Earth system model and data frameworks

V. Balaji 한국기상학회 2008 한국기상학회 학술대회 논문집 Vol.2008 No.-

The architecture of Earth system models is informed by two considerations. One is the need to support a hierarchy ranging from idealized to comprehensive models: understanding the functioning of the Earth system involves constantly moving back and forth between simple and complex models. A second consideration is the tendency of model complexity to grow with time: some components of the physical climate system are initially considered external to the system being modeled, and with the growing maturity of both our physical understanding and the available computational power, these later become full-fledged model components. Modeling frameworks have emerged as a key methodology for supporting the architecture of Earth system models with multiple components. Simultaneously, the comparative analysis of output from multiple models, and against observational data analysis archives, has become a key methodology in reducing uncertainty in climate projections, and in improving forecast skill of medium- and long-term forecasts. There is considerable momentum toward simplifying such analyses by applying comprehensive community-standard metadata to observational and model output data archives. This has led to the development of data frameworks for simplifying the construction of multi-model data archives. This paper traces the evolution of modeling and data frameworks, and emerging new methodologies enabled by these powerful technologies.

Electrochemical determination of semicarbazide on cobalt oxide nanoparticles: Implication towards environmental monitoring

Balaji B. Mulik,Ajay V. Munde,Raviraj P. Dighole,Bhaskar R. Sathe 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.93 No.-

The electrochemical determination of semicarbazide (SCB) executed by using cobalt oxide (Co3O4)nanoparticle modified electrode which was fabricated by using simple precipitation method. The assynthesizednanoparticles have been well characterised by X-ray diffraction (XRD), Furrier transforminfra-red (FTIR), UV-visible (UV-Vis) spectroscopic techniques, energy dispersive analysis of X-ray(EDAX), BET surface area, thermogravimetric (TG) analysis and transmission electron microscopic (TEM)techniques. The XRD shows face centred cubic (FCC) structure, the FTIR demonstrated a major bandsappeared at 574 cm 1 and 669 cm 1 are suggesting the (Co-O) vibrational mode of Co3O4. The TEM ofCo3O4 NPs has been confirmed its ultra-small particle size is of2 nm 0.5 nm. Whereas, EDAX showsthe only cobalt and oxygen are available confirms Co3O4 having high BET surface area. The fabricatedCo3O4 acted as a highly sensitive electrochemical sensor for the determination of SCB by using linearSweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) in0.5 M KOH solution. Significantly, anodic onset potential observed at 0.2 V vs. SCE, linear range of scanrate and concentration (1 mM–100 mM) with (LOD 0.13 and LOQ 0.46) and high current and potentialstability with pH dependent behaviour confirms Co3O4 based electrocatalytic system is good for oxidativedetermination of SCB. The selectivity of the sensor also tested by using mixture of other environmentalactive species with SCB by using LSV measurements. This proposed system is applicable in food andpharmaceutical industries for the determination of SCB as an amperometric sensor.

Effect of Geometrical Parameters on Optimal Design of Synchronous Reluctance Motor

V. S. Nagarajan,V. Kamaraji,M. Balaji,R. Arumugam,N. Ganesh,R. Rahul,M. Lohit 한국자기학회 2016 Journal of Magnetics Vol.21 No.4

Torque ripple minimization without decrease in average torque is a vital attribute in the design of Synchronous Reluctance (SynRel) motor. As the design of SynRel motor is an arduous task, which encompasses many design variables, this work first analyses the significance of the effect of varying the geometrical parameters on average torque and torque ripple and then proposes an extensive optimization procedure to obtain configurations with improved average torque and minimized torque ripple. A hardware prototype is fabricated and tested. The Finite Element Analysis (FEA) software tool used for validating the test results is MagNet 7.6.0.8. Multi Objective Particle Swarm Optimization (MOPSO) is used to determine the various designs meeting the requirements of reduced torque ripple and improved torque performance. The results indicate the efficacy of the proposed methodology and substantiate the utilization of MOPSO as a significant tool for solving design problems related to SynRel motor.

Further results on mean cordial labeling for three star graph

V. Maheshwari,L. Vinothkumar,V. Balaji 장전수학회 2020 Proceedings of the Jangjeon mathematical society Vol.23 No.2

A vertex labeling h : V (G)→{0, 1, 2} is said to be a mean cordial labeling of G if it induces an edge labeling h* given by such that | vh(b)-vh(p)| ≤ 1 and | eh(b)-eh(p)|≤1, b, p∈{0, 1, 2}, where vh(r) and eh(r) denote the number of vertices and edges respectively labeled with r (r = 0, 1, 2). A graph G is said to be a mean cordial graph if it admits a mean cordial labeling. In this paper we proved that three star graph is a mean cordial labeling. If r = s < t, the three star graph K1,r ∧K1;s ∧K1;t is a mean cordial graph if and only if |s-t|≤3r+6 for 3r+s-7≤t≤3r+s+6; r = 1, 2, 3, …. and s = 1, 2, 3,….

