Stabilization of Expansive Soil with Cement Kiln Dust and RBI Grade 81 at Subgrade Level

The present research work deals with an expansive high plastic clayey soil with cement kiln dust (CKD) and stabilizer (RBI Grade 81). The physical and engineering properties of soil are plasticity, compaction, unconfined compressive strength (UCS), consolidation and California bearing ratio (CBR) of the clayey soil and clay treated with CKD and stabilizer were determined. Soil chemistry was examined before and after treatment using scanning electron microscope (SEM) and elemental dispersive spectrometer. The clay mixed with CKD, CKD and RBI Grade 81 was found that optimum contents are 10 % (CKD), 15 % CKD with 4 % RBI Grade 81, respectively. The result indicates that CKD alone will decrease maximum dry density and increase optimum moisture content. CKD with RBI Grade 81 slightly increases maximum dry density and decreases optimum moisture content. UCS increased with CKD alone and CKD with RBI Grade 81 from 88.3 to 976 kN/m², respectively. CBR values were increased by the addition of CKD, CKD with RBI Grade 81 from 1.65 to 21.7 %. With the curing time of 3, 14 and 28 days, UCS and CBR values were increased due to pozzolanic reaction from cementations material. The treated soil has considerable reduction in compression index. SEM images clearly indicate the formation of CSH and CAH gel.     

Preliminary results of the close-off depth and the stable isotopic records along a 109.91 m ice core from Dome A,Antarctica

A 109.91 m ice core was recovered from Dome A (or Dome Argus), the highest ice feature in Antarctica, during the 2004/05 austral summer by the 21st Chinese National Antarctic Research Expedition (CHINARE-21). Both methane profile along the core and firn densification model calculation suggest that the close-off depth is at about 102.0 m with an ice age about 4200 a. Stable isotopes (δ18O and δD) of the chips samples produced during each run of ice core drilling at Dome A, together with those of the other co...     

一种用于海底类型聚类的新方法

By using sonar imaging, this paper presents a new algorithm for the clustering of seabed types based on the self-organizing feature maps （SOFM） neural network. The theory as well as data processing is studied in detail. Some valuable conclusions and suggestions are given     

UV-radiation in galaxies

I review the origin of UV-radiation in galaxies of different morphological types. UV-excess in spectra of massive elliptical galaxies which have predominantly old stellar populations is traditionally explained by the contribution of low-mass stars at very late, poorly known stages of evolution—by so called ‘AGB-manqué’ stars or by the population of extended horizontal branch. However recent results from the GALEX survey of a large sample of nearby ellipticals have also demonstrated probable traces of recent star formation in a third of all ellipticals observed. In spiral galaxies extended UV-disks have been discovered by the GALEX; they are certainly illuminated by the current star formation, but what has provoked star formation in the areas of very low gas density, beyond the distribution of older stars, is a puzzle yet. The UV-spectra of starburst galaxies or starforming galactic nuclei are characterized by weak emission lines, if any, quite dissimilar to their optical spectra.     

Experimental study on the shear behavior of the interface between cushion materials and the concrete raft

Cushion is a layer of granular materials between the raft and the ground. The shear behavior of the interface between the cushion and the raft may influence the seismic performance of the superstructure. In order to quantify such influences, horizontal shear tests on the interfaces between different cushion materials and concrete raft under monotonic and cyclic loading were carried out. The vertical pressure P_v, material type and cushion thickness h_c were taken as variables. Conclusions include: 1) under monotonic loading, P_v is the most significant factor; the shear resistance P_(hmax) increases as P_v increases, but the normalized factor of resistance μ_n has an opposite tendency; 2) for the materials used in this study, μ_n varies from 0.40 to 0.70, the interface friction angle δ_s varies from 20° to 35°, while u_(max) varies from 3 mm to 15 mm; 3) under cyclic loading, the interface behavior can be abstracted as a "three-segment" back-bone curve, the main parameters include μ_n, the displacement u_1 and stiffness K_1 of the elastic stage, the displacement u_2 and stiffness K_2 of the plastic stage; 4) by observation and statistical analysis, the significance of different factors, together with values of K_1, K_2 and μ_n have been obtained.     

Spatio-temporal differentiation of landscape ecological niche in western ecological frangible region： A case study of Yan＇an region in northwestern China

In this study, we attempt to put forward a conception of landscape ecological niche, enlightened by international scholars on extending the ecological niche theory from spatial niche to functional niche. That is helpful for comprehensively appraising landscape spatial patterns and ecological functions, also, presents a new method for analyzing landscape features from multidimensional aspects. The practice process is demonstrated by taking Yan＇an region in northwestern China as a case. Firstly, the indices system including spatial attribute and functional attribute is established for assessing landscape ecological niche. Additionally, two-dimensional figures are drawn for comparing the spatio-temporal features of landscape ecological niche in 1987 and 2000 among the 13 administrative counties. The results show that from 1987 to 2000, towards Yan＇an region, spatial attribute value of landscape ecological niche changes from 1.000 to 1.178 with an obvious increment, and functional attribute value changes from 0.989 to 1.069 with a little increment, both of which enhance the regional landscape ecological niche. Towards each county, spatial attribute value of landscape ecological niche increases to different extent while functional attribute value changes dissimilarly with an increment or a decrement.     

