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Additions to the NASA Aeronautics and Space Database as of 08/20/2008
20080030332 NASA Goddard Space Flight Center, Greenbelt, MD, United States
A Simple Stochastic Model for Generating Broken Cloud Optical Depth and Top Height Fields
Prigarin, Sergei M.; Marshak, Alexander; December 09, 2007; In English; Original contains black and white illustrations
Contract(s)/Grant(s): DE-A105-90ER61069NSF 05-1000008-8024; RFBR-06-05-54484; NSh-4774.2006.1621-30-86; 622-42-57
Copyright; Avail.: CASI: A03, Hardcopy
A simple and fast algorithm for generating two correlated stochastic twodimensional (2D) cloud fields is described. The algorithm is illustrated with two broken cumulus cloud fields: cloud optical depth and cloud top height retrieved from Moderate Resolution Imaging Spectrometer (MODIS). Only two 2D fields are required as an input. The algorithm output is statistical realizations of these two fields with approximately the same correlation and joint distribution functions as the original ones. The major assumption of the algorithm is statistical isotropy of the fields. In contrast to fractals and the Fourier filtering methods frequently used for stochastic cloud modeling, the proposed method is based on spectral models of homogeneous random fields. For keeping the same probability density function as the (first) original field, the method of inverse distribution function is used. When the spatial distribution of the first field has been generated, a realization of the correlated second field is simulated using a conditional distribution matrix. This paper is served as a theoretical justification to the publicly available software that has been recently released by the authors and can be freely downloaded from http://i3rc.gsfc.nasa.gov/Public codes clouds.htm. Though 2D rather than full 3D, stochastic realizations of two correlated cloud fields that mimic statistics of given fields have proved to be very useful to study 3D radiative transfer features of broken cumulus clouds for better understanding of shortwave radiation and interpretation of the remote sensing retrievals.
Author
ALGORITHMS; CLOUD HEIGHT INDICATORS; CUMULUS CLOUDS; DISTRIBUTION FUNCTIONS; REMOTE SENSING; MODIS (RADIOMETRY); IMAGING SPECTROMETERS; MATHEMATICAL MODELS; CORRELATION
20080030334 NASA Goddard Space Flight Center, Greenbelt, MD, United States
X-Ray Dust Scattering At Small Angles: The Complete Halo Around GX13+1
Smith, Randall K.; [2007]; In English; Original contains black and white illustrations
Contract(s)/Grant(s): GO-6144X
No Copyright; Avail.: CASI: A02, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030334
The exquisite angular resolution available with Chandra should allow precision measurements of faint diffuse emission surrounding bright sources, such as the X-ray scattering halos created by interstellar dust. However, the ACIS CCDs suffer from pileup when observing bright sources, and this creates difficulties when trying to extract the scattered halo near the source. The initial study of the X-ray halo around GX13+1 using only the ACIS-I detector done by Smith, Edgar & Shafer (2002) suffered from a lack of sensitivity within 50" of the source, limiting what conclusions could be drawn. To address this problem, observations of GX13+1 were obtained with the Chandra HRC-I and simultaneously with the RXTE PCA. Combined with the existing ACIS-I data, this allowed measurements of the X-ray halo between 2-1000". After considering a range of dust models, each assumed to be smoothly distributed with or without a dense cloud along the line of sight, the results show that there is no evidence in this data for a dense cloud near the source, as suggested by Xiang et al. (2005). In addition, although no model leads to formally acceptable results, the Weingartner & Draine (2001) and all but one of the composite grain models from Zubko, Dwek & Arendt (2004) give particularly poor fits.
Author
X RAY SCATTERING; COSMIC DUST; INTERSTELLAR MATTER; X RAY TIMING EXPLORER; HALOS; LINE OF SIGHT
20080030338 NASA Goddard Space Flight Center, Greenbelt, MD, United States
Variability of Disk Emission in Pre-Main Sequence and Related Stars. I. HD 31648 and HD 163296 - Isolated Herbig Ae Stars Driving Herbig-Haro Flows
Sitko, Michael L.; Carpenter, William J.; Kimes, Robin L.; Lynch, David K.; Russell, Ray W.; Rudy, Richard J.; Mazuk, Stephan M.; Venturini, Catherine C.; Puetter, Richard C.; Grady, Carol A.; Polomski, Elisha F.; Wisnewski, John P.; Brafford, Suellen M.; Hammel, H. B.; Perry, Raleigh B.; December 24, 2007; In English; Original contains black and white illustrations
Contract(s)/Grant(s): NNH06CC03B
Copyright; Avail.: CASI: A04, Hardcopy
Infrared photometry and spectroscopy covering a time span of a quarter century are presented for HD 31648 (MWC 480) and HD 163296 (MWC 275). Both are isolated Herbig Ae stars that exhibit signs of active accretion, including driving bipolar flows with embedded Herbig-Haro (HH) objects. HD 163296 was found to be relatively quiescent photometrically in its inner disk region, with the exception of a major increase in emitted flux in a broad wavelength region centered near 3 pm in 2002. In contrast, HD 31648 has exhibited sporadic changes in the entire 3-13 pm region throughout this span of time. In both stars the changes in the 1-5 pm flux indicate structural changes in the region of the disk near the dust sublimation zone, possibly causing its distance from the star to vary with time. Repeated thermal cycling through this region will result in the preferential survival of large grains, and an increase in the degree of crystallinity. The variability observed in these objects has important consequences for the interpretation of other types of observations. For example, source variability will compromise models based on interferometry measurements unless the interferometry observations are accompanied by nearly-simultaneous photometric data.
Author
INFRARED PHOTOMETRY; STELLAR ENVELOPES; PRE-MAIN SEQUENCE STARS; THERMAL CYCLING TESTS; PROTOPLANETARY DISKS; A STARS
20080030339 NASA Goddard Space Flight Center, Greenbelt, MD, United States
X-Ray Emitting Ejecta in Puppis A Observed with Suzaku
Hwang, U.; Petre, R.; Flanagan, K.; [2008]; In English; Original contains black and white illustrations
Copyright; Avail.: CASI: A03, Hardcopy
We report the detection and localization of X-ray emitting ejecta in the middle-aged Galactic supernova remnant Puppis A using five observations with the Suzaku X-ray Imaging Spectrometer to survey the eastern and middle portions of the remnant. A roughly 3' x 5', double-peaked region in the north center is found to be highly enriched in Si and other elements relative to the rest of the remnant. The X-ray fitted abundances are otherwise well below the solar values. While the ejecta-enhanced regions show some variation of relative element abundances, there is little evidence for a very strong enhancement of one element over the others in the imaged portion of the remnant, except possibly for a region of 0 and Ne enhancement in the remnant's south center. There is no spatial correlation between the compact [0 1111 emitting ejecta knots seen optically and the abundance enhancements seen in X-rays, although they are located in the same vicinity. The map of fitted column density shows strong variations across the remnant that echo earlier X-ray spectral hardness maps. The ionization age (as fitted for single temperature models) is sharply higher in a ridge behind the northeast-east boundary of the remnant, and is probably related to the strong molecular cloud interaction along that boundary. The temperature map, by comparison, shows relatively weak variations.
Author
EJECTA; X RAY IMAGERY; SUPERNOVA REMNANTS; MOLECULAR CLOUDS; IMAGING SPECTROMETERS; AUGMENTATION; X RAYS
20080030340 NASA Goddard Space Flight Center, Greenbelt, MD, United States
The Sensitivity of Coded Mask Telescopes
Skinner, Gerald K.; [2008]; In English; Original contains black and white illustrations
Contract(s)/Grant(s): NNG06EO90A
No Copyright; Avail.: CASI: A02, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030340
Simple formulae are often used to estimate the sensitivity of coded mask X-ray or gamma-ray telescopes, but t,hese are strictly only applicable if a number of basic assumptions are met. Complications arise, for example, if a grid structure is used to support the mask elements, if the detector spatial resolution is not good enough to completely resolve all the detail in the shadow of the mask or if any of a number of other simplifying conditions are not fulfilled. We derive more general expressions for the Poisson-noise-limited sensitivity of astronomical telescopes using the coded mask technique, noting explicitly in what circumstances they are applicable. The emphasis is on using nomenclature and techniques that result in simple and revealing results. Where no convenient expression is available a procedure is given which allows the calculation of the sensitivity. We consider certain aspects of the optimisation of the design of a coded mask telescope and show that when the detector spatial resolution and the mask to detector separation are fixed, the best source location accuracy is obtained when the mask elements are equal in size to the detector pixels.
Author
X RAY TELESCOPES; SENSITIVITY; SPATIAL RESOLUTION; GAMMA RAY TELESCOPES; CODING; OPTIMIZATION; PIXELS
20080030345 NASA Goddard Space Flight Center, Greenbelt, MD, United States; Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, United States
Comparison of Satellite-Derived and In-Situ Observations of Ice and Snow Surface Temperatures over Greenland
Hall, Dorothy K.; Box, Jason E.; Casey, Kimberly A.; Hook, Simon J.; Shuman, Christopher A.; Steffen, Konrad; [2008]; In English; Original contains color and black and white illustrations
Copyright; Avail.: CASI: A03, Hardcopy
The most practical way to get a spatially broad and continuous measurements of the surface temperature in the data-sparse cryosphere is by satellite remote sensing. The uncertainties in satellite-derived LSTs must be understood to develop internally-consistent decade-scale land-surface temperature (LST) records needed for climate studies. In this work we assess satellite-derived "clear-sky" LST products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and LSTs derived from the Enhanced Thematic Mapper Plus (ETM+) over snow and ice on Greenland. When possible, we compare satellite-derived LSTs with in-situ air-temperature observations from Greenland Climate Network (GC-Net) automatic-weather stations (AWS). We find that MODIS, ASTER and ETM+ provide reliable and consistent LSTs under clear-sky conditions and relatively-flat terrain over snow and ice targets over a range of temperatures from -40 to 0 C. The satellite-derived LSTs agree within a relative RMS uncertainty of approx.0.5 C. The good agreement among the LSTs derived from the various satellite instruments is especially notable since different spectral channels and different retrieval algorithms are used to calculate LST from the raw satellite data. The AWS record in-situ data at a "point" while the satellite instruments record data over an area varying in size from: 57 X 57 m (ETM+), 90 X 90 m (ASTER), or to 1 X 1 km (MODIS). Surface topography and other factors contribute to variability of LST within a pixel, thus the AWS measurements may not be representative of the LST of the pixel. Without more information on the local spatial patterns of LST, the AWS LST cannot be considered valid ground truth for the satellite measurements, with RMS uncertainty approx.2 C. Despite the relatively large AWS-derived uncertainty, we find LST data are characterized by high accuracy but have uncertain absolute precision.
