Decoupling small-scale roughness and long-range features on deep reactive ion etched silicon surfaces

2013 ◽  
Vol 114 (11) ◽  
pp. 113506 ◽  
Author(s):  
Frank W. DelRio ◽  
Lawrence H. Friedman ◽  
Michael S. Gaither ◽  
William A. Osborn ◽  
Robert F. Cook
Keyword(s):  
Long Range ◽  
Silicon Surfaces ◽  
Small Scale ◽  
Etched Silicon ◽  
Scale Roughness

Inferring Earth’s discontinuous chemical layering from the 660-kilometer boundary topography

Science ◽  
2019 ◽  
Vol 363 (6428) ◽  
pp. 736-740 ◽  
Author(s):  
Wenbo Wu ◽  
Sidao Ni ◽  
Jessica C. E. Irving
Keyword(s):  
Solid Earth ◽  
Long Range ◽  
Upper Mantle ◽  
Lower Mantle ◽  
Seismic Waves ◽  
Short Length ◽  
Small Scale ◽  
Length Scale ◽  
Scale Roughness ◽  
Topographic Variation

Topography, or depth variation, of certain interfaces in the solid Earth can provide important insights into the dynamics of our planet interior. Although the intermediate- and long-range topographic variation of the 660-kilometer boundary between Earth’s upper and lower mantle is well studied, small-scale measurements are far more challenging. We found a surprising amount of topography at short length scale along the 660-kilometer boundary in certain regions using scatteredP'P'seismic waves. Our observations required chemical layering in regions with high short-scale roughness. By contrast, we did not see such small-scale topography along the 410-kilometer boundary in the upper mantle. Our findings support the concept of partially blocked or imperfect circulation between the upper and lower mantle.

Enhanced Boiling on Microconfigured Surfaces

1989 ◽  
Vol 111 (2) ◽  
pp. 112-120 ◽  
Author(s):  
N. Wright ◽  
B. Gebhart
Keyword(s):  
Heat Transfer ◽  
Pool Boiling ◽  
Electrical Potential ◽  
Silicon Surfaces ◽  
Electrical Heating ◽  
Experimental Procedure ◽  
Saturated Water ◽  
Etched Silicon ◽  
Convection Correlation ◽  
Enhanced Boiling

New results are presented for pool boiling from vertical, smooth and regularly microconfigured etched silicon surfaces, in saturated water at 1 atm. All specimens were 1.27 cm square and approximately 300 μm thick. The etched microstructures were hexagonal dimples and rectangular trenches. The dimples were 4.1 μm deep and 11.5 μm across, on 22 μm centers. The trenches were 51 μm deep, 12.6 μm wide and 101 μm long, with repeat distances of 22 and 110 μm, in the two directions. The surface densities of the microstructures were 2 × 105 per cm2 for the dimples and 0.4 × 105 per cm2 for the trenches. Electrical heating was accomplished by applying an electrical potential across the phosphorous doped dry side of the silicon specimen substrate. The hexagonally dimpled specimen in the nominal nucleate pool boiling region had heat transfer increased by a factor of 4.2 over that of the smooth specimens. The heat transfer enhancement was a factor of 3.1 over the smooth specimen data, for the trenched specimen data. In the nominally convective-vaporization regime, both the smooth and microconfigured specimens had as much as 5 times the heat transfer compared to a uniform flux natural convection correlation. Comparable heat transfer measurements in subcooled water verified the experimental procedure and also indicated that only a small fraction of this large enhancement may be explained by edge effects, on these small heaters.

scholarly journals Electrostatic forces alter particle size distributions in atmospheric dust

2020 ◽  
Vol 20 (5) ◽  
pp. 3181-3190 ◽  
Author(s):  
Joseph R. Toth III ◽  
Siddharth Rajupet ◽  
Henry Squire ◽  
Blaire Volbers ◽  
Jùn Zhou ◽  
...  
Keyword(s):  
Electric Field ◽  
Size Distribution ◽  
Long Range ◽  
Electric Fields ◽  
Electrostatic Force ◽  
Small Scale ◽  
Size Distributions ◽  
Electrostatic Forces ◽  
Atmospheric Dust ◽  
Airborne Dust

