On the Inclusion of Some Biological Impacts and Influences in Coupled Transport Phenomena in Unsaturated Soil     

Hywel Rhys Thomas  Suresh Channarayapatna Seetharam  Philip James Vardon 《Geotechnical and Geological Engineering》2011,29(2):181-191

This paper presents a first attempt at the inclusion of some biological impacts and influences in the authors’ continued research on coupled transport phenomena through unsaturated porous media. The work presented here forms an extension to an existing coupled Thermo-Hydraulic-Chemical–Mechanical Model (THCM) to include the biological aspects, as a first attempt towards a new THCMB framework. The biological model incorporates biodegradation kinetics of organic substrates and resultant effects in the inorganic geochemistry. In order to achieve this, the biological aspects of the model are coupled to an equilibrium geochemical model following a two-step partial equilibrium approach. Additionally, of concern in contaminant/pollutant transport studies, including the biological aspects, is the effect on human health. This paper therefore also presents some aspects of a health impact analysis model adopted in this study.  相似文献   

Numerical Modeling and Spatial Moment Analysis of Thermal Fronts in a Coupled Fracture-Skin-Matrix System     

N.?NatarajanEmail author  G.?Suresh Kumar 《Geotechnical and Geological Engineering》2011,29(4):477-491

In this study, the behavior of thermal fronts along the fracture is studied in the presence of fracture-skin in a coupled fracture-matrix system. Cold water is injected into the fracture, which advances gradually towards production well, while extracting heat from the surrounding reservoir matrix. The heat conduction into the fracture-skin and the rock-matrix from the high permeability fracture is assumed to be one dimensional perpendicular to the axis of fluid flow along the fracture. Constant temperature cold water is injected through an injection well at the fracture inlet. The fluid flow takes place along the horizontal fracture which ensures connectivity between the injection and production wells. Since the rock-matrix is assumed to be tight, the permeability of fracture-skin as well as the rock-matrix is neglected. The present study focuses on the heat flux transfer at the fracture-skin interface as against the earlier studies on fracture-matrix interface, and the sensitivity of additional heterogeneity in the form of fracture skin in a conventional fracture-matrix coupled system is studied. The behavior of thermal fronts for various thermal conductivity values of the fracture-skin and rock-matrix is analyzed. Spatial moment analysis is performed on the thermal distribution profiles resulting from numerical studies in order to investigate the impact on mobility and dispersion behavior of the fluid in the presence of fracture-skin. The presence of fracture skin affects the heat transfer significantly in the coupled fracture-matrix system. The lower order spatial moments indicate that the effective thermal velocity increases with increase in skin thermal conductivity and a significant thermal dispersion is observed at the inlet of the fracture owing to the high thermal conductivity of the fracture-skin at the early stages. Furthermore the higher spatial moments indicate that the asymmetricity increases with decrease in skin thermal conductivity unlike the case with half fracture aperture and fluid velocity and the kurtosis is maximum with higher skin thermal conductivity which implies enhanced heat extraction from the fracture-skin into the fracture. Results suggest that the amount of heat extraction by the circulating fluid within the fracture from the reservoir not only depends on the rock-matrix module of the reservoir characteristics but also the fracture-skin characteristics of the system and subsequently influence the reservoir efficiency.  相似文献   

Determination of coronal magnetic fields from 10 to 26R ⊙ using the density compression ratios of CME-driven shocks     

A. Shanmugaraju  K. Suresh  Y.-J. Moon 《Astrophysics and Space Science》2014,351(1):67-73

Recently, the estimation of coronal magnetic field using new methods, such as standoff distance method or density compression ratio method has been reported. In the present work, we utilized the density compression ratio of CME-driven shocks for 10 events at 29 different locations in the upper solar corona (10–26R _⊙) and determined the coronal magnetic field for two different adiabatic indices (γ=4/3 and 5/3). In addition, radial dependence of shock parameters in the corona is studied. It is found that the magnetic field estimated in the above range agree with the general trend. In addition, we obtained a radial profile of magnetic field [B(R)=623R ^?1.4] in the entire upper corona (3–30R _⊙) by combining the magnetic field estimated by Kim et al. (Astrophys. J. 746:118, 2012) in the range 3–15R _⊙ and that estimated in the present study in the range (10–26R _⊙). The power-law indices are nearly in agreement with recent results of CME-driven shocks reported in the literature. The results are discussed with the comparison of newly reported coronal magnetic field values obtained by different techniques and found that the power-law relation closely follow the literature values.  相似文献   

