p-mode Oscillations of α Cen A     

A. Thoul  R. Scuflaire  B. Vatovez  A. Noels  P. Magain  M. Briquet  M.-A. Dupret 《Astrophysics and Space Science》2003,284(1):241-244

Models of Cen A & B have been computed using the masses determinedby Pourbaix et al. (2002) and the data derived from the spectroscopicanalysis of Neuforge and Magain (1997). The seismological dataobtained by Bouchy and Carrier (2001, 2002) do help improveour knowledge of the evolutionary status of the system. All the constraintsare satisfied with a model which gives an age of about 6 Gyr for the binary.  相似文献   

Measuring the flow resistance of submerged grass     

C. A. M. E. Wilson  M. S. Horritt 《水文研究》2002,16(13):2589-2598

Through laboratory experiments conducted in a grass‐lined flume, the hydraulic resistance of grass is measured and quantified. For the grass examined, it is found that Manning's n value is greater than those recommended in well‐established texts such as Chow (1959. Open Channel Flow. McGraw‐Hill: Singapore), relatively lower than those predicted by n‐UR methods, but corresponds well with the value found from calibration studies of two‐ and three‐dimensional numerical models. The assumption of a uniform Manning's n value with flow depth, which is often made in numerical modelling, may be invalid depending on the relative submergence of the vegetation. Drag coefficients are evaluated for a method applicable to three‐dimensional numerical models. Further detailed experimental investigation and application of these approaches within a numerical modelling framework is now recommended. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Structural style of the Chos Malal fold and thrust belt,Neuquén basin,Argentina: Relationship between thick- and thin-skinned tectonics     

《Journal of South American Earth Sciences》2015

The Chos Malal fold and thrust belt (FTB) is a thick-skinned mountain belt formed by Mesozoic deposits of the Neuquén Basin during the Andean orogeny. Four structural cross-sections in the entire deformed area, supported by field and subsurface data, suggest a strong link between thick and thin-skinned structures. Major Andean thrusts branching from a detachment placed 12 km into the crust created large basement wedges, which were inserted in the cover producing minor order structures. The westernmost of these wedges is exposed forming the Cordillera del Viento, while others basement slices at depth were interpreted from seismic lines. These thick-skinned structures transferred deformation to the cover along the Auquilco Formation and contributed to create all thin-skinned structures surveyed in the Chos Malal FTB. We recognized half-graben geometries in the seismic lines, preserving their extensional configuration, which suggests that the main normal faults were not inverted. Shortenings calculated from the restoration of the four cross-sections are 16.9 km (29.7%), 16.9 km (29.7%), 14.7 km (26.9%) and 14.15 km (26.3%), which evidence a slight diminution of the contraction toward the south probably associated with the plunge of the Cordillera del Viento structure in this segment of the Chos Malal FTB.  相似文献   

δ34S isotope values of dissolved sulfate (SO4 2−) as a tracer for battery acid (H2SO4) contamination in groundwater     

Thomas Pichler 《Environmental Geology》2005,47(2):215-224

The application of sulfur isotope (³⁴S) values of sulfate in groundwater provided the information necessary to evaluate the source, transport and fate of battery acid and associated contaminants at the Gulf Coast Recycling (GCR) facility. The chemical and isotopic composition of groundwater beneath the (GCR) property, a battery recycling facility in east Tampa, Florida, varies more than expected for an area of comparable size. Sulfate (SO₄^2–) values, for example, range from 1.2 to 11,500 mg/L and oxygen and hydrogen isotopes do not attenuate towards the weighted annual mean. Those samples that are high in sulfate generally have a low pH, which immediately indicates battery acid (H₂SO₄) contamination as a potential source for the sulfate. The low pH and high reactivity of the sulfuric acid groundwater cause the formation of hydrogeological microenvironments due to preferential dissolution of carbonate minerals, which in turn causes enhanced recharge and groundwater flow in certain areas; thus, the extreme scatter in the data set. Because of the difficult hydrogeology it is not straightforward to delineate the point-sources of contamination and up to five potential scenarios have to be evaluated: (1) seawater intrusion, (2) upwelling of high-sulfate groundwater, (3) local dissolution of gypsum, (4) an up-gradient contaminant source to the northeast of the GCR property and (5) battery acid contamination.  相似文献   

