Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

In rate-adaptive orthogonal frequency division multiplexing (OFDM) systems, limited feedback schemes are essential to reduce the number of subchannels for which the channel state information is fed back by the users. For the practically important best-M scheme, in which each user feeds back only its M strongest subchannels and their indices to the base station (BS), we derive a throughput-optimal rate adaptation policy that enables the BS to assign rates to the subchannels of every user. We present it in closed-form for the widely used exponential correlation model. The novelty of the policy lies in its exploitation of the structure of the information fed back by the best-M scheme and the correlation among subchannel gains. We also present a near-optimal, lower computational complexity approach. In effect, our approach facilitates rate adaptation and scheduling by the BS even on subchannels that are not fed back by a user due to feedback constraints. For various schedulers, we show that it improves the downlink throughput compared to several conventional approaches, without requiring any additional feedback. © 2016 IEEE.

Department of Electrical Engineering

World University root node

2016 IEEE International Conference on Communications, ICC 2016

Throughput-optimal rate adaptation for best-M feedback in OFDM systems

Time-variations in wireless channels affect opportunistic selection in a multi-node wireless system in two ways. First, the selected node can become sub-optimal by the time data transmission commences. Second, the channel changes during data transmission. We develop a comprehensive and tractable analytical framework that accurately accounts for both these effects. It differs from the extensive existing literature that primarily focuses on time-variations until the data transmission starts. We first develop a novel concept of a time-invariant effective signal-to-noise ratio (TIESNR), which tractably and accurately captures the time-variations during the data transmission phase with partial channel state information available at the receiver. Thereafter, we model the joint distribution of the signal-to-noise ratio at the time of selection and TIESNR during the data transmission and analyze the average packet error rate (PER). Extensive numerical results verify the accuracy of each step of our approach and show that ignoring the correlated time-variations during the data transmission phase can significantly underestimate the average PER. © 2016 IEEE.

A tractable analytical framework for evaluating opportunistic selection in time-varying channels

This paper presents tracking control laws for two different objectives of a nonholonomic system - a spherical robot - using a geometric approach. The first control law addresses orientation tracking using a modified trace potential function. The second law addresses contact position tracking using a right transport map for the angular velocity error. A special case of this is position and reduced orientation stabilization. Both control laws are coordinate free. The performance of the feedback control laws are demonstrated through simulations. © 2016

IFAC-PapersOnLine

Geometric tracking control for a nonholonomic system: a spherical robot

For real-Time sparse systems identification applications, Proportionate-Type Least Mean Square (Pt-LMS) algorithms are often preferred to their normalized counterparts (Pt- NLMS) due to lower computational complexity of the former algorithms. In this paper, we present the convergence analysis of Pt-LMS algorithms. Without any assumptions on input, both first and second order convergence analysis are carried out and new convergence bounds are obtained. In particular, it establishes the universality of the steady-state mean square deviation. Detailed simulation results are presented to validate the analytical results.

Signal Processing - Algorithms, Architectures, Arrangements, and Applications Conference Proceedings, SPA

Performance analysis of proportionate-Type LMS algorithms

This paper focuses on Voltage Fed Dual Active Bridge (VF-DAB) bidirectional DC-DC converter modules connected Input Parallel and Output Parallel (IPOP) configuration. Modularity or parallel operation of the bidirectional DC-DC converters for energy storage application is not just an economic solution for increasing the power transfer capability, but also provides several advantages such as redundancy, reduced design cost and hot swap feature of faulty module. In this paper, an interleaved VF-DAB with phase-shedding operation at light loads are proposed for interfacing energy storage devices to a common DC bus. A modification in the conventional active current sharing technique for parallel operated converters is proposed to implement phase shedding and phase adding operation. A 12 kW interleaved IPOP based DAB converter is proposed and simulated to validate the claims. © 2015 IEEE.

INTELEC, International Telecommunications Energy Conference (Proceedings)

A new phase shedding and phase adding control scheme for interleaved DAB converter operating in IPOP configuration

Grinding nowadays is extensively used for machining of superalloys. Inconel 718 is a Ni-based superalloy which is known as difficult to grind material (DTG) due to its inherent properties like high hardness, high hot strength, severe strain hardening and low thermal conductivity. In the present work, grindability of Inconel 718 using conventional abrasive grinding wheels has been experimentally explored. Ground surfaces have been characterized after grinding with silicon carbide (SiC) and alumina (Al2O3) wheels under dry condition. Surface integrity of the ground product has been studied using surface characterization techniques like Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Further, the surface behavior of the ground surface has been investigated using microscopic images, micro-hardness tests, and surface roughness measurements. The major conclusion of the present work is that Inconel 718 can be ground more efficiently using alumina grinding wheels compared to the SiC grinding wheel. In the case of SiC wheel, it has been found that the severe attritious wear of the wheel took place primarily due to the chemical reaction between SiC grits and workpiece material at a higher grinding temperature. The mechanism for such attritious wear has been studied, and it appears to be a dissociation of SiC at higher temperature. © 2015 The Society of Manufacturing Engineers.

