Influence of aerosol on clouds over the Indo-Gangetic Plain, India     

D. M. Lal  S. D. Patil  H. N. Singh  Sachin D. Ghude  S. Tiwari  Manoj K. Srivastava 《Climate Dynamics》2013,41(3-4):601-612

Using Total Ozone Mapping Spectrometer Aerosol Index (AI) and NCEP/NCAR reanalysis clouds data for the period 1979–1992, the influence of aerosol on the clouds (low and high cloud cover) over the Indo-Gangetic Plain (IGP) in India has been brought out for the first time in the present study. AI shows increasing tendency over the IGP suggesting that aerosol loading over this region increased significantly during the study period. In our analysis, High Cloud Cover (HCC) shows increasing trend and Low Cloud Cover (LCC) shows decreasing trend over the IGP during the same period. During pre-monsoon season when aerosol loading is more, HCC increases in positive correlation with AI. On the other hand, LCC show decreasing trend and is anti-correlated with AI. During summer monsoon, aerosol shows increasing trend but their effect on HCC and LCC is not seen to be significant. Similarly, the role of humidity on aerosol induced changes in HCC and LCC over the IGP region was also analyzed. In the low to moderate humid areas of IGP region (western and middle IGP), increasing AI leads to increase in HCC and decrease in LCC. On the other hand, in high humid areas (eastern IGP), increase in AI does not show any significant effect on HCC, but LCC shows positive trend. Therefore, we strongly argue that increasing aerosol loading enhances Cloud Condensation Nuclei over the region which in turn, alters the microphysical properties of clouds by reducing the size of cloud droplets, and atmospheric humidity controls the aerosol effect on clouds. During the recent period (2005–2010), similar features have also been observed over the IGP region.  相似文献   

Neuro-fuzzy based approach for wave transmission prediction of horizontally interlaced multilayer moored floating pipe breakwater     

S.G. Patil  S. Mandal 《Ocean Engineering》2011,38(1):186-196

The ocean wave system in nature is very complicated and physical model studies on floating breakwaters are expensive and time consuming. Till now, there has not been available a simple mathematical model to predict the wave transmission through floating breakwaters by considering all the boundary conditions. This is due to complexity and vagueness associated with many of the governing variables and their effects on the performance of breakwater. In the present paper, Adaptive Neuro-Fuzzy Inference System (ANFIS), an implementation of a representative fuzzy inference system using a back-propagation neural network-like structure, with limited mathematical representation of the system, is developed. An ANFIS is trained on the data set obtained from experimental wave transmission of horizontally interlaced multilayer moored floating pipe breakwater using regular wave flume at Marine Structure Laboratory, National Institute of Technology Karnataka, Surathkal, India. Computer simulations conducted on this data shows the effectiveness of the approach in terms of statistical measures, such as correlation coefficient, root-mean-square error and scatter index. Influence of input parameters is assessed using the principal component analysis. Also results of ANFIS models are compared with that of artificial neural network models.  相似文献   

A numerical study of mineral alteration and self-sealing efficiency of a caprock for CO2 geological storage     

Hailong Tian  Tianfu Xu  Fugang Wang  Vivek V. Patil  Yuan Sun  Gaofan Yue 《Acta Geotechnica》2014,9(1):87-100

Geochemical interactions of brine–rock–gas have a significant impact on the stability and integrity of the caprock for long-term CO₂ geological storage. Invasion of CO₂ into the caprock from the storage reservoir by (1) molecular diffusion of dissolved CO₂, (2) CO₂-water two-phase flow after capillary breakthrough, and (3) CO₂ flow through existing open fractures may alter the mineralogy, porosity, and mechanical strength of the caprock due to the mineral dissolution or precipitation. This determines the self-enhancement or self-sealing efficiency of the caprock. In this paper, two types of caprock, a clay-rich shale and a mudstone, are considered for the modeling analyses of the self-sealing and self-enhancement phenomena. The clay-rich shale taken from the Jianghan Basin of China is used as the base-case model. The results are compared with a mudstone caprock which is compositionally very different than the clay-rich shale. We focus on mineral alterations induced by the invasion of CO₂, feedback on medium properties such as porosity, and the self-sealing efficiency of the caprock. A number of sensitivity simulations are performed using the multiphase reactive transport code TOUGHREACT to identify the major minerals that have an impact on the caprock’s self-sealing efficiency. Our model results indicate that under the same hydrogeological conditions, the mudstone is more suitable to be used as a caprock. The sealing distances are barely different in the two types of caprock, both being about 0.6 m far from the interface between the reservoir and caprock. However, the times of occurrence of sealing are considerably different. For the mudstone model, the self-sealing occurs at the beginning of simulation, while for the clay-rich shale model, the porosity begins to decline only after 100 years. At the bottom of the clay-rich shale column, the porosity declines to 0.034, while that of mudstone declines to 0.02. The sensitive minerals in the clay-rich shale model are calcite, magnesite, and smectite-Ca. Anhydrite and illite provide Ca²⁺ and Mg²⁺ to the sensitive minerals for their precipitation. The mudstone model simulation is divided into three stages. There are different governing minerals in different stages, and the effect of the reservoir formation water on the alteration of sensitive minerals is significant.  相似文献   

