Current PhD projects

Saeed Afshar

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Saeed's research focuses on the development of novel spiking (time based) neural network architectures for sensory and learning systems by incorporating insights from the fields of neuroscience, machine learning and signal processing with particular applications in Lidar and event based vision sensors. The ultimate aim of this project is to develop a suite of alternative computer processor designs and algorithms that are faster, more power efficient and better able to adapt in noisy unpredictable environments in comparison to standard computers.

The standard processors which power our laptops and PCs are marvels of human ingenuity. They are the engines of our information age and represent more than half a century of accumulated research and development. However based on the 1945 design by John von Neumann all such processors share the following properties: They are deterministic, they operate on digital representations of instructions and numbers and they do so in a sequential manner. These properties can create informational bottlenecks that are unsuitable for applications where large amounts of temporal data must be processed in real time, under noisy conditions using minimal power. The growing demand for adaptive, automated, portable systems means that number of such applications is increasing rapidly.

In contrast to standard processors the bio-inspired spiking processor designs which are the focus of this research mimic the way the brain processes information in that they are stochastic, adaptive, distributed and use time itself as the central processing element. With the help of customizable digital hardware platforms called Field Programmable Gate Arrays these alternative processor architectures and algorithms can be rapidly prototyped, tested and compared in performance, power efficiency and speed to traditional solutions against which they must compete. In this way this research aims to probe the large search space of potential solutions to real-time temporal data processing applications.

Alba Bellot Saez

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Synchronous activities within neuronal networks give rise to neural oscillations, which are thought to be involved in physiological processes. My project focuses on investigating the role of cortical astrocytes in modulating neuronal intrinsic properties, specifically in mediating the transition between different network oscillatory frequencies by manipulating the levels of extracellular K+ through K+ clearance mechanisms.

Titus Jayarathna

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Obstructive Sleep Apnoea (OSA) is a condition that affects around 9 of the world's adult population, according to research from the Australian Sleep Health Foundation, and poses serious health concerns with sufferers being more prone to depression, obesity and cardiovascular disease. The goal of Titus' project is to develop a personalised treatment that is efficient, effective and much more comfortable to use. The current treatment and monitoring devices are expensive, uncomfortable, so patients do not adhere to the therapy. This will ensure better compliance and better treatment overall.

His research is funded by a grant awarded under the federal government's Cooperative Research Centres - Projects (CRC-P) program. The project is being completed in collaboration with Oventus Medical, Medical Monitoring Solutions, CSIRO, Western Sydney University and Neuroscience Research Australia.

David Karpul

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David's project on sub-sensory electrical noise stimulation (SENS) of the peripheral nerve aims to:

  • investigate the use of SENS to alleviate peripheral neuropathic desensitisation in patients with peripheral neuropathy associated with HIV-infection;
  • investigate the effect of SENS on the pain felt by patients with peripheral neuropathic pain;
  • develop a fuller understanding of how sub-sensory electrical noise stimulation interacts with the nervous system, and investigate a means of maximally enhancing sensory function of patients with HIV related peripheral neuropathy;
  • develop and test a practical "every-day" treatment for patients with HIV related peripheral neuropathy that uses the information gained in the above points.

Peripheral neuropathy is a common problem associated with aging, diabetes, alcoholism and HIV/AIDS. Patients frequently suffer peripheral neuropathic desensitisation. These symptoms may reduce quality of life and increase the risk of secondary ailments. Restoring the functionality lost due to peripheral neuropathy would greatly improve quality of life and prognosis. Currently there is no treatment available.

Hossein Moinzadeh

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Electrocardiography (ECG) is the most popular non-invasive diagnostic tool for cardiac assessment. Vectorcardiogram (VCG) also has been repeatedly found useful for clinical investigations. Hossein is interested in using machine learning and data mining techniques to investigate ECG and VCG to have better representation of heart activity for diagnosis of cardiovascular diseases. His project involves developing methods for taking advantage of both VCG and ECG characteristics by transforming ECG to VCG. He is also involved in a project to develop a new framework to record ECG using a recently developed device which can record the voltage of right arm, left arm and left leg besides the 12 lead ECG.

