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101.
Mass loading and chemical composition of atmospheric aerosols over the Arabian Sea during the pre-monsoon months of April and May have been studied as a part of the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB). These investigations show large spatial variabilities in total aerosol mass loading as well as that of individual chemical species. The mass loading is found to vary between 3.5 and 69.2 μg m?3, with higher loadings near the eastern and northern parts of Arabian Sea, which decreases steadily to reach its minimum value in the mid Arabian Sea. The decrease in mass loading from the coast of India towards west is estimated to have a linear gradient of 1.53 μg m?3/° longitude and an e?1 scale distance of ~2300 km. SO 4 2? , Cl? and Na+ are found to be the major ionic species present. Apart from these, other dominating watersoluble components of aerosols are NO 3 ? (17%) and Ca2+ (6%). Over the marine environment of Arabian Sea, the non-sea-salt component dominates accounting to ~76% of the total aerosol mass. The spatial variations of the various ions are examined in the light of prevailing meteorological conditions and airmass back trajectories. 相似文献
102.
Zhenming Wang 《Journal of Earth System Science》2008,117(2):749
Microzonation is an effort to evaluate and map potential hazards found in an area, urban area in particular, that could be induced by strong ground shaking during an earthquake. These hazards include: ground motion amplification, liquefaction, and slope failure. The microzonation maps, depicting ground-motion amplification, liquefaction, and landslide potentials, can be produced if the ground motion on bedrock (input) and the site conditions are known. These maps, in combination with ground-motion hazard maps (on bedrock), can be used to develop a variety of hazard mitigation strategies such as seismic risk assessment, emergency response and preparedness, and land-use planning. However, these maps have certain limitations that result from the nature of regional mapping, data limitations, generalization, and computer modeling. These microzonations show that when strong ground shaking occurs, damage is more likely to occur, or be more severe, in the higher hazard areas. The zones shown on the hazard maps should not serve as a substitute for site-specific evaluations. 相似文献
103.
Alan Yong Susan E. Hough Michael J. Abrams Christopher J. Wills 《Journal of Earth System Science》2008,117(2):797
Estimation of the degree of local seismic wave amplification (site effects) requires precise information about the local site conditions. In many regions of the world, local geologic information is either sparse or is not readily available. Because of this, seismic hazard maps for countries such as Mozambique, Pakistan and Turkey are developed without consideration of site factors and, therefore, do not provide a complete assessment of future hazards. Where local geologic information is available, details on the traditional maps often lack the precision (better than 1:10,000 scale) or the level of information required for modern seismic microzonation requirements. We use high-resolution (1:50,000) satellite imagery and newly developed image analysis methods to begin addressing this problem. Our imagery, consisting of optical data and digital elevation models (DEMs), is recorded from the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) sensor system. We apply a semi-automated, object-oriented, multi-resolution feature segmentation method to identify and extract local terrain features. Then we classify the terrain types into mountain, piedmont and basin units using geomorphometry (topographic slope) as our parameter. Next, on the basis of the site classification schemes from the Wills and Silva (1998) study and the Wills et al (2000) and Wills and Clahan (2006) maps of California, we assign the local terrain units with V s 30 (the average seismic shear-wave velocity through the upper 30m of the subsurface) ranges for selected regions in Mozambique, Pakistan and Turkey. We find that the applicability of our site class assignments in each region is a good first-approximation for quantifying local site conditions and that additional work, such as the verification of the terrain’s compositional rigidity, is needed. 相似文献
104.
The coal seams of Sawang Colliery, East Bokaro Coalfields are bituminous to sub-bituminous in nature and categorized as high
gaseous seams (degree II to degree III level). These seams have the potential for coal bed methane (CBM) and their maturity
increases with increasing depth, as a result of enhanced pressure-temperature conditions in the underground. The vitrinite
maceral group composition of the investigated coal seams ranges from 62.50–83.15%, whereas the inertinite content varies from
14.93–36.81%. The liptinite content varies from 0.66% to 3.09%. The maximum micro-pores are confined within the vitrinite
group of macerals. The coal seams exhibit vitrinite reflectance values (Ro% calculated) from 0.94% (sample CG-97) to 1.21%
(sample CG-119).
Proximate analyses of the investigated coal samples reveal that the moisture content (M%) ranges from 1.28% to 2.98%, whereas, volatile matter (VM%) content is placed in the range of 27.01% to 33.86%. The ash
content (A%) ranges from 10.92% to 30.01%. Fixed carbon (FC%) content varies from 41.53% to 55.93%. Fuel ratio variation shows a restricted
range from 1.53 to 1.97. All the coal samples were found to be strongly caking and forming coke buttons.
The present study is based on the adsorption isotherm experiments carried out under controlled P-T conditions for determination of actual gas adsorption capacity of the coal seams. This analysis shows that the maximum methane
gas adsorbed in the coal sample CG-81 is 17 m3/t (Std. daf), at maximum pressure of 5.92 MPa and experimental temperature of 30°C. The calculated Langmuir regression parameters
PL and VL range from 2.49 to 3.75 MPa and 22.94 to 26.88 m3/t (Std. daf), respectively. 相似文献
105.