Site-specific pre-evaluation of bioremediation technologies for chloroethene degradation     

S. S. Patil  E. M. Adetutu  P. J. Sheppard  P. Morrison  I. R. Menz  A. S. Ball 《International Journal of Environmental Science and Technology》2014,11(7):1869-1880

Groundwater systems are important sources of water for drinking and irrigation purposes. Unfortunately, human activities have led to widespread groundwater contamination by chlorinated compounds such as tetrachloroethene (PCE). Chloroethenes are extremely harmful to humans and the environment due to their carcinogenic properties. Therefore, this study investigated the potential for bioremediating PCE-contaminated groundwater using laboratory-based biostimulation (BS) and biostimulation–bioaugmentation (BS-BA) assays. This was carried out on groundwater samples obtained from a PCE-contaminated site which had been unsuccessfully treated using chemical oxidation. BS resulted in complete dechlorination by week 21 compared to controls which had only 30 % PCE degradation. BS also led to a approximately threefold increase in 16S rRNA gene copies compared to the controls. However, the major bacterial dechlorinating group, Dehalococcoides (Dhc), was undetectable in PCE-contaminated groundwater. This suggested that dechlorination in BS samples was due to indigenous non-Dhc dechlorinators. Application of the BS-BA strategy with Dhc as the augmenting organism resulted in complete dechlorination by week 17 with approximately twofold to threefold increase in 16S rRNA and Dhc gene abundance. Live/dead cell counts (LDCC) showed 70–80 % viability in both treatments indicating active growth of potential dechlorinators. The LDCC was strongly correlated with cell copy numbers (r > 0.95) suggesting its potential use for low-cost monitoring of bioremediation. This study also shows the dechlorinating potential of indigenous non-Dhc groups can be successfully exploited for PCE decontamination while demonstrating the applicability of microbiological and chemical methodologies for preliminary site assessments prior to field-based studies.  相似文献   

Stability of slopes in a fire-prone mine in Jharia Coalfield, India   总被引：2，自引：0，他引：2  

T. N. Singh  S. P. Pradhan  V. Vishal 《Arabian Journal of Geosciences》2013,6(2):419-427

Stability of slope in an opencast mine is always associated with safety and economics. The steeper slope is always preferred from economic point of view but prone to failure, whereas flatter slopes are uneconomical. A proper understanding of slope which will be a steep enough to be stable is required for safety, economy, and stability of men and machineries. The Rajapur opencast mine is one of the important mines in terms of good quality coal but has problems of water seepage, fire, and weak overburden materials. The existing coal mine has three working seams which are mostly thick and occur at shallow depths of about 50–60 m. Overall slope angle of the working faces as well as final pit is very steep which leads to failures. In the present paper, an attempt has been made to characterize the materials of the mine for simulation of existing slopes. The rock samples from the coal measures were collected to determine the petrophysical characteristics of various rock units. All the pertinent geological parameters from the exposed face were also collected during field visit to assess the slope mass rating (SMR). A two-dimensional finite difference tool was employed to simulate the existing slope geometry as well as relevant parameters of the rock units. The numerical simulation indicates various vulnerable points which are prone to failure as well as displacements at various points along the slope. The results of simulations are corroborated with the SMR value. The results are well matching with the field condition.  相似文献   

Study of microflares through soxs mission     

Rajmal Jain  Vishal Joshi  Yoichiro Hanaoka  T. Sakurai  Nipa Upadhyay 《Journal of Astrophysics and Astronomy》2006,27(2-3):339-346

We present a study of 10 microflares observed in 4–30 keV by SOXS mission simultaneously with Hα observations made at NAOJ, Japan during the interval between February and August 2004. The X-ray and Hα light curves showed that the lifetime of microflares varies between 4 and 25 min. We found that the X-ray emission in all microflares under study in the dynamic energy range of 4–30 keV can be fitted by thermal plus non-thermal components. The thermal spectrum appeared to start from almost 4 keV, low level discriminator (LLD) of both Si and CZT detectors, however it ends below 8 keV. We also observed the Fe line complex features at 6.7 keV in some microflares and attempted to fit this line by isothermal temperature assumption. The temperature of isothermal plasma of microflares varies in the range between 8.6 and 10.1 MK while emission measure between 0.5 and 2x10⁴9 cm^-3. Non-thermal (NT) emission appeared in the energy range 7–15 keV with exponent -6.8 ≤γ≤-4.8. Our study of microflares that had occurred on 25 February 2004 showed that sometimes a given active region produces recurrent microflare activity of a similar nature. We concluded from X-ray and simultaneous Hα observations that the microflares are perhaps the result of the interaction of low lying loops. It appears that the electrons that accelerated during reconnection heat the ambient coronal plasma as well as interact with material while moving down along the loops and thereby produce Hα bright kernels.  相似文献   

