PhD Thesis Defence

Robert Sokolovskij

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PhD Thesis Defence

Ultra-thin MEMS tynodes for electron multiplication

Violeta Prodanovic

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Operational Amplifiers: Theory & Design

The course is addressing systematic analysis and design as well as hands-on simulation of operational amplifiers. It is shown that the topology of all operational amplifiers can be divided in nine main overall configurations. High-frequency compensation techniques are analyzed for all nine configurations. Special focus is on low-power low-voltage architectures with rail-to-rail output and/or input ranges. The design of fully differential operational amplifiers is developed. New emphasis is on low-offset chopper amplifiers, and capacitive coupled chopper amplifiers for high input-voltage current-sense applications. During hands-on simulation hours several input, output and overall designs will be covered.

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MSc SS Thesis Presentation

Estimating the room impulse response

Gabriele Zacca

The response of a sound system in a room primarily varies with the room itself, the position of the loudspeakers and the listening position. The room boundaries cause reflections of the sound that can lead to undesired effects such as echoes, resonances or reverberation. Therefore the location of these large reflecting surfaces is important information for sound field estimation in a room.

This work focuses on exploiting the inherent information present in echoes measured by microphones, to infer the location of nearby reflecting surfaces. A built-in microphone array is used that is co-located with the loudspeaker. The loudspeaker probes the room by emitting a known signal. A signal model is proposed which provides a relationship between reflector locations and measured microphone signals.

The locations of reflections are estimated by fitting a sparse set of modeled reflections with measurements. We present two novelties with respect to prior art. First, the method is end-to-end where from raw microphone measurements it outputs an estimate of the location of reflectors. Where specifically for the compact uniform circular microphone array the symmetry is exploited to create an algorithm that is of reduced computational complexity. Secondly, the model is extended to include a loudspeaker model that is aware of the inherent directivity pattern of the loudspeaker.

The performance of the proposed localization method is compared in simulation to the existing state-of-the-art localization methods. Real world measurements are also used to validate the proposed loudspeaker model.

MSc SS Thesis Presentation

Atrial Fibrillation: Estimation of the local activation time in high-resolution mapping data

Bart Kölling

A common cardiac arrhythmia is atrial fibrillation, which is becoming more widespread worldwide. Currently there is some understanding about the mechanisms behind atrial fibrillation, however more insight into the conduction of the atrial tissue is desired.

Therefore, invasive mapping studies have been performed where an array of electrodes is used to record the electrical activity on the heart’s surface during open-chest surgery. The moment in time when the tissue under an electrode depolarizes, called the local activation time can be used to reconstruct the propagation pattern of the signal that triggers the tissue to contract.

In this thesis, the application of the cross-correlation for estimation of the local activation time of the atria is investigated. Specifically, the benefits of not only cross-correlating electrode pairs that are close, but also pairs that are far away are evaluated. A framework is constructed, based on a graph, that defines these higher order neighbouring pairs of electrodes.

This is compared to the golden standard of using the steepest deflection of an electrogram, as well as to other methods using the cross-correlation. Experiments are done on simulated electrograms where the true activation times are available, as well as on natural data recorded from patients. Finally some future research is proposed to investigate for which morphologies the proposed cross-correlation based methods may be most effective.

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The quantum supremacy experiment

Dr. Rami Barends

Dr. Rami Barends @ Google (Credit: Austin Fowler)

Quantum supremacy, as originally defined by John Preskill, is "the day when well-controlled quantum systems can perform tasks surpassing what can be done in the classical world". I will discuss the challenges posed in performing a well-defined computational task on a programmable superconducting quantum processor, where the cost of doing the same task on a classical computer would be prohibitively higher.

