The neutron diffusion parameters of water and ice were measured by the pulsed source method at two temperatures; 1.0°C. and -19°C. Neutron pulses were obtained at one millisecond intervals by modulating the beam in a Cockcroft-Walton type accelerator. The ₁H³(d,n)₂He⁴ reaction was used to generate neutrons. The samples were contained in cylindrical aluminum cans covered with cadmium. The experiment was conducted inside a large paraffin block which served as a neutron shield and thermal insulator. The temperature of the samples was maintained constant to within ±1°C. Neutrons leaving one surface of the sample were counted in a BF₃ proportional counter. The time distribution of these neutrons was recorded by an eighteen channel time analyzer. The width of each channel was 20 microseconds. The opening of the first channel was delayed 100 microseconds with respect to the start of the neutron burst to minimize harmonics in the neutron decay. A geometric buckling was calculated for each sized sample from B²=[2.405/(R+∈)]²+[π/(H+∈)]² where B² = geometric buckling 2.405 = first zero of J_o Bessel Functions R = radios of cylinder H = height of cylinder ∈ = extrapolation distance The extrapolation distance ∈ was calculated from ∈ =0.71 λ_tr where λ_tr = mean free path of neutrons in water The extrapolation distance was assumed to vary as T^½ where T is the temperature in degrees Kelvin. The measured decay constants, α, were fitted by the method of least squares to a polynomial in B² of the form α = (∑_av) ÷ D_oB² - CB⁴ where ∑_a = the macroscopic absorption cross-section v = the neutron velocity D_o = diffusion coefficient C = diffusion cooling coefficient The resultant values of (∑_av) and D_o for each temperature are below. The data did not permit a determination of C. 1.0°C. (∑_av) = 4595 ± 365 sec⁻¹ D_o = 29600 ± 840 cm²/sec -19°C. (∑_av) = 4355 ± 263 sec⁻¹ D_o = 27050 ± 630 cm²/sec / Ph. D.

This investigation is a study of educational and vocational goals of a selected sample of rural youth and the goals of their parents for them. Factors considered were sex, residence (farm or non-farm), level of living, size of family, and membership in certain rural youth organizations. The sample consisted of 285 ninth and tenth grade rural Virginia students and their parents. The sample was chosen by criteria for selection of youths rather than parents. There were 144 boys and 141 girls; 141 students from farm families, 144 from non-farm; 96 students from “high” level of living, 96 from “middle”, 93 from “low” level of living; 143 students were members of rural youth organizations, 142 were non-members; 142 students were from small families, 144 from large families. Questionnaires relating to educational and vocational goals were administered to the students and their parents. Parents were requested to answer as they hoped their child would answer. The data revealed a statistically significant relationship between place of residence and educational aspirations: non-farm youth had higher aspirations than farm youth. A direct relationship existed between level of living and educational aspirations: the higher the level of living, the higher the aspirations. Students who were not members of the Future Farmers of America, Future Homemakers of America, or the 4-H Club placed a higher value on education than did students who were members of these organizations. Parents from the “middle” level of living group placed the highest value on education; parents from the “low” level of living group placed the least value on the importance of education. / Master of Science

The fundamental definitions of radiative transfer theory are given and the two-dimensional equation of transfer is derived, density of radiation is defined, and two-dimensional two-intensity transfer model is presented. An operational interpretation of the latter model is given interms of military truck transport supply and the functional dependencies of the terms in the transfer equations are evaluated. For this interpretation the density equations are given and the study state and time dependent solutions of the density equations are discussed in polar coordinates. This work was conducted for the U. S. Army Transportation Research Command, Fort Eustis, Virginia, 1961, Task 9R38-11-009-02. / Master of Science

It is the major purpose of this thesis to examine, through a practical engineering problem, the different aspects affecting the development of the structural concept. For this purpose, a prestressed-precast concrete structural system for multi-story construction is developed. After the introductory sections, the development of the structural system is explained in the third section. The section includes an analysis of the system, as well as a description of the individual component of the structure and their interaction. The analysis provides a corroboration of the adequacy of the concepts of the system. Illustration aid in the explanation of the problems involved. / Master of Science

