Department of Electrical Engineering

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 this paper, a tunable mixer having a tunable range from 868 MHz to 2.4 GHz is proposed. The structure consists of a modified tunable 3 dB double section hybrid coupler along with a tunable 3rd order low pass filter. The tunibility is achieved by varying the reverse biased voltage of the varactor diode. In the proposed circuit, only one control voltage is applied with RF choke inductors. For mixing operation, two schottky diodes are used. Working methodologies of the proposed mixer is established with extensive simulation results. Finally, proposed design gives wide tuning range, high port isolation, good return loss throughout the frequency range over 868 MHz to 2.4 GHz. © 2023 IEEE.

World University root node

2nd International Conference on Wireless, Antenna and Microwave Symposium, WAMS 2023

Novel Tunable Mixer Using Double Section Hybrid Coupler for Extended ISM Band Applications

Objective. In ultrasound (US) guided interventions, the accurate visualization and tracking of needles is a critical challenge, particularly during in-plane insertions. An inaccurate identification and localization of needles lead to severe inadvertent complications and increased procedure times. This is due to the inherent specular reflections from the needle with directivity depending on the angle of incidence of the US beam, and the needle inclination. Approach. Though several methods have been proposed for improved needle visualization, a detailed study emphasizing the physics of specular reflections resulting from the interaction of transmitted US beam with the needle remains to be explored. In this work, we discuss the properties of specular reflections from planar and spherical wave US transmissions respectively through multi-angle plane wave (PW) and synthetic transmit aperture (STA) techniques for in-plane needle insertion angles between 15 degrees-50 degrees. Main Results. The qualitative and quantitative results from simulations and experiments reveal that the spherical waves enable better visualization and characterization of needles than planar wavefronts. The needle visibility in PW transmissions is severely degraded by the receive aperture weighting during image reconstruction than STA due to greater deviation in reflection directivity. It is also observed that the spherical wave characteristics starts to alter to planar characteristics due to wave divergence at large needle insertion depths. Significance. The study highlights that synergistic transmit-receive imaging schemes addressing the physical properties of reflections from the transmit wavefronts are imperative for the precise imaging of needle interfaces and hence have strong potential in elevating the quality of outcomes from US guided interventional practices.

BIOMEDICAL PHYSICS \& ENGINEERING EXPRESS

On the physics of ultrasound transmission for in-plane needle tracking in guided interventions

In this work, we propose a model that captures the dynamic characteristics of metal-insulator-semiconductor (MIS)-based non-volatile memory (NVM). The main focus of our study is to investigate the dependence of the barrier profile (and hence, the dominant transport mechanism) on the write speed and write voltage. We evaluate the results from our model with experimental data from literature. The model and its framework can provide useful insights into the design of MIS-based NVMs with optimized performance. © 2023 IEEE.

2023 IEEE Nanotechnology Materials and Devices Conference, NMDC 2023

Modeling the Dynamic Characteristics of Metal-Insulator-Semiconductor based Non-Volatile Memories

The delay and sum (DAS) has been the popular beamforming algorithm for image reconstruction in ultrafast ultrasound imaging systems due to its low complexity implementation. However, to improve the lower contrast and resolution in images reconstructed using DAS, there have been many adaptive and non-linear beamforming algorithms developed in the recent past. One of the popular non-linear algorithms proposed in the literature, filtered delay multiply and sum (F-DMAS) is sensitive to off-axis clutters and produces artifacts that result in the degradation of the overall image quality along with a possible dynamic range alteration. In this work, a novel approach to combining the strengths of DAS and F-DMAS algorithms is proposed. The proposed approach referred to as beam multiply and sum (BMAS), employs a DAS beamformer in multiple sub-apertures at receive to form the sub-aperture beams and cross multiplies them using a multiply and sum architecture to enhance the spatial coherence and suppress the clutter artifacts. An exhaustive performance comparison in terms of dynamic range alteration, resolution, and contrast of the BMAS is performed with standard in-silico and in -vitro datasets. The results suggest that the proposed approach outperforms the DAS and F-DMAS beamformers in most cases. More than the proposal of a novel beamforming algorithm, to the best of our knowledge, the approach is the first attempt of its kind towards the possibility of the co-existence of two or more beamformers in an ultrasound imaging system. With optimal tuning, it could provide a good trade-off between the effects of improved resolution and improved contrast while keeping the dynamic range linearity unaltered.

BIOMEDICAL SIGNAL PROCESSING AND CONTROL

Beam multiply and sum: A tradeoff between delay and sum and filtered delay multiply and sum beamforming for ultrafast ultrasound imaging

Underwater acoustic imaging has been gaining popularity due to its ability to image in very turbid oceanic conditions. However, the complexity of conducting underwater experiments using expensive hardware is an infeasible solution and hence there is an importance of realistic simulation models to understand various underwater scenarios. The k-Wave toolbox models realistic underwater scenario for accurate object detection, image enhancement and classification. The advantage of k-Wave is that it offers precise and computationally effective simulation for acoustic imaging and has the advantage of modeling the 2D environment with the ability to assign the sound speed and medium density at pixel level, providing more accurate backscattered echoes for various sonar signal processing applications. However, modeling underwater scenarios requires large computational grids, resulting in huge storage memory and computation requirements resulting in limited usage of k-Wave for underwater scenarios. In this study, we propose an efficient multilayering technique for modelling underwater targets for acoustical 2D imaging using the k- Wave toolbox. It is observed that the time and memory taken was reduced by 21\% and 77.02\% when employing the proposed multi-layering technique when compared to the typical k- Wave simulations.

