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161.
Adi Zitrin Tom Broadhurst Keiichi Umetsu Dan Coe Narciso Benítez Begoña Ascaso Larry Bradley Holland Ford James Jee Elinor Medezinski Yoel Rephaeli Wei Zheng 《Monthly notices of the Royal Astronomical Society》2009,396(4):1985-2002
We present an improved strong-lensing analysis of Cl0024+1654 ( z = 0.39) using deep Hubble Space Telescope ( HST )/Advanced Camera for Surveys (ACS)/NIC3 images, based on 33 multiply-lensed images of 11 background galaxies. These are found with a model that assumes mass approximately traces light, with a low-order expansion to allow for flexibility on large scales. The model is constrained initially by the well-known five-image system ( z = 1.675) and refined as new multiply-lensed systems are identified using the model. Photometric redshifts of these new systems are then used to constrain better the mass profile by adopting the standard cosmological relation between redshift and lensing distance. Our model requires only six free parameters to describe well all positional and redshift data. The resulting inner mass profile has a slope of d log M /d log r ≃−0.55 , consistent with new weak-lensing measurements where the data overlap, at r ≃ 200 kpc/ h 70 . The combined profile is well fitted by a high-concentration Navarro, Frenk & White (NFW) mass profile, C vir ∼ 8.6 ± 1.6 , similar to other well-studied clusters, but larger than predicted with standard Λ cold dark matter (ΛCDM). A well-defined radial critical curve is generated by the model and is clearly observed at r ≃ 12 arcsec, outlined by elongated images pointing towards the centre of mass. The relative fluxes of the multiply-lensed images are found to agree well with the modelled magnifications, providing an independent consistency check. 相似文献
162.
Yunhee Choi Y.-J. Moon Seonghwan Choi Ji-Hye Baek Sungsoo S. Kim K.-S. Cho G. S. Choe 《Solar physics》2009,254(2):311-323
We have examined the relationships among coronal holes (CHs), corotating interaction regions (CIRs), and geomagnetic storms in the period 1996?–?2003. We have identified 123 CIRs with forward and reverse shock or wave features in ACE and Wind data and have linked them to coronal holes shown in National Solar Observatory/Kitt Peak (NSO/KP) daily He i 10?830 Å maps considering the Sun?–?Earth transit time of the solar wind with the observed wind speed. A sample of 107 CH?–?CIR pairs is thus identified. We have examined the magnetic polarity, location, and area of the CHs as well as their association with geomagnetic storms (Dst≤?50 nT). For all pairs, the magnetic polarity of the CHs is found to be consistent with the sunward (or earthward) direction of the interplanetary magnetic fields (IMFs), which confirms the linkage between the CHs and the CIRs in the sample. Our statistical analysis shows that (1) the mean longitude of the center of CHs is about 8°E, (2) 74% of the CHs are located between 30°S and 30°N (i.e., mostly in the equatorial regions), (3) 46% of the CIRs are associated with geomagnetic storms, (4) the area of geoeffective coronal holes is found to be larger than 0.12% of the solar hemisphere area, and (5) the maximum convective electric field E y in the solar wind is much more highly correlated with the Dst index than any other solar or interplanetary parameter. In addition, we found that there is also a semiannual variation of CIR-associated geomagnetic storms and discovered new tendencies as follows: For negative-polarity coronal holes, the percentage (59%; 16 out of 27 events) of CIRs associated with geomagnetic storms in the first half of the year is much larger than that (25%; 6 out of 24 events) in the second half of the year and the occurrence percentage (63%; 15 out of 24 events) of CIR-associated storms in the southern hemisphere is significantly larger than that (26%; 7 out of 27 events) in the northern hemisphere. Positive-polarity coronal holes exhibit an opposite tendency. 相似文献
163.
