1,386 research outputs found
Some Structural and Thermal Characteristics of Snow Shelters
Reports investigations of dome-shaped shelters constructed in Alaska during winter 1955-56, some of loose, unconsolidated snow at the Arctic Aeromedical Laboratory, near Fairbanks, others of snow blocks on sea ice at Barter Island (70 08 N, 143 40 W). Pneumatic forms such as inflated weather balloons were useful, but not indispensable, in the loose snow type. Due to compaction, the density of the snow increased during construction from 0.22 gm/cu cm to 0.28 gm/cu cm and the hardness range from 8-80 gm/sq cm to 200-850 gm/sq cm Air temperatures in and outside both occupied and unoccupied shelters of this type (tabulated) demonstrate the efficacy of snow as an insulator and thermal advantages derived from ground heat. Inside temperature close to that at the ground surface, remained nearly constant (15-20 F) while outside temperatures ranged from -12 to -40 F Shelters were warmer during occupancy. In the snow-block shelters built on bare sea ice and on an 18 in deep drift, temperatures varied from 10-19 F at the top, 7-20 F in the center, and 7-18 F at the floor, while outside temperatures ranged from -2 to -5 F; thus subnivean warmth on sea ice can also be utilized. The temperature in a 2.5 ft deep trench in a drift, covered with a roof of horizontal snow blocks, was 20-24 F at the sleeping level 6 in above the floor
Study of HST counterparts to Chandra X-ray sources in the Globular Cluster M71
We report on archival Hubble Space Telescope (HST) observations of the
globular cluster M71 (NGC 6838). These observations, covering the core of the
globular cluster, were performed by the Advanced Camera for Surveys (ACS) and
the Wide Field Planetary Camera 2 (WFPC2). Inside the half-mass radius (r_h =
1.65') of M71, we find 33 candidate optical counterparts to 25 out of 29
Chandra X-ray sources while outside the half-mass radius, 6 possible optical
counterparts to 4 X-ray sources are found. Based on the X-ray and optical
properties of the identifications, we find 1 certain and 7 candidate
cataclysmic variables (CVs). We also classify 2 and 12 X-ray sources as certain
and potential chromospherically active binaries (ABs), respectively. The only
star in the error circle of the known millisecond pulsar (MSP) is inconsistent
with being the optical counterpart. The number of X-ray faint sources with
L_x>4x10^{30} ergs/s (0.5-6.0 keV) found in M71 is higher than extrapolations
from other clusters on the basis of either collision frequency or mass. Since
the core density of M71 is relatively low, we suggest that those CVs and ABs
are primordial in origin.Comment: 12 pages, 6 figures. Accepted for publication in Astronomy and
Astrophysic
ΠΡΠ±ΠΎΡ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π° ΡΠΈΠ»ΡΡΡΠ° Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ Π‘ΠΠ‘-ΠΌΠ΅Ρ Π°Π½ΠΎΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΎΠ² Π΄Π»Ρ ΡΠ°ΡΠΈΠ½ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΊΡΠ΅ΠΌΠ½ΠΈΡ
Π Π°Π±ΠΎΡΠ° ΠΏΠΎΡΠ²ΡΡΠ΅Π½Π° ΠΏΠΎΠ΄Π±ΠΎΡΡ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π° ΡΠΈΠ»ΡΡΡΠ°, ΠΏΠΎΠ»ΡΡΠ°Π΅ΠΌΠΎΠ³ΠΎ Ρ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ΠΌ ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΠΉ ΠΌΠ΅Ρ
Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠΉ Π°ΠΊΡΠΈΠ²Π°ΡΠΈΠΈ ΠΈ ΡΠ°ΠΌΠΎΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½ΡΡΡΠ΅Π³ΠΎΡΡ Π²ΡΡΠΎΠΊΠΎΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ½ΠΎΠ³ΠΎ ΡΠΈΠ½ΡΠ΅Π·Π° (Π‘ΠΠ‘), Π° ΡΠ°ΠΊΠΆΠ΅ ΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΈΡ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΠΈ ΠΏΡΠΎΡΠ΅ΠΊΠ°Π½ΠΈΡ ΡΠ΅Π°ΠΊΡΠΈΠΈ Π² ΡΠ΅ΠΆΠΈΠΌΠ΅ Π‘ΠΠ‘ ΠΌΠ΅ΠΆΠ΄Ρ Π²ΡΠ±ΡΠ°Π½Π½ΡΠΌΠΈ ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΠ°ΠΌΠΈ.The work is devoted to the selection of the filter material obtained with the use of the technologies of mechanical activation and self-propagating high-temperature synthesis (SHS), as well as the establishment of the possibility of the reaction in the SHS mode between the selected components
ΠΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ Π·ΠΎΠ½ ΡΡΡΠ°Π»ΠΎΡΡΠ½ΠΎΠ³ΠΎ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ ΡΠ½Π΅ΠΊΠΎΠ²
Π¨Π½Π΅ΠΊ - ΠΎΡΠ½ΠΎΠ²Π½ΠΎΠΉ ΡΠ°Π±ΠΎΡΠΈΠΉ ΠΎΡΠ³Π°Π½ ΠΌΠ°ΡΠΈΠ½ Π΄Π»Ρ ΠΏΠ΅ΡΠ΅ΡΠ°Π±ΠΎΡΠΊΠΈ ΠΎΡΡ
ΠΎΠ΄ΠΎΠ² - ΡΠΊΡΡΡΡΠ΄Π΅ΡΠΎΠ². ΠΡ ΠΊΠ°ΡΠ΅ΡΡΠ²Π° Π΅Π³ΠΎ ΠΈΠ·Π³ΠΎΡΠΎΠ²Π»Π΅Π½ΠΈΡ Π·Π°Π²ΠΈΡΠΈΡ ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄ΠΈΡΠ΅Π»ΡΠ½ΠΎΡΡΡ ΡΠ΅Ρ
Π° ΠΈ ΡΠ΅Π»ΠΎΡΡΠ½ΠΎΡΡΡ ΠΊΠΎΡΠΏΡΡΠ° ΠΌΠ°ΡΠΈΠ½Ρ. ΠΡΠΈ ΠΏΠ΅ΡΠ΅ΡΠ°Π±ΠΎΡΠΊΠ΅ ΠΌΠ½ΠΎΠ³ΠΎΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΠ½ΠΎΠ³ΠΎ ΡΡΡΡΡ, ΠΊΠΎΡΠΎΡΡΠΌ ΡΠ²Π»ΡΠ΅ΡΡΡ Refuse Derived Fuel - ΡΡΠΎ ΠΎΠ±ΡΠ΅Π΅ Π½Π°Π·Π²Π°Π½ΠΈΠ΅ Π°Π»ΡΡΠ΅ΡΠ½Π°ΡΠΈΠ²Π½ΡΡ
Π²ΠΈΠ΄ΠΎΠ² ΡΠΎΠΏΠ»ΠΈΠ²Π°, ΠΏΠΎΠ»ΡΡΠ°Π΅ΠΌΡΡ
ΠΏΡΠΈ ΠΏΠ΅ΡΠ΅ΡΠ°Π±ΠΎΡΠΊΠ΅ ΠΎΡΡ
ΠΎΠ΄ΠΎΠ². Π ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΡΡΡΡΡ ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΠ΅ΡΡΡ ΠΏΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΈ Π»ΡΠ±ΠΎΠΉ ΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΈΠΉ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»: ΡΠ΅Π»Π»ΡΠ»ΠΎΠ·Π°, ΡΠ΅Π·ΠΈΠ½Π°, ΠΏΠ»Π°ΡΡΠΈΠΊ, ΠΊΠΎΠΆΠ°, Π΄Π΅ΡΠ΅Π²ΠΎ, ΠΏΠΈΡΠ΅Π²ΡΠ΅ Π·Π°ΠΌΠ΅Π½ΠΈΡΠ΅Π»ΠΈ. Π ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΈ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ ΠΏΡΠΈΠΌΠ΅Ρ Π½Π° Π±Π°Π·Π΅ ΡΠ°Π±ΠΎΡΡ Ρ RDF-ΡΡΡΡΠ΅ΠΌ ΠΡΡΠΎΡΠΎΠΏΠ΅ΡΠ΅ΡΠ°Π±Π°ΡΡΠ²Π°ΡΡΠ΅Π³ΠΎ ΠΊΠΎΠΌΠ±ΠΈΠ½Π°ΡΠ° "Π―Π½ΠΈΠ½ΠΎ", ΠΠ΅Π½ΠΈΠ½Π³ΡΠ°Π΄ΡΠΊΠ°Ρ ΠΎΠ±Π»Π°ΡΡΡ. ΠΠΌΠ΅Π½Π½ΠΎ ΠΏΡΠΈ ΡΠ°Π±ΠΎΡΠ΅ Ρ ΡΠ°ΠΊΠΈΠΌΠΈ Π²ΡΡΠΎΠΊΠΎΠ°Π±ΡΠ°Π·ΠΈΠ²Π½ΡΠΌΠΈ ΠΎΡΡ
ΠΎΠ΄Π°ΠΌΠΈ Π²ΠΎΠ·Π½ΠΈΠΊΠ°Π΅Ρ Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΠΎΡΡΡ ΠΌΠ½ΠΎΠ³ΠΎΠΊΡΠ°ΡΠ½ΠΎ ΠΏΠΎΠ²ΡΡΠ°ΡΡ ΡΠ΅ΡΡΡΡ ΡΠ½Π΅ΠΊΠΎΠ² Π·Π° ΡΡΠ΅Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΡ Π½ΠΎΠ²ΡΡ
ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΠΉ ΠΎΠ±ΡΠ°Π±ΠΎΡΠΊΠΈ ΠΌΠ΅ΡΠ°Π»Π»ΠΎΠ², ΡΠ°ΠΊ ΠΊΠ°ΠΊ Π² ΡΠΎΡΡΠ°Π²Π΅ Π΄Π°Π½Π½ΠΎΠ³ΠΎ ΡΡΡΡΡ ΠΌΠΎΠ³ΡΡ Π²ΡΡΡΠ΅ΡΠ°ΡΡΡΡ ΠΌΠ΅ΡΠ°Π»Π»ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΡ ΠΈ ΡΡΡΠ΄Π½ΠΎ ΡΠ°Π·ΠΌΠ°Π»ΡΠ²Π°Π΅ΠΌΡΠ΅ ΡΠΈΠ»ΠΈΠΊΠ°ΡΡ.Screw - the main working organ of machines for processing waste - extruders. From the quality of its production depends the productivity of the shop and the integrity of the machine body. When refining a multicomponent raw material, which is Refuse Derived Fuel - this is the general name for alternative fuels obtained from recycling. As raw material, almost any organic material is used: cellulose, rubber, plastic, leather, its substitutes. The study used an example based on work with RDF-raw materials of the Janino Refuse Processing Plant. Leningrad region. It is when working with such highly abrasive waste that it becomes necessary to increase the service life of screw augmentedly by using new processing technologies, since metal components and hard-to-break silicates can occur in the composition of this raw material
