scholarly journals A Light-Weight Vibrational Motor Powered Recoil Robot That Hops Rapidly Across Granular Media

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Alice C. Quillen ◽  
Randal C. Nelson ◽  
Hesam Askari ◽  
Kathryn Chotkowski ◽  
Esteban Wright ◽  
...  
Keyword(s):  
Numerical Model ◽  
Froude Number ◽  
Drag Force ◽  
Granular Media ◽  
Low Cost ◽  
Period Doubling ◽  
Light Weight ◽  
Two Dimensional ◽  
Ball Bouncing ◽  
Vibrating Table

Abstract A 1-cm coin vibrational motor fixed to the center of a 4-cm square foam platform moves rapidly across granular media at a speed of up to 30 cm/s or about 5 body lengths/s. Fast speeds are achieved with dimensionless acceleration number, similar to a Froude number, up to 50, allowing the light-weight 1.4 g mechanism to remain above the substrate, levitated and propelled by its kicks off the surface. The mechanism is low cost and moves across granular media without any external moving parts. With 2-s exposure, we photograph the trajectory of the mechanism with an LED fixed to the mechanism. Trajectories can exhibit period doubling phenomena similar to a ball bouncing on a vibrating table top. A two-dimensional robophysics model is developed to predict mechanism trajectories. We find that a vertical drag force is required in the model to match the height above the surface reached by the mechanism. We attribute the vertical drag force to suction from air flow below the mechanism base and through the granular substrate. Our numerical model suggests that horizontal speed is maximized when the mechanism is prevented from jumping high off the surface. In this way, the mechanism resembles a galloping or jumping animal whose body remains nearly at the same height above the ground during its gait. Our mechanism and model illustrate that speed and efficiency of light-weight hoppers on granular media can be affected by aerodynamics and substrate permeability.

Euler–Lagrange Two-Phase Model for Simulating Live-Bed Scour Beneath Marine Pipelines

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
A. Yeganeh-Bakhtiary ◽  
M. Zanganeh ◽  
E. Kazemi ◽  
L. Cheng ◽  
A. K. Abd Wahab
Keyword(s):  
Numerical Model ◽  
Granular Media ◽  
Fluid Shear Stress ◽  
Distinct Element ◽  
Fluid Phase ◽  
Point Of View ◽  
Two Dimensional ◽  
Two Phase ◽  
Drag Forces ◽  
Bed Scour

In this study, an Euler–Lagrange coupling two-phase flow model, namely movable bed simulator (MBS)-two-dimensional (2D) model was employed to explore the current-induced live-bed scour beneath marine pipelines. The fluid phase characteristics, such as velocity and pressure, were obtained by the Reynolds-averaged Navier–Stokes (RANS) equations with a k-ε turbulence closure model in a two-dimensional Eulerian grid, whereas the seabed beneath pipelines was traced as an assembly of discrete sand grains from the Lagrangian point of view. The live-bed scour was evolved as the motion of a granular media based on distinct element method (DEM) formulation, in which the frequent interparticle collision was described with a spring and dashpot system. The fluid flow was coupled to the sediment phase, considering the acting drag forces between. Comparison between the numerical result and experimental measurement confirms that the numerical model successfully estimates the bed profile and flow velocity field. It is evident that the fluid shear stress decreases with the increasing of gap ratio e/D. The numerical model provides a useful approach to improve mechanistic understanding of hydrodynamic and sediment transport in live-bed scour beneath a marine pipeline.

Ti3C2-MXene/Bismuth Ferrite Nanohybrids for Efficient Degradation of Organic Dye and Colorless Pollutant

2019 ◽  
Author(s):  
Ayesha Tariq ◽  
M. Abdullah Iqbal ◽  
S. Irfan Ali ◽  
Muhammad Z. Iqbal ◽  
Deji Akinwande ◽  
...  
Keyword(s):  
Surface Area ◽  
Low Cost ◽  
Bismuth Ferrite ◽  
Organic Dye ◽  
Two Dimensional ◽  
Electron Hole ◽  
Photocatalytic Application ◽  
Electron Hole Pair ◽  
Pair Generation ◽  
Photocatalytic Applications