Long-term changes in the cosmic-ray diurnal anisotropy   总被引：1，自引：0，他引：1  

A. G. Ananth  D. Venkatesan  Suresh Pillai 《Solar physics》1993,143(1):187-196

A detailed study has been conducted on the long-term changes in diurnal anisotropy of cosmic rays for the two solar cycles (20 and 21) during the period 1965–1990; this shows that the amplitude of the anisotropy is related to the characteristics of high and low amplitude days. The occurrence of high amplitude days are found to be positively correlated with the sunspot cycle while the low amplitude days are correlated negatively with the sunspot cycle. Further, the variability of the time of maximum of the aniotropy indicates that it essentially is composed of two components; one in the 1800 hours (corotation) direction and the other, an additional component in the 1500 hours direction (45° east of the S-N line) apparently caused by the reversal of the solar polar magnetic field. Our observations also suggest that the direction of the anisotropy of high- and low-amplitude days contribute significantly to the long-term behaviour of the diurnal anisotropy as it produces an additional component of cosmic rays in the radial (1200 hours) direction.  相似文献   

Remarks on the test-run output by Jain and Thompson     

Suresh Chandra 《Astrophysics and Space Science》1987,138(1):221-226

The Test-Run Output of erratum notice published by Jain and Thompson (1985) for their paper (Jain and Thompson, 1983) appears to be inconsistent. Hence, their computer programme needs a further modification.This paper was prepared while the author was a guest of the USSR Academy of Sciences at the A. F. Ioffe Physico-Technical Institute, Leningrad, U.S.S.R.  相似文献   

Digital soil mapping in a Himalayan watershed using remote sensing and terrain parameters employing artificial neural network model   总被引：2，自引：0，他引：2  

Justin George Kalambukattu  Suresh Kumar  R. Arya Raj 《Environmental Earth Sciences》2018,77(5):203

Digital soil mapping relies on field observations, laboratory measurements and remote sensing data, integrated with quantitative methods to map spatial patterns of soil properties. The study was undertaken in a hilly watershed in the Indian Himalayan region of Mandi district, Himachal Pradesh for mapping soil nutrients by employing artificial neural network (ANN), a potent data mining technique. Soil samples collected from the surface layer (0–15 cm) of 75 locations in the watershed, through grid sampling approach during the fallow period of November 2015, were preprocessed and analysed for various soil nutrients like soil organic carbon (SOC), nitrogen (N) and phosphorus (P). Spectral indices like Colouration Index, Brightness Index, Hue Index and Redness Index derived from Landsat 8 satellite data and terrain parameters such as Terrain Wetness Index, Stream Power Index and slope using CartoDEM (30 m) were used. Spectral and terrain indices sensitive to different nutrients were identified using correlation analysis and thereafter used for predictive modelling of nutrients using ANN technique by employing feed-forward neural network with backpropagation network architecture and Levenberg–Marquardt training algorithm. The prediction of SOC was obtained with an R² of 0.83 and mean squared error (MSE) of 0.05, whereas for available nitrogen, it was achieved with an R² value of 0.62 and MSE of 0.0006. The prediction accuracy for phosphorus was low, since the phosphorus content in the area was far below the normal P values of typical Indian soils and thus the R² value observed was only 0.511. The attempts to develop prediction models for available potassium (K) and clay (%) failed to give satisfactory results. The developed models were validated using independent data sets and used for mapping the spatial distribution of SOC and N in the watershed.  相似文献   

Integrated mineral magnetic and lithologic studies to delineate dynamic modes of depositional conditions in the Leh valley basin, Ladakh Himalaya, India     

S. J. Sangode  Suman Rawat  D. C. Meshram  N. R. Phadtare  N. Suresh 《Journal of the Geological Society of India》2013,82(2):107-120

We present here lithofacies and mineral magnetic results from a ～50 m thick composite record of fluvial, lacustrine and aeolian facies within the Leh valley basin of Indus River in Ladakh Himalaya. Mineral magnetic studies decipher interplay of two contrasting sediment sources viz., the unimodal ferrimagnetic source derived from Ladakh batholithic glacial domain and mixed ferri-to antiferromagnetic source derived from Indus sedimentary sequence. The lithofacies variability expresses dynamic changes in the depositional regimes controlled by base level fluctuations that are governed by the interaction of basin fill conditions and the response to Late Quaternary climatic perturbations. A three stage evolution of the Leh valley basin is proposed after comparison to other characteristic lithofacies changes within the valley as: (I) the basin under-fill conditions marked by fluvial and fluvio-lacustrine phase till ～24m (～64 Ka OSL age) above modern base level followed by (II) predominantly varved, glacio-lacustrine, basin overfill phase till 38m (～28 Ka) gradually passing into an aeolian phase; and (III) basin incision that began at the earliest Holocene warming. Advancement and retreat of glaciers from the transverse valleys, attributed to climatic oscillations, appears to have greatly controlled the basin-fill conditions in the Leh valley. The present approach demonstrates its larger scope in recording the Late Quaternary response of individual valley basins to delineate local and regional attributes of climate change in the Himalayan and Karakoram region.  相似文献   

