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Submicron Size Patterned Nickel Soft Lithographic Masters Using Aluminium Template  [PDF]
T. Prakash
Soft Nanoscience Letters (SNL) , 2011, DOI: 10.4236/snl.2011.12007
Abstract: Nickel masters are widely used to produce surface relief grating like patterned antireflection coatings of polysiloxane material by simple embossing process. In the present work, patterned nickel master was prepared by using aluminium template, which is a foil peeled off from the commercial compact disk. Nickel was deposited using Watts nickel bath by pulsed electrodeposition for different relaxation times on patterned aluminium template. The deposition led to the transfer of patterns of aluminium replica to the nickel deposit. After deposition, the aluminium template was etched out chemically. Observation under an optical microscope showed that the obtained pattern was highly homogenous only for Ton = 0.1 ms, Toff = 0.9 ms duty cycles as compared with other ‘on’ and ‘off’ times of pulse cycles. This simple single step cost effective nickel master can serve as stamps for the subsequent embossing process. The preparation conditions and its salient features are discussed in this paper in detail.
Advances in Modeling and Simulation of Biomass Pyrolysis
N. Prakash,T. Karunanithi
Asian Journal of Scientific Research , 2009,
Abstract: The various aspects of modeling and simulation work carried out so far in biomass pyrolysis since 1946 have been extensively reviewed in the present study. Biomass pyrolysis, one of the few non conventional energy routes, is highly promising and capable of handling the current energy crisis successfully for the present and in the near future. Pyrolysis as a stand alone or as the core of biomass gasification process is complex in nature, the understanding and knowledge of this multifaceted phenomenon can heavily influence the efficiency and effectiveness of the whole gasification process. Even though, the modeling of biomass pyrolysis process was initiated during 1940`s gradual changes, improvements and alternates have been carried out throughout these years. All these years, various modeling approaches were adopted, different kinetic schemes were proposed, diverse numerical schemes were followed and range of parameters were implemented, all these have developed a baffling picture over the subject. The complexity of the process, as such the large number of components involved in the intermediates and end products; the dependency of the process over numerous parameters namely the temperature, space and time dependent physical, thermodynamic and transport properties, the particle shape, size, shrinkage factors and moisture content all these justify even today the necessity and requirement of research for further improvement and enrichment in the modeling and simulation fronts of this process. This study sums up the work carried out in literature on modeling and simulation of wood pyrolysis and suggests new research directions and approaches necessarily to be made up in future.
Fuzzy Based Constant Frequency-Unified Power Quality Conditioner
P. Jeno Paul,T. Ruban Deva Prakash
International Journal of Electrical and Power Engineering , 2012, DOI: 10.3923/ijepe.2011.108.115
Abstract: The aim of this study is to maintain the constant frequency in the utility using constant frequency unified power quality conditioner with fuzzy logic controller. A Constant Frequency Unified Power Quality Conditioning system (CF-UPQC) consists of a Unified Power Quality Conditioner (UPQC) and a matrix converter based frequency changer. UPQC is a combination of series active and shunt active filter. The series active filter and shunt active filters are used to compensate the voltage, current imbalance and harmonics. Frequency converter (matrix converter) is used to regulate the supply frequency when it varies beyond the power quality limit. The performance of the CF-UPQC is compared with fuzzy controller against conventional controller.
ANN Based Constant Frequency-Unified Power Quality Conditioner
P. Jeno Paul,T. Ruban Deva Prakash
Journal of Engineering and Applied Sciences , 2012, DOI: 10.3923/jeasci.2011.250.257
Abstract: The aim of this study is to maintain the constant frequency in the utility using constant frequency unified power quality conditioner with (Artificial Neural Network) ANN controller. A Constant Frequency Unified Power Quality Conditioning system (CF-UPQC) consists of a Unified Power Quality Conditioner (UPQC) and a matrix converter based frequency changer. UPQC is a combination of series active and shunt active filter. The series active filter and shunt active filters are used to compensate the voltage, current imbalance and harmonics. Frequency converter (matrix converter) is used to regulate the supply frequency when it varies beyond the power quality limit. The performance of the CF-UPQC is compared with ANN controller against conventional controller.
