1,722,006 research outputs found
Interview with Avinash Kumar, Creative Director & Co-Founder, Quicksand Design Studio
Full text linkInterview with Avinash Kumar, Creative Director & Co-Founder, Quicksand Design Studio, India
Vegetation activity enhanced in India during the COVID-19 lockdowns: evidence from satellite data
No full textThe Severe Acute Respiratory Syndrome-COronaVIrus Diseases 2019 (SARS-COVID-19) has sternly affected the entire world in terms of human health, loss of lives, and huge economic losses. However, pandemic-triggered lockdown (LD) events (as a preventive measure) have compelled to stop or reduce major economic activities, exerting positive impacts on the terrestrial environment. We deployed a variety of satellite products (i.e., normalized difference vegetation index (NDVI), solar-induced chlorophyll fluorescence (SIF), and aerosol optical depth (AOD)) along with gridded climatic dataset (temperature (TEMP), precipitation (PREC), and net radiation (NR)) to quantify the changes in vegetation activity (greenness and productivity) during the LD period over the Indian biogeographic provinces (BGPs) as compared to the average conditions over the previous three years (2017-2019). The analysis of the NDVI and SIF data revealed that vegetation greenness and productivity significantly enhanced during LD periods (by up to 37 to 55%, respectively). The influence of climatic drivers (PREC, TEMP, and NR) on vegetation activity was also investigated. We found that the enhancement in the vegetation activity (over BGPs) during the LD period was not entirely driven by the climatic parameters, and was therefore inferred to be also influenced by the LD events. Moreover, vegetation activity around the mining clusters were largely improved during the LD period (by up to 78%) over the coal mining, followed by iron ore mining (up to 63%), and stone mining (up to 41%) clusters) regions. In a nutshell, it can be deliberated that COVID-triggered preventive measures (i.e., country-level LD, travel bans, industry ban, curtail in mining capacity, among others) likely enhanced vegetation health and productivity. Thereby, regulatory measures can be seen as a viable option for improving the terrestrial environmental conditions in the context of climate change in the near future
A new approach for prediction of foliar dust in a coal mining region and its impacts on vegetation physiological processes using multi‐source satellite data sets
No full textEstimating foliar dust (FD) is essential in understanding the complex interaction between FD, vegetation, and the environment. The elevated FD has a significant impacts on vegetation physiological processes. The present study aims to explore the potential of multi-sensor optical satellite data sets (e.g., Landsat-8, 9; Sentinel-2B, and PlanetScope) in conjunction with in situ data sets for FD estimation over the Jharsuguda coal mining region in Eastern India. The efficacy of different spectral bands and various radiometric indices (RIs) was tested using linear regression models for FD estimation. Furthermore, the study attempts to quantify the impacts of FD on vegetation's physiological processes (e.g., carbon uptake, transpiration, water use efficiency, leaf temperature) through proxy data sets. The key findings of the study uncovered sensor-specific and common trends in vegetation spectral profiles under varying FD concentrations. A saturation threshold was observed around 50 g/m
2 of FD concentration, beyond which additional FD concentration exhibited limited impact on spectral reflectance. On the other hand, the assessment of FD estimation models revealed distinct performances and shared trends across various satellite sensors. Notably, near-infrared and shortwave infrared-1 bands, along with certain RIs, such as the Global Environmental Monitoring Index and the Non-Linear Index, emerged as pivotal for accurate FD estimation. Besides, the study results revealed that vegetation-associated carbon uptake experienced a ∼2 to 3 gC reduction for every additional gram of FD per square meter. Moreover, the vegetation transpiration reduction per unit of FD ranged from approximately 0.0005 to 0.0006 mm/m
2/day, highlighting a moderate impact on transpiration levels. These findings aid a significant evidence base to our understanding of FD's impact on vegetation physiological processes.</p
An Experimental Investigation on Spray Characteristics of Waste Cooking Oil, Jatropha, and Karanja Biodiesels in a Constant Volume Combustion Chamber
