Undulatory topographical waves for flow-induced foulant sweeping

Diverse bioinspired antifouling strategies have demonstrated effective fouling-resistant properties with good biocompatibility, sustainability, and long-term activity. However, previous studies on bioinspired antifouling materials have mainly focused on material aspects or static architectures of nature without serious consideration of kinetic topographies or dynamic motion. Here, we propose a magnetically responsive multilayered composite that can generate coordinated, undulatory topographical waves with controlled length and time scales as a new class of dynamic antifouling materials. The undulatory surface waves of the dynamic composite induce local and global vortices near the material surface and thereby sweep away foulants from the surface, fundamentally inhibiting their initial attachment. As a result, the dynamic composite material with undulating topographical waves provides an effective means for efficient suppression of biofilm formation without surface modification with chemical moieties or nanoscale architectures

High-throughput Near-Memory Processing on CNNs with 3D HBM-like Memory

This article discusses the high-performance near-memory neural network (NN) accelerator architecture utilizing the logic die in three-dimensional (3D) High Bandwidth Memory- (HBM) like memory. As most of the previously reported 3D memory-based near-memory NN accelerator designs used the Hybrid Memory Cube (HMC) memory, we first focus on identifying the key differences between HBM and HMC in terms of near-memory NN accelerator design. One of the major differences between the two 3D memories is that HBM has the centralized through-silicon-via (TSV) channels while HMC has distributed TSV channels for separate vaults. Based on the observation, we introduce the Round-Robin Data Fetching and Groupwise Broadcast schemes to exploit the centralized TSV channels for improvement of the data feeding rate for the processing elements. Using synthesized designs in a 28-nm CMOS technology, performance and energy consumption of the proposed architectures with various dataflow models are evaluated. Experimental results show that the proposed schemes reduce the runtime by 16.4-39.3% on average and the energy consumption by 2.1-5.1% on average compared to conventional data fetching schemes.11Nsciescopu

Flapping dynamics of an inverted flag in a uniform flow

International audienceThe flapping motions of an inverted flag in a uniform flow were simulated using the immersed boundary method. The strain energy of the inverted flag was used as an indicator of the energy harvesting system efficiency. The flapping dynamics of and vortical structures around the inverted flag were examined in terms of the bending rigidity and the Reynolds number. Three flapping motion modes were observed: a deflected mode, a flapping mode, and a straight mode. A mode intermediate between the flapping mode and the straight mode was identified, the biased mode. The vortical structures in the wake were characterized by three modes: a vortex pair; a vortex pair with a single vortex, and two vortex pairs, during half of the flapping period. The maximum mean strain energy was obtained when the vortical structures behind the inverted flag formed a vortex pair during the flapping mode

Design of a Quasi-Direct Drive Actuator with Embedded Pulley for a Compact, Lightweight, and High-Bandwidth Exosuit

Although exosuits have several advantages compared to exoskeleton type of wearable robots, they have limitations, such as bulkiness and low control performance. This study addresses the design and evaluation of a compact, lightweight, and highly responsive actuator to be used for exosuits, based on the Quasi-Direct Drive (QDD) actuation. The design requirements of the actuator were set based on the actuation system used in the state-of-the-art exosuit from Harvard University (HE) so that it could be an improvement compared to HE. Several design concepts were comparatively evaluated to select the optimal design, and a design for the pulley embedded QDD (PEQDD) actuator was selected. The PEQDD was fabricated using mechanical components selected based on the design constraints or designed through mechanical analysis. Using a dynamometer, the efficiency map of the PEQDD was drawn. The control bandwidth comparison test with the motor originally used for HE showed improved bandwidth from 6.25 Hz to 20 Hz. Preliminary testing was done in walking and running conditions using an exosuit utilizing PEQDD. The test results showed that the actuator performance met all the design requirements