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11.
Stefan J. Wijnholds A. Ger De Bruyn Jaap D. Bregman Jan Geralt Bij De Vaate 《Experimental Astronomy》2004,17(1-3):59-64
The thousand element array (THEA) system is a phased array system consisting of 1 m2 tiles having 64 Vivaldi elements each, arranged on a regular 8-by-8 grid, which has been developed as a demonstrator of technology and applicability for SKA. In this paper we present imaging results of Galactic neutral hydrogen with THEA. Measurements have been taken using a dense 2-by-2 array of four tiles as a four tile adder. The results are compared with results from the Leiden-Dwingeloo Survey, showing qualitative agreement, but also indicating that further studies are needed on the instrumental characteristics. 相似文献
12.
Spatial variability of hydraulic conductivity and bulk density along a blanket peatland hillslope 总被引：4，自引：0，他引：4
This article presents the results of a field investigation of saturated hydraulic conductivity Ksat and bulk density (ρbd) in an Atlantic blanket bog in the southwest of Ireland. Starting at a peatland stream and moving along an uphill transect toward the peatland interior, ρbd and Ksat were examined at regular intervals. Saturated horizontal hydraulic conductivity (Khsat) and vertical (Kvsat) was estimated at two depths: 10–20 and 30–40 cm below the peat surface, whereas ρbd was estimated for the full profile. We consider two separate zones, one a riparian zone extending 10 m from the stream and a second zone in the bog interior. We found that the Ksat was higher (~10–5 m s–1) in the bog interior than that in the riparian zone (~10–6 m s–1), whereas the converse applied to bulk density, with lowest density (~0.055 g cm–3) at the interior and highest (~0.11 g cm–3) at the riparian zone. In general, we found Khsat to be approximately twice the Kvsat. These results support the idea that the lower Ksat at the margins control the hydrology of blanket peatlands. It is therefore important that the spatial variation of these two key properties be accommodated in hydrological models if the correct rainfall runoff characteristics are to be correctly modelled. Stream flow analysis over 3 years at the peatland catchment outlet showed that the stream runoff was composed of 8% base flow and 92% flood flow, suggesting that this blanket peatland is a source rather than a sink for floodwaters. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
13.
14.
Levent Karadenizli Baki Erdogan Varol Gerçek Saraç Fatma Gedik 《Journal of the Geological Society of India》2016,88(6):773-798
In central eastern Anatolia which is located between Eurasia and Africa, the study of basin developments between late Eocene and early Miocene is of great importance for understanding the process of the closure of the Neo-Tethys Ocean and the formation of strike-slip faults and regional uplift. To study these, three basins were selected: the Sivas-Erzincan, Gürün-Akkisla-Divrigi (GAD), and Malatya basins. The study proposes that the opening of the GAD basin played a key role in the formation of the Ecemis fault, which started developing at the end of early Miocene, and in mountain uplift. All these basins are situated on continental blocks and oceanic crust, arranged from north to south as the Sakarya continent, the Izmir-Ankara-Erzincan ocean (Northern Neo-Tethys), the Kirsehir continent, the inner Tauride ocean, the Munzur-Binboga block, the Maden (=Berit) ocean, the Bitlis-Pütürge block, the Çüngüs ocean and the Arabian continent.The findings indicate that late Eocene-early Miocene successions in these basins were not deposited in foreland basins formed in front of the thrust faults associated with the closure of the ocean, as stated in previous studies. Rather, they were deposited in forearc and backarc basins related to the subduction which was effective until the end of early Miocene. The Sivas-Erzincan and Malatya basins, located on the inner Tauride and Maden (=Berit) oceans, were forearc basins, while the GAD basin situated on the Munzur-Binboga block was a backarc basin. These basins have parallel developments up to the end of early Miocene. While marine sediments were deposited in the Malatya and Sivas-Erzincan basins between late Eocene and early Miocene, terrestrial units began to settle in the GAD basin from the late Eocene and the deposition there is continuous until the end of the early Miocene.Collision of the Arabian and the Anatolian plates at the end of early Miocene (16-18 Ma) produced the left-strike slip Ecemis fault zone, which caused the lateral slip of sedimentary units in the Sivas-Erzincan and GAD basins over hundreds of kilometers. This event produced the first westward tectonic escape of the Anatolian plate prior to the north Anatolian fault (NAF) and the east Anatolian fault (EAF). The Gürün region located in the GAD basin was exhumed in late Miocene and this basin was broken. The Gürün region, which remains on the rising part of the Munzur-Binboga block, is not a different basin as stated earlier, but it is a part of the GAD basin, representing the central part of the GAD basin lake, as indicated by the fine grained deposits (limestones and clay) that occur in the Gürün area. 相似文献
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16.