A Comparative Study of Operating Angle Optimization of Switched Reluctance Motor with Robust Speed Controller using PSO and GA

V. Vasan Prabhu,V. Rajini,M. Balaji,V. Prabhu 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.2

This paper’s focus is in reducing the torque ripple and increasing the average torque by optimizing switching angles of 8/6 switched reluctance motor while implementing a robust speed controller in the outer loop. The mathematical model of the machine is developed and it is simulated using MATLAB/Simulink. An objective function and constraints are formulated and Optimum turn-on and turn-off angles are determined using Particle swarm optimization and Genetic Algorithm techniques. The novelty of this paper lies in implementing sliding mode speed controller with optimized angles. The results from both the optimization techniques are then compared with initial angles with one of them clearly being the better option. Speed response is compared with PID controller.

A Comparative Study of Operating Angle Optimization of Switched Reluctance Motor with Robust Speed Controller using PSO and GA

Prabhu, V. Vasan,Rajini, V.,Balaji, M.,Prabhu, V. The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.2

This paper's focus is in reducing the torque ripple and increasing the average torque by optimizing switching angles of 8/6 switched reluctance motor while implementing a robust speed controller in the outer loop. The mathematical model of the machine is developed and it is simulated using MATLAB/Simulink. An objective function and constraints are formulated and Optimum turn-on and turn-off angles are determined using Particle swarm optimization and Genetic Algorithm techniques. The novelty of this paper lies in implementing sliding mode speed controller with optimized angles. The results from both the optimization techniques are then compared with initial angles with one of them clearly being the better option. Speed response is compared with PID controller.

Investigations on electrical properties of (PVA:NaF) polymer electrolytes for electrochemical cell applications

P. Balaji Bhargav,V. Madhu Mohan,A.K. Sharma,V.V.R.N. Rao 한국물리학회 2009 Current Applied Physics Vol.9 No.1

Solid polymer electrolytes based on poly (vinyl alcohol) (PVA) complexed with sodium fluoride (NaF) at different weight percent ratios were prepared using solution cast technique. The structural properties of these electrolyte films were examined by XRD studies. The XRD data revealed that the amorphous domains of PVA polymer matrix increased with increase of NaF salt concentration. The complexation of the salt with the polymer was confirmed by FT-IR studies. Electrical conductivity was measured in the temperature range of 303–373 K and the conductivity was found to increase with the increase of dopant concentration as well as temperature. The dielectric constant (ε') increased with the increase in temperature and decreased with the increase in frequency. A loss peak was identified at 365 K in the dielectric loss spectra and is attributed to the orientation of polar groups. Measurement of transference number was carried out to investigate the nature of charge transport in these polymer electrolyte films using Wagner’s polarization technique and Watanabe technique. Transport number data showed that the charge transport in these polymer electrolyte systems was predominantly due to ions and in particular due to anions. Using these polymer electrolytes, solid state electrochemical cells were fabricated. Various cell parameters like open circuit voltage (OCV), short circuit current (SCC), power density and energy density were determined. Solid polymer electrolytes based on poly (vinyl alcohol) (PVA) complexed with sodium fluoride (NaF) at different weight percent ratios were prepared using solution cast technique. The structural properties of these electrolyte films were examined by XRD studies. The XRD data revealed that the amorphous domains of PVA polymer matrix increased with increase of NaF salt concentration. The complexation of the salt with the polymer was confirmed by FT-IR studies. Electrical conductivity was measured in the temperature range of 303–373 K and the conductivity was found to increase with the increase of dopant concentration as well as temperature. The dielectric constant (ε') increased with the increase in temperature and decreased with the increase in frequency. A loss peak was identified at 365 K in the dielectric loss spectra and is attributed to the orientation of polar groups. Measurement of transference number was carried out to investigate the nature of charge transport in these polymer electrolyte films using Wagner’s polarization technique and Watanabe technique. Transport number data showed that the charge transport in these polymer electrolyte systems was predominantly due to ions and in particular due to anions. Using these polymer electrolytes, solid state electrochemical cells were fabricated. Various cell parameters like open circuit voltage (OCV), short circuit current (SCC), power density and energy density were determined.