X-ray cavities and temperature jumps in the environment of the strong cool core cluster Abell 2390     

S. S. Sonkamble  N. D. Vagshette  P. K. Pawar  M. K. Patil 《Astrophysics and Space Science》2015,357(2):1-18

  相似文献   

Observations of Plasma Blobs by OI 630 nm Using ASI and Photometer over Kolhapur,India     

D. P. Nade  A. K. Sharma  S. S. Nikte  G. A. Chavan  R. N. Ghodpage  P. T. Patil  S. Gurubaran 《Earth, Moon, and Planets》2014,112(1-4):89-101

This paper presents observations of plasma blobs by nightglow OI 630.0 nm emissions using ground-based techniques, all sky imager and photometer from Kolhapur. The nightglow observations have been made at low latitude station, Kolhapur (16.42°N, 74.2°E, and 10.6°N dip lat.) during clear moonless nights for period of October 2011–April 2012. Generally, these occur 3 h after sunset (18:00 IST). Herein we have calculated velocities of plasma blobs using scanning method, introduced by Pimenta et al. (Adv Space Res 27:1219–1224, 2001). The average zonal drift velocity (eastward) of the plasma blobs were found to be 133 ms^?1 and vary between 100 and 200 ms^?1. The width (east–west expansion) and length (north–south expansion) of plasma blobs is calculated by recently developed method of Sharma et al. (Curr Sci 106(08):1085–1093, 2014b). Their mean width and length were in the range of 70–180 and 500–950 km respectively. The study shows that localized eastward polarization electric field plays an important role in the generation of plasma blobs.  相似文献   

The Fe-Line Feature in the X-Ray Spectrum of Solar Flares: First Results from the SOXS Mission     

Rajmal Jain  Anil K. Pradhan  Vishal Joshi  K. J. Shah  Jayshree J. Trivedi  S. L. Kayasth  Vishal M. Shah  M. R. Deshpande 《Solar physics》2006,239(1-2):217-237

We present the first results from the low-energy detector payload of the solar X-ray spectrometer (SOXS) mission, which was launched onboard the GSAT-2 Indian spacecraft on May 08, 2003 by the GSLV-D2 rocket to study solar flares. The SOXS low-energy detector (SLD) payload was designed, developed, and fabricated by the Physical Research Laboratory (PRL) in collaboration with the Space Application Centre (SAC), Ahmedabad and the Indian Space Research Organization (ISRO) Satellite Centre (ISAC), Bangalore. The SLD payload employs state-of-the-art, solid-state detectors, viz., Si PIN and Cadmium-Zinc-Telluride (CZT) devices that operate at near room temperature (−20 ^°C). The energy ranges of the Si PIN and CZT detectors are 4 – 25 and 4 – 56 keV, respectively. The Si PIN provides sub-keV energy resolution, while the CZT provides ~1.7 keV energy resolution throughout the energy range. The high sensitivity and sub-keV energy resolution of the Si PIN detector allows measuring the intensity, peak energy, and the equivalent width of the Fe-line complex at approximately 6.7 keV, as a function of time in all ten M-class flares studied in this investigation. The peak energy (E _p) of the Fe-line feature varies between 6.4 and 6.7 keV with increase in temperature from 9 to 58 MK. We found that the equivalent width (w) of the Fe-line feature increases exponentially with temperature up to 30 MK and then increases very slowly up to 40 MK. It remains between 3.5 and 4 keV in the temperature range of 30 – 45 MK. We compare our measurements of w with calculations made earlier by various investigators and propose that these measurements may improve theoretical models. We interpret the variation of both E _p and w with temperature as being to the changes in the ionization and recombination conditions in the plasma during the flare, and as a consequence, the contribution from different ionic emission lines also varies.  相似文献   

Data acquisition, control, communication and computation system of solar X-ray spectrometer (SOXS) mission     

Amish B. Shah  N. M. Vadher  Rajmal Jain  Hemant Dave  Vishal Shah  K. S. B. Manian  Satish Kayasth  Vinod Patel  Girish Ubale  Kirit Shah  Chirag Solanki  M. R. Deshpande  Ramkrishna Sharma  C. N. Umapathy  N. Viswanath  Ravi Kulkarni  P. S. Kumar 《Journal of Astrophysics and Astronomy》2006,27(2-3):299-304

The Solar X-ray Spectrometer (SOXS) mission onboard GSAT-2 Indian Spacecraft was launched on 08 May 2003 using GSLV-D2 rocket by Indian Space Research Organization (ISRO). SOXS aims to study solar flares, which are the most violent and energetic phenomena in the solar system, in the energy range of 4–56 keV with high spectral and temporal resolution. SOXS employs state-of-the-art semiconductor devices, viz., Si-Pin and CZT detectors to achieve sub-keV energy resolution requirements. In this paper, we present an overview of data acquisition, control, communication and computation of low energy payload of the SOXS mission.  相似文献