Ger van Graas T.C. Viets J.W. de Leeuw P.A. Schenck 《Geochimica et cosmochimica acta》1983,47(6):1051-1059
Pyrolysis-mass spectrometry of extracted sediments from the Livello Bonarelli, a thinly laminated carbonate-poor sedimentary unit at the Cenomanian-Turonian boundary, indicates significant differences between the samples. Microscopic investigations and pyrolysis-gas chromatography show a main contribution from marine organic matter for all samples. The composition of the extractable hydrocarbons becomes more complex with increasing organic carbon content of the sediments, indicating increasing anoxicity in the environment of sedimentation.Organic geochemical analyses combined with sedimentological and paleontological data show that the Livello Bonarelli could have been deposited in a paleoenvironment similar to that recently proposed for the Pleistocene Mediterranean sapropels, with an intermittent influx of fresh water leading to stagnation and a high productivity of marine organic matter caused by the transported nutrients. 相似文献
17.
A large set of tower data was used to identify the gap that separates small-scale turbulence and mesoscale structures in the
cospectra of surface fluxes. The cospectra were obtained using a multi-resolution decomposition algorithm. The gap time scale
τ
g
was found by fitting a fifth-order polynomial to the cospectra and identifying special points occurring after the peak at
small scales. In unstable conditions (day) τ
g
was found to fall as the mean wind speed increased, while no such dependence was observed in stable conditions (night). The
gap scale was found to change very weakly with stability both in moderately stable and moderately unstable conditions, with
a sharp drop from about 1100 to 250 s occurring in near-neutral conditions. The vertical fluxes computed at different averaging
intervals were found to correlate exceptionally well with each other, the scatter being somewhat larger during the night.
Although considerable discrepancy may occur for individual records, when averaged over 10 months, the difference in the flux
estimated at 7 to 109 min intervals never exceeded 4%, which is comparable or less than the instrumental error. 相似文献
18.
The effects of phase fractionation on the composition of oils, condensates and gases 总被引：1，自引：0，他引：1
The effects of phase fractionation on the composition of oils, condensates and gases have been studied in the laboratory by a differential evaporation experiment. The experiment was designed to simulate the behaviour of a single-charge petroleum during (upward) migration or in a reservoir undergoing uplift, scenarios thought to be typical for the Norwegian continental shelf. After each pressure reduction step, samples from all phases (oil, condensate, free and associated gas) were collected and analysed. The results show that, in general, small molecules are preferentially enriched in the gas phase, both at elevated pressure and temperature and under standard conditions (15°C, 1 bar). The solvent power of the gas phase for large molecules is drastically reduced at lower pressures (here below approx. 300 bar). Carbon isotope ratios of individual compound are not affected, while variations in isotope ratios of fractions can be explained by changes in the fraction compositions. Individual geochemical parameters behave as can be expected based on the molecular size and structure of the compounds involved. However, a generally valid, quantitative prediction of how geochemical parameters vary as a result of phase fractionation is very difficult, as this will depend not only on the pressure and temperature of fractionation, but also on the composition and amounts of the oil and gas that are involved. The observations from this study confirm the importance of phase fractionation as an important process to consider when interpreting geochemical data for both condensates and oils. 相似文献
19.
Kjeld Van Der Schaaf Chris Broekema Ger Van Diepen Ellen Van Meijeren 《Experimental Astronomy》2004,17(1-3):43-58
Reconfiguration is a key feature characteristic of the LOFAR telescope. Software platforms are utilised to program out the required data transformations in the generation of scientific end-products. Reconfigurable resources nowadays often replace the hard-wired processing systems from the past. This paper describes how this paradigm is implemented in a purely general-purpose telescope back-end. Experiences from high performance computing, stream processing and software engineering have been combined, leading to a state-of-the-art processing platform. The processing platform offers a total processing power of 35 TFlops, which is used to process a sustained input data- stream of 320 Gbps. The architecture of this platform is optimised for streaming data processing and offers appropriate processing resources for each step in the data processing chains. Typical data processing chains include Fourier transformations and correlation tasks along with controlling tasks such as fringe rotation correction. These tasks are defined in a high level programming language and mapped onto the available resources at run time. A scheduling system is used to control a collection of concurrently executing observations, providing each associated application with the appropriate resources to meet its timing constraint and give the integrated system the correct on-line and off-line look and feel. 相似文献
20.
Ger van Graas J.W de Leeuw P.A Schenck J Haverkamp 《Geochimica et cosmochimica acta》1981,45(12):2465-2474
A set of 14 samples—both extracted and unextracted from the Toarcian of the Paris Basin have been investigated using Curie-point pyrolysis-mass spectrometry and Curie-point pyrolysis gas chromatography mass spectrometry. The relative amount of n-alkenes and n-alkanes in the pyrolyzates increases with increasing maximum burial depth of the samples. Comparison of the pyrolysis data of extracted and unextracted samples shows that generation of hydrocarbons from the kerogen starts at a maximum burial depth of ~ 1000m. The increase of pristane and phytane in the extracts of the deeper samples is correlated with the gradual decrease of the characteristic pyrolysis product prist-1-ene. Three samples yield pyrolyzates with high relative amounts of aromatic compounds. This phenomenon probably reflects a different type of contributing organic matter and/or a different environment of sedimentation. 相似文献