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81.
Joachim Joseph 《Ocean Dynamics》1950,3(3-4):214-219
Zusammenfassung Mit Durchsichtigkeitsmessungen wird die durch Absorption und Streuung verursachte Gesamtextinktion eines Lichtstrahls im Meerwasser erfat. Als Mazahl der Extinktion eignet sich der physikalische Extinktionskoeffizient. Dem Ziel, geräteunabhängige absolute Mewerte zu erhalten, kann man im sichtbaren Teil des Spektrums durch Eichung der. Durchsichtigkeitsmegeräte mit einem Pulfrich-Photometer näher kommen. Doch bleibt die Genauigkeit der Mewerte besonders durch die Schwerpunktsverschiebungen, die für verschiedene mittlere Durchlässigkeiten des Meerwassers berechnet und tabellarisch zusammengestellt werden, und durch die technischen Eigenschaften der Megeräte und Photoelemente beschränkt. Es wird ein Meprinzip angegeben, das diese Nachteile weitgehend vermeidet und gestattet, auch im UV absolute Extinktionswerte in exakt definierten Punkten des Spektrums zu messen.
Herrn Prof. Dr. G. Wüst gewidmet zum 60. Geburtstag. 相似文献
Quantitative measurements of transparency in the sea
Summary The total extinction of a ray of light in sea water caused by absorption and scattering is ascertained by measuring the transparency. The physical extinction coefficient is suitable to act as an indicator of extinction. In the visible part of the spectrum, it is possible to obtain approximately absolute measurements not influenced by the instruments used, by standardizing the transparency-meters with the aid of a Pulfrich-Photometer. The accuracy of the measurements continues, however, to be limited in particular by the shifting of the centres which are calculated and tabulated for various mean values of transparency of sea water, as well as by the technical properties of the instruments and the rectifier photocell. A principle for measuring transparency free of these deficiencies to a large extent and allowing the measurement of absolute extinction values at exactly defined points of the spectrum, including the ultra-violet, is described.
Herrn Prof. Dr. G. Wüst gewidmet zum 60. Geburtstag. 相似文献
82.
Ohne Zusammenfassung 相似文献
83.
84.
Nonphysical pressure oscillations are observed in finite element calculations of Biot's poroelastic equations in low‐permeable media. These pressure oscillations may be understood as a failure of compatibility between the finite element spaces, rather than elastic locking. We present evidence to support this view by comparing and contrasting the pressure oscillations in low‐permeable porous media with those in low‐compressible porous media. As a consequence, it is possible to use established families of stable mixed elements as candidates for choosing finite element spaces for Biot's equations. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
85.
Existing and planned radiotelescopes working in the millimetre (mm) and sub-millimetre wavelengths range provide the possibility to be used for atmospheric line observations. To scrutinize this potential, we outline the differences and similarities in technical equipment and observing techniques between ground-based aeronomy mm-wave radiometers and radiotelescopes. Comprehensive tables summarizing the technical characteristics of existing and future (sub)-mm radiotelescopes are given. The advantages and disadvantages using radiotelescopes for atmospheric line observations are discussed. In view of the importance of exploring the sub-mm and far-infrared wavelengths range for astronomical observations and atmospheric sciences, we present model calculations of the atmospheric transmission for selected telescope sites (DOME-C/Antarctica, ALMA/Chajnantor, JCMT and CSO on Mauna Kea/Hawaii, KOSMA/Swiss Alpes) for frequencies between 0 and 2000 GHz () and typical atmospheric conditions using the forward model MOLIERE (version 5). For the DOME-C site, the transmission over a larger range of up to 10 THz () is calculated in order to demonstrate the quality of an Earth-bound site for mid-IR observations. All results are available on a dedicated webpage. 相似文献
86.
Joachim Schubart 《Celestial Mechanics and Dynamical Astronomy》2009,104(1-2):85-92
Earlier work indicates a comparatively rapid chaotic evolution of the orbits of some Hilda asteroids that move at the border of the domain occupied by the characteristic parameters of the objects at the 3/2 mean motion resonance. A simple Jupiter–Saturn model of the forces leads to numerical results on some of these cases and allows a search for additional resonances that can contribute to the chaotic evolution. In this context the importance of the secondary resonances that depend on the period of revolution of the argument of perihelion is pointed out. Among the studied additional resonances there are three-body resonances with arguments that depend on the mean longitudes of Jupiter, Saturn, and asteroid, but on slowly circulating angular elements of the asteroid as well, and the frequency of these arguments is close to a rational ratio with respect to the frequency of the libration due to the basic resonance. 相似文献
87.