Soon-Chang Yoon Sang-Woo Kim Suk-Jin Choi In-Jin Choi 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(3):279-286
We investigated the regional-scale relationships between columnar aerosol loads and summer monsoon circulation, and also the precipitation over northeast Asia using aerosol optical depth (AOD) data obtained from the 8-year MODIS, AERONET Sun/sky radiometer, and precipitation data acquired under the Global Precipitation Climatology Project (GPCP). These high-quality data revealed the regional-scale link between AOD and summer monsoon circulation, precipitation in July over northeast Asian countries, and their distinct spatial and annual variabilities. Compared to the mean AOD for the entire period of 2001–2008, the increase of almost 40–50% in the AOD value in July 2005 and July 2007 was found over the downwind regions of China (Yellow Sea, Korean peninsula, and East Sea), with negative precipitation anomalies. This can be attributable to the strong westerly confluent flows, between cyclone flows by continental thermal low centered over the northern China and anticyclonic flows by the western North Pacific High, which transport anthropogenic pollution aerosols emitted from east China to aforementioned downwind high AOD regions along the rim of the Pacific marine airmass. In July 2002, however, the easterly flows transported anthropogenic aerosols from east China to the southwestern part of China in July 2002. As a result, the AOD off the coast of China was dramatically reduced in spite of decreasing rainfall. From the calculation of the cross-correlation coefficient between MODIS-derived AOD anomalies and GPCP precipitation anomalies in July over the period 2001–2008, we found negative correlations over the areas encompassed by 105–115°E and 30–35°N and by 120–140°E and 35–40°N (Yellow Sea, Korean peninsula, and East Sea). This suggests that aerosol loads over these regions are easily influenced by the Asian monsoon flow system and associated precipitation. 相似文献
164.
X. Hernandez Changbom Park B. Cervantes-Sodi Yun-Young Choi 《Monthly notices of the Royal Astronomical Society》2007,375(1):163-170
Using simple dimensional arguments for both spiral and elliptical galaxies, we present formulae to derive an estimate of the halo spin parameter λ for any real galaxy, in terms of common observational parameters. This allows a rough estimate of λ, which we apply to a large volume-limited sample of galaxies taken from the Sloan Digital Sky Survey data base. The large numbers involved (11 597) allow the derivation of reliable λ distributions, as signal adds up significantly in spite of the errors in the inferences for particular galaxies. We find that if the observed distribution of λ is modelled with a lognormal function, as often done for this distribution in dark matter haloes that appear in cosmological simulations, we obtain parameters λ0 = 0.04 ± 0.005 and σλ = 0.51 ± 0.05 , interestingly consistent with values derived from simulations. For spirals, we find a good correlation between empirical values of λ and visually assigned Hubble types, highlighting the potential of this physical parameter as an objective classification tool. 相似文献
165.
Finding the strike direction of fractures using GPR 总被引:3,自引:0,他引:3
Soon Jee Seol Jung-Ho Kim † Yoonho Song‡ Seung-Hwan Chung§ 《Geophysical Prospecting》2001,49(3):300-308
GPR reflection energy varies with antenna orientation relative to the strike and dip of the reflector. This directional dependence of GPR responses was investigated through numerical experiments and was used to estimate the azimuth of fractures and joints. Three antenna configurations were considered in this study: perpendicular-broadside (YY mode), parallel-broadside (XX mode) and cross-polarization (YX mode). The reflection energy in the cross-polarization mode shows a shape characteristic similar to the strike, regardless of the dip angle. Those in the other two modes show quite different amplitudes from the strike, depending on the dip angle. We have developed a strike-direction-finding scheme using data obtained from the three different modes for the same survey line. The azimuth angle of each reflector was displayed in colour on the GPR profile. This scheme was applied to a field survey at a granite quarry in southern Korea. The GPR profiles showed different images of the reflectors depending on the antenna configuration. The estimated azimuths of reflectors obtained using our scheme matched fairly well with those of known fractures and joints. 相似文献
166.
Birger Dahl 《Organic Geochemistry》2004,35(11-12):1551
This paper discusses the occurrence of 28,30-dinor-17α,18α,21β-hopane (bisnorhopane) in stratigraphically, fairly well preserved Viking Group sections from wells in local depressions in the North Viking Graben Area. The results show the presence of high relative amounts of bisnorhopane in the “Syn-rift sections”, whilst the “Post-rift sections” contain little or no bisnorhopane. Since most exploration wells are drilled on structural highs, primarily penetrating the “Post-rift Draupne”, this may explain why many analyzed source rock sections in this area contain little bisnorhopane.As a correlation of Draupne sections using the vertical, relative bisnorhopane distributions, it is suggested to be a potential stratigraphic marker for the area, indicating the presence of “Syn-rift Draupne” sediments.The relative bisnorhopane amounts follow a logarithmic reduction with depth and thermal maturity. The bisnorhopane signal is nearly extinguished at 3700 m depth at a maturity of Ro = 0.9–1.0%. 相似文献
167.
