P S

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Sampling Schemes for Multidimensional Nonbandlimited Signals

I declare that the content embodied in this thesis is the outcome of my own

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Music Source Separation Based on a Lightweight Deep Learning Framework (DTTNET: DUAL-PATH TFC-TDF UNET)

arXiv (Cornell University), Sep 14, 2023

Music source separation (MSS) aims to extract 'vocals', 'drums', 'bass' and 'other' tracks from a... more Music source separation (MSS) aims to extract 'vocals', 'drums', 'bass' and 'other' tracks from a piece of mixed music. While deep learning methods have shown impressive results, there is a trend toward larger models. In our paper, we introduce a novel and lightweight architecture called DTTNet 1 , which is based on Dual-Path Module and Time-Frequency Convolutions Time-Distributed Fully-connected UNet (TFC-TDF UNet). DTTNet achieves 10.12 dB cSDR on 'vocals' compared to 10.01 dB reported for Bandsplit RNN (BSRNN) but with 86.7% fewer parameters. We also assess pattern-specific performance and model generalization for intricate audio patterns.

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Block-3 Measurement and Sampling

IGNOU eBooks, 2018

How Well Do Self-Supervised Models Transfer to Medical Imaging?

Journal of Imaging, Dec 1, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more

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Quasi-elliptic ultra-wideband bandpass filter with super-wide stopband

AEU - International Journal of Electronics and Communications, 2019

This paper describes a low-loss and compact planar ultra-wideband (UWB) quasi-elliptical bandpass... more This paper describes a low-loss and compact planar ultra-wideband (UWB) quasi-elliptical bandpass filter, which is based on a via-free multimode resonator (MMR) that requires no defected ground plane. The MMR structure essentially consists of a step impedance transmission-line resonator that is loaded centrally with a folded open-circuited stub. The MMR structure is also loaded with two pairs of short high impedance stubs with their ends folded towards the central stub. The proposed MMR structure excites several resonant modes comprising three even and two oddmodes within the filter's passband. The resulting transmission response is highly selective with a low-loss (0.4 dB) passband across 3.60 GHz-11.3 GHz when fabricated on a conventional dielectric substrate, which is otherwise only possible using high temperature superconductors. In addition, the structure generates transmission zeros to yield a filter that exhibits an extremely wide stopband extending up to 35.5 GHz for S21 ≥ 20 dB. The via-free planar filter structure makes its design and construction easy and economical for mass production. The filter's performance was verified through measurements. The planar filter structure can be easily manufactured using standard PCB technology.

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Multidimensional Nonbandlimited Signals

I declare that the content embodied in this thesis is the outcome of my own research work under t... more I declare that the content embodied in this thesis is the outcome of my own research work under the guidance of my thesis advisor Dr P. L. Dragotti. Any ideas or quotations from the work of other people, published or otherwise, are fully acknowledged in accordance with the standard referencing practices of the discipline. The material of this thesis has not been submitted for any degree at any other academic or professional institution.

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Audio Barlow Twins: Self-Supervised Audio Representation Learning

ICASSP 2023 - 2023 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

The Barlow Twins self-supervised learning objective requires neither negative samples or asymmetr... more The Barlow Twins self-supervised learning objective requires neither negative samples or asymmetric learning updates, achieving results on a par with the current state-of-the-art within Computer Vision. As such, we present Audio Barlow Twins, a novel self-supervised audio representation learning approach, adapting Barlow Twins to the audio domain. We pre-train on the large-scale audio dataset AudioSet, and evaluate the quality of the learnt representations on 18 tasks from the HEAR 2021 Challenge, achieving results which outperform, or otherwise are on a par with, the current state-of-the-art for instance discrimination self-supervised learning approaches to audio representation learning. Code at https://github.com/jonahanton/SSL_audio.

format_quoteAudio Barlow Twins adapts the Barlow Twins method to audio, achieving competitive results with state-of-the-art self-supervised approaches.format_quote

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Interaction Between Closely Packed Array Antenna Elements Using Meta‐Surface for Applications Such as MIMO Systems and Synthetic Aperture Radars

Radio Science, 2018

The paper presents a technique to enhance the isolation between adjacent radiating elements that ... more The paper presents a technique to enhance the isolation between adjacent radiating elements that is common in densely packed antenna arrays. Such antennas provide frequency beam-scanning capability needed in multiple-input multiple-output (MIMO) systems and synthetic aperture radars. The method proposed here uses a metamaterial decoupling slab (MTM-DS), which is located between radiating elements, to suppress mutual coupling between the elements that would otherwise degrade the antenna efficiency and performance in both the transmit and receive mode. The proposed MTM-DS consists of mirror imaged E-shaped slits engraved on a microstrip patch with inductive stub. Measured results confirm over 9-11 GHz with no MTM-DS the average isolation (S 12) is À27 dB; however, with MTM-DS the average isolation improves to À38 dB. With this technique the separation between the radiating element can be reduced to 0.66λ 0 , where λ 0 is free space wavelength at 10 GHz. In addition, with this technique there is 15% improvement in operating bandwidth. At frequencies of high impedance match of 9.95 and 10.63 GHz the gain is 4.52 and 5.40 dBi, respectively. Furthermore, the technique eliminates poor front-to-back ratio encountered in other decoupling methods. MTM-DS is also relatively simple to implement. Assuming adequate space is available between adjacent radiators the MTM-DS can be fixed retrospectively on existing antenna arrays, which makes the proposed method versatile.

