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.

&nbsp;

IIT Palakkad

This paper presents an automatic method for simultaneous detection and elimination of impulsive noises from audio signals. The method is based on the sparse signal decomposition (SSD) with overcomplete hybrid dictionary (OHD) matrix including impulse and sinusoidal waveforms derived from discrete impulse, sine and cosine functions, and 1-norm optimization algorithm. The SSD technique decomposes an audio signal into two parts: an approximation part including the sinusoidal components; and a detail part including the impulsive and background noise components. Results show that the impulse waveforms can adequately capture clicks, pops and record scratches in audio signals meanwhile the sinusoids of the OHD matrix can effectively capture sinusoidal components. For performance comparison purpose, four restoration methods are implemented based on the representation dictionaries, median filter, and signal dependent rank order mean techniques. The methods are validated using audio signals extracted from old archive Indian and English movies and standard music database. The quality of the restored audio signals is evaluated using both subjective quality and objective quality metrics. Results show that the proposed method effectively removes impulsive noises without degrading the perceived audio quality and its intelligibility as compared to the existing restoration methods. © 2017 IEEE.

Department of Electrical Engineering

World University root node

IEEE Region 10 Annual International Conference, Proceedings/TENCON

Elimination of impulsive disturbances from archive audio signals using sparse representation in mixed dictionaries

This paper presents the small-signal stability analysis of an 11-kW open-loop inverter-fed induction motor drive, including the effect of inverter dead-time. The analysis is carried out using an improved small-signal model of the drive that has been reported in literature recently, and is used to demonstrate small-signal instability in a higher-power-level motor. Through small-signal stability analysis, the region of oscillatory behaviour is identified on the voltage versus frequency plane (V–f plane), considering no-load. These predictions using the improved model are also compared against predictions of a standard model of an inverter-fed induction motor including dead-time effect. The oscillatory behaviour of the 11-kW motor drive is also studied through extensive time-domain numerical simulations and actual measurements over wide ranges of operating conditions. Both the simulation and experimental results confirm the validity of the predictions by the improved analytical model. Further, these results establish that the analysis is valid for both sine-triangle pulse-width modulation (PWM) and conventional space vector PWM. © 2017, Indian Academy of Sciences.

Fulltext

Sadhana - Academy Proceedings in Engineering Sciences

Theoretical prediction and experimental verification of light-load instability in a 11-kW open-loop induction motor drive

In this paper, a new space vector pulse width modulation method to extend the linear modulation range of a cascaded five level inverter topology with a single dc supply is presented. Using this method, the inverter can be controlled linearly and the peak phase fundamental output voltage of the inverter can be increased from 0.577 to 0.637Vdc without increasing the dc bus voltage and without exceeding the induction motor voltage rating. This new technique makes use of cascaded inverter pole voltage redundancy and property of the space vector structure for its operation. Using this, the induction motor drive can be operated till the full speed range (0-50 Hz) with the elimination of lower order harmonics in the phase voltage and phase current. The five-level topology presented in this paper is realized by cascading a two-level inverter and two full bridge modules with floating capacitors. The inverter topology and its operation for extending the modulation range is analyzed extensively. Simulation and experimental results for both steady-state and dynamic operating conditions are presented in this paper. © 2016 IEEE.

IEEE Transactions on Power Electronics

Extending the linear modulation range to the full base speed using a single DC-link multilevel inverter with capacitor-fed H-bridges for im drives

This paper presents a method for generating a multilevel dodecagonal voltage space vector structure using a single dc source for induction motor drives. Multilevel dodecagonal structure combines the advantages of both multilevel and dodecagonal structures and hence, generates low dv/dt phase voltage along with the elimination of fifth-and seventh-order harmonics over the entire modulation range. This eliminates low-order harmonic currents and prevents the generation of sixth-order torque ripple in the motor. The topology used requires only one dc source making four-quadrant operation of the drive system simpler compared to previously proposed multilevel topologies generating dodecagonal space vector structures. The topology used consists of a three-level flying capacitor (FC) inverter cascaded with a capacitor fed H-bridge. The FC inverter operates at a lower switching frequency and the low-order harmonics are eliminated by the switching action of the cascaded H-bridge inverter. The capacitors in the cascaded H-bridge modules are maintained at a substantially smaller voltage compared to the dc-link voltage and are inherently balanced during the pulsewidth modulation operation. This results in low switching loss, in the FC inverter as well as in the cascaded H-bridge inverter. Experimental results are included to validate the operation of the topology and modulation scheme presented in this paper.

