Global ETD Search
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 69 for “"gas concentrations"”.
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Measurement of Dissolved Gas Concentrations in Natural Waters Utilizing an In-Situ, Membrane Inlet, Linear Quadrupole Mass Spectrometer
… ship's cables to monitor a suite of dissolved gases and volatile organic compounds in saltwater and freshwater environments. Spectrometer data in Lake Maggiore, Florida were acquired at a rate of 0.7-3.6 seconds/sample for 2-3 hours. The resulting multi-analyte spectrometer data were recorded …
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Predicting toxic gas concentrations resulting from enclosure fires using the local equivalence ratio concept linked to fire field models
… A main component of fire effluent are toxic gases and one of the main toxic gases responsible for a significant number of fire fatalities is Carbon Monoxide (CO). Current engineering fire field models either ignore the prediction of toxic gas generation or require the use of detailed …
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Vergleich der Arbeitsplatzbelastung während einer Xenon- oder Lachgasanästhesie
The aim of this study was to compare waste gas concentrations during xenon or nitrous oxide anaesthesia. A total of 64 patients were included in this study. Gas concentrations were measured with a mass spectrometer during anaesthesia. The probes were taken beside the patient's head and thorax and …
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Experimentelle und mathematische Modellierung der Festbettvergasung am Beispiel der Gleichstromvergasung von Holzhackschnitzeln
… and mathematical modelling of moving-bed-gasification was to increase the transparency of the process. At Dresden University of Technology a gasifier with a high number of measuring points was used. Two-dimensional profiles of temperature and gas-concentrations were analysed. Samples of …
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Carbon dioxide transfer through hollow fiber membranes
… that included a prediction of the internal axial gas concentrations within the fiber lumen. This model was validated by measuring bulk gas velocity within fiber lumen. A trend of increasing mass transfer coefficients with internal pressure was observed. A correlation for predicting this effect was …
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Studies of Mixing Processes in Gases and Effects on Combustion and Stability
… models of laminar mixing of initially separated gases are studied. Two models study the effects of the mixing dynamics on the chemical reactions between the gases. The third model studies the structure and stability of a laminar mixing layer in a binary gas. The three models are:</p> <p>1. Two …
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Physics Guided Machine Learning algorithm for MAX-DOAS retrieval
… extinction coefficient profiles and trace gas concentrations. The ill-posed nature of the MAX-DOAS inversion problem makes it almost impossible to design an inversion algorithm providing a definite solution. A possible way to find a low-error inversion algorithm is incorporating the machine …
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Trade and the environment : the political economy of CO₂ emission leakage with analysis of the steel and oil sands industries
… observed increase in anthropogenic greenhouse gas concentrations." The IPCC Fourth Assessment states that humans have "more likely than not" contributed to the phenomena of more frequent "warm spells/heat waves," larger "area[s] affected by droughts," more "intense tropical cyclones.. .and …
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A comparative study of the ventilatory responses of the golden hamster, Mesocricetus auratus and the laboratory rat, Rattus norvegicus, under hypercapnic and/or hypoxic gas mixtures
… auratus</i>) to different ambient respiratory gas concentrations with those of the white rat (<i>Rattus norvegicus</i>). Total body plethysmography was used to measure tidal volume (V<sub>T</sub>), respiratory frequency (R<sub>f</sub>), and minute volume (V<sub>E</sub>). The respiratory gases …
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An experimental study of forced ventilation glovebox fires
… since glovebox failure may allow hazardous gases to escape containment. A full scale mockup of a glovebox and corresponding air flow system was constructed. Careful consideration was given to the two components expected to cause glovebox failure: the gloves and windows. In addition to normal …
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Applications of thermophysical characterization using the 3-omega technique
… in this dissertation. Using experiments on gas mixtures, a gas sensing technique is developed that can determine gas concentrations in binary mixtures based on their thermophysical properties. This is demonstrated using two sensor geometries with sensitivities comparable to other …
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Environmental Changes in Eastern Lapland during the last 50 years
… composition, are the atmospheric anthropogenic gas concentrations of CO, NOx, O3 and SO2. SO2 is also used in a proxy to estimate H2SO4 concentrations. Decreasing long-term trends are found for CO, NOx, SO2 and H2SO4. The decreasing emissions from Kola peninsula, is the cause for long-term …
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Group III-nitride devices and applications
… on GaN are developed for use in high temperature gas or chemical sensor applications. To increase device sensitivity, while maintaining a simple one-step photolithography fabrication process, devices were designed to operate at high harmonic frequencies. This allows for GHz regime operation …
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Effects of Downwash when Measuring Gas Concentration with UAV-Mounted Gas Sensors
… to cause significant changes in density-based gas concentration measurements. US regulations evaluate gas concentration as a function of gas density, and accurate concentration measurements are critical for protecting health and safety, which means evaluation of actual downwash effects on …
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Entwicklung eines langzeitstabilen Niedrigenergie-IR-Gassensors
… reduce the power-consumption of an infrared-gas-sensor (IR) are introduced. By using the maximum of the sensor-signals first derivative, the author was able to reduce the power-consumption of an carbon-dioxide-sensor (CO2) for ventilation control by a factor greater than 200, in comparison to …
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Estimating the likelihood of significant climate change with the NCAR 40-member ensemble
Increasing greenhouse gas concentrations are changing the radiative forcing on the climate system, and this forcing will be the key driver of climate change over the 21st century. One of the most pressing questions associated with climate change is whether certain aspects of the climate system will …
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The effect of soybean oil in starter diets on nursery air quality and performance of weanling pigs
… air quality was evaluated by measuring the concentrations of ammonia, carbon dioxide, settled dust, suspended particle size, and by microbiologically culturing air samples. Weekly performance data was also collected. ADG was unaffected by dietary treatment. ADFI was increased when soybean …
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Mechanisms and management for soil carbon sequestration
… for mitigating the rising atmospheric greenhouse gas concentrations as well as for maintaining the fundamental services that soils provide to humanity. Many of the mechanisms involved in accruing and storing soil C are not entirely clear, and factors like litter chemistry and minerology can all …
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Patterns of soil maturation and mixing at the Apollo 16 landing site: surface soils
… for major element chemistry and trapped inert gases are assembled from the literature and used to infer the provenance of archetypical soils and kinship relationships of remaining surface samples. The hypothesis of maturation domination of inert gas variations is considered and its consequences …
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Reduction of ammonia emissions by applying a urease inhibitor in fattening pig houses
… slurry storage. In addition to ammonia concentrations, the gas concentrations of carbon dioxide, methane and nitrous oxide and odour emissions were measured. The reduction effect was calculated using four different calculation approaches based on the case-control principle: a linear …
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