This dissertation presents a generalized analytical study of the whirl instability of a rotating propeller or rotor system. The mathematical model consists of rigid members with three degrees-of-freedom at the wing root and the wing-drive-shaft joints. In addition, each blade has lagging and flapping freedom. Two dimensional aerodynamics, including compressibility and stall effects, are included. Whirl stability boundaries and characteristics are presented. The parameters investigated include both mechanical and operating variations such as shaft stiffness, number of blades and air density. It was found that decreasing forward speed can result in a whirl instability when blade stall is taken into account. No condition was found in which the rotor went into a forward precessional mode of motion. / Ph. D.

The benevolence ethic, a moral formula for successful living which began in the 1660's with a group of low church divines, gained in popularity until it reached its peak of influence in the first half of the eighteenth century. That Henry Fielding, one of the century's most successful novelists, adhered to the ethic and incorporated it in his works is clear from an examination of his journals and his fiction. In his three major novels, Joseph Andrews, Tom Jones and Amelia, Fielding's incorporation of the ethic is evident, and it is his varying use of the ethic in these three novels which contributes heavily to the relative success or failure of each. Fielding's primary vehicle for incorporating the ethic in the novels is a central triangle of characters which reappears in each novel and consists of an older benevolent gentleman, a good-natured young man and a beautiful, innocent and virtuous young woman. His vehicle varies, however, in that each novel focuses on a different member of the triangle, in each the triangle members are interrelated differently and they develop individually in different degrees. In his most successful novel, Tom Jones, Fielding used the ethic as a basic part of the plot. In Joseph Andrews, his first novel, the ethic is blurred by satire, and in his last novel, Amelia, it is distorted with· sentimentalism. / M.A.

A three phase short circuit analysis was performed on an existing industrial distribution system. Justifications and reasons for carrying out such a study are discussed, along with the calculating procedures, assumptions, and techniques. Sample calculations are illustrated, and a complete tabular presentation of maximum fault currents available at all critical locations is given. The study also includes one-line reactance diagrams for the entire system. / M.S.

A red psychrophilic micrococcus (Strain VPI20A) which was isolated from Antarctic Dry Valley soils was used in this investigation to determine the culture's sensitivity to ultraviolet radiation (180 to 300 nm). The spectrum of the typically pigmented culture showed that absorption maxima occurred at 210, 260, 320, 370, 390, 445, 465, 495 and 530 nm, with major maxima at 465, 495 and 530 nm, indicating presence of lycopene or other related compounds. Spectra from a white phenotype which had carotenogenesis suppressed by diphenylamine indicated maxima only in the ultraviolet range (390 nm and below). Comparative sensitivities of red and white cells to ultraviolet radiation were determined with cultures which had been harvested in both log and stationary phases. In the stationary phase, both types of cells had similar mortality curves. The stationary phase cultures were more sensitive than those of the log phase. However, log phase cells had differing death curves, with pigmented cells exhibiting greater resistance to ultraviolet radiation than nonpigmented cells. Addition of amino acids to the growth medium and changes in incubation temperature did not enhance or decrease carotenogenesis, and ascorbate, fluoride, methylene blue, cyanide, azide and glutathione did not affect synthesis of carotenoids in the concentrations used. / M.S.

This work involves the measurement of hybrid- π parameters of a transistor. A simple method of measuring these parameters with reasonable accuracy using available laboratory equipment at frequencies up to 3-MHz is discussed. The results are used to investigate the validity of the measured hybrid- π parameters by experimental measurements performed on the transistor. Various gain functions and output and input resistances are measured, and the results are compared with calculations based on the hybrid- π parameters. / M.S.

Ph. D.

