantes, segundo nova resolução RDC 35/08 da ANVISA. Os compostos químicos presentes am ambos os extratos foram identificados mediante análises em cromatógrafo acoplado a espectrômetro de massa (GC/MS). De forma geral, as análises dos extratos demonstraram a presença de uma gama de compostos oxigenados, tais como ácidos carboxílicos, ésteres, éteres e cetonas. Além disso, foram detectados fenol, guaicol e derivados fenólicos. O produto que apresentou o melhor potencial antifúngico foi o extrato pirolenhoso de uma das fontes estudadas. / Pyroligneous extract is an organic substance resulting from the condensation of the smoke generated during the carbonization of wood or other vegetable raw material, consisting of at least 80% of water and many compounds including: phenolic substances, aldehydes and organic acids. It would not be utopian, therefore, to assume that, in this gamma of compounds there could be substances having preservative properties for cosmetic and sanitizing products. This study evaluates the potential of the pyroligneous extract of eucalyptus wood. Specifically, the characteristics and properties of the pyroligneous extract from eucalyptus wood from two distinct sources; to evaluate in particular its antifungal proprieties and the possibility of using the pyroligneous extract as a preservative. This would substitute, for example, the formaldehyde currently used in the cosmetic industry. In fact formaldehyde has now been forbidden in sanitizing products; resolution RDC 35/08 of ANVISA. The chemical compounds of both extracts were identified by analyses of a gaseous chromatograph connected to the mass spectrometer (GC/MS). In general, the analysis of extracts demonstrated the presence of oxygenated components gamma such as carboxylic acids, esters, ethers and ketenes. Moreover, phenol, guaicol and phenol derivatives were detected. The product that showed better potential antifungal results was the pyroligneous extract from one of the studied sources.
9

Algoritmo de colônia de formigas e redes neurais artificiais aplicados na monitoração e detecção de falhas em centrais nucleares / Ant colony optimization and artificial neural networks applied on monitoring and fault detection in nuclear power plants

SANTOS, GEAN R. dos 11 November 2016 (has links)
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-11-11T09:45:23Z No. of bitstreams: 0 / Made available in DSpace on 2016-11-11T09:45:23Z (GMT). No. of bitstreams: 0 / Um desafio recorrente em processos produtivos é o desenvolvimento de sistemas de monitoração e diagnóstico. Esses sistemas ajudam na detecção de mudanças inesperadas e interrupções, prevenindo perdas e mitigando riscos. Redes Neurais Artificiais (RNA) têm sido largamente utilizadas na criação de sistemas de monitoração. Normalmente as RNA utilizadas para resolver este tipo de problema são criadas levando-se em conta apenas parâmetros como o número de entradas, saídas e quantidade de neurônios nas camadas escondidas. Assim, as redes resultantes geralmente possuem uma configuração onde há uma total conexão entre os neurônios de uma camada e os da camada seguinte, sem que haja melhorias em sua topologia. Este trabalho utiliza o algoritmo de Otimização por Colônia de Formigas (OCF) para criar redes neurais otimizadas. O algoritmo de busca OCF utiliza a técnica de retropropagação de erros para otimizar a topologia da rede neural sugerindo as melhores conexões entre os neurônios. A RNA resultante foi aplicada para monitorar variáveis do reator de pesquisas IEA-R1 do IPEN. Os resultados obtidos mostram que o algoritmo desenvolvido é capaz de melhorar o desempenho do modelo que estima o valor de variáveis do reator. Em testes com diferentes números de neurônios na camada escondida, utilizando como comparativos o erro quadrático médio, o erro absoluto médio e o coeficiente de correlação, o desempenho da RNA otimizada foi igual ou superior ao da tradicional. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
10

Zum Einfluss von Witterung und Klima auf den Landschaftszustand und die Landschaftsentwicklung im Uvs-Nuur-Becken (NW-Mongolei)