Fluoride contamination of groundwater in parts of eastern India and a preliminary experimental study of fluoride adsorption by natural haematite iron ore and synthetic magnetite     

Suresh C. Patel  Rajiv Khalkho  Subhagya K. Patel  Janisar M. Sheikh  Duryadhan Behera  Sanjeev Chaudhari  Naraga Prabhakar 《Environmental Earth Sciences》2014,72(6):2033-2049

Incidence of high fluoride (F^?) in groundwater (>1.5 mg/L) in two tribal belts of eastern India, one around Chukru in the Palamau district of Jharkhand and the other around Karlakot in the Nuapada district of Odisha, has been studied. The maximum concentration of F^? in groundwater from dug wells and tube wells is 10.30 mg/L in Chukru and 4.62 mg/L in Karlakot. The groundwaters are mildly alkaline with pH ranges of 7.52–8.22 and 7.33–8.20 in Chukru and Karlakot, respectively. The F^? concentration is positively correlated with pH, electrical conductivity and SO₄ ^2? in both areas. The high F^? in groundwater resulted mainly from dissolution of biotite and fluorapatite in quartzofeldspathic gneiss. The ionic dominance pattern (in meq/L) is mostly in the order Ca²⁺ > Na⁺ > Mg²⁺ > K⁺ among cations and HCO₃ ^? > SO₄ ^2? > < Cl^? > F^? among anions in the Karlakot groundwater. Preliminary adsorption experiments were conducted on natural haematite iron ore and synthetic magnetite to evaluate their potential for F^? removal from water. Effects of different parameters such as contact time, pH, adsorbent dose and initial F^? concentration on the adsorption capacity of these materials were investigated. Strong dependence of F^? removal on pH was observed for both the adsorbents. With natural haematite iron ore, the maximum F^? removal of 66 % occurred at an initial pH of 3.2 for a solution with F^? concentration of 3 mg/L, adsorbent dose of 7 g/L and overnight contact time. The haematite iron ore was observed to increase the pH of the F^? solution. Adsorption equilibrium was not achieved with this adsorbent even after a contact time of 45.2 h. In the case of synthetic magnetite, 84 % F^? removal was achieved after 2 min of contact time for a solution with F^? concentration of 6 mg/L, adsorbent dose of 10 g/L and initial pH of 7. The results indicate high potential of both natural haematite iron ore and synthetic magnetite as adsorbents of F^? in water.  相似文献   

Mapping of hard rock aquifer system and artificial recharge zonation through remote sensing and GIS approach in parts of Perambalur District of Tamil Nadu,India     

A Muthamilselvan  N Rajasekaran  R Suresh 《地下水科学与工程》2014,7(3):264-281

Mapping of hard rock aquifer system and artificial recharge zonation were carried out in an area of 325 km2 in parts of the Perambalur District, Tamil Nadu, India. This district has been declared as one of the over-exploited regions in Tamil Nadu by the Central Groundwater Board. To raise the groundwater level, suitable recharge zones were identified and artificial recharge structures are suggested using geomatics technology in the present study. To this end, various thematic maps concerning lithology, soil, geomorphology, land use, land cover, slope, lineament, lineament density, drainage, drainage density and groundwater depth level were prepared. Fissile hornblende gneiss (244 km2) covered most of the study area followed by charnockites (68 km2). Structural hills and rocky pediments characterize the major geomorphological features in the targeted area, and are followed by deep moderated pediments. The area is mostly used as crop and fallow land, followed by scrub land and deciduous forest. In the study area, the slopes are predominantly very gentle (142 km2) and nearly level (66 km2) ones. Besides, Groundwater level data of 58 wells have been generated, in which the minimum and maximum depth were 3 and 28 m respectively. Integration under the GIS environment has been carried out using all the thematic layers to identify the groundwater prospect zone through the introduction of weight and rank methods. Integrated output performances were classified into very poor, poor, moderate, good and excellent categories. All these classes were further divided into two groups as suitable and non-suitable area for the selection of recharge sites. Hard rock fractures were mapped as lineaments from satellite images, and besides that, rose diagram was also generated to find out the trend of the fracture. Furthermore, fracture data of 146 numbers have been collected using Brunton compass to generate rose diagram and were correlated with the rose diagram derived from lineaments. The present study significantly brought up a few areas such as Ammapalayam, Melapuliyur, Senjeri and around Siruvachur for artificial recharge.  相似文献   

Climatic control on extreme sediment transfer from Dokriani Glacier during monsoon,Garhwal Himalaya (India)   总被引：2，自引：0，他引：2  

Amit Kumar  Akshaya Verma  Dwarika Prasad Dobhal  Manish Mehta  Kapil Kesarwani 《Journal of Earth System Science》2014,123(1):109-120

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