Author
CRYOSPHERES; SURFACE TEMPERATURE; TEMPERATURE MEASUREMENT; REMOTE SENSING; MODIS (RADIOMETRY); THEMATIC MAPPERS (LANDSAT); THERMAL EMISSION
20080030359 NASA Goddard Space Flight Center, Greenbelt, MD, United States
Regional Similarity of Leveed Lava Flows on the Mars Plains
Baloga, Steve M.; Glaze, Lori, S.; March 10, 2008; In English; Lunar and Planetary Science Conference, 10-14 Mar. 2008, Houston, TX, United States; Original contains black and white illustrations
Copyright; Avail.: CASI: A01, Hardcopy
The dynamics of lava flow movement are controlled by the fluid interior. Crust, solids, and nondeformable material can only retard the advance or spreading of a lava flow. Figure 1 shows a typical large, channelized lava flow found on the Mars plains. It has been suggested in [I] that such large leveed flows on the Mars plains were emplaced by a balance between the formation and shedding of crust as the flow advances. For the prototypical flow north of Pavonis Mons (Fig. I), such a balance leads to a flow morphology that approximately self-replicates at all locations along the flow path [2,3]. Moreover, most quantitative characteristics of emplacement (e.g., viscosity, volumetric flow rate) of the prototype flow at Pavonis Mons resembled those of large channelized lava flows on Earth. The exception was the relatively long, sustained supply of lava, on the order of a year as opposed to hours or days for terrestrial analogs.
Derived from text
LAVA; MARS SURFACE; MARS VOLCANOES; PLANETARY GEOLOGY; FLUID FLOW; CRUSTS; CHANNEL FLOW
20080030363 NASA Goddard Space Flight Center, Greenbelt, MD, United States
Spatial and Alignment Analyses for a field of Small Volcanic Vents South of Pavonis Mons Mars
Bleacher, J. E.; Glaze, L. S.; Greeley, R.; Hauber, E.; Baloga, S. M.; Sakimoto, S. E. H.; Williams, D. A.; Glotch, T. D.; March 10, 2008; In English; 37th Lunar and Planetary Science Conference, 10-14 Mar. 2008, Houston, TX, United States; Original contains black and white illustrations
Copyright; Avail.: CASI: A01, Hardcopy
The Tharsis province of Mars displays a variety of small volcanic vent (10s krn in diameter) morphologies. These features were identified in Mariner and Viking images [1-4], and Mars Orbiter Laser Altimeter (MOLA) data show them to be more abundant than originally observed [5,6]. Recent studies are classifying their diverse morphologies [7-9]. Building on this work, we are mapping the location of small volcanic vents (small-vents) in the Tharsis province using MOLA, Thermal Emission Imaging System, and High Resolution Stereo Camera data [10]. Here we report on a preliminary study of the spatial and alignment relationships between small-vents south of Pavonis Mons, as determined by nearest neighbor and two-point azimuth statistical analyses. Terrestrial monogenetic volcanic fields display four fundamental characteristics: 1) recurrence rates of eruptions,2 ) vent abundance, 3) vent distribution, and 4) tectonic relationships [11]. While understanding recurrence rates typically requires field measurements, insight into vent abundance, distribution, and tectonic relationships can be established by mapping of remotely sensed data, and subsequent application of spatial statistical studies [11,12], the goal of which is to link the distribution of vents to causal processes.
Author
SPATIAL DISTRIBUTION; MARS VOLCANOES; THERMAL EMISSION; TECTONICS; REMOTE SENSING; MARS GLOBAL SURVEYOR; DISPLAY DEVICES
20080030366 Perot Systems Corp., Greenbelt, MD, United States
DC/DC Converter Stability Testing Study
Wang, Bright L.; July 2008; In English; Original contains color illustrations
Contract(s)/Grant(s): ESES 260GSS-05-S-246
Report No.(s): NASA/CR-2008-214163; No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030366
This report presents study results on hybrid DC/DC converter stability testing methods. An input impedance measurement method and a gain/phase margin measurement method were evaluated to be effective to determine front-end oscillation and feedback loop oscillation. In particular, certain channel power levels of converter input noises have been found to have high degree correlation with the gain/phase margins. It becomes a potential new method to evaluate stability levels of all type of DC/DC converters by utilizing the spectral analysis on converter input noises.
Author
VOLTAGE CONVERTERS (DC TO DC); IMPEDANCE MEASUREMENT; STABILITY TESTS; SPECTRUM ANALYSIS
20080030370 NASA Dryden Flight Research Center, Edwards, CA, United States
Detection and Characterization of Boundary-Layer Transition in Flight at Supersonic Conditions Using Infrared Thermography
Banks, Daniel W.; July 2008; In English; 13th International Symposium on Flow Visualization, 1-4 Jul. 2008, Nice, France; Original contains color and black and white illustrations
No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030370
Infrared thermography is a powerful tool for investigating fluid mechanics on flight vehicles. (Can be used to visualize and characterize transition, shock impingement, separation etc.). Updated onboard F-15 based system was used to visualize supersonic boundary layer transition test article. (Tollmien-Schlichting and cross-flow dominant flow fields). Digital Recording improves image quality and analysis capability. (Allows accurate quantitative (temperature) measurements, Greater enhancement through image processing allows analysis of smaller scale phenomena).
Author
INFRARED RADIATION; THERMOGRAPHY; FLUID MECHANICS; F-15 AIRCRAFT; DIGITAL SYSTEMS; DATA RECORDING; IMAGE PROCESSING; TEMPERATURE MEASUREMENT; SUPERSONIC BOUNDARY LAYERS
20080030371 NASA Langley Research Center, Hampton, VA, United States
Modeling the Non-Linear Response of Fiber-Reinforced Laminates Using a Combined Damage/Plasticity Model
Schuecker, Clara; Davila, Carlos G.; Pettermann, Heinz E.; July 2008; In English; Original contains color and black and white illustrations
Contract(s)/Grant(s): WBS 698259.02.07.07.03.03
Report No.(s): NASA/TM-2008-215314; L-19487; Copyright; Avail.: CASI: A03, Hardcopy
The present work is concerned with modeling the non-linear response of fiber reinforced polymer laminates. Recent experimental data suggests that the non-linearity is not only caused by matrix cracking but also by matrix plasticity due to shear stresses. To capture the effects of those two mechanisms, a model combining a plasticity formulation with continuum damage has been developed to simulate the non-linear response of laminates under plane stress states. The model is used to compare the predicted behavior of various laminate lay-ups to experimental data from the literature by looking at the degradation of axial modulus and Poisson s ratio of the laminates. The influence of residual curing stresses and in-situ effect on the predicted response is also investigated. It is shown that predictions of the combined damage/plasticity model, in general, correlate well with the experimental data. The test data shows that there are two different mechanisms that can have opposite effects on the degradation of the laminate Poisson s ratio which is captured correctly by the damage/plasticity model. Residual curing stresses are found to have a minor influence on the predicted response for the cases considered here. Some open questions remain regarding the prediction of damage onset.
Author
FIBER COMPOSITES; CAPTURE EFFECT; RESIDUAL STRESS; SHEAR STRESS; DEGRADATION; LAMINATES; PLASTIC PROPERTIES
20080030372 NASA Glenn Research Center, Cleveland, OH, United States
Wave Propagation Through Inhomogeneities With Applications to Novel Sensing Techniques
Adamovsky, G.; Tokars, R.; Varga, D.; Floyd B.; June 2008; In English; 46th AIAA Aerospace Science Meeting and Exhibit, 7-10 jan. 2008, Reno, NV, United States; Original contains color and black and white illustrations
Contract(s)/Grant(s): WBS 599489.02.07.03.06.02.01
Report No.(s): NASA/TM-2008-215185; AIAA Paper-2008-255; E-16429; Copyright; Avail.: CASI: A03, Hardcopy
The paper describes phenomena observed as a result of laser pencil beam interactions with abrupt interfaces including aerodynamic shocks. Based on these phenomena, a novel flow visualization technique based on a laser scanning pencil beam is introduced. The technique reveals properties of light interaction with interfaces including aerodynamic shocks that are not seen using conventional visualization. Various configurations of scanning beam devices including those with no moving parts, as well as results of "proof-of-concept" tests, are included.
Author
BEAM INTERACTIONS; FLOW VISUALIZATION; LASER BEAMS; WAVE PROPAGATION; LASER APPLICATIONS; PENCIL BEAMS
20080030373 NASA Glenn Research Center, Cleveland, OH, United States
Using COMSOL Multiphysics Software to Model Anisotropic Dielectric and Metamaterial Effects in Folded-Waveguide Traveling-Wave Tube Slow-Wave Circuits
Starinshak, David P.; Smith, Nathan D.; Wilson, Jeffrey D.; July 2008; In English; Ninth International Vacuum Electronics Conference (IVEC 2008), 22-24 Apr. 2008, Monterey, CA, United States; Original contains color illustrations
Contract(s)/Grant(s): WBS 698671.01.03.45; WBS 526282.01.03.02.03.04
Report No.(s): NASA/TM-2008-215267; P1.35; E-16537; Copyright; Avail.: CASI: A02, Hardcopy
The electromagnetic effects of conventional dielectrics, anisotropic dielectrics, and metamaterials were modeled in a terahertz-frequency folded-waveguide slow-wave circuit. Results of attempts to utilize these materials to increase efficiency are presented.
Author
DIELECTRICS; WAVE PROPAGATION; ANISOTROPY; FINITE ELEMENT METHOD; DIELECTRIC PROPERTIES
20080030374 NASA Langley Research Center, Hampton, VA, United States
Assessment of the Visible Channel Calibrations of the TRMM VIRS and MODIS on Aqua and Terra
Minnis, Patrick; Doelling, David R.; Nguyen, Louis; Miller, Walter F.; Chakrapani, Venketesan; April 2007; In English; Original contains color and black and white illustrations
Contract(s)/Grant(s): WBS 720817.04.07.01
Copyright; Avail.: CASI: A04, Hardcopy
Several recent research satellites carry self-calibrating multispectral imagers that can be used for calibrating operational imagers lacking complete self-calibrating capabilities. In particular, the visible (VIS, 0.65 m) channels on operational meteorological satellites are generally calibrated before launch, but require vicarious calibration techniques to monitor the gains and offsets once they are in orbit. To ensure that the self-calibrating instruments are performing as expected, this paper examines the consistencies between the VIS channel (channel 1) reflectances of the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra and Aqua satellites and the Version 5a and 6 reflectances of the Visible Infrared Scanner (VIRS) on the Tropical Rainfall Measuring Mission using a variety of techniques. These include comparisons of Terra and Aqua VIS radiances with coincident broadband shortwave radiances from the well-calibrated Clouds and the Earth s Radiant Energy System (CERES), time series of deep convective cloud (DCC) albedos, and ray-matching intercalibrations between each of the three satellites. Time series of matched Terra and VIRS data, Aqua and VIRS data, and DCC reflected fluxes reveal that an older version (Version 5a, ending in early 2004) of the VIRS calibration produced a highly stable record, while the latest version (Version 6) appears to overestimate the sensor gain change by approx.1%/y as the result of a manually induced gain adjustment. Comparisons with the CERES shortwave radiances unearthed a sudden change in the Terra MODIS calibration that caused a 1.17% decrease in the gain on 19 November 2003 that can be easily reversed. After correction for these manual adjustments, the trends in the VIRS and Terra channels are no greater than 0.1%/y. Although the results were more ambiguous, no statistically significant trends were found in the Aqua MODIS channel-1 gain. The Aqua radiances are 1% greater, on average, than their Terra counterparts, and after normalization are 4.6% greater than VIRS radiances, in agreement with theoretical calculations. The discrepancy between the two MODIS instruments should be taken into account to ensure consistency between parameters derived from them. With the adjustments, any of the three instruments can serve as references for calibrating other satellites. Monitoring of the calibrations continues in near-real-time and the results are available via the world wide web.
