An effective medium inversion algorithm for gas hydrate quantification and its application to laboratory and borehole measurements of gas hydrate-bearing sediments   总被引：1，自引：0，他引：1  

Shyam Chand  Tim A. Minshull  Jeff A. Priest  Angus I. Best  Christopher R. I. Clayton  William F. Waite 《Geophysical Journal International》2006,166(2):543-552

  相似文献   

Effect of Nickel and Cadmium on Ammonium Uptake Kinetics of Free and Immobilized Cells of Anacystis nidulans     

Mamta Awasthi  Lal Chand Rai 《洁净——土壤、空气、水》2004,32(2):149-153

The stress effect of Ni and Cd on the ammonium uptake varied significantly (ANOVA test) in free and immobilized state of the test organism. The effect due to the interaction between different variables (cell state type, metal type and metal dose) was studied to depict the significant or non‐significant variation in the ammonium uptake by free and immobilized cells in the presence of metal ions. Ammonium uptake exhibited a competitive mode of inhibition in the presence of Ni in both free and immobilized state of the organism. However, Cd exhibited non‐competitive and competitive inhibition in free and immobilized cells, respectively. The study demonstrates that there is a considerable influence of metal ions on the ammonium uptake. Cd was found to be more toxic compared to Ni in both free and immobilized state.  相似文献   

Elastic velocity models for gas-hydrate-bearing sediments—a comparison     

Shyam Chand  Tim A. Minshull  Davide Gei  José M. Carcione 《Geophysical Journal International》2004,159(2):573-590

  相似文献   

Some geoelectrical investigations for potential groundwater zones in part of Azamgarh area of U.P.     

C. L. Singh  Shyam N. Singh 《Pure and Applied Geophysics》1970,82(1):270-285

Summary The results of some electrical sounding measurements have been used for defining potential groundwater zones in part of Azamgarh district of Uttar Pradesh, India. The area covered is a part of gangetic alluvial tract. Aquifers consist of lenticular sand masses distributed within the alluvium. The ideal geoelectrical conditions, generally desired for the interpretation of resistivity curves, lack in the area. Among the number of layers encountered in lithologs, only a few are delineated by quantitative interpretation of the sounding data. A study of the total transverse resistance and longitudinal conductance for a particular depth of the alluvial column has helped in defining potential groundwater zones.  相似文献   

Relation between spring water radon anomalies and seismic activity in Garhwal Himalaya     

Rakesh Chand Ramola 《Acta Geophysica》2010,58(5):814-827

The variations of spring water radon concentration and meteorological parameters were analysed in relation to the seismic activities in Garhwal Himalaya, India. The radon anomalies were classified on the basis of statistical treatment of the daily observations. The precise measurements of water discharge rate from the spring have been made along with radon measurements for earthquake precursory study. The earthquakes with epicentral distances less than 150 km were considered by an empirical relationship. Pre-, co-, and post-seismic changes in the radon concentration were taken carefully into account in the empirical relationship to establish this behaviour as a potential earthquake precursor. The empirical relationship has been validated by the radon data recorded from the spring waters. The magnitudes of the earthquakes were estimated by using the empirical relationship by introducing computed correlation coefficient of radon and meteorological parameters. The calculated magnitude of some local earthquakes matches exactly with the magnitude recorded by the laboratory seismograph. The possible mechanisms that may cause a radon anomaly are also discussed.  相似文献   

Adsorption of Cadmium Ions from Aqueous Solution Using Granular Activated Carbon and Activated Clay     

Kailas L. Wasewar  Pradeep Kumar  Shri Chand  Bina N. Padmini  Tjoon Tow Teng 《洁净——土壤、空气、水》2010,38(7):649-656

The present study was aimed at removing cadmium ions from aqueous solution through batch studies using adsorbents, such as, granular activated carbon (GAC) and activated clay (A‐clay). GAC was of commercial grade where as the A‐clay was prepared by acid treatment of clay with 1 mol/L of H₂SO₄. Bulk densities of A‐clay and GAC were 1132 and 599 kg/m³, respectively. The surface areas were 358 m²/g for GAC and 90 m²/g for A‐clay. The adsorption studies were carried out to optimize the process parameters, such as, pH, adsorbent dosage, and contact time. The results obtained were analyzed for kinetics and adsorption isotherm studies. The pH value was optimized at pH 6 giving maximum Cd removal of 84 and 75.2% with GAC and A‐clay, respectively. The adsorbent dosage was optimized and was found to be 5 g/L for GAC and 10 g/L for A‐clay. Batch adsorption studies were carried out with initial adsorbate (Cd) concentration of 100 mg/L and adsorbent dosage of 10 g/L at pH 6. The optimum contact time was found to be 5 h for both the adsorbents. Kinetic studies showed Cd removal a pseudo second order process. The isotherm studies revealed Langmuir isotherm to better fit the data than Freundlich isotherm.  相似文献   

