Department of Electrical Engineering

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This paper presents the control of a gas metal arc welding (GMAW) system using one of the higher order sliding mode control algorithms, the super twisting controller, which is a continuous control and a superior control with its extreme robustness property. A nonlinear multi input multi output (MIMO) system model has been considered here for the design of the super-twisting controllers. The control inputs chosen are, the open circuit voltage and the wire feed speed which are used to control the current and arc length of the system. The performance analysis of the controllers are studied in the presence of wide variations of model parameter uncertainties. The simulation results are presented to illustrate the efficiency of the controller used. © 2013 IEEE.

World University root node

Proceedings of the IEEE International Conference on Industrial Technology

Robust nonlinear control of GMAW systems-a higher order sliding mode approach

In this paper, stabilization of a chain of fractional-order integrators is attempted. The stability is proved using contraction analysis. A numerical example is presented to illustrate the proposed method. © 2013 The authors. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

Fulltext

IMA Journal of Mathematical Control and Information

Stabilization of a fractional-order chain of integrators: A contraction-based approach

The central problem in reactor analysis is the determination of the spatial flux and power distribution in the reactor core under steady state as well as transient operating conditions. There is, however, a considerable variation in the degree of accuracy and spatial details of the power distribution required in different facets of reactor analysis and design. Basically, the behavior of neutrons in a nuclear reactor is adequately described by the time-dependent Boltzmann transport equation [24, 38]. However, numerical solutions of the coupled time-dependent transport and delayed neutron precursors’ equations for reactor kinetics problems of practical interest are prohibitively difficult. © 2013, Springer-Verlag Berlin Heidelberg.

Lecture Notes in Control and Information Sciences

Multipoint kinetics modeling of large nuclear reactors

In this paper design of reduced order switching function for a discrete-time uncertain nonminimum phase system in special coordinate basis form is proposed. The sliding mode control with this method guarantees the asymptotic stability of all states of system in presence matched disturbance. This problem is further extended to the tracking problem of discrete time uncertain nonminimum phase systems. The results obtained with reduced order sliding surface design are compared with the results of full order sliding surface. © IFAC.

IFAC Proceedings Volumes (IFAC-PapersOnline)

Discrete-time sliding mode tracking control for NMP systems using reduced order switching function

The substrate effect on InN nanostructures grown by droplet epitaxy has been studied. InN nanostructures were fabricated on Si(111), silicon nitride/Si(111), AlN/Si(111) and Ge(100) substrates by droplet epitaxy using an RF plasma nitrogen source. The morphologies of InN nanostructures were investigated by field emission scanning electron microscopy (FESEM). The chemical bonding configurations of InN nanostructures were examined by x-ray photoelectron spectroscopy (XPS). Photoluminescence spectrum slightly blue shifted compared to the bulk InN, indicating a strong Burstein-Moss effect due to the presence of high electron concentration in the InN dots (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Physica Status Solidi (C) Current Topics in Solid State Physics

Substrate impact on the growth of InN nanostructures by droplet epitaxy

The structural and optical properties of semipolar (1 1 -2 2) GaN grown on m-plane (1 0 -1 0) sapphire substrates by molecular beam epitaxy were investigated. An inplane orientation relationship was found to be [1 -1 0 0] GaN || [1 2-1 0] sapphire and [-1 -1 2 3] GaN || [0 0 0 1] sapphire for semipolar GaN on m-plane sapphire substrates. The near band emission (NBE) was found at 3.432 eV, which is slightly blue shifted compared to the bulk GaN. The Raman E2 (high) peak position observed at 569.1 cm-1, which indicates that film is compressively strained. Schottky barrier height (φb) and the ideality factor (η) for the Au/ semipolar GaN Schottky diode found to be 0.55 eV and 2.11, respectively obtained from the TE model. © 2013 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Molecular beam epitaxial growth of (1 1 -2 2) GaN on m-plane sapphire

Electroplated copper thin films have been extensively used for interconnections in semiconductor devices. In this paper, electroplating of copper has been investigated to study the dependency of plated film thickness, current efficiency and sheet resistivity on current density. Copper film is electroplated on gold seed layer for via filling using different current densities varying from 10mA/cm2 to 70mA/cm2 at constant temperature (40°C). Annealing analysis for plated thick film is done at 200°C for 30 minutes. Surface roughness reduces along with resistivity with annealing.

Technical Proceedings of the 2013 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2013

Experimental study on sheet resistivity and thickness measurement in copper electroplating

Random jitter (RJ) estimation based on Tail Fit algorithm are generally inaccurate in presence of deterministic components like the presence of sinusoidal jitter (SJ) and duty cycle distortion (DCD). Addition of deterministic jitter changes the standard deviation of the tail region of resulting jitter probability density function. A new methodology for random jitter estimation in presence of sinusoidal jitter and duty cycle distortion is presented. The method involves calculation of mathematical correction factor, which are derived and used to calculate the precise value of random jitter. The proposed methodology is validated by inducing known jitter sources in real channel simulator of ADS from Agilent. © 2013 IEEE.

2013 IEEE 22nd Conference on Electrical Performance of Electronic Packaging and Systems, EPEPS 2013

Mitigating the impact of sinusoidal jitter and duty cycle distortion on random jitter estimation by Tailfit algorithm

In this paper, the variation of unloaded Quality factor QU of a substrate integrated waveguide (SIW) resonator with the substrate parameters is presented. It is observed that the QU strongly depends on substrate thickness, dielectric constant and loss tangent values. QU of a SIW resonator is also compared with that of a conventional rectangular air filled waveguide resonator and also that of a microstrip resonator. The graphical results shown in this paper can be used as a guideline to choose a proper wave guiding structure or an appropriate substrate for SIW application especially where insertion loss is an important issue. © 2013 IEEE.

2013 International Conference on Microwave and Photonics, ICMAP 2013

Unloaded quality factor of a substrate integrated waveguide resonator and its variation with the substrate parameters

The paper presents the electrical and thermo-mechanical design of single stage beam recovery system for 120 GHz, 1 MW gyrotron. The electrical study shows that the cylindrical shape single stage beam recovery system enhances the efficiency by 66.26%. The maximum power deposited to collector in depressed collector operation is 0.48 MW for electronic efficiency, 30% and 1.44 MW for DC electron beam. The thermo-mechanical analysis has been performed to evaluate the water cooling system. The cooling system has capability of accommodating a peak wall loading, 0.9 kW/cm2 at flow rate of 1500 l/min for safe operating time, 60 ms. Further, a high voltage analysis is also carried out to appraise the electric field distribution in the collector. © 2013 Elsevier B.V.