Radar Observations of Leonid Meteor Shower 2003     

Devulapalli Venkata Phani Kumar  Kammadhanam Chenna Reddy  Ganji Yellaiah 《Astrophysics and Space Science》2006,306(4):235-239

Observations carried out during Leonid meteor shower 2003, by using Indian MST radar (13.46^N, 79.18^E; dip 12.5^N) are used to determine the number density of meteoroids through the cross section of the meteor streams. Cross sections are calculated for a number of classes of echo duration (particle size). They are also used to determine the relative flux of the shower in particle size ranges producing radar meteor echoes having durations <0.4 s, 0.4–1 s and >1 s. Mean activity profiles along the Earth's passage through the stream show a systematic change of the peak activity and the width of the stream depending on the distribution of echo durations across the stream. The patterns of mass distribution index s are presented and discussed.  相似文献   

Developing Basic Design and Mathematical Framework for a Mobile Mapping System—a Case Study Using Available Sensors     

Manohar Yadav  Salil Goel  A. K. Singh  Bharat Lohani 《Journal of the Indian Society of Remote Sensing》2014,42(2):301-310

There is a growing demand for technologies that support capturing of comprehensive and good quality 3D spatial data at a faster rate with low investment and minimal effort, while also causing least disturbance to other activities in the area. Mobile mapping systems (MMS), which are being developed in a few western countries, solve this problem but their import is highly expensive. While the components of a MMS are easily available off-the-shelf at lower cost, the main reason for their high cost is the intellectual property involved in the sensor design, integration, calibration, and the related software. Developing the intellectual property locally can bring down the cost of MMS to a large extent. Keeping this in mind, a MMS has been developed in this research using the locally available sensors. This paper describes the methodology to integrate navigation and mapping sensors including the developed calibration procedures. It further describes the time synchronization technique developed for multi-sensor data fusion and algorithms implemented by software package for data processing. The sensors integrated in the MMS include a standard GPS, IMU and a standard laser scanner. A Kalman filter is implemented to integrate the GPS and IMU data, which provides position and orientation information for the sensors. A simulation software package is also developed to verify, understand and develop the equations used in MMS. Field tests have been performed using the developed MMS and the results are shown for a few cases. Results validate the designed algorithms and indicate the successful development of the MMS, which has potential to be further developed and used in field. Though a number of papers are available on MMS, the thrust of this paper is to present a complete methodology for developing a MMS using locally available sensors. Unlike available papers, this paper outlines all aspects of design, calibration and operation, where each of these aspects is handled in a novel way as demanded by the available sensors. This is particularly useful for individuals or organizations interested in procuring sensor components off-the-shelf and develop their own (low cost) Mobile Mapping system.  相似文献   

Soil erosion assessment in Rangit catchment,India through a process-based model in the geospatial environment     

Hari Venkata Durga Rao Korada  Venkateshwar Rao Vala 《国际地球制图》2013,28(5):507-519

The accurate assessment of soil erosion in the spatial environment can give valuable input in designing reservoirs and for preparing watershed management action plans. Rangit River in northeastern India is affected by severe soil erosion, causing reduction in its reservoir capacity. The main aim of the paper is to estimate the soil erosion in the Rangit catchment, India through a process-based soil erosion model that integrates remote sensing and field data in the geospatial domain, and also to identify the problem areas for further watershed management action plans. Various topographic parameters that were derived from land use, soil texture and a digital elevation model were used for the estimation of soil erosion. The Morgan, Morgan and Finny model was used to compute soil erosion. Based on the drainage pattern, the catchment was divided into eight sub-catchments for detailed study. Annual soil erosion was estimated for four years from 2002 to 2005 using the corresponding year’s meteorological data. Estimated soil erosion was compared with the field data in each year and found very good correlation.  相似文献   

‘Thermohaline front’ off the east coast of India and its generating mechanism     

Panangattu Viswanathan Hareesh Kumar  Basil Mathew  Madathiparambil Ranganatha Ramesh Kumar  Akula Raghunadha Rao  Puvvala Surya Venkata Jagadeesh  Kalarickal Gopalan Radhakrishnan  Thiyyadi Nandakumar Shyni 《Ocean Dynamics》2013,63(11-12):1175-1180

Physical oceanography measurements reveal a strong salinity (0.18 psu km^?1) and temperature (0.07 °C km^?1) front off the east coast of India in December 1997. T–S diagrams suggest lateral mixing between the fresh water at the coast and the ambient warmer, saltier water. This front seems to be the result of southward advection of fresh and cool water, formed in the northern Bay of Bengal during the monsoon, by the East Indian Coastal Current, as suggested by the large-scale salinity structure in the SODA re-analysis and the anti-cyclonic gyre in the northwestern Bay of Bengal during winter. The data further reveals an offshore front in January, which appears to be the result of a meso-scale re-circulation around an eddy, bringing cold and freshwater from the northern Bay of Bengal further away from the shore. Our cruise data hence illustrates that very strong salinity fronts can appear in the Bay of Bengal after the monsoon, as a result of intense coastal circulation and stirring by eddies.  相似文献   

Assessing the impact of various wind forcing on INCOIS-GODAS simulated ocean currents in the equatorial Indian Ocean     

Sanikommu Sivareddy  Muthalagu Ravichandran  Madathil Sivasankaran Girishkumar  Koneru Venkata Siva Rama Prasad 《Ocean Dynamics》2015,65(9-10):1235-1247

  相似文献   

Evaluation of atmospheric corrections on hyperspectral data with special reference to mineral mapping   总被引：1，自引：0，他引：1  

