Spectral Sciences Incorporated

About: Spectral Sciences Incorporated is a company organization based out in Burlington, Massachusetts, United States. It is known for research contribution in the topics: Hyperspectral imaging & Radiance. The organization has 114 authors who have published 342 publications receiving 10875 citations.

Numerical modeling of transient plume impingement during high altitude rocket staging

Abstract: The direct simulation Monte Carlo (DSMC) method is used to model a transient stage separation of a generic sounding rocket at 100 km. Lower stage movement is included, and the o w and surface properties are simulated over the rst second after thruster ignition. Both liquid and solid propellant thrusters are examined with a thrust of 25 kN and 34 kN, respectively. Four dieren t simulation scenarios are considered that allow analysis of the impact of the stage motion, explcitly including unsteady o w eects. Unsteady o w eects are small enough that quasi-steady state modeling appears to be adequate for this general staging scenario. The inuence of DSMC statistical uctuations on the stage trajectory is insignican t compared to the total contribution of the plume force. We also examine the radiation environment, including the plume-atmosphere shock and plume-lower stage impingement.

Remote optical interrogation of vibrations in materials inspection applications

Abstract: Vibration waveforms in materials appear in video as a minuscule fluctuation in the light scattered into the camera By inferring from processed video how vibrational energy propagates through an article to be inspected, we may detect local material anomalies We report progress in developing measurement protocols and technologies to perform standoff nondestructive inspection of materials for defects using video image processing In particular we show promising results from a protocol that conforms to relatively inexpensive hardware

Clear sky blinks

Abstract: Ice blinks and water skies are brightness variations on the undersides of overcasts that allow ground-based observers to judge the nature of distant surfaces such as water (dark) or ice (bright). The clear sky should also scatter light from distant surfaces that might be visually detectable. We demonstrate that clear sky blinks do occur, can be visually discerned, and can be successfully photographed. We also model them theoretically using Monte Carlo simulations. The presence of atmospheric aerosols significantly enhances clear sky blinks.

The Last Movement, Part 2: Judgment in Action, Musical Development, and Some Continuing Enigmas

Abstract: Chapter 10 explores Mahler’s musical portrayal of the Last Judgment. It begins with hair-raising percussion crescendos meant to depict the raising of the dead. A march emblemizes the twin sides of judgment: damnation and the hope of those who petition for mercy. Damnation is captured in the Dies irae, hope in the sound of hymns. The sensual English horn theme returns. This time, an offstage band combines military fanfares (evocative of the march) with the sensual music, leading to increased bewilderment about the meaning of the latter. Whatever it means, its frequent juxtaposition to the music of judgment (either serially or as is so this time, simultaneously) seems to be taking on the accoutrements of a potent dramatic conflict. This section of the finale concludes with a powerful example of musical antithesis: a return of the orchestral scream, followed by an expansive rendition of the placid immortality motive from Siegfried.

MODTRAN5 analysis of clear-sky, co-located space- and ground-based infrared atmospheric measurements: AERI, AIRS, CERES, MODIS

Abstract: A set of 26 clear-sky, co-located, infrared data from NASA's space-based, downward looking Atmospheric Infrared Sounder (AIRS)1 and its Clouds and the Earth's Radiant Energy System (CERES)2 have been paired with the DOE's Southern Great Plains (SGP)3 ground-based, upward looking Atmospheric Emitted Radiance Interferometer (AERI)4. These data sets have then been simulated using the MODTRAN®55 (MOD5) radiative transfer code with standard auxiliary 'truth' data as input. Of particular interest is the impact, if any, of the large Ground Sampling Distance (GSD) of AIRS and CERES (minimum radii of approximately 13 and 26 km, respectively) vs. the soda-straw up-looking mode of AERI. The smaller Moderate Resolution Imaging Spectroradiometer (MODIS)6 GSD (<1 km) provides estimated distributions of land-type and albedo within the larger footprints. The SGP's coincident vertical profile sondes and Aeronet7 retrievals, along with other satellite data [Ozone Monitoring Instrument (OMI)8] constrain the surface type, column ozone and aerosol optical depth that existed during the measurement events. Initial MOD5 calculations, using these ancillary data as input, have replicated the AERI and AIRS measurements to within an average difference of ~1% over their entire spectral range. Using MODIS visible albedo9 retrievals to extend the albedo into the long wave (LW) only slightly improved the statistical comparison between the CERES and MOD5 broadband LW radiances agreement, from 3% to ~1.5%, while increasing the variance. While these results are not sufficient for specific instrument inversion algorithms, they suggest some confidence in the generic use of MODTRAN®5 to help integrate and spectrally extend assorted data sets for sensitivity studies of Climate Change, where the estimated required sensitivity is <1%.