120 research outputs found
Disentangle the short-term forest degradation over most fire-affected parts of Western Himalaya, India
No full textThe tropical forest contributes around 5% to 15% of atmospheric carbon emissions, which are mostly anthropogenic. But there are large uncertainties in the quantification of these emissions from its sources. The remote-sensing data offers a practical opportunity to monitor and assess different forest disturbances. Western Himalayan forest is often affected by fire events, mostly during (pre-monsoon) dry and warm periods. In this study, we present a way to monitor the forest degradation condition using spectral mixture analysis (SMA) and surface reflectance of Landsat-8 data from 2014 to 2019. The Normalized Degradation Fraction Index (NDFI) has been performed by using spectral end member fractions of green vegetation (GV), non-photosynthetic vegetation (NPV), soil, and shade in the Google Earth Engine (GEE) cloud platform. The NDFI shows considerable spatial correspondences with clusters of fire spots during the pre-monsoon period. Around 3% to 9% of the forest burned area transformed to partially to highly degraded forest. The overall trend of degradation fraction (NDFI) over total forest cover shows a significant negative trend over a considerable area. Thus, Landsat-8-based SMA and NDFI demonstrate a potential way to identify forest degradation mediated by forest fires, although remote sensing-based approaches are limited in their capacity to accurately detect forest disturbances. Furthermore, field-based studies are needed to monitor the potentialities of the NDFI approach in forest degradation identification
Development and experimental study of machining parameters in ultrasonic vibration-assisted turning
Get PDFIn recent years applications of hard materials in different industries, like aerospace, defence and petrochemicals sectors etc. have been increased remarkably. The machining of these hard materials is very difficult in conventional turning process. Ultrasonic assisted turning is a suitable and advanced process for machining hard and brittle material because of its intermittent cutting mechanism. In the present work, an ultrasonic vibratory tool (UVT) is designed and analyzed using ANSYS ® environment for calculation of its natural frequency and working amplitude of vibration. An ultrasonic assisted turning system is designed considering cutting tool as a cantilever beam. Experimental study has been carried out to find the difference between ultrasonic- assisted and conventional turning at different cutting conditions taking carbon steel (a general purpose engineering material) as the work piece material. It is found that ultrasonic assisted turning reduces the surface roughness and cutting force in comparison with conventional turning. It is well known that cutting force and surface finish/roughness are two major parameters which affect the productivity of the turning process. In the present work, Grey based Taguchi method is used to optimize both cutting force and surface roughness to find the best possible machining parameters under the used experimental working conditions. Also, second order response models for the surface roughness and cutting force are developed and confirmation experiments are conducted
Vegetation trend analysis and change quantification based on time series satellite data for Northeast India
No full textMapping vegetation change and dynamics is an essential input for natural resource management and ecosystem-related policy design. Trend analysis on vegetation indices (VI) derived from satellite images is a common way of mapping vegetation change due to its ease of use, generalizability, and acceptable accuracy for large-scale applications. To better quantify the vegetation change, the current study analyzes the long-term spatio-temporal variability of vegetation and trend breaks in vegetation vigour for the Northeast region of India based on the normalized difference vegetation index (NDVI) derived from moderate resolution imaging spectroradiometer (MODIS) data as well as NDVI derived from Global Inventory Modelling and Mapping Studies (GIMMS). This chapter summarizes approaches to detecting vegetation change and methods for observing spatio-temporal trends based on long-term NDVI records. Standard anomaly-based methods designed to overcome assumptions of long-term linearity in time series analysis are also discussed. Finally, a novel approach for identifying breaks in vegetation trends is presented to quantify the year during which the trend break took place by decomposing the time series information on vegetation vigour into its seasonal and non-seasonal components based on bi-monthly data from 1982 to 2020. The results demonstrate nonlinear changes in the trend of natural vegetation. A gradual decline in positive anomaly was observed between 2006 and 2008 in Arunachal Pradesh. Positive anomalies were noticed in 2003 for the states of Meghalaya and Assam. Our findings indicated vegetation frequency of negative anomalies ranged from 53.6% to 27.5%, particularly in the regions of Arunachal Pradesh and Assam. The breaks in trends of vegetation were mainly identified in the years 2005, 2010, 2014, and 2019
Eco-Friendly Machining of Ni-Based Superalloy with High-Velocity Mist Nozzle
No full textIn the manufacturing sector, there is a constant effort to improve procedures to produce high-quality goods at a lower cost. Academics are improving aspects of the metal machining process to increase efficiency. New techniques have been developed to achieve this, utilizing better production procedures and more advanced technological tools. It is essential to optimize production processes and minimize their negative impact on the environment and human health. Therefore, environmentally friendly machining operations, such as minimal quantity lubrication (MQL) machining, are being implemented. MQL is used in metal removal processes like milling, drilling, and turning to reduce the use of cutting fluids. The effectiveness of MQL can be improved by misting the flank face and the area near the chip tool contact. A turning center suitable for MQL configuration has been developed as part of the current research project. During the turning of Inconel 718 under dry, conventional fluid, and conventional fluid under MQL process conditions, forces and surface roughness data were examined
Assessment of Bio-dielectric Calophyllum inophyllum (Polanga) Oil in Electro-discharge Machining: A Step Toward Sustainable Machining
No full textModeling of cutting force in MQL machining environment considering chip tool contact friction
No full textComparison of Classifiers for Speech Emotion Recognition (SER) with Discriminative Spectral Features
No full textA comparative study of recent lubri-coolant strategies for turning of Ni-based superalloy
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