Singh et al (2005) examined the potential of the ANN and neuro-fuzzy systems application for the prediction of dynamic constant of rockmass.
However, the model proposed by them has some drawbacks according to fuzzy logic principles. This discussion will focus on
the main fuzzy logic principles which authors and potential readers should take into consideration. 相似文献
106.
Masyhur Irsyam Donny T. Dangkua Hendriyawan Drajat Hoedajanto Bigman M. Hutapea Engkon K. Kertapati Teddy Boen Mark D. Petersen 《Journal of Earth System Science》2008,117(2):865-878
This paper presents the development of spectral hazard maps for Sumatra and Java islands, Indonesia and microzonation study for Jakarta city. The purpose of this study is to propose a revision of the seismic hazard map in Indonesian Seismic Code SNI 03-1726-2002. Some improvements in seismic hazard analysis were implemented in the analysis by considering the recent seismic activities around Java and Sumatra. The seismic hazard analysis was carried out using 3-dimension (3-D) seismic source models (fault source model) using the latest research works regarding the tectonic setting of Sumatra and Java. Two hazard levels were analysed for representing 10% and 2% probability of exceedance (PE) in 50 years ground motions for Sumatra and Java. Peak ground acceleration contour maps for those two hazard levels and two additional macrozonation maps for 10% PE in 50 years were produced during this research. These two additional maps represent short period (0.2 s) and long-period (1.0 s) spectra values at the bedrock. Microzonation study is performed in order to obtain ground motion parameters such as acceleration, amplification factor and response spectra at the surface of Jakarta. The analyses were carried out using nonlinear approach. The results were used to develop contour of acceleration at the surface of Jakarta. Finally, the design response spectra for structural design purposes are proposed in this study. 相似文献
107.
遗迹化石在层序地层学研究中的应用 总被引:2,自引:0,他引:2
以济阳坳陷古近系沙河街组和塔里木盆地志留系为例,探讨了遗迹化石与层序地层学的关系,表现在3个方面:1)层序界面的识别层序界面位置发育有特征性的受基底控制的遗迹相,且界面上下遗迹组合类型发生变化;2)准层序界面的识别较深水环境中,界面上下生物扰动强度明显差异,界面之下扰动强度较大,扰动指数可达到3,而界面之上几乎没有生物扰动,且在同一准层序内部,由下至上,扰动强度逐渐增大;3)旋回层序的识别:在潮控滨线环境中,单个准层序内部,由下至上,高能环境的Skolithos遗迹组合逐渐变为中低能环境的Planolites-Palaeophycus遗迹组合和低能环境的Cochlichnus-Planolites遗迹组合,由下至上呈现旋回性变化特征。 相似文献
108.
Soil nails have been widely used to stabilize slopes and earth retaining structures in many countries and regions, especially, in Hong Kong. The analysis of the interaction between a soil nail and the surrounding soil is of great interests to both design engineers and researchers. In this paper, authors present a simple mathematical model for the interaction analysis of a soil nail and the surrounding soil considering a few key factors which are soil dilation, bending of the soil nail, vertical pressure, and non-linear subgrade reaction stiffness. The lateral subgrade reaction between the soil and the soil nail is assumed to obey a hyperbolic relation. Reported test data in the literature are used to verify the present model. The contributions of the soil-nail bending on the pull-out resistance are evaluated in two case studies. 相似文献
109.
110.
Maggie Cusack Yannicke Dauphin Jean-Pierre Cuif Murielle Salom Andy Freer Huabing Yin 《Chemical Geology》2008,253(3-4):172-179
Biominerals are natural composite materials comprising organic and inorganic components. Detailed knowledge of the nature and distribution of both components is a crucial requirement in order to advance our understanding of biomineral formation, their material properties and preservation potential as well as the interpretation of environmental data. Detailed chemical data are essential for our understanding of the nature and distribution of such components. Micro-XANES mapping at the sulphur K-edge reveals that, in the brachiopod Terebratulina retusa, the sulphate concentration is higher in the outer (primary) layer than in the calcite fibres of the secondary layer. This is co-incident with a higher magnesium concentration. In contrast, the sheaths surrounding the calcite fibres contain sulphur as thiol, confirming the presence of protein while, the sulphur within the fibres themselves, occurs as sulphate. Micro-XANES analysis of the insoluble organic extract from T. retusa indicates the presence of organic sulphate while Micro-Raman spectroscopy confirms that structurally substituted sulphate (SSS) is also present although semi-quantitative Raman spectroscopy carried out in this spectral region (wavenumbers 900–1200) indicates that the sulphate present is at the threshold of detection by Raman spectroscopy. The distribution of phosphorus in the shell of T. retusa correlates well with that of protein indicating the presence of phosphorylated proteins in the periostracum, the sheaths surrounding the calcite fibres and the interface between the primary and secondary layer. 相似文献