Electrical Engineering

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Shiv Nadar University

In this paper we propose an adaptive channel estimation scheme for Amplify and Forward (AF) two-way relay systems with frequency selective and fast varying channels. The modulation used is Orthogonal Frequency Division Multiplexing (OFDM). This adaptive filter is called Block Fast Array Multichannel 2D Recursive Least Square (BFAM 2D-RLS) filter. The complexity of this adaptive filter is comparable to that of Least Mean Square (LMS) algorithm while maintaining similar convergence rate as that of the standard Recursive Least Mean Square (RLS) algorithm. Computer simulation using Matlab is performed to analyse the performance of BFAM 2D-RLS filter in estimating fast varying Vehicular-A (Veh-A) channel. The results obtained is compared with slow varying channels. © 2015 IEEE.

World University root node

(SoE) School of Engineering

Proceedings - 2015 Advances in Wireless and Optical Communications, RTUWO 2015

BFAM 2D-RLS channel estimation for frequency selective environment in two-way relay

This paper studies the use of light-emitting diode (LED) as an excitation source for photothermal lock-in experiments, and investigates the energy absorption efficiency and signal-to-noise ratio of the established setup. Existing lock-in excitation sources usually use high power (in the range of kilowatt) halogen lamps. The present LED excitation source has an advantage of low power consumption making the setup much more energy efficient. Another advantage of LED in this paper is their low infrared (IR) content, in contrast to halogen lamps, the IR content gets reflected into the IR camera, and leads to an unpredicted change in phase image in lock-in thermography. © 2015 IEEE.

IEEE Sensors Journal

Characterization and Energy Absorption Efficiency Determination of LED as an Effective Photothermal Excitation Source in Lock-In Thermography

A technique for wavelength measurement of microwaves is demonstrated. The wavelength is obtained from an interference pattern monitored by an IR Camera. The data captured by the camera is stored in a computer attached to it. This data is then processed for wavelength calculation. In order to show the utility of the above technique, two cases are demonstrated: Case (1) Interference pattern of two patch antennas each radiating at 8 GHz. Case (2) Interference pattern from a single antenna, radiating at 12 Ghz, kept in front of a metallic sheet with two slits. The simulation is carried in CST Microwave Studio software. A good agreement between simulation and experimental results is seen. © 2015 IEEE.

2nd International Conference on Signal Processing and Integrated Networks, SPIN 2015

Infrared thermography for determination of wavelength of microwave signals from interference pattern

In this paper, we evaluate and compare the performances of Viterbi decoding schemes based on soft decision and hard decisions, with results applicable to the Digital Video Broadcast-Terrrestial (DVB-T) standard. The standard suggests that the BER ≤ 2 × 10-4 at the decoder output is good enough for the quasi error-free condition. We assume that the channel state information (CSI) of all sub-carriers are available at the receiver at all times. The multipath fading is assumed to be Rayleigh type. Simulation results confirm the advantage of using soft-decision decoding over the hard-decision type. Approximate Eb/N0 gains in the range 3-4.5 dB are reported for the different choices of code rates and OFDM transmission modes available in the standard.

11th IEEE India Conference: Emerging Trends and Innovation in Technology, INDICON 2014

A simulation study of performance of joint soft demapping-viterbi decoding in DVB-T system

Markov games can be used as a platform to deal with exogenous disturbances and parametric variations. In this work an attempt has been made to achieve a superior performance with fuzzy Markov game based control by hybridizing two game theory based approaches of 'fictitious play' and 'minimax'. The work attempts a 'safe yet consistent' Markov game controller which advocates a minimax policy during the startup control stages and later moves to a more enterprising policy based on stochastic fictitious play. The proposed controller addresses continuous state action space problems wherein we use fuzzy inference system as a universal approximator for generalization with a proportional derivative control in the nested position tracking loop. The proposed controller is simulated on a two link robot and its performance compared against fuzzy Markov game control and fuzzy Q control. Simulation results elucidate the fact that proposed control scheme leads to an improved controller with lower tracking error and torque requirements. © 2014 IEEE.

