Parametric study of space power systems. Volume 1 - Summary Final report

Summary of methodology and results of study of space power system

Fractures and lineaments of Sicily Island: Preliminary results on analog optical techniques

There are no author-identified significant results in this report

Plantinga-Vegter algorithm takes average polynomial time

We exhibit a condition-based analysis of the adaptive subdivision algorithm due to Plantinga and Vegter. The first complexity analysis of the PV Algorithm is due to Burr, Gao and Tsigaridas who proved a $O\big(2^{\tau d^{4}\log d}\big)$ worst-case cost bound for degree $d$ plane curves with maximum coefficient bit-size $\tau$. This exponential bound, it was observed, is in stark contrast with the good performance of the algorithm in practice. More in line with this performance, we show that, with respect to a broad family of measures, the expected time complexity of the PV Algorithm is bounded by $O(d^7)$ for real, degree $d$, plane curves. We also exhibit a smoothed analysis of the PV Algorithm that yields similar complexity estimates. To obtain these results we combine robust probabilistic techniques coming from geometric functional analysis with condition numbers and the continuous amortization paradigm introduced by Burr, Krahmer and Yap. We hope this will motivate a fruitful exchange of ideas between the different approaches to numerical computation.Comment: 8 pages, correction of typo

Super-quadratic behavior of luminescence decay excited by energy-transfer upconversion

For several decades, energy-transfer upconversion (ETU) in rare-earth-ion doped systems [1,2] has attracted much attention, firstly, because of the fundamental interest in the physical nature of this process and, secondly, because of very practical considerations, namely the demonstration of near-infrared pumped visible light sources and, in reverse, the detrimental influence of ETU on the efficiency of infrared emitting systems.\ud We investigate fundamentally the behavior of infrared luminescence emitted directly from a metastable level and visible luminescence emitted after ETU from this level to higher-lying levels. Although these two luminescences are connected by the same metastable level and influenced by the same ETU process, the infrared luminescence probes all ions, while the visible luminescence probes only the class of ions susceptible to ETU [3]. A simple analytical model [4] predicts that such luminescence decay curves exhibit a super-quadratic dependence of upconversion on direct luminescence decay.\ud The Nd3+ ion can serve as a model system for such investigations. It exhibits strong ETU from the metastable 4F3/2 level. When doped into oxide matrices, the 4F3/2 level is the only metastable level. The Nd3+ energy levels excited by ETU decay by fast multiphonon relaxation and, hence, the weak visible fluorescence emitted from these levels represents a quasi instantaneous reaction on the dynamics of the 4F3/2 level. Experimental results obtained after pulsed laser excitation of Nd3+-doped oxide host materials show indeed a super-quadratic behavior of upconversion versus direct luminescence decay, in accordance with the model predictions [4].\ud \ud [1] F. Auzel, Proc. IEEE 1973, 6, 758\ud [2] J.C. Wright, Top. Appl. Phys. 1976, 15, 239\ud [3] M. Pollnau, D.R. Gamelin, S.R. Lüthi, H.U. Güdel, M.P. Hehlen, Phys. Rev. B 2000, 61, 3337\ud [4] M. Pollnau, J. Alloys Compd. 2002, 341, 5

Results of Skylab investigation over Italy

The author has identified the following significant results. Multispectral high resolution photography of S190A was successfully applied to the detection of paleoriverbeds in flat lands. Results of SL-3 mission were compared to those of LANDSAT for two regional geological surveys (linear structures) on the islands of Sicily and Sardinia. On Sicily, the seasonal conditions were unfavorable for Skylab while LANDSAT played a major role in discovering long, unknown lineaments of great interest for the geodynamics of the area. On Sardinia, owing to the vegetation type and to the geomorphic conditions, the Skylab imagery was successfully employed to describe the network of linears, both regional and local. Results can be used to study the relationship between linears, actual fracturing and the occurrence of mineral deposits

Superquadratic behavior of upconversion luminescence transients in rare-earth-ion doped laser crystals

Inhomogeneous active-ion distributions in laser materials lead to strong deviations of upconversion versus direct luminescence transients from the quadratic law of energy-transfer upconversion. Measured luminescence decay curves in LaSc3(BO3)4:Nd3+ and GdVO4:Nd3+ confirm experimentally the predicted deviations. Differences in energy migration within the metastable level of Nd3+ are identified

An Avian-Centered Model for the Dispersal of Ixodes scapularis by Fall Songbird Migrants

Lyme disease caused by Borrelia burgdorferi infection is the most common vector-borne illness in the United States, and has become increasingly reported since it was first described clinically. The tick species Ixodes scapularis is responsible for disease transmission between endothermic hosts. Consequently, the spatial patterns of human infection are positively correlated with population densities of the tick. Field observations have shown that migrating songbirds often carry ticks during the fall as they travel southward. However, no research currently predicts or demonstrates the magnitude of tick dispersal by fall migrants. The goal of this research was to develop an individual-based model of avian migration and bird-tick interactions to investigate species-specific patterns of I. scapularis dispersal within the continental United States by southward migrating songbirds. The model used in this research predicts the dispersal of over a million ticks outside of the current range of the species to most areas predicted to be climatically suitable for the tick, both presently and in the future. Out of areas without an established tick population, Eastern Minnesota, Iowa, Virginia and North Carolina experienced the highest level of tick detachment events, suggesting that birds may play a significant role in the range expansion of I. scapularis into these regions. This model suggests that the dispersal of I. scapularis by avian species is a critical factor in determining human infection risk to Lyme disease and other tick-borne pathogens in the United States. In the future, this model can be used as a virtual laboratory to analyze how local climate change patterns may impact the dispersal and range expansion of I. scapularis through changes to the phenological synchrony of ticks and songbirds

Contribution of Skylab multispectral imagery to the remote sensing studies of Mount Etna volcano

There are no author-identified significant results in this report

Parametric Study of Space Power Systems. Volume 2 - Technical Report Final Report

Computer program for analysis of space power system