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Sarangapany Saran,Gangarapu Manjari,Patchaiyappan Arunkumar,Suja Purushothaman Devipriya 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.11
Ag deposited TiO2 was prepared by simple chemical reduction method and its photocatalytic efficiency was evaluated for the decolorization of methylene blue dye using pilot scale slurry type falling film reactors (FFR) under sunlight. The characterization of the prepared catalysts by XRD, TEM, EDAX, DRS and PL confirmed that silver, which acts as electron trap, was deposited over the TiO2 surface. The operational parameters, such as catalyst loading, concentration of the dye solution, pH of the slurry, addition of oxidizing agents and effect of different substrates, were optimized. The photocatalytic efficiency of Ag deposited TiO2 increased two-fold times than pure TiO2 and the maximum decolorization of dye was observed under acidic conditions. The reaction rate significantly increased with the addition of oxidizing agent H2O2. The ceramic tile as well as double skin reactor have higher photocatalytic efficiency than glass as substrate. In addition, Ag-deposited TiO2 photocatalyst could be easily recovered by simple sedimentation process and reused for repeated experimental cycles with more than 95% decolorization efficiency.
Chaitanya Sarangapani,Peng Lu,Patrice Behan,Paula Bourke,P.J. Cullen 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.59 No.-
In this study an atmospheric air plasma reactor was studied for the degradation of HA and THMs in water. Plasma treatment showed significant breakdown efficacies for HA and THMs. At an applied voltage of 80 kV about 93% of HA and >70% of THMs were degraded after 15 min and 30 min treatment time respectively, with the degradation following a first order kinetic model. Plasma induced reactive species including nitrates and H2O2 were quantified in the treated water. The results of FTIR analysis revealed that the molecular structure of HA was altered by the plasma treatment, with a decrease in aromaticity observed.
Decentralized Fault Tolerant Control of a Class of Nonlinear Interconnected Systems
Hasan Ferdowsi,Sarangapani Jagannathan 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.2
In this paper, a novel decentralized fault tolerant controller (DFTC) is proposed for interconnected nonlinearcontinuous-time systems by using local subsystem state vector alone in contrast with traditional distributedfault tolerant controllers or fault accommodation schemes where the measured or the estimated state vector of theoverall system is needed. The proposed decentralized controller uses local state and input vectors and minimizes thefault effects on all the subsystems. The DFTC in each subsystem includes a traditional controller term and a neuralnetwork based online approximator term which is used to deal with the unknown parts of the system dynamics,such as fault and interconnection terms. The stability of the overall system with the proposed DFTC is investigatedby using Lyapunov approach and the boundedness of all signals is guaranteed in the presence of a fault. Therefore,the proposed controller enables the system to continue its normal operation after the occurrence of a fault, as longas it does not cause failure or break down of a component. Although the decentralized fault tolerant controller isdesigned mainly for large-scale systems where continuous transmissions between subsystems is not possible, it canalso be applied to small-scale systems where sensor measurements are available for use in all subsystems. Finallythe proposed methods are verified and compared in simulation environment.
Purushothaman Devipriya,Arunkumar Patchaiyappan,Sarangapany Saran 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.7
Separation of TiO2 from aqueous suspension is a major constraint in heterogeneous photocatalytic water treatment. As an alternative for existing less effective immobilization techniques, the application of plant based coagulant for the recovery and reuse of TiO2 was investigated for the first time. Aqueous extract derived from seeds of Strychnos potatorum was found to be an effective coagulant for the sedimentation of TiO2. Further, the potential for recovery and reuse of the sedimented photocatalysts TiO2, was investigated by photocatalytic degradation of rhodamine B and terephthalic acid tests. The photocatalytic degradation experiments with recovered catalyst obey pseudo first-order kinetics with enhanced photocatalytic activity than that of the pure TiO2. The investigation of recovered catalysts with XRD, BET, SEM etc., suggests that there is no change in surface and morphological properties when compared with pure TiO2 and the recovered catalysts are highly suitable for recycle and reuse.
Quantum-chemical Investigation of Substituted s-Tetrazine Derivatives as Energetic Materials
Ghule, Vikas D.,Sarangapani, Radhakrishnan,Jadhav, Pandurang. M.,Tewari, Surya. P. Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.2
s-Tetrazine is the essential candidate of many energetic compounds due to its high nitrogen content, enthalpy of formation and thermal stability. The present study explores the design of s-tetrazine derivatives in which different $-NO_2$, $-NH_2$ and $-N_3$ substituted azoles are attached to the tetrazine ring via C-N linkage. The density functional theory (DFT) is used to predict the geometries, heats of formation (HOFs) and other energetic properties. The predicted results show that azide group plays a very important role in increasing HOF values of the s-tetrazine derivatives. The densities for designed molecules were predicted by using the crystal packing calculations. The introduction of $-NO_2$ group improves the density as compared to $-N_3$, and $-NH_2$ groups and hence the detonation performance. Bond dissociation energy analysis and insensitivity correlations revealed that amino derivatives are better candidates considering insensitivity and stability.
