The inverse filter is a technique used to adaptively focus waves through heterogeneous media. It is based on the inversion of the Green's functions matrix between the M transducers of a focusing array and N control points in the focal area. The inverse filter minimizes the pressure deposited around the focal point. However it is highly invasive, requiring the presence of N transducers or hydrophones in the focal area at the control points' locations to measure the Green's functions. This paper presents a way of reaching the inverse filter's focusing quality with a minimally invasive setup: only one transducer (at the desired focal location) is needed. This minimally invasive inverse filter takes advantage of the fact all the information about the propagation medium can be retrieved from the signals backscattered by the medium towards the focusing array, if the propagation medium is lossless. A numerical simulation is performed to test this minimally invasive inverse filter through a scattering, lossless medium. The focusing quality equals the conventional, highly invasive inverse filter's. The average spatial and temporal contrast is increased by up to 10 dB compared to the time reversal focusing.
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http://dx.doi.org/10.1121/1.2783128 | DOI Listing |
Rev Sci Instrum
January 2025
Birck Nanotechnology Center and the School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
High heat fluxes in electronic devices must be effectively dissipated to prevent local hotspots, which are critical for long-term device reliability. In particular, advanced semiconductor packaging trends toward thin form factor products increase the need for understanding and improving in-plane conduction heat spreading in anisotropic materials. The 2D laser-based Ångstrom method, an extension of traditional Ångstrom and lock-in thermography techniques, measures in-plane thermal properties of anisotropic sheet-like materials.
View Article and Find Full Text PDFFront Mol Biosci
January 2025
Department of Clinical Laboratory, The First People's Hospital of Lianyungang, The Affiliated Lianyungang Hospital of Xuzhou Medical University, The First Affiliated Hospital of Kangda College of Nanjing Medical University, Lianyungang, Jiangsu, China.
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Curr Rheumatol Rev
January 2025
Division of Trauma and Orthopaedics, Department of Surgery, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
Background: Modern sedentary lifestyles are prevalent among individuals with osteoarthritis. However, direct evidence linking such behaviours as causative factors of osteoarthritis remain limited due to the presence of confounding variables.
Objective: This study aims to determine the extent to which lifestyle factors have causal effects on osteoarthritis through a two-sample Mendelian randomisation (MR) study.
Sensors (Basel)
January 2025
Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer Sheva blvd 1, Beer-Sheva 84105, Israel.
Algorithms for detecting point targets in hyperspectral imaging commonly employ the spectral inverse covariance matrix to whiten inherent image noise. Since data cubes often lack stationarity, segmentation appears to be an attractive preprocessing operation. Surprisingly, the literature reports both successful and unsuccessful segmentation cases, with no clear explanations for these divergent outcomes.
View Article and Find Full Text PDFComput Biol Chem
December 2024
School of Computing and Information Technology, REVA University, Bengaluru, India.
Autism spectrum disorder (ASD) is the neuro-developmental disorder caused by various changes in the brain. It affects the life conditions with social interaction and communication. Most of the previous researches used the various techniques for the early detection to reduce the ASD, but it had been occurred several complications such as, time expenses, and low accessibility for diagnosis.
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