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141.
J. Bremer P. Hoffmann A. H. Manson C. E. Meek R. Rüster W. Singer 《Annales Geophysicae》1997,14(12):1317-1327
Simultaneous observations of polar mesosphere summer echoes (PMSE) have been carried out during summer 1994 in northern Norway using three radars on different frequencies: the ALOMAR SOUSY radar at Andenes on 53.5 MHz, the EISCAT VHP radar at Tromsø on 224 MHz and the MF radar at Tromsø on 2.78 MHz. During the common measuring period in July/August 1994, PMSE could be detected at 224 and 53.5 MHz, and there are strong hints that PMSE also occur at 2.78 MHz. Reliable correlations between hourly backscattered power values indicate that the PMSE structures have zonal extensions of more than 130 km and can be detected at very different scales (half wavelength) between 0.67 (EISCAT VHP radar) and 54 m (MF radar). Using the wind values derived by the MF radar it can be shown that the mesospheric wind field influences the structure of PMSE. The diurnal variation of PMSE is strongly connected with tidal-wind components, whereas spatial differences of PMSE can partly be explained by the mean wind field. 相似文献
142.
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144.
A method is described for determining the course of inhibition curves substantiating the influence of some inorganic (Cr (VI)) and organic substances (phenol, synthetic tanning agents) on respiratory activity of heterogeneous biomass (activated sludge). Presented results prove that calculated inhibition curves have the course of a normal distribution function. 相似文献
145.
Lisse C. M. Fernández Y. R. A'hearn M. F. Kostiuk T. Livengood T. A. Käufl H. U. Hoffmann W. F. Dayal A. Ressler M. E. Hanner M. S. Fazio G. G. Hora J. L. Peschke S. B. Grün E. Deutsch L. K. 《Earth, Moon, and Planets》1997,78(1-3):251-257
We present infrared imaging and photometry of the bright, giant comet C/1995 O1 (Hale-Bopp). The comet was observed in an
extended infrared and optical observing campaign in 1996–1997. The infrared morphology of the comet was observed to change
from the 6 to 8 jet “porcupine” structure in 1996 to the “pinwheel” structure seen in 1997; this has implications for the
position of the rotational angular momentum vector. Long term light curves taken at 11.3 μm indicate a dust production rate
that varies with heliocentric distance as ∶ r−1.4. Short term light curves taken at perihelion indicate a rotational periodicity of 11.3 hours and a projected dust outflow
speed of ∶ 0.4 km s−1. The spectral energy distribution of the dust on October 31, 1996 is well modeled by a mixture of 70% silicaceous and 30%
carbonaceous non-porous grains, with a small particle dominated size distribution like that seen for comet P/Halley (McDonnell
et al., 1991), an overall dust production rate of 2 × 105 kg s−1, a dust-to-gas ratio of ∶5, and an albedo of 39%.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
146.
The transition region and coronal explorer 总被引:5,自引:0,他引:5
Handy B.N. Acton L.W. Kankelborg C.C. Wolfson C.J. Akin D.J. Bruner M.E. Caravalho R. Catura R.C. Chevalier R. Duncan D.W. Edwards C.G. Feinstein C.N. Freeland S.L. Friedlaender F.M. Hoffmann C.H. Hurlburt N.E. Jurcevich B.K. Katz N.L. Kelly G.A. Lemen J.R. Levay M. Lindgren R.W. Mathur D.P. Meyer S.B. Morrison S.J. Morrison M.D. Nightingale R.W. Pope T.P. Rehse R.A. Schrijver C.J. Shine R.A. Shing L. Strong K.T. Tarbell T.D. Title A.M. Torgerson D.D. Golub L. Bookbinder J.A. Caldwell D. Cheimets P.N. Davis W.N. Deluca E.E. McMullen R.A. Warren H.P. Amato D. Fisher R. Maldonado H. Parkinson C. 《Solar physics》1999,187(2):229-260
The Transition Region and Coronal Explorer (TRACE) satellite, launched 2 April 1998, is a NASA Small Explorer (SMEX) that
images the solar photosphere, transition region and corona with unprecedented spatial resolution and temporal continuity.
To provide continuous coverage of solar phenomena, TRACE is located in a sun-synchronous polar orbit. The ∼700 Mbytes of data
which are collected daily are made available for unrestricted use within a few days of observation. The instrument features
a 30-cm Cassegrain telescope with a field of view of 8.5×.5 arc min and a spatial resolution of 1 arc sec (0.5 arc sec pixels).
TRACE contains multilayer optics and a lumogen-coated CCD detector to record three EUV wavelengths and several UV wavelengths.
It observes plasmas at selected temperatures from 6000 K to 10 MK with a typical temporal resolution of less than 1 min. 相似文献
147.
HEAO-B (Einstein) satellite measurements with the Imaging Proportional Counter revealed the W UMa binary system TZ Bootis as an X-ray source. It is estimated that the luminosity ratioL
x/Lvof this system is about 10–3.8 indicating that TZ Bootis is in the transition region between A- and W-type W UMa systems. 相似文献
148.
