6,367 research outputs found
One Repeat Point Gives a Closed, Unbounded Ultrafilter on {\omega_1}
It is shown that the consistency strength of ZF + DC + "the closed unbounded
ultrafilter on omega_1 is an ultrafilter" is exactly ZFC + one measurable
cardinal.Comment: I apologize for the fact that this is not ready for publication. I've
gone back to revise it several times, and each time got distracted by
something new. I've decided that it is better to at least make it available
in its current for
Using a temperature-controlled quartz crystal microbalance in a space equipment cleanroom to monitor molecular contamination
There is a need for continuous monitoring for molecular contamination in clean rooms where spaceflight equipment is assembled, integrated, and tested to insure that contamination budgets are met. The TQCM (temperature-controlled quartz crystal microbalance) can be used to provide both a real time warning and a cumulative measurement of molecular contamination. It has advantages over the other measurement methods such as witness mirrors, NVR (non-volatile residue) plates, and gas analyzers. A comparison of the TQCM sensitivity and ease of operations is made with the other methods. The surface acoustic wave microbalance (SAW), a newly developed instrument similar to TQCM, is considered in the comparison. An example is provided of TQCM use at Goddard Space Flight Center when the Wide Field Planetary Camera 2(WFPC-2) and the Corrective Optics Space Telescope Axial Replacement (COSTAR) were undergoing integrated testing prior to their installation in the Hubble Space Telescope on its first servicing mission. Areas for further investigation are presented
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