Barsch, Andreas January 2003 (has links)
Im Landschaftszustand und in der Landschaftsentwicklung kommen funktionale Beziehungen zwischen dem naturbedingten Energie-, Wasser- und Stoffhaushalt einerseits und den Auswirkungen der Landnutzung andererseits zum Ausdruck. Gegenwärtig verändert der globale Anstieg der bodennahen Temperaturen vielerorts den landschaftlichen Energie-, Wasser- und Stoffhaushalt, wobei besonders in Trockengebieten zu erwarten ist, dass dieser Trend in Verbindung mit einer unangepassten Landnutzung das Regenerationsvermögen der Vegetation einschränkt und zur Zerstörung der Bodendecke führt.<br /> <br /> Für die Mongolei und für benachbarte Gebiete Asiens sind in Szenarien zur globalen Erwärmung hohe Werte des Temperaturanstiegs prognostiziert worden. Eine globale Einschätzung der anthropogen induzierten Bodendegradation hat diese Region als stark oder extrem stark betroffen eingestuft. Vor diesem Hintergrund wurde im Uvs-Nuur-Becken, das im Nordwesten der Mongolei und damit in einer der trockensten Regionen des Landes gelegen ist, untersucht, wie sich der globale Temperaturanstieg auf der lokalen und regionalen Ebene widerspiegelt und wie der Landschaftshaushalt dabei verändert wird.<br /> <br /> Die Auswirkungen des sommerlichen Witterungsverlaufes auf den Landschaftszustand sind 1997 bis 1999 an einem Transsekt erfasst worden, das sich zwischen dem Kharkhiraa-Gebirge am Westrand des Beckens und dem See Uvs Nuur im Beckeninneren von den Polsterfluren und Matten der alpinen Stufe über die Gebirgswaldsteppe, die Trockensteppe bis zur Halbwüste erstreckt. An neun Messpunkten wurden witterungsklimatische Daten in Verbindung mit Merkmalen der Vegetation, des Bodens und der Bodenfeuchte aufgenommen. Die im Sommer 1998 gewonnenen Messwerte wurden mit Hilfe einer Clusteranalyse gebündelt und verdichtet. Auf dieser Grundlage konnten landschaftliche Zustandsformen inhaltlich gekennzeichnet, zeitlich eingeordnet und durch Zeit-Verhaltens-Modelle (Stacks) abgebildet werden. Aus den Zeit-Verhaltens-Modellen wird ersichtlich, dass man Zustandsformen, in denen die Hitze und die Trockenheit des Sommers 1998 besonders stark zum Ausdruck kommen, an allen Messpunkten beobachten kann, nimmt man die Station auf dem fast 3.000 m hohen Gipfel des Khukh Uul sowie die grundwasserbeeinflusste Station in unmittelbarer Seenähe aus. In ihrer extremen Form sind Trockenperioden jedoch nur im Beckeninneren und am Fuß der Randgebirge, also in der Halbwüste, in der Trockensteppe und in der Wiesensteppe aufgetreten. Im Bergwald sowie im Bereich der alpinen Matten und Polsterfluren fehlen sie.<br /> <br /> Am stärksten sind die grundwasserfreien Bereiche der Halbwüste von der Hitze und Niederschlagsarmut des Sommers 1998 betroffen. An vier Fünfteln der Tage des Beobachtungszeitraumes herrscht an diesem Messpunkt extreme Trockenheit. Es fällt entweder gar kein Niederschlag oder nur so wenig, dass der seit dem Frühjahr erschöpfte Bodenwasservorrat nicht aufgefüllt wird. Das Verhältnis zwischen Niederschlag und potenzieller Verdunstung liegt hier bei 1:12.<br /> <br /> In der Halbwüste zeichnet sich eine fortschreitende Desertifikation ab, zumal hier eine nichtangepasste Weidenutzung dominiert, in der Ziegen eine immer größere Rolle spielen. Dies gilt insbesondere für Bereiche in Siedlungsnähe. Örtlich ist auch der Bestand der Trockensteppe gefährdet, die sich an die Halbwüste zum Beckenrand hin anschließt. Hier ist nicht nur die Viehdichte am höchsten, sondern hier werden auch die meisten unbefestigten Fahrwege wild angelegt und die Bodendecke damit zerstört. Dies kann im Endeffekt zu einem Übergreifen von Prozessen der Desertifikation führen.