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To improve the model-based inversion performance of microwave induced thermoacoustic tomography for breast tumor imaging, an active adjoint modeling (AAM) method is proposed. It aims to provide a more realistic breast acoustic model used for tumor inversion as the background by actively measuring and reconstructing the structural heterogeneity of human breast environment. It utilizes the reciprocity of acoustic sensors, and adapts the adjoint tomography method from seismic exploration. With the reconstructed acoustic model of breast environment, the performance of model-based inversion method such as time reversal mirror is improved significantly both in contrast and accuracy. To prove the advantage of AAM, a checkerboard pattern model and anatomical realistic breast models have been used in full wave numerical simulations.
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http://dx.doi.org/10.1109/TBME.2014.2309912 | DOI Listing |
J Biomech
October 2025
Department of Applied Mechanics, Budapest University of Technology and Economics, Muegyetem rkp. 3., Budapest, H-1111, Hungary; HUN-REN-BME Dynamics of Machines Research Group, Muegyetem rkp.3., Budapest, H-1111, Hungary. Electronic address:
Postural balance is crucial for human daily activities, and understanding the neural-motor control mechanisms underlying balance performance is essential for improving diagnosis and intervention strategies for balance disorders. This study focuses on the human standing balance task on a harmonically moving platform with anterior-posterior translation, exploring the neural-motor control logic using a switched control strategy. It is hypothesized that humans switch between optimal energy gains and optimal decay gains to maintain balance in a safe and energy-efficient manner with the usage of optimal decay gains being closely related to balancing ability.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
August 2025
Japan Agency for Marine-Earth Science and Technology, Yokohama 236-0001, Japan.
The Nankai Trough is a major subduction zone in southern Japan capable of generating the next M7 or larger earthquake off Kii Peninsula. In addition to earthquakes characterized by sharp P and S arrivals, there are numerous slow earthquakes without clear P phases at the subducting plate boundary corresponding to transient slips that are related to fluids at the plate boundary and high pore pressure. In this study, we perform ambient noise differential adjoint tomography to derive the S-wave velocity model beneath a linear Ocean Bottom Seismometer (OBS) array, which was previously difficult based on airgun active source study.
View Article and Find Full Text PDFOn New Year's Day, January 1, 2024, a significant earthquake struck the Noto Peninsula, Japan, triggering a tsunami with a maximum height of exceeding 5 m along the coast. This rare and destructive event is associated with several active submarine faults in the area, which are inferred to have ruptured simultaneously. However, due to the lack of direct observation from the ocean, the precise nature of the initial disturbance remains uncertain.
View Article and Find Full Text PDFSoft Matter
May 2025
Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Rd, Cambridge CB3 0WA, UK.
The propulsion of many eukaryotic cells is generated by flagella, flexible slender filaments that are actively oscillating in space and time. The dynamics of these biological appendages have inspired the design of many types of artificial microswimmers. The magnitude of the filament's viscous propulsion depends on the time-varying shape of the filament, and that shape depends in turn on the spatial distribution of the bending rigidity of the filament.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
February 2025
School of Engineering and Applied Physics, Harvard University, Cambridge, MA 02138.
Inverse design of complex flows is notoriously challenging because of the high cost of high dimensional optimization. Usually, optimization problems are either restricted to few control parameters, or adjoint-based approaches are used to convert the optimization problem into a boundary value problem. Here, we show that the recent advances in automatic differentiation (AD) provide a generic platform for solving inverse problems in complex fluids.
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