Author
METEOROLOGICAL SATELLITES; MODIS (RADIOMETRY); TRMM SATELLITE; CALIBRATING; INTERCALIBRATION; REAL TIME OPERATION; AQUA SPACECRAFT; TERRA SPACECRAFT; BROADBAND; IMAGING SPECTROMETERS
20080030375 NASA Langley Research Center, Hampton, VA, United States
Design of a Mars Airplane Propulsion System for the Aerial Regional-Scale Environmental Survey (ARES) Mission Concept
Kuhl, Christopher A.; July 20, 2008; In English; 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 20-23 Jul. 2008, Hartford, CT, United States; Original contains color and black and white illustrations
Contract(s)/Grant(s): WBS 698671.02.07.02.01
No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030375
The Aerial Regional-Scale Environmental Survey (ARES) is a Mars exploration mission concept that utilizes a rocket propelled airplane to take scientific measurements of atmospheric, surface, and subsurface phenomena. The liquid rocket propulsion system design has matured through several design cycles and trade studies since the inception of the ARES concept in 2002. This paper describes the process of selecting a bipropellant system over other propulsion system options, and provides details on the rocket system design, thrusters, propellant tank and PMD design, propellant isolation, and flow control hardware. The paper also summarizes computer model results of thruster plume interactions and simulated flight performance. The airplane has a 6.25 m wingspan with a total wet mass of 185 kg and has to ability to fly over 600 km through the atmosphere of Mars with 45 kg of MMH / MON3 propellant.
Author
LIQUID ROCKET PROPELLANTS; FLIGHT CHARACTERISTICS; ROCKET ENGINES; MARS ATMOSPHERE; MARS EXPLORATION; SYSTEMS ENGINEERING; COMPUTERIZED SIMULATION
Additions to the NASA Aeronautics and Space Database as of 08/21/2008
20080030791 TechLand Research, Inc., North Olmstead, OH, United States
Aerodynamic Design of a Dual-Flow Mach 7 Hypersonic Inlet System for a Turbine-Based Combined-Cycle Hypersonic Propulsion System
Sanders, Bobby W.; Weir, Lois J.; June 2008; In English; Original contains black and white illustrations
Contract(s)/Grant(s): NAS3-03110WBS 599489.02.07.03.07.02.02
Report No.(s): NASA/CR-2008-215214; E-16505; TRR-121507; No Copyright; Avail.: CASI: A05, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030791
A new hypersonic inlet for a turbine-based combined-cycle (TBCC) engine has been designed. This split-flow inlet is designed to provide flow to an over-under propulsion system with turbofan and dual-mode scramjet engines for flight from takeoff to Mach 7. It utilizes a variable-geometry ramp, high-speed cowl lip rotation, and a rotating low-speed cowl that serves as a splitter to divide the flow between the low-speed turbofan and the high-speed scramjet and to isolate the turbofan at high Mach numbers. The low-speed inlet was designed for Mach 4, the maximum mode transition Mach number. Integration of the Mach 4 inlet into the Mach 7 inlet imposed significant constraints on the low-speed inlet design, including a large amount of internal compression. The inlet design was used to develop mechanical designs for two inlet mode transition test models: small-scale (IMX) and large-scale (LIMX) research models. The large-scale model is designed to facilitate multi-phase testing including inlet mode transition and inlet performance assessment, controls development, and integrated systems testing with turbofan and scramjet engines.
Author
SUPERSONIC COMBUSTION RAMJET ENGINES; HYPERSONIC INLETS; ENGINE INLETS; CONTROL SYSTEMS DESIGN; HYPERSONIC FLIGHT; SUPERSONIC SPEED; TURBOFAN ENGINES
20080030792 ASRC Aerospace Corp., Cleveland, OH, United States
Effects of a Rotating Aerodynamic Probe on the Flow Field of a Compressor Rotor
Lepicovsky, Jan; June 2008; In English; Original contains color illustrations
Contract(s)/Grant(s): NNC06BA07B561581.02.08.03.21.02
Report No.(s): NASA/CR-2008-215215; E-16503; No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030792
An investigation of distortions of the rotor exit flow field caused by an aerodynamic probe mounted in the rotor is described in this paper. A rotor total pressure Kiel probe, mounted on the rotor hub and extending up to the mid-span radius of a rotor blade channel, generates a wake that forms additional flow blockage. Three types of high-response aerodynamic probes were used to investigate the distorted flow field behind the rotor. These probes were: a split-fiber thermo-anemometric probe to measure velocity and flow direction, a total pressure probe, and a disk probe for in-flow static pressure measurement. The signals acquired from these high-response probes were reduced using an ensemble averaging method based on a once per rotor revolution signal. The rotor ensemble averages were combined to construct contour plots for each rotor channel of the rotor tested. In order to quantify the rotor probe effects, the contour plots for each individual rotor blade passage were averaged into a single value. The distribution of these average values along the rotor circumference is a measure of changes in the rotor exit flow field due to the presence of a probe in the rotor. These distributions were generated for axial flow velocity and for static pressure.
Author
AERODYNAMIC CHARACTERISTICS; AXIAL FLOW; COMPRESSOR ROTORS; FLOW MEASUREMENT; FLOW DISTRIBUTION; STATIC PRESSURE; FLUID FLOW
20080030793 NASA Glenn Research Center, Cleveland, OH, United States
Aircraft Engine On-Line Diagnostics Through Dual-Channel Sensor Measurements: Development of a Baseline System
Kobayashi, Takahisa; Simon, Donald L.; June 2008; In English; ASME Turbo Expo 2008 Gas Turbine Congress and Exposition, 9-13 Jun. 2008, Berlin, Germany; Original contains color illustrations
Contract(s)/Grant(s): NNCO6BA07BWBS 645846.02.07.03.03.01
Report No.(s): NASA/TM-2008-215228; GT2008-50345; E-16515; No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030793
In this paper, a baseline system which utilizes dual-channel sensor measurements for aircraft engine on-line diagnostics is developed. This system is composed of a linear on-board engine model (LOBEM) and fault detection and isolation (FDI) logic. The LOBEM provides the analytical third channel against which the dual-channel measurements are compared. When the discrepancy among the triplex channels exceeds a tolerance level, the FDI logic determines the cause of the discrepancy. Through this approach, the baseline system achieves the following objectives: (1) anomaly detection, (2) component fault detection, and (3) sensor fault detection and isolation. The performance of the baseline system is evaluated in a simulation environment using faults in sensors and components.
Author
FAULT DETECTION; DIAGNOSIS; ON-LINE SYSTEMS; AIRCRAFT ENGINES
20080030794 NASA Glenn Research Center, Cleveland, OH, United States
Low Frequency Noise Contamination in Fan Model Testing
Brown, Clifford A.; Schifter, Nicholas A.; June 2008; In English; ASME Turbo Expo 2008 Gas Turbine Congress and Exposition, 9-13 Jun. 2008, Berlin, Germany; Original contains color illustrations
Contract(s)/Grant(s): WBS 984754.02.07.03.17.03
Report No.(s): NASA/TM-2008-215255; GT2008-50850; E-16517; No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030794
Aircraft engine noise research and development depends on the ability to study and predict the noise created by each engine component in isolation. The presence of a downstream pylon for a model fan test, however, may result in noise contamination through pylon interactions with the free stream and model exhaust airflows. Additionally, there is the problem of separating the fan and jet noise components generated by the model fan. A methodology was therefore developed to improve the data quality for the 9 15 Low Speed Wind Tunnel (LSWT) at the NASA Glenn Research Center that identifies three noise sources: fan noise, jet noise, and rig noise. The jet noise and rig noise were then measured by mounting a scale model of the 9 15 LSWT model fan installation in a jet rig to simulate everything except the rotating machinery and in duct components of fan noise. The data showed that the spectra measured in the LSWT has a strong rig noise component at frequencies as high as 3 kHz depending on the fan and airflow fan exit velocity. The jet noise was determined to be significantly lower than the rig noise (i.e., noise generated by flow interaction with the downstream support pylon). A mathematical model for the rig noise was then developed using a multi-dimensional least squares fit to the rig noise data. This allows the rig noise to be subtracted or removed, depending on the amplitude of the rig noise relative to the fan noise, at any given frequency, observer angle, or nozzle pressure ratio. The impact of isolating the fan noise with this method on spectra, overall power level (OAPWL), and Effective Perceived Noise Level (EPNL) is studied.
Author
AERODYNAMIC NOISE; JET AIRCRAFT NOISE; EFFECTIVE PERCEIVED NOISE LEVELS; PRESSURE RATIO; NOISE INTENSITY; ENGINE NOISE; AIR FLOW; AIRCRAFT MODELS
20080030795 NASA Glenn Research Center, Cleveland, OH, United States
The Need for High Fidelity Lunar Regolith Simulants
Gaier, James R.; June 2008; In English; Space Resources Roundtable IX, 25-27 Oct. 2008, Golden, CO, United States; Original contains black and white illustrations
Contract(s)/Grant(s): WBS 936374.03.03.03
Report No.(s): NASA/TM-2008-215261; E-16528; No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030795
The case is made for the need to have high fidelity lunar regolith simulants to verify the performance of structures, mechanisms, and processes to be used on the lunar surface. Minor constituents will in some cases have major consequences. Small amounts of sulfur in the regolith can poison catalysts, and metallic iron on the surface of nano-sized dust particles may cause a dramatic increase in its toxicity. So the definition of a high fidelity simulant is application-dependent. For example, in situ resource utilization will require high fidelity in chemistry, meaning careful attention to the minor components and phases; but some other applications, such as the abrasive effects on suit fabrics, might be relatively insensitive to minor component chemistry while abrasion of some metal components may be highly dependent on trace components. The lunar environment itself will change the surface chemistry of the simulant, so to have a high fidelity simulant it must be used in a high fidelity simulated environment to get an accurate simulation. Research must be conducted to determine how sensitive technologies will be to minor components and environmental factors before they can be dismissed as unimportant.
