scholarly journals Corrugation of an unpaved road surface under vehicle weight

2020 ◽  
Vol 476 (2241) ◽  
pp. 20200323
Author(s):  
C. Matsuyama ◽  
Y. Tanaka ◽  
M. Sato ◽  
H. Shima
Keyword(s):  
Experimental Data ◽  
Flat Surface ◽  
Heavy Traffic ◽  
Vertical Oscillation ◽  
Soil Consolidation ◽  
Unpaved Road ◽  
Moving Vehicles ◽  
Growth Phenomenon ◽  
Road Surfaces ◽  
Underlying Soil

Road corrugation refers to the formation of periodic, transverse ripples on unpaved road surfaces. It forms spontaneously on an initially flat surface under heavy traffic and can be considered to be a type of unstable growth phenomenon, possibly caused by the local volume contraction of the underlying soil due to a moving vehicle’s weight. In the present work, we demonstrate a possible mechanism for road corrugation using experimental data of soil consolidation and numerical simulations. The results indicate that the vertical oscillation of moving vehicles, which is excited by the initial irregularities of the surface, plays a key role in the development of corrugation.

Patterns and quasi-patterns in the Faraday experiment

1994 ◽  
Vol 278 ◽  
pp. 123-148 ◽  
Author(s):  
W. S. Edwards ◽  
S. Fauve
Keyword(s):  
Flat Surface ◽  
Vertical Oscillation ◽  
Two Dimensional ◽  
Large Aspect Ratio ◽  
Amplitude Equations ◽  
Parallel Lines ◽  
Small Depth ◽  
Faraday Instability ◽  
Wave Patterns ◽  
Frequency Ratios

Parametric excitation of surface waves via forced vertical oscillation of a container filled with fluid (the Faraday instability) is investigated experimentally in a small-depth large-aspect-ratio system, with a viscous fluid and with two simultaneous forcing frequencies. The asymptotic pattern observed just above the threshold for the first instability of the flat surface is found to depend strongly on the frequency ratio and the amplitudes and phases of the two sinusoidal components of the driving acceleration. Parallel lines, squares, and hexagons are observed. With viscosity 100 cS, these stable standing-wave patterns do not exhibit strong sidewall effects, and are found in containers of various shapes including an irregular shape. A ‘quasi-pattern’ of twelvefold symmetry, analogous to a two-dimensional quasi-crystal, is observed for some even/odd frequency ratios. Many of the experimental phenomena can be modelled via cubic-order amplitude equations derived from symmetry arguments.

Modeling Soil Detachment on Unpaved Road Surfaces on the Loess Plateau

2011 ◽  
Vol 54 (4) ◽  
pp. 1377-1384 ◽  
Author(s):  
L.-X. Cao ◽  
K.-L. Zhang ◽  
H.-L. Dai ◽  
Z.-L. Guo
Keyword(s):  
Loess Plateau ◽  
The Loess Plateau ◽  
Unpaved Road ◽  
Road Surfaces

The Design of Radar Speed-Measuring and Monitoring System Based on DSP

2011 ◽  
Vol 71-78 ◽  
pp. 4435-4439
Author(s):  
Jie Jia ◽  
Huan Ling ◽  
He Huang ◽  
Jian Yong Lai ◽  
Gen Hua Zhang
Keyword(s):  
Experimental Data ◽  
Monitoring System ◽  
Frequency Spectrum ◽  
Doppler Effect ◽  
Continuous Wave ◽  
Experimental Platform ◽  
Measuring Accuracy ◽  
Moving Vehicles ◽  
Wave Radar ◽  
To Receive

To reduce the accident, a radar speed measuring and monitoring system based on DSP chip-TMS320F2812 is designed in this paper. Continuous wave radar is used to receive echoes which are reflected from moving vehicles and frequency spectrum is analyzed with FFT. And then, velocity is calculated with the Doppler effect formula. Finally, the velocity is uploaded to the monitoring center by RS-232 UART. An experimental platform is produced and do the experiment by this method, simulation and experimental data show that it is an effective way to improve the speed-measuring accuracy and reduce accident rates.

CFD for Jet Impingement Heat Transfer With Single Jets and Arrays

2005 ◽  
Author(s):  
Mounir B. Ibrahim ◽  
Bejoy J. Kochuparambil ◽  
Srinath V. Ekkad ◽  
Terrence W. Simon
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Flat Surface ◽  
Turbulent Transport ◽  
Jet Impingement ◽  
Target Plate ◽  
Plate Spacing ◽  
Multiple Jets ◽  
Single Jet ◽  
Jet Axis

CFD experiments were conducted for heat transfer with jet impingement over solid surfaces. The parameters include: 1) Jet Reynolds number from 3,000 to 23,000, 2) Jet-to-target-plate spacing (z/d), from 2 to 14 (single jet), d is jet diameter, 3) Target plate shape: 3a) flat, 3b) concave, 3c) convex, (single jet), 4) One row of seven jets impinging on a flat surface, the channel has one end closed (at 24d away from the most upstream jet axis), 5) Three rows of seven jets each in-line arrangement impinging on a flat surface, the channel has one end closed (at 24d away from the most upstream jet axis). Four CFD models (utilizing FLUENT commercial code) have been considered: 1) laminar flow (no turbulent transport), and turbulent flow with turbulence modeling by 2) the standard k–ε model, 3) the k–ω model, and 4) the v2–f model. The predictions of Nu number for each case were compared with experimental data available from the literature. It is shown that the v2–f model gives the best overall performance, though the k–ω model gives good predictions for most of the flow, with the exception of near the stagnation zone for some cases. The models are in much better agreement (with the data) as z/d grows and at larger radial locations from the jet axis, as expected. For multiple jets in one row (z/d = 2), again the v2–f showed the best overall agreement with the experimental data. The k–ω model is not as good while k–ε clearly overpredicts the Nusselt numbers. For multiple jets in three inline rows (z/d = 5), all the three models were in overall agreement with the experimental data. However, k–ε and k–ω exhibit an important phenomenon, reported by the experiments: a decrease of the stagnation Nu from the upstream jet to the downstream ones. The v2–f model did not reproduce this feature.