Department of Mechanical Engineering

Journal of Manufacturing Processes

An investigation on surface burn during grinding of Inconel 718

This paper presents a radio frequency micro-electromechanical system (RF MEMS) based 3-bit phase shifter using MEMS single-pole-eight-throw (SP8T) switches. Devices are fabricated on 635 μm alumina substrate utilizing on the coplanar waveguide (CPW) transmission line. Single switch dimensions are 0.14 × 0.23 mm2 which is much smaller than Si-on-insulator switches. The symmetric and compact SP8T switch is the primary building block of the 3-bit phase shifter. The SP8T switch results in isolation levels of 31-15 dB, return loss of 33-18 dB and insertion loss of 0.6-1.9 dB, respectively, at 26-40 GHz. Later, two SP8T switches are connected back to back to develop the 3-bit phase shifter using different delay lines at 35 GHz. Finally, the phase shifter provides average return loss of better than 14 dB and average insertion loss of 4.4 dB over the 34.75-35.25 GHz. Measured average phase error is less than 0.98° at 35 GHz. The total area of the fabricated 3-bit phase shifter is 5.95 mm2. SP8T switches are capable of handling 0.1-1 W of power up to 100 million cycles which is sufficient power handling capability for wireless communication systems. Reliability of the phase shifter is extensively characterized with different incident RF powers at room temperature (25°C) and discussed in detail. To the best of the authors' knowledge, this is the first reported MEMS 3-bit phase shifter in the literature that has used a minimum number of switching elements per phase state. © 2016 IOP Publishing Ltd.

Journal of Micromechanics and Microengineering

Ka-band reliable and compact 3-bit true-time-delay phase shifter using MEMS single-pole-eight-throw switching networks

This paper proposes a new forty nine level stacked inverter topology using low voltage devices for drives applications. The forty nine level inverter is developed by stacking three seventeen level inverters. The seventeen level inverter is developed by cascading a flying capacitor inverter and three H-Bridges. The inverter can operate with lower number of voltage levels if any of the H-Bridges fail. The capacitor voltage balancing in the inverter can be done irrespective of modulation index and load power factor. The topology is further modified to reduce the capacitor and switch count. Also, the inverter does not use any pulse width modulation between the different voltage levels. Therefore switching losses are reduced. In addition, since the switches need to block only lower voltages, MOSFETs can be used which will further improve the efficiency. An induction motor driven by this inverter using V/f control is simulated in MATLAB simulink and both steady state and transient results are presented. © 2016 IEEE.

IECON Proceedings (Industrial Electronics Conference)

A novel forty nine level stacked inverter topology using low voltage devices for drives

This work presents micro-electromechanical system (MEMS) based switches and phase shifters for transmit/receive module applications. All designs are implemented using coplanar waveguide (CPW) transmission line and fabricated on 635-μm alumina substrate using surface micromachining process. Different switching networks like series/shunt configuration, single-pole-double-throw (SPDT), single-pole-four-throw (SP4T), SP8T, SP9T and SP12T are presented for application in multi-bit digital phase shifters. One configuration of the 5-bit phase shifter demonstrates an average insertion loss of 2.65 dB in the 16.75 - 17.25 GHz band with a return loss better than 22 dB and average phase error less than 0.680 at 17 GHz. Total area of the fabricated 5-bit phase shifter is 13 mm2. © 2016 EuMA.

European Microwave Week 2016: "Microwaves Everywhere", EuMW 2016 - Conference Proceedings; 46th European Microwave Conference, EuMC 2016

Micromachined switches and phase shifters for transmit/receive module applications

A state-dependent jump linear system (SDJLS) is a particular type of stochastic switching system, where the transition rates or probabilities of the underlying random jump process depend on the state variable. In this paper, a continuous-time SDJLS subject to external disturbances with finite energy is considered. Regarding the underlying random jump process, the transition rates are assumed to have different values across different sets where the state of the system evolves. By evaluating the infinitesimal generator for the stochastic Lyapunov function of SDJLS, a state-feedback H∞ controller is synthesized that guarantees disturbance rejection while ensuring stochastic stability via solving a set of sufficient linear matrix inequalities. The overall approach is illustrated with a numerical example. © 2016 IEEE.