MSc ME Thesis Presentation

Mauricio Rosencwaig

Master thesis defence

“Robust Feature Extraction Algorithm for analysis of Radar Targets using Multi-Object Tracking on Range Doppler Space”

Nagesh, Saravanan

In this thesis, we propose, a Robust data extraction algorithm capable of extracting reliable target features of multiple moving targets of different classes over all channels of a S Band Doppler Polarimetric Radar – PARSAX. The proposed algorithm is capable of generating a time series data by tracking, clusters of detections - representing extended targets using a multi target tracker modified to track on sequential frames of Range Doppler Maps .The targets considered in this study are Automobiles of different classes (4 wheel drive and above). A performance analysis of the algorithm, for data extraction possibility with respect to target density has been presented. In addition the possibility to use the extracted features for Radar Classification has been investigated.

MSc SS Thesis Presentation

Indoor localization using narrowband radios and switched antennas in indoor environment

Ye Cui

In this thesis, we explore the potential of indoor localization using Bluetooth narrowband radios. To start with, a data model according to the property of the conducted measurement data is developed. The conducted measurement data is radio channel measure- ments based on channel sounding technique. Then the data model is developed as a channel impulse response model and multipath signals are indicated by different time delays.

Delays are estimated after subspace estimation of the data covariance matrix. Smoothing techniques are employed to improve the covariance matrix estimate. To detect the rank of the subspace, two techniques are investigated, namely the MDL algorithm and the threshold method. New estimates for the thresholds are derived, valid for Hankel-structured data matrices. Experiments are conducted to investigate the performance and reliability of those two techniques, under different parameter values.

Next, we consider subspace-based super-resolution algorithm, in particular the MUSIC algorithm. The functionality of the MUSIC algorithm on narrowband radios measurements is tested and evaluated firstly by simulation experiments, which demonstrate the practicability of applying MUSIC algorithm on narrowband radios measurements. Then experiments are extended to the measurement data that conducted from real indoor environments, for the purpose of indoor localization realization using narrowband radios.

MS3 seminar

Ultra Wide Band Surveillance Radar

Dr. Mark E. Davis, IEEE Fellow, IEEE Distinguished Lecturer

Ultra Wide Band Surveillance Radar is an emerging technology for detecting and characterizing targets and cultural features for military and geosciences applications. It is essential to have fine range and cross-range resolution to characterize objects near and under severe clutter. This lecture will provide an in-depth look into:

  • The early history of battlefield surveillance radar
  • UWB phased array antenna
  • UWB Synthetic aperture radar (SAR)
  • UWB ground moving target indication
  • New research in multi-node ultra wind band radar

Lecturer Biography: Dr Mark E Davis has over 50 years’ experience in Radar technology and systems development. He has held senior management positions in the Defense Advanced Research Projects Agency (DARPA), Air Force Research Laboratory, and General Electric Aerospace. At DARPA, he was the program manager on both the foliage penetration (FOPEN) radar advanced development program and the GeoSAR foliage penetration mapping radar.

His education includes a PhD in Physics from The Ohio State University, and Bachelor and Master’s Degrees in Electrical Engineering from Syracuse University. He is a Life Fellow of both the IEEE and Military Sensing Symposia, and a member of IEEE Aerospace Electronics Systems Society Board of Governors, VP Conferences, and past-Chair the Radar Systems Panel. He is the 2011 recipient of the AESS Warren D White Award for Excellence in Radar Engineering, and the 2018 IEEE Dennis J. Pickard Medal for Radar Technologies and Applications.

