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Comparison of integrated scattering cross sections of 3/2 states in Mg-25/d, alpha/Na-23 and Al-23/d, alpha/Mg-25 reactions
This work is part of the overall advanced main combustion chamber (AMCC) casting characterization program of the Materials and Processes Laboratory of the Marshall Space Flight Center. The influence of hydrogen on the tensile properties and ductility behavior of NASA-23 alloy were analyzed. NASA-23 and other referenced alloys in cast and hipped conditions were solution treated and aged under selected conditions and characterized using optical metallography, scanning electron microscopy, and electron microprobe analysis techniques. The yield strength of NASA-23 is not affected much by hydrogen under tensile tests carried at 5000 psig conditions; however, the ultimate strength and ductility properties are degraded. This implies that the physical mechanisms operating would be related to the plastic deformation process. The fracture surfaces characteristics of NASA-23 specimens tensile tested in hydrogen, helium, and air were also analyzed. These revealed surface cracks around specimen periphery with the fracture surface showing a combination of intergranular and transgranular modes of fracture. It is seen that the specimens charged in hydrogen seem to favor a more brittle fracture mode in comparison to air and helium charged specimens. The AMCC casting characterization program is to be analyzed for their hydrogen behavior. As a result of this program, the basic microstructural factors and fracture characteristics in some cases were analyzed.
Hydrogen-resistant alloy NASA-23 was developed specifically as a structural alloy for application in liquid propulsion systems that use hydrogen fuel. NASA-23 was designed to be similar to Alloy 718 in strength, ductility, and corrosion resistance, but with superior resistance to hydrogen environment embrittlement. The alloy is readily processed; it can be both hot and cold worked and is castable and weldable. A material property data base is being generated for both cast and wrought NASA-23. This paper will present the status of alloy development and discuss potential applications in propulsion systems.
Measurement results are presented for actual utilization of the short wave frequency band, obtained by continuous registration of the number of radio stations in the 16-23 MHz band over an annual cycle (1965). It is shown that there is a relation between the number of radio stations and the variations of MUF-F2. During years of minimum solar activity and at night, segments free of radio stations operating by normal reflection, can be selected in the 18-23-MHz band for ionospheric-scattering links.
The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-23 (Terrestrial Ecology) team collected hemispherical photographs in support of its efforts to characterize and interpret information on estimates of canopy architecture and radiative transfer properties for most BOREAS study sites. Various Old Aspen (OA), Old Black Spruce (OBS), Old Jack Pine (OJP), Young Jack Pine (YJP), and Young Aspen (YA) sites in the boreal forest were measured from May to August 1994. The hemispherical photographs were used to derive values of leaf area index (LAI), leaf angle, gap fraction, and clumping index. This documentation describes these derived values. The derived data are stored in tabular ASCII files. The hemispherical photographs are stored in the original set of 42 CD-ROMs that were supplied by TE-23. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).
NASA-23 alloy has been designed to fulfil NASA's unique need for a high strength, oxidation-and corrosion resistant alloy that is compatible with a high-pressure hydrogen environment. This alloy is a precipitation hardened iron-nickel base alloy with excellent strength and ductility art gaseous hydrogen (GH2), comparable to those of other alloys in its class, Inconel 718 and IN-903. NASA-23 has been designed with a sufficient amount of chromium to provide good corrosion/oxidation resistance. For hydrogen resistance, the alloy maintains a (Ni + Co)/Fe ratio close to 1.26, the same as that of Incoloy 903. Hardening constituents, Nb, Ti, and Al, are optimized for strength and ductility both in air and GH2 atmospheres.
We examine the spectral variability of the Seyfert 1.9 galaxy MCG-5-23-16 using RXTE and BeppoSAX observations spanning 2 years from April 1996 to April 1998. During the first year the X-ray source brightens by a factor of approximately 25% on timescales of days to months. During this time, the reprocessed continuum emission seen with RXTE does not respond measurably to the continuum increase. However, by the end of the second year during the BeppoSAX epoch the X-ray source has faded again. This time, the reprocessed emission has also faded, indicating that the reprocessed flux has responded to the continuum. If these effects are caused by time delays due to the distance between the X-ray source and the reprocessing region, we derive a light crossing time of between approximately 1 light day and approximately 1.5 light years. This corresponds to a distance of 0.001 pc to 0.55 pc, which implies that the reprocessed emission originates between 3 x 10(exp 15) cm and 1.6 x 10(exp l8) cm from the X-ray source. In other words, the reprocessing in MCG-5-23-16 is not dominated by the inner regions of a standard accretion disk.