No full textIn this study, macroscopic spray characteristics of Waste cooking oil (WCO), Jatropha oil, Karanja oil based biodiesels and baseline diesel were compared under simulated engine operating condition in a constant volume spray chamber (CVSC). The high pressure and high temperature ambient conditions of a typical diesel engine were simulated in the CVSC by performing pre-ignition before the fuel injection. The spray imaging was conducted under absence of oxygen in order to prevent the fuels from igniting. The ambient pressure and temperature for non-evaporating condition were 3 MPa and 300 K. Meanwhile, the spray tests were performed under the ambient pressure and temperature of 4.17 MPa and 804 K under evaporating condition. The fuels were injected by a common-rail injection system with injection pressure of 80 MPa. High speed Mie-scattering technique was employed to visualize the evaporating sprays. Liquid tip penetration length, spray cone angle and spray area were determined from captured images. The equivalence ratio along the axial direction of the spray was also calculated based on mathematical correlations. Results showed that biodiesels had longer spray tip penetration length and narrow spray cone angle than those of baseline diesel. Amongst the biodiesels, Jatropha and Karanja biodiesels exhibited longer spray tip penetration length and narrower spray angle than those of Waste cooking oil biodiesel. On the other hand, baseline diesel showed much shorter liquid tip penetration length and faster evaporation process than biodiesels. The reason is that higher density and viscosity of biodiesels attenuated the fuel atomization and evaporation process. However, despite deteriorated atomization characteristics, biodiesels showed lower equivalence ratio than baseline diesel due to inherent oxygen content in the fuel molecules
Invited commentary: A patient of pulmonary embolism and online conversational learning among global medical students through a journal review platform
Full text linkCommentaryVivek Podder, Madhava Sai Sivapuram, Avinash Kumar Gupta, Rakesh Biswa
Near Nozzle Flow and Atomization Characteristics of Biodiesel Fuels in a Constant Volume Chamber
No full textQuantifying the impacts of opencast mining on vegetation dynamics over eastern India using the long-term Landsat-series satellite dataset
No full textEnhanced spatio-temporal and up-to-date information on vegetation dynamics at various spatial scales are imperative in understanding the human, biosphere, and atmosphere interactions. Thus, the present study attempts to derive the vegetation greenness trends with the medium spatial resolution (30 m) satellite data at the regional scale with the support of Google Earth Engine (GEE) cloud platform. The long-term Landsat series satellite dataset was employed to characterize vegetation greenness trends using the Mann-Kendall test over the mining-dominated regions of Eastern India (Jharkhand and Odisha states) for two study periods, viz. earlier (1988–2004) and later (2000−2020). The key findings revealed that ∼1285 km
2 (2.97%) and 1688 km
2 (3.91%) areas over Jharkhand state and ∼ 5213 km
2 (5.68%) and 2940 km
2 (3.20%) areas over Odisha state showed the negative vegetation greenness trend (indicative of decreasing vegetation activity) during 1988–2004 and 2000–2020, respectively. It was observed that the major anthropogenic activities, particularly opencast mining, are the major factor for vegetation degradation in Jharkhand and Odisha states, contributing to ∼3–5.7% vegetation degradation during the study periods. The negative vegetation greenness trend patches were mainly observed in mining sites, settlement encroachments, construction sites, roadways, logging sites, etc. The drastic rise in the intensity of mining activities in the last two decades (2000–2020) has led to massive vegetation destruction compared to the earlier period (1988–2004). Furthermore, the key climatic parameters (i.e., precipitation, temperature, downward radiation, and soil moisture) have less control over the long-term vegetation greenness trends in the mining-dominated regions (∼ 27%) in contrast to forest regions (∼ 47%). The findings of the study shall be helpful to the policy-makers, stakeholders, environmentalists, and government bodies to formulate and implement various sustainable development programs in the mining-dominated regions to ensure ecological conservation and enhance ecological services.