<p>Nanohybrids, made up of Bismuth ferrites/Carbon allotropes, are extensively used in photocatalytic applications nowadays. Our work proposes a nanohybrid system composed of Bismuth ferrite nanoparticles with two-dimensional (2D) MXene sheets namely, the BiFeO<sub>3</sub> (BFO)/Ti<sub>3</sub>C<sub>2</sub> (MXene) nanohybrid for enhanced photocatalytic activity. We have fabricated the BFO/MXene nanohybrid using simple and low cost double solvent solvothermal method. The SEM and TEM images show that the BFO nanoparticles were attached onto the MXene surface and in the inter-layers of two-dimensional (2D) MXene sheets. The photocatalytic application is tested for the visible light irradiation which showed the highest efficiency among all pure-BFO based photocatalysts, i.e. 100% degradation in 42 min for organic dye (Congo Red) and colorless aqueous pollutant (acetophenone) in 150 min, respectively. The present BFO-based hybrid system exhibited the large surface area of 147 m<sup>2</sup>g<sup>-1</sup>measured via Brunauer-Emmett-Teller (BET) sorption-desorption technique, and is found to be largest among BFO and its derivatives. Also, the photoluminescence (PL) spectra indicate large electron-hole pair generation. Fast and efficient degradation of organic molecules is supported by both factors; larger surface area and lower electron-hole recombination rate. The BFO/MXene nanohybrid presented here is a highly efficient photocatalyst compared to other nanostructures based on pure BiFeO<sub>3</sub> which makes it a promising candidate for many future applications.</p>

Investigation of two-dimensional nonstationary processes of outflow a gas-saturated liquid from axisymmetric vessels

2012 ◽  
Vol 9 (1) ◽  
pp. 47-52
Author(s):  
R.Kh. Bolotnova ◽  
V.A. Buzina
Keyword(s):  
Comparative Analysis ◽  
Numerical Model ◽  
Liquid Mixture ◽  
Phase Model ◽  
Test Problems ◽  
Two Dimensional ◽  
Nonstationary Processes ◽  
Saturated Liquid ◽  
Two Phase ◽  
One Dimensional

The two-dimensional and two-phase model of the gas-liquid mixture is constructed. The validity of numerical model realization is justified by using a comparative analysis of test problems solution with one-dimensional calculations. The regularities of gas-saturated liquid outflow from axisymmetric vessels for different geometries are established.

Fused Ambipolar Aza-isoindigos with NIR absorption

2021 ◽  
Author(s):  
Liping Yao ◽  
Danlei Zhu ◽  
Hailiang Liao ◽  
Sheik Haseena ◽  
Mahesh kumar Ravva ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
High Performance ◽  
Low Cost ◽  
Light Weight ◽  
The Past ◽  
Pi Conjugated ◽  
Nir Absorption ◽  
Conjugated Organic Semiconductors

Due to their advantages of low-cost, light-weight, and mechanical flexibility, much attention has been focused on pi-conjugated organic semiconductors. In the past decade, although many materials with high performance has...

scholarly journals Microfabrication with Very Low-Average Power of Green Light to Produce PDMS Microchips

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 607
Author(s):  
Lucero M. Hernandez-Cedillo ◽  
Francisco G. Vázquez-Cuevas ◽  
Rafael Quintero-Torres ◽  
Jose L. Aragón ◽  
Miguel Angel Ocampo Mortera ◽  
...  
Keyword(s):  
Low Cost ◽  
Average Power ◽  
Green Light ◽  
Microfluidic Devices ◽  
Processing Parameters ◽  
Coating Film ◽  
Two Dimensional ◽  
Dimethyl Siloxane ◽  
Visible Laser ◽  
High Absorption

In this article, we show an alternative low-cost fabrication method to obtain poly(dimethyl siloxane) (PDMS) microfluidic devices. The proposed method allows the inscription of micron resolution channels on polystyrene (PS) surfaces, used as a mold for the wanted microchip’s production, by applying a high absorption coating film on the PS surface to ablate it with a focused low-power visible laser. The method allows for obtaining micro-resolution channels at powers between 2 and 10 mW and can realize any two-dimensional polymeric devices. The effect of the main processing parameters on the channel’s geometry is presented.

scholarly journals Influence of the North Branch of the Qingshuigou River on the Lower Reaches of Yellow River Based on Two-dimensional Numerical Model

2021 ◽  
Vol 1885 (2) ◽  
pp. 022043
Author(s):  
Caodong Jiang ◽  
Liangchao Ma ◽  
Dongfeng Li ◽  
Hongwu Zhang ◽  
Zihao Li
Keyword(s):  
Numerical Model ◽  
Yellow River ◽  
Two Dimensional ◽  
The North
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