NOPR Collection:

Development of 20 kW amplifier at very high frequency (VHF)

2004-08-01T00:00:00Z

Title: Development of 20 kW amplifier at very high frequency (VHF) Authors: Singh, Raghuraj; Srinivas, Y S S; Khilar, Pankaj; Kadia, B; Dani, Sunil; Bora, Dhiraj; Bhattacharya, D S Abstract: A triode based 20 kW cw (continuous wave) amplifier has been developed and tested indigenously at 91.2 MHz and 70 MHz. The equipment will drive the pre-driver stage of 200 kW, which will, in turn drive the final stage of 1.5 MW of rf power to heat plasma in SST-1 Tokamak for 1000 s. Various aspects of design and fabrication of the amplifier are discussed in this paper. Page(s): 267-277

Some observations on the characteristics of aerosols at traffic junctions in Pune city

2004-08-01T00:00:00Z

Title: Some observations on the characteristics of aerosols at traffic junctions in Pune city Authors: Safai, P D; Rao, P S; Momin, G A; Ali, K; Chate, D M; Praveen, P S Abstract: Vehicular emissions are one of the potential sources of air pollution, especially in the urban regions. Pune, one of the rapidly growing cities of India, faces a severe threat from this problem. Observations of Total Suspended Particulates (TSP) and Aitken Nuclei (AN) were conducted at four traffic junctions in the city during summer (May 2000) and winter (Jan-Feb 2001). Concentrations of TSP were very high at all the traffic junctions and also the number density of AN was very high. Concentrations of all the measured constituents were more, except NH₄ and Cu, at traffic junctions than those reported at Pashan, a semi-rural location, comparatively away from vehicular effects. Page(s): 260-266

Association of aerosol optical depth with near surface aerosol properties in urban environment

2004-08-01T00:00:00Z

Title: Association of aerosol optical depth with near surface aerosol properties in urban environment Authors: Latha, K Madhavi; Badarinath, K V S Abstract: Changes of near surface aerosol properties and their association with aerosol optical depth studied over tropical urban environment in Hyderabad during January-May, 2003 corresponding to winter and summer seasons have been presented. Aerosol Optical Depth (AOD) has been studied using MICROTOPS-II sunphotometer and aerosol size distribution has been studied using Quartz Crystal Microbalance Particle analyzer. Results from the study suggest that the temporal variation of near surface sub-micron aerosol mass concentration and columnar aerosol optical depth at 500 nm are well correlated. Aerosol size index as well as Angstrom wavelength exponent has been found to be high during February, indicating relative dominance accumulation mode particles. During summer season Angstrom exponent values have been found to be low indicating relative dominance of coarse mode particles. Page(s): 256-259

A logistic regression model for prediction of premonsoon convective development over Kolkata

2004-08-01T00:00:00Z

Title: A logistic regression model for prediction of premonsoon convective development over Kolkata Authors: Dasgupta, S; De, U K Abstract: Certain parameters (both dynamic and thermodynamic) have been identified as significant for the occurrence of convective developments in the premonsoon period (March-May) in Kolkata (India). In the present paper, an attempt has been made to develop a logistic regression model for prediction of the risk of occurrence of these convective developments from a knowledge of the values of significant parameters. The model was developed on the basis of a sample of 87 days covering the premonsoon period of the year 1990. When used for the purpose of validation on the basis of data of an arbitrarily chosen year, it yielded about 80% correct predictions. Page(s): 252-255