SRM University

About: SRM University is a education organization based out in Chennai, India. It is known for research contribution in the topics: Computer science & Population. The organization has 10787 authors who have published 11704 publications receiving 103767 citations. The organization is also known as: Sri Ramaswamy Memorial University.

Assessment of Caatinga response to drought using Meteosat-SEVIRI Normalized Difference Vegetation Index (2008-2016)

Abstract: The Caatinga semi-arid vegetation in Northeast region of Brazil (NEB) provides a unique opportunity for studying the vegetation in response to recurring droughts, because of its negative impacts on soil erosion. Surprisingly, however, the response of Caatinga vegetation to a recent multi-year drought across the entire semi-arid NEB has not been studied in detail. This study analyses the spatiotemporal patterns of drought impact on the Caatinga vegetation between 2008 and 2016. Yet previous research has shown that a linear relationship exists between rainfall and Caatinga vegetation at interannual timescale. Because of the strong large-scale control of precipitation, year-to-year rainfall variations have a notable degree of spatiotemporal heterogeneity in semi-arid NEB. We exploit this relationship by developing the local-to regional-scale rainfall-Normalized Difference Vegetation Index (NDVI) distribution over the Caatinga vegetation, using daily rainfall time series from in situ weather stations, and daily Meteosat Second Generation (MSG) NDVI time series. Results showed that the drought impact (2012–2015) through the rainfall deficit dynamics influenced the dynamics of vegetative drought in the Caatinga vegetation where exhibit a strong decrease in vegetation activity, contrasting with irrigated croplands that exhibit little sensitivity to drought. It is the longest, continuous drought on the historical record (1901 onwards). The severe drought year of 2012 affected more than 26% of the vegetated area in the region. Over the 2012–2016 period, the positive trend observed in vegetation greenness is largely explained by a positive trend in the rainfall over 45% of the Caatinga vegetation, with the three months lagged rainfall (R2 = 0.62 with p

Photovoltaic Integrated Hybrid Microgrid Structured Electric Vehicle Charging Station and Its Energy Management Approach

Abstract: A hybrid microgrid-powered charging station reduces transmission losses with better power flow control in the modern power system. However, the uncoordinated charging of battery electric vehicles (BEVs) with the hybrid microgrid results in ineffective utilization of the renewable energy sources connected to the charging station. Furthermore, planned development of upcoming charging stations includes a multiport charging facility, which will cause overloading of the utility grid. The paper analyzes the following technical issues: (1) the energy management strategy and converter control of multiport BEV charging from a photovoltaic (PV) source and its effective utilization; (2) maintenance of the DC bus voltage irrespective of the utility grid overloading, which is caused by either local load or the meagerness of PV power through its energy storage unit (ESU). In addition, the charge controller provides closed loop charging through constant current and voltage, and this reduces the charging time. The aim of an energy management strategy is to minimize the usage of utility grid power and store PV power when the vehicle is not connected for charging. The proposed energy management strategy (EMS) was modeled and simulated using MATLAB/Simulink, and its different modes of operation were verified. A laboratory-scale experimental prototype was also developed, and the performance of the proposed charging station was investigated.

Transition Metal Ion (Mn2+, Fe2+, Co2+, and Ni2+)-Doped Carbon Dots Synthesized via Microwave-Assisted Pyrolysis: A Potential Nanoprobe for Magneto-fluorescent Dual-Modality Bioimaging.

Abstract: Heteroatom-doped carbon dots (C-dots) have captured widespread research interest owing to high fluorescence and biocompatibility for multimodal bioimaging applications. Here, we exemplify a rapid, facile synthesis of ethylenediamine (EDA)-functionalized transition metal ion (Mn2+, Fe2+, Co2+, and Ni2+)-doped C-dots via one-pot microwave (MW)-assisted pyrolysis at 800 W within 6 min using Citrus limon (lemon) extract as a carbon source. During MW pyrolysis, the precursor extract undergoes simultaneous carbonization and doping of metal ions onto C-dot surfaces in the presence of EDA. The EDA-functionalized transition metal ion-doped C-dots (i.e., Mn/C, Fe/C, Co/C, and Ni/C-dots) are collectively termed as TMCDs. The water-soluble TMCDs exhibited a size of 3.2 ± 0.485 nm and were enriched with amino and oxo functionalities and corresponding metal-oxide traces on the surfaces, as revealed from Fourier transfer infrared and X-ray photoelectron spectroscopy analyses. Interestingly, TMCDs demonstrated excitation...

Efficient catalytic conversion of terminal/internal epoxides to cyclic carbonates by porous Co(II) MOF under ambient conditions: structure–property correlation and computational studies

Abstract: A mixed ligand three-dimensional neutral porous framework, {[Co(OBA)(L)]xG}n (CoMOF-1) (H2OBA = 4,4′-oxybis(benzoic acid); L = (E)-N′-(pyridin-4-ylmethylene)isonicotinohydrazide; G = DMF, EtOH, MeOH, H2O), was successfully synthesized via a hydrothermal and reflux method. The activated MOF (CoMOF-1′) not only showed good affinity toward CO2 molecules, but also exhibited a good catalytic performance for CO2 conversion with a variety of terminal and internal epoxides. Grand Canonical Monte Carlo (GCMC) simulation proved the strong interactions of CO2 molecules with the amide functional groups of the MOF. The Lewis acidity of the Co(II) centers endowed by the weakly chelated carboxylate from the OBA ligand and Lewis basicity originating from the acylamide functionality of the pyridyl-based Schiff base ligand L favored the efficient solvent-free cycloaddition reaction of CO2 with different epoxides. Strikingly, CoMOF-1′ exhibited good catalytic efficiency for CO2 coupled with various terminal epoxides at ambient temperature and pressure (1 bar, 60 °C, 12 h) and with a variety of internal epoxides at moderate reaction conditions (30 bar, 100 °C, and 8 h) with good yield and recyclability. Further, the binary heterogeneous catalyst showed good chemical stability, easy separation and recyclability (6 cycles) without a noticeable decrease in activity. To the best of our knowledge, this is the first investigation on a neutral porous MOF as a potential heterogeneous solvent-free catalyst toward CO2 utilization for internal epoxide under moderate reaction conditions. Based on the structural evidence, a plausible mechanism for the cycloaddition reaction was proposed, which is further reinforced by the relative energy of each stage obtained from periodic Density Functional Theory (DFT) calculations.