Author
LUNAR ENVIRONMENT; LUNAR ROCKS; LUNAR SURFACE; SURFACE REACTIONS; ABRASION; CHEMICAL REACTIONS; DUST
20080030796 NASA Langley Research Center, Hampton, VA, United States
Vibroacoustic Response Data of Stiffened Panels and Cylinders
July 28, 2008; In English; Noise-Con 2008, 28-31 Jul. 2008, Dearborn, MI, United States; Original contains color and black and white illustrations
Contract(s)/Grant(s): WBS 877868.02.07.07.04.01
No Copyright; Avail.: CASI: A02, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030796
NASA has collected vibroacoustic response data on a variety of complex, aerospace structures to support research into numerical modeling of such structures. This data is being made available to the modeling community to promote the development and validation of analysis methods for these types of structures. Existing data from two structures is described, as well as plans for a data set from a third structure. The first structure is a 1.22 m by 1.22 m stiffened aluminum panel, typical of a commercial aircraft sidewall section. The second is an enclosed, stiffened aluminum cylinder, approximately 3.66 m long and 1.22 m in diameter, constructed to resemble a small aircraft fuselage with no windows and a periodic structure. The third structure is a filament-wound composite cylinder with composite stiffeners. Numerous combinations of excitation and response variables were measured on the structures, including: shaker excitation; diffuse acoustic field; velocity response from a laser vibrometer; intensity scans; and point acceleration.
Author
ACOUSTICS; VIBRATIONAL STRESS; SOUND FIELDS; AIRCRAFT STRUCTURES; MATHEMATICAL MODELS; FUSELAGES
20080030797 NASA Langley Research Center, Hampton, VA, United States
Vibration Response Models of a Stiffened Aluminum Plate Excited by a Shaker
Cabell, Randolph H.; July 28, 2008; In English; Noise-Con 2008, 28-31 Jul. 2008, Dearborn, MI, United States; Original contains color and black and white illustrations
Contract(s)/Grant(s): WBS 877868.02.07.07.04.01
No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030797
Numerical models of structural-acoustic interactions are of interest to aircraft designers and the space program. This paper describes a comparison between two energy finite element codes, a statistical energy analysis code, a structural finite element code, and the experimentally measured response of a stiffened aluminum plate excited by a shaker. Different methods for modeling the stiffeners and the power input from the shaker are discussed. The results show that the energy codes (energy finite element and statistical energy analysis) accurately predicted the measured mean square velocity of the plate. In addition, predictions from an energy finite element code had the best spatial correlation with measured velocities. However, predictions from a considerably simpler, single subsystem, statistical energy analysis model also correlated well with the spatial velocity distribution. The results highlight a need for further work to understand the relationship between modeling assumptions and the prediction results.
Author
VIBRATION; SPACE PROGRAMS; DYNAMIC STRUCTURAL ANALYSIS; ACOUSTICS; MEAN SQUARE VALUES; FINITE ELEMENT METHOD
Additions to the NASA Aeronautics and Space Database as of 08/22/2008
20080030947 NASA Langley Research Center, Hampton, VA, United States
Design of an Indoor Sonic Boom Simulator at NASA Langley Research Center
Klos, Jacob; Sullivan, Brenda M.; Shepherd, Kevin P.; July 28, 2008; In English; Noise-Con 2008, 28-31 Jul. 2008, Dearborn, MI, United States; Original contains color illustrations
Contract(s)/Grant(s): WBS 984754.02.07.07.18.02
No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030947
Construction of a simulator to recreate the soundscape inside residential buildings exposed to sonic booms is scheduled to start during the summer of 2008 at NASA Langley Research Center. The new facility should be complete by the end of the year. The design of the simulator allows independent control of several factors that create the indoor soundscape. Variables that will be isolated include such factors as boom duration, overpressure, rise time, spectral shape, level of rattle, level of squeak, source of rattle and squeak, level of vibration and source of vibration. Test subjects inside the simulator will be asked to judge the simulated soundscape, which will represent realistic indoor boom exposure. Ultimately, this simulator will be used to develop a functional relationship between human response and the sound characteristics creating the indoor soundscape. A conceptual design has been developed by NASA personnel, and is currently being vetted through small-scale risk reduction tests that are being performed in-house. The purpose of this document is to introduce the conceptual design, identify how the indoor response will be simulated, briefly outline some of the risk reduction tests that have been completed to vet the design, and discuss the impact of these tests on the simulator design.
Author
SONIC BOOMS; SIMULATORS; VIBRATION; BUILDINGS; EXPOSURE; CONSTRUCTION; OVERPRESSURE
20080030948 NASA Langley Research Center, Hampton, VA, United States; Northrop Grumman Corp., El Segundo, CA, United States
Evaluation of Composite Structures Technologies for Application to NASA's Vision for Space Exploration (CoSTS)
Deo, Ravi; Wang, Donny; Bohlen, Jim; Fukuda, Cliff; July 2008; In English; Original contains color and black and white illustrations
Contract(s)/Grant(s): NNL04AA13BWBS 441261.04.23.04.04
Report No.(s): NASA/CR-2008-215333; No Copyright; Avail.: CASI: A04, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030948
A trade study was conducted to determine the suitability of composite structures for weight and life cycle cost savings in primary and secondary structural systems for crew exploration vehicles, crew and cargo launch vehicles, landers, rovers, and habitats. The results of the trade study were used to identify and rank order composite material technologies that can have a near-term impact on a broad range of exploration mission applications. This report recommends technologies that should be developed to enable usage of composites on Vision for Space Exploration vehicles towards mass and life-cycle cost savings.
Author
COMPOSITE MATERIALS; COMPOSITE STRUCTURES; COST REDUCTION; LIFE CYCLE COSTS; HABITATS
20080030949 Boeing Phantom Works, Huntington Beach, CA, United States
Evaluation of Advanced Composite Structures Technologies for Application to NASA's Vision for Space Exploration
Messinger, Ross; July 2008; In English; Original contains color and black and white illustrations
Contract(s)/Grant(s): NNL04AA11BWBS 441261.04.23.04.04
Report No.(s): NASA/CR-2008-215120; No Copyright; Avail.: CASI: A07, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030949
An assessment was performed to identify the applicability of composite material technologies to major structural elements of the NASA Constellation program. A qualitative technology assessment methodology was developed to document the relative benefit of 24 structural systems with respect to 33 major structural elements of Ares I, Orion, Ares V, and Altair. Technology maturity assessments and development plans were obtained from more than 30 Boeing subject matter experts for more than 100 technologies. These assessment results and technology plans were combined to generate a four-level hierarchy of recommendations. An overarching strategy is suggested, followed by a Constellation-wide development plan, three integrated technology demonstrations, and three focused projects for a task order follow-on.
Author
CONSTELLATION PROGRAM; COMPOSITE STRUCTURES; COMPOSITE MATERIALS; TECHNOLOGY ASSESSMENT
20080030950 NASA Langley Research Center, Hampton, VA, United States
NASA Earth Observations Informing Renewable Energy Management and Policy Decision Making
Eckman, Richard S.; Stackhouse, Paul W., Jr.; January 2008; In English; World Renewable Energy Congress X, 19-25 Jul. 2008, Glasgow, United Kingdom; Original contains black and white illustrations
Contract(s)/Grant(s): WBS 389018.02.15.02.11
No Copyright; Avail.: CASI: A01, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080030950
The NASA Applied Sciences Program partners with domestic and international governmental organizations, universities, and private entities to improve their decisions and assessments. These improvements are enabled by using the knowledge generated from research resulting from spacecraft observations and model predictions conducted by NASA and providing these as inputs to the decision support and scenario assessment tools used by partner organizations. The Program is divided into eight societal benefit areas, aligned in general with the Global Earth Observation System of Systems (GEOSS) themes. The Climate Application of the Applied Sciences Program has as one of its focuses, efforts to provide for improved decisions and assessments in the areas of renewable energy technologies, energy efficiency, and climate change impacts. The goals of the Applied Sciences Program are aligned with national initiatives such as the U.S. Climate Change Science and Technology Programs and with those of international organizations including the Group on Earth Observations (GEO) and the Committee on Earth Observation Satellites (CEOS). Activities within the Program are funded principally through proposals submitted in response to annual solicitations and reviewed by peers.
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DECISION MAKING; RENEWABLE ENERGY; NASA PROGRAMS; CLIMATOLOGY; ENERGY TECHNOLOGY
Additions to the NASA Aeronautics and Space Database as of 08/25/2008
20080031037 Boeing Co., Renton, WA, United States; NASA Marshall Space Flight Center, Huntsville, AL, United States
MISSE Thermal Control Materials with Comparison to Previous Flight Experiments
Finckenor, Miria; Pippin, H. Gary; Frey, George; May 20, 2008; In English; The Ninth International Space Conference- Protection of Materials and Structures from the Space Environment, 20-23 May 2008, Toronto, Canada; Original contains black and white illustrations
Copyright; Avail.: CASI: A02, Hardcopy
Many different passive thermal control materials were flown as part of the Materials on International Space Station Experiment (MISSE), including inorganic coatings, anodized aluminum, and multi-layer insulation materials. These and other material samples were exposed to the low Earth orbital environment of atomic oxygen, ultraviolet radiation, thermal cycling, and hard vacuum, though atomic oxygen exposure was limited for some samples. Materials flown on MISSE-1 and MISSE-2 were exposed to the space environment for nearly four years. Materials flown on MISSE-3, MISSE-4, and MISSE-5 were exposed to the space environment for one year. Solar absorptance, infrared emittance, and mass measurements indicate the durability of these materials to withstand the space environment. Effects of short duration versus long duration exposure on ISS are explored, as well as comparable data from previous flight experiments, such as the Passive Optical Sample Assembly (POSA), Optical Properties Monitor (OPM), and Long Duration Exposure Facility (LDEF).
