Experimental Investigation Into Plugging of Open Ended Piles

2009 ◽  
Author(s):  
Jelke Dijkstra ◽  
Wout Broere
Keyword(s):  
Stress Ratio ◽  
Local Stress ◽  
Absolute Magnitude ◽  
Horizontal Stress ◽  
Pile Head ◽  
Phase Stepping ◽  
Index Matching ◽  
Model Pile ◽  
Refractive Index Matching ◽  
Photoelastic Data

This paper presents the results of a model pile test in a transparent photoelastic medium. This medium is composed of crushed glass particles in a refractive index matching liquid. The test setup allows for quantitative photoelastic measurements. For the measurement of the photoelastic data the phase stepping technique is used. Stresses in the granular medium located next to and in the plug were recorded at varying installation depths of the pile during monotonic jacking of the transparent pile in combination with the pile head load. The horizontal stress ratio in the plug for this particular test is found to be equal to the vertical stress. A distinct stress arch below the pile base is observed during penetration. The high local stress increase in and below the plug move with the pile as the plug travels downward into the soil and do not change much in absolute magnitude.

A Study of Strain and Strain-Rate Dependent Properties of a Superplastic Zn-Al Alloy Under Biaxial Stresses

1982 ◽  
Vol 104 (1) ◽  
pp. 41-46
Author(s):  
T. C. Hsu ◽  
I. M. Bidhendi
Keyword(s):  
Strain Rate ◽  
Stress Ratio ◽  
Local Stress ◽  
Biaxial Stress ◽  
Al Alloy ◽  
Local Geometry ◽  
Forming Process ◽  
Rate Dependent ◽  
Strain And Strain Rate ◽  
Liquid Behavior

A superplastic Zn-Al alloy in sheet form is formed into a bulge over a circular hole by pneumatic pressure. The geometry, the stress, the strain, and the strain-rate are determined at various points covering the whole specimen and at various stages of the forming process. The complicated shape, and its complicated changes, are represented by introducing an index for the local geometry, called “prolateness,” which is also related to the local stress ratio in a simple way. The biaxial stress is analyzed into a strain-proportional and a strain-rate-proportional component, which represent, respectively, the quasi-solid and the quasi-liquid behavior of the superplastic material.

Experimental Characterization of Slug Flow Velocity Distribution in Two Phase Pipe Flow

2009 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Peter Rodgers
Keyword(s):  
Velocity Distribution ◽  
Slug Flow ◽  
Two Phase ◽  
Significant Drop ◽  
Horizontal Pipe ◽  
Measured Velocity ◽  
Air Bubble ◽  
Velocity Magnitude ◽  
Index Matching ◽  
Refractive Index Matching

This paper presents an experimental study of gas-liquid slug flow inside a horizontal pipe. The influence of air bubble passage on liquid flow is characterized using Particle Image Velocimetry (PIV) combined with Refractive Index Matching (RIM) and fluorescent tracers. A physical insight into the velocity distribution within slug flow is presented. It was observed that the slug flow significantly influences the velocity profile in the liquid film. Measured velocity distributions also revealed a significant drop in the velocity magnitude immediately upstream of the slug nose. These findings aim to aid an understanding of the mechanism of solid transportation in slug flows.

scholarly journals Refractive index matching applied to fecal smear clearing

2005 ◽  
Vol 47 (6) ◽  
pp. 347-350 ◽  
Author(s):  
Cláudio S. Ferreira
Keyword(s):  
Refractive Index ◽  
Sucrose Solution ◽  
Glycerol Solution ◽  
Human Feces ◽  
Microscope Slide ◽  
Helminth Eggs ◽  
Index Matching ◽  
Refractive Index Matching ◽  
Fecal Smear ◽  
Effect Of Light

Thick smears of human feces can be made adequate for identification of helminth eggs by means of refractive index matching. Although this effect can be obtained by simply spreading a fleck of feces on a microscope slide, a glycerol solution has been routinely used to this end. Aiming at practicability, a new quantitative technique has been developed. To enhance both sharpness and contrast of the images, a sucrose solution (refractive index = 1.49) is used, which reduces the effect of light-scattering particulates. To each slide a template-measured (38.5 mm³) fecal sample is transferred. Thus, egg counts and sensitivity evaluations are easily made.

