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101.
Th. Henning 《Astrophysics and Space Science》1985,114(2):401-411
A radiative transfer model for newly formed hot stars surrounded by optically thick dust shells is applied to a number of compact infrared sources. The model parameters are derived by fitting the synthetic spectra to the observed one between 8 and 13 m and used to derive additional properties of the shells and the embedded stars. 相似文献
102.
Henning Lorenz Peep Männik David Gee Vasilij Proskurnin 《International Journal of Earth Sciences》2008,97(3):519-547
The Severnaya Zemlya Archipelago is located at 80°N near the continental shelf break, between the Kara and Laptev seas. Sedimentary
successions of Neoproterozoic and Palaeozoic age dominate the bedrock geology. Together with Northern Tajmyr, Severnaya Zemlya
constitutes the main land areas of the North Kara Terrane (NKT), which is inferred here to have been a part of the Timanide
margin of Baltica, i.e. an integral part of Baltica at least since the Vendian. Vendian turbidites derived from the Timanide
Orogen are inferred to have been deposited on Neoproterozoic greenschist facies, granite-intruded basement. Shallow-water
siliclastic deposition in the Early to Mid-Cambrian was followed by highly organic-rich shales in the Late Cambrian and influx
of more turbidites. An episode of folding, the Kan’on River deformation, separates these formations from the overlying Tremadocian
conglomerates and sandstones. In the Early Ordovician, rift-related magmatic rocks accompanied the deposition of variegated
marls, sandstones, carbonates and evaporites. Dark shales and gypsiferous limestones characterise the Mid-Ordovician. Late
Ordovician quartz-sandstones mark a hiatus, followed by carbonate rocks that extend up into and through most of the Silurian.
The latter give way upwards into Old Red Sandstones, which are inferred to have been deposited in a Caledonian foreland basin.
Deformation, reaching the area in the latest Devonian or earliest Carboniferous and referred to as the Severnaya Zemlya episode,
is thought to be Caledonian-related. The dominating E-vergent structure was controlled by décollement zones in Ordovician
evaporite-bearing strata; detachment folds and thrusts developed in the west and were apparently impeded by a barrier of Ordovician
igneous rocks in the east. Below the décollement zones, the Neoproterozoic to Early Ordovician succession was deformed into
open to close folds. The exposed strata in the lower structural level have been juxtaposed with those in the upper structural
level along the major N-trending Fiordovoe Lake Fault Zone, which involved several kilometres of dextral strike-slip movement
and downthrow to the west. A major Early Carboniferous unconformity separates the folded Mid-Palaeozoic and older rocks from
overlying Carboniferous formations, as on Franz Joseph Land and Svalbard. Subsequent latest Palaeozoic to Early Mesozoic orogeny,
as on Taimyr, apparently had little influence on the Severnaya Zemlya successions. 相似文献
103.
Electrochemical Characterization of the Surface of Activated Carbon Used in Water Treatment Plants. We tried to measure electrochemically those properties of activated carbons which are important for using them for water purification. A success was achieved with the electrochemical immersion potential Ui which is found to be a function of concentration of functional surface groups on the carbon surface. However, the expected direct proportionality for inert surfaces between BET surface area and amount of charge measured in recharge processes has not been observed. 相似文献
104.
The Becklin-Neugebauer objects are identified by means of a wide range of observable features as a separate class of very young and massive stars surrounded by optically thick dust shells. We show that they evolutionarily connect real protostars to compactHii regions. We give criteria which should be appropriate to segregate the BN objects from compactHii regions. Finally, we describe the structure of a typical BN object.Paper presented at a Workshop on The Role of Dust in Dense Regions of Interstellar Matter, held at Georgenthal, G.D.R., in March, 1986. 相似文献
105.
International Journal of Earth Sciences - 相似文献
106.
107.
Shipley Thomas H. Bangs Nathan L. Henning Alison T. 《Marine Geophysical Researches》1998,20(6):479-494
In deep ocean settings where water depth greatly exceeds the source-to-receiver length, the geometry is insufficient for accurate determinations of velocity from reflection-moveout. However, velocities are crucial for estimates of physical properties and image processing. Focusing analyses with conventional post-stack two-dimensional migration improves images, but does not produce geologically meaningful velocities except in the special case of a two-dimensional earth. For the more general case of the three-dimensional earth there is no a priori method to determine the degree of geometrical complexity. We present a technique using a short-offset three-dimensional (3-D) data set over the 5 km deep trench west of the Lesser Antilles. These data illustrate highly sensitive post-stack 3-D focusing analyses (± 20 m s–1 interval velocities), and the relationship of these seismically derived velocities to rock velocities. In our Barbados example we were able to establish the presence of a widespread 80-160 m thick low-velocity zone at and above the main low-angle fault. This observation suggests the water-rich décollement leaks water into the overlying sections. Also evident is a low-velocity section associated with turbidite sands. These results are confirmed with sparse logging data and well samples. Deep-water short offset 3-D experiments provide a potentially effective approach for velocity estimation, replacing the operational complexity of long-offsets with simpler short-offset techniques. In areas of structural complications and abundant diffracted energy, it is a surprisingly accurate method, utilizing the high fidelity 3-D wavefield and the information carried in zero-offset diffraction ellipsoids. The velocity used to properly collapse a diffraction ellipsoid is explicitly the velocity of propagation in the media since the travel path is known exactly. Thus, the derived velocities should closely represent rock velocities, unlike the 2-D case where the propagation geometry is not known. 相似文献
108.