Author
INTERNATIONAL SPACE STATION; THERMAL CONTROL COATINGS; EXTRATERRESTRIAL ENVIRONMENTS; DURABILITY; PHYSICAL PROPERTIES; SPACEBORNE EXPERIMENTS; TEMPERATURE CONTROL
20080031048 Auburn Univ., AL, United States; Entech, Inc., Keller, TX, United States; NASA Glenn Research Center, Cleveland, OH, United States; NASA Marshall Space Flight Center, Huntsville, AL, United States
A SEP Mission to Jupiter Using the Stretched Lens Array
Brandhorst, Henry W.; Rodiek, Julie A.; Ferguson, Dale C.; O'Neill, Mark J.; Piszczor, Michael F.; Oleson, Steve; May 05, 2008; In English; Space Propulsion 2008: 5th International Spacecraft Propulsion Conference and 2nd International Symposium on Propulsion for Space Transportation, 5-9 May 2008, Herakilon, Crete, Greece; Original contains black and white illustrations
Copyright; Avail.: CASI: A01, Hardcopy
As space exploration continues to be a primary focus of NASA, solar electric propulsion (SEP) becomes a forerunner in the mode of transportation to reach other planets in our solar system. Several critical issues emerge as potential barriers to this approach such as reducing solar array radiation damage, operating the array at high voltage (>300 V) for extended times for Hall or ion thrusters, and designing an array that will be resistant to micrometeoroid impacts and the differing environmental conditions as the vehicle travels further into space. It is also of great importance to produce an array that is light weight to preserve payload mass fraction and to do this at a cost that is lower than today's arrays. This paper will describe progress on an array that meets all these requirements and will detail its use in a solar electric mission to Jupiter. From 1998-2001, NASA flew the Deep Space 1 mission that validated the use of ion propulsion for extended space missions. This highly successful two-year mission also used a novel SCARLET solar array that concentrated sunlight eight-fold onto small area solar cells. This array performed flawlessly and within 2% of its projected performance over the entire mission. That design has evolved into the Stretched Lens Array (SLA) shown in figure 1. The primary difference between SCARLET and the SLA is that no additional glass cover is used over the silicone lens. This has led to significant mass, cost and complexity reductions. The module shown in figure 1 is the latest version of the design. This design leads to a specific power exceeding 300 W/kg at voltages exceeding 300 V. In addition, this module has been tested to voltages over 1000 V while under hypervelocity particle impact in a plasma environment with no arcing. Furthermore array segments are under test for corona breakdown that can become a critical issue for long term, high voltage missions.
Author
SOLAR ELECTRIC PROPULSION; ION PROPULSION; SPACE MISSIONS; SPACE EXPLORATION; HALL THRUSTERS; DEEP SPACE 1 MISSION; SOLAR ARRAYS; LENSES; MICROMETEOROIDS; HYPERVELOCITY IMPACT
20080031061 NASA Marshall Space Flight Center, Huntsville, AL, United States
Health and Environment Linked for Information Exchange (HELIX)-Atlanta: A CDC-NASA Joint Environmental Public Health Tracking Collaborative Project
Al-Hamdan, Mohammad; Luvall, Jeff; May 16, 2008; In English; American Thoracic Society's (ATS) 2008 Toronto International Conference/ATS, 16-21 May 2008, Ontario, Canada; Original contains black and white illustrations
Copyright; Avail.: CASI: A01, Hardcopy
HELIX-Atlanta was developed to support current and future state and local EPHT programs to implement data linking demonstration projects which could be part of the CDC EPHT Network. HELIX-Atlanta is a pilot linking project in Atlanta for CDC to learn about the challenges the states will encounter. NASA/MSFC and the CDC are partners in linking environmental and health data to enhance public health surveillance. ~ The use of NASA technology creates value added geospatial products from existing environmental data sources to facilitate public health linkages. Proving the feasibility of the approach is the main objective
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PUBLIC HEALTH; SURVEILLANCE; HEALTH; ENVIRONMENTAL QUALITY
Additions to the NASA Aeronautics and Space Database as of 08/26/2008
20080031096 NASA Langley Research Center, Hampton, VA, United States
Fatigue Crack Growth Threshold Testing of Metallic Rotorcraft Materials
Newman, John A.; James, Mark A.; Johnson, William M.; Le, Dy D.; July 2008; In English; Original contains black and white illustrations
Contract(s)/Grant(s): WBS 698259.02.07.07.03.02
Report No.(s): NASA/TM-2008-215331; ARL-TR-4472; L-19489; Copyright; Avail.: CASI: A03, Hardcopy
Results are presented for a program to determine the near-threshold fatigue crack growth behavior appropriate for metallic rotorcraft alloys. Four alloys, all commonly used in the manufacture of rotorcraft, were selected for study: Aluminum alloy 7050, 4340 steel, AZ91E Magnesium, and Titanium alloy Ti-6Al-4V (beta-STOA). The Federal Aviation Administration (FAA) sponsored this research to advance efforts to incorporate damage tolerance design and analysis as requirements for rotorcraft certification. Rotorcraft components are subjected to high cycle fatigue and are typically subjected to higher stresses and more stress cycles per flight hour than fixed-wing aircraft components. Fatigue lives of rotorcraft components are generally spent initiating small fatigue cracks that propagate slowly under near-threshold cracktip loading conditions. For these components, the fatigue life is very sensitive to the near-threshold characteristics of the material.
Author
CRACK PROPAGATION; FATIGUE (MATERIALS); ROTARY WING AIRCRAFT; TOLERANCES (MECHANICS); FATIGUE LIFE; METAL FATIGUE
20080031110 NASA Langley Research Center, Hampton, VA, United States
Modifications to Axially Symmetric Simulations Using New DSMC (2007) Algorithms
Liechty, Derek S.; July 21, 2008; In English; 26th Rarefied Gas Dynamics Conference, 21-25 Jul. 2008, Kyoto, Japan; Original contains color and black and white illustrations
Contract(s)/Grant(s): WBS 52628201070405
No Copyright; Avail.: CASI: A02, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031110
Several modifications aimed at improving physical accuracy are proposed for solving axially symmetric problems building on the DSMC (2007) algorithms introduced by Bird. Originally developed to solve nonequilibrium, rarefied flows, the DSMC method is now regularly used to solve complex problems over a wide range of Knudsen numbers. These new algorithms include features such as nearest neighbor collisions excluding the previous collision partners, separate collision and sampling cells, automatically adaptive variable time steps, a modified no-time counter procedure for collisions, and discontinuous and event-driven physical processes. Axially symmetric solutions require radial weighting for the simulated molecules since the molecules near the axis represent fewer real molecules than those farther away from the axis due to the difference in volume of the cells. In the present methodology, these radial weighting factors are continuous, linear functions that vary with the radial position of each simulated molecule. It is shown that how one defines the number of tentative collisions greatly influences the mean collision time near the axis. The method by which the grid is treated for axially symmetric problems also plays an important role near the axis, especially for scalar pressure. A new method to treat how the molecules are traced through the grid is proposed to alleviate the decrease in scalar pressure at the axis near the surface. Also, a modification to the duplication buffer is proposed to vary the duplicated molecular velocities while retaining the molecular kinetic energy and axially symmetric nature of the problem.
Author
AXISYMMETRIC FLOW; ALGORITHMS; MONTE CARLO METHOD; NONEQUILIBRIUM FLOW; KINETIC ENERGY; RAREFIED GAS DYNAMICS; SIMULATION
20080031111 NASA Glenn Research Center, Cleveland, OH, United States
Heat Transfer in Conical Corner and Short Superelliptical Transition Ducts
Poinsatte, Philip; Thurman, Douglas; Hippensteele, Steven; June 2008; In English; Original contains color and black and white illustrations
Contract(s)/Grant(s): WBS 561581.02.08.03.02.02
Report No.(s): NASA/TP-2008-214944; ARL-TR-4199; E-16176; Copyright; Avail.: CASI: A03, Hardcopy
Local surface heat transfer measurements were experimentally mapped using a transient liquid-crystal heat-transfer technique on the surface of two circular-to-rectangular transition ducts. One has a transition cross section defined by conical corners (Duct 1) and the other by an elliptical equation with changing coefficients (Duct 2). Duct 1 has a length-to-diameter ratio of 0.75 and an exit plane aspect ratio of 1.5. Duct 2 has a length-to-diameter ratio of 1.0 and an exit plane aspect ratio of 2.9. Test results are reported for various inlet-diameter-based Reynolds numbers ranging from 0.45 106 to 2.39 106 and two freestream turbulence intensities of about 1 percent, which is typical of wind tunnels, and up to 16 percent, which may be more typical of real engine conditions.
Author
HEAT TRANSFER; DUCTED FLOW; LIQUID CRYSTALS; COEFFICIENTS; REYNOLDS NUMBER; ASPECT RATIO; DUCTS
20080031112 Williams International, Walled Lake, MI, United States
The General Aviation Propulsion (GAP) Program
July 2008; In English
Contract(s)/Grant(s): NCC3-514WBS 984754.02.07.03.11.02
Report No.(s): NASA/CR-2008-215266; E-16536; No Copyright; Avail.: CASI: A04, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031112
The General Aviation Propulsion (GAP) Program Turbine Engine Element focused on the development of an advanced small turbofan engine. Goals were good fuel consumption and thrust-to-weight ratio, and very low production cost. The resulting FJX-2 turbofan engine showed the potential to meet all of these goals. The development of the engine was carried through to proof of concept testing of a complete engine system. The proof of concept engine was ground tested at sea level and in altitude test chambers. A turboprop derivative was also sea-level tested.
Author
TURBOFAN ENGINES; TURBINE ENGINES; ENGINE DESIGN; GENERAL AVIATION AIRCRAFT; PROPULSION; THRUST-WEIGHT RATIO; ALTITUDE TESTS
20080031113 NASA Langley Research Center, Hampton, VA, United States
Vibroacoustic Response of Residential Housing due to Sonic Boom Exposure: A Summary of two Field Tests
Klos, Jacob; Buehrle, Ralph; Sullivan, Brenda; Gavin, Joseph; Salamone, Joseph; Haering, Edward A., jr.; Miller, Denise M.; July 28, 2008; In English; Noise-Con 2008, 28-31 Jul. 2008, Dearborn, MI, United States; Original contains color and black and white illustrations
Contract(s)/Grant(s): WBS 984754.02.07.07.18.02
Copyright; Avail.: CASI: A03, Hardcopy
Two experiments have been performed to measure the vibroacoustic response of houses exposed to sonic booms. In 2006, an old home in the base housing area of Edwards Air Force Base, built around 1960 and demolished in 2007, was instrumented with 288 transducers. During a 2007 follow-on test, a newer home in the base housing area, built in 1997, was instrumented with 112 transducers. For each experiment, accelerometers were placed on walls, windows and ceilings in bedrooms of the house to measure the vibration response of the structure. Microphones were placed outside and inside the house to measure the excitation field and resulting interior sound field. The vibroacoustic response of each house was measured for sonic boom amplitudes spanning from 2.4 to 96 Pa (0.05 to 2 lbf/sq ft). The boom amplitudes were systematically varied using a unique dive maneuver of an F/A-18 airplane. In total, the database for both houses contains vibroacoustic response data for 154 sonic booms. In addition, several tests were performed with mechanical shaker excitation of the structure to characterize the forced response of the houses. The purpose of this paper is to summarize all the data from these experiments that are available to the research community, and to compare and contrast the vibroacoustic behavior of these two dissimilar houses.
