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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 23 for “"CFCs"”.
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Oversampled pipline A/D converters with mismatch shaping
… commutative feedback capacitor switching (CFCS) pipeline design, due to the properties of the CFCS ADC's transfer characteristic, which has reduced differential nonlinearity (DNL) and an even integral nonlinearity (INL). The CFCS converter offers the foundation for the implementation of …
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Modelo en laboratorio de las reacciones de degradación de los CFC'S, HCFC'S y HFC'S en la atmósfera : su relación con la degradación de la capa de ozono y el efecto invernadero
… de la capa de ozono a los clorofluorocarburos (CFCs), comúnmente utilizados en los clásicos aerosoles. Los compuestos CFCs fueron descubiertos en 1920 y contienen cloro, flúor y carbono formando estructuras estables. Durante décadas el uso de los CFCs se mostró tremendamente eficaz y por lo …
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Assessment of the environmental acceptability of refrigerants by discrete mathematics: cluster analysis and Hasse diagram technique
… environmental impact of chlorofluorocarbons (CFCs), mainly used as refrigerants, has lead to look for environmentally acceptable CFC replacements. Main environmental concern CFCs face is their ability to deplete the stratospheric ozone layer, quantified by the ozone depletion potential (ODP). …
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Integrated analysis procedure of aerospace composite structure
… ratio of continuous fiber composites (CFC) makes CFCs one of the most important materials to be introduced in modern aircraft industry. In addition to inherent strength (per given weight) of CFCs, they also offer the unusual opportunity to design the structure and material concurrently. The …
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EXAMINATION OF PHOTOCHEMISTRY AND METEOROLOGY OF ATMOSPHERIC POLLUTANTS FROM THE NORTH CHINA PLAIN
… opportunity to characterize chlorofluorocarbons (CFCs) over a suspected CFC-11 source region in China, finding mixing ratios were well above 2016 global background levels. Based on correlations of CFCs with compounds used in their manufacture, I identify likely source regions of new CFCs …
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Multi-tracer Study for Groundwater Dating in Southern Oman
… tracers were applied, i.e. noble gases, 14C, CFCs and SF6. While radiogenic 4He served as an initial qualitative dating approach, 14C tracer ages were calculated and corrected yielding mean residence times of up to 7000 years. In contrast, tracer ages derived from CFCs and SF6 data ranged from …
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Heat transfer and flow characteristics of condensing refrigerants in small-channel cross-flow heat exchangers
… due to the phase out of chlorofluorocarbons (CFCs), internal volume becomes a key design parameter.
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Sustainable design of hydrocarbon refrigerants applied to the hermetic compressor
… of traditional chlorofluorocarbon refrigerants (CFCs) under the terms of the Montreal protocol. CFCs used in domestic applications were initially replaced with hydrofluorocarbons (HFCs) such as R134a which has a zero ozone depletion potential (ODP). The use of HFCs has also come under scrutiny as …
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Investigación sobre propiedades de nuevos fluidos industriales de bajo impacto ambiental como sustitutivos de gases fluorados para reducción del cambio climático
… a los ampliamente utilizados fluorocarbonos (CFCs, HCFCs, HFCs, PFEs, etc), para su empleo en multitud de aplicaciones como son la refrigeración, limpieza de precisión, fluidos de transferencia de calor, entre otros. Los hidrofluoroéteres (HFEs) se presentan como una buena opción dadas sus …
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A study of North Atlantic ventilation using transient tracers
… tritium 3H), 3He, and the chlorofluorocarbons (CFCs) can be used to constrain the time-scales of the major ventilation pathways for an ocean basin such as the North Atlantic. I present a new global model function, developed from a factor analysis of the WMO/IAEA data set, for predicting the …
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Understanding Drivers of Stratospheric Ozone Change and Fingerprinting its Recovery
… the ocean’s uptake of chlorofluorocarbons (CFCs), particularly emphasizing its influence on recent illicit CFC emissions estimation. Chapter 3 extends this analysis to include ocean uptake and potential microbial degradation processes, evaluating their effects on emission estimates for …
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Fechado de sedimentos marinos para determinar tasas de sedimentación en el Golfo de Fonseca, La Unión, El Salvador
… siglas en inglés), mientras que por el modelo CFCS (flujo constante/sedimentación constante, por sus siglas en inglés) se determinó una tasa de acumulación promedio de 0.324 ± 0.023 g cm-2 año-1 y una tasa de sedimentación promedio de 0.351 ± 0.027 cm año-1. En el núcleo extraído del Golfo de …
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Constraining North Atlantic circulation with transient tracer observations
… by adjusting only initial-boundary conditions of CFCs and tritium, a 1⁰ x 1⁰ offline model and the transient tracer data can be brought into near-consistency, in the domain between 4.5⁰S and 39.5⁰N of the North Atlantic. Constraining a GCM with transient tracers is thus fully practical.
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Constraining the North Atlantic circulation with transient tracer observations
… by adjusting only initial-boundary conditions of CFCs and tritium, a 1° x 1° offline model and the transient tracer data can be brought into near-consistency, in the domain between 4.5°S and 39.5°N of the North Atlantic. Constraining a GCM with transient tracers is thus fully practical. However, …
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Quantifying Stratospheric Chlorine Chemistry by the Satellite Spectrometers GOME and SCIAMACHY
… Due to the fast phase out of the production of CFCs, the increase of the stratospheric chlorine loading could be slowed down, and the recovery of the ozone layer is expected around the year 2050. However, the impacts on atmospheric chemistry, the climate and the biosphere are considerable. By …
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Sustainable development of refrigerator systems using replacement environmentally acceptable refrigerants
… One intriguing aspect is that the chlorine in CFCs is a good lubricating agent and any deterioration of system performance may adversely influence other environmental considerations. Based on the above, the aim of this research is to address the sustainable development of domestic refrigeration …
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Trend Analyses of the Abundances of Atmospheric Molecules
… depleting substances such as chloro uorocarbons (CFCs) to protect the Earth's ozone layer. These halogenated compounds are inert in the troposphere and ultimately converted to HCl in the upper atmosphere. Therefore, by measuring stratospheric HCl concentrations, the effectiveness of the Montreal …
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Trace gases in Antarctic and Greenland firn and ice: a record of carbonyl sulphide and the isotopologues of chlorofluorocarbons
… pathways of the man-made chlorofluorocarbons (CFCs) could help us to mitigate their destructive effect. Previous studies have found that both source and sink processes significantly alter the isotopic composition of trace gases (e.g. N2O and CFC-12). Measuring these changes can be used to …
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Perchlorate Variations Over 300 Years: Influence of Human Activities, Volcanic Eruptions and Bolide Events
… compounds, including chlorofluorocarbons (CFCs), are likely indirectly responsible for approximately two-thirds of the perchlorate present in the current environment. Variations in perchlorate concentrations suggest that natural perchlorate production occurs in the stratosphere and the …
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Investigation on reverse logistics of end of life cars in the UK
… caused by increased levels of carbon dioxide, CFCs, and other pollutants. This has forced government and business to focus on environmental issues on their initiatives where reverse logistics (RL) practice is described as an initiative that plays an important role for those who seek …
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