<br /> <br /> Aus methodischer Sicht zeigt sich, dass die Kennzeichnung landschaftlicher Zustandsformen durch Zeit-Verhaltens-Modelle die Ermittlung der Auswirkungen von Witterung und Klima auf den Landschaftszustand erleichtert, da sie deren Aussage konzentriert. Zur Interpretation der Ergebnisse ist jedoch ein Rückgriff auf die beschreibende Darstellung der Messwerte notwendig. Die im westlichen Uvs-Nuur-Becken und seinen Randgebirgen angewandte Verfahrensweise ermöglicht es, globale Aussagen zur globalen Erwärmung der Kontinente regional oder lokal zu überprüfen und zu untersetzen." / Landscape condition and landscape development express the functional relations between energy balance, water balance and material balance on the one hand and on the other hand they reflect the effects of land use. At present the global increase of near-surface air temperature changes the energy balance, water balance and material balance in many places. Especially in arid regions this trend and an inappropriate land use restrict the regeneration ability of vegetation and lead to the degradation of soil cover.<br /> <br /> Different scenarios for global warming prognosticate high values of increasing air temperature in Mongolia and its adjacent regions in Asia. A global estimation of anthropogenicly induced soil degradation classifies this region as strongly or extremely strong affected. Against this background a research was carried out in the Uvs Nuur Basin, placed in the northwest of Mongolia and therefore in one of the most arid regions of this country. The object of investigation was the reflection of the global increase of air temperature on a local and regional level and the resulting changes of landscape balance.<br /> <br /> From 1997 to 1999 the effects of changes in summer weather on the landscape condition were measured on a transect from the Kharkhiraa mountains at the western margin of the basin up to the lake Uvs at the centre of the basin. The transect included alpine mat, mountain steppe, dry steppe and semi desert. Climatic data was collected at 9 transect stations, in addition with characteristics of vegetation, soil and soil moisture. The data of summer 1998 was bundled and consolidated with a cluster analysis. On this basis forms of landscape condition could be evaluated in content, arranged chronologically and characterised by time performance models (stacks).<br /> <br /> The time performance models prove that forms of landscape condition marking the heat and the drought of summer 1998 can be found at every station of the transect except of the one on the summit of Khukh Uul at almost 3.000 m above sea level and another groundwater-influenced station at the bank of lake Uvs. However, extremely dry periods occur only from the centre of the basin up to the foothills, thus in the semi desert, the dry steppe and the short grass steppe. They do not occur in the mountain forest and in the alpine mat.<br /> <br /> Areas in the semi desert are most affected by drought and lack of precipitation during the summer 1998. Four fifths of the days in the measurement period are extremely droughty days. Either there is no precipitation at all or it is insufficient to fill up the soil water storage exhausted since spring-time. The relation of precipitation and potential evaporation averages out here at 1:12.<br /> <br /> A progressive desertification becomes apparent in the semi desert, particularly determined by an inappropriate land use in conjunction with an increasing goat-rearing in the area around the settlements. Partially this trend even affects the dry steppe in adjacency to the semi desert toward the margin of the basin. These areas are characterised not only by the highest stocking rate but also by the largest number of unofficial dirt roads thus leading to the denudation of the soil cover and finally to the spreading of desertification processes.<br /> <br /> From the methodical point of view it is obvious that the characterisation by time performance models facilitates the determination of weather and climate influence on landscape condition by summarising their information. However, the interpretation of the results has to be accomplished by a describing analysis of the measured data. The procedure applied in the western Uvs Nuur Basin and its adjacent mountains provides the opportunity to examine and substantiate the reports on global warming at regional or local level.

Page generated in 0.0896 seconds