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Brazil Method of Anti-Malware Evaluation and Cyber Defense Impacts

Journal of Applied Security Research

Method and tool for generating table of relevance in literature review (MTTR)

Every day, researchers in computing and IT are challenged with several articles that they need to... more Every day, researchers in computing and IT are challenged with several articles that they need to rate, classify and separate quickly and effectively to contextualize and further advance their research effectively. It is considered that literature review is the most important step of discovery. Notably, a literature review is a part that allows the researcher to adjust the perspectives and limitations of an area of study. However, there is a lack of effective methods and tools for this activity. Often, traditional knowledge management techniques result in the “Gordian Knot” slowing down the process of literature review considerably. In this article, we present a Method and Tool for Generating Table of Relevance in Literature Review (MTTR). The MTTR is an innovative organizing method supported by software tools that make the literature review activity more efficient, faster and cheaper. An interesting feature of MTTR is data visualization using the Heat Map technique, Word Cloud and ...

format_quoteMTTR facilitates systematic and non-systematic reviews, integrating content from key sections for improved organization and visualization.format_quote

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Metamaterial-Inspired Antenna Array for Application in Microwave Breast Imaging Systems for Tumor Detection

IEEE Access, 2020

This paper presents a study of a planar antenna-array inspired by the metamaterial concept where ... more This paper presents a study of a planar antenna-array inspired by the metamaterial concept where the resonant elements have sub-wavelength dimensions for application in microwave medical imaging systems for detecting tumors in biological tissues. The proposed antenna consists of square-shaped concentric-rings which are connected to a central patch through a common feedline. The array structure comprises several antennas that are arranged to surround the sample breast model. One antenna at a time in the array is used in transmission-mode while others are in receive-mode. The antenna array operates over 2-12 GHz amply covering the frequency range of existing microwave imaging systems. Measured results show that compared to a standard patch antenna array the proposed array with identical dimensions exhibits an average radiation gain and efficiency improvement of 4.8 dBi and 18%, respectively. The average reflection-coefficient of the array over its operating range is better than S 11 ≤ −20 dB making it highly receptive to weak signals and minimizing the distortion encountered with the transmission of short duration pulse-trains. Moreover, the proposed antenna-array exhibits high-isolation on average of 30dB between radiators. This means that antennas in the array (i) can be closely spaced to accommodate more radiators to achieve higher-resolution imaging scans, and (ii) the imagining scans can be done over a wider frequency range to ascertain better contrast in electrical parameters between malignant tumor-tissue and the surrounding normal breast-tissue to facilitate the detection of breast-tumor. It is found that short wavelength gives better resolution. In this experimental study a standard biomedical breast model that mimics a real-human breast in terms of dielectric and optical properties was used to demonstrate the viability of the proposed antenna over a standard patch antenna in the detection and the localization of tumor. These results are encouraging for clinical trials and further refinement of the antenna-array. INDEX TERMS Array antenna, microstrip technology, metamaterial, microwave breast imaging systems, biosensor, tumor detection, cancer, medical imaging.

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Double-Port Slotted-Antenna with Multiple Miniaturized Radiators for Wideband Wireless Communication Systems and Portable Devices

Progress In Electromagnetics Research C, 2019

Proof-of-concept is presented of a novel slot antenna structure with two excitation ports. Althou... more Proof-of-concept is presented of a novel slot antenna structure with two excitation ports. Although this antenna provides a wide impedance bandwidth, its peak gain and optimum radiation efficiency are observed at its mid-band operational frequency. The antenna structure is etched on the top side of a dielectric substrate with a ground plane. The antenna essentially consists of a rectangular patch with two dielectric slots in which multiple coupled patch arms embedded with H-shaped slits are loaded. The two dielectric slots are isolated from each other with a large H-shaped slit. The radiation characteristics of the proposed antenna in terms of impedance bandwidth, gain and efficiency can be significantly improved by simply increasing the number of radiation arms and modifying their dimensions. The antenna's performance was verified by building and testing three prototype antennas. The final optimized antenna exhibits a fractional bandwidth of 171% (0.5-6.4 GHz) with a peak gain and maximum radiation efficiency of 5.3 dBi and 75% at 4.4 GHz, respectively. The antenna has physical dimensions of 27×37×1.6 mm 3 corresponding to electrical size of 0.0452λ 0 ×0.0627λ 0 ×0.0026λ 0 , where λ 0 is freespace wavelength at 0.5 GHz. The antenna is compatible for integration in handsets and other broadband wireless systems that operate over L-, Sand nd C-bands.

