Browsing by Author "Kumar, Dinesh"

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    Ambient noise levels due to dawn chorus at different habitats in Delhi. Environment and We: An
    (2011) Singh, Manoj; Kumar, Dinesh; Pandey, Puneeta; Kumar, Krishan; Jain, Vinod Kumar
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    Spatio – temporal variations of urban heat island over Delhi
    (Elsevier, 2014) Pandey, Alok Kumar; Singh, Sachchidanand; Berwal,Shivesh; Kumar, Dinesh; Pandey, Puneeta; Prakash,Amit; Lodhi, Neelesh; Maithani,Sandeep; Jain,Vinod Kumar; Kumar, Krishan
    Temporal and spatial trends of the surface urban heat island (UHI) formation over Delhi are examined with respect to aerosol load and land-cover variations. The study reveals that temperatures over Delhi are higher than those over the surrounding regions almost through-out the year during the night time. The nocturnal heat island intensity is minimum (0–2 K) during the monsoon months and maximum during the month of March (4–6 K). The UHI trends during the day-time are however, significantly different. It is observed that a day-time cool island forms over Delhi twice during the year in the months of May–June and October–December. Analysis of temporal variations in urban heat island intensity (UHII) and aerosol load over Delhi reveals a significant negative correlation between UHII and aerosol optical depth (AOD). Spatial analysis of LST, land-cover and AOD for the months of March, May and November confirms the significant role of AOD along with land-cover variables such as percentage area under the classes built-up, rock, vegetation and bare soil. Comparative analysis of LST in the regions lying north, south, east and west of Delhi in relation to the prevailing land-cover suggests that thermal inertia is also a very important factor determining the urban-rural thermal structure.
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    Structural and Dielectric Behaviour of Blend Polymer Electrolyte based on PEO-PAN + LiPF6
    (The Research Publication, 2016) Arya, Anil; Sharma, Sweety; Sharma, A. L.; Kumar, Dinesh; Sadiq, Mohd.
    Solid polymer electrolytes (SPEs) have recently gained more research interest in the area of materials science due to their wide application range in energy storage/conversion devices like batteries, supercapacitors, solar cells and sensors. A blend polymer electrolyte based on polyethyeleneoxide (PEO) and polyacrylonitrile (PAN) doped with Lithium Hexaflurophosphate (LiPF6) has been prepared by solution casting technique using Dimethyalformamide (DMF) as a solvent. The complex formation has been studied using X-ray diffraction (XRD). The decrease in intensity and broadness in peak revels the amorphous phase formation. The dielectric study of PS films has been done which gives the two order decrement in relaxation time (i.e. 10-4- 10-6) which is directly related to faster ion dynamics in polymer electrolytes. The analysis has shown the dielectric polarization at low frequencies. The dielectric peak has been observed to shift toward the higher frequency side with the addition of salt, suggesting the low sample viscosity and faster conduction of ions.