Underwater Target Modelling using k-Wave Toolbox by Multilayering Technique for Acoustical Imaging

Real-time 3D acoustic imaging underwater is becoming increasingly important, as 3D geometry information of underwater objects is required for autonomous underwater vehicles to avoid obstacles. A major problem for real-time imaging is the time required to process the data associated with large planar arrays and the hardware cost of uniform 2D receiving arrays. The solutions to the problem are to reduce the number of elements in the receiving array and find fast beamforming techniques for 3D imaging. In this work, we propose an efficient cross-array beamforming using spatial cross correlation of azimuth and elevation beams for underwater real-time 3D imaging. The simulation result demonstrated that the proposed method could reconstruct a 3d image of an underwater target with an inferior but acceptable resolution. The proposed method is twenty-two times faster than the conventional delay and sum beamforming for 120 x 120 beams.

An Efficient Cross Array Beamforming for Underwater Acoustical 3D imaging

We propose a novel method that leverages the combination of Blender and K-Wave software to generate a realistic acoustic dataset for side-scan sonar images. Side scan sonar (SSS) images have numerous applications in the underwater environment. However, the challenges and high cost of acquiring SSS images in real experiments and the lack of benchmark open-source datasets encourage the researchers to consider the generation of simulated SSS image datasets. There have been several attempts in the literature to combine open-source computer graphics design software such as Blender with generative adversarial networks (GANs) to generate synthetic SSS images. However, the speckles generated in all such approaches have been unrealistic; hence, the DL approaches trained for object detection employing such data are bound to fail. In the proposed method, we first generate acoustic images from Blender. Then, the CycleGAN is applied for style transfer to generate realistic acoustic images based on the speckle generated using k-Wave. The K-wave, Blender, and cycleGAN are used to generate a closed set of SSS images. We then leverage ConSinGAN to generate varying resolution high-quality sonar images from a closed set of SSS images. As per our knowledge, this is the first attempt that uses k-wave in conjunction with Blender and CycleGAN to generate SSS images. The proposed method is cost-effective and efficient alternative for acquiring large SSS datasets.

Physics driven deep learning based simulation of side scan sonar images

The high penetration of inverter-based resources (IBRs) will substantially change the dynamic behavior of the power system including inertia distribution. Real-time inertia distribution monitoring is important to support power system operation in future low inertia grids. This article presents the development and validation of a center of power-based inertia distribution estimation technique utilizing the measurements available from the phasor measurement units of the wide-area measurement systems. The suggested technique is validated on the 246-bus northern regional power grid of Indian power system. The impact of different penetration levels of IBRs on the proposed inertia distribution index (IDI) is also studied. The suggested index works purely on power system measurements and does not need any model information. Further, the impact of change in IDI on oscillation baselining study is explored. © 2007-2012 IEEE.

IEEE Systems Journal

A Practical Approach to Inertia Distribution Monitoring and Impact of Inertia Distribution on Oscillation Baselining Study for Renewable Penetrated Power Grid

A Frequency Selective Surface (FSS) based wideband reflective linear-cross and linear-circular polarization converter is proposed. The FSS consists of an H-shaped electric dipole loaded with capacitive patches printed on top of the low-loss dielectric spacer with the other side grounded. For the y/x linearly polarized wave incidence on the proposed design, the reflected wave is orthogonally polarized with a 90% Polarization Conversion Ratio (PCR) from 6.74-13.20 GHz, 15.96-17.20 GHz and 23.78-26.44 GHz. It is not only limited to that but also performs linear-circular conversion with 3-dB minimum Axial Ratio (AR) from 3.36-5.18 GHz, 17.80-21.80 GHz and 27.29-28.66 GHz. This design is highly miniaturized with a very compact structural periodicity of 0.034λL×0.040 λL and a low-profile thickness of 0.018λL, where λL is the free-space wavelength of the lowest operating frequency. Considerable stable performance is achieved for different oblique incidences. The simulated surface current patterns are investigated for top FSS and ground for multiple resonant frequencies. The dual-polarized linear-cross and linear-circular polarizing reflectors in a single design with distinct frequency bands would be ideal for dual operation based real-time applications. © 2023 IEEE.

Ultra Miniaturised Wideband Linear-to-Circular and Linear-to-Cross Polarization Conversion Reflector with H-Dipole Loaded with Capacitive Patches

In recent years, memristive neuromorphic systems have gained much attention. In this work, we developed a physics-based framework to model transport in valence change memory (VCM) memristors, implemented in Verilog-A. This has enabled us to scale up and simulate the performance of these devices in a crossbar array/neural network for pattern classification, for instance. The system's performance is analyzed based on classification accuracy in different conditions. We anticipate that this will provide useful insights into the design of these systems by analyzing their performance, based on our model. © 2023 IEEE.