Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 5 of 5

Full-Text Articles in Physical Sciences and Mathematics

Effect Of Sudden Stratospheric Warmingon Lunar Tidal Modulation Of The Equatorial Electrojet, J. Park, H. Luhr, M. Kunze, Bela G. Fejer, K. W. Min Mar 2012

Effect Of Sudden Stratospheric Warmingon Lunar Tidal Modulation Of The Equatorial Electrojet, J. Park, H. Luhr, M. Kunze, Bela G. Fejer, K. W. Min

Bela G. Fejer

[1] Using the equatorial electrojet (EEJ) peak current intensity as deduced from CHAMP magnetic observations from the years 2001 through 2009, we investigated the relationship between sudden stratospheric warming (SSW) and lunitidal signatures in the tropical ionosphere. There is a practically one-to-one correspondence between midwinter SSW periods and the strongest 13 day modulation of the EEJ strength as observed by CHAMP. That is, all the midwinter SSW periods from December 2001 to August 2009 were accompanied by an enhanced 13 day modulation of the EEJ strength. No other geophysical phenomenon brought about as strong a 13 day modulation as those …


Investigating Mountain Waves In Mtm Image Data At Cerro Pachon, Chile, Neal R. Criddle, M. J. Taylor, P.-D. Pautet, Y. Zhao, G. Swenson, A. Liu Jan 2012

Investigating Mountain Waves In Mtm Image Data At Cerro Pachon, Chile, Neal R. Criddle, M. J. Taylor, P.-D. Pautet, Y. Zhao, G. Swenson, A. Liu

Neal R Criddle

Gravity waves are important drivers of chemical species mixing, energy and momentum transfer into the MLT (~80 - 100 km) region. As part of a collaborative program involving instruments from several institutions Utah State University has operated a Mesospheric Temperature Mapper (MTM) at the new Andes Lidar Observatory (ALO) on Cerro Pachon (30.2°S, 70.7°W) Since August 2009. A primary goal of this program is to quantify the impact of mountain waves on the MLT region. The Andes region is an excellent natural laboratory for investigating gravity wave influences on the MLT region, especially the study of mountain waves, created by …


The Density Factor In The Synthesis Of Carbon Nanotube Forest By Injection Chemical Vapor Deposition, R. W. Call, C. G. Read, C. Mart, T. -C. Shen Jan 2012

The Density Factor In The Synthesis Of Carbon Nanotube Forest By Injection Chemical Vapor Deposition, R. W. Call, C. G. Read, C. Mart, T. -C. Shen

T. -C. Shen

Beneath the seeming straight-forwardness of growing carbon nanotube(CNT) forests by the injection chemical vapor deposition(CVD) method, control of the forest morphology on various substrates is yet to be achieved. Using ferrocene dissolved in xylene as the precursor, we demonstrate that the concentration of ferrocene and the injection rate of the precursor dictate the CNT density of these forests. However, CNT density will also be affected by the substrates and the growth temperature which determine the diffusion of the catalyst adatoms. The CNT growth rate is controlled by the temperature and chemical composition of the gases in the CVD reactor. We …


Windowed Pq-Grams For Approximate Joins Of Data-Centric Xml, Nikolaus Augsten, Michael H. Böhlen, Curtis Dyreson, Johann Gamper Jan 2012

Windowed Pq-Grams For Approximate Joins Of Data-Centric Xml, Nikolaus Augsten, Michael H. Böhlen, Curtis Dyreson, Johann Gamper

Curtis Dyreson

In data integration applications, a join matches elements that are common to two data sources. Since elements are represented slightly different in each source, an approximate join must be used to do the matching. For XML data, most existing approximate join strategies are based on some ordered tree matching technique, such as the tree edit distance. In data-centric XML, however, the sibling order is irrelevant, and two elements should match even if their subelement order varies. Thus, approximate joins for data-centric XML must leverage unordered tree matching techniques. This is computationally hard since the algorithms cannot rely on a predefined …


Adding Temporal Constraints To Xml Schema, Faiz Currim, Sabah Currim, Curtis Dyreson, Richard T. Snodgrass, Steven W. Thomas, Rui Zhang Jan 2012

Adding Temporal Constraints To Xml Schema, Faiz Currim, Sabah Currim, Curtis Dyreson, Richard T. Snodgrass, Steven W. Thomas, Rui Zhang

Curtis Dyreson

If past versions of XML documents are retained, what of the various integrity constraints defined in XML Schema on those documents? This paper describes how to interpret such constraints as sequenced constraints, applicable at each point in time. We also consider how to add new variants that apply across time, so-called non-sequenced constraints. Our approach supports temporal documents that vary over both valid and transaction time, whose schema can vary over transaction time. We do this by replacing the schema with a (possibly time-varying) temporal schema and replacing the document with a temporal document, both of which are upward compatible …