Author
ACOUSTICS; SOUND FIELDS; SONIC BOOMS; VIBRATIONAL STRESS; ACCELEROMETERS; WALLS
20080031114 NASA Langley Research Center, Hampton, VA, United States
Measured Rattle Threshold of Residential House Windows
Sizov, Natalia; Schultz, Troy; Hobbs, Christopher; Klos, Jacob; July 28, 2008; In English; Noise-Con 2008, 28-31 Jul. 2008, Dearborn, MI, United States; Original contains color and black and white illustrations
Contract(s)/Grant(s): NNL05AA04ZWBS 984754.20.07.07.18.02
No Copyright; Avail.: CASI: A02, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031114
Window rattle is a common indoor noise effect in houses exposed to low frequency noise from such sources as railroads, blast noise and sonic boom. Human perception of rattle can be negative that is a motivating factor of the current research effort to study sonic boom induced window rattle. A rattle study has been conducted on residential houses containing windows of different construction at a variety of geographic locations within the United States. Windows in these houses were excited by a portable, high-powered loudspeaker and enclosure specifically designed to be mounted on the house exterior to cover an entire window. Window vibration was measured with accelerometers placed on different window components. Reference microphones were also placed inside the house and inside of the loudspeaker box. Swept sine excitation was used to identify the vibration threshold at which the response of the structure becomes non-linear and begins to rattle. Initial results from this study are presented and discussed. Future efforts will continue to explore the rattle occurrence in windows of residential houses exposed to sonic booms.
Author
SONIC BOOMS; VIBRATION; LOW FREQUENCIES; ENCLOSURE; EXCITATION; MICROPHONES
20080031115 NASA Langley Research Center, Hampton, VA, United States
Models in the Design and Validation of Eddy Current Inspection for Cracking in the Shuttle Reaction Control System Thruster
Aldrin, John C.; July 23, 2008; In English; 35th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE), 20-25 Jul. 2008, Chicago, IL, United States; Original contains color and black and white illustrations
Contract(s)/Grant(s): WBS 377816.06.02.03.05
Copyright; Avail.: CASI: A03, Hardcopy
Two numerical methods, FEM and VIM, were used to simulate eddy current NDE for cracks in a complex thruster geometry. Model demonstrated trends observed in experimental studies. Sensitivity studies performed to determine the ideal probe orientations and frequencies for varying crack lengths. To make an accurate comparison between designs using simulation: a) Need accurate measurement models; b) Must include all critical variances in measurements. MAPOD study outlined with preliminary design results.
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EDDY CURRENTS; CRACK PROPAGATION; NONDESTRUCTIVE TESTS; THRUSTORS; SPACE SHUTTLES; NUMERICAL ANALYSIS; CRACKS; INSPECTION
20080031116 NASA Langley Research Center, Hampton, VA, United States
Experimental Evaluation of a Planning Language Suitable for Formal Verification
Butler, Rick W.; Munoz, Cesar A.; Siminiceanu, Radu I.; June 21, 2008; In English; MOCHART-2008: The Fifth International Workshop on Model Checking and Artificial Inte, 21-22 Jul. 2008, Patras, Greece; Original contains color and black and white illustrations
Contract(s)/Grant(s): NCC-1-02043WBS 015792.04.01.04
No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031116
The marriage of model checking and planning faces two seemingly diverging alternatives: the need for a planning language expressive enough to capture the complexity of real-life applications, as opposed to a language simple, yet robust enough to be amenable to exhaustive verification and validation techniques. In an attempt to reconcile these differences, we have designed an abstract plan description language, ANMLite, inspired from the Action Notation Modeling Language (ANML) [17]. We present the basic concepts of the ANMLite language as well as an automatic translator from ANMLite to the model checker SAL (Symbolic Analysis Laboratory) [7]. We discuss various aspects of specifying a plan in terms of constraints and explore the implications of choosing a robust logic behind the specification of constraints, rather than simply propose a new planning language. Additionally, we provide an initial assessment of the efficiency of model checking to search for solutions of planning problems. To this end, we design a basic test benchmark and study the scalability of the generated SAL models in terms of plan complexity.
Author
MATHEMATICAL MODELS; PROGRAM VERIFICATION (COMPUTERS); LANGUAGE PROGRAMMING; AUTONOMY
20080031117 NASA Langley Research Center, Hampton, VA, United States
Wind Tunnel Testing of Powered Lift, All-Wing STOL Model
Collins, Scott W.; Westra, Bryan W.; Lin, John C.; Jones, Gregory S.; Zeune, Cal H.; July 22, 2008; In English; 2008 International Powered Lift Conference, 22-24 Jul. 2008, London, United Kingdom; Original contains color and black and white illustrations
Contract(s)/Grant(s): WBS 561581.02.08.07.20.04
Copyright; Avail.: CASI: A03, Hardcopy
Short take-off and landing (STOL) systems can offer significant capabilities to warfighters and, for civil operators thriving on maximizing efficiencies they can improve airspace use while containing noise within airport environments. In order to provide data for next generation systems, a wind tunnel test of an all-wing cruise efficient, short take-off and landing (CE STOL) configuration was conducted in the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) 14- by 22-foot Subsonic Wind Tunnel. The test s purpose was to mature the aerodynamic aspects of an integrated powered lift system within an advanced mobility configuration capable of CE STOL. The full-span model made use of steady flap blowing and a lifting centerbody to achieve high lift coefficients. The test occurred during April through June of 2007 and included objectives for advancing the state-of-the-art of powered lift testing through gathering force and moment data, on-body pressure data, and off-body flow field measurements during automatically controlled blowing conditions. Data were obtained for variations in model configuration, angles of attack and sideslip, blowing coefficient, and height above ground. The database produced by this effort is being used to advance design techniques and computational tools for developing systems with integrated powered lift technologies.
Author
SHORT TAKEOFF AIRCRAFT; POWERED LIFT AIRCRAFT; WIND TUNNEL TESTS; AERODYNAMIC COEFFICIENTS; ANGLE OF ATTACK; SYSTEMS INTEGRATION; AIRSPACE
20080031119 NASA Langley Research Center, Hampton, VA, United States
Overview of CFD Validation Experiments for Circulation Control Applications at NASA
Jones, G. S.; Lin, J. C.; Allan, B. G.; Milholen, W. E.; Rumsey, C. L.; Swanson, R. C.; July 22, 2008; In English; 2008 International Powered Lift Conference, 22-24 Jul. 2008, London, United Kingdom; Original contains color illustrations
Contract(s)/Grant(s): WBS 561581.02.08.07.20.04
No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031119
Circulation control is a viable active flow control approach that can be used to meet the NASA Subsonic Fixed Wing project s Cruise Efficient Short Take Off and Landing goals. Currently, circulation control systems are primarily designed using empirical methods. However, large uncertainty in our ability to predict circulation control performance has led to the development of advanced CFD methods. This paper provides an overview of a systematic approach to developing CFD tools for basic and advanced circulation control applications. This four-step approach includes "Unit", "Benchmar", "Subsystem", and "Complete System" experiments. The paper emphasizes the ongoing and planned 2-D and 3-D physics orientated experiments with corresponding CFD efforts. Sample data are used to highlight the challenges involved in conducting circulation control computations and experiments.
Author
COMPUTATIONAL FLUID DYNAMICS; CONTROL SYSTEMS DESIGN; TAKEOFF; POWERED LIFT AIRCRAFT; PERFORMANCE PREDICTION; CONTROL SURFACES; AERODYNAMIC CHARACTERISTICS; FLOW DISTRIBUTION; ENGINE CONTROL
20080031122 NASA Johnson Space Center, Houston, TX, United States
Combustion Performance and Emissions Characteristics for a Well-Stirred Reactor for Low Volatility Hydrocarbon Fuels
Stouffer, Scott D.; Pawlik, Robert; Justinger, Garth; Heyne, Joshua; Zelina, Joe; Ballal, Dilip; July 08, 2007; In English; 43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, 8-11 Ju. 2007, Cincinnati, OH, United States; Original contains color illustrations
Contract(s)/Grant(s): NAS3-01135; 200-18-14U38773
Report No.(s): AIAA Paper 2007-5663; Copyright; Avail.: CASI: A03, Hardcopy
The performance and gaseous emissions were measured for a well-stirred reactor operating under lean conditions for two fuels: JP8 and a synthetic Fisher-Tropsch fuel over a range of equivalence ratios from 0.6 down to lean blowout. The lean blowout characteristics were determined in LBO experiments at loading parameter values from 0.7 to 1.4. The lean blowout characteristics were then explored under higher loading conditions by simulating higher altitude operation with the use of nitrogen to dilute the air. The results show that the two fuels have very similar combustion performance and lean blowout characteristics. Most of the differences observed in the emissions characteristics can be directly attributed to the difference in the C/H ratio of the two fuels.
Author
HYDROCARBON FUELS; JP-8 JET FUEL; SYNTHETIC FUELS; COMBUSTION EFFICIENCY; COMBUSTION STABILITY; COMBUSTION PRODUCTS; EXHAUST GASES; EXHAUST EMISSION; COMBUSTION CHAMBERS
20080031123 NASA Goddard Space Flight Center, Greenbelt, MD, United States
A New Approach to Inferences for Pancake Domes on Venus
Glaze, Lori S.; Baloga, Steve M.; Stofan, Ellen R.; March 10, 2008; In English; Lunar Planetary Science Conference, 10-14 Mar. 2008, Houston, TX, United States; Original contains black and white illustrations
Copyright; Avail.: CASI: A01, Hardcopy
Figure 1 shows a radar image and topography for flat-topped, steep-sided "pancake" domes on Venus. At least 145 such domes have been identified on Venus [I] and are thought to be volcanic in origin [2]. Based on analysis of the dome surfaces, [3] suggested that only the late stage surface fractures are preserved, indicating entrainment and annealing of fractures during emplacement, consistent with a basaltic composition. Figure 1 shows a radar image and topography for flat-topped, steep-sided "pancake" domes on Venus. At least 145 such domes have been identified on Venus [I] and are thought to be volcanic in origin [2]. Based on analysis of the dome surfaces, [3] suggested that only the late stage surface fractures are preserved, indicating entrainment and annealing of fractures during emplacement, consistent with a basaltic composition.
