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1.
Natural Hazards - Slope failures are recurrent phenomena during the Indian Summer Monsoon (ISM) season in the mountainous regions of Arunachal Himalaya, NE India, with a consequent damaging impact... 相似文献
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The photocatalytic activity of combustion synthesized nanocrystalline CeAlO3 was determined for the degradation of four anionic and four cationic dyes. The perovskite oxide showed high‐photocatalytic activity and a complete degradation of all the dyes was possible within 2 h. The photocatalytic activity of the compound was comparable with the activity of the commercial Degussa P‐25 TiO2 catalyst. The degradation of dyes was found to follow first order kinetics and the first order degradation rate constants were determined. 相似文献
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Parag Seal 《Astrophysics and Space Science》1985,113(2):391-404
From IRAS (Infrared Astronomical Satellite) Circulars Nos. 4 to 15, 110 infrared sources have been identified. Out of these 110 identified sources 99 are galaxies, nine are nebulae, one is a dark object, and one is a non-stellar object. Thirty-five of these galaxies, have already been studied, mostly are spiral type. The characteristics of sixty-four remaining galaxies, for which the type is not known or uncertain, are studied by compairing their colours and luminosities with known galaxies. The galaxies observed by IRAS are mostly active galaxies. 相似文献
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Parag Seal 《Astrophysics and Space Science》1997,254(1):85-96
The physical parameters of both the components of fifteen symbiotic stars have been estimated statistically. Data obtained
are compared with data available in the literature from photometric and spectroscopic observations. It is found that the mass-radius
relations for close binary systems can be applicable for the giant and accreting main-sequence components of symbiotic binaries.
Amass-radius relation for the white dwarf components is derived from the linear variation of masses and radii data obtained
from observation. These statistical relations can be used to get a rough estimate of masses and radii of the components of
symbiotic stars.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Parag Seal 《Astrophysics and Space Science》1995,234(2):223-232
Far infrared IRAS measurements and near infrared observational data of nineteen faint symbiotic stars are presented in this paper. From their flux distributions and the near infrared and far infrared colours an attempt is made to study the type of these stars. The colour temperature, dust temperature and mass-loss rates are estimated from the far infrared flux ratios and compared to those of known S and D type symbiotic stars. Probably nine of them are S type, two of them are D type and three of them are D type symbiotic stars. But it is difficult to suggest the type of five stars from the information available. 相似文献
7.
The behaviour of dense astrophysical systems can be described by the magnetohydrodynamic equations involving gravitational potential. In this paper the magnetohydrodynamic equations are solved in the wave form and a general dispersion relation have been obtained. This dispersion relation has been used with simplifying assumptions, plausible for special regions of the system and results obtained have been shown to be able to interpret the property of the gas in those special regions. For example, a region at a large distance from the centre of the system — i.e.,r — is considered. The analysis indicates that instability exists at such a large distance though it is assumed that the region is homogeneous. This explains the formation of corona, envelope of supergiant or galactic halo. 相似文献
8.
Nayan Jyoti Khound Parag Phukon Krishna G. Bhattacharyya 《Journal of the Geological Society of India》2013,82(2):162-168
The lower Jia Bharali catchment and adjoining areas in central part of North Brahmaputra Plain (NBP) is characterized by more than 800m thick Older and Younger Alluvium deposited by the west flowing Brahmaputra river and the south flowing trans Himalayan rivers. Unconfined, shallow alluvial aquifers of the area with a general southward flow are largely tapped for domestic use through numerous dug well attached with almost every household. Monitoring of 180 dug wells for two hydrological years show strong seasonal fluctuation of the groundwater table linked to the summer monsoon that brings more than 1500mm precipitation in the area between June-September. This study has presents the first ever systematic database on toxic trace elements viz., As, Cr, Fe, Mn, Ni, Pb and Zn from the shallow aquifers in north Brahmaputra plain based on water samples from 50 monitoring wells collected in both dry and wet seasons. The data was analysed with respect to WHO standards for drinking water and significantly, 2 % of the measurements show As in excess of the WHO limit while 60% of the samples in the wet season and as much as 90 % of the same in dry season have Cr content more than the WHO permissible limit. Pb concentration is above permissible limit of 0.05 mg/L in most of the dry season samples although 88 % of the rainy season samples show Pb concentration exceeding this limit. 34 % of the samples in the wet seasons and 86 % of the samples in the dry seasons have Mn above the permissible limit of 0.1 mg/L while in case of Ni, 56 % of the aquifers in the wet season and 72 % of the aquifers in the dry season show Ni content above the permissible limit of 0.02 mg/L. Zn contents of the aquifers are however very low throughout the year. 相似文献
9.
Sameer Saran Kapil Oberai Parag Wate Amol Konde Arnab Dutta Kavisha Kumar A. Senthil Kumar 《Journal of the Indian Society of Remote Sensing》2018,46(6):957-972
Virtual 3D city models are increasingly being used to model the realms of the real world for utilization in a number of applications related to environmental simulations including, urban planning, mapping the energy characteristics of buildings, noise mapping, flood modelling, etc. Apart from geometric and appearance/textural information, these applications have a requirement for complex urban semantics. Currently, a number of 3D standards are available in CAD, BIM and GIS related domains for the storage, visualization and transfer of 3D geospatial datasets. Initially, the 3D data models (such as COLLADA, VRML, X3D, etc.) were purely graphical/geometrical in nature and mainly used for visualization purposes. With the inclusion of thematic modules in OGC CityGML, the integration of geometry and semantics in a single data model paved the way for better sharing of virtual 3D city models. In spite of the availability of a wide range of 3D data standards, there are certain differences with respect to geometry, topology, semantics, LODs, etc., which complicates the integration of 3D geodata from heterogeneous sources. This paper serves to highlights the need for the innovative solutions with respect to the urban environmental related simulations primarily based on the use of virtual 3D city models. Four use cases are studied in this context namely, (1) urban solar potential estimation using CityGML models, (2) simulation of traffic noise level mapped on building walls from the urban road segments, (3) CityGML based 3D data models interoperability, and (4) 3D indoor logistics and subsurface utilities. However, for modelling majority of use cases, CityGML does not provide explicit thematic representations but provides support for extending the CityGML schema using Application Domain Extensions. In a nutshell, the study explores the semantic modelling capabilities of the CityGML for the transformation of native 3D virtual city models to one satisfying capabilities like semantic information and support towards interoperability. 相似文献
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With the advent of energy rating systems and increased energy efficiency requirements for built environment, the assessment of energy performance of new buildings and refurbishment rates of existing buildings have become an important compliance in the building design process. In order to analyse and simulate the effects of energy-efficient measures for buildings, it is essential to establish spatio-semantic information interoperability between the building design and energy modelling softwares. Data interoperability facilitates different domains to interact with the single building model. The geometrical properties of building semantics such as effective areas exposed to total incident radiation were used as indicators for assessment of seasonal solar potential of buildings. The key urban solar potential indicators were identified based on the semantic components of buildings. The CityGML instance document derived from a proposed energy application domain extension (ADE) conceptual schema could be used as common interoperable model for both the design and energy simulation systems. 相似文献