A simplified method for simulation of strong ground motion using finite rupture model of the earthquake source     

A.?JoshiEmail author  S.?Midorikawa 《Journal of Seismology》2004,8(4):467-484

We present a simplified method to simulate strong ground motion for a realistic representation of a finite earthquake source burried in a layered earth. This method is based on the stochastic simulation method of Boore (Boore, D. M., 1983, Bull. Seism. Soc. Am. 73, 1865–1894) and the Empirical Greens Function (EFG) method of Irikura (Irikura, K., 1986, Proceedings of the 7th Japan Earthquake symposium, pp. 151–156). The rupture responsible for an earthquake is represented by several subfaults. The geometry of subfaults and their number is decided by the similarity relationships. For simulation of ground motion using the stochastic simulation technique we used the shapping window based on the kinetic source model of the rupture plane. The shaping window deepens on the geometry of the earthquake source and the propagation characteristics of the energy released by various subfaults. The division of large fault into small subfaults and the method for accounting their contribution at the surface is identical to the EGF. The shapping window has been modified to take into account the effect of the transmission of energy released form the finite fault at various boundaries of the layered earth model above the source. In the present method we have applied the correction factor to adjust slip time function of small and large earthquakes. The correction factor is used to simulate strong motion records having basic spectral shape of ² source model in broad frequency range. To test this method we have used the strong motion data of the Geiyo earthquake of 24th March 2001, Japan recorded by KiK network. The source of this earthquake is modelled by a simple rectangular rupture of size 24 × 15 km, burried at a depth of 31 km in a multilayered earth model. This rupture plane is divided into 16 rectangular subfaults of size 6.0 × 3.75 km each. Strong motion records at eight selected near-field stations were simulated and compared with the observed records in terms of the acceleration and velocity records and their response spectrum. The comparison confirms the suitability of proposed rupture model responsible for this earthquake and the efficacy of the approach in predicting the strong motion scenario of earthquakes in the subduction zone. Using the same rupture model of the Geiyo earthquake, we compared the simulated records from our and the EGF techniques at one near-field station. The comparison shows that this technique gives records which matches in a wide frequency range and that too from simple and easily accessible parameters of burried rupture.  相似文献   

SPATIAL AND THERMAL CHARACTERISTICS OF MOUNTAIN PERMAFROST,NORTHWEST CANADA     

ANTONI G. LEWKOWICZ  PHILIP P. BONNAVENTURE  SHARON L. SMITH  ZOÉ KUNTZ 《Geografiska Annaler: Series A, Physical Geography》2012,94(2):195-213

  相似文献   

Courtroom Ethnography: Researching the Intersection of Law,Space, and Everyday Practices     

《The Professional geographer》2012,64(1):131-138

This article argues for a more sustained use of courtroom ethnography by geographers as a means to research legal phenomena, especially in matters of court trials. To do this, I begin by referencing two main threads of courtroom ethnographies conducted in disciplines outside geography, specifically the spaces of the courthouse and courtrooms and the study of emotion and bodily performances by sociolegal and sociology scholars. To then underscore the ways in which a geographical perspective can enhance this existing research and point to topical and theoretical interventions that courtroom ethnography might offer geography, I draw on my experiences with courtroom ethnography on the criminal trial against former Enron chief executives Ken Lay and Jeffrey Skilling. This experience produced a nuanced and lively understanding of how law, justice, and space comingle through the court’s physical spaces and performative embodiments. My conclusions emphasize courtroom ethnographies’ scholarly opportunities for researchers who study the intersection of law and space, while also reflecting on its challenges. Key Words: corporation, courtroom, Enron, ethnography, legal geography.  相似文献   

Satellite and ground observations for large-scale air pollution transport in the Yellow Sea region     

