Open land has historically been considered an expendable resource. This concept has abetted the sprawl which occurs in all urbanizing areas of our country. With the United States urbanizing at a rate of more than a million acres a year, this concept can no longer be tolerated. In the last fifteen years, urban development has consumed approximately two-thirds as much new land as it did in all the previous years in the history of our country. Virginia has not been an innocent bystander in this process. This thesis points up the necessity for immediate action to preserve open space in the State of Virginia. It examines the human as well as the economic values that can be derived from open space through an analysis of both the active and passive uses to which open space or low-density use lands can be put. This is accomplished through the establishment and critical analysis of the goals and objectives of an open space program for Virginia. The law on open space in Virginia is a mass of detail buried in traditional legal categories developed for other purposes. This thesis has examined the existing constitutional and statutory powers available to local governmental subdivisions for developing an open space program. In addition, it examines and appraises significant proposals for acquiring and controlling open space. From this analysis, alternative programs for open space acquisition and control are presented including the acquisition of development rights, the land bank, fresh concepts of zoning and subdivision regulations, and expanded concepts in the use of the taxing power. / Master of Science

Seasonal population fluctuations of the cottontail rabbit were measured by evening roadside counts and trapping. During the latter part of July, roadside counts showed a rather marked and drastic decline in the number of rabbits. This decline was forecast by the low number of rabbits seen in the field and the low number of rabbits the investigator was able to trap. Further confirmation of this decline came during the first week of the 1960-61 hunting season. A 42 per cent decrease in the number of rabbits killed occurred in spite of a 10 per cent increase in hunting pressure. By the end of the hunting season a 60 per cent decrease in the rabbit harvest was recorded. / Master of Science

The “Symmetrical Complementation Design” which is discussed in this dissertation is intended for those experimental situations where the levels of three factors always sum to the same constant. The levels of the factors, if referred to a common unit of measurement, must be equally spaced. Certain cell entries are omitted to ensure complete interchangeability of the three factors. The usual additive model is assumed. A detailed study about the types of functions which are estimable in this design is presented in the chapter on linear estimation. The study shows that the number of contrasts that can be estimated is limited. For example, the usual linear contrast, which would lead to the hypothesis of equality of effects of all levels of one factor, is not testable in this design. On the other hand, quadratic and higher-order contrasts are estimable for each factor separately. These contrasts are combined into different hypotheses. Estimable functions in one factor only and in two factors are presented for the general case of p levels. There are several methods which can be employed in order to obtain estimates of the treatment effects under various constraints. It must be noted, however, that these estimates are rather meaningless quantities. It is only when they are combined in estimable functions that unique results are obtained. Two methods are described in complete detail; the “high-low” method if only estimation is required, and the "modified high-low” method if both estimation and tests of hypotheses are required. The complete inverse matrix required for this latter method, or a method of obtaining this patterned inverse, is presented. For testing hypotheses, a general technique, based upon the inversion of the matrix in the modified high-low method, is presented. Sums of squares and test statistics are presented for the various hypotheses formulated. Sections are also included which indicate how one might obtain the response for intermediate levels of the factors, and how one might obtain response functions for single factors. A chapter on extensions is presented, where n observations are available per treatment combination. In this connection, three different cases are considered; a) the replications are strictly repetitions of the experiment under otherwise identical conditions. In this case, the analysis proceeds in the customary three-way analysis with n replicates per treatment combination; b) the experiments within a cell represent repetitions over a period of time, during which some kind of trend may be present. In this case the analysis is readily extended into an analysis of covariance; c) the experiments within a cell represent several experiments with the same experimental units, so that the observations within a cell are dependent. On the assumption that the covariance matrix of observations in a cell is the same for every cell, a multivariate analysis can be performed. The problem of estimation is essentially the same in these methods. However different methods are necessary for the testing of hypotheses. Special discussion is also presented for the case where the levels of the factors are not equally spaced; and the case where the model is considered as a mixed model. In conclusion, it has been found that this type of design requires a rather careful consideration of the types of functions that can be estimated and the types of hypotheses that can be tested. Recommendations for interpretation and statement of limitations are made in detail. / Ph. D.