Nisha Rani  Venkata Ravibabu Mandla  Tejpal Singh 《地学前缘(英文版)》2017,8(4):797-808

Hyperspectral images have wide applications in the fields of geology, mineral exploration, agriculture, forestry and environmental studies etc. due to their narrow band width with numerous channels. However, these images commonly suffer from atmospheric effects, thereby limiting their use. In such a situation, atmospheric correction becomes a necessary pre-requisite for any further processing and accurate interpretation of spectra of different surface materials/objects. In the present study, two very advance atmospheric approaches i.e. QUAC and FLAASH have been applied on the hyperspectral remote sensing imagery. The spectra of vegetation, man-made structure and different minerals from the Gadag area of Karnataka, were extracted from the raw image and also from the QUAC and FLAASH corrected images. These spectra were compared among themselves and also with the existing USGS and JHU spectral library. FLAASH is rigorous atmospheric algorithm and requires various parameters to perform but it has capability to compensate the effects of atmospheric absorption. These absorption curves in any spectra play an important role in identification of the compositions. Therefore, the presence of unwanted absorption features can lead to wrong interpretation and identification of mineral composition. FLAASH also has an advantage of spectral polishing which provides smooth spectral curves which helps in accurate identification of composition of minerals. Therefore, this study recommends that FLAASH is better than QUAC for atmospheric correction and correct interpretation and identification of composition of any object or minerals.  相似文献   

Sinkhole subsidence due to mining   总被引：2，自引：2，他引：2  

Kalendra B. Singh  Bharat B. Dhar 《Geotechnical and Geological Engineering》1997,15(4):327-341

This paper reviews the modes of formation of sinkhole subsidence associated with mining activities, drawing on examples in India. Sinkhole (pot-hole) subsidence is an abrupt local depression at the surface which can be hazardous to life and property due to its tendency to occur without warning. Shallow extraction, weak overburden and geological discontinuities are the main factors which cause them. Sinkholes occur due to the failure of a mine roof which migrates through the overlying strata until the failure zone intercepts the unconsolidated overburden. Alternatively they may occur by the creation of cavities in the overburden following the inflow of sand and soil from the overlying weathered and friable strata through faults. Overburden cavities eventually cave in and sinkholes appear at the surface. Sinkholing phenomena can be controlled to some extent by proper design of mining supports and construction of walls to create a barrier around an area prone to sinkholes in bord and pillar workings. Backfilling and grouting can be used to stabilize abandoned underground workings.  相似文献   

Non-Conventional Energy Sources: A Geo-Spatial Study of Site,Situation, Production and Economy of Wind Farms in Satara District     

Bharat M. Sule 《Journal of the Geological Society of India》2018,92(1):107-110

Wind energy is a popular from the non-conventional energy sources in the World. In India states like Tamil Nadu, Gujarat, Orissa, and Maharashtra are as regarded as superior areas with respect to this type energy. The installed capacity of wind in India till December 2010 was 13,056.37 MW, principally distributed throughout the Maharashtra, Tamil Nadu, Rajasthan, Karnataka, Andhra Pradesh, Gujarat, Kerala, Madhya Pradesh, West Bengal, etc. In Maharashtra, there are 38 wind farms and the 3655 wind machines are installed with the 3431.86MW capacity of power generation up to September 2013. In Satara district, 17 wind sites and also other some sites are discovered. At present there are 1636 wind turbines are installed with its capacity of power generation is 1122.61MW and the production of wind energy of 2183745.15KWh average per annum in Satara district.The main objectives of the present paper are to assess the scope of non-conventional energy resources especially the power generation from wind and to analyze the trend and distribution of the wind mills and wind farms in Satara district. It is find out the amount of recovered from the power generation comes around 12 years without subsidy and around 8 years with subsidy. The total life span of wind turbines is 25 years. It is very much clean and does not cause any problem to the environment as well as to the survival on the surface of the earth. Therefore, it is inferred that the generation of power from wind is not only cheaper and permanent energy source but also a non-polluting, freely available source. It is helpful for the development of economically and socially in a region especially in rural development. With these consequences the income level will increase and it will further help in minimising the social disparities.  相似文献   

Development and comparison of aerial photograph aided visualization pipelines for LiDAR datasets     

Suddhasheel Ghosh  Bharat Lohani 《International Journal of Digital Earth》2015,8(8):656-677

Light Detection and Ranging (LiDAR) technology generates dense and precise three-dimensional datasets in the form of point clouds. Conventional methods of mapping with airborne LiDAR datasets deal with the process of classification or feature specific segmentation. These processes have been observed to be time-consuming and unfit to handle in scenarios where topographic information is required in a small amount of time. Thus there is a requirement of developing methods which process the data and reconstruct the scene in a small amount of time. This paper presents several pipelines for visualizing LiDAR datasets without going through classification and compares them using statistical methods to rank these processes in the order of depth and feature perception. To make the comparison more meaningful, a manually classified and computer-aided design (CAD) reconstructed dataset is also included in the list of compared methods. Results show that a heuristic-based method, previously developed by the authors perform almost equivalent to the manually classified and reconstructed dataset, for the purposes of visualization. This paper makes some distinct contributions as: (1) gives a heuristics-based visualization pipeline for LiDAR datasets, and (2) presents an experimental design supported by statistical analysis to compare different pipelines.  相似文献   

Intraseasonal variability of subsurface ocean temperature anomalies in the Indian Ocean during the summer monsoon season     

Konda  Gopinadh  Gulakaram  Venkata Sai  Vissa  Naresh Krishna 《Ocean Dynamics》2023,73(3-4):165-179

Ocean Dynamics - The present study focuses on the variability of subsurface ocean temperature and associated planetary waves (oceanic Kelvin and Rossby waves) in the Indian Ocean during the boreal...  相似文献