Room-temperature successive ion transfer chemical synthesis and the efficient acetone gas sensor and electrochemical energy storage applications of Bi₂O₃ nanostructures

Shinde, Pritamkumar V.,Ghule, Balaji G.,Shinde, Nanasaheb M.,Xia, Qi Xun,Shaikh, Shoyebmohamad,Sarode, A. V.,Mane, Rajaram S.,Kim, Kwang Ho The Royal Society of Chemistry 2018 New journal of chemistry Vol.42 No.15

<P>The acetone gas sensor and electrochemical supercapacitor applications of bismuth oxide (Bi2O3) nanostructures, synthesised using a facile and cost-effective quaternary-beaker mediated successive ion transfer wet chemical method and deposited onto soda-lime-glass (SLG) and Ni-foam substrates, respectively, are explored. The as-deposited Bi2O3 nanostructures on these substrates exhibit polycrystalline nature and a slight change in their surface appearance (<I>i.e.</I> upright-standing nanoplates on SLG and a curvy nanosheet structure on Ni-foam), suggesting the importance of the deposition substrate in developing Bi2O3 morphologies. The Bi2O3 nanoplate gas sensor on the SGL demonstrated a room temperature sensitivity of 41%@100 ppm for acetone gas, whereas the nanosheet structure of Bi2O3 on the Ni-foam elucidated a specific capacitance of 402 F g<SUP>−1</SUP> at 2 mA cm<SUP>−2</SUP>, long-term cyclability, and rate capability with moderate chemical and environmental stability in a 6 M KOH electrolyte solution. The Bi2O3//graphite pencil-type asymmetric supercapacitor device revealed a specific capacitance as high as 43 F g<SUP>−1</SUP>, and an energy density of 13 W h kg<SUP>−1</SUP> at 793 W kg<SUP>−1</SUP> power density, turning a light emitting diode ON, with considerable full-brightness light intensity, during the process of discharging.</P>

DC and RF Performance Analysis of Extended Field Plated AlGaN/GaN/β-Ga2O3 HEMT

R. Karpagam,S. Leones Sherwin Vimalraj,G. K. Sathishkumar,V. Megala,Y. Gowthami,B. Balaji 한국전기전자재료학회 2023 Transactions on Electrical and Electronic Material Vol.24 No.5

In this work, High Electron Mobility Transistor is grown on various Substrates such as silicon (Si), silicon carbide (SiC), and sapphire substrate to exhibit a negative threshold voltage, whereas grown on β-gallium oxide (β-Ga2O3) to exhibit a positive threshold voltage. The optimization is done by using the pi-shaped gate and filed plate towards the drain and triple tooth metal for the proposed structure. In this, work Al0.8Ga0.2 N /AlN /GaN /AlN /Al0.4Ga0.6 N /GaN /AlN / Al0.8Ga0.2 N / β-Ga2O3 HEMT is proposed to improve the breakdown voltage, subthreshold swing. Β-Ga2O3 is prominent material to reduce the leakage current in the structure. It is observed from the obtained results that the Breakdown voltage for Si is 15 V, SiC is 20 V, Sapphire is 114 V, β-Ga2O3 is 125 V,d Unilateral power gain of 21.12dB, 19.56dB, 18.9dB, 9.5dB, at 851 GHz, 774 GHz, 738 GHz, 318 GHz when the proposed structure is grown on β-Ga2O3, SiC, Sapphire, Si substrates. In the proposed HEMT there is a compromise between frequency and breakdown voltage. If one factor improves the other reduces. But by using β-Ga2O3 as a substrate the achievement of both factors is possible. This is possible because of properly layering hetero-materials with matched lattice constant. β-Ga2O3 is a material that is a trend in the market and which resulted in intensive research. In the proposed structure Ferroelectric material i.e. lead Zirconate titanate oxide (PbZrTiO3) is used as a gate to reduce the power consumption and to increase the storage capacity in a unit area. Ferroelectric materials possess elevated dielectric constant and it has the capability of storing more charge per unit area when compared to other materials. In the small area, this material can store more data with low power consumption.

Sensitivity Analysis of Geometrical Parameters of a Switched Reluctance Motor with Modified Pole Shapes

Balaji, M.,Ramkumar, S.,Kamaraj, V. The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.1

A major problem in Switched Reluctance Motor (SRM) is torque ripple, which causes undesirable acoustic noise and vibration. This work focuses on reducing the undesirable torque ripple in SRM by modifying stator and rotor geometry. This paper presents a comparative study on torque ripple minimization in SRM with modified pole shapes such as stator pole taper, stator pole face with non-uniform air gap and pole shoe attached to rotor pole. Further this paper presents a detailed sensitivity analysis of the effect of different geometrical parameters that alter the pole face shapes on the performance of SRM. The analysis is performed using finite-element method considering average torque and torque ripple as performance parameters. Based on the analysis, a design combining stator pole taper with non-uniform air gap is proposed to improve the torque characteristics of SRM. The dynamic characteristics of the proposed design are simulated and the results show satisfactory reduction in torque ripple.