On the nature of intraplate earthquakes

Continental intraplate regions are characterized by uniform stresses over thousands of kilometers. Local stresses, with wavelengths of tens to hundreds of kilometers can accumulate at inhomogeneities lying within these regional fields. A variety of geological structures, herein called local stress concentrators (LSCs), act as elastic inhomogeneities. The temporal buildup of stress depends on the particular structure and its geometrical relationship with the regional stress field. The interaction of the local and the regional stress fields can result in the rotation of the latter over wavelengths of tens to hundreds of kilometers. This rotation can be detected by direct measurement or from seismicity data. Intraplate earthquakes (IPEs) result when the local stresses become comparable with their regional counterparts, i.e., hundreds of megapascals. Globally, most of the seismic energy release associated with IPEs occurs within old rifts which contain LSCs most favorable for stress buildup by stress inversion. Of the various LSCs, stepover en echelon faults are associated the largest IPEs. In low tectonic strain rate regions, IPEs are associated with larger stress drops. With the availability of a variety of LSCs, there is generally an absence of repeat earthquakes. Instead, successive earthquakes occur on different structures, leading to the observation of “roaming” earthquakes. These observations suggest a need for a reevaluation of seismic hazard estimation techniques. This study addresses some of these facets of the nature of IPEs with global examples, including a unique, detailed seismicity and geodetic data set collected in a dozen years following the 2001 M 7.7 Bhuj earthquake in western India.     

Variations of trace gases over the Bay of Bengal during the summer monsoon

In situ measurements of near-surface ozone (\(\hbox {O}_{3})\), carbon monoxide (CO), and methane (\(\hbox {CH}_{4})\) were carried out over the Bay of Bengal (BoB) as a part of the Continental Tropical Convergence Zone (CTCZ) campaign during the summer monsoon season of 2009. \(\hbox {O}_{3}\), CO and \(\hbox {CH}_{4}\) mixing ratios varied in the ranges of 8–54 ppbv, 50–200 ppbv and 1.57–2.15 ppmv, respectively during 16 July–17 August 2009. The spatial distribution of mean tropospheric \(\hbox {O}_{3}\) from satellite retrievals is found to be similar to that in surface \(\hbox {O}_{3}\) observations, with higher levels over coastal and northern BoB as compared to central BoB. The comparison of in situ measurements with the Monitoring Atmospheric Composition & Climate (MACC) global reanalysis shows that MACC simulations reproduce the observations with small mean biases of 1.6 ppbv, –2.6 ppbv and 0.07 ppmv for \(\hbox {O}_{3}\), CO and \(\hbox {CH}_{4}\), respectively. The analysis of diurnal variation of \(\hbox {O}_{3}\) based on observations and the simulations from Weather Research and Forecasting coupled with Chemistry (WRF-Chem) at a stationary point over the BoB did not show a net photochemical build up during daytime. Satellite retrievals show limitations in capturing \(\hbox {CH}_{4}\) variations as measured by in situ sample analysis highlighting the need of more shipborne in situ measurements of trace gases over this region during monsoon.     

Identification of buried sinkholes using refraction tomography at Ft. Campbell Army Airfield,Kentucky

Karst aquifers are highly susceptible to contamination, with numerous points of entry for contaminants through recharge features such as sinkholes, swallow holes and solutionally enlarged fractures. These recharge features may be filled or obscured at the surface, requiring the use of geophysical or remote sensing techniques for their identification. This study uses seismic refraction data collected at the Ft. Campbell Army Airfield (CAAF), Kentucky, USA, to test the hypothesis that refraction tomography is a useful tool for imaging bedrock depressions beneath thick overburden (greater than 20 m of unconsolidated sediment). Southeast of the main taxiway of CAAF seismic velocity tomograms imaged a bedrock low, possibly a closed depression, at a depth of 25 m that had been earlier identified through delay-time analysis of the same refraction data. Tomography suggests the bedrock low is about 250-m wide by 10-m deep at its widest point. High rates of contaminant vapor extraction over the western extension of this feature suggest a high concentration of contaminants above, and within, this filled bedrock low, the base of which may contain solutionally enlarged fractures (i.e. karst conduits) that could funnel these contaminants to the upper or lower bedrock aquifers. This study thus demonstrates the viability of seismic refraction tomography as a tool for identification of filled sinkholes and bedrock depressions in karst areas.     

The role of fluids in the formation of talc deposits of Rema area,Kumaun Lesser Himalaya

Talc deposits of Rema area in the Kumaun Inner Lesser Himalaya are hosted within high magnesium carbonates of the Proterozoic Deoban Formation. These deposits occur as irregular patches or pockets mainly within magnesite bodies, along with impurities of magnesite, dolomite and clinochlore. Textures represent different phases of reactions between magnesite and silica to produce talc. Petrography, XRD and geochemistry reveal that the talc has primarily developed at the expense of magnesite and silica, leaving dolomite largely un-reacted. Early fluid inclusions in magnesite and dolomite associated with talc are filled with H₂O+NaCl+KCl ± MgCl₂ ± CaCl₂ fluids, which represent basin fluid system during diagenesis of carbonates. Their varied degree of re-equilibration was although not pervasive but points to increased burial, and hence requires careful interpretation. H₂O-CO₂ fluid with XCO₂ between 0.06 and 0.12 was equilibrated with talc formation. The reaction dolomite+quartz → talc was not extensive because T-X_CO2 was not favourable, and talc was developed principally after magnesite+quartz.