Engineering Commons^™

Ground- And Excited-State Properties Of Solid Argon Under Pressure, Richard Alan Lesar

Richard Alan Lesar

A self-consistent perturbation model for calculating the ground- and excited-state electronic properties of molecular and rare-gas crystals is presented. A tight-binding approximation is used, in which the effects of the crystal potential, calculated with local-density functionals, are included as a perturbation on the molecules (or atoms). The molecular (atomic) wave functions are then computed from standard Hartree-Fock theory. For the case of solid argon under pressure, a decrease in atomic volume causes a gain in free energy, which is partially balanced by the energy required to compress the atom. Calculated exciton energies for Ar disagree by only 2.5% with experimental …

Polarizability And Quadrupole Moment Of A Hydrogen Molecule In A Spheroidal Box, Richard Alan Lesar, D. R. Herschbach

Richard Alan Lesar

The polarizability and quadrupole moment of a hydrogen molecule enclosed within an infinite-walled spheroidal box are calculated as functions of the hox size, for a range corresponding to nominal pressures up to lo5 kbar. A five-term James and Coolidge variational wave function is employed and the Kirkwood approximation is used for the polarizability. Comparison is made with similar calculations for the H2+ molecule-ion and the II atom, and also with recent density-functional calculations. The box model proves to greatly exaggerate the compression of the H2 bond with pressure but nonetheless yields a realistic correlation of vibrational frequency with internuclear distance. …

The Effects Of Certain Impurities And Their Interactions On Zinc Electrowinning, Donald R. Fosnacht, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

The effects of germanium, antimony, arsenic, cobalt, glue, and free acid concentration were studied on both commercial and synthetic electrolytes. The effects of a single factor and the combined effects of multiple factors were elucidated. The temperature, zinc concentration, and current density were varied for some of the tests. It was found that the acid content was the most critical factor when impurity levels were at normal plant solution concentrations. The ranges where the effect of the impurity became apparent were: greater than 20 ppb (parts per billion) for antimony; 40 ppb for germanium; 120 ppb for arsenic; and 7 …

Method And Apparatus For Making Aligned Flake Composite Wood Material Including Integral Baffles, Gordan P. Krueger, Anders E. Lund, Roy D. Adams

Michigan Tech Patents

A method and apparatus for forming a loosely felted mat of elongated wood flakes mixed with a binder, the mat including a longitudinal axis and the wood flakes being aligned in mutually parallel relation and parallel to the longitudinal axis of the mat. The wood flakes are held in alignment in the mat by a plurality of closely spaced thin planar baffles, the baffles being comprised of a material which can form an integral part of the mat.

Effect Of Refrigerant Charge And Condenser Temperature On The Operating Characteristics Of A Vapor-Compression Air Conditioning System, Ezzat Fikri Assaad

Archived Theses and Dissertations

No abstract provided.

Molded Wood Particle Pallet Having Increased Bending Strength, Bruce A. Haataja

Michigan Tech Patents

The invention includes a molded unitarily formed pallet comprising wood particles bonded together by a cured binder in compressed relation and forming a deck having an upper surface supporting a load, and a plurality of elongated substantially parallel spaced channels supporting the deck. The channels extend from adjacent one edge of the pallet to adjacent an opposite edge. The channels each including spaced channel side walls extending downwardly from said deck and terminating in a planar bottom wall parallel to the deck. The side walls are integrally joined at their upper edges to the deck and integrally joined at their …

Screening Design Test For Cobalt Cementation From Zinc Electrolyte, Mark S. Blaser, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

25th Rocky Mountain Conference

Rocky Mountain Conference on Magnetic Resonance

Abstracts and meeting program from the 25th annual meeting of the Rocky Mountain Conference, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, August 14-17, 1983.

Control Of Oxygen And Carbon Related Crystal Defects In Silicon Processing, P. D. Ownby, P. E. Grayson

Materials Science and Engineering Faculty Research & Creative Works

In the production of silicon articles at an elevated temperature, a stream comprising a controlled mixture of an oxygen-containing first gas and a second gas is admitted to the processing chamber. The first gas is one which partially dissociates under the conditions in the chamber to form both oxygen and the second gas. The second gas is one which is not harmful to silicon at the conditions in the chamber. Substantially equilibrium conditions are established in the chamber so that the dissociation of the first gas to oxygen occurs reversibly. The partial pressure of oxygen (P_O2) is sensed …

Molded Wood Particle Products Including Integrally Joined Intersecting Members, Bruce A. Haataja

Michigan Tech Patents

A molded product formed from wood flakes intermixed with a binder and a first elongated member formed from elongated wood flakes compressed and bonded together with a binder, the wood flakes having a grain direction extending generally parallel to the longitudinal axis of the flakes and the flakes being generally oriented in alignment with the longitudinal axis of the first elongated member. A second elongated member intersects the first elongated member and is integrally joined to it. The second elongated member is also formed from elongated wood flakes compressed and bonded together with a binder, the wood flakes being generally …

Density‐Functional Theory For Solid Nitrogen And Carbon Dioxide At High Pressure, Richard Alan Lesar, R. G. Gordon

Richard Alan Lesar

Structural properties of solid N2 and CO2 under pressure have been studied with a recently reported theory. The model allows for calculation of the structure and dissociation energy of molecular crystals, using no empirical parameters where dispersion energy is included as a sum of the pair interactions. Comparison with available low temperature experimental results shows good agreement with average errors in lattice constants of about 1% and in lattice energies of about 6%. Calculations were performed on nitrogen in a number of structures, including the experimentally observed P a3 (α), P42/m n m (γ), P63/m m c (β), and P …

The Influence Of Additives And Their Interactions On Copper Electrorefining, Chwan-Tsann Wang

