Current Science

Arup Roy Chowdhury ¹, Manish Saxena ¹, Ankush Kumar ¹, S. R. Joshi ¹, Amitabh ¹, Aditya Dagar ¹, Manish Mittal ¹, Shweta Kirkire ¹, Jalshri Desai ¹, Dhrupesh Shah ¹, J. C. Karelia ¹, Anand Kumar ¹, Kailash Jha ¹, Prasanta Das ¹, H. V. Bhagat ¹, Jitendra Sharma ¹, D. N. Ghonia ¹, Meghal Desai ¹, Gaurav Bansal ¹, Ashutosh Gupta ¹

Affiliations
1 Space Applications Centre, Indian Space Research Organisation, Ahmedabad 380 015, IN

Abstract

Orbiter High Resolution Camera (OHRC) onboard Chandrayaan-2 Orbiter-craft, is a very high spatial resolution camera operating in visible panchromatic band. OHRC’s primary goal is to image the landingsite region prior to landing for characterization and finding hazard-free zones. Post landing operation of the OHRC will be for scientific studies of small-scale features on the lunar surface. OHRC makes use of the time delay integration detector to have good signal-tonoise ratio under low illumination condition and less integration time due to very high spatial resolution. Ground sampling distance (GSD) and swath of OHRC (in nadir view) are 0.25 m and 3 km respectively, from 100 km altitude. GSD is better than 0.32 m in oblique view (25° pitch angle) during landing site imaging from 100 km altitude in two stereo views in consecutive orbits. This article includes the details of the configuration, sub-systems, imaging modes, and optical, spectral and radiometric characterization performance.

Keywords

Ground Sampling Distance, Orbiter High Resolution Camera, Relative Spectral Response, Square Wave Response, Time Delay Integration.

Full Text

   

Henry John Noltie ¹, Anand Kumar ², Kumar Avinash Bharati ², Avishek Bhattacharjee ², Gopal Krishna ²

Affiliations
1 Royal Botanic Garden Edinburgh, Edinburgh EH3 5LR, GB
2 Central National Herbarium, Botanical Survey of India, Howrah 711 103, IN

Abstract

Sixty-one herbarium specimens collected by William Roxburgh (1751–1815) from India have recently been discovered in the Central National Herbarium (CAL), Howrah. A catalogue is provided here, including annotations of original names and determinations, currently accepted names and notes on actual or potential type status. The specimens came to CAL from eight different sources, and notes are provided on their possible origins.

Keywords

Annotations, Catalogue, Herbarium Specimens, Sources And Origins, Sub-collections.

Full Text

   

Anand Kumar ¹, Pusker Singh ¹, Sanjay Kumar Sharma ¹, Nawal Kishore ¹, C. S. Singh ¹

Affiliations
1 Department of Mining Engineering, Indian Institute of Technology (BHU), Varanasi 221 005, IN

Abstract

Blast-induced ground vibration (BIGV) velocities and frequencies are of major concern due to their adverse effects and damage to structures. Therefore, it becomes essential to assess the velocities and frequencies induced by blasting in terms of quantitative and qualitative assessment to overcome the problems. There is a need for scientific studies using devices like triaxial geophone associated with a seismograph to measure the peak particle velocity (PPV) and dominant frequency which cause damage to domestic or residential structures near an opencast mine. Each mine has specific geo-mining conditions, and scientific studies provide appropriate results. In total, 32 number of blasting data sets were recorded at every 50 m from the blast site to the last observation point near the village. Ground vibration associated damage criteria is defined in terms of the PPV at different frequency levels and the strength of the structures under study. The permissible limits of BIGV has been provided by the Directorate General of Mines Safety, Dhanbad, India. The permissible PPV values of the BIGV in India is 2, 5, 10 for the historical and sensitive structures, 5, 10, 15 for domestic houses and 10, 20, 25 for industrial buildings at 25 Hz dominant excitation frequencies respectively. The recorded dataset has been proposed through standard models. The velocity amplitude versus frequency gives a reliable relationship about damage criteria of structures. The structures were analysed vis-à-vis PPV and dominant frequency to correlate the damage possibility. The present study carried out in a mega opencast project provides the basic knowledge to assess the safe distance from blasting site for specific charge of explosive, waves which are responsible for more damage to nearby structures and to determine the correlation coefficient between measured and predicted PPV values.

Keywords

Frequency, Ground Vibration, Opencast Mine, Peak Particle Velocity, Structural Response.

Full Text