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  • 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

Oxides in the dehydration of Magnesium Chloride Hexahydrate

Kashani-Nejad, Sina January 2005 (has links)
A novel and accurate method of chemical analysis was developed to identify and assay the products of the hydrolysis that occurred when magnesium chloride hexahydrate was heated and held at temperature and reacted with its own liberated waters of hydration. The novel method took advantage of the solubility of magnesium chloride and magnesium chloride hydrates in methanol and the concomitant insolubility of magnesium oxide and magnesium hydroxychlorides in methanol. The method was found to have a precision of 5-7 % and represents a substantial improvement over previous analytical methods. The method is also readily applied to any methanol soluble salt containing insoluble impurities, meaning that it can also be used for the monitoring of the fused salt electrolyte present the magnesium electrolysis cells. [...] / Une nouvelle méthode d'analyse chimique a été développée pour identifier et tester les produits d'hydrolyse qui se forment quand le chlorure de magnésium hexahydrate est chauffé, maintenu à température constante et qu'il réagit avec les eaux d'hydratation qu'il libère. La nouvelle méthode tire avantage de la solubilité du chlorure de magnésium, hydraté ou non, et en parallèle de l'insolubilité de l'oxyde et des hydroxychlorures de magnésium dans le méthanol. Il s'avère que la méthode a montré une précision de 5-7 %, ce qui apporte une importante amélioration aux méthodes analytiques précédentes. La méthode est aussi facilement applicable a tout sel soluble, qui contiendrait des impuretés insolubles, dans le méthanol, ce qui signifie qu'elle peut aussi être utilisée pour le suivi de l'électrolyse de sel fondu présent dans les cellules d'électrolyse du magnésium. [...]
2

Thermal Contraction and Moisture Creep in Concrete.

Chow, David Y.F. January 1953 (has links)
The properties of concrete are being investigated for the last thirty years. Aside from the action of direct load, deformations are produced in concrete by changes in temperature and in moisture content. Concrete, like steel and other structural materials, expands when heated, and contracts when cooled. In general, the coefficient of thermal expansion for concrete is considered to be not much different from that of carbon steel which is 6.5 x 10 -6 per degree F. Therefore, these two materials are assumed to contract or expand together in reinforced concrete structures. [...]
3

Pressure Drop During Evaporation of Water in Tubes.

Yano, George E. January 1953 (has links)
Many flow systems in engineering operations involve the simultaneous transport in pipes of a gaseous (or vapor) phase and a liquid phase. Examples of such systems are numerous; among them are water-steam mixtures in boiler tubes, petroleum liquids and their vapors in tube-stills, liquid-vapor mixtures in refrigeration systems, oil-laden compressed air, condensate return lines, gasoline engine manifolds, partial condensers in fractionation equipment, etc.
4

The physical properties of a Gaspé skarn.

Shih, Tso-min. January 1965 (has links)
This thesis describes the various tests which were carried out on 492 specimens of a Gaspe skarn to determine a number of the physical properties for this particular rock type.[...]
5

A Generalized method for the calculation of supersonic and hypersonic flow behind curved shock waves.

Shih, Lung Yu. January 1964 (has links)
A method of calculating the performance of a hypersonic air intake has been developed. The method is based on the equilibrium flow of a calorically imperfect gas. It is applicable to both axisymmetric and two-dimensional surfaces, the shape of which can be specified by a sixth order polynomial. The method is applicable to both blunt and sharp leading edges. Boundary layer calculations are included. [...]
6

Factors influencing the nitration of polyvinyl alcohol.

Foxlee, Frank Harold. January 1946 (has links)
Note: / The object of tbe investigation was to discover why the nitration of polyvinyl alcohol gave nltrates of highly variable themal stabil1ty. Samples of the comaerolel alcohol were thoroughly purified from soluble, colored impurities and were recovered in e. dry, fibrous form, apparently for the first time. [...]
7

the Mixing of Hot Subsonic Jets with Cold Air Streams.

