4,420 research outputs found
Data analysis of P sub T/P sub S noseboom probe testing on F100 engine P680072 at NASA Lewis Research Center
Results from the altitude testing of a P sub T/P sub S noseboom probe on the F100 engine are discused. The results are consistent with sea level test results. The F100 engine altitude test verified automatic downmatch with the engine pressure ratio control, and backup control inlet case static pressure demonstrated sufficient accuracy for backup control fuel flow scheduling. The production P6 probe measured Station 6 pressures accurately for both undistorted and distorted inlet airflows
Adaptive system and method for signal generation Patent
Adaptive signal generating system and logic circuits for satellite television system
LANDSAT-4 TM image data quality analysis for energy-related applications
LANDSAT-4 Thematic Mapper (TM) data performance and utility characteristics from an energy research and technology perspective is evaluated. The program focuses on evaluating applicational implications of using such data, in combination with other digital data, for current and future energy research and technology activities. Prime interest is in using TM data for siting, developing and operating federal energy facilities. Secondary interests involve the use of such data for resource exploration, environmental monitoring and basic scientific initiatives such as in support of the Continental Scientific Drilling Program
Dynamics of clade diversification on the morphological hypercube
Understanding the relationship between taxonomic and morphological changes is
important in identifying the reasons for accelerated morphological
diversification early in the history of animal phyla. Here, a simple general
model describing the joint dynamics of taxonomic diversity and morphological
disparity is presented and applied to the data on the diversification of
blastozoans. I show that the observed patterns of deceleration in clade
diversification can be explicable in terms of the geometric structure of the
morphospace and the effects of extinction and speciation on morphological
disparity without invoking major declines in the size of morphological
transitions or taxonomic turnover rates. The model allows testing of hypotheses
about patterns of diversification and estimation of rates of morphological
evolution. In the case of blastozoans, I find no evidence that major changes in
evolutionary rates and mechanisms are responsible for the deceleration of
morphological diversification seen during the period of this clade's expansion.
At the same time, there is evidence for a moderate decline in overall rates of
morphological diversification concordant with a major change (from positive to
negative values) in the clade's growth rate.Comment: 8 pages, Latex, 2 postscript figures, submitted to Proc.R.Soc.Lond.
LANDSAT TM image data quality analysis for energy-related applications
This project represents a no-cost agreement between National Aeronautic Space Administration Goddard Space Flight Center (NASA GSFC) and the Pacific Northwest Laboratory (PNL). PNL is a Department of Energy (DOE) national laboratory operted by Battelle Memorial Institute at its Pacific Northwest Laboratories in Richland, Washington. The objective of this investigation is to evaluate LANDSAT's thematic mapper (TM) data quality and utility characteristics from an energy research and technological perspective. Of main interest is the extent to which repetitive TM data might support DOE efforts relating to siting, developing, and monitoring energy-related facilities, and to basic geoscientific research. The investigation utilizes existing staff and facility capabilities, and ongoing programmatic activities at PNL and other DOE national laboratories to cooperatively assess the potential usefulness of the improved experimental TM data. The investigation involves: (1) both LANDSAT 4 and 5 TM data, (2) qualitative and quantitative use consideration, and 3) NASA P (corrected) and A (uncorrected) CCT analysis for a variety of sites of DOE interest. Initial results were presented at the LANDSAT Investigator's Workshops and at specialized LANDSAT TM sessions at various conferences
National flood modelling for insurance purposes: using IFSAR for flood risk estimation in Europe
International audienceFlood risk poses a major problem for insurers and governments who ultimately pay the financial costs of losses resulting from flood events. Insurers therefore face the problem of how to assess their exposure to floods and how best to price the flood element of their insurance products. This paper looks at the insurance implications of recent flood events in Europe and the issues surrounding insurance of potential future events. In particular, the paper will focus on the flood risk information needs of insurers and how these can be met. The data requirements of national and regional flood models are addressed in the context of the accuracy of available data on property location. Terrain information is generally the weakest component of sophisticated flood models. Therefore, various sources of digital terrain models (DTM) are examined and discussed with consideration of the vertical and horizontal accuracy, the speed of acquisition, the costs and the comprehensiveness of the data. The NEXTMap DTM series from Intermap Technologies Inc. is proposed as a suitable DTM for flood risk identification and mapping, following its use in the UK. Its acquisition, processing and application is described and future plans discussed. Examples are included of the application of flood information to insurance property information and the potential benefits and advantages of using suitable hazard modelling data sources are detailed
Dysflective cones: Visual function and cone reflectivity in long-term follow-up of acute bilateral foveolitis.