Anna Stepanova Ekaterina Taldenkova Henning A. Bauch 《Boreas: An International Journal of Quaternary Research》2012,41(4):557-577
Fossil ostracod assemblages were investigated in five AMS 14 C‐dated cores from various water depths of the Laptev and Kara seas ranging from the upper continental slope (270 m) to the present‐day shelf depth (40 m). Six fossil assemblages were distinguished. These represent the varying environmental conditions at the North Siberian continental margin since about 18 ka. In the cores from the shelf the ostracod assemblages reflect the gradual transition from an estuarine brackish‐water environment to modern marine conditions since 12.3 ka, as induced by the regional early Holocene transgression. The core from the upper continental slope dates back to c. 17.6 ka and contains assemblages that are absent in the shelf cores. The assemblage older than 10 ka stands out as a specific community dominated by relatively deep‐water Arctic and North Atlantic species that also contains euryhaline species. Such an assemblage provides evidence for past inflows of Atlantic‐derived waters from as early as c. 17.2 ka, probably facilitated by upwelling in coastal polynyas, and a considerable riverine freshwater influence with enhanced surface water stratification owing to the proximity of the palaeocoastline until early Holocene times. In all studied cores, relative increases in euryhaline species dominant in the inner‐shelf regions are recorded in the mid–late Holocene sediments (<7 ka), which otherwise already contain modern‐like ostracod assemblages with relatively deep‐water species. This observation suggests euryhaline species to be largely sea‐ice‐ and/or iceberg‐rafted and therefore may provide evidence for a climate cooling trend. 相似文献
109.
Formation of a small impact structure discovered within the Agoudal meteorite strewn field,Morocco
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C. A. Lorenz M. A. Ivanova N. A. Artemieva D. A. Sadilenko H. Chennaoui Aoudjehane I. A. Roschina A.V. Korochantsev M. Humayun 《Meteoritics & planetary science》2015,50(1):112-134
A relic impact structure was recognized within the strewn field of the Agoudal iron meteorite. The heavily eroded structure has preserved shatter cones in a limestone basement, and remnants of autochthonous and allochthonous breccias. Fragments of iron incorporated into the allochthonous breccia have a chemical composition (Ni = 5.16 wt%, Ir = 0.019 ppm) similar to that of the Agoudal meteorite, supporting a syngenetic origin of the strewn field and the impact structure. The total recovered mass of Agoudal meteorite fragments is estimated at approximately 500 kg. The estimated size of the SE–NW‐oriented strewn field is 6 × 2 km. Model calculations with minimal preatmospheric size show that a similar meteorite strewn field plus one small crater with observed shock effects could be formed by fragmentation of a meteoroid approximately 1.4 m in diameter with an impact angle of approximately 60° from the horizontal. However, the most probable is an impact of a larger, 3–4 m diameter meteoroid, resulting a strewn field with approximately 10 craters, 10–30 m in diameter each, plus numerous meteorite fragments. The calculated scattering area of meteorite shrapnel ejected from these impact craters could completely cover the observed strewn field of the Agoudal meteorite. 相似文献
110.
Bryan W. Stiles Scott Hensley David M. Bates Alex Hayes Ralph D. Lorenz Philip S. Callahan William T.K. Johnson Jonathan I. Lunine Michael Janssen Richard D. West the Cassini RADAR Team 《Icarus》2009,202(2):584-598
A technique, referred to as SARTopo, has been developed for obtaining surface height estimates with 10 km horizontal resolution and 75 m vertical resolution of the surface of Titan along each Cassini Synthetic Aperture Radar (SAR) swath. We describe the technique and present maps of the co-located data sets. A global map and regional maps of Xanadu and the northern hemisphere hydrocarbon lakes district are included in the results. A strength of the technique is that it provides topographic information co-located with SAR imagery. Having a topographic context vastly improves the interpretability of the SAR imagery and is essential for understanding Titan.SARTopo is capable of estimating surface heights for most of the SAR-imaged surface of Titan. Currently nearly 30% of the surface is within 100 km of a SARTopo height profile. Other competing techniques provide orders of magnitude less coverage.We validate the SARTopo technique through comparison with known geomorphological features such as mountain ranges and craters, and by comparison with co-located nadir altimetry, including a 3000 km strip that had been observed by SAR a month earlier. In this area, the SARTopo and nadir altimetry data sets are co-located tightly (within 5-10 km for one 500 km section), have similar resolution, and as expected agree closely in surface height. Furthermore the region contains prominent high spatial resolution topography, so it provides an excellent test of the resolution and precision of both techniques. 相似文献