Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1990. / Includes bibliographical references (leaves 131-134). / by Xiang Chen. / M.S.

The operation and maintenance of a hot-mixed asphaltic concrete plant is a difficult, ill-structured process. In order to maintain an efficient and economical operation, hot-mix plant managers and/or operators need a tool to assist in progressive maintenance and trouble shooting problems associated with the operation of the facility itself and with the quality of the produced mix. In this thesis a preliminary expert system for the operation and maintenance of a hot-mixed asphaltic concrete plant (HMAC plant) was developed. The software developed contains a three-part program. The first is a BASIC program that recommends routine maintenance and inspection procedures for individual plant components. The other two are expert systems developed for trouble shooting problems with the plant facility components and deficient hot-mix properties / acase@tulane.edu

acase@tulane.edu

acase@tulane.edu

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1985. / Bibliography: leaves 94-95. / by John Michael Spinelli. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1985. / Bibliography: leaves 97-102. / by Seth Robert Sanders. / M.S.

A physical model was used to study effects of gravity on areal recovery of a dense nonaqueous phase liquid (DNAPL) contaminant by alcohol pre-flooding and co-solvent flooding in dipping aquifers. Experimental results demonstrate a decrease in PCE recovery with increasing dip angle attributed to DNAPL swelling and migration, flood front instabilities, and bypassing of the source zone. Results demonstrate that alcohol pre-flooding can improve DNAPL recovery in the absence of a dip angle (horizontal orientation), but has negative effects when a dip angle exists. Electrokinetic experiments were conducted to examine effects of DC voltage gradient, pH, surfactants, ionic strength, and porous media on DNAPL movement in an electrical field. DNAPL movement was proportional to the applied voltage gradient and attributed to electroosmosis and electrophoresis. DNAPL droplets moved toward the cathodes under neutral and low pH conditions, and movement reversals were observed in high pH and ionic solutions / acase@tulane.edu

Sweet almond beta-glucosidase is a retaining, family 1, glycosidase that catalyzes the efficient hydrolysis of a broad range of substrates. The catalytic activity of the enzyme relies on two glutamic acid residues in the active site, one protonated and the other deprotonated. The hydrolysis of p-nitrophenyl beta-D-glucoside was found to rely on two groups with pKas of 4.00 and 7.10 with a (kcat/K M)lim value of 30,902 M-1 sec-1 , in agreement with the active site containing two carboxylic acid residues Hydrolysis and binding studies for a number of glucosides were carried out over a wide temperature range to determine thermodynamic parameters for the catalyzed reactions. These studies were used to determine what effects the enthalpy and entropy of activation have on increasing the rate of the reaction during catalysis. Results indicate that the significant rate improvement is due primarily to a more favorable enthalpy of activation for the catalyzed reaction resulting in rate enhancements between 1012-10 14 times faster than the spontaneous reactions at 25°C. The relative order of the first-order rate constants roughly follows the order predicted based on a Bronsted coefficient of -1, calculated under the assumption that the generally accepted mechanism is the correct mechanism for the substrates studied / acase@tulane.edu

Inherent characteristics (autogenic behavior) of sedimentary systems are often thought to generate small-scale noise in the stratigraphic records and usually ignored in the stratigraphic interpretation. However, autogenic dynamics can also occur over large temporal and spatial scales and produce sedimentary records that mimic stratigraphic signals presumed to result from changes in external boundary conditions (allogenic forcings) such as tectonics, climate, eustatic change or a combination. As the autogenic fluctuations could impose first-order controls on stratigraphic architecture, it is necessary to search for quantitative methods in order to constrain river intrinsic behaviors and decode them from the complex stratigraphic responses by the scales over which autogenic stratigraphic patterns are most prevalent. The statistical metric we developed based on numerical modeling and physical experiments offers a good prediction on the autogenic time scales and results in a compensation index which can be used as an indicator for fluviodeltaic stratigraphic patterns. The magnitude of autogenic forcings presented in the fluvial successions is associated with the strength of channel-belt clustering and can be quantitatively classified by the compensation index. We utilize this index in conjunction with a serial of 2-D object-based stratigraphic stacking models, high-resolution experimental and field data to (1) quantify how the magnitude of autogenic processes varies with scales (2) understand how autogenic behaviors interact with river discharge and how this allogenic condition affects the stacking patterns of channel bodies (3) explore the mechanism by which surface topography and river kinetics influence the degree of stratigraphic organization in a net-aggradation system / acase@tulane.edu