Survey on excess classrooms for Black Studies use

Memo that addresses a study of both the excess of classrooms and the lack of time and space allotted to black studies. The research shows that class and seminar rooms were occupied 35% of the time and the lecture halls only 26% of the time. The study was conducted by the following: Lawrence Beinert, Dave Covintree, Rick Miller, Brad Wernle, David Croushore, Mike Murray, Bill Berkshire, Ashley Butil, Robert Cullen, Kenneth Stoddard. It is date stamped Mar 17 1970

Foam formation in a PMMA-methanol system

The overall objective of this PhD thesis is to contribute to a greater understanding of the mechanisms involved in the generation of low density and low cell size polymeric foams. Specifically, this means to understand what parameters contribute to an increase in nucleation density and a decrease in cell size. Polymeric foams with low cell size and density serve a lot of different applications such as lightweight insulation, filtration, catalysis as well as tissue engineering. A decrease in density and cell size below 70 nm leads to an increase in mechanical properties and a decrease in thermal conductivity compared to conventional foams with cell sizes in the micrometer range. Below a cell size of 40 nm, optical transparency can be achieved. Such nanocellular foams are produced using high-pressure infiltration of CO2 in an autoclave followed by rapid depressurisation. This makes it difficult to observe the process experimentally and determine mechanisms and parameters influencing nucleation and growth. In order to obtain an insight into nucleation and growth mechanisms that are potentially relevant for nanofoam formation, a novel solid-state foaming process employing PMMA and methanol was developed. The process is partly analogous to the CO2-based nanofoam development process, but experimentally more accessible. This foam and its development were characterized and important mechanisms in the process for nucleation and void development were identified. The most important finding was that methanol-desorption-induced stresses develop and gradually expand post-critical nuclei into a foamable state. This desorption-induced stress-development and consequent nuclei expansion was identified as a necessary parameter to achieve foam formation within the PMMA and methanol system. It was shown that externally applied stresses also contribute to nuclei expansion towards a foamable state. Furthermore, the expansional effect of externally applied stresses superimposes with the expansional effect on nuclei development of desorption-induced stresses. Altogether, desorption-induced stress development could be identified as a so far unrecognized mechanism that influences foam development. Furthermore, it was observed that an increase in sample (methanol-charged PMMA in unfoamed state) temperature following a freeze is also a source of stress resulting from density differences. Since the nano-foam production process comprises desorption as well as a temperature increase following a freeze, the hereby resulting stresses are potentially relevant in the nano-foam production process as well. The implications of this work for the production of nanofoams is therefore the identification of production-accompanied stress development as a foam properties influencing magnitude

Non-contacting Seals in Screw Compressors

Screw compressors are currently the most frequently used compressor type in the field of industrial compressed air production. Because end products are only allowed to come into contact with absolutely clean compressed air in many fields of industry, there is a considerable demand on the market for the production of compressed air that is entirely oil-free. The high acquisition costs of dry-running compressor systems and the disadvantages in energy terms compared to oil-injected designs need to be offset by a long useful life and guaranteed reliability. The compressor\u27s integrated sealing system makes an important contribution here. High peripheral speeds and pressure differences largely rule out the use of simple, contacting seal systems and drive forward continuous optimization in relation to function and production costs. Based on the calculation of compressible outflows at annular gaps and experimental studies, the sealing performance of various gas choke seals for use in screw compressors will be analyzed and evaluated. Here, the main criteria of pressure reduction and barrier effectiveness, as well as the size and geometric complexity of the seal will be considered. This paper shows that the flows simulated with the help of a chamber model, using pressure-dependent flow coefficients and overflow factors, allow a good comparison in qualitative terms with the real, measured permeability curve for designing sealing systems for dry-running screw compressors