I. Semeniuk A. Schwarzenberg-Czerny H. Duerbeck M. Hoffmann J. Smak K. Stepien J. Tremko 《Astrophysics and Space Science》1987,130(1-2):167-174
An analysis of data spanning 24 years shows that a secondary 20m periodicity is a persistent feature in photometric observations of TT Ari. This period decreases from 27m in 1961 to 17m in 1985. The 4d beat period of 3
.
h
2 photometric and 3
.
h
3 spectroscopic periods is also apparent in observations of 1966.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986. 相似文献
149.
Th. Armbruster E. Libowitzky M. Auernhammer P. Bauerhansl Ch. Hoffmann E. Irran A. Kurka H. Rosenstingl L. Diamond 《Mineralogy and Petrology》1995,52(1-2):113-126
Summary The crystal structure of blue bazzite (space group P6/mcc, Z = 2, = 9.501(1),c = 9.178(1) Å) with the composition Be3(Sc1.25Fe3+
0.43Mg0.32Mn0.03Al0.02)=2.05 Si6O18[Na0.32(n H2O)] was refined from X-ray single-crystal data with 422 unique reflections to R = 2.2%. The structure is of the beryl type with octahedra strongly compressed parallel to the c-axis. The octahedral Me-O distance in bazzite is 2.080 A compared to 1.904 Å in beryl. The flattening of octahedra leads to a larger a cell dimension in bazzite compared to beryl (9.209 A). Two-valent cations (mainly Mg) in octahedral coordination are charge balanced by Na at (0, 0, 0) in the structural channels. Polarized single-crystal IR-spectra recorded between 400 and 8000 cm–1 indicate that H2O in the structural channels is oriented with the H-H vector perpendicular to thec-axis. The IR-spectra show more absorption bands than known for type II H2O in beryl thus the existence of more than one H2O species or even OH-groups is very likely.Refractive indices of the same bazzite were measured using a spindle-stage and employing the wavelength-temperature variation method yielding no = 1.6279(3), ne = 1.6066(5) for 589 nm at 25°C. The birefringence = 0.0213 is significantly larger than the one of near end-member beryl ( = 0.0047). This high birefringence of bazzite is related to the electronic polarizability of octahedral Sc and Fe which increase no at a stronger rate than ne. Transition metals in bazzite are also responsible for a higher refractive index dispersion than found for beryl.
Kristallchemie und optische eigenschaften des bazzits aus dem Furkabasistunnel
Zusammenfassung Die Kristallstruktur eines blauen Bazzits (Raumgruppe P6/mcc, Z = 2,a = 9.501(1),c = 9.178(1) Å) mit der Zusammensetzung Be3(Sc1.25Fe3+ 0.43Mg0.32Mn0.03Al0.02)2=2.05 Si6)O18[Na0.32(n H2O)] wurde von Röntgeneinkristalldaten mit 422 Reflexen zu R = 2.2% verfeinert. Die Struktur ist die des Berylltyps mit der Besonderheit, daß die Oktaeder entlang der c-Achse stark zusammengedrückt sind. Die oktaedrischen Me-O Abstände im Bazzit betragen 2.080 Å, im Gegensatz zu 1.904Å im Beryll. Die Stauchung der Oktaeder im Bazzit führt zu einer längeren a-Achse als im Beryll (9.209 Å). Zweiwertige Kationen (vor allem Mg) in oktaedrischer Koordination werden durch Na auf (0, 0, 0), in den strukturellen Kanalen, neutralisiert. Polarisierte Einkristall-IR-Spektren zwischen 400 and 8000 cm–1 zeigen, daß H2O Moleküle in den strukturellen Kanalen mit dem H-H Vektor senkrecht zur c-Achse orientiert sind. Die IR-Spektren weisen außerdem mehr Absorptionsbanden auf, als für den H2O Typ II bekannt sind, sodaß entweder mehr als eine H2O Spezies oder sogar OH-Gruppen sehr wahrscheinlich sind.Brechungsindizes am gleichen Bazzit wurden auf einem Spindeltisch mit der Wellenlängen-Temperatur Variationsmethode gemessen und ergaben no = 1.6279(3), ne = 1.6066(5) bei 589 nm und 25 °C. Die Doppelbrechung A = 0.0210 ist deutlich höher als für einen nahezu Endgliedberyll (A = 0.0047). Diese hohe Doppelbrechung des Bazzits wird durch die elektronische Polarisierbarkeit von oktaedrischem Sc und Fe verursacht, die no starker ansteigen läßt als ne. Übergangselemente im Bazzit sind auch für die höhere Dispersion der Brechungsindizes als im Beryll verantwortlich.相似文献
150.
The effects of rainfall structure and atmosphericcirculation variability on streamflow in the AlzetteRiver basin (Grand Duchy of Luxembourg, Europe) wereinvestigated. Evidence is presented regarding the local-scalesensitivity of the Alzette River basin to large-scalechanges in atmospheric circulation. Since the1950s, there has been a marked increase in thecontribution of the westerly component of atmosphericcirculation to rainfall. These changes in atmosphericcirculation are on a par with an increase in rainfallintensity and duration, which has induced a significantincrease in the winter maximum daily storm flow in theAlzette River basin since the 1970s. 相似文献