Doctoral Dissertations

"Protein colloid (glue), thiourea, Avitone and chloride ion are the most common additives used electrorefining copper. The polarization behavior of these additives, single and combined, was studied by cyclic voltammetry techniques in conjunction with stationary and rotating disc electrodes. In the stationary electrode work, different protein colloids give substantially different results in polarization or interaction with other additives. The role played by Avitone is not clear, but it does somewhat modify other additives in the electrolyte. Thiourea can cause a depolarized peak and a polarized plateau depending on the concentration, the other additives present and the potential selected. Chloride ion …

Development Of Glass Microspheres For Radiotherapeutic Applications, Thomas A. Wetteroth

Masters Theses

"Oxide glasses make excellent candidates for radiotherapeutic microspheres used in liver cancer treatment because of their generally high chemical durability and safety of manufacture. From the compositions containing ~5 wt% P₂O₅ studied, magnesium alumino silicate glass microspheres and magnesium alkali silicate glass microspheres with 4 wt% ZrO₂ had acceptably low releases of both elemental phosphorus in deionized water at 50°C, and radioactive ³²P in human blood plasma at 37°C. The relative ranking of glass compositions in the elemental phosphorus leach test shows good agreement with the rankings of compositions in the radioactive ³²P leach …

Separation Of Mineral Particles In Cyclones Under The Influence Of A Magnetic Field, Kwasi Amoako-Gyampah

Masters Theses

"The separation of mineral particles in a cyclone under the influence of a magnetic field was investigated using an electromagnetic - cyclone arrangement. Feed pulps of dolomite and magnetite were used in the study. Two different cyclone types were investigated: An air-type cyclone arrangement and a conventional cyclone arrangement. Magnetic field strengths of 0 to 3000 gauss (0 - 0.3 Tesla) were used in the study by varying the current through the coils of the electromagnet .

The parameters evaluated in the study were the grades and recoveries of the magnetic concentrates produced, the enrichment ratios, the improvement in recoveries …

Comments On A Paper By Baik And Raj, Hollis P. Leighly

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Twinning Pseudoelasticity In Intl, Manfred Wuttig, Lin Chun-Hung

Materials Science and Engineering Faculty Research & Creative Works

Twin boundaries generally contribute significantly to the damping of a twinned crystal. In an In-19.1 at.% Tl single crystal the damping gives rise to auto modulation if the internal friction studies are performed in the 10 Hz frequency range, with a strain amplitude larger than 0.05 and at temperatures lower than 10°C. The frequency of the auto modulation is about 60 times slower than the frequency with which the reed type sample is driven. The auto modulation frequency has a maximum at -6 C and is characterized by an activation energy of 29 kJ/mol (7 kcal/mol). This maximum can be …

Preface, Delbert E. Day, Günther H. Frischat

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Mechanical Properties Of Alumina For Orthopedic Implant Use, Ho Tong Fang

Masters Theses

"The static fatigue, flexural strength and chemical corrosion of three commercially prepared, polycrystalline aluminas, two of orthopedic implant grade, were measured in demineralized water at 37°C and 70°C. The dissolution of a Ca-rich impurity phase, probably a glass, segregated at the grain boundaries and external surface, appears at least partially responsible for the significant difference in static fatigue of these three aluminas. The present results indicate that the minimum static fatigue in demineralized water, and the highest flexural strength in demineralized water and HF solution are both achieved by the alumina characterized by a low concentration of Ca at the …

Sintering Of Lif-Fluxed Srtio₃, Marie-Christine P. Proudian

Masters Theses

"Lithium fluoride (LiF) is used to enhance the sinterability of perovskites, as it results in the formation of a liquid phase. In this study, the mechanism and kinetics of sintering for LiF-fluxed strontium titanate (SrTiO₃) were investigated. The Sr/Ti ratio was varied between 0.98 and 1.03, and the LiF content in the green compact ranged from 0.5 to 2.0 weight percent. Sintering was conducted at temperatures between 695° and 925°C for isothermal dilatometric shrinkage measurements for time intervals of 6000 seconds or less. Weight loss, shrinkage, density and porosity measurements were conducted on samples isothermally sintered between 690° …

The Effect Of Selected Alloying Elements On The Hardness And Microstructure Of Ductile Cast Iron, Chi-Hua Edward Tseng

Masters Theses

The effects of cooling rate and alloying element on the matrix structure, nodule count and hardness have been studied in this investigation.

Recommendations for producing ferritic ductile iron have been made and the relationship between hardness and pearlite percentage has been obtained in this study.

Glass Formation And Properties In The Gallia-Calcia System, Glenn Whichard

Masters Theses

“The critical cooling rate for glass formation for melts containing from 37.5 to 68.0 mol % Ga₂O₃ varied from 310 ± 80°C/s to 855 ± 115°C/s. The crystallization temperature, microhardness, UV and visible transmission were measured. The density increased from 4.075 g/cm³ at 37.5 3 mol % Ga₂O₃ to 4.402 g/cm³ at 56.0 mol % Ga₂O₃. The refractive index, n_D, increased from 1.778 at 37.5 mol % Ga₂O₃ to 1.802 at 62.0 mol % Ga₂O₃. The IR spectra indicate …

Defect Chemistry Of La-Doped Strontium Titanate, Brian Keith Flandermeyer

Masters Theses

"Thermogravimetric measurements as a function of oxygen activity were performed in the temperature range of 1200°C to 1400°C on a series of La-doped SrTiO₃ compounds. A model postulating the crystallographic accommodation of ionic defects induced by the donor under oxidizing conditions is assumed. Thermodynamic calculations were performed to compare this model to the experimental results with reasonable success"--Abstract, page iii.