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Post-Optimization of Permutation Coverings

Description
Covering subsequences with sets of permutations arises in many applications, including event-sequence testing. Given a set of subsequences to cover, one is often interested in knowing the fewest number of permutations required to cover each subsequence, and in finding an explicit construction of such a set of permutations that has…

Covering subsequences with sets of permutations arises in many applications, including event-sequence testing. Given a set of subsequences to cover, one is often interested in knowing the fewest number of permutations required to cover each subsequence, and in finding an explicit construction of such a set of permutations that has size close to or equal to the minimum possible. The construction of such permutation coverings has proven to be computationally difficult. While many examples for permutations of small length have been found, and strong asymptotic behavior is known, there are few explicit constructions for permutations of intermediate lengths. Most of these are generated from scratch using greedy algorithms. We explore a different approach here. Starting with a set of permutations with the desired coverage properties, we compute local changes to individual permutations that retain the total coverage of the set. By choosing these local changes so as to make one permutation less "essential" in maintaining the coverage of the set, our method attempts to make a permutation completely non-essential, so it can be removed without sacrificing total coverage. We develop a post-optimization method to do this and present results on sequence covering arrays and other types of permutation covering problems demonstrating that it is surprisingly effective.
ContributorsMurray, Patrick Charles (Author) / Colbourn, Charles (Thesis director) / Czygrinow, Andrzej (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Department of Physics (Contributor)
Created2014-12
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Measuring Beam Energy and Energy Jitter on the Compact X-Ray Light Source

Description

For this thesis, the energy of the CXLS electron beam was measured and the beam’s energy jitter was calculated. It is essential to characterize the beam’s en- ergy and energy jitter in order to ensure that the powerful x-rays produced by CXLS will be of a consistent and desirable energy.…

For this thesis, the energy of the CXLS electron beam was measured and the beam’s energy jitter was calculated. It is essential to characterize the beam’s en- ergy and energy jitter in order to ensure that the powerful x-rays produced by CXLS will be of a consistent and desirable energy. The energy of the electrons within the electron beam can be calculated through utilizing basic physics prin- ciples and the geometry of the beamline. The energy of the beam for the data collected was found to be 3.426 MeV at POP module 1 and 12.3 MeV at POP module 9. The energy jitter of the beam was determined for four different angle settings of the VPSPD for linac 1 and found to be lowest when the linac 1 VPSPD was set to an angle of 97°. The energy jitter of the beam was 1.50e-03 MeV when the VPSPD for linac 1 was set to 97°.
ContributorsLarsen, Rachel (Author) / Graves, William (Thesis director) / Teitelbaum, Samuel (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / Department of Physics (Contributor)
Created2022-05
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Jitter Measurement of Compact X-ray Light Source Radio Frequency System

Description
The Compact X-ray Light Source is an x-ray source at ASU that allows scientists to study the structures and dynamics of matter on an atomic scale. The radio frequency system that provides the power to accelerate electrons in the Compact X-ray Light Source must operate with a high degree of…

The Compact X-ray Light Source is an x-ray source at ASU that allows scientists to study the structures and dynamics of matter on an atomic scale. The radio frequency system that provides the power to accelerate electrons in the Compact X-ray Light Source must operate with a high degree of precision. This thesis measures the precision with which that system performs.
ContributorsBabic, Gregory (Author) / Graves, William (Thesis director) / Kitchen, Jennifer (Committee member) / Holl, Mark (Committee member) / Barrett, The Honors College (Contributor) / Electrical Engineering Program (Contributor) / Department of Physics (Contributor)
Created2022-05