Space Station RT and E Utilization Study

Descriptive information on a set of 241 mission concepts was reviewed to establish preliminary Space Station outfitting needs for technology development missions. The missions studied covered the full range of in-space technology development activities envisioned for early Space Station operations and included both pressurized volume and attached payload requirements. Equipment needs were compared with outfitting plans for the life sciences and microgravity user communities, and a number of potential outfitting additions were identified. Outfitting implementation was addressed by selecting a strawman mission complement for each of seven technical themes, by organizing the missions into flight scenarios, and by assessing the associated outfitting buildup for planning impacts

Casimir interactions in graphene systems

The non-retarded Casimir interaction (van der Waals interaction) between two free standing graphene sheets as well as between a graphene sheet and a substrate is determined. An exact analytical expression is given for the dielectric function of graphene along the imaginary frequency axis within the random phase approximation for arbitrary frequency, wave vector, and doping.Comment: 4 pages, 4 figure

Closed-circuit television welding- electrode guidance system

Closed-circuit TV camera is mounted parallel to electrode and moves along with it. Camera is scanned along seam so seam is viewed parallel with scan lines on TV monitor. Two fiber optics illuminators are attached to guidance system; they illuminate seam for TV camera

Nonlinear electromagnetic response of graphene: Frequency multiplication and the self-consistent-field effects

Graphene is a recently discovered carbon based material with unique physical properties. This is a monolayer of graphite, and the two-dimensional electrons and holes in it are described by the effective Dirac equation with a vanishing effective mass. As a consequence, electromagnetic response of graphene is predicted to be strongly non-linear. We develop a quasi-classical kinetic theory of the non-linear electromagnetic response of graphene, taking into account the self-consistent-field effects. Response of the system to both harmonic and pulse excitation is considered. The frequency multiplication effect, resulting from the non-linearity of the electromagnetic response, is studied under realistic experimental conditions. The frequency up-conversion efficiency is analysed as a function of the applied electric field and parameters of the samples. Possible applications of graphene in terahertz electronics are discussed.Comment: 14 pages, 7 figures, invited paper written for a special issue of JPCM "Terahertz emitters

The ocean's saltiness and its overturning

Here we explore the relationship between the mean salinity urn:x-wiley:grl:media:grl55555:grl55555-math-0001 of the ocean and the strength of its Atlantic and Pacific Meridional Overturning Circulations (AMOC and PMOC). We compare simulations performed with a realistically configured coarse‐grained ocean model, spanning a range of mean salinities. We find that the AMOC strength increases approximately linearly with urn:x-wiley:grl:media:grl55555:grl55555-math-0002. In contrast, the PMOC strength declines approximately linearly with urn:x-wiley:grl:media:grl55555:grl55555-math-0003 until it reaches a small background value similar to the present‐day ocean. Well‐established scaling laws for the overturning circulation explain both of these dependencies on urn:x-wiley:grl:media:grl55555:grl55555-math-0004

Upper ocean manifestations of a reducing meridional overturning circulation

Most climate models predict a slowing down of the Atlantic Meridional Overturning Circulation during the 21st century. Using a 100year climate change integration of a high resolution coupled climate model, we show that a 5.3Sv reduction in the deep southward transport in the subtropical North Atlantic is balanced solely by a weakening of the northward surface western boundary current, and not by an increase in the southward transport integrated across the interior ocean away from the western boundary. This is consistent with Sverdrup balance holding to a good approximation outside of the western boundary region on decadal time scales, and may help to spatially constrain past and future change in the overturning circulation. The subtropical gyre weakens by 3.4Sv over the same period due to a weakened wind stress curl. These changes combine to give a net 8.7Sv reduction in upper western boundary transport. © 2012. American Geophysical Union. All Rights Reserved

Mechanical energy input to the world oceans due to atmospheric loading

Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Science in China Press for personal use, not for redistribution. The definitive version was published in Chinese Science Bulletin 51 (2006): 327-330, doi:10.1007/s11434-006-0327-x.Mechanical energy input to the oceans is one of the most important factors controlling the oceanic general circulation. The atmosphere transports mechanical energy to the oceans primarily through wind stress, plus changes of the sea level pressure (the so-called atmospheric loading). The rate of mechanical energy transfer into the ocean due to atmospheric loading is calculated, based on TOPEX/POSEIDON data over ten-year period (1993-2002). The rate of total energy input for the world oceans is estimated at 0.04TW (1TW=1012W), and most of this energy input is concentrated in the Southern Oceans and the Storm Tracks in the Northern Hemisphere. This energy input varied greatly with time, and the amplitude of the interannual variability over the past ten years is about 15%.WW and CCQ were supported by the National Nature Science Foundation of China through grant 40476010 and Research Fund for the Doctoral Program of Higher Education through grant 20030423011. RXH was supported by the National Aero-Space Administration through Contract No. 1229833 (NRA-00-OES-05)

The Oceanic Variability Spectrum and Transport Trends

Oceanic meridional transports evaluated over the width of the Pacific Ocean from altimetric observations become incoherent surprisingly rapidly with meridional separation. Even with 15 years of data, surface slopes show no significant coherence beyond 5◦ of latitude separation at any frequency. An analysis of the frequency/zonal-wavenumber spectral density shows a broad continuum of motions at all time and space scales, with a significant excess of energy along a “non-dispersive” line extending between the simple barotropic and first baroclinic mode Rossby waves. It is speculated that much of that excess energy lies with coupled barotropic and first mode Rossby waves. The statistical significance of apparent oceanic transport trends depends upon the existence of a reliable frequency/wavenumber spectrum and for which only a few observational elements now exist.Jet Propulsion Laboratory (U.S.).United States. National Aeronautics and Space Administration (Jason-1 program)National Oceanographic Partnership Program (U.S.

Obliquity pacing of the late Pleistocene glacial terminations

Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 434 (2005): 491-494, doi:10.1038/nature03401.The timing of glacial/interglacial cycles at intervals of about 100,000 yr (100 kyr) is commonly attributed to control by Earth orbital configuration variations. This “pacemaker” hypothesis has inspired many models, variously depending upon Earth obliquity, orbital eccentricity, and precessional fluctuations, with the latter usually emphasized. A contrasting hypothesis is that glacial cycles arise primarily because of random internal climate variability. Progress requires distinguishing between the more than 30 proposed models of the late Pleistocene glacial variations. Here we present a formal test of the pacemaker hypothesis, focusing on the rapid deglaciation events known as terminations. The null hypothesis that glacial terminations are independent of obliquity can be rejected at the 5% significance level. In contrast, for eccentricity and precession, the corresponding null-hypotheses cannot be rejected. The simplest inference, consistent with the observations, is that ice-sheets terminate every second (80 kyr) or third (120 kyr) obliquity cycle — at times of high obliquity — and similar to the original Milankovitch assumption. Hypotheses not accounting for the obliquity pacing are unlikely to be correct. Both stochastic and deterministic variants of a simple obliquity-paced model describe the observations.PH is supported by the NOAA Postdoctoral Program in Climate and Global Change and CW in part by the National Ocean Partnership Program (ECCO)

Strained graphene: tight-binding and density functional calculations

We determine the band structure of graphene under strain using density functional calculations. The ab-initio band strucure is then used to extract the best fit to the tight-binding hopping parameters used in a recent microscopic model of strained graphene. It is found that the hopping parameters may increase or decrease upon increasing strain, depending on the orientation of the applied stress. The fitted values are compared with an available parametrization for the dependence of the orbital overlap on the distance separating the two carbon atoms. It is also found that strain does not induce a gap in graphene, at least for deformations up to 10%