A fast neutron spectrometer was designed and constructed using a proton-recoil telescope. Recoil protons from a thin foil of polyethylene were detected with a silicon surface-barrier diode. The output pulse from the detector is proportional to the energy of the protons and hence the energy of the incident neutrons. The spectrometer was used to obtain pulse height spectra from various sources of fast neutrons including the V.P.I. reactor and the d-d reaction using the Cockroft-Walton accelerator. Results obtained indicate that for high intensity sources the spectrometer is capable of providing high resolution energy spectra although modification is necessary in some cases to reduce background. The compactness of the instrument and its simplicity make it ideal for investigating sources that are not readily amenable to other techniques. / Master of Science

Master of Science

The principal purpose of the study was to determine if the programmed unit on the mathematics of interest, developed by Dr. Harry Huffman, Virginia Polytechnic Institute, could be adapted to the use of high school students at the junior and senior level. To accomplish this objective, extensive revision was necessary. / Master of Science

The electronic analog computer is widely used to simulate most types of automatic control systems, Only a limited amount of work has been reported, however, involving analog computer simulation of sampled-data systems, This is to be expected since such systems are essentially digital in nature. The purpose of the work described in this thesis was to develop methods of simulating various phenomena associated with sampled-data system, The techniques which have been developed are described ad evaluated in the report. In addition, experimental data is presented to illustrate the performance of the various simulation circuits. As an illustration of the techniques which have been developed, the simulation of a representative sampled-data system is described. Data obtained from this simulation is included in the report. / Master of Science

A fifteen day balance study was conducted to test the value of two diets providing 24 and 16 gm. of plant-protein daily and to approach the approximate minimum protein requirement using plant proteins for a 23-month old Chinese girl weighing 12 kg. The diets were supplemented to bring nutrients to the NRC recommended allowances except for protein and calories. Essential amino acids were planned to approximate the FAO provisional pattern. Nitrogen determinations were made on food, urine and feces. Food composites for each diet were analyzed for nine of the essential amino acids using a Beckman/Spince Model 120 Amino Acid Analyzer. Tryptophan was determined by microbiological assay. Nitrogen in the diets averaged 3.96 and 2.69 gm. respectively for the two protein levels of 24 and 16 gm. daily with retention of 0.33 gm. daily for all periods, or 0.48 gm. and 0.44 gm. for the test periods. The essential amino acids as analyzed represent 59 per cent and 34 per eent of the total protein in the moderate and low protein diets. The analyzed amino acid patterns were as follows: tryptophan 1.0 and 1.0; threonine 2.8 and 2.2; isoleucine 5.8 and 3.5; leucine 9.4 and 5.5; lysine 3.1 and 3.7; methionine 1.2 and 0.8; phenylalanine 6.1 and 3.6; valine 6.7 and 3.9; arginine 4.4 and 4.5; and histidine 1.3 and 2.0. A positive nitrogen retention of better than 0.4 gm. daily (0.033 gm./kg.) was obtained with daily nitrogen intake of 0.33 and 0.22 gm. per kg. of body weight for this 23-month old girl with approximately 90 and 84 calories per kg. per day. / Master of Science

The main purpose of this study was two-fold: 1. To show any existing correlation between OBR and UCS tests. 2. To show variation in UCS due to various methods of curing Using a Harvard miniature apparatus, compactive curves were determined for standard AASHO compactive effort for 0, 5, and 10 percent lime. From these curves the moisture contents to be used for strength tests were determined. These were dry of optimum (optimum -6 percent), optimum, and wet of optimum (optimum -̷6 percent). CBR specimens were fabricated at the above moisture contents for 0, 5, and 10 percent line. In all, nine samples were prepared. This was repeated using the miniature apparatus for the unconfined compression test. Six samples were prepared for each test condition. Two of these were tested as molded, two after damp curing (four days 67ºF), and two after oven curing (two days 120ºF). The results of this study indicated the following: 1. Lime increases the strength of the soil. This effect was very significant on the dry side. 2. Up to five percent addition of lime produced little increase in strength. This value may be considered as a fixation value of lime for this soil. 3. Curing increased the UCS and CBR of lime-treated soil. Accelerated oven curing 120ºF for two days given significant increase in strength, especially with 10 percent lime. 4. No definite conclusions could be derived between as molded CBR and as molded UCS, between soaked CBR and damped cured UCS, and between soaked CBR and oven cured UCS. / Master of Science