Elham Shabanivaraki

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Millions of people all over the world are dealing with peripheral vascular diseases (PVD), which can cause morbidity or even mortality. However, early diagnosis of such diseases can help to prevent their consequences. Elham is interested in investigating biological signals for the use of noninvasive diagnosis, and her project focuses on developing a peripheral monitoring device, called HeMo, which can enable early diagnosis of PVDs. This device has a fabric-elasticated cuff incorporating two electro-resistive band sensors, which enable to measure the changes in blood volume due to both postural changes and arterial inflow. Preliminary results derived from Elham's project shows that this device has the potential to be used for diagnosis of peripheral arterial disease and chronic venous insufficiency. At the moment, Elham is working to develop a user-friendly version of the HeMo device and validate its performance for clinical use. As the sphygmomanometer changed the diagnosis and treatment of hypertensive disease by providing a simple means of measuring blood pressure, it is hoped that this research will do the same for peripheral vascular diseases.

Ram Singh

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Ram is exploring using computational auditory models to process multiple music instrument recordings mixed on single tracks titled polyphonic music signal. He plans to design and implement a cochlea-cortical model on digital hardware and intends to use neural networks to investigate its responses using pitch and timbre cues to extract music notes and instruments information respectively. He is also interested in the brain's predictive nature by which it manages its expectation through inference and plans to investigate such effects on note prediction using pitch information.

James Wright

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James' research focuses on interfaces with the somatosensory system, and attempts to bridge the gap between the biological nervous system and the electronic device. Many challenges exist at the neural interface, but the potential benefits of successfully negotiating these will be techniques that can be used in the restoration of sensation to stroke patients, improved assistive technologies for the elderly and disabled and new methods for the teleoperation of remote devices. Concentrating on the peripheral nervous system, we are seeking to extract a control signal from the efferent pathway suitable for directing an assistive device or prosthetic, and to return feedback from the device via the afferent pathway. This research includes materials engineering of electrodes and interfaces, signal processing to decode and encode sensory and control information, neurobiology and anatomy of the peripheral nervous system,  and computer science and electrical engineering for the construction of the device.

Ying Xu 

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Ying's project encompasses developing a neuromorphic integrated circuit (IC) and system to perform real-time auditory signal recognition and localization tasks simultaneously. This system will model the auditory periphery and mimic the neurobiological architecture present in the human nervous system. In this system, an auditory model will be built to convert input sound into frequency time auditory spectrogram. Furthermore, electronic neural systems for classifying auditory spectrograms and localizing the sound source will also be implemented.

Completed Projects:

Ram Singh (2012)

Ram's MEng project was to develop a real time simulator of cochlear filtering and auditory nerve activity.

Runchun Wang (2013)

Runchun's research project was to build neuromorphic VLSI circuits for spatio-temporal pattern recognition with spiking neurons and adaptive spike propagation delays, based on the concept of "polychronous" networks. He has designed an integrate and fire neuron, an axonal propagation delay circuit, a current synapse and associated circuits using analog VLSI.

Gregory Cohen (2016)

One of the fundamental tasks underlying much of computer vision is the detection, tracking and recognition of visual features. It is an inherently difficult and challenging problem, and despite the advances in computational power, pixel resolution, and frame rates, even the state-of-the-art methods fall far short of the robustness, reliability and energy consumption of biological vision systems.

Silicon retinas, such as the Dynamic Vision Sensor (DVS) and Asynchronous Time-based Imaging Sensor (ATIS), attempt to replicate some of the benefits of biological retinas and provide a vastly different paradigm in which to sense and process the visual world. Tasks such as tracking and object recognition still require the identification and matching of local visual features, but the detection, extraction and recognition of features requires a fundamentally different approach, and the methods that are commonly applied to conventional imaging are not directly applicable.

This thesis explores methods to detect features in the spatio-temporal information from event-based vision sensors. The nature of features in such data is explored, and methods to determine and detect features are demonstrated. A framework for detecting, tracking, recognising and classifying features is developed and validated using real-world data and event-based variations of existing computer vision datasets and benchmarks.

The results presented in this thesis demonstrate the potential and efficacy of event-based systems. This work provides an in-depth analysis of different event-based methods for object recognition and classification and introduces two feature-based methods. Two learning systems, one event-based and the other iterative, were used to explore the nature and classification ability of these methods. The results demonstrate the viability of event-based classification and the importance and role of motion in event-based feature detection.