Master thesis Defence

STEREOID data processor: Design and Performance analysis

Prithvi Laguduvan Thyagarajan

Abstract: Stereo Thermo-Optically Enhanced Radar for Earth, Ocean, Ice, and land Dynamics (STEREOID) is one of the candidates of the ESA (European Space Agency) , Earth Explorer 10 missions. The novel constellation system will consist of the active Sentinel-1 satellites and two passive spacecrafts, which can provide flexible baseline configurations. The main objective of the mission liesin monitoring the variation of spatially diverse ice sheets, the eruptions of earthquakes, the volcano activities, and the landslides, playing therefore an extremely important role in understanding the global climate dynamics and the geophysical processes involved. The purpose of the thesis is to develop an end-to-end simulator incorporating the STEREOID bistatic configuration operating in TOPS ( Terrain Observation by Progressive Scans) mode and evaluate its performance. To achieve this goal, the key component of the simulator, the SAR (Synthetic Aperture Radar) processing kernel was first implemented. The kernel employs an imaging algorithm which assists in image formation and focusing for different bistatic geometries generated by relevant working modes of the STEREOID mission. This is further extended to bistatic TOPS acquisition mode with azimuth beamforming under dual antenna receiver configuration of STEREOID. The performance of STEREOID mission is evaluated under different bistatic geometries and the dual beamforming strategy is evaluated for parameters such as resolution, pointing errors and gain imbalances. This is evaluated to analyse and understand the importance of calibration errors introduced into the system.

MSc SS Thesis Presentation

Radio astronomy image formation using Bayesian learning techniques

Yajie Tang

Radio astronomy image formation can be treated as a linear inverse problem. However, due to physical limitations, this inverse problem is ill-posed. To overcome the ill-posedness, side information should be involved. Based on the sparsity assumption of the sky image, we consider L1-regularization. We formulate the image formation problem as a L1-regularized weighted least square (WLS) problem and associate each variable with one regularization parameter. We use Bayesian learning to learn the regularization parameters from data by maximizing the posterior density. With the iterative update of the regularization parameters, the solution is updated until convergence of the regularization parameters. We involve a stopping rule based on the noise level to improve the computational eachciency and control the sparsity of the solution. We compare the performance of this Bayesian learning method with other existing imaging methods by simulations. Finally, we propose some future research directions in improving the performance of this Bayesian learning method.

MSc ME Thesis Presentation

Design and Fabrication of Dielectric Elastomer Actuators for Organ-on-Chip Platforms

Chuqian Zhang

MSc ME Thesis Presentation

MEMS ultrasound for active implantable devices

Marta Saccher

MSc ME Thesis Presentation

A Complete Overview on Realizing Transfer-free Graphene-based Differential Pressure Sensor

Raghutham Ramesha

MSc SS Thesis Presentation

A Generative Neural Network Model for Speech Enhancement

Husain Kapadia

Listening in noise is a challenging problem that affects the hearing capability of not only normal hearing but especially hearing impaired people. Since the last four decades, enhancing the quality and intelligibility of noise corrupted speech by reducing the effect of noise has been addressed using statistical signal processing techniques as well as neural networks. However, the fundamental idea behind implementing these methods is the same, i.e., to achieve the best possible estimate of a single target speech waveform. This thesis explores a different route using generative modeling with deep neural networks where speech is artificially generated by conditioning the model on previously predicted samples and features extracted from noisy speech. The proposed system consists of the U-Net model for enhancing the noisy features and the WaveRNN synthesizer (originally proposed for text-to-speech synthesis) re-designed for synthesizing clean sounding speech from noisy features. Subjective results indicate that speech generated by the proposed system is preferred over listening to noisy speech, however, the improvement in intelligibility is limited. 

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MSc ME Thesis Presentation

An ASIC with Bipolar High-Voltage Transmit Switching for a Single-Cable Intra-Vascular Ultrasound Probe

Rishabh Nagarkar

An ASIC is presented for intra-vascular ultrasound imaging. Despite being connected via a single coaxial cable, it is able to pass arbitrary high-voltage bipolar signals to the transducers for acoustic imaging. The thesis talks about the need to reduce the cable count to one and reviews the existing work in literature. It builds upon an existing single-cable design and focuses on the transmit part to make it compatible with a large number of ultrasound imaging modes by allowing it to pass high-frequency signals up to 20MHz and bipolar signal voltages up to +/-25V. The chip is phantom powered and thus its power supply and signals are transmitted on the same cable. The transmit switch designed for this ASIC is powered by and controlled by an on-chip low-voltage supply and circuitry. The prototype ASIC has been designed in TSMC 180nm HV BCD Gen2 technology. This single-cable design has 16 elements for transmit and 64 elements in the receive mode and has been evaluated using simulations.