Hak-Sung Kim  Yong-Seung Chung 《Journal of Atmospheric Chemistry》2008,60(2):103-116

Large-scale air pollution transport (LSAPT) in the Yellow Sea region and their inflow onto the Korean Peninsula were observed through satellite images and ground measurements. LSAPT includes regional continental air-masses saturated with pollutants originating from China and subsequently landing on or passing through the Korean Peninsula. It is also possible to identify the distribution and transport patterns of LSAPT over the Yellow Sea. The ground concentrations for PM10, PM2.5 and CO measured at Cheongwon, located in the centre of south Korea, were compared with NOAA satellite images. Notably, the episodes observed of the LSAPT show a PM2.5 to PM10 ratio of 74% of the daily maximum concentrations. However, cases of duststorms were clearly distinguished by much higher PM10 concentrations and a ratio of 30% of PM2.5 to PM10 for daily maximum concentrations. For the episode on January 27, 2006, the inflow of a regionally polluted continental air-mass into the central and southwestern regions of the Korean Peninsula was observed sequentially at various ground observatories as well as by satellite. The north airflow dissipated the clouds over Mt. Halla on Jeju Island and further downwind, reducing air pollution and creating a von Kármán vortex.  相似文献   

Effect of pedogenesis on the stable isotopic composition of calcretes and n‐alkanes: Implications for palaeoenvironmental reconstruction     

Vijayananda Sarangi  Anurag Kumar  Prasanta Sanyal 《Sedimentology》2019,66(5):1560-1579

In a fluvial system, depending on sub‐aerial exposure, non‐pedogenic pond calcretes can be modified into pedogenic calcretes. The present study attempts to understand the effect of sub‐aerial exposure and pedogenesis on calcretes using carbon and oxygen isotopic composition. For this purpose, two profiles (profile‐A and profile‐B) from the same stratigraphic level in Rayka from the western part of India were selected. The profiles are separated by a distance of 500 m and showed differences in calcrete characteristics. In profile‐A, the calcretes showed pedogenic features (root traces and void filling spar) whereas calcretes in profile‐B showed non‐pedogenic characteristics (fine laminations). However, some of the calcretes in profile‐A exhibited remnants of fine laminations suggesting that initially the calcretes had a non‐pedogenic origin but were modified due to pedogenesis. In profile‐A, the carbon and oxygen isotope values of pedogenic calcrete (δ¹³C_PC and δ¹⁸O_PC) showed more variation compared with non‐pedogenic pond calcretes (δ¹³C_SPC and δ¹⁸O_SPC) in profile‐B. The δ¹³C_PC and δ¹³C_SPC values exhibited a spread of 3·0‰ and 1·3‰, respectively, and δ¹⁸O_PC and δ¹⁸O_SPC values showed a spread of 2·3‰ and 1·3‰, respectively. The differences in the isotopic composition between the two profiles suggest that pedogenesis controlled the isotopic inheritance in calcretes. In addition, the carbon isotopic composition of organic matter (δ¹³C_OM) and n‐alkanes (δ¹³C_n‐alk) that forms the basis of palaeovegetational reconstruction have also been measured to understand the effect of pedogenesis on organic matter in both of the profiles. The average δ¹³C_OM values in profile‐A and profile‐B are ?23·4‰ and ?21·1‰, respectively. The disparity in δ¹³C_OM values is a result of the difference in the sources and preservation of organic matter. However, the δ¹³C_n‐alk values show a similar trend in profile‐A and profile‐B, indicating that sources of n‐alkanes are the same in both of the profiles and δ¹³C_n‐alk values are unaffected by the pedogenic modifications.  相似文献   

Biomarker hydrogen isotope composition (δD) as proxy for Holocene hydroclimatic change and seismic activity in SW Peloponnese,Greece          下载免费PDF全文

Elin Norström  Christos Katrantsiotis  Martin Finné  Jan Risberg  Rienk H. Smittenberg  Stefan Bjursäter 《第四纪科学杂志》2018,33(5):563-574

  相似文献