We present the results of the simultaneous deep XMM-Newton and Chandra observations of the bright Seyfert 1.9 galaxy MCG-5-23-16, which is thought to have one of the best known examples of a relativistically broadened iron Kalpha line. We detected a narrow sporadic absorption line at 7.7 keV which appears to be variable on a time-scale of 20 ksec. If associated with FeXXVI this absorption is indicative of a possible variable high ionization, high velocity outflow. The time averaged spectral analysis shows that the iron K-shell complex is best modeled with an unresolved narrow emission component (FWHM less than 5000 kilometers per second, EW approx. 60 eV) plus a broad component. This latter component has FWHM approx. 44000 kilometers per second, an EW approx. 50 eV and its profile is well described with an emission line originating from the accretion disk viewed with an inclination angle approx. 40 deg. and with the emission arising from within a few tens of gravitational radii of the central black hole. The time-resolved spectral analysis of the XMM-Newton EPIC-pn spectrum shows that both the narrow and broad components of the Fe K emission line appear to be constant within the errors. The analysis of the XMM-Newton/RGS spectrum reveals that the soft X-ray emission of MCG-5-23-16 is likely dominated by several emission lines superimposed on an unabsorbed scattered power-law continuum. The lack of strong Fe L shell emission together with the detection of a strong forbidden line in the O VII triplet supports a scenario where the soft X ray emission lines are produced in a plasma photoionized by the nuclear emission.
MCG-5-23-16 is one of the first active galactic nuclei (AGNs) where relativistic reverberation in the iron K line originating in the vicinity of the supermassive black hole was found, based on a short XMM-Newton observation. In this work, we present the results from long X-ray observations using Suzaku, XMM-Newton, and NuSTAR designed to map the emission region using X-ray reverberation. A relativistic iron line is detected in the lag spectra on three different timescales, allowing the emission from different regions around the black hole to be separated. Using NuSTAR coverage of energies above 10 keV reveals a lag between these energies and the primary continuum, which is detected for the first time in an AGN. This lag is a result of the Compton reflection hump responding to changes in the primary source in a manner similar to the response of the relativistic iron K line.
MCG-5-23-16 was targeted in early 2015 with a half mega-second observing campaign using NuSTAR. Here we present the spectral analysis of these data sets along with an earlier observation and study the relativistic reflection and the primary coronal source. The data show strong reflection features in the form of both narrow and broad iron lines plus a Compton reflection hump. A cutoff energy is significantly detected in all exposures. The shape of the reflection spectrum does not change in the two years spanned by the observations, suggesting a stable geometry. A strong positive correlation is found between the cutoff energy and both the hard X-ray flux and spectral index. The measurements imply that the coronal plasma is not at the runaway electron-positron pair limit, and instead contains mostly electrons. The observed variability in the coronal properties is driven by a variable optical depth. A constant heating-to-cooling ratio is measured, implying that there is a feedback mechanism in which a significant fraction of the photons cooling the corona are due to reprocessed hard X-rays.
Catalog of satellite observations, c-23
Lunar occultation and identification of radio source MSH 21-23
Radio source MSH 21-23 observation during lunar occultation, using parabolic antenna and switched- type gain modulated receiver
Red shift and absorption line of PKS 0237-23
The Na-23 nuclear quadrupole coupling constant in Rochelle salt is found to have a linear dependence on temperature which extends through both the higher- and lower-temperature nonferroelectric phases. This result necessitates a reinterpretation of some earlier data, but is in perfect agreement with the recent calculations of Zeks, Shulka, and Blinc.
The ratio I(L-alpha)/I(H-alpha) has been measured to be 1.7 plus or minus 0.6 in the quasar PKS 0237-23. The measured ratio is similar to that measured in 3C 273 by Davidsen et al. and to that inferred by Baldwin from a study of a large number of quasars; it is a factor of 5 to 14 smaller than expected from recombination theory. If the L-alpha radiation is resonantly scattered and there are modest amounts of dust within the ionized region, the measured ratio may be interpreted in terms of recombination theory, with L-alpha being depleted by absorption by the dust.
Direct CCD imaging and long-slit Vidicon spectroscopy have been used to map the emission-line ratios, profiles, and velocity fields over the extended narrow-line regions in three nearby Seyfert galaxies, NGC 2110, NGC 5506, and MCG -5-23-16. The gas in the letter is spatially unresolved. Similarities between the other two nebulae include the excitation mechanism (photoionization by a central nonthermal source) and the overall profiles of the very broad emission lines close to the nucleus. The nebulae are, however, quite different in their global kinematic behavior. In NGC 2110, the gas appears to lie in a disk or flattened spheroid and to be in ordered rotation, with a classical rotation curve, about an axis parallel to the minor axis of the stellar isophotes. The velocity field of NGC 5506 is quite irregular, but a component of rotation in the plane of the galaxy seems to exist.
The 3-m NASA Infrared Telescope Facility was used to observe the disks of Uranus and Neptune between May 30 and June 1, 1985 in the 7-14 and 17-23 micron spectral regions. Maximum stratospheric mixing ratios of 9 x 10 to the -9th for C2H2, and of 2 x 10 to the -8th for C2H6, are found for Uranus, and the spectrum is otherwise smooth, consistent with the opacity provided by H2 collision-induced absorption and spectrally continuous stratospheric emission. Strong emission features of CH4 and C2H6 are found in the short-wavelength spectrum of Neptune, and the spectrum near 13.5 microns is consistent with C2H2 emission in local saturation equilibrium with a maximum mixing ratio of 9 x 10 to the -7th.