1,039 research outputs found

    Final shuttle-derived atmospheric database: Development and results from thirty-two flights

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    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

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    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

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    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

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    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

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    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

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    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

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    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

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    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 JPCJ^{PC} 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 π0\pi^0 or η\eta. A first important result is the observation of a significant JPCJ^{PC} spin exotic signal consistent with the disputed π1(1600)\pi_1(1600) 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

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    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

    2,2-Diphenyl­acetamide

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    In the title compound, C14H13NO, which has two mol­ecules in the asymmetric unit, the dihedral angles between the mean planes of the benzene rings are 84.6 (7) and 85.0 (6)°. N—H⋯O hydrogen bonds [forming R 2 2(8) ring motifs] and C—H⋯O hydrogen bonds dominate the crystal packing, forming zigzag chains parallel to the a axis. In addition, weak inter­molecular C—H⋯π inter­actions are observed
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