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This work explores integrating sparse recovery methods into the ray space transform. Sparse recovery methods have proven useful in microphone array analysis of sound fields. In particular, they can provide extremely accurate estimates of source direction in the presences of multiple, simultaneous sources and noise. The ray space transform has recently emerged as a useful tool to analyse sound fields,...
This study aims to investigate the apparent backscatter of cancellous bone from the second ultrasonic harmonics using an imaging system. A cylinder model was used as the bone trabecular model and a positive correlation was found between the power spectrum of the second harmonics and trabecular thickness. The result of the in vitro experiment using ultrasound imaging system shows that the apparent...
Random projections have recently emerged as a powerful technique for large scale dimensionality reduction in machine learning applications. Crucially, the projection can be obtained from sparse probability distributions, enabling hardware implementations with little overhead. In this paper, we describe a Field-Programmable Gate Array (FPGA) implementation alongside a kernel adaptive filter (KAF) that...
Neuromorphic engineering is a discipline of electrical engineering that aims to develop signal processing systems using biological neural systems as inspiration. As such it has the dual goal of building models of neural systems in order to better understand them, and of building systems to perform useful functions for particular applications. While neuromorphic engineers extensively develop and use...
Electrical Impedance Tomography can detect changes within human body like tumours, ventilation or cardiac abnormalities using electrodes on the surface. However, EIT images are poor when the changes occur far from the electrodes, in the deep, innermost tissue. A possible method to improve measurements is to position one or more internal electrodes near the expected location of the impedance change...
Recent studies have shown high correlation between pulmonary perfusion mapping with impedance contrast enhanced Electrical Impedance Tomography (EIT) and standard perfusion imaging methods such as Computed Tomography (CT) and Single Photon Emission Computerized Tomography (SPECT). EIT has many advantages over standard imaging methods as it is highly portable and non-invasive. Contrast enhanced EIT...
Super-resolution acoustic imaging is a powerful technique for sound field analysis in which a mixture of acoustic signals is decomposed into a sparse set of components selected from a dictionary of spatial directions. In previous work, we have shown that sparse recovery with a reasonably uniform spatial dictionary can be used to increase the resolution of the image of the sound field recorded by a...
In this paper, we present a novel beamforming algorithm that is designed for spherical microphone arrays and formulated in the spherical harmonic domain. The proposed algorithm employs sparse recovery, a compressed sensing technique, and assumes the position of the source signals are unknown. A formal listening test was conducted to evaluate the performance of the proposed algorithm and the results...
This paper proposes an improved structural similarity method for audio quality assessment, which is Structural Similarity Analysis of Modulation (SSAM). Different from original structural similarity index measure, we introduce the analysis of structural similarity of modulation together with Computational Auditory Signal-processing and Perception (CASP) model. Audio features from CASP are extended...
Manual measurements of small changes in retinal vascular diameter are slow and may be subject to considerable observer-related biases. Among the conventional automatic methods the sliding linear regression filter (SLRF) demonstrates the least scattered and most repeatable coefficients. For optimal performance it relies on the choice of the correct filter scale for different vessel sizes. A small scale...
In this paper, we present a novel multichannel dereverberation algorithm that enhances a target signal in a reverberant environment. The proposed algorithm is designed for a spherical microphone array and formulated in the spherical harmonic domain. The algorithm employs sparse recovery, a compressed sensing technique, to estimate the position of the target signal and its early reflections. Room impulse...
This paper describes the design of an auto-associative memory based on a spiking neural network (SNN). The architecture is able to effectively utilize the massive interconnect resources available in FPGA architectures as a good match to the axons in biological neural networks. A complete implementation of the memory on a single FPGA is presented. The signal processing circuitry is composed from simple,...
This paper considers the application of compressed sensing to spherical acoustics in order to improve spatial sound field reconstruction. More specifically, we apply compressed sensing techniques to a set of Ambisonic sound signals to obtain a super-resolution plane-wave decomposition of the original sound field. That is to say, we investigate using the plane-wave decomposition to increase the spherical...
A novel technique for time domain spatial sound reproduction using compressed sensing is presented. The presented technique is based on the application of compressed sensing theory, which is used to improve the accuracy of the reconstructed sound field. In addition, singular value decomposition is also applied, which acts to significantly reduce the size of the data set to process, thus making it...
We present an implementation of a programmable axonal propagation delay circuit which uses one first-order log-domain low-pass filter. Delays may be programmed in the 5–50ms range. It is designed to be a building block for time-delay spiking neural networks. It consists of a leaky-integrate-and-fire core, a spike generator circuit, and a delay adaptation circuit.
This paper analyses a filter known as the Tau Cell using symbolic methods and shows that the operation of this filter is independent of the magnitude of the input DC offset. This means that the circuit places no restrictions on whether the input DC offset is a sub-threshold current or not. The circuit behaviour predicted from symbolic analysis was observed in similar circuits on a chip fabricated...
We present a new, low power EEG recording system with an ultra-high input impedance that enables the use of long-lasting, passive dry electrodes. It incorporates Bluetooth wireless connectivity and is designed to be suitable for long-term monitoring during daily activities.The new EEG system is compared to a standard and clinically available reference EEG system using wet electrodes in three separate...
Electrical Impedance Tomography (EIT) calculates the internal conductivity distribution within a body using electrical contact measurements. Conventional EIT reconstruction methods solve a linear model by minimizing the least squares error, i.e., the Euclidian or L2-norm, with regularization. Compressed sensing provides unique advantages in Magnetic Resonance Imaging (MRI) when the images are transformed...
Phonotaxis is the ability to orient towards or away from sound sources. Crickets can locate conspecifics by phonotaxis to the calling (mating) song they produce, and can evade bats by negative phonotaxis from echolocation calls. The behaviour and underlying physiology have been studied in some depth, and the auditory system solves this complex problem in a unique manner.Experiments conducted on a...
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