Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1981. / Microfiche copy available in Archives and Science. Film reel in Science Library. / Bibliography: leaves 79-80. / by Peter John Vrolijk. / M.S.

The major objective of this study was to determine the relations between certain electrical parameters (resistance, capacitance) and mechanical parameters (stress, strain) for carbon black loaded rubber. Resistance and capacitance were measured under constant strain and constant stress conditions in an effort to determine these relations for rubber filled with 30 to 70 parts carbon black per hundred parts rubber. Seven materials for making electrical contact were investigated. Silver paint was found to result in low contact resistance, to be reliable, and fairly inexpensive. Electrical parameters (resistance, capacitance) and mechanical parameters (stress, strain) were found to exhibit similar trends as functions of carbon black content. This is in agreement with previous theories of the conduction network and electron percolation. Resistance and stress relaxation equations were quantitatively determined. These follow a power law time dependence, with relaxation rates depending mainly on carbon black content and temperature. / M.S.

The assumption of a fixed base condition for the analysis of wall stresses is justified only in the case of a rigid support, when the fixed-end moment is small. By evaluating the constants of the deflection equation for the wall at any given point, the variation of stress along the wall and the rotation of the base can be determined. It should be noted that for larger values of x, when the effect of the (Bx)-functions begins to die out, the constants become more dependent on any slight variation of the observed stress. Thus, a choice of several readings would have been desirable in the region where x does not exceed the value of 3λ/2. Strain readings at higher points serve mainly to test their relative accuracy and as a check on the B-value, but not to determine the constants. A comparison of stresses along the floor would be extremely difficult, if not meaningless, since one would have to depend on the mechanical accuracy of the model in order to evaluate the boundary conditions for the floor. A direct analysis of the floor stresses is not advisable in the case of a small model, since irregularities in the manner of support influence these stresses greatly. The theoretical approach to stress-evaluation for the bottom plate resting on a rigid foundation, has been discussed by R. Hofmann (9) for the particular case where Poisson’s Ratio is equal to zero. No derivation of formulas has been given in the paper. / Master of Science

The program described in this paper is capable of determining horizontal and vertical shear resultants at any point within a one, two, or three plate system where plates are joined at ninety degree angles. Program options allow for tapered walls and combinations of both uniform and triangular loads for each type plate problem. The three plate solution process automatically imposes boundary conditions conducive to one quarter of a monolithically constructed rectangular tank system due to tank symmetry. The plate dead weight effects and their associated shear force upon the floor plate are also accounted for when analyzing the three plate problem. Difficulties are encountered in the refinement of plate finite element meshes due to program computer storage requirements. The result is that derived resultant values do correlate with published solutions for one or two plate problems. Three plate problems require at least an 8x8 plate mesh, 8.7 megabits computer storage, to provide acceptable resultant accuracy. / Master of Science

Master of Science

A field study was conducted at a residence in Chesapeake, Virginia to determine the effect of setback distances from a drainage ditch on the disposal of septic tank effluent. The study was done from September 1979 to August 1981. The soil used is the Tomotley series belonging to the fine-loamy, mixed, thermic family of Typic Ochraquults. Four prototype trenches were installed at 1.5, 3, 6 and 21 m from the edge of a drainage ditch which was 1.5 m deep. The trenches were pressure dosed equally with 2.4 to 4 cm per day. Replicated nests of sampling wells at depths 90, 150 and 300 cm were placed with distance from the trenches. Continuous stage recorders were positioned 4.5, 29.1 and 60 m from the ditch to monitor water table behavior. Groundwater analysis included fecal coliforms, the NH₄, NO₃, NO₂, Na, Ca, Mg, Cl and PO₄ ions, pH and EC. Ammonium concentrations in the soil beneath the trenches indicated nonuniform effluent infiltration yet more uniform than with conventional gravity flow distribution. High sodium absorption ratios of the septic tank effluent ranging from 18 to 45 did not significantly reduce infiltration rates as no ponding of effluent in the trenches was observed. The existing land surface was sloped greater than the water table gradient resulting in decreasing unsaturated depths with closeness to the ditch. The mean distances between the trench bottom and the water table were 64 cm at 3 m, 80.1 at 6 m and 90.4 cm at 21 m. The accumulation of fecal coliforms, NH₄, P, Cl and total salts (EC) in the groundwaters at 120 to 150 cm depth was inversely proportional to the mean distances from the trench bottoms to the water table. The lack of denitrification occurring underneath the trench with the most extensive unsaturated zone suggests NO₃ may accumulate under disposal systems that have mean unsaturated depths of ≥ 90 cm. Effluent movement was mainly lateral and in the upper zone of the water table with limited vertical movement below the water table surface. An equation applying D-F theory to infinitely deep soil was developed to describe flow for the given drainage system and for the inclusion of standard size drain fields. The current practical setback distance of 21 m is considered counterproductive for effluent treatment for some situations. / Ph. D.

O trabalho propõe procedimentos para a avaliação da degradação mecânica de reservatórios de polietileno para água potável expostos às intempéries nas edificações brasileiras. Tais procedimentos envolvem a comparação das propriedades mecânicas antes e após a exposição acelerada de corpos de prova retirados de reservatórios de polietileno em equipamento Weather-OMeter (WOM). Demonstra-se que esses procedimentos reproduzem a degradação provocada pela natureza, por comparação dos resultados obtidos na exposição acelerada até 10 800 horas em WOM com três anos de exposição natural em Piracicaba (SP). / O trabalho propõe procedimentos para a avaliação da degradação mecânica de reservatórios de polietileno para água potável expostos às intempéries nas edificações brasileiras. Tais procedimentos envolvem a comparação das propriedades mecânicas antes e após a exposição acelerada de corpos de prova retirados de reservatórios de polietileno em equipamento Weather-OMeter (WOM). Demonstra-se que esses procedimentos reproduzem a degradação provocada pela natureza, por comparação dos resultados obtidos na exposição acelerada até 10 800 horas em WOM com três anos de exposição natural em Piracicaba (SP).

Thesis (M.S.) -- Mississippi State University. Department of Geosciences. / Title from title screen. Includes bibliographical references.

This thesis focuses on the issue of water tanks especially in the aspect of their functions, maintenance, reconstruction, development and revitalization of tanks. It also deals with the application of reservoirs in agricultural landscape. This thesis contains a description and evaluation of the history and development of tanks in the selected location of South Bohemia, which is the catchment Mladějovický stream. Within the selected and interested area contains a estimate of the economic severity of reconstruction tanks.

O trabalho propõe procedimentos para a avaliação da degradação mecânica de reservatórios de polietileno para água potável expostos às intempéries nas edificações brasileiras. Tais procedimentos envolvem a comparação das propriedades mecânicas antes e após a exposição acelerada de corpos de prova retirados de reservatórios de polietileno em equipamento Weather-OMeter (WOM). Demonstra-se que esses procedimentos reproduzem a degradação provocada pela natureza, por comparação dos resultados obtidos na exposição acelerada até 10 800 horas em WOM com três anos de exposição natural em Piracicaba (SP). / O trabalho propõe procedimentos para a avaliação da degradação mecânica de reservatórios de polietileno para água potável expostos às intempéries nas edificações brasileiras. Tais procedimentos envolvem a comparação das propriedades mecânicas antes e após a exposição acelerada de corpos de prova retirados de reservatórios de polietileno em equipamento Weather-OMeter (WOM). Demonstra-se que esses procedimentos reproduzem a degradação provocada pela natureza, por comparação dos resultados obtidos na exposição acelerada até 10 800 horas em WOM com três anos de exposição natural em Piracicaba (SP).