Proceedings - 2014 3rd International Conference on Reliability, Infocom Technologies and Optimization: Trends and Future Directions, ICRITO 2014

Fictitious play based Markov game control for robotic arm manipulator

Photovoltaic (PV) arrays are susceptible to large amounts of power losses due to partial shading on the array. The power-voltage characteristics of partially shaded array contain multiple local maxima and global maximum power point (GMPP) is one of them. The losses in the PV array depend both, the shadow shape and physical location of the shaded modules. This paper presents an innovative approach to arrange the modules in the array in such a way that there is an increase of power generation of array under partial shading condition. In this approach, without changing the electrical connection of the modules, the physical locations of the modules in Total Crossed Tired (TCT) structure are rearranged. The modules are rearranged in such a way that the shading effect is distributed over the array, and it reduces the shading modules in the same row. The power generation of array with TCT and proposed configuration is compared in this paper. It is demonstrated that the power generation of array with proposed configuration is enhanced under different shading pattern. © 2014 IEEE.

2014 18th National Power Systems Conference, NPSC 2014

Improvement in the power generation of a PV array under partial shading conditions

During the winding process of a transformer, a residual strain is induced in its windings conductors. In this paper, the effect of the strain on the mechanical strength of transformer windings under the worst case condition of the short circuit has been investigated. The distribution of the residual strain in the conductors during its winding process has been determined analytically. The strain induced in the conductors under the action of radial short-circuit forces has been computed. The two strains are then added to obtain a resulting strain. By using the Ramberg-Osgood stress-strain relation of the conductor (copper) material, resulting stress is determined. A case study has been given where the presence of residual strain in the conductors of a power transformer has been taken into account for determining its mechanical strength under the worst case condition of short circuit. © 2015 IEEE.

IEEE Transactions on Power Delivery

An investigation of winding curvature effect on the mechanical strength of transformer windings

The paper presents frequency modulated thermal wave imaging (FMTWI) as a fast and efficient non-contact technique for in-plane thermal characterization of thin plate nanomaterials. A novel excitation signal in the form of an up-chirp is applied and the thermal response is monitored using an infrared (IR) thermography based temperature sensing system. The in-plane thermal diffusivity of any sample can be measured using the multiple phase information extracted from a single run of the experiment. This feature provides a time efficient approach for thermal measurements using infrared thermography techniques. The theoretical background and experimental details of the technique are discussed, with practical measurement of thermal diffusivity of an empty anodic alumina (AAO) template in direction perpendicular to the nanochannel axis, in support. © 2014 Elsevier B.V. All rights reserved.

Infrared Physics and Technology

Frequency modulated infrared imaging for thermal characterization of nanomaterials

One-dimensional nanostructures such as Ni and Co nanowires (NWs) show anisotropic thermal properties in a direction parallel and perpendicular to the NW axis. Thermal diffusivity of Ni and Co NWs embedded in a 100-nm pore anodic alumina (AAO) template has been measured in a direction perpendicular to the NW axis, using an infrared thermography-based non-contact approach. The measured thermal diffusivity values in the radial direction are 0.728×10 -6 and 0.732×10-6 m2s-1, respectively, for the Ni and Co nanocomposites. The changes in the thermal diffusivity of the synthesized NWs alone were estimated using a first-order lower bound model (FOLBM). A nearly seven- and sixfold reduction, respectively, of thermal diffusivity in a direction perpendicular to the NW axis is estimated for the synthesized Ni and Co NWs. © 2014 Elsevier Ltd.

Journal of Physics and Chemistry of Solids

Thermal diffusivity of electrodeposited Ni and Co nanowires using infrared thermography

Improvement of energy efficiency of photovoltaic (PV) system is needed to fulfill the energy crises. The power generation of PV array decreases due to partial shading occurs on the PV array. In partial shading condition, the PV modules of the array receive different intensity of solar irradiation and hence mismatch losses occurs between the modules. Thus the power-voltage characteristics of PV arrays contain multiple local maxima and one of them is a global maximum power point (GMPP). This paper presents an novel approach to arrange the physical position of modules in Total Cross Tied (TCT) configuration, without changing the electrical connection of the modules in the array. In this approach, the arrangement of PV modules of TCT configuration is done in such a way that the shading effect is distributed over the entire array, and hence it reduces the multiple local maxima in power-voltage characteristics of the PV array. Thus the tracking of GMPP in the present approach is simpler. In this paper, the power generation of array with TCT and proposed configuration is compared with theoretical and MATLAB simulation results. It is investigated that the power generation of PV array with proposed configuration is enhanced under different shading patterns. © 2014 IEEE.