欧洲中部的易北河流域是典型的湿润半湿润地区。夏季的水资源供给是限制农业生产的因素之一,特别是在具有较高农业生产力水平,而年降水量只有500 mm的黄土地区。通过总结气候变化与水文循环(GLOWA-Elbe)项目第一阶段的成果,根据气候和土地利用变化的各种情景并考虑其不确定性,对未来50 a德国易北河流域水资源供给稳定性作出综合评估。研究表明,欧洲中部必须从自然和社会角度应对未来气候变化情景下产生水资源供给短缺的可能情况。 相似文献
88.
Christian Défarge Pascale Gautret Joachim Reitner Jean Trichet 《Sedimentary Geology》2010,223(3-4):390-391
This is a reply to R.S. Perry and M.A. Sephton's “Reply to comments on defining biominerals and organominerals: direct and indirect indicators of life [Perry et al., Sedimentary Geology, 201, 157–179]” [Sedimentary Geology 213 (2009) 156]. 相似文献
89.
Thomas Wagner Martin Okrusch Stefan Weyer Joachim Lorenz Yann Lahaye Heiner Taubald Ralf T. Schmitt 《Mineralium Deposita》2010,45(3):217-239
The Spessart district (SW Germany), located at the southwestern margin of the Permian Kupferschiefer basin in Central Europe,
hosts abundant stratabound and structurally controlled base metal mineralization. The mineralization styles identified are
(1) stratabound Cu-Pb-Zn-(Ag) ores in Zechstein sedimentary rocks, (2) structurally controlled Cu-As-(Ag) ores in Zechstein
sedimentary rocks, (3) crosscutting Co-Ni-(Bi)-As and Cu-Fe-As veins, (4) stratabound metasomatic Fe-Mn carbonate ores in
Zechstein dolomite, (5) barren barite veins, and (6) Fe-Mn-As veins in Permian rhyolites. Building on previous work that involved
mineralogical, textural, and chemical characterization of the major mineralization types, we have performed a comprehensive
sulfur isotope study that applied both conventional and novel laser-ablation multi-collector inductively coupled plasma mass
spectrometry techniques. The δ34S values of sulfide minerals from the different ore types are consistently negative and highly variable, in the range between
−44.5‰ and −3.9‰, whereas the δ34S values of barite are all positive in the range between 4.7‰ and 18.9‰. Remarkably, stratabound and structurally controlled
mineralization in Zechstein sedimentary rocks has the least negative δ34S values, whereas vein-type deposits have consistently more negative δ34S values. The observed pattern of sulfide δ34S values can be best interpreted in terms of fluid mixing at the basement-cover interface. Hydrothermal fluids originating
from the crystalline basement migrated upward along subvertical fault zones and were periodically injected into groundwaters
that were flowing in the post-Variscan sedimentary cover. These groundwaters had interacted with the Zechstein sedimentary
rocks, resulting in fluids characterized by elevated concentrations of reduced sulfur (with negative δ34S values) and alkaline pH. Repeated mixing between both chemically contrasting fluids caused rapid and efficient precipitation
of sulfide ore minerals in hydrothermal veins with highly variable but distinctly negative δ34S values. 相似文献
90.
Judith Sausse Chrystel Dezayes Louis Dorbath Albert Genter Joachim Place 《Comptes Rendus Geoscience》2010,342(7-8):531-545
This study presents a new deterministic 3D model of the fracture zones observed in the granitic reservoir of the Soultz European geothermal project. The major fracture zones encountered around 6 wells (4550, EPS1, GPK1, GPK2, GPK3 and GPK4) consist in 53 main structures that are located and characterized in terms of size and orientation: 39 fracture zones, 8 microseismic structures and 6 structures derived from vertical seismic profiles are represented in the 3D model using Discrete Fracture Network tools of the gOcad modelling platform (Paradigm?, Earth Decision?). This work illustrates the complexity of 3D fracture zone correlation and interpretation in crystalline rock masses characterized at meter scale (borehole) and at the reservoir scale (kilometer) thanks to geophysical imaging techniques. 相似文献