Hasan Ferdowsi,Jia Cai,Sarangapani Jagannathan 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.3
This paper presents a new model-based fault detection and failure prediction framework for a class of multi-input and multi-output (MIMO) nonlinear distributed parameter systems (DPS) described by partial differential equations (PDE) with actuator and sensor faults. The fault functions cover both abrupt and incipient faults. A Luenberger type observer is used to monitor the health of the DPS as a detection observer on the basis of the nonlinear PDE representation of the system and by utilizing only the measured output vector. By taking the difference between measured and estimated outputs, a residual signal is generated for fault detection. If the detection residual exceeds a predefined threshold, a fault is claimed to be active. Once an actuator or a sensor fault is detected, an appropriate fault parameter update law is developed to learn the fault dynamics online with the help of an additional measurement. Later, an explicit formula is introduced to estimate the time-to-failure in the presence of an actuator/sensor fault by utilizing the limiting values of the output vector along with the estimated fault parameter vector. Eventually, the effectiveness of the proposed detection and prediction framework is demonstrated on a nonlinear process.
Quantum-chemical Investigation of Substituted s-Tetrazine Derivatives as Energetic Materials
Vikas D. Ghule,Radhakrishnan Sarangapani,Pandurang. M. Jadhav,Surya. P. Tewari 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.2
s-Tetrazine is the essential candidate of many energetic compounds due to its high nitrogen content, enthalpy of formation and thermal stability. The present study explores the design of s-tetrazine derivatives in which different -NO2, -NH2 and -N3 substituted azoles are attached to the tetrazine ring via C-N linkage. The density functional theory (DFT) is used to predict the geometries, heats of formation (HOFs) and other energetic properties. The predicted results show that azide group plays a very important role in increasing HOF values of the s-tetrazine derivatives. The densities for designed molecules were predicted by using the crystal packing calculations. The introduction of -NO2 group improves the density as compared to -N3, and -NH2 groups and hence the detonation performance. Bond dissociation energy analysis and insensitivity correlations revealed that amino derivatives are better candidates considering insensitivity and stability.
Decentralized Neural Network-based Excitation Control of Large-scale Power Systems
Wenxin Liu,Jagannathan Sarangapani,Ganesh K. Venayagamoorthy,Li Liu,Donald C. Wunsch II,Mariesa L. Crow,David A. Cartes 대한전기학회 2007 International Journal of Control, Automation, and Vol.5 No.5
This paper presents a neural network based decentralized excitation controller design for large-scale power systems. The proposed controller design considers not only the dynamics of generators but also the algebraic constraints of the power flow equations. The control signals are calculated using only local signals. The transient stability and the coordination of the subsystem control activities are guaranteed through rigorous stability analysis. Neural networks in the controller design are used to approximate the unknown/imprecise dynamics of the local power system and the interconnections. All signals in the closed loop system are guaranteed to be uniformly ultimately bounded. To evaluate its performance, the proposed controller design is compared with conventional controllers optimized using particle swarm optimization. Simulations with a three-machine power system under different disturbances demonstrate the effectiveness of the proposed controller design.
Gadegoni, Hemalatha,Manda, Sarangapani,Rangu, Shivaprasad Korean Chemical Society 2013 대한화학회지 Vol.57 No.2
A series of some novel 2-[5-(substituted phenyl)-[1,3,4]oxadiazol-2-yl]-benzoxazoles were synthesized by using benzoxazole-2-carboxylic acid on reaction with thionyl chloride in presence of ethanol solvent at room temperature gave benzoxazole-2-carbonyl chloride, which is turned into benzoxazole-2-carboxylic acid hydrazide on reaction with hydrazine hydrate in ethanol solvent under reflux. The subsequent treatment of benzoxazole-2-carboxylic acid hydrazide with an appropriate aromatic carboxylic acid in presence of polyphosparic acid under reflux afforded the title compounds. The chemical structures of the newly synthesized compounds were elucidated by their IR, $^1H$ NMR and Mass spectral data analysis. Further the compounds are used to find out their ability towards anti microbial and nematicidal activity.