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RADAR IMAGERY; TOPOGRAPHY; VOLCANOES; VENUS (PLANET); BASALT
20080031138 NASA Goddard Space Flight Center, Greenbelt, MD, United States
The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations
Tao, Wei-Kuo; Li, Xiaowen; Khain, Alexander; Matsui, Toshihisa; Lang, Stephen; Simpson, Joanne; July 06, 2008; In English; International Conference on Clouds and Precipitation/ICCP 2008, 6-12 Jul. 2008, Cancun, Mexico; Original contains black and white illustrations
Copyright; Avail.: CASI: A01, Hardcopy
Aerosols and especially their effect on clouds are one of the key components of the climate system and the hydrological cycle [Ramanathan et al., 2001]. Yet, the aerosol effect on clouds remains largely unknown and the processes involved not well understood. A recent report published by the National Academy of Science states "The greatest uncertainty about the aerosol climate forcing - indeed, the largest of all the uncertainties about global climate forcing - is probably the indirect effect of aerosols on clouds [NRC, 2001]." The aerosol effect on clouds is often categorized into the traditional "first indirect (i.e., Twomey)" effect on the cloud droplet sizes for a constant liquid water path [Twomey, 1977] and the "semi-direct" effect on cloud coverage [e.g., Ackerman et al ., 2001]." Enhanced aerosol concentrations can also suppress warm rain processes by producing a narrow droplet spectrum that inhibits collision and coalescence processes [e.g., Squires and Twomey, 1961; Warner and Twomey, 1967; Warner, 1968; Rosenfeld, 19991. The aerosol effect on precipitation processes, also known as the second type of aerosol indirect effect [Albrecht, 1989], is even more complex, especially for mixed-phase convective clouds. Table 1 summarizes the key observational studies identifying the microphysical properties, cloud characteristics, thermodynamics and dynamics associated with cloud systems from high-aerosol continental environments. For example, atmospheric aerosol concentrations can influence cloud droplet size distributions, warm-rain process, cold-rain process, cloud-top height, the depth of the mixed phase region, and occurrence of lightning. In addition, high aerosol concentrations in urban environments could affect precipitation variability by providing an enhanced source of cloud condensation nuclei (CCN). Hypotheses have been developed to explain the effect of urban regions on convection and precipitation [van den Heever and Cotton, 2007 and Shepherd, 2005]. Please see Tao et al. (2007) for more detailed description on aerosol impact on precipitation. Recently, a detailed spectral-bin microphysical scheme was implemented into the Goddard Cumulus Ensemble (GCE) model. Atmospheric aerosols are also described using number density size-distribution functions. A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep tropical clouds in the west Pacific warm pool region and summertime convection over a mid-latitude continent with different concentrations of CCN: a low "clean" concentration and a high "dirty" concentration. The impact of atmospheric aerosol concentration on cloud and precipitation will be investigated.
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AEROSOLS; CLOUDS (METEOROLOGY); ATMOSPHERIC MODELS; SIMULATION; CONDENSATION NUCLEI; PRECIPITATION (METEOROLOGY)
20080031172 NASA Dryden Flight Research Center, Edwards, CA, United States
Operational Experience with Long Duration Wildfire Mapping: UAS Missions Over the Western United States
Hall, Philip; Cobleigh, Brent; Buoni, Greg; Howell, Kathleen; June 12, 2008; In English; AUVSI Unmanned Systems North America 2008, 10-12 Jun. 2008, San Diego, CA, United States; Original contains color illustrations
No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031172
The National Aeronautics and Space Administration, United States Forest Service, and National Interagency Fire Center have developed a partnership to develop and demonstrate technology to improve airborne wildfire imaging and data dissemination. In the summer of 2007, a multi-spectral infrared scanner was integrated into NASA's Ikhana Unmanned Aircraft System (UAS) (a General Atomics Predator-B) and launched on four long duration wildfire mapping demonstration missions covering eight western states. Extensive safety analysis, contingency planning, and mission coordination were key to securing an FAA certificate of authorization (COA) to operate in the national airspace. Infrared images were autonomously geo-rectified, transmitted to the ground station by satellite communications, and networked to fire incident commanders within 15 minutes of acquisition. Close coordination with air traffic control ensured a safe operation, and allowed real-time redirection around inclement weather and other minor changes to the flight plan. All objectives of the mission demonstrations were achieved. In late October, wind-driven wildfires erupted in five southern California counties. State and national emergency operations agencies requested Ikhana to help assess and manage the wildfires. Four additional missions were launched over a 5-day period, with near realtime images delivered to multiple emergency operations centers and fire incident commands managing 10 fires.
Author
FIRES; UNITED STATES; THEMATIC MAPPING; UNMANNED AIRCRAFT SYSTEMS
20080031173 NASA Langley Research Center, Hampton, VA, United States
1D-VAR Retrieval Using Superchannels
Liu, Xu; Zhou, Daniel; Larar, Allen; Smith, William L.; Schluessel, Peter; Mango, Stephen; SaintGermain, Karen; July 06, 2008; In English; 2008 IEEE IGARSS, 6-11 Jul. 2008, Boston, MA, United States
Contract(s)/Grant(s): WBS 534173.02.07.9456.01
Copyright; Avail.: CASI: A01, Hardcopy
Since modern ultra-spectral remote sensors have thousands of channels, it is difficult to include all of them in a 1D-var retrieval system. We will describe a physical inversion algorithm, which includes all available channels for the atmospheric temperature, moisture, cloud, and surface parameter retrievals. Both the forward model and the inversion algorithm compress the channel radiances into super channels. These super channels are obtained by projecting the radiance spectra onto a set of pre-calculated eigenvectors. The forward model provides both super channel properties and jacobian in EOF space directly. For ultra-spectral sensors such as Infrared Atmospheric Sounding Interferometer (IASI) and the NPOESS Airborne Sounder Testbed Interferometer (NAST), a compression ratio of more than 80 can be achieved, leading to a significant reduction in computations involved in an inversion process. Results will be shown applying the algorithm to real IASI and NAST data.
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ALGORITHMS; REMOTE SENSORS; MATHEMATICAL MODELS; ATMOSPHERIC SOUNDING
20080031174 NASA Langley Research Center, Hampton, VA, United States
Pressure and Thrust Measurements of a High-Frequency Pulsed Detonation Tube
Nguyen, N.; Cutler, A. D.; July 02, 2008; In English; 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, 20-23 Jul. 2008, Hartford, CT, United States
Contract(s)/Grant(s): NNL06AA16AWBS 526282.01.07.04.06
No Copyright; Avail.: CASI: A02, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031174
This paper describes measurements of a small-scale, high-frequency pulsed detonation tube. The device utilized a mixture of H2 fuel and air, which was injected into the device at frequencies of up to 1200 Hz. Pulsed detonations were demonstrated in an 8-inch long combustion volume, at about 600 Hz, for the quarter wave mode of resonance. The primary objective of this experiment was to measure the generated thrust. A mean value of thrust was measured up to 6.0 lb, corresponding to H2 flow based specific impulse of 2970 s. This value is comparable to measurements in H2-fueled pulsed detonation engines (PDEs). The injection and detonation frequency for this new experimental case was much higher than typical PDEs, where frequencies are usually less than 100 Hz. The compact size of the device and high frequency of detonation yields a thrust-per-unit-volume of approximately 2.0 pounds per cubic inch, and compares favorably with other experiments, which typically have thrust-per-unit-volume of order 0.01 pound per cubic inch. This much higher volumetric efficiency results in a potentially much more practical device than the typical PDE, for a wide range of potential applications, including high-speed boundary layer separation control, for example in hypersonic engine inlets, and propulsion for small aircraft and missiles.
Author
HIGH FREQUENCIES; PULSE DETONATION ENGINES; THRUST MEASUREMENT; PRESSURE MEASUREMENT
20080031175 NASA Langley Research Center, Hampton, VA, United States
An Instrument to Enable Identification of Anthropogenic CO2 Emissions Using Concurrent CO Measurements
Cook, William B.; Crawford, James H.; Diskin, Glenn S.; Gordley, Larry L.; Rubio, Manuel; Sachse, Glen W.; July 23, 2008; In English; NASA ASCENDS Workshop, 23-25 Jul. 2008, Ann Arbor, MI, United States; Original contains color illustrations
Contract(s)/Grant(s): WBS 698671.01.07.99.03
Copyright; Avail.: CASI: A01, Hardcopy
We have developed an instrument concept that will enable the measurement of CO from the top of the atmosphere to the Earth's surface with very high sensitivity and at the high spatial and temporal resolutions required by the NRC Decadal Survey mission Active Sensing of Carbon Dioxide (CO2) over Nights, Days and Seasons (ASCENDS). We are developing an innovative CO sensor that will enable the ASCENDS mission to differentiate between anthropogenic and natural sources and sinks of global carbon. The NRC Decadal Survey places particular emphasis on retrieving CO information for the planetary boundary layer. Measurement made using both the 2.3 micron and 4.7 micron channels are needed to achieve the sensitivity required in the lower atmosphere where the degree of CO - CO2 correlation is indicative of anthropogenic sources of CO2. Measurements made using only the 4.7 micron channel cannot provide sufficient sensitivity to CO in the very lowest layers of the atmosphere. The fundamental method we use is Gas Filter Correlation Radiometry (GFCR), a highly successful technique used in other airborne and space-based missions for detecting trace species in the Earth's atmosphere. Our version of GFCR overcomes many of the limitations encountered by prior and existing instruments, allowing us to measure weak signals from small targets very quickly and with extremely high specificity by employing a new dual beam radiometer concept using a focal plane array. Our design will provide a means to make the desired CO measurements for the ASCENDS mission. A simple change in gas filter cell contents would allow the same hardware to measure CH4 with high precision under the nominal ASCENDS mission spatial and temporal constraints. All critical components in the sensor design are mature, many subsystems tested, and the system has been extensively modeled, bringing it to a present Technology Readiness Level (TRL) of 3 (though some individual components are at TRLs 6-9). We are presently developing critical components for the new spectrometer and advancing our understanding of the measurement requirements for both CO and CH4. This new GFCR technique/sensor will enable measurements of trace gases with high sensitivity while maintaining the inherent robustness and simplicity of the more traditional radiometer hardware. Initial estimates of cost/risk of a spacebased 2-channel GFCR indicate that our design is extremely cost effective and will fit within existing ASCENDS mission budget constraints as determined by the NRC Decadal Survey and a NASA-sponsored mission study.
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CARBON DIOXIDE; CARBON MONOXIDE; ATMOSPHERIC COMPOSITION; EARTH SURFACE; DETECTION; EMISSION; RADIOMETERS
20080031176 NASA Glenn Research Center, Cleveland, OH, United States
Aircraft Engine On-Line Diagnostics Through Dual-Channel Sensor Measurements: Development of an Enhanced System
Kobayashi, Takahisa; Simon, Donald L.; June 2008; In English; ASME Turbo Expo 2008, 9-13 Jun. 2008, Berlin, Germany; Original contains color illustrations
Contract(s)/Grant(s): WBS 645856.02.07.03.03.01
Report No.(s): NASA/TM-2008-215229; GT2008-50346; E-16516; No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031176
In this paper, an enhanced on-line diagnostic system which utilizes dual-channel sensor measurements is developed for the aircraft engine application. The enhanced system is composed of a nonlinear on-board engine model (NOBEM), the hybrid Kalman filter (HKF) algorithm, and fault detection and isolation (FDI) logic. The NOBEM provides the analytical third channel against which the dual-channel measurements are compared. The NOBEM is further utilized as part of the HKF algorithm which estimates measured engine parameters. Engine parameters obtained from the dual-channel measurements, the NOBEM, and the HKF are compared against each other. When the discrepancy among the signals exceeds a tolerance level, the FDI logic determines the cause of discrepancy. Through this approach, the enhanced system achieves the following objectives: 1) anomaly detection, 2) component fault detection, and 3) sensor fault detection and isolation. The performance of the enhanced system is evaluated in a simulation environment using faults in sensors and components, and it is compared to an existing baseline system.
