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In this work we are describing a multi-modal short-range navigation system for precision positioning tasks such as docking of a robotic vehicle in 3d space. The two input modalities, a monocular camera tracking a visual marker and an array of 3-axis magnetometers tracking a magnet, were chosen to cover a wide range of environmental conditions in order to increase the versatility and robustness of...
We theoretically propose a pathway to low-loss plasmonics. We show that dielectric-on-metal nanoresonators scatter more strongly than is possible in all-metal or all-dielectric approaches, offer near-unity-efficiency spontaneous-emission enhancements, and are robust to quantum corrections.
In this paper, we investigate robust beamforming techniques for wideband signal processing in noisy and reverberant environments. In such environments, steering vector estimation errors are inevitable, leading to a degradation of the beamformer performance. Here, we study two types of beamformers that are robust against steering vector estimation errors. The first type includes robust Capon beamformers,...
Ultrasound super-resolution imaging can be achieved by localizing spatially isolated microbubble contrast agents over multiple imaging frames. In vivo images with resolutions of ∼10–20 microns in deep tissue have been demonstrated. The technique has the potential to revolutionize the way micro-circulation can be visualized and quantified, and has implications in a wide range of clinical applications...
Fundamental frequency estimation is an important task in speech and audio analysis. Harmonic model-based methods typically have superior estimation accuracy. However, such methods usually assume that the fundamental frequency and amplitudes are stationary over a short time frame. In this paper, we propose a Kalman filter-based fundamental frequency estimation algorithm using the harmonic model, where...
The benefits of emerging wide-band gap semiconductors can only be utilized if the semiconductor is properly packaged. Capacitive coupling in the package causes electromagnetic interference during high dv/dt switching. This paper investigates the current flowing in the parasitic capacitance between the output node and the grounded heat sink for a custom silicon carbide power module. A circuit model...
Super-resolution techniques that localise isolated bubble signals first require detection algorithms to separate the bubble and tissue responses. This work explores the available bubble detection techniques for super-resolution of tumour microvasculature. Pulse inversion (PI), differential imaging (DI) and singular value decomposition (SVD) filtering were compared in terms of the localisation accuracy,...
Sub-diffraction imaging, also known as ultrasound localization microscopy, is a novel method that can overcome the fundamental diffraction limit by localizing spatially isolated microbubbles. This method requires the use of a low concentration of microbubbles to ensure that they are spatially isolated. For in vivo microvascular imaging, especially for cancer tissue with high microvascular density,...
This paper investigates gate driver design challenges encountered due to the fast switching transients in medium voltage half bridge silicon carbide MOSFET power modules. The paper presents, design of a reduced isolation capacitance regulated DC-DC power supply and a gate driver with an active Miller clamp circuit for a 10 kV half bridge SiC MOSFET power module. Designed power supply and the gate...
Super-resolution ultrasound has potential for visualisation of microvasculature1. Techniques that localise isolated bubble signals first require detection algorithms to separate the bubble and tissue response. Resolution of the tortuous microvasculature requires localisations with accuracy on the micron scale. Tumour microvasculature blood velocities are <1mm/s, and even for vessel diameters approaching...
Clinical implementation of super-resolution (SR) ultrasound imaging requires accurate single microbubble detection, and would benefit greatly from automation in order to minimize time requirements and user dependence. We present a machine learning based post-processing tool for the application of SR ultrasound imaging, where we utilize superpixelation and support vector machines (SVMs) for foreground...
Medium voltage 10 kV Silicon Carbide MOSFETs, introduce challenges regarding converter design. Very high rate of voltage change and capacitive couplings to for example cooling systems cause increased electromagnetic interference. The aim of this paper is to accurately model the capacitive coupling to a heat sink and experimentally validate the model. An analytic model of the heat sink is developed...
The structure of microvasculature cannot be resolved using clinical B-mode or contrast-enhanced ultrasound (CEUS) imaging due to the fundamental diffraction limit at clinical ultrasound frequencies. It is possible to overcome this resolution limitation by localizing individual microbubbles through multiple frames and forming a super-resolved image. However, ultrasound super-resolution creates its...
Physiologically important pressures in the heart and aorta are currently assessed with invasive pressure catheters. The subharmonic signal from ultrasound contrast agents, however, may be exploited to estimate pressures non-invasively. The objective of this work was (i) to develop a static phantom from commercially-available components for easy replication across different laboratories, and (ii) to...
Physiologically important pressures in the heart and aorta are currently assessed with invasive pressure catheters. The subharmonic signal from microbubble ultrasound contrast agents, however, may be exploited to estimate pressures non-invasively. The objective of this work was (i) to develop a static phantom from commercially-available components for easy replication across different laboratories,...
Recently, acoustic super-resolution (SR) imaging has allowed visualization of microvascular structure and flow beyond the diffraction limit through the localization of many isolated microbubble signals. Each bubble position is typically estimated by calculating the centroid, finding a local maximum, or finding the peak of a 2-D Gaussian function fit. However, the backscattered signal from a microbubble...
Sub-diffraction imaging, also known as super-resolution (SR) imaging, is a novel method that can overcome the fundamental diffraction limit by localizing spatially isolated microbubbles (MBs). A low concentration of MBs is required to achieve isolated signals in microvasculature, which is especially challenging in cancerous tissue due to high vessel density and slow flow. This study proposes a frequency...
The structure of microvasculature cannot be resolved using clinical B-mode or contrast-enhanced ultrasound (CEUS) imaging due to the fundamental diffraction limit. It is possible to overcome this resolution limitation by localizing individual microbubbles (MBs) through multiple frames and forming a super-resolved image. However, super-resolution (SR) imaging bring their own unique problems since the...
Robots are becoming increasingly prevalent in our society in forms where they are assisting or interacting with humans in a variety of environments, and thus they must have the ability to sense and detect objects by touch. An ongoing challenge for soft robots has been incorporating flexible sensors that can recognize complex motions and close the loop for tactile sensing. We present sensor skins that...
The work presented in this paper describes the use and evaluation of machine learning techniques like neural networks and support vector regression to learn a model of magnetic field distortions often induced in inertial measurement units using magnetometers by changing currents, postures or configurations of a robotic system. Such a model is needed in order to compensate the local dynamic distortions,...
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