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Modelling the Particulate Backscattering Coefficients of Turbid and Productive Coastal Waters
V. Gomathisankaraprasad Harharasudhan,Palanisamy Shanmugam 한국해양과학기술원 2019 Ocean science journal Vol.54 No.2
An optical model is developed to predict the spectral backscattering coefficients of phytoplankton (bbph(λ)) and non-living particles (bbss(λ)) in turbid and productive coastal waters. This model computes bbph(λ) and bbss(λ) values based on the measured absorption and attenuation coefficients and water constituents’ concentrations. The predicted values are validated with independent in-situ data from four different water types and compared with results from the independent model. The findings revealed that, in sediment-dominated coastal waters, the backscattering coefficient of phytoplankton is relatively smaller than that of non-living particles. In productive waters, the contribution by phytoplankton is significant due to high chlorophyll a concentration and the influence of complex morphology, intracellular structure and composition of phytoplankton. The results further showed that living algal matter in turbid productive waters may have a significant influence on the backscattering process and its spectral dependency which will have important implications for our understanding of the relationship between the backscattering to scattering ratio, particle size distribution and related properties.
Palanisamy R.,Karthikeyan D.,Vidyasagar S.,Kalyanasundaram V.,Selvakumar K.,Vijayakumar K.,Selvabharathi D. 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.4
In this paper, three phase four wire fi ve level Neutral Point Clamped Inverter (NPCI) based Static synchronous Compensator (STATCOM) is implemented for reactive power control and neutral current elimination. Three dimensional Space Vector Pulse Width Modulation (3D-SVPWM) control strategy is developed to control this 5-level NPC inverter. The behaviour of static synchronous compensator is analyzed and reactive power control is done using constant DC voltage. The objective of this compensating method is to provide balanced and sinusoidal source currents under unbalanced and nonlinear load conditions and reactive power control. The 3D-SVPWM technique provides reduced harmonic content in output voltage and current, controlled source current, minimized common mode voltage and improved output voltage. In 3D-SVPWM, switching pulses are generated with non-redundant switching states, which lead to reduce the complexity in switching time calculation and computational time is less. The highlights of the paper includes the neutral current is reduced to 0.25A, source current harmonics is minimized and it provides balanced and sinusoidal source currents with help of STATCOM compensation. The simulation and experimental results demonstrates the sinusoidal and harmonics free source current and minimized neutral current for four wire fi ve level NPCI based STATCOM.
R. Palanisamy,V. Shanmugasundaram,S. Vidyasagar,V. Kalyanasundaram,K. Vijayakumar 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.6
A Space Vector Pulse Width Modulation (SVPWM) control strategy is implemented for capacitor voltage balancing of Flying Capacitor (FC) based 4-level Neutral Point Clamped (NPC) inverter. This fl ying capacitor based 4-level NPC inverter is developed for medium voltage and high power applications. This system includes 6 power switching devices, 2 clamping diodes and 2 fl ying capacitors per leg. The fl ying capacitors ensure to operate inverter normally and all the switching devices share the voltage stresses in identical manner. Also it controls the voltage across each capacitor and maintained at V dc /3 times of applied dc voltage. The proposed SVPWM method takes advantage of utilizing redundancy switching states to control and balance the voltage across the capacitor using nearest switching state vector selection method. Moreover, this system provides reduced total harmonic distortion (THD), and minimized voltage stress. The control technique is implemented without using any look-up tables or eff ective logic tables or trigonometric functions. The simulation and experimental results of this proposed verifi ed are verifi ed using Matlab-simulink and FPGA controller respectively.
Venkataramana Murthy V. Padmanabhan,Senthil Kumar Palanisamy 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.3
This work presents an experimental comparison of exergy efficiency (EE), irreversibility at the process 1-2 (evaporator exit to com-pressor inlet), 2-3 (compressor inlet to condenser inlet), 3-4 (condenser inlet to expansion valve inlet), 4-5 (expansion valve inlet to evaporator inlet) and 5-1 (evaporator), and coefficient of performance (COP) of R22, and its substitutes R134a, R290 and R407C in vapor compression refrigeration system (VCRS) of an air conditioner. In addition, the effects of air temperature in the freezer with reference to environment states on irreversibility and EE have been investigated. At -18°C air temperature in the freezer, 33°C reference environment state and 42% relative humidity refrigerants R22 and its substitutes R134a, R290 and R407C VCRSs the total irreversibilities are 665.7, 753.5, 582.1 and 677 W, and EEs are 22.9, 14.2, 26.5 and 20.6%, respectively. The refrigerant R290 is the best performer among candidate refrigerants but it suffers from flammability. Thus, R407C can considerably be used to replace R22.
G. Rexin Thusnavis,T. V. Archana,P. Palanisamy 한국부식방식학회 2022 Corrosion Science and Technology Vol.21 No.1
The o-Vanillin - Glutamine Schiff base [2-Hydroxy-3-Methoxy BenzylidineCarbomyl) -2-Butanoic Acid] was examined for low carbon steel corrosion inhibition in acid media. Weight loss studies were carried out at three different temperatures to determine the inhibition efficiency (IE). Electrochemical impedance spectroscopy revealed that the charge transfer resistance controlled the corrosion reaction and Tafel polarization indicated that the Schiff base acts as mixed mode of inhibitor. SEM images were recorded for the surface morphology of the low carbon steel surface. DFT studies revealed corrosion control mechanisms using quantum chemical parameters such as EHOMO, ELUMO, energy gap (ΔΕ), chemical Hardness (η), chemical Softness (σ), Electronegativity (χ), and the fraction of electron transferred (ΔN) , which is calculated using Gaussian software 09. The gas-phase geometry was fully optimized in the Density Functional Theory (DFT/B3LYP-6-31G (d)).The DFT results are in good agreement with the experimental results. All the results proved that the Schiff Base (2-Hydroxy-3-Metoxy BenzylidineCarbomyl) -2-Butanoic is a suitable alternative for corrosion inhibition of low carbon steel in acid media.