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141.
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143.
Lithospheric mantle signatures as revealed by zircon Hf isotopes of Late Triassic post‐collisional plutons from the central Korean peninsula,and their tectonic implications
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Chang‐Sik Cheong Namhoon Kim Hui Je Jo Moonsup Cho Sung Hi Choi Hongying Zhou Jian‐zhen Geng 《地学学报》2015,27(2):97-105
The Mesozoic tectonic architecture of the Korean peninsula is largely governed by the continental collision between the North and South China blocks. Zircon Hf isotopic compositions presented in this study and whole‐rock geochemical and Sr‐Nd isotope data in the literature collectively suggest that the lithophile‐elements‐enriched signature of the Late Triassic post‐collisional plutons from the Gyeonggi massif in central Korea is a primary feature inherited from the metasomatized mantle lithosphere. Highly negative zircon εHf (t) values (?23 to ?19) of plutons from the middle and eastern parts of the massif indicate an ancient metasomatism of their mantle source. Distinctly higher zircon εHf (t) values (?15 to ?12) from the southwestern plutons are ascribed to a contribution from an accreted component of the South China‐like block. The involvement of asthenospheric mantle is not recognized in zircons from either group. The implications of these isotopic features are discussed in the context of Mesozoic collisional tectonics. 相似文献
144.
145.
Jason Timmons Young Min Cho Timothy Townsend Nicole Berge Debra Reinhart 《Geotechnical and Geological Engineering》2012,30(1):95-105
Commercially available hydraulic total overburden pressure cells were installed in the sand drainage layer of a municipal
solid waste landfill and monitored for a period of 3,110 days. Both overburden pressure and temperature were measured in the
landfill as it was filled with compacted waste. Topographic surveys of the landfill were periodically conducted to measure
the height of waste above the pressure cells and to determine the landfill volume for indirect unit weight estimation. The
average ratio of measured to theoretically-predicted overburden pressure was 0.6, indicating that on average the pressure
cells underestimated the load. The overburden pressure measured near the toe of the landfill was greater than that predicted
by the unit weight of landfilled material, while most of the overburden pressure measurements further inside the landfill
were less than predicted. Several possible causes for this phenomenon are discussed, including the uneven distribution of
forces resulting from the heterogeneous nature of the waste and cover soil. The earth pressure cells were capable of detecting
the placement of individual waste lifts. 相似文献
146.
Performance-based design demands accurate prediction of soil deformation under a working load condition. The nonlinear stress–strain behavior needs to be analyzed quantitatively to advance the understanding of complex soil behavior in the pre-failure condition. The singular value decomposition technique is introduced to quantitatively analyze the compliance matrix representing the strain response envelope (SRE). The rotation of the ellipse of the SRE relates to the anisotropic response of the soil deformation. The off-centered SRE provides evidence of the kinematic hardening plasticity. Quantitative data on the movement of SREs provide us with crucial information to investigate the effect of stress history and the evolution of stiffness anisotropy in soil deformation. 相似文献
147.
Kim Y Cho S Kang HD Kim W Lee HR Doh SH Kim K Yun SG Kim DS Jeong GY 《Marine pollution bulletin》2006,52(6):659-665
The mineralogical effect on the (137)Cs reaction with marine sediment has not been systematically studied yet, even though illite has been known to adsorb Cs preferentially on its frayed edge sites in a low Cs concentration. Ninety-three marine sediment samples were collected near Yangnam, Korea for quantitative X-ray-diffraction (XRD), gamma-ray, and total organic carbon (TOC) analysis. Illite content was in the range of 0-23 wt.% and those of (137)Cs and TOC were minimum detectable activity (MDA) approximately 7.19 Bq/kg-dry and approximately 3.32%, respectively. The illite content in the marine sediment showed a good relationship with the (137)Cs content (R(2)=0.69), but with an increase in the illite content, the relationship became less linear. This trend can be clearly shown in two groups of samples with different size fractions (< and >5Mdvarphi). For the samples of larger particle sizes (low contents of illite), the relationship is linear, but for the samples of the smaller particle sizes (high illite content) it is less linear with a decreased slope, indicating that increase in illite content does not significantly contribute to the fixation of (137)Cs in marine sediment. Rather, the TOC has a more linear relationship with (137)Cs content with no slope change in all particle size ranges. This may indicate that humic materials in marine sediment block the access of (137)Cs to the frayed edge site and reduces the adsorption of (137)Cs on illite and that the organic materials in marine sediment play more important roles in adsorbing Cs than illite. 相似文献
148.