IXPE Mirror Module Assemblies
Expected to launch in 2021 Spring, the Imaging X-ray Polarimetry Explorer (IXPE) is a NASA Astrophysics Small Explorer Mission with significant contributions from the Italian space agency (ASI). The IXPE observatory features three identical x-ray telescopes, each comprised of a 4-m-focal-length mirror module assembly (MMA, provided by NASA Marshall Space Flight Center) that focuses x rays onto a polarization-sensitive, imaging detector (contributed by ASI-funded institutions). This paper summarizes the MMAs design, fabrication, alignment and assembly, expected performance, and calibration plans
C, Cl and H compound-specific isotope analysis to assess natural versus Fe(0) barrier-induced degradation of chlorinated ethenes at a contaminated site
Compound-specific isotopic analysis of multiple elements (C, Cl, H) was tested to better assess the effect of a zero-valent iron-permeable reactive barrier (ZVI-PRB) installation at a site contaminated with tetrachloroethene (PCE) and trichloroethene (TCE). The focus was on (1) using 13C to evaluate natural chlorinated ethene biodegradation and the ZVI-PRB efficiency; (2) using dual element 13C-37Cl isotopic analysis to distinguish biotic from abiotic degradation of cis-dichloroethene (cis-DCE); and (3) using 13C-37Cl-2H isotopic analysis of cis-DCE and TCE to elucidate different contaminant sources. Both biodegradation and degradation by ZVI-PRB were indicated by the metabolites that were detected and the 13C data, with a quantitative estimate of the ZVI-PRB efficiency of less than 10% for PCE. Dual ele- ment 13C-37Cl isotopic plots confirmed that biodegradation was the main process at the site including the ZVI-PRB area. Based on the carbon isotope data, approximately 45% and 71% of PCE and TCE, respec- tively, were estimated to be removed by biodegradation. 2H combined with 13C and 37Cl seems to have identified two discrete sources contributing to the contaminant plume, indicating the potential of 2 H to discriminate whether a compound is of industrial origin, or whether a compound is formed as a daughter product during degradation
Discovery of Oxygen Kalpha X-ray Emission from the Rings of Saturn
Using the Advanced CCD Imaging Spectrometer (ACIS), the Chandra X-ray
Observatory (CXO) observed the Saturnian system for one rotation of the planet
(~37 ks) on 20 January, 2004, and again on 26-27 January, 2004. In this letter
we report the detection of X-ray emission from the rings of Saturn. The X-ray
spectrum from the rings is dominated by emission in a narrow (~130 eV wide)
energy band centered on the atomic oxygen K-alpha fluorescence line at 0.53
keV. The X-ray power emitted from the rings in the 0.49-0.62 keV band is 84 MW,
which is about one-third of that emitted from Saturn disk in the photon energy
range 0.24-2.0 keV. Our analysis also finds a clear detection of X-ray emission
from the rings in the 0.49-0.62 keV band in an earlier (14-15 April, 2003)
Chandra ACIS observation of Saturn. Fluorescent scattering of solar X-rays from
oxygen atoms in the H2O icy ring material is the likely source mechanism for
ring X-rays, consistent with the scenario of solar photo-production of a
tenuous ring oxygen atmosphere and ionosphere recently discovered by Cassini.Comment: 14 pages, 5 figures Astrophys. J Lett., in pres
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