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原文传递 Fast Ultrasound System for Imaging and Probing the Dynamic Response of Granular Materials.

题名：	Fast Ultrasound System for Imaging and Probing the Dynamic Response of Granular Materials.
作者：	Jaeger, H.
关键词：	Granular materials, Flow fields, Ultrasounds, Shear flow, High speed cameras, Non-newtonian flows, High-speed ultrasound imaging systems
摘要：	Granular materials are random aggregates of a large number of macroscopic, individually solid particles that interact primarily via dissipative contacts among neighboring grains. They exhibit complex dynamics in which the aggregate can transition between solid-like "jammed" and liquid-like "unjammed" behavior. Connecting local, particle-scale properties to the overall, aggregate response when large stresses are applied is of fundamental interest for developing accurate models for the onset (or demise) of aggregate rigidity. It also provides a path toward engineering new classes of particulate materials with aggregate responses "by design." This project established new research capabilities high-speed, non-invasive ultrasound imaging of particle configurations during jamming and unjamming events. An advanced ultrasound imaging system was set up and calibrated for imaging of fast jamming processes in dense suspensions of non-Brownian particles,such as propagating density fronts, where both high temporal and spatial resolution is required. The ultrasound imaging system is comprised of hardware components for shaping, transmitting and receiving ultrasound signals in the frequency range 1-15MHz and can achieve acquisition rates up to 10,000 full image frames per second.
报告类型：	科技报告