Abstract. Large amounts of dust are lofted into the atmosphere from arid regions of the world before being transported up to thousands of kilometers. This atmospheric dust interacts with solar radiation and causes changes in the climate, with larger-sized particles having a heating effect, and smaller-sized particles having a cooling effect. Previous studies on the long-range transport of dust have found larger particles than expected, without a model to explain their transport. Here, we investigate the effect of electric fields on lofted airborne dust by blowing sand through a vertically oriented electric field, and characterizing the size distribution as a function of height. We also model this system, considering the gravitational, drag, and electrostatic forces on particles, to understand the effects of the electric field. Our results indicate that electric fields keep particles suspended at higher elevations and enrich the concentration of larger particles at higher elevations. We extend our model from the small-scale system to long-range atmospheric dust transport to develop insights into the effects of electric fields on size distributions of lofted dust in the atmosphere. We show that the presence of electric fields and the resulting electrostatic force on charged particles can help explain the transport of unexpectedly large particles and cause the size distribution to become more uniform as a function of elevation. Thus, our experimental and modeling results indicate that electrostatic forces may in some cases be relevant regarding the effect of atmospheric dust on the climate.

Reverberation Intensity Decaying in Range-Dependent Waveguide

2019 ◽  
Vol 27 (03) ◽  
pp. 1950007
Author(s):  
J. R. Wu ◽  
T. F. Gao ◽  
E. C. Shang
Keyword(s):  
Large Scale ◽  
Back Propagation ◽  
Normal Modes ◽  
Small Scale ◽  
Signal Pulse ◽  
First Order ◽  
Orthogonal Property ◽  
Short Signal ◽  
Scale Roughness ◽  
Special Case

In this paper, an analytic range-independent reverberation model based on the first-order perturbation theory is extended to range-dependent waveguide. This model considers the effect of bottom composite roughness: small-scale bottom rough surface provides dominating energy for reverberation, whereas large-scale roughness has the effect of forward and back propagation. For slowly varying bottom and short signal pulse, analytic small-scale roughness backscattering theory is adapted in range-dependent waveguides. A parabolic equation is used to calculate Green functions in range-dependent waveguides, and the orthogonal property of local normal modes is employed to estimate the modal spectrum of PE field. Synthetic tests demonstrate that the proposed reverberation model works well, and it can also predict the reverberation of range-independent waveguide as a special case.

scholarly journals The significant impact of ribs and small-scale roughness on cylinder drag crisis

2020 ◽  
Vol 202 ◽  
pp. 104192 ◽  
Author(s):  
Arne Kilvik Skeide ◽  
Lars Morten Bardal ◽  
Luca Oggiano ◽  
R. Jason Hearst
Keyword(s):  
Small Scale ◽  
Scale Roughness ◽  
Cylinder Drag

Osteoblast-like cell response to calcium phosphate coating chemistry and morphology on etched silicon surfaces

2012 ◽  
Vol 23 (3) ◽  
pp. 835-851 ◽  
Author(s):  
George A. Burke ◽  
Chris J. Rea ◽  
Fergal G. Horgan ◽  
Marie Turkington ◽  
Adrian R. Boyd ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Cell Response ◽  
Silicon Surfaces ◽  
Calcium Phosphate Coating ◽  
Phosphate Coating ◽  
Etched Silicon

scholarly journals Electrostatic forces alter particle size distributions in atmospheric dust

2019 ◽  
Author(s):  
Joseph R. Toth III ◽  
Siddharth Rajupet ◽  
Henry Squire ◽  
Blaire Volbers ◽  
Jùn Zhou ◽  
...  
Keyword(s):  
Electric Field ◽  
Size Distribution ◽  
Long Range ◽  
Electric Fields ◽  
Electrostatic Force ◽  
Small Scale ◽  
Size Distributions ◽  
Electrostatic Forces ◽  
Atmospheric Dust ◽  
Airborne Dust

Abstract. Large amounts of dust are lofted into the atmosphere from arid regions of the world before being transported up to thousands of kilometers. This atmospheric dust interacts with solar radiation causing changes in the climate, with larger-sized particles having a heating effect, and smaller-sized particles having a cooling effect. Previous studies on the long-range transport of dust have found larger particles than expected, without a model to explain their transport. Here, we investigate the effect of electric fields on lofted airborne dust by blowing sand through a vertically-oriented electric field, and characterizing the size distribution as a function of height. We also model this system, considering the gravitational, drag, and electrostatic forces on particles, to understand the effects of the electric field. Our results indicate that electric fields keep particles suspended at higher elevations and enrich the concentration of larger particles at higher elevations. We extend our model from the small-scale system to long-range atmospheric dust transport to develop insights on the effects of electric fields on size distributions of lofted dust in the atmosphere. We show that the presence of electric fields and the resulting electrostatic force on particles can help explain the transport of unexpectedly larger particles and cause the size distribution to become more uniform as a function of elevation. Thus, our experimental and modelling results indicate that electrostatic forces should be considered when determining the effect of atmospheric dust on the climate.

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