Author
DIAGNOSIS; ON-LINE SYSTEMS; AIRCRAFT ENGINES; SENSORS; SYSTEMS HEALTH MONITORING; CHANNELS (DATA TRANSMISSION)
20080031178 NASA Langley Research Center, Hampton, VA, United States
Unified Application Vapor Screen Flow Visualization and Pressure Sensitive Paint Measurement Techniques to Vortex- and Shock Wave-Dominated Flow Fields
Erickson, Gary E.; July 2008; In English; FLUVISU12 - 12th French Congress on Visualization in Fluid Mechanics, 1-4 Jul. 2008, Nice, France; Original contains color and black and white illustrations
Report No.(s): ISFV13 Paper No. 122; No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031178
Laser vapor screen (LVS) flow visualization and pressure sensitive paint (PSP) techniques were applied in a unified approach to wind tunnel testing of slender wing and missile configurations dominated by vortex flows and shock waves at subsonic, transonic, and supersonic speeds. The off-surface cross-flow patterns using the LVS technique were combined with global PSP surface static pressure mappings to characterize the leading-edge vortices and shock waves that coexist and interact at high angles of attack (alpha). The synthesis of LVS and PSP techniques was also effective in identifying the significant effects of passive surface porosity and the presence of vertical tail surfaces on the flow topologies. An overview is given of LVS and PSP applications in selected experiments on small-scale models of generic slender wing and missile configurations in the NASA Langley Research Center (NASA LaRC) Unitary Plan Wind Tunnel (UPWT) and 8-Foot Transonic Pressure Tunnel (8-Foot TPT).
Author
SCALE MODELS; SHOCK WAVES; TRANSONIC WIND TUNNELS; VAPORS; VORTICES; WIND TUNNEL TESTS; PRESSURE SENSITIVE PAINTS; FLOW VISUALIZATION
20080031179 George Washington Univ., Newport News, VA, United States; NASA Langley Research Center, Hampton, VA, United States
An Experimental and Numerical Study of a Supersonic Burner for CFD Model Development
Magnotti, G.; Cutler, A. D.; July 20, 2008; In English; 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 20-23 Jul. 2008, Hartford, CT, United States; Original contains color and black and white illustrations
Contract(s)/Grant(s): WBS 732759.07.06
Copyright; Avail.: CASI: A03, Hardcopy
A laboratory scale supersonic burner has been developed for validation of computational fluid dynamics models. Detailed numerical simulations were performed for the flow inside the combustor, and coupled with finite element thermal analysis to obtain more accurate outflow conditions. A database of nozzle exit profiles for a wide range of conditions of interest was generated to be used as boundary conditions for simulation of the external jet, or for validation of non-intrusive measurement techniques. A set of experiments was performed to validate the numerical results. In particular, temperature measurements obtained by using an infrared camera show that the computed heat transfer was larger than the measured value. Relaminarization in the convergent part of the nozzle was found to be responsible for this discrepancy, and further numerical simulations sustained this conclusion.
Author
COMPUTATIONAL FLUID DYNAMICS; BURNERS; SUPERSONIC FLOW; WIND TUNNEL TESTS; MATHEMATICAL MODELS; NUMERICAL ANALYSIS
Additions to the NASA Aeronautics and Space Database as of 08/27/2008
20080031272 NASA Goddard Space Flight Center, Greenbelt, MD, United States
RS Ophiuchi in Quiescence: Why Is It X-ray Faint?
Mukai, Koji; [2007]; In English; Original contains black and white illustrations
Contract(s)/Grant(s): NNG06EO90A
No Copyright; Avail.: CASI: A01, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031272
The short interval between successive outbursts of RS Oph strongly suggests that it has a high mass white dwarf accreting at a high rate. This, in turn, suggests the possibility of prominent X-ray emission from RS Oph in quiescence. However, archival quiescent X-ray observations of RS Oph show it to be a modest soft X-ray source but not a strong 2-10 keV X-ray source. In this aspect, RS Oph differs markedly from T CrB. We speculate on the possible mechanisms that could significantly suppress the 2-10 keV X-ray emission in RS Oph.
Author
OPHIUCHI CLOUDS; ASTROPHYSICS; ROSAT MISSION; SPECTRUM ANALYSIS; X RAY ASTRONOMY
20080031343 NASA Goddard Space Flight Center, Greenbelt, MD, United States
Hemispheric and Topographic Asymmetry of Magnetospheric Particle Irradiation for Icy Moon Surfaces
Cooper, John F.; Sturner, S. J.; August 13, 2007; In English; Ices, Oceans and Fire: Satellites of the Outer Solar System Workshop, 13-15 Aug. 2007, Boulder, Co, United States
No Copyright; Avail.: CASI: A01, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031343
All surfaces of icy moons without significant atmospheres, i.e. all except Titan in the giant planet systems, are irradiated by hot plasma and more energetic charged particles from the local magnetospheric environments. This irradiation can significantly impact the chemical composition, albedo, and detectable presence of signs of life on the sensible surfaces, while also limiting lifetimes and science operations of orbital spacecraft for extreme radiation environments as at Europa. Planning of surface remote sensing and lander operations, and interpretation of remote sensing and in-situ measurements, should include consideration of natural shielding afforded by the body of the moon, by any intrinsic or induced magnetic fields as at Ganyrnede, and by topographic structures.
Author
IRRADIATION; ASYMMETRY; TOPOGRAPHY; CHEMICAL COMPOSITION; MAGNETIC FIELDS; TITAN; REMOTE SENSING; ENERGETIC PARTICLES
20080031344 NASA Goddard Space Flight Center, Greenbelt, MD, United States
Jurassic Diabase from Leeseburg, VA: A Proposed Lunar Simulant
Taylor, Patrick T.; Lowman, P. D.; Nagihara, Seiichi; Milam, M. B.; Nakamura, Yosio; July 20, 2008; In English; NASA Lunar Science Institute Meeting, 20-23 Jul. 2008, Moffett Field, CA, United States; Original contains black and white illustrations
No Copyright; Avail.: CASI: A01, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031344
A study of future lunar seismology and heat flow is being carried out as part of the NASA Lunar Sortie Science Program. This study will include new lunar drilling techniques, using a regolith simulant, for emplacement of instruments. Previous lunar simulants, such as JSC-1 and MLS-1, were not available when the study began, so a local simulant source was required. Diabase from a quarry at Leeseburg, Virginia, was obtained from the Luck Stone Corporation. We report here initial results of a petrographic examination of this rock, GSC-1 henceforth.
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SEISMOLOGY; LUNAR GEOLOGY; PETROGRAPHY; MINERALOGY
20080031346 NASA Goddard Space Flight Center, Greenbelt, MD, United States
Thermal Vacuum Testing of a Multi-Evaporator Miniature Loop Heat Pipe
Ku, Jentung; Ottenstein, Laura; Nagano, Hosei; May 13, 2008; In English; 2008 International Two-Phase Thermal Control Technology Workshop, 13-15 May 2008, Noordwijk, Netherlands; Original contains black and white illustrations
Copyright; Avail.: CASI: A03, Hardcopy
Under NASA's New Millennium Program Space Technology 8 Project, four experiments are being developed for future small system applications requiring low mass, low power, and compactness. GSFC is responsible for developing the Thermal Loop experiment, which is an advanced thermal control system consisting of a miniature loop heat pipe (MLHP) with multiple evaporators and condensers. The objective is to validate the operation of an MLHP, including reliable start-ups, steady operation, heat load sharing, and tight temperature control over the range of 273K to 308K. An MLHP Breadboard has been built and tested for 1200 hours under the laboratory environment and 500 hours in a thermal vacuum chamber. Results of the TV tests are presented here.
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HEAT PIPES; EVAPORATORS; AEROSPACE ENGINEERING; TEMPERATURE CONTROL; TECHNOLOGICAL FORECASTING; MINIATURIZATION
20080031349 NASA Goddard Space Flight Center, Greenbelt, MD, United States
Framework Based Guidance Navigation and Control Flight Software Development
McComas, David; November 05, 2007; In English; Flight Software Workshop 2007 (FSW-07), 5-6 Nov. 2007, Laurel, MD, United States; Original contains black and white illustrations
No Copyright; Avail.: CASI: A03, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031349
This viewgraph presentation describes NASA's guidance navigation and control flight software development background. The contents include: 1) NASA/Goddard Guidance Navigation and Control (GN&C) Flight Software (FSW) Development Background; 2) GN&C FSW Development Improvement Concepts; and 3) GN&C FSW Application Framework.
CASI
SOFTWARE ENGINEERING; NAVIGATION; SPACE FLIGHT; GUIDANCE (MOTION); ARCHITECTURE (COMPUTERS); APPLICATIONS PROGRAMS (COMPUTERS)
20080031354 NASA Goddard Space Flight Center, Greenbelt, MD, United States
Reliability Effects of Surge Current Testing of Solid Tantalum Capacitors
Teverovsky, Alexander; December 2007; In English; Original contains black and white illustrations
No Copyright; Avail.: CASI: A04, Hardcopy
Avail Online: http://hdl.handle.net/2060/20080031354
Solid tantalum capacitors are widely used in space applications to filter low-frequency ripple currents in power supply circuits and stabilize DC voltages in the system. Tantalum capacitors manufactured per military specifications (MIL-PRF-55365) are established reliability components and have less than 0.001% of failures per 1000 hours (the failure rate is less than 10 FIT) for grades D or S, thus positioning these parts among electronic components with the highest reliability characteristics. Still, failures of tantalum capacitors do happen and when it occurs it might have catastrophic consequences for the system. This is due to a short-circuit failure mode, which might be damaging to a power supply, and also to the capability of tantalum capacitors with manganese cathodes to self-ignite when a failure occurs in low-impedance applications. During such a failure, a substantial amount of energy is released by exothermic reaction of the tantalum pellet with oxygen generated by the overheated manganese oxide cathode, resulting not only in destruction of the part, but also in damage of the board and surrounding components. A specific feature of tantalum capacitors, compared to ceramic parts, is a relatively large value of capacitance, which in contemporary low-size chip capacitors reaches dozens and hundreds of microfarads. This might result in so-called surge current or turn-on failures in the parts when the board is first powered up. Such a failure, which is considered as the most prev | |