M. Dobbs N.W. Halverson P.A.R. Ade K. Basu A. Beelen F. Bertoldi C. Cohalan H.M. Cho R. Güsten W.L. Holzapfel Z. Kermish R. Kneissl A. Kovcs E. Kreysa T.M. Lanting A.T. Lee M. Lueker J. Mehl K.M. Menten D. Muders M. Nord T. Plagge P.L. Richards P. Schilke D. Schwan H. Spieler A. Weiss M. White 《New Astronomy Reviews》2006,50(11-12):960
The apex-sz instrument is designed for the discovery and study of galaxy clusters at mm-wavelengths using the Sunyaev Zel’dovich effect. The receiver consists of 320 superconducting transition edge sensor (TES) bolometers cooled to 250 mK with the combination of a three stage He sorption fridge and mechanical pulse tube cooler. The detectors are instrumented with a frequency domain multiplexing readout system. The receiver is mounted on the 12 m apex telescope located at 5100 m on the Atacama plateau in Chile. For the first light engineering deployment of December 2005, the receiver was configured with a 55 element wedge of the bolometers and operating in the 150 GHz atmospheric window. During the engineering run we achieved significant milestones in our instrumentation development efforts, including celestial observations with a monolithically fabricated TES bolometer array cooled with a mechanical cooler and successful implementation of a SQUID-based MHz AC-biased readout. These technology demonstrations point the way toward future large TES bolometer array instruments. Here we describe the results of this deployment and future plans for the apex-sz instrument. 相似文献
149.
A. Shanmugaraju Y.-J. Moon K.-S. Cho Y.-H. Kim M. Dryer S. Umapathy 《Solar physics》2005,232(1-2):87-103
We report on the detailed analysis of a set of 38 multiple type II radio bursts observed by Culgoora radio spectrograph from
January 1997 to July 2003. These events were selected on the basis of the following criteria: (i) more than one type II were
reported within 30 min interval, (ii) both fundamental and harmonic were identified for each of them. The X-ray flares and
CMEs associated with these events are identified using GOES, Yohkoh SXT, SOHO/EIT, and SOHO/LASCO data. From the analysis
of these events, the following physical characteristics are obtained: (i) In many cases, two type IIs with fundamental and
harmonic were reported, and the time interval between the two type IIs is within 15 min; (ii) The mean values of starting
frequency, drift rate, and shock speed of the first type II are significantly higher than those of the second type II; (iii)
More than 90% of the events are associated with both X-ray flares and CMEs; (iv) Nearly 75% of the flares are stronger than
M1 X-ray class and 50% of CMEs have their widths larger than 200^∘ or they are halo CMEs; (v) While most of the first type
IIs started within the flare impulsive phase, 22 out of 38 second type IIs started after the flare impulsive phase. Weak correlations
are found between the starting and ending frequencies of these type II events. On the other hand, there was no correlation
between two shock speeds between the first and the second type II. Since most of the events are associated with both the flares
and CMEs, and there are no events which are only associated with multiple impulsive flares or multiple mass ejections, we
suggest that the flares and CMEs (front or flank) both be sources of multiple type IIs. Other possibilities on the origin
of multiple type IIs are also discussed. 相似文献
150.
Abstract The effects of condensational heating on the semi‐geostrophic dynamics of frontogenesis are studied using a two‐dimensional deformation model. The model includes water vapour and allows the formation of stratiform clouds. Analysis and numerical results show that heating due to stratiform clouds has the effect of reducing stability to slantwise convection, as found in previous studies (Thorpe and Emanuel, 1985). In addition, heating‐induced potential vorticity and temperature anomalies play a very important role in the frontal circulation. The ageostrophic flow induced by these anomalies tends to reinforce the effect of heating and increases the strength of frontal cloud. The model is also able to produce the low‐level jet maximum ahead of a cold front at an elevated level, in agreement with observations, owing to the explicit condensation scheme used in the model. 相似文献