Fifth-and Seventh-Order Harmonic Elimination with Multilevel Dodecagonal Voltage Space Vector Structure for im Drive Using a Single DC Source for the Full Speed Range

In machining process, friction between the chip-tool interface and the heat generation due to shearing action are important issues that govern the machining forces, tool life and surface quality of the product. Efficient cooling and lubrication can reduce the high amount of heat generated during machining. The cooling and lubrication depend on the wetting behavior of metal working fluid (MWF) on the tool surface. However, the relation between the key parameters which affect the MWF's wettability behavior on the cutting tool surface are not studied much, especially for the machining process. In this paper, an attempt has been made to understand the correlation between the spreading behavior, surface tension and surface energy of nano-Al2O3 based fluid added with different surfactants, on tungsten carbide (WC) cutting inserts (Ti-Al-N coated and uncoated) and Inconel 718. Further, machining experiments have been conducted using the nanofluid (NF) under minimum quantity cooling and lubrication (MQCL) mode. The results showed that the spreading parameter of NF varies linearly with the surface tension on cutting tool surfaces. The spreading parameter has been found to be more reliable, and a relevant parameter for describing the wetting behavior of NF on the tool surfaces. The machining results obtained in this study are explained in terms of the spreading coefficient, and the best wetting behavior has been observed when the non-ionic surfactant added NF is used on the uncoated tool surface. Consequently, machining experiments with Inconel 718 using the aforementioned NF showed a reduction in coefficient of friction, tool wear, and chip curling radius. © 2017 Elsevier B.V.

Department of Mechanical Engineering

Journal of Materials Processing Technology

Spreadability studies of metal working fluids on tool surface and its impact on minimum amount cooling and lubrication turning

This study presents a variational mode decomposition (VMD)-based approach to analyse wide-area (WA) measurements based signals. The commonly used empirical mode decomposition (EMD) has limitations such as sensitivity to noise and sampling rate. However, VMD is an entirely non-recursive algorithm, where the modes are extracted concurrently. These modes help in extracting dynamic patterns of different power system disturbances. The performance of the proposed scheme is extensively validated on the IEEE-39 bus New England test system. The modes generated and the frequency deviation contours of the disturbances including generation loss, fault and line outage are assessed using VMD and the results provide improved performance in terms of decomposition quality compared with the existing EMD technique. Furthermore, a data-mining model known as decision tree is used to classify different power system disturbances based on intrinsic mode functions generated through VMD. The suggested method shows improved decomposition quality and classification accuracy. Thus, the proposed scheme is a potential candidate for improving WA situational awareness along with a post-mortem analysis of real events occurring in a power system. © The Institution of Engineering and Technology.

IET Generation, Transmission and Distribution

Variational mode decomposition-based power system disturbance assessment to enhance WA situational awareness and post-mortem analysis

Considering high throughput values as specified by modern video processing standards, Scalable Video Coding (SVC) systems intended for such standards are generally implemented by means of dedicated hardware. However, the high computational complexity associated with the current Compressed Sensing (CS) based video coding schemes makes their hardware realization considerably challenging. In this paper, we present a novel CS based SVC framework that is amenable to real-time VLSI implementation. At the encoder, after applying the Three-Dimensional Discrete Wavelet Transform (3-D DWT) on the input video frames, a novel Adaptive Measurement Scheme (AMS) in CS is introduced, which is applied on the high frequency sub-bands of the 3-D DWT frames. The proposed AMS along with 3-D DWT not only achieves scalability and better compression ratio, but also reduces the overall computational complexity of the system. We have also proposed an Enhanced Approximate Message Passing (EAMP) algorithm to reconstruct the high frequency sub-bands from the CS measurements at the decoder. The proposed EAMP procedure combines the benefits of Approximate Message Passing (AMP) and Iterative Hard Thresholding (IHT) algorithms thereby simultaneously achieving sparsity measurement trade-off and good reconstruction quality. We have carried out the detailed complexity analysis and simulations to demonstrate the superiority of the proposed framework over the existing schemes. © 2017 Elsevier B.V.

