This poster is presented at the 2012 American Library Association Annual Conference in the Anaheim Convention Center. The hub on campus,... Show moreThis poster is presented at the 2012 American Library Association Annual Conference in the Anaheim Convention Center. The hub on campus, academic libraries play a significant role in promoting diversity and academic success. Library resources and services have a great impact on university’s recruitment, retention and graduation. This poster session discusses some innovative practices in outreach, effective support in student learning, diverse models in services, and successful approaches in connecting with the campus community. Show less
This poster, created by undergraduate students at the Illinois Institute of Technology (IIT), details Karl Menger's 1926-discovered fractal... Show moreThis poster, created by undergraduate students at the Illinois Institute of Technology (IIT), details Karl Menger's 1926-discovered fractal curve currently known as the Menger sponge. Menger is a former IIT faculty member. Show less
Superconducting RF (SRF) cavities made of Nb are an enabling device for future linear accelerators. Recently it has been demonstrated that hot... Show moreSuperconducting RF (SRF) cavities made of Nb are an enabling device for future linear accelerators. Recently it has been demonstrated that hot spots in SRF cavities, which diminish performance, are correlated with a high density of defects (etch pits) especially near grain boundaries. For a pit to cause local heating, it is likely that near-surface impurities, e.g. hydrides or oxides are leading to suppressed superconductivity. New probes are needed to measure such complexes. Here we present Raman spectroscopy. Raman is a fast, nonperturbative method that can measure the vibrational modes of Nb-O and Nb-H complexes by inelastic light scattering. These can then be compared to molecular dynamics simulations to identify oxide and hydride phases. The probing depth of Raman is estimated from the skin depth of the 785 nm laser in the bulk Nb ~ 10-20 nm. This is a reasonable fraction of the superconducting penetration depth ~ 45 nm. Simulating manufacturing processes of SRF cavities may shed light on the origins and composition of hot spots, and their relationship with defects in the material. Defects such as pits, whose origins are yet unknown, are found in the hot spots of completed cavities. Raman spectroscopy is used here to identify changes in the surface chemistry after manipulations such as creating artificial pits, exposing the material to chemical etching, or cold-working the material. BCP exposure and cold-working are common to the SRF manufacturing process. Show less
An RF measurement system with high time resolution is implemented to determine the statistical characteristics of various channels in the Land... Show moreAn RF measurement system with high time resolution is implemented to determine the statistical characteristics of various channels in the Land Mobile Radio bands. The applicability of simple statistical models to the observed data is investigated, as well as their validity over short and long periods of time. The results show that the statistics of the idle and holding times of communication on these channels vary significantly over time and demonstrate daily periodicity, requiring non-stationary models to accurately represent them. Over short durations of time however, conventional distributions such as the exponential and lognormal may adequately characterize the properties of these quantities, allowing convenient and compact representations of the data. Results based on empirical data are presented to quantify the probability of stationarity for voice traffic within a time span of given length. The findings are useful for network planning or streamlining, network simulation and modeling, and investigation of dynamic spectrum access. Sponsorship: National Science Foundation, Federal Communications Commission, Motorola, Cleversafe, Roberson & Associates LLC Show less