PURPOSE:Confocal adaptive optics scanning laser ophthalmoscope (AOSLO) images provide a sensitive measure of cone structure. However, the relationship between structural findings of diminished cone reflectivity and visual function is unclear. We used fundus-referenced testing to evaluate visual function in regions of apparent cone loss identified using confocal AOSLO images. METHODS:A patient diagnosed with acute bilateral foveolitis had spectral-domain optical coherence tomography (SD-OCT) (Spectralis HRA + OCT system [Heidelberg Engineering, Vista, CA, USA]) images indicating focal loss of the inner segment-outer segment junction band with an intact, but hyper-reflective, external limiting membrane. Five years after symptom onset, visual acuity had improved from 20/80 to 20/25, but the retinal appearance remained unchanged compared to 3 months after symptoms began. We performed structural assessments using SD-OCT, directional OCT (non-standard use of a prototype on loan from Carl Zeiss Meditec) and AOSLO (custom-built system). We also administered fundus-referenced functional tests in the region of apparent cone loss, including analysis of preferred retinal locus (PRL), AOSLO acuity, and microperimetry with tracking SLO (TSLO) (prototype system). To determine AOSLO-corrected visual acuity, the scanning laser was modulated with a tumbling E consistent with 20/30 visual acuity. Visual sensitivity was assessed in and around the lesion using TSLO microperimetry. Complete eye examination, including standard measures of best-corrected visual acuity, visual field tests, color fundus photos, and fundus auto-fluorescence were also performed. RESULTS:Despite a lack of visible cone profiles in the foveal lesion, fundus-referenced vision testing demonstrated visual function within the lesion consistent with cone function. The PRL was within the lesion of apparent cone loss at the fovea. AOSLO visual acuity tests were abnormal, but measurable: for trials in which the stimulus remained completely within the lesion, the subject got 48% correct, compared to 78% correct when the stimulus was outside the lesion. TSLO microperimetry revealed reduced, but detectible, sensitivity thresholds within the lesion. CONCLUSIONS AND IMPORTANCE:Fundus-referenced visual testing proved useful to identify functional cones despite apparent photoreceptor loss identified using AOSLO and SD-OCT. While AOSLO and SD-OCT appear to be sensitive for the detection of abnormal or absent photoreceptors, changes in photoreceptors that are identified with these imaging tools do not correlate completely with visual function in every patient. Fundus-referenced vision testing is a useful tool to indicate the presence of cones that may be amenable to recovery or response to experimental therapies despite not being visible on confocal AOSLO or SD-OCT images
Transport through an impurity tunnel coupled to a Si/SiGe quantum dot
Achieving controllable coupling of dopants in silicon is crucial for
operating donor-based qubit devices, but it is difficult because of the small
size of donor-bound electron wavefunctions. Here we report the characterization
of a quantum dot coupled to a localized electronic state, and we present
evidence of controllable coupling between the quantum dot and the localized
state. A set of measurements of transport through this device enable the
determination of the most likely location of the localized state, consistent
with an electronically active impurity in the quantum well near the edge of the
quantum dot. The experiments we report are consistent with a gate-voltage
controllable tunnel coupling, which is an important building block for hybrid
donor and gate-defined quantum dot devices.Comment: 5 pages, 3 figure
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