scholarly journals Unearthing real-time 3D ant tunneling mechanics

2021 ◽  
Vol 118 (36) ◽  
pp. e2102267118
Author(s):  
Robert Buarque de Macedo ◽  
Edward Andò ◽  
Shilpa Joy ◽  
Gioacchino Viggiani ◽  
Raj Kumar Pal ◽  
...  

Granular excavation is the removal of solid, discrete particles from a structure composed of these objects. Efficiently predicting the stability of an excavation during particle removal is an unsolved and highly nonlinear problem, as the movement of each grain is coupled to its neighbors. Despite this, insects such as ants have evolved to be astonishingly proficient excavators, successfully removing grains such that their tunnels are stable. Currently, it is unclear how ants use their limited information about the environment to construct lasting tunnels. We attempt to unearth the ants’ tunneling algorithm by taking three-dimensional (3D) X-ray computed tomographic imaging (XRCT), in real time, of Pogonomyrmex ant tunnel construction. By capturing the location and shape of each grain in the domain, we characterize the relationship between particle properties and ant decision-making within an accurate, virtual recreation of the experiment. We discover that intergranular forces decrease significantly around ant tunnels due to arches forming within the soil. Due to this force relaxation, any grain the ants pick from the tunnel surface will likely be under low stress. Thus, ants avoid removing grains compressed under high forces without needing to be aware of the force network in the surrounding material. Even more, such arches shield tunnels from high forces, providing tunnel robustness. Finally, we observe that ants tend to dig piecewise linearly downward. These results are a step toward understanding granular tunnel stability in heterogeneous 3D systems. We expect that such findings may be leveraged for robotic excavation.

Circulation ◽  
2006 ◽  
Vol 113 (2) ◽  
pp. 186-194 ◽  
Author(s):  
Jun Dong ◽  
Hugh Calkins ◽  
Stephen B. Solomon ◽  
Shenghan Lai ◽  
Darshan Dalal ◽  
...  

Author(s):  
Brandon Lane ◽  
Ho Yeung

This document provides details on the files available in the dataset “Overhang Part X4” pertaining to a three-dimensional (3D) additive manufacturing (AM) build performed on the Additive Manufacturing Metrology Testbed (AMMT) by Ho Yeung and Brandon Lane on June 28, 2019. The files include the input command files, materials data, in-situ process monitoring data, and metadata. This data is one of a set of “AMMT Process Monitoring Datasets”, as part of the Metrology for Real-Time Monitoring of Additive Manufacturing project at the National Institute of Standards and Technology (NIST). Ex-situ part characterization data, including X-ray computed tomography (XCT) measurements, will be provided as it is made available. Readers should refer to the AMMT datasets web page for updates.


2010 ◽  
Vol 151 (21) ◽  
pp. 854-863 ◽  
Author(s):  
Attila Nemes ◽  
Marcel L. Geleijnse ◽  
Osama I. I. Soliman ◽  
Wim B. Vletter ◽  
Jackie S. McGhie ◽  
...  

Jelenleg az echokardiográfia a legszéleskörűbben alkalmazott rutin noninvazív diagnosztikus eljárás, amelynek segítségével a mitralis billentyű morfológiája és funkciója jellemezhető. Ennek az összefoglaló jellegű közleménynek a célja az egyik legújabb echokardiográfiás fejlesztés, a transthoracalis real-time háromdimenziós echokardiográfia szerepének bemutatása a mitralis billentyű vizsgálatában.


Author(s):  
Abdelkrim Merah ◽  
Ridha Kelaiaia ◽  
Faiza Mokhtari

Abstract The Taylor-Couette flow between two rotating coaxial cylinders remains an ideal tool for understanding the mechanism of the transition from laminar to turbulent regime in rotating flow for the scientific community. We present for different Taylor numbers a set of three-dimensional numerical investigations of the stability and transition from Couette flow to Taylor vortex regime of a viscous incompressible fluid (liquid sodium) between two concentric cylinders with the inner one rotating and the outer one at rest. We seek the onset of the first instability and we compare the obtained results for different velocity rates. We calculate the corresponding Taylor number in order to show its effect on flow patterns and pressure field.


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