25,387 research outputs found
Measurements of aerosol properties needed to infer backscatter characteristics in support of the NASA Doppler Lidar program
During the first year two areas of work were emphasized, analysis of aerosol data to provide improved estimates of backscatter over the Pacific ocean and development of a global model for backscatter at different wavelengths and preparation and planning for the aircraft flights of the GLOVE program. Significant progress was made in each of these areas. The analytical work is a continuation of the GAMETAG analysis, and was directed toward the development of a backscatter model for the Pacific Oceanic free troposphere. This has included a further evaluation of relationships between the optical effects at different wavelengths, a comparison of modeled optical effects at differing temporal resolutions, and an investigation of the effects of sampling on the modeled results. An initial investigation of the predictability of 9 to 10 micrometers Beta values from other data sets as well as some preliminary comparisons of the modeling results with experimental data. The comparison of the optical effects was extended to make the comparisons for different sets of time bases between 1 and 20 minutes
Improved simulation of aerosol, cloud, and density measurements by shuttle lidar
Data retrievals are simulated for a Nd:YAG lidar suitable for early flight on the space shuttle. Maximum assumed vertical and horizontal resolutions are 0.1 and 100 km, respectively, in the boundary layer, increasing to 2 and 2000 km in the mesosphere. Aerosol and cloud retrievals are simulated using 1.06 and 0.53 microns wavelengths independently. Error sources include signal measurement, conventional density information, atmospheric transmission, and lidar calibration. By day, tenuous clouds and Saharan and boundary layer aerosols are retrieved at both wavelengths. By night, these constituents are retrieved, plus upper tropospheric, stratospheric, and mesospheric aerosols and noctilucent clouds. Density, temperature, and improved aerosol and cloud retrievals are simulated by combining signals at 0.35, 1.06, and 0.53 microns. Particlate contamination limits the technique to the cloud free upper troposphere and above. Error bars automatically show effect of this contamination, as well as errors in absolute density nonmalization, reference temperature or pressure, and the sources listed above. For nonvolcanic conditions, relative density profiles have rms errors of 0.54 to 2% in the upper troposphere and stratosphere. Temperature profiles have rms errors of 1.2 to 2.5 K and can define the tropopause to 0.5 km and higher wave structures to 1 or 2 km
High Speed Photometry of SDSS J013701.06-091234.9
We present high speed photometry of the Sloan Digital Sky Survey cataclysmic
variable SDSS J013701.06-091234.9 in quiescence and during its 2003 December
superoutburst. The orbital modulation at 79.71\pm0.01 min is double humped; the
superhump period is 81.702\pm0.007 min. Towards the end of the outburst late
superhumps with a period of 81.29\pm0.01 min were observed. We argue that this
is a system of very low mass transfer rate, and that it probably has a long
outburst interval.Comment: 5 pages, 8 figures. Accepted for publication in MNRA
A Miniaturized Cassegrainian Concentrator Solar Array for High Power Space Applications.
A miniaturized Cassegrainian concentrator (MCC) solar array system concept is under preliminary development for the space station or for other large spacecraft/space platform mission applications that may require power at the 100 kilowatt level or higher. The concept has many of the physical attributes of planar rigid-panel solar arrays and does not require unusual deployment or thermal management methods or auxiliaries. Furthermore, it promises both lower initial cost and lower life cycle cost than state-of-the-art lightweight planar flexible blanket solar arrays. The paper briefly describes the MCC concept and presents the results of a life cycle cost comparison analysis that shows that solar array area (rather than weight) is the key cost parameter at the lowest candidate space station basing altitudes. With smaller area than its planar array counterpart, the MCC array offers a 20 to 30 percent reduction in life cycle cost
Development of global model for atmospheric backscatter at CO2 wavelengths
The improvement of an understanding of the variation of the aerosol backscattering at 10.6 micron within the free troposphere and the development model to describe this was undertaken. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets are obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained, which describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season. Most data are available and greatest consistency is found inside the Northern Hemisphere
Development of a global model for atmospheric backscatter at CO2 wavelengths
The variation of the aerosol backscattering at 10.6 micrometers within the free troposphere was investigated and a model to describe this variation was developed. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets used were obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series, and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained that describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season
Simultaneous bistability of qubit and resonator in circuit quantum electrodynamics
We explore the joint activated dynamics exhibited by two quantum degrees of
freedom: a cavity mode oscillator which is strongly coupled to a
superconducting qubit in the strongly coherently driven dispersive regime.
Dynamical simulations and complementary measurements show a range of parameters
where both the cavity and the qubit exhibit sudden simultaneous switching
between two metastable states. This manifests in ensemble averaged amplitudes
of both the cavity and qubit exhibiting a partial coherent cancellation.
Transmission measurements of driven microwave cavities coupled to transmon
qubits show detailed features which agree with the theory in the regime of
simultaneous switching
Search for the electric dipole moment of the electron with thorium monoxide
The electric dipole moment of the electron (eEDM) is a signature of
CP-violating physics beyond the Standard Model. We describe an ongoing
experiment to measure or set improved limits to the eEDM, using a cold beam of
thorium monoxide (ThO) molecules. The metastable state in ThO
has important advantages for such an experiment. We argue that the statistical
uncertainty of an eEDM measurement could be improved by as much as 3 orders of
magnitude compared to the current experimental limit, in a first-generation
apparatus using a cold ThO beam. We describe our measurements of the state
lifetime and the production of ThO molecules in a beam, which provide crucial
data for the eEDM sensitivity estimate. ThO also has ideal properties for the
rejection of a number of known systematic errors; these properties and their
implications are described.Comment: v2: Equation (11) correcte
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