Calculation of Turbulent Boundary Layer for a Slot Jet Impingement on a Flat Surface

2014 ◽  
Author(s):  
H. Arabnejad ◽  
A. Mansouri ◽  
S. A. Shirazi ◽  
B. S. McLaury
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Flat Surface ◽  
Jet Impingement ◽  
Turbulent Jets ◽  
Integral Form ◽  
Shear Stresses ◽  
Submerged Jet ◽  
Flow Parameters ◽  
Wall Shear

The objective of this study is to characterize flow parameters for two-dimensional turbulent jets impinging on a flat surface. An integral form of the momentum equation has been used to obtain a hydrodynamic solution. The boundary layer was divided into three regions, stagnation zone, developing zone and fully developed zone for free-surface and free shear, and into two regions, stagnation and wall jet zone for submerged jet configurations. A nonlinear ordinary differential equation has been obtained for frictional velocity at each zone using a logarithmic velocity profile with Coles’s law of the wake and solved numerically to predict wall shear stress as well as boundary layer and momentum thicknesses. The proposed method is more straightforward and computationally less expensive in calculating the main flow parameters as compared to turbulent flow models such as RANS and LES. Predicted wall shear stresses for a submerged jet were compared to experimental data for different cases and showed agreement with experimental data.

Microdiffraction Patterns of Small Metallic Particles II; Theoretical Analysis

1982 ◽  
Vol 40 ◽  
pp. 668-669
Author(s):  
A. Gómez ◽  
P. Schabes-Retchkiman ◽  
M. José-Yacamán ◽  
T. Ocaña
Keyword(s):  
Experimental Data ◽  
Electron Diffraction ◽  
Theoretical Analysis ◽  
Size Range ◽  
Dynamical Theory ◽  
Metallic Particles ◽  
Splitting Effect

The splitting effect that is observed in microdiffraction pat-terns of small metallic particles in the size range 50-500 Å can be understood using the dynamical theory of electron diffraction for the case of a crystal containing a finite wedge. For the experimental data we refer to part I of this work in these proceedings.

Evidence for ordered Fe3Ni

1987 ◽  
Vol 45 ◽  
pp. 216-217
Author(s):  
K.B. Reuter ◽  
D.B. Williams ◽  
J.I. Goldstein
Keyword(s):  
Experimental Data ◽  
Martensitic Transformation ◽  
Electron Diffraction ◽  
Room Temperature ◽  
Direct Evidence ◽  
Transformation Product ◽  
Iron Meteorites ◽  
X Ray ◽  
Ni Content ◽  
Temperature Transformation

In the Fe-Ni system, although ordered FeNi and ordered Ni3Fe are experimentally well established, direct evidence for ordered Fe3Ni is unconvincing. Little experimental data for Fe3Ni exists because diffusion is sluggish at temperatures below 400°C and because alloys containing less than 29 wt% Ni undergo a martensitic transformation at room temperature. Fe-Ni phases in iron meteorites were examined in this study because iron meteorites have cooled at slow rates of about 10°C/106 years, allowing phase transformations below 400°C to occur. One low temperature transformation product, called clear taenite 2 (CT2), was of particular interest because it contains less than 30 wtZ Ni and is not martensitic. Because CT2 is only a few microns in size, the structure and Ni content were determined through electron diffraction and x-ray microanalysis. A Philips EM400T operated at 120 kV, equipped with a Tracor Northern 2000 multichannel analyzer, was used.

Scanned tip measurement of deep vertical facets on a flat surface: Measuring roughness on gaas laser waveguide mirrors

1993 ◽  
Vol 51 ◽  
pp. 532-533
Author(s):  
Chang Shen ◽  
Phil Fraundorf ◽  
Robert W. Harrick
Keyword(s):  
Integrated Circuits ◽  
Flat Surface ◽  
Scanning Force Microscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Optoelectronic Integrated Circuits ◽  
Laser Waveguide ◽  
Scanning Force ◽  
Gaas Laser

Monolithic integration of optoelectronic integrated circuits (OEIC) requires high quantity etched laser facets which prevent the developing of more-highly-integrated OEIC's. The causes of facet roughness are not well understood, and improvement of facet quality is hampered by the difficulty in measuring the surface roughness. There are several approaches to examining facet roughness qualitatively, such as scanning force microscopy (SFM), scanning tunneling microscopy (STM) and scanning electron microscopy (SEM). The challenge here is to allow more straightforward monitoring of deep vertical etched facets, without the need to cleave out test samples. In this presentation, we show air based STM and SFM images of vertical dry-etched laser facets, and discuss the image acquisition and roughness measurement processes. Our technique does not require precision cleaving. We use a traditional tip instead of the T shape tip used elsewhere to preventing “shower curtain” profiling of the sidewall. We tilt the sample about 30 to 50 degrees to avoid the curtain effect.

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