1,040 research outputs found
Final shuttle-derived atmospheric database: Development and results from thirty-two flights
The final Shuttle-derived atmospheric data base is presented. The relational data base is comprised of data from 32 Space Transportation System (STS) descent flights, to include available meteorology data taken in support of each flight. For the most part, the available data are restricted to the middle atmosphere. In situ accelerations, sensed by the tri-redundant Inertial Measurement Unit (IMU) to an accuracy better than 1 mg, are combined with post-flight Best Estimate Trajectory (BET) information and predicted, flight-substantiated Orbiter aerodynamics to provide determinations up to altitudes of 95 km. In some instances, alternate accelerometry data with micro-g resolution were utilized to extend the data base well into the thermosphere. Though somewhat limited, the ensemble of flights permit a reasonable sampling of monthly, seasonal, and latitudinal variations which can be utilized for atmospheric science investigations and model evaluations and upgrades as appropriate. More significantly, the unparallel vertical resolution in the Shuttle-derived results indicate density shears normally associated with internal gravity waves or local atmospheric instabilities. Consequently, these atmospheres can also be used as stress-atmospheres for Guidance, Navigation and Control (GN and C) system development and analysis as part of any advanced space vehicle design activities
Thermal analysis of the vertical bridgman semiconductor crystal growth technique
The quality of semiconductor crystals grown by the vertical Bridgman technique is strongly influenced by the axial and radial variations of temperature within the charge. The relationship between the thermal parameters of the vertical Bridgman system and the thermal behavior of the charge are examined. Thermal models are developed which are capable of producing results expressable in analytical form and which can be used without recourse to extensive computer work for the preliminary thermal design of vertical Bridgman crystal growth systems. These models include the effects of thermal coupling between the furnace and the charge, charge translation rate, charge diameter, thickness and thermal conductivity of the confining crucible, thermal conductivity change and liberation of latent heat at the growth interface, and infinite charge length. The hot and cold zone regions, considered to be at spatially uniform temperatures, are separated by a gradient control region which provides added thermal design flexibility for controlling the temperature variations near the growth interface
Final STS-35 Columbia descent BET products and results for LaRC OEX investigations
Final STS-35 'Columbia' descent Best Estimate Trajectory (BET) products have been developed for Langley Research Center (LaRC) Orbiter Experiments (OEX) investigations. Included are the reconstructed inertial trajectory profile; the Extended BET, which combines the inertial data and, in this instance, the National Weather Service atmospheric information obtained via Johnson Space Center; and the Aerodynamic BET. The inertial BET utilized Inertial Measurement Unit 1 (IMU1) dynamic measurements for deterministic propagation during the ENTREE estimation process. The final estimate was based on the considerable ground based C-band tracking coverage available as well as Tracking Data and Relay Satellite System (TDRSS) Doppler data, a unique use of the latter for endo-atmospheric flight determinations. The actual estimate required simultaneous solutions for the spacecraft position and velocity, spacecraft attitude, and six IMU parameters - three gyro biases and three accelerometer scale factor correction terms. The anchor epoch for this analysis was 19,200 Greenwich Mean Time (GMT) seconds which corresponds to an initial Shuttle altitude of approximately 513 kft. The atmospheric data incorporated were evaluated based on Shuttle derived considerations as well as comparisons with other models. The AEROBET was developed based on the Extended BET, the measured spacecraft configuration information, final mass properties, and the final Orbiter preoperation databook. The latter was updated based on aerodynamic consensus incrementals derived by the latest published FAD. The rectified predictions were compared versus the flight computed values and the resultant differences were correlated versus ensemble results for twenty-two previous STS entry flights
Spectrophotometric Study of Acid-Base Equilibria in Non-Aqueous Solvents
The equilibrium constants for the reaction of 2,6-dichloro-4-
-nitrophenol, 2,6-dinitrophenol, 2,5-dinitrophenol and 2,4-dinitrophenol
with some aliphatic amines of different structures have been
determined spectrophotometrically in chlorobenzene, ethyl acetate
and carbon tetrachloride as solvents. The data show that such