New concepts in linear, time invariant model realization using sensitivity functions are presented. These concepts involve approaching the device modeling problem from an error gradient minimization viewpoint. This leads to the attainment of a minimal index of performance function (IP) and, consequently, emulates a desired device model response either in the frequency or time domain. In the frequency domain the problem of characterizing the AC error gradients for a small signal transistor model is considered. The integral of the weighted squared-error is the IP functional incorporated. It is found that the error gradients all contain a similar expression whose values, when chosen properly, create zero valued gradients and a zero valued (globally minimal) IP functional. Hence a graphical analysis routine based on the similarity expression is developed to provide the advantages listed below: (i) Simplicity. This technique requires no optimization scheme and completely eliminates computer computation costs. (ii) Insensitive model. A design scheme is affixed to the graphical analysis scheme so as to yield insensitive voltage and/or current transfer functions; with respect to drifts in hᵢₑ and hₒₑ transistor parameters. (iii) Basic building block. The small signal model design technique offers a basic building block upon which high frequency model realization techniques, the hybrid pi model for example, can be implemented. In the time domain a variable structure cascaded building block technique was designed and provides among its main features: (i) Simplicity. Although an optimization procedure is required in this technique the circuit analysis program incorporated in the negative gradient algorithm is fixed in terms of the topological structure it must analyse. That is, it need not be updated to calculate new gradient terms for a topologically changing structure as is required by previous variable structure modeling techniques. (ii) Capable of fitting high order responses within a relaxed block by block IP functional. No individual block in the structure may be required to achieve a certain strict IP functional, while the structure in its entirety may achieve the strict functional. (iii) Direct approach. This device modeling technique offers a concise approach to the modeling problem. The design engineer need only know a device characteristic response in order to approach the problem. Further research possibilities include characterization of the AC error gradients for the hybrid pi transistor model and possibly a series, parallel, series-parallel, or parallel-series connection would prove even more beneficial than the cascaded block time domain approach. / Ph. D.

The mycotoxin, aflatoxin B₁, elaborated by the fungus Aspergillus flavus is a coumarin-type compound. This compound has previously been reported in the literature to have an effect on rat liver mitochondria, although the reports are inconsistent. The effect of this compound on oxygen consumption by rat liver mitochondria was examined potentiometrically. All experiments were carried out below the critical micelle concentration of aflatoxin B₁ which was determined in the oxygen electrode solution of Estabrook to be 0.48 mM. Mitochondria were isolated from 80-150 g male Sprague-Dawley derived rats. Aflatoxin B₁ at a concentration of 0. 48 mM was found to inhibit oxygen consumption by 43% in the presence of ADP and by 63% in the presence of DNP. The inhibition brought about by 0.48 mM aflatoxin B₁ occurs when either succinate or β-hydroxybutyrate is used as a substrate. When electrons were fed into the electron transport chain at cytochrome c₁ (or c) using TMPD and ascorbate no inhibition was observed. TMPD, however, released the inhibition brought about by 0.48 mM aflatoxin B₁ in the presence of succinate or β-hydroxybutyrate as substrates. No relief of the inhibition was obtained with menadione. The site of inhibition appears to be between cytochrome b and cytochrome c₁ (or c). The ADP:0 ratio was also depressed by 35% in the presence of 0.48 mM aflatoxin B₁ when NAD-dependent substrates were employed. Mitochondria from protein deficient animals were found to be 42% less sensitive to inhibition by aflatoxin B₁ than mitochondria from protein sufficient animals. The ADP:0 ratio with NAD-dependent substrates was found to be 37% less sensitive in mitochondria from protein deficient animals than in protein sufficient animals. Gregg particles were prepared from mitochondria isolated from protein deficient as well as protein sufficient animals. Both types of submitochondrial particles were found to be more sensitive to aflatoxin B₁ than the whole mitochondria. It was concluded that the inhibition was limited in whole mitochondria by the inner mitochondrial membrane; and in protein deficient mitochondria there is an alteration in the inner mitochondrial membrane which makes aflatoxin B₁ a less potent inhibitor of electron flow. The fact that the inhibition occurs in the presence of DNP as well as ADP indicates that the inhibition is in the electron transport chain and not in the phosphorylating functions ancillary to the chain. DNPstimulated ATPase activity was only slightly affected by aflatoxin B₁ in the absence of reducing substrates. DNP-stimulated ATPase activity was however markedly reduced in the presence of reducing substrate and aflatoxin B₁. This supports the contention that aflatoxin B₁ effects electron transport in the chain and not in the phosphorylating functions ancillary to the chain though some effect is seen there also. / Ph. D.