Saeed Afshar (2016)

The motivation for project is idea that abstract, adaptive, hardware efficient, inter-neuronal transfer functions (or kernels) are the most important element in neuromorphic implementations of Spiking Neural Networks (SNN) which learn spatio-temporal patterns in hardware. In the absence of such abstract kernels, spiking neuromorphic system must realize very large numbers of synapses and their associated connectivity. The resultant hardware and bandwidth limitations create difficult tradeoffs which diminish the usefulness of such systems. In this thesis a novel model of spiking neurons is proposed. The proposed Synapto-dendritic Kernel Adapting Neuron (SKAN) uses the adaptation of their synapto-dendritic kernels in conjunction with an adaptive threshold to perform unsupervised learning and inference on spatio-temporal spike patterns. The hardware and connectivity requirements of the neuron model were minimized through the use of simple accumulator based kernels as well as through the use of timing information to perform a winner take all operation between the neurons. The learning and inference operations of SKAN are characterized and shown to be robust across a range of noise environments.

Chetan Singh Thakur (2016)

Advances in integrated circuit (IC) fabrication technology have reduced feature sizes to the order of nanometres, but have created several problems in IC design, such as lower noise immunity, increased process mismatch, and interconnect bottlenecks. Further, the failure of a few transistors may result in the failure of the entire chip, rendering it unusable. Similar to these problems of transistor failure and device mismatch in ICs, the brain is faced with the problems of heterogeneity of neuronal responses to stimuli and neuronal cell death. The biological nervous system functions well despite these problems, and this motivates us to apply its working principles in IC implementation. In this thesis, we draw inspiration from the brain and discuss how 'stochastic facilitation' can be used to perform useful and precise computation. We explore non-deterministic methodologies for computation in hardware and introduce the concept of stochastic electronics; a new way to design circuits and increase performance in noisy and mismatched fabrication environments. We illustrate this approach by presenting systems for both analogue and digital IC design.

For the analogue system, we propose a generic and trainable architecture, which uses device mismatch and nonlinearities explicitly. In this way, the reduced device matching in newer technologies becomes an advantage, rather than something that needs to be engineered out of the design. We have developed a novel neuromorphic system called a Trainable Analogue Block (TAB), which uses device mismatch as a means for random projections of the input to a higher dimensional space. The TAB framework is inspired by the principles of neural population coding operating in the biological nervous system. Three neuronal layers, namely input, hidden, and output, constitute the TAB framework, with the number of hidden layer neurons far exceeding the number of input layer neurons.

For the digital system, we use a stochastic computation (SC) framework to build massively parallel and low precision circuits to solve complex Bayesian inference problems. An advantage of the SC implementation is that it is robust to certain types of noise, which may become an issue in IC technology with feature sizes in the order of tens of nanometres due to their low noise margin, the effect of high-energy cosmicrays, and the low supply voltage. We present the implementation of two types of Bayesian inference problems to demonstrate the potential of building probabilistic algorithms in hardware. The first implementation, referred to as the BEAST (Bayesian Estimation and Stochastic Tracker), demonstrates a simple problem where an observer uses an underlying Hidden Markov Model to track a target in one dimension. In this implementation, sensors make noisy observations of the target position at discrete time steps. The tracker learns the transition model for target movement, and the observation model for the noisy sensors, and uses these to estimate the target position by solving the Bayesian recursive equation online. We show the tracking performance of the system and demonstrate how it can learn the observation model, the transition model, and the external distractor (noise) probability interfering with the observations. In the second implementation, we show how inference can be performed in a Directed Acyclic Graph (DAG) using stochastic circuits, and this implementation is referred to as the Bayesian INference in DAG (BIND). Our work describes canonical neural circuits, which are the basic building blocks of our models, and shows how these neural circuits can be easily implemented using digital logic gates. An advantage of our framework is that the flipping of random individual bits would not affect the system performance because information is encoded in a bit stream. Our work presents a novel approach for implementing probabilistic networks using simple logic gates, with the ability to perform the computation in real time.

Patrick Kasi (2017)

Patrick's research focuses on investigating the mechanisms that underlie tactile decoding. Specifically we seek to understand how information relating to area between the finger pad and object is interpreted and transformed by the brain into a format that is relevant for sensorimotor control during dexterous object manipulation. We are recording tactile afferent signals innervating the glabrous skin of the human finger pad. In addition, we are using a combination of mathematical and signal processing approaches to develop models for the analysis of the data. We hope that this will be a step towards designing robots with dexterous manipulation capabilities, inform the design of sensory feedback devices, and possibly guide the development of new methods to improve upon therapies for individuals with neurological disorders.