Signal Processing: Image Communication

A novel framework for compressed sensing based scalable video coding

This study addresses a stochastic model predictive tracking problem for linear parameter-varying (LPV) systems described by affine parameter-dependent state-space representations and additive stochastic uncertainties. The reference trajectory is considered as a piecewise constant signal and assumed to be known at all time instants. To obtain prediction equations, the scheduling signal is usually assumed to be constant or its variation is assumed to belong to a convex set. In this study, the underlying scheduling signal is given a stochastic description during the prediction horizon, which aims to overcome the shortcomings of the two former characterisations, namely restrictiveness and conservativeness. Hence, the overall LPV system dynamics consists of additive and multiplicative noise terms up to second order. Due to the presence of stochastic disturbances, probabilistic state constraints are considered. Since the disturbances make the computation of prediction dynamics difficult, augmented state prediction dynamics are considered, by which, feasibility of probabilistic constraints and closed-loop stability are addressed. The overall approach is illustrated using a tank system model. © The Institution of Engineering and Technology 2017.

IET Control Theory and Applications

Stochastic model predictive tracking of piecewise constant references for LPV systems

A novel readout circuit for interfacing single element resistive sensors is presented in this paper. The proposed scheme is based on a new relaxation oscillator (RO). The RO, along with a timer counter provides a digital output proportional to the resistance of the sensor. The output characteristic of most of the existing readout circuits for resistive sensors suffers from gain, offset, and nonlinearity errors. The sources of errors include various nonideal circuit parameters and their drift. The output of the proposed readout circuit has a special feature that it is not a function of the circuit parameters such as: 1) offset voltages of the opamps and comparators; 2) bias currents of the opamps and comparators; 3) gain of various units employed; 4) ON-resistance of the switches; 5) value or mismatch in the magnitudes of the reference voltages employed; 6) delay of the switches and comparator; 7) leakage current of the switch; and 8) slew rate of the opamp. Such a scheme will be useful for high accuracy measurements, even when the parameters 1)-8) may vary or drift, due to variation in the measurement environment. A prototype of the proposed readout scheme has been developed in the laboratory and the performance has been evaluated under various conditions. The output was found to be linear with a worst-case nonlinearity of 0.05%. Test results from a prototype developed show that the proposed scheme possesses all the features, described above, as expected. © 2017 IEEE.

IEEE Transactions on Instrumentation and Measurement

A resistive sensor readout circuit with intrinsic insensitivity to circuit parameters and its evaluation

In this paper, a novel Capacitance-to-Frequency Converter (CFC) with high linearity is presented. In the CFC, the capacitance to frequency conversion is obtained using a negative feedback mechanism. In this feedback, the frequency of the output controls the current delivered by a Switched-Capacitor (SC) network such that the difference error is automatically minimized. The proposed converter uses a dc reference voltage for the excitation and achieves high accuracy. The feedback mechanism ensures that the final output is insensitive to the linearity errors of the units employed to realize the forward path; namely a capacitance-to-voltage converter and a voltage-to-frequency converter. A prototype of the proposed CFC has been developed. The prototype was tested for sensor capacitance Cx varied from 5 pF to 25 pF. A prototype of the conventional CFC that operates in an open-loop mechanism was also developed and the linearity error was evaluated. It has been noted that the proposed closed-loop approach, reduces the worst-case nonlinearity error from 0.8% to 0.1%. This improvement is achieved without the use of any error compensating circuitries, and hence complexity level of the system remains same as a typical CFC. The prototype CFC has an update rate of 10 kS/s. The results obtained from the CFC confirmed its usefulness. © 2017 IEEE.