$Table 1. (a) Bandwidth of Antenna-1. which is necessary to minimize mutual coupling between the ports. The simulated and measured impedance and fractional bandwidths, and inter-port isolation are given in Table 1. The simulated and measured gain and efficiency responses of the antenna in Fig. 3(a) show that the antenna has a measured peak gain and efficiency of 3.2 dBi and 57%, respectively, at 4.6GHz. The bell-shaped gain bandwidth response resembling a reduced Q-factor profile results from the multiple radiating elements constituting the antenna. The measured gain and efficiency characteristics as a function of frequency are summarized in Table 2. The simulated and measured radiation patterns, shown in Fig. 3(b), reveal that the antenna radiates approximately omnidirectionally in both E-plane and H-planes. There is good correlation between the simulated and measured results.$

$Table 2. Gain and efficiency of Antenna-1. 2.2. Antenna-2 with Ten Miniature Radiation Arms The size and structure of Antenna-2 is identical to Antenna-1, shown in Fig. 1, with (i) the inclusion of four additional miniature radiation patches with H-slits; (ii) the reduction in the inter-port gap; and (iii) the reduction in the inter-port H-slit, as shown in Fig. 4. The simulated and measured reflection and transmission-coefficient responses of Antenna-2, shown in Fig. 5, reveal improvement in the antenna’s performance by introducing these changes, which is attributed to reduction in the antenna’s Q-factor. When the antenna is excited through port-1, its impedance bandwidth improves to 5.2 GHz (0.8-6 GHz) for Sy, < —10dB, with a corresponding fractional bandwidth 152.94%. When the antenna is excited through port-2, its bandwidth is 5.2 GHz (0.85-6.05 GHz), and the corresponding fractional bandwidth is 150.72%. The transmission-coefficient in Fig. 5 shows that the inter-port isolation is better than 25 dB.$

$Table 7. Characteristics of the proposed antenna compared with state-of-the-art designs. FBW represents the fractional bandwidth. Metamaterial techniques are used in [8] & [20] to improve the antenna’s performances. Left-handec metamaterial structure in [8] is realized with spiral inductors that are connected to the ground plan by metallic via-holes, and the antenna structure in [20] needs to be terminated in 50-ohm load. The proposed antenna avoids the use of spiral inductors and metallic via-holes or load termination whicl introduce additional design complexity and therefore increase fabrication cost.$

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Meta-Surface Wall Suppression of Mutual Coupling Between Microstrip Patch Antenna Arrays for THZ-Band Applications

Progress In Electromagnetics Research Letters, 2018

This paper presents a novel 2D meta-surface wall to increase the isolation between microstrip pat... more This paper presents a novel 2D meta-surface wall to increase the isolation between microstrip patch radiators in an antenna array that is operating in the teraherz (THz) band of 139-141 GHz for applications including communications, medical and security screening systems. The metasurface unit-cell comprises conjoined twin 'Y-shape' microstrip structures, which are inter-digitally interleaved together to create the meta-surface wall. The proposed meta-surface wall is free of via holes and defected ground-plane hence easing its fabrication. The meta-surface wall is inserted tightly between the radiating elements to reduce surface wave mutual coupling. For best isolation performance the wall is oriented orthogonal to the patch antennas. The antenna array exhibits a gain of 9.0 dBi with high isolation level of less than −63 dB between transmit and receive antennas in the specified THz-band. The proposed technique achieves mutual coupling suppression of more than 10 dB over a much wider frequency bandwidth (2 GHz) than achieved to date. With the proposed technique the edge-to-edge gap between the transmit and receive patch antennas can be reduced to 2.5 mm. Dimensions of the transmit and receive patch antennas are 5 × 5 mm 2 with ground-plane size of 9 × 4.25 mm 2 when being constructed on a conventional lossy substrate with thickness of 1.6 mm.