reactions in inert solvents lead essentially to ion-pairs of the type
BH+ ... A- where, HA and B represent the phenol and ·amine
molecule, respectively. This conclusions was found to be in agreement
with that obtained by other workers. In chlorobenzene as a
solvent, the basic strengths fall in the order mono < di- < tri-n-
. -butyl amine, while in ethyl acetate the order of basic strengths
becomes: mono-> di-> tri-n-butyl amine. These results are discussed
from the point of view of solvation as an important role in
the determination of the relative strengths of butylamines, as well
as the extent to which dinitrophenols are affected by chelation
between the phenolic OH and ortho-nitro group. However, in chlorobenzene
and ethyl acetate as solvents, the relative basic strengths
of pyridine and aniline derivatives remain independent of the
solvent when bromophenol blue is used as a reference acid. The
of KBH+A- values for aniline derivatives proved to be more suitable
for judging the effect of the substituent than the basic strength in
aqueous solution
Opipramolium fumarate
In the crystal structure of the title salt {systematic name: 4-[3-(5H-dibenz[b,f]azepin-5-yl)propyl]-1-(2-hydroxyethyl)piperazin-1-ium (2Z)-3-carboxyprop-2-enoate}, C23H30N3O+·C4H3O4
−, the piperazine group in the opipramol cation is protonated at only one of the N atoms. In the cation, the dihedral angle between the two benzene rings is 53.5 (6)°. An extensive array of intermolecular O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds and weak intermolecular N—H⋯O, C—H⋯O and C—H⋯π interactions dominate the crystal packing
9-[3-(Dimethylamino)propyl]-2-trifluoromethyl-9H-thioxanthen-9-ol
In the title compound, C19H20F3NOS, the dihedral angle between the mean planes of the two benzene rings attached to the thioxanthene ring is 41.8 (7)°; the latter has a slightly distorted boat conformation. The F atoms are disordered over three sets of sites [occupancy ratio = 0.564 (10):0.287 (10):0.148 (5)] and the methyl groups are disordered over two sets of sites [occupancy ratio = 0.72 (4):0.28 (4)]. The crystal packing is stabilized by O—H⋯N and C—H⋯S hydrogen bonds and weak C—H⋯Cg interactions
2,2-Diphenyl-4-(piperidin-1-yl)butanamide
In the title compound, C21H26N2O, the dihedral angle between the mean planes of the two benzene rings is 81.1 (9)°. The piperidine ring is in a chair conformation. The crystal packing is stabilized by N—H⋯N and N—H⋯O hydrogen bonds and weak intermolecular C—H⋯O interactions
Meson spectroscopy with COMPASS
The COMPASS fixed-target experiment at CERN SPS is dedicated to the study of
hadron structure and dynamics. In the physics programme using hadron beams, the
focus is on the detection of new states, in particular the search for
exotic states and glueballs. After a short pilot run in 2004 (190 GeV/c
negative pion beam, lead target), we started our hadron spectroscopy programme
in 2008 by collecting an unprecedented statistics with a negative hadron beam
(190 GeV/c) on a liquid hydrogen target. A similar amount of data with positive
hadron beam (190 GeV/c) has been taken in 2009, as well as some additional data
with negative beam on nuclear targets. The spectrometer features a large
angular acceptance and high momentum resolution and also good coverage by
electromagnetic calorimetry, crucial for the detection of final states
involving or . A first important result is the observation of a
significant spin exotic signal consistent with the disputed
in the pilot run data. This result was recently published. We
present an overview of the status of various ongoing analyses on the 2008/09
data.Comment: 6 pages, 6 figures, to appear in the proceedings of the International
Nuclear Physics Conference 2010, Vancouver, Canada, 04-09 Jul 201
Methyl 2-(4-hydroxybenzoyl)benzoate
In the title compound, C15H12O4, the dihedral angle between the benzene rings is 64.0 (6)°. In the crystal, molecules are linked by O—H⋯O hydrogen bonds, forming C(8) chains propagating in [10] and the packing is reinforced by weak C—H⋯O interactions
4-Phenylsulfonyl-2-(p-tolylsulfonyl)-1H,8H-pyrrolo[2,3-b]indole
The title compound, C23H18N2O4S2, contains a pyrrolo group fused onto the plane of an indole ring with phenylsulfonyl and p-toluenesulfonyl groups bonded to the indole and pyrrolo rings. The angles between the mean planes of the pyrrolo-indole ring and the phenylsulfonyl and p-toluenesulfonyl rings are 73.7 (6) and 80.6 (0)°, respectively. The dihedral angle between the mean planes of the two benzene rings is 78.7 (4)°. In the crystal, both classical N—H⋯O and non-classical C—H⋯O intermolecular hydrogen-bonding interactions are observed, as well as weak π–π interactions [centroid–centroid distances = 3.6258 (8) and 3.9298 (8) Å], which contribute to the stability of the packing
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