A site‐consistent method to quantify sufficiency of alternative IMs in relation to PSDA          下载免费PDF全文

Somayajulu L. N. Dhulipala  Adrian Rodriguez‐Marek  Shyam Ranganathan  Madeleine M. Flint 《地震工程与结构动力学》2018,47(2):377-396

In probabilistic seismic demand analysis, evaluation of the sufficiency of an intensity measure (IM) is an important criterion to avoid biased assessment of the demand hazard. However, there exists no metric to quantify the degree of sufficiency as per the criterion of Luco and Cornell (2007). This paper proposes a site‐specific unified measure for degree of sufficiency from all seismological parameters under consideration using a total information gain metric. This unified metric for sufficiency supports not only comparison of the performance of different IMs given a response quantity but also assessment of the performance of a particular IM across different response quantities. The proposed sufficiency metric was evaluated for a 4‐story steel moment frame building, and the influence of ground motion selection on the degree of sufficiency was investigated. It was observed that ground motion selection can have a significant impact on IM sufficiency. Because computing the total information gain requires continuous deaggregation across the IM space, an approximate deaggregation technique that allows for a more practical estimation of marginal deaggregation probabilities is proposed. It is expected that the total information gain metric proposed in this paper will aid in understanding the efficiency‐sufficiency relation, thus enabling the selection of a proper scalar IM for a given site and application in probabilistic seismic demand analysis.  相似文献   

Gas hydrate stability zone modelling in areas of salt tectonics and pockmarks of the Barents Sea suggests an active hydrocarbon venting system     

S. Chand  J. Mienert  K. Andreassen  J. Knies  L. Plassen  B. Fotland 《Marine and Petroleum Geology》2008,25(7):625-636

The Barents Sea seabed exhibits an area of major glacial erosion exposing parts of the old hydrocarbon basins. In this region, we modelled the gas hydrate stability field in a 3D perspective, including the effects of higher order hydrocarbon gases. We used 3D seismic data to analyse the linkage between fluid-flow expressions and hydrate occurrences above old sedimentary basin systems and vertical faults. Pockmarks showed a relation to fault systems where some of them are directly connected to hydrocarbon bearing sedimentary formations. The influence of bottom water temperature, pore water salinity and geothermal gradient variation on gas hydrate stability zone (GHSZ) thickness is critically analysed in relation to both geological formations and salt tectonics. Our analysis suggests a highly variable GHSZ in the Barents Sea region controlled by local variations in the parameters of stability conditions. Recovery of gas-hydrate sample from the region and presence of gas-enhanced reflections below estimated BSR depths may indicate a prevalent gas-hydrate stable condition.  相似文献   

Factors responsible for driving the glaciation in the Sarchu Plain,eastern Zanskar Himalaya,during the late Quaternary          下载免费PDF全文

Shubhra Sharma  Pritam Chand  Pinky Bisht  Anil D. Shukla  S. K. Bartarya  Y. P. Sundriyal  Navin Juyal 《第四纪科学杂志》2016,31(5):495-511

  相似文献   

Evaluation and modelling of Tertiary source rocks in the central Arctic Ocean     

Ute Mann  Jochen Knies  Shyam Chand  Wilfried Jokat  Ruediger Stein  Janine Zweigel   《Marine and Petroleum Geology》2009,26(8):1624-1639

With the recently recovered organic-rich sediments of early Tertiary age from the Lomonosov Ridge by the Integrated Ocean Drilling Program (IODP) Expedition 302, the first data collection directly from source rocks of the central basins of the Arctic Ocean is now available. Using the results of seismic interpretations and published sedimentological and organic geochemical data from Expedition 302, the framework for the first quantitative assessment of source-rock quality and distribution of the Palaeogene sediments was modelled in the central Arctic Ocean. The modelling results suggest that an approximately 100-m-thick Early to Middle Eocene sedimentary sequence of good to very good source rocks exists along a 75 km long transect across the Lomonosov Ridge. In-situ generation of hydrocarbons is unlikely because the overburden (200–250 m) and consequently the thermal maturity are too low. Burial history and thermal modelling reveal that an additional overburden of at least 1000 m is necessary to start hydrocarbon generation along the ridge. However, source-rock modelling results show that good source-rock potential may exist in correlative units in the adjacent Amundsen Basin. Simulated organic carbon contents of 1.5–5%, coupled with an overburden of 1000–1200 m, and heat flow anomalies (117 and 100 mW m⁻²) due to the vicinity to the Gakkel Ridge spreading centre indicate that necessary conditions for hydrocarbon expulsion are already reached, and point to viability of a potential petroleum system. Our results support the hypothesis that deposition of a potentially good hydrocarbon source rock occurred across the entire Arctic Basin and adjacent margins during the early Tertiary.  相似文献