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Wideband microstrip quasi-elliptic function bandpass filter with high out-of-band rejection

Microwave and Optical Technology Letters, 2019

Presented in the paper is a novel and compact quasielliptic function bandpass filter based on mic... more Presented in the paper is a novel and compact quasielliptic function bandpass filter based on microstrip technology that exhibits a high out-of-band rejection over a very wide frequency range. The design comprises stub loaded halfwavelength resonators that are electromagnetically coupled to resonant structures that are interdigitally coupled to the input and output feed-lines. Perturbation introduced by the presence of the stub causes the resonators to act as a multimode device. In addition, the stub introduces two transmission zeros to significantly improve the filter's passband selectivity and suppress harmonic and spurious modes. This configuration yields a wideband response with low insertion-loss of 0.73 dB, high return-loss < 20 dB, and out-of-band rejection level > 40 dB across 2-4.5 GHz and 5.74-16 GHz. The planar filter structure can be easily manufactured using standard PCB technology.

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Bio-Inspired Framework for Security in IoT Devices

Intelligent Sustainable Systems, 2022

One of the many things COVID-19 has taught humanity is that the Internet is not just a commodity ... more One of the many things COVID-19 has taught humanity is that the Internet is not just a commodity but a vital service integral to the modern world. As we become ever more connected, there is a growing need to secure data and communication streams. If data is valued, then it should be protected. Unfortunately, some of the least secure devices in modern electronic systems are the Internet of Things (IoT) devices—partly due to their low processing power and always—on functionality. Polymorphism is the notion of changing one’s form. In biological organisms, polymorphic (mutating or changing) viruses trick the natural security mechanisms by changing their unique signatures (e.g. DNA or proteins). In computing, antivirus software systems are adapted to detect and remove constantly changing software viruses. However, polymorphism at the firmware level and over the wireless medium is neither well understood nor explored for IoT devices. This paper proposes a novel and bio-inspired framework ...

Shapes from Samples Using Moments and Radon Projections

In this paper, we extend the results on sampling the signals with finite rate of innovation (FRI)... more In this paper, we extend the results on sampling the signals with finite rate of innovation (FRI) [1] in higher dimensions using kernels that reproduce polynomials [2]. In particular, we show that convex-bilevel polygons, 2-D Diracs, and quadrature domains (e.g. ellipses and cardioids) can be perfectly reconstructed from their samples using complex-moments based approach [3], while more general shapes (signals) such as piecewise polynomials with polygonal boundaries, and n-dimensional Diracs and bilevel poly-topes can be reconstructed from their samples by integrating the Radon-moment connection [3] with the annihilating-filter-based-back-projection (AFBP) reconstruction [4]. 1.

Sampling Schemes for 2-D Signals with Finite Rate of Innovation Using Kernels that Reproduce Polynomials

In this paper, we propose new sampling schemes for classes of 2-D signals with finite rate of inn... more In this paper, we propose new sampling schemes for classes of 2-D signals with finite rate of innovation (FRI). In particular, we consider sets of 2-D Diracs and bilevel polygons. As opposed to using only sinc or Gaussian kernels [7], we allow the sampling kernel to be any function that reproduces polynomials.

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IoT-Based Horticulture Monitoring System

Intelligent Sustainable Systems

With climate change and global warming in mind, vertical farms, hydroponics and urban greenhouses... more With climate change and global warming in mind, vertical farms, hydroponics and urban greenhouses can now be found in many cities worldwide as we transform the ways we produce food. Additionally, recent implications of the COVID-19 pandemic prove that as a society we can harness the benefit of remote monitoring and automation for controlled-environment agriculture and horticulture. The subject matter of this paper is implementation of a solar-powered, Internet of Things (IoT)-based Real-time Autonomous Horticulture Monitoring System (RAHMS). The RAHMS integrates a mobile application for viewing the greenhouse crop data and camera feed of plants, and interacts with cloud databases such as Firebase and MATLAB ThingSpeak for the scalability. In particular, a simple and distinctive design of a solar-powered, low energy consuming, and inexpensive greenhouse monitoring system is presented. The paper outlines RAHMS design methodology and showcases a proof-of-concept prototype with its core hardware and software components. The proposed system has a potential to further advance the practical aspects of the remote solutions for the cultivation and monitoring of horticulture and controlled-environment agriculture.

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Smart, Secure and Sustainable Robotic Hand

2020 Fourth World Conference on Smart Trends in Systems, Security and Sustainability (WorldS4), 2020

The subject matter of this paper is a smart design, control and security of a consumer-grade 3D p... more The subject matter of this paper is a smart design, control and security of a consumer-grade 3D printed robotic hand that replicates the hand movements controlled by a user-glove. The hand is controlled wirelessly through a secure server-client model. It also incorporates a simple but real-time signal processing and filtering to reduce noise and anomalies. In terms of materials used for 3D printing, a conscious decision was taken to use Polylactic acid (PLA) or PLA based wood filament which is recyclable and biodegradable. This paper also outlines the framework of Computer-Aided Design (CAD) models, 3D printing, programming, encryption, and testing. Overall, this paper presents a unique design of building a robotic hand using 3D printing and commonly used microcontroller to minimise costs and to maximise bespoke designs to individual needs.

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