We have undertaken to develop a method !or determining the resonance escape probability of homogeneous reactors containing aqueous solutions of a resonance absorber. TH(NO₃)₄ was selected as a salt since it is readily dissolvable in water. Even at the highest concentration, the atomic densities of thorium and nitrogen are small compared to hydrogen and oxygen. Only the latter two contribute significantly to the slowing down in the high energy range; therefore, a water Monte Carlo serves adequately as the neutron supply to the resonance region of thorium. In order to find an escape probability we determine the ratio of the number of neutrons that attain energies below the resonance region to the number that appear in the resonance region for the first time. The difference between the two numbers in the ratio occurs due to absorption by the resonance absorber, in this case thorium, and due to leakage. The initial source of neutrons comes from H²(d,n)He³ reaction where the deuteron beam strikes the deuterium target at the center of one face of the containing parallelepiped. Once the water Monte Carlo is run one has a set of data cards which can be used as the input data to a second Monte Carlo designed to calculate the resonance escape probability. Our prime concern is this second Monte Carlo. The resonance escape Monte Carlo is a direct analog type using known physical distributions and laws. The decisions about what events occur in the history of a neutron are based on these distributions and laws. The detailed effect of the thorium resonances on the number of neutrons absorbed is described by the cross-section as a function of energy. A Breit-Wigner Doppler broadened single level formulation gives the scattering and absorption parts of the cross-section as a function of energy. Given a neutron-thorium interaction, the neutron is either absorbed or scattered with probabilities σ_ab/(σ_ab+σ_sc) and σ_sc/(σ_ab+σ_sc). A new statistical weight is assigned the neutron by taking the latter fraction of the old weight. A new neutron is picked from the source supply only after the previous neutron has delivered a weight to low energy or to the exterior of the pile. The heart of the Monte Carlo method lies in the determination of a random variable, distributed according to some known probability function. This requires a source of random numbers which in our case is provided by the IBM-650 computer. The resonance escape probability as a function of thorium number density fits very closely to a straight line with small negative slope throughout the whole range of stable concentrations. The Monte Carlo statistics provides probable errors of less than 0.3% for all five points calculated. Each of the five points lies close enough to the straight line of least-squares fit to give an error less than 0.3%. A theoretical determination of the resonance escape probability based on resonance integral theory for the eight peaks used in the Monte Carlo calculation gives good enough agreement to make both methods plausible. Although other resonance escape calculations have been done by the Monte Carlo method, they have been for radically different systems. In all such cases the system was heterogeneous with "lumped" uranium for the absorber. Therefore comparisons between existing Monte Carlo calculations is impossible. We hope to be able to provide experimental verification for the applicability of the Monte Carlo model. / Ph. D.

An investigation was conducted to determine if Sn atoms could be substituted for Si atoms in the compound Cr₃Si. Prom size factor considerations, the feasibility that this substitution should occur seemed reasonable. However, attempts to make the substitution were unsuccessful. A model of the Cr₃O-type compounds, of which Cr₃Si is a representative, is proposed. From this model substitution of a Sn atom for a Si atom would require the formation of a double bond. The possibility of this double bond being unable to form may explain the unsuccessful attempts to make the above substitution. / Master of Science

The problem of determining thermodynamic properties of gaseous systems in which real-gas effects must be considered can be greatly simplified through use of existing ideal-gas theories for the processes of dissociation and ionization. Since, however, the ideal dissociating gas theory neglects ionization effects and the ideal ionizing gas theory does not take into account dissociation, an additional assumption must be made in order to use these two theories within a single system experiencing both effects. The added assumption which is made is that the processes of dissociation, single ionization, and higher levels of ionization all occur independently of one another though in a definite order within the system. With this linearizing assumption of independent gas processes the ideal gas theories then can be applied within their respective ranges of application in order to calculate the thermodynamic properties of any system under equilibrium conditions, provided the ranges of application can be determined. Neither the ideal dissociating gas theory nor the ideal ionizing gas theory explicitly defines the pressure-temperature region throughout which the theory is applicable. In the present work an analytic expression is developed which gives the limiting temperature as a function of pressure for the ideal dissociating gas theory. The method is then generalized in the ionization range so as to provide pressure-temperature boundaries for all levels of ionization within the assumption of independent first-level, second-level, and higher-level ionization processes. / Master of Science

One or more factors which occur in bovine rumen fluid stimulate the growth of a strain of Butyrivibrio. The stimulating material is heat stable, organic in nature and non-dialyzable. It cannot be extracted from rumen fluid with lipid solvents and is retained in part on anion and cation exchange resins. It can be eluted from the resins with strong acid. It is stable to enzymatic hydrolysis by trypsin. Granular mucin or bovine saliva will partially replace the stimulatory activity. The part of the material which was not replaced by mucin did not appear to be any compound that is commonly used to stimulate bacterial growth. The presence of a possible inhibitor for the growth of a strain of Butyrivibrio was demonstrated. / Master of Science

Master of Science

The purpose of this thesis project was to design, construct and evaluate the performance of a high temperature continuous-run electric arc wind tunnel. A pilot model of such a facility was designed assuming that equilibrium air was the working gas. The pilot model facility was constructed and consisted of the following components; arc chamber, stagnation chamber, nozzle section, test and diffusor sections. In the arc chamber, the air passes through the positive column of an electric arc there-by raising its stagnation temperature before entering the stagnation chamber. Also included in the design and construction were water cooling and waste disposal systems, air supply and vacuum systems, and electric arc power supply system and control. An examination of tests performed in the electric-arc facility showed that a low density supersonic flow with a stagnation temperature of approximately 10,000 F could be produced. The power level for this flow was 36 kw; however, with an expected increase of power to 72 kw the stagnation temperature should be raised to 15,000 F. Since no valid technique for measuring temperatures of this magnitude has been perfected to the author's knowledge, these temperatures were calculated according to a method as outlined in the present thesis. The present facility will present an opportunity for study in such topic areas as (1) Aerodynamic Ablation, (2) Magnetoaerodynamic studies and (3) Qualitative studies of chemically reacting gas flows. / Master of Science

The purpose of this investigation was to determine if there was a relationship between the quantity of inhibitor known to diminish the corrosion rate and the potential of a cathodic surface. The potential required to keep a constant current of one milliampere flowing from cathodic corrosion specimens through dilute acid solutions to which one or more known or commercial inhibitors had been added was measured against a saturated calomel reference electrode. Platinum, mild steel, copper, monel, inconel, yellow brass, nickel and tin were used as cathodic specimen electrodes. Platinum was also used as the anode. Four point nine per cent sulfuric acid, five per cent acetic acid and five per cent phosphoric acid were used as electrolytes. / Master of Science