No description available.

The theory of the formation of surface ice is not fully understood, yet its presence on water surface affects the operation of many different kinds of hydraulic structures. It is known that when the water surface temperature reaches supercooling ice particles are formed at the water surface. If the intensity of turbulence is low these ice particles will be suspended on the surface forming a surface ice. Herein, an experimental study that incorporates the effect of depth, velocity, roughness and air temperature is carried out in a counter-rotating flume to investigate the formation of surface ice in relation to these parameters. The experimental result is supported by a mathematical model based on the theory of formation of surface ice. A mathematical model is developed based on a comprehensive theory and is solved using Matlab. The mathematical model integrates the effect of the heat balance on the water surface with the degree of turbulent mixing and the rate of growth of surface ice. The two calibrating parameters for the model are the magnitude of the initial seeding and the surface heat loss coefficient. The developed mathematical model is calibrated for the different types of surface ice formations for the data obtained from the experiment. The experimental analysis shows that there are four main types of surface ice formations and their formation is mainly dependent on the degree of turbulence. It is also found that the types of these ice formations are dependent on the minimum supercooling temperature at an average depth. Moreover, it is demonstrated that skim ice particles are those ice particles that nucleate on the water surface during low to medium turbulent intensities and can have four different types of shapes, namely needle shapes, finger shapes, hexagonal shapes and irregular shapes. The sizes and relative quantities of these ice particles on the water surface are also dependent on the degree of turbulence.

The theory of the formation of surface ice is not fully understood, yet its presence on water surface affects the operation of many different kinds of hydraulic structures. It is known that when the water surface temperature reaches supercooling ice particles are formed at the water surface. If the intensity of turbulence is low these ice particles will be suspended on the surface forming a surface ice. Herein, an experimental study that incorporates the effect of depth, velocity, roughness and air temperature is carried out in a counter-rotating flume to investigate the formation of surface ice in relation to these parameters. The experimental result is supported by a mathematical model based on the theory of formation of surface ice. A mathematical model is developed based on a comprehensive theory and is solved using Matlab. The mathematical model integrates the effect of the heat balance on the water surface with the degree of turbulent mixing and the rate of growth of surface ice. The two calibrating parameters for the model are the magnitude of the initial seeding and the surface heat loss coefficient. The developed mathematical model is calibrated for the different types of surface ice formations for the data obtained from the experiment. The experimental analysis shows that there are four main types of surface ice formations and their formation is mainly dependent on the degree of turbulence. It is also found that the types of these ice formations are dependent on the minimum supercooling temperature at an average depth. Moreover, it is demonstrated that skim ice particles are those ice particles that nucleate on the water surface during low to medium turbulent intensities and can have four different types of shapes, namely needle shapes, finger shapes, hexagonal shapes and irregular shapes. The sizes and relative quantities of these ice particles on the water surface are also dependent on the degree of turbulence.

No description available.

No description available.

To help establish the surface coordination and organometallic chemistry of palladium electrodes, the chemisorption properties (coverage, orientation, and reactivity) of selected aromatic compounds in aqueous solutions were investigated. Thin-layer electrochemistry was employed with atomically smooth polycrystalline electrodes to extract information on surface packing densities and adsorbate cross sections. Comparison of the latter with calculated values allowed the determination of the more plausible adsorbed-molecule orientations; in a few cases, verification was obtained via surface vibrational (high-resolution electron-energy loss) spectroscopy. Eleven aromatic compounds were studied: [hydroquinone (1), benzoquinone (2), methylhydroquinone (3), 2,3-dimethylhydroquione (4), 2,3,5-trimethylhydroquinone (5), 1,4-dihydroxynaphthalene (6), phenylhydroquinone (7), 2,3-dihydroxypyridine (8), 2,5-dihydroxythiophenol (9), 2-(8-mercaptooctyl)-1,4-benzenediol (10), and hydroquinone sulfonic acid (11)]. For the homoaromatic compounds, chemisorption was oxidative to form surface-coordinated quinones; flat orientations were observed at low concentrations, vertical orientations at much higher concentrations. The presence of substituents more surface-active than the aromatic moiety induced other orientations. Preferential chemisorption was found to increase in the order: phenyl ring < quinone ring < -SH.

Thesis (D.Sc.) -- University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1973.

Thesis (Ph. D.)--Columbia University. / Vita. Bibliographical references included in footnotes.

Thesis (Ph. D.)--Columbia University. / Vita. Bibliographical references included in footnotes.

Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 74-77).