Chakko, Puthenpurackal Chakko. January 1956 (has links)
A study of the mixing of subsonic jets with cold streams has been made. An apparatus was constructed for the mixing of such jets at angles with streams. Jets with initial temperatures up to 1075 °K were directed at right angle to cold air streams at various velocities and the effects of some of the factors influencing the mixing have been determined and analysed. [...]
8

Compression of Silt Under Model Footings.

Padopulos, Diogenes. January 1957 (has links)
The experimental work described in the thesis consisted of a series of tests of model footings on dry silt of various porosities. It was done from the point of view of settlement-pressure relationship. Also, one of the theories of settlement is examined, and the results of the tests are compared with that theory. The principal factors affecting the tests are pointed out, and suggestions are made to guide further studies of the subject.
9

Study of the Properties and Behaviour of Quartz Crystal Units with Different Drive Level Conditions.

Kahn, Juan P.M.B. January 1956 (has links)
The behaviour of quartz crystal units subjected to high drive levels and prolonged oscillation periods, as well as their subsequent recovery from these two conditions, were investigated. Abnormal oscillatory stresses were found to produce an increase in the internal friction and a consequent decrease in the dynamic modulus of the quartz. These effects appear in the crystal units, as a higher effective resistance and a depressed resonant frequency.
10

Evaluating Interventions in the U.S. Electricity System: Assessments of Energy Efficiency, Renewable Energy, and Small-­‐Scale Cogeneration

Siler-Evans, Kyle 01 August 2012 (has links)
There is growing interest in reducing the environmental and human-­‐health impacts resulting from electricity generation. Renewable energy, energy efficiency, and energy conservation are all commonly suggested solutions. Such interventions may provide health and environmental benefits by displacing emissions from conventional power plants. However, the generation mix varies considerably from region to region and emissions vary by the type and age of a generator. Thus, the benefits of an intervention will depend on the specific generators that are displaced, which vary depending on the timing and location of the intervention. Marginal emissions factors (MEFs) give a consistent measure of the avoided emissions per megawatt-­‐hour of displaced electricity, which can be used to evaluate the change in emissions resulting from a variety of interventions. This thesis presents the first systematic calculation of MEFs for the U.S. electricity system. Using regressions of hourly generation and emissions data from 2006 through 2011, I estimate regional MEFs for CO2, NOx, and SO2, as well as the share of marginal generation from coal-­‐, gas-­‐, and oil-­‐fired generators. This work highlights significant regional differences in the emissions benefits of displacing a unit of electricity: compared to the West, displacing one megawatt-­‐hour of electricity in the Midwest is expected to avoid roughly 70% more CO2, 12 times more SO2, and 3 times more NOx emissions. I go on to explore regional variations in the performance of wind turbines and solar panels, where performance is measured relative to three objectives: energy production, avoided CO2 emissions, and avoided health and environmental damages from criteria pollutants. For 22 regions of the United States, I use regressions of historic emissions and generation data to estimate marginal impact factors, a measure of the avoided health and environmental damages per megawatt-­‐ hour of displaced electricity. Marginal impact factors are used to evaluate the effects of an additional wind turbine or solar panel in the U.S. electricity system. I find that the most attractive sites for renewables depend strongly on one’s objective. A solar panel in Iowa displaces 20% more CO2 emissions than a panel in Arizona, though energy production from the Iowa panel is 25% less. Similarly, despite a modest wind resource, a wind turbine in West Virginia is expected to displace 7 times more health and environmental damages than a wind turbine in Oklahoma. Finally, I shift focus and explore the economics of small-­‐scale cogeneration, which has long been recognized as a more efficient alternative to central-­‐station power. Although the benefits of distributed cogeneration are widely cited, adoption has been slow in the U.S. Adoption could be encouraged by making cogeneration more economically attractive, either by increasing the expected returns or decreasing the risks of such investments. I present a case study of a 300-­‐kilowatt cogeneration unit and evaluate the expected returns from: demand response, capacity markets, regulation markets, accelerated depreciation, a price on CO2 emissions, and net metering. In addition, I explore the effectiveness of feed-­‐in tariffs at mitigating the energy-­‐price risks to cogeneration projects.

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