Mancheol Suh Min-Ho Koo Suck-Won Choi Insun Song 《Geotechnical and Geological Engineering》2004,22(2):269-283
In order to consider a counterplan to preserve an ancient royal tomb in Kongju, Korea, the deformation of the wall structure,
the atmospheric temperature in the tomb, and the groundwater level have been monitored. The long-term measurement of biaxial
tilting of the tomb walls revealed that the brick-built subsurface opening had been subjected to severe structural instability.
The measured deformation of the tomb was consistent with the displacement of soil around the tomb calculated using a numerical
analysis. The instability of the tomb structure is closely related to the rainy season as the deformations measured are several
times that in the dry season. A sudden change of temperature inside the tomb exerted an influence on the deformation of the
tomb structure as well. It is suggested that the excavation be restored for tourists, the quicklime layer for preventing groundwater
infiltration is reinforced, and a constant temperature is kept inside the tomb.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
168.
Fusion of multispectral and panchromatic Satellite images using the curvelet transform 总被引:18,自引:0,他引:18
Myungjin Choi Rae Young Kim Myeong-Ryong Nam Hong Oh Kim 《Geoscience and Remote Sensing Letters, IEEE》2005,2(2):136-140
A useful technique in various applications of remote sensing involves the fusion of different types of satellite images, namely multispectral (MS) satellite images with a high spectral and low spatial resolution and panchromatic (Pan) satellite image with a low spectral and high spatial resolution. Recent studies show that wavelet-based image fusion provides high-quality spectral content in fused images. However, the results of most wavelet-based methods of image fusion have a spatial resolution that is less than that obtained via the Brovey, intensity-hue-saturation, and principal components analysis methods of image fusion. We introduce an improved method of image fusion which is based on the amelioration de la resolution spatiale par injection de structures (ARSIS) concept using the curvelet transform, because the curvelet transform represents edges better than wavelets. Because edges are fundamental in image representation, enhancing the edges is an effective means of enhancing spatial resolution. Curvelet-based image fusion has been used to merge a Landsat Enhanced Thematic Mapper Plus Pan and MS image. The proposed method simultaneously provides richer information in the spatial and spectral domains. 相似文献
169.
Origin of Mesozoic gold mineralization in South Korea 总被引:6,自引:0,他引:6
Abstract The Mesozoic gold–silver deposits in South Korea are closely associated with the Mesozoic granitoids. The Jurassic gold–silver deposits can be distinguished from the Cretaceous ones in terms of occurrence, alteration style, gold fineness, associated mineral assemblage, fluid inclusion and stable isotopic compositions. The Jurassic deposits were formed in mesozonal environments related to deep-seated granitoids, whereas the Cretaceous ones were formed in epizonal environments related to shallow-level granitoids. The Jurassic auriferous deposits (about 165–145 Ma) show fluid characteristics typical of an orogenic-type gold deposit, and were probably generated in a compressional regime caused by an orthogonal convergence of the Izanagi oceanic plate into the Asiatic margin. However, strike-slip faults and caldera-related fractures, together with subvolcanic to volcanic activity, may have played an important role in the formation of Cretaceous gold–silver lode deposits (about 110–45 Ma) under a continental arc setting. 相似文献
170.
Hydrochemistry of urban groundwater in Seoul, South Korea: effects of land-use and pollutant recharge 总被引:1,自引:0,他引:1
Byoung-Young Choi Seong-Taek Yun Soon-Young Yu Pyeong-Koo Lee Seong-Sook Park Gi-Tak Chae Bernhard Mayer 《Environmental Geology》2005,48(8):979-990
The ionic and isotopic compositions (δD, δ18O, and 3H) of urban groundwaters have been monitored in Seoul to examine the water quality in relation to land-use. High tritium contents
(6.1–12.0 TU) and the absence of spatial/seasonal change of O–H isotope data indicate that groundwaters are well mixed within
aquifers with recently recharged waters of high contamination susceptibility. Statistical analyses show a spatial variation
of major ions in relation to land-use type. The major ion concentrations tend to increase with anthropogenic contamination,
due to the local pollutants recharge. The TDS concentration appears to be a useful contamination indicator, as it generally
increases by the order of forested green zone (average 151 mg/l), agricultural area, residential area, traffic area, and industrialized
area (average 585 mg/l). With the increased anthropogenic contamination, the groundwater chemistry changes from a Ca–HCO3 type toward a Ca–Cl(+NO3) type. The source and behavior of major ions are discussed and the hydrochemical backgrounds are proposed as the basis of
a groundwater management plan. 相似文献