Graduation date: 1993

No description available.

Thesis (Ph. D.)--Columbia University, 1930. / Vita. Bibliography: p. 21.

Inaug.-diss.--Leipzig. / Lebenslauf.

The evaluation of groundwater quality has become increasingly important as more industrial waste and solid domestic refuse comes into contact with groundwater. Often the quantity and extent of contamination is determined by direct sampling of the groundwater and soil. An alternative method of detecting contaminated groundwater is by noting the electrical resistivity of the contaminated soil. The feasibility of logging resistivity while conducting cone penetrometer testing has been investigated in this research. To this end a two stage program was devised, consisting of lab testing and then field tests of a working tool. Lab testing was carried out using a prototype probe designed to evaluate the feasibility of the project. The lab testing consisted of determining the resistivity of a number of different soil, electrolyte, and organic contaminant mixtures while varying the configuration of the probe. On the basis of lab testing the necessary requirements for the module dimensions and electronics were chosen and were fine tuned by field tests. The module itself consists of an insulated four electrode array and is mounted behind a standard 15 sq cm piezo-cone (CPTU). Upon completion of the development phase the instrument was tested at four different sites. From field testing it was determined that the resistivity cone (RCPTU) was able to accurately map changes in groundwater chemistry on the basis of resistivity measurements. The results of the resistivity testing were verified by groundwater sampling. It was also found that changes in lithological properties, as determined by the cone penetration test (CPT), could influence the resistivity. Basic guidelines for the use of the RCPTU in contaminant investigations are presented. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

In engineering practice it is important to know which factors affect the thermal and electrical resistance of metal contacts. This thesis is to investigate some of these factors such as surface roughness and contact pressure. Thermal electrical contact resistance ratios for metal contacts were calculated from the experimental data. The technical literature was searched, and several papers were found in which either thermal or electrical contact resistance was studied separately. However, none of the papers recorded data for both thermal and electrical resistances for the same samples. The information found in these papers has been used as a background for understanding the nature of thermal and electrical contact resistance. Both of these contact resistances are primarily a function of the load on the contact and the condition of the surfaces. At low pressures only a small fraction of the total gross area of the contacts is in metal-to-metal contact. Increasing the load, flattens the “hills” and reduces both the thermal and electrical contact resistance. This phenomenon is called “spreading resistance” since the flow of heat or electrical current must spread out after they pass through the restricted areas that are actually in contact. Another type of thermal and electrical resistance, which is called “interface resistance", is caused by a film of foreign material such as an oxide, etc. on the surfaces of the contacting “hills”. If the space between the “hills” of a contact is filled with air, there is a heat flow by convection currents. The literature indicates this quantity of heat flow is approximately one thousandth of the total heat flow through metal contacts. Since the only electrical current conduction mechanism acting between areas not in actual metallic contact is that due to thermionic emission, the electrical resistance for these areas will be extremely high at room temperature for which thermionic emission is negligible. The experimental apparatus to measure both the thermal and electrical contact resistances consists mainly of a bellows-actuated press which is operated remotely under a vacuum bell. The press pressure loads the sample metal wafers. A thin film heat meter is used to indicate the quantity of heat flowing through the metal contacts. The temperature drop caused by the contacts is measured with thermocouples. The temperature difference and the quantity of heat flowing is used to calculate the thermal contact resistance. A strain gage on the bellows-press stem measures the loading on the contact surfaces. Electrical probes are used to measure the electrica1 resistance across the contact surfaces. The thermocouples and electrical resistance probes are permanently installed in the outer two smooth copper wafers. This makes it possible to quickly change to other sets of sample wafers of other metals and finishes. In order to use this permanent arrangement, it is necessary to finish two mating surfaces of the particular set of metal wafers to be tested, similar to the permanent smooth copper wafers so that these two extra mating contact resistances can be found and thus be subtracted from the overall contact resistance. The data indicates that the thermal-electrical contact resistance ratio can be changed by changing the load on the contacts. The heat meter had performed very well, and this new method of measuring heat flow will undoubtedly become a standard method of measuring heat flux.

H.E. Rorschach, Jr. [and] Melvin A. Herlin. / "October 12, 1952." / Bibliography: p. 23. / Army Signal Corps Contract DA36-039 sc-100. Project 8-102B-0. Dept. of the Army Project 3-99-10-022.

The resistivity and thermopower of two series of amorphous alloys have been measured between 4 and 300K. The alloys studied are MgZn and CuZr, both in the largest concentration range available as amorphous materials. The alloys were measured in both the 'as made' and 'relaxed' states, as well as some partial or totally crystallized samples. The simple Ziman theory was found at variance with the experimental results in both cases (even for MgZn, proven to be free-electron like as required by the theory). A simple two component model is proposed as an extreme simplification of the Faber-Ziman theory of liquid metallic alloys. The excellent agreement obtained indicates that metallic glasses should be considered as the alloys they really are. A full Faber-Ziman calculation is performed for CuZr and from this follows the conclusion that the term containing the energy dependence of the pseudo-potential (r), usually assumed to be small, is probably of comparable magnitude to that of the disorder scattering (q). The suggested correlations between the electron-phonon mass-enhancement parameter (lamda) (determined from superconductivity experiments) and the thermopowers are studied and both found not to be valid for CuZr amorphous alloys.

No description available.

Thesis (M.S.)--Ohio University, November, 2005. / Title from PDF t.p. Includes bibliographical references (leaves 126-131)