Performance Analysis of FACTS Controllers
T. Ruban Deva Prakash,N. Kesavan Nair
Journal of Engineering and Applied Sciences , 2012,
Abstract: The characteristics of FACTS controllers such as Fixed Capacitor- Thyristor Controlled Reactor (FC-TCR) Thyristor Controlled Voltage Regulator (TCVR) and Unified Power Flow Controller (UPFC) used for reactive power compensation in a transmission network are analyzed and the operation and simulation results are presented in this stduy. The control strategy for Real and Reactive powers of the transmission line using FC-TCR and UPFC and the voltage regulation using TCVR are described. In case of FC-TCR, the control is achieved by controlling the current through the TC reactor by varying the phase of the thyristor switch. In TCVR system, the power flow in the line is controlled by voltage regulation method. Thus, by voltage boosting in the transmission line, the power flow in the line is increased. This method uses thyristor based control and thus overcomes the difficulties of a conventional type on-load tap changer. The control in case of UPFC is obtained by replacing the traditional UPFC consisting of shunt converter and series converter with a current source and a voltage source model. The reactive power supplied to the load can be increased by increasing the magnitude of shunt current. The power factor can be increased by increasing the angle of injected voltage. The circuit models of FC-TCR, TCVR and UPFC systems are developed and the respective systems are simulated successfully using these models. The simulation results are presented to demonstrate the performance of the controllers
A Robust Control Strategy for Upfc to Improve Transient Stability Using Fuzzy Bang-Bang Control
T. Ruban Deva Prakash,N. Kesavan Nair
International Journal of Electrical and Power Engineering , 2012,
Abstract: Unified Power Flow Controller (UPFC) has been widely used to enhance damping of power swings. The control strategy adopted to mitigate power system oscillations in an effective and robust manner is the key issue. Various control methods used to improve the transient stability based on optimal parameters, state variables and injection model were studied. A scheme based on fuzzy bang-bang control is proposed for UPFC in this paper. Using Fuzzy Logic Control (FLC) based on bang-bang control; the UPFC will contribute to the damping of power swings without deteriorating the effect of the other Power Oscillation Damping (POD) devices. The damping effect is robust with respect to loading condition, fault location and network structure. Furthermore, the control inputs are based on rotor-angle signals that are estimated from voltage and power measurements. The FLC design is based on Lyapunov function analysis and is simulated on a single generator power system model. Numerical simulations show that the performance of controller is effective for both single-phase and three-phase fault. This single generator approach can be extended to multi-generator systems.
Voltage Sag Mitigation in Multi-Line Transmission System Using GUPFC
T. Ruban Deva Prakash,N. Kesavan Nair
International Journal of Electrical and Power Engineering , 2012,
Abstract: Voltage sag is one of the most severe power quality disturbances to be dealt with by the industrial sector, as it can cause severe process disruptions and result in substantial economic loss. One of the main factors which limit capabilities of Dynamic Voltage Restorer (DVR) in compensating long-duration voltage sags is the amount of stored energy within the restorer. In order to overcome this limitation, Inter-line Dynamic Voltage Restorer (IDVR) has been proposed where two DVRs each compensating a transmission line by series voltage injection, connected with common dc-link. When one DVR compensates voltage sag, the other DVR of the IDVR replenish the dc-link energy storage. This IDVR works efficiently when the lines under consideration are connected with two different grid substations, as it is reasonable to assume that voltage sag in one line would have lesser impact on the other line. But in case when the lines are connected with same grid substation and feeding two different sensitive loads in an industrial park, voltage sag in one line affects the voltage profile of other lines. Under the above circumstances, long duration voltage sags cannot be mitigated by IDVR due to insufficient energy storage in dc-link. This study proposes a voltage sag compensator based on Generalized Unified Power Flow Controller (GUPFC), which comprises of three voltage-sourced converter modules sharing a common dc link. Two voltage-sourced converter modules connected in series with the lines, which compensates voltage sag and a third shunt converter module maintains bus voltage and replenish the common dc-link energy storage. The control strategy for power flow control of shunt converter and sag compensation control of series converters are discussed in detail. Adjustable carrier PWM is used for generating switching pulses. The simulation model of GUPFC is developed in this study. The salient advantages of the proposed method are compensating long duration deeper voltage sags, reduction in size of dc-link capacitor and simultaneous voltage sag compensation in all lines. Simulation results presented for a simple system under three-phase voltage sag of 40% and -20 phase angle jump demonstrates the efficiency of the proposed system.
Neuro-Fuzzy Based Constant Frequency-Unified Power Quality Conditioner
P. Jeno Paul,T. Ruban Deva Prakash
International Journal of Systems Signal Control and Engineering Application , 2012, DOI: 10.3923/ijssceapp.2011.10.17
Abstract: The aim of this study is to maintain the constant frequency in the utility using constant frequency unified power quality conditioner with neuro-fuzzy logic controller. A Constant Frequency Unified Power Quality Conditioning system (CF-UPQC) consists of a Unified Power Quality Conditioner (UPQC) and a matrix converter based frequency changer. UPQC is a combination of series active and shunt active filter. The series active filter and shunt active filters are used to compensate the voltage, current imbalance and harmonics. Frequency converter (matrix converter) is used to regulate the supply frequency when it varies beyond the power quality limit. The performance of the CF-UPQC is compared with neuro-fuzzy controller against conventional controller.
Nonlinear Oscillation of FGM plates under Aerodynamic Load
M. K. Singha,T. Prakash,M. Ganapathi
Lecture Notes in Engineering and Computer Science , 2010,
Abstract:
Effect of DC bias on electrical conductivity of nanocrystalline α-CuSCN
T. Prakash,S. Ramasamy,B. S. Murty
AIP Advances , 2011, DOI: 10.1063/1.3583601
Abstract: The grain boundary space charge depletion layer in nanocrystalline alpha phase CuSCN is investigated by studying electrical properties using impedance spectroscopic analysis in frequency domain. The measurements were performed at room temperature in wide frequency range 1 Hz to 1 MHz under various DC bias applied voltages ranges from 0 V to -2.1 V. The effect of bias on grain and grain boundary contribution electrical conductivity has been investigated by equivalent circuit model using non-linear least squares (NLLS) fitting of the impedance data. Three order of magnitude variation of grain boundary conductivity was observed for varying 0 V to -2.1 V. Variations in the σac clearly elucidate the DC bias is playing crucial role on grain boundary double Schottky barriers of nanocrystalline α-CuSCN.
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