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Evaluating impacts of opencast stone mining on vegetation primary production and transpiration over Rajmahal Hills
No full textOpencast mining has significantly triggered vegetation degradation in many ecologically sensitive regions across the globe. The detailed spatio-temporal information on mining-induced vegetation degradation and associated primary production loss are crucial inputs to authorities and policymakers to frame and implement sustainable development programs in the mining regions to conserve vegetation ecology. Thus, the present study aimed to decipher the mining-induced vegetation cover and subsequent productivity losses over the Rajmahal Hills in Jharkhand (India). The Gross Primary Productivity (GPP), Net Primary Productivity (NPP), and Vegetation Transpiration (VT) datasets were used for analyzing the mines-induced losses in vegetation cover and associated productivity. The key findings indicated a loss of vegetation cover by ~340 km2 and an expansion of the mining area by ~54 km2 over the Rajmahal Hills during 1990–2020. The change detection analysis at the decadal period revealed that ~3.06 km2, 8.10 km2, and 22.29 km2 of vegetation cover were lost only due to the mining activity during 2000–2010, 2010–2020, and 2000–2020, respectively. The replacement of vegetation cover by mining area has caused GPP loss of 0.01 tonnes carbon (tC) per day, 0.04 tC/day, and 0.09 tC/day; NPP loss of ~1.25 tC, 2.77 tC, and 7.27 tC; VT loss of 5200 mm/day, 13,630 mm/day, and 30,190 mm/day during 2000–2010, 2010–2020, and 2000–2020, respectively. Hence, the present study revealed that the mining-induced vegetation losses have caused an alteration of carbon sequestration, carbon stock, and VT over the Rajmahal Hills
In-Cylinder Spray and Combustion Investigations in a Heavy-Duty Optical Engine Fueled With Waste Cooking Oil, Jatropha, and Karanja Biodiesels
No full textIn this experimental study, spray and combustion characteristics of a single cylinder optical engine were evaluated by varying the fuel injection pressure (FIP) (40, 80, and 120 MPa). Karanja, Jatropha, and waste cooking oil (WCO) biodiesels were the test fuels and their results were compared with baseline mineral diesel. There was no significant difference observed in the spray tip penetration amongst all test fuels, however the spray cone angles of biodiesels were slightly higher than baseline mineral diesel. Mineral diesel showed relatively shorter injection delay compared to biodiesels at 40 and 80 MPa FIP. Jatropha and Karanja biodiesels showed higher flame luminosity at all FIPs, while WCO biodiesel showed lower flame luminosity, especially at higher FIPs of 80 and 120 MPa, primarily due to lower viscosity of WCO biodiesel. Flame spatial fluctuation (FSF) and flame nonhomogeneity (FNH) were also found to be higher for biodiesels at lower FIP of 40 MPa. Karanja and Jatropha biodiesels showed higher FSF and FNH at higher FIPs compared to WCO biodiesel.
Microscopic Spray Characteristics of Biodiesels Derived From Karanja, Jatropha, and Waste Cooking Oils
No full textThis study aims to assess the microscopic characteristics of Jatropha, Karanja, and Waste cooking oil-based biodiesels vis-a-vis conventional diesel under different ambient conditions in order to understand the in-cylinder processes, while using biodiesels produced from different feedstocks in the compression ignition engines. All test-fuels were injected in ambient atmosphere using a common-rail direct injection (CRDI) fuel injection system at a fuel injection pressure (FIP) of 40 MPa. Microscopic spray characteristics were measured using phase Doppler interferometer (PDI) in the axial direction of the spray at a distance of 60-90 mm downstream of the nozzle and at 0 to 3-mm distance from the central axis in the radial direction. All biodiesels exhibited relatively larger Sauter mean diameter (SMD) of the spray droplets and higher droplet velocities compared to baseline mineral diesel, possibly due to relatively higher fuel viscosity and surface tension of biodiesels. It was also observed that SMD of the spray droplets decreased with increasing distance in the radial and axial directions and the same trend was observed for all test-fuels.
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