Sodium borohydride in aqueous dimethylsulfoxide has been shown to be a good reducing agent for converting certain activated aromatic halo-compounds to their corresponding dehalogenated products. The order for ease of removal of the halogen is I>Br>Cl. The activating groups are those that are strongly electron-withdrawing. The reactivity for activating aryl halides substituted with groups such as -NO₂, -CF₃, -F, -Cl, -Br, and -I is in the order ortho > meta > para, thus indicating that the activating effect has its origins in inductive rather than resonance effects. The removal of halogen appears to be occurring via a displacement on-halogen. This has been demonstrated in certain cases by using deuterium oxide instead of water in the reaction. When this is done, the halogen is replaced by deuterium instead of hydrogen. This indicates that the halogen leaves without its bonding electrons, thus leaving a carbanionic site on the aromatic ring. The carbanion is subsequently quenched by a proton from the water. This reaction has also been shown to be applicable to aromatic systems other than benzene. On-halogen type displacement by the hydride ion also occurs on certain polyhalogenated alkanes with the formation of a guasi-carbanionic intermediate which can be quenched by a proton from water, undergo alpha elimination, or undergo beta elimination. The alpha elimination occurs when a good leaving group is not present on the beta carbon. Attempts at trapping the carbene type intermediate from alpha eliminations were unsuccessful, evidently because of the presence of the water in the reaction medium. In two cases eliminations have occurred through a benzene system to generate para-xylylenes. Diazonium salts were also shown to undergo direct reduction with sodium borohydride, thus providing a new route for the deamination of aromatic amines. / Ph. D.

This investigation consisted of a study of the kinetics of propylene disproportionation over a tungsten oxide on silica catalyst. A catalyst of ten percent WO₃ on silica gel (223 square meters per gram B.E.T. surface area) was used in a microcatalytic reactor. Electron probe scans of the commercially prepared catalyst showed that the standard liquid impregnation technique used in preparation of this catalyst can result in large radial variations in the distribution of the promoter within the pellet. Both flow and pulse reactor techniques were used. It had been reported that external mass transfer effects could not be eliminated in this system. Here linear velocities in excess of those used previously were investigated, and it has been found that both external and intraparticle mass transfer effects can be eliminated, though exceptionally high linear velocities are required to eliminate the external mass transfer effects. Initial rate data were obtained for the disproportionation of propylene by this catalyst. Temperatures of 399° to 454° Centigrade and pressures from one to nine atmospheres were used. The experimental data were well correlated by assuming that a Langmuir-Hinshelwood, dual-site surface reaction was the rate controlling step in the reaction mechanism. The mechanism parameters and their temperature dependence were extracted from the experimental data using a linear least squares technique. An apparent activation energy of 24.73 Kcal per mole was found for this catalytic system. During the initial contacting of freshly activated samples of this catalyst with propylene, significant increases in disproportionation activity were observed for periods up to twenty four hours. The rate of catalyst break-in was found to depend on both the temperature and pressure with an activation energy of 47.17 Kcal/mole and a first order propylene partial pressure dependency. Data are presented to establish that both a reduction of the catalyst to WO₂.₉ and the strong adsorption of an olefin are responsible for this period of transient activity. Prior reduction to the normally thermodynamically unfavorable oxidation state of WO₂ was found to give a thirty percent increase in the steady-state activity of this catalyst. The strong adsorption of an olefin was found to be at least partly reversible in an inert atmosphere. / Doctor of Philosophy