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Kumar, Praveen
- Controlled Material Transport and Multidimensional Patterning at Small Length Scales Using Electromigration
Abstract Views :259 |
PDF Views:86
Authors
Affiliations
1 Centre for Nano Science and Engineering, Indian Institute of Science, Bengaluru 560 012, IN
2 Department of Materials Engineering, Indian Institute of Science, Bengaluru 560 012, IN
1 Centre for Nano Science and Engineering, Indian Institute of Science, Bengaluru 560 012, IN
2 Department of Materials Engineering, Indian Institute of Science, Bengaluru 560 012, IN
Source
Current Science, Vol 108, No 12 (2015), Pagination: 2167-2172Abstract
Electromigration, mostly known for its damaging effects in microelectronic devices, is basically a material transport phenomenon driven by the electric field and kinetically controlled by diffusion. In this work, we show how controlled electromigration can be used to create scientifically interesting and technologically useful micro-/nano-scale patterns, which are otherwise extremely difficult to fabricate using conventional cleanroom practices, and present a few examples of such patterns. In a solid thin-film structure, electromigration is used to generate pores at preset locations for enhancing the sensitivity of a MEMS sensor. In addition to electromigration in solids, the flow instability associated with the electromigration-induced long-range flow of liquid metals is shown to form numerous structures with high surface area to volume ratio. In very thin solid films on nonconductive substrates, solidification of flow-affected region results in the formation of several features, such as nano-/micro-sized discrete metallic beads, 3D structures consisting of nanostepped stairs, etc.Keywords
Electromigration, Fabrication and Pattern Formation, Material Transport, 3D Micro-/Nano-Structures.Full Text
- Carbon Sequestration Potential of Agroforestry Systems in the Indian Arid Zone
Abstract Views :294 |
PDF Views:79
Authors
S. P. S. Tanwar
1,
Praveen Kumar
1,
Archana Verma
1,
R. K. Bhatt
1,
Akath Singh
1,
Kanhaiya Lal
1,
M. Patidar
1,
B. K. Mathur
1
Affiliations
1 ICAR-Central Arid Zone Research Institute, Jodhpur 342 003, IN
1 ICAR-Central Arid Zone Research Institute, Jodhpur 342 003, IN
Source
Current Science, Vol 117, No 12 (2019), Pagination: 2014-2022Abstract
Carbon sequestration potential of eight recommended land-use systems of arid western Rajasthan was compared. Biomass C stock was maximum in farm forestry of Acacia tortilis (31.4 Mg C ha–1) followed by Prosopis cineraria and Hardwickia binata based silvoarable systems (8.8 and 10.6 Mg C ha–1). Soil C stock was also maximum in farm forestry (47.6 Mg C ha–1) followed by Ziziphus based systems (32.5–33.9 Mg C ha–1). About 50–78% of additional soil C stock was in the form of soil inorganic carbon. The total C sequestered (biomass + soil) over a period of nineteen years was in the order: farm forestry (49.80) > silvoarable systems (11.0–13.3) > hortipasture system (8.3) > agri-horti (5.5), silvopasture (5.4) and sole pasture (5.3) compared to –1.0 Mg C ha–1 in sole cropping.Keywords
Agroforestry, Arid Zone, Carbon Sequestration, Climate Change Mitigation.Full Text
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- Subsurface Site Characterization of Donga Fan, Northwest Himalaya using Multichannel Analysis of Surface Waves and Response Analysis
Abstract Views :297 |
PDF Views:101
Authors
Affiliations
1 Wadia Institute of Himalayan Geology, 33, GMS Road, Dehradun 176 215, IN
2 Central University of Himachal Pradesh, Dharamshala 176 215, IN
1 Wadia Institute of Himalayan Geology, 33, GMS Road, Dehradun 176 215, IN
2 Central University of Himachal Pradesh, Dharamshala 176 215, IN
Source
Current Science, Vol 119, No 12 (2020), Pagination: 1948-1960Abstract
The characterization of sediments in a tectonically complex region is important from the seismological point of view to study possible earthquake effects due to the presence of soft sediments. Multichannel analysis of surface waves (MASW) method was used to acquire seismic data from 87 sites for estimating shear wave velocity (Vs) of near-surface materials beneath the Donga Fan. The majority of the Donga Fan is underlain either by alluvial fan or river terrace deposit. About 80% of the Donga Fan has an average shear wave velocity ranging from 180 to 360 m/s, whereas 20% of the area has high stiffness values (Vs ú 360 m/s). The estimated Vs values are higher in the northern part of the study area due to thin sediment (150 m) above bedrock. The response analysis suggests that peak spectral acceleration varies from 0.49 g at 1.61 Hz to 1.69 g at 3.22 Hz with variation in amplification ratio from 4 to 11 times. The spectral acceleration computed for two-storey buildings also varies from 0.10 to 0.40 g (at 5% damping), whereas in the case of singlestorey buildings it varies from 0.12 to 0.22 g (at 5% damping). The predominant frequency estimated using ambient noise measurements varies from 0.84 to 5 Hz, indicating variation in the thickness of sediments and is in good agreement with the Vs values estimated using the MASW technique.Keywords
Bedrock Response Analysis, Multichannel Analysis Of Surface Waves, Site Response, Shear Wave Velocity.Full Text
- Forest Biomass Estimation using Multi-Polarization SAR Data Coupled with Optical Data
Abstract Views :245 |
PDF Views:71
Authors
Affiliations
1 Department of Remote Sensing, BIT Mesra, Ranchi 835 215, IN
1 Department of Remote Sensing, BIT Mesra, Ranchi 835 215, IN
Source
Current Science, Vol 119, No 8 (2020), Pagination: 1316-1321Abstract
This study was carried out to estimate biomass extraction from multi-frequency and multi-polarization of Synthetic Aperture Radar (SAR) data coupled with optical data. Further, the estimated biomass was validated with field-observed data. ALOS-2/PALSAR was utilized for retrieval of forest above-ground biomass (AGB) biophysical parameters. Subsequently, Sentinel- 2 optical data and 90 m TanDEM were used to identify the bare ground area for calculating pseudo height. Ground-truth data were utilized for estimation and validation of the modelled biomass from radar data. In this study, five allometric models were used. Multivariate regression models were trained using backscatter from the same acquisition (date) on 10 randomly selected samples from 21 field plots. The validation was carried out on the remaining 11 field plots. Co-validation method was used to validate these models. Biomass was estimated from radar data using regression models. Since the objective of the study was to present generalized biomass estimation models using backscatter information and AGB, the AGB value range 100–400 tonne/ha was estimated/mapped. Combined backscatter and height inputs were better than backscatter models. In the estimation of AGB, polarimetric information content and backscatter information played a significant role.Keywords
Allometric Model, Forest Biomass, Multifrequency, Multi-Polarization, Optical Data.Full Text