scholarly journals Biological glass: structural determinants of eye lens transparency

2011 ◽  
Vol 366 (1568) ◽  
pp. 1250-1264 ◽  
Author(s):  
Steven Bassnett ◽  
Yanrong Shi ◽  
Gijs F. J. M. Vrensen
Keyword(s):  
Refractive Index ◽  
Cellular Level ◽  
Structural Determinants ◽  
Lens Transparency ◽  
Index Matching ◽  
Lens Fibre ◽  
Refractive Index Matching ◽  
Lens Membranes ◽  
Adhesive Proteins ◽  
Structural Adaptations

The purpose of the lens is to project a sharply focused, undistorted image of the visual surround onto the neural retina. The first pre-requisite, therefore, is that the tissue should be transparent. Despite the presence of remarkably high levels of protein, the lens cytosol remains transparent as a result of short-range-order interactions between the proteins. At a cellular level, the programmed elimination of nuclei and other light-scattering organelles from cells located within the pupillary space contributes directly to tissue transparency. Scattering at the cell borders is minimized by the close apposition of lens fibre cells facilitated by a plethora of adhesive proteins, some expressed only in the lens. Similarly, refractive index matching between lens membranes and cytosol is believed to minimize scatter. Refractive index matching between the cytoplasm of adjacent cells is achieved through the formation of cellular fusions that allow the intermingling of proteins. Together, these structural adaptations serve to minimize light scatter and enable this living, cellular structure to function as ‘biological glass’.

scholarly journals Rupture Directivity in 3D Inferred From Acoustic Emissions Events in a Mine-Scale Hydraulic Fracturing Experiment

2021 ◽  
Vol 9 ◽  
Author(s):  
José Ángel López-Comino ◽  
Simone Cesca ◽  
Peter Niemz ◽  
Torsten Dahm ◽  
Arno Zang
Keyword(s):  
Hydraulic Fracturing ◽  
Acoustic Emissions ◽  
Local Stress ◽  
Horizontal Stress ◽  
Monitoring Networks ◽  
Rupture Directivity ◽  
Shallow Subsurface ◽  
Minimum Horizontal Stress ◽  
Directivity Effects ◽  
Full Waveforms

Rupture directivity, implying a predominant earthquake rupture propagation direction, is typically inferred upon the identification of 2D azimuthal patterns of seismic observations for weak to large earthquakes using surface-monitoring networks. However, the recent increase of 3D monitoring networks deployed in the shallow subsurface and underground laboratories toward the monitoring of microseismicity allows to extend the directivity analysis to 3D modeling, beyond the usual range of magnitudes. The high-quality full waveforms recorded for the largest, decimeter-scale acoustic emission (AE) events during a meter-scale hydraulic fracturing experiment in granites at ∼410 m depth allow us to resolve the apparent durations observed at each AE sensor to analyze 3D-directivity effects. Unilateral and (asymmetric) bilateral ruptures are then characterized by the introduction of a parameter κ, representing the angle between the directivity vector and the station vector. While the cloud of AE activity indicates the planes of the hydrofractures, the resolved directivity vectors show off-plane orientations, indicating that rupture planes of microfractures on a scale of centimeters have different geometries. Our results reveal a general alignment of the rupture directivity with the orientation of the minimum horizontal stress, implying that not only the slip direction but also the fracture growth produced by the fluid injections is controlled by the local stress conditions.

scholarly journals Kilowatt-level direct-‘refractive index matching liquid’-cooled Nd:YLF thin disk laser resonator

2016 ◽  
Vol 24 (2) ◽  
pp. 1758 ◽  
Author(s):  
Zhibin Ye ◽  
Chong Liu ◽  
Bo Tu ◽  
Ke Wang ◽  
Qingsong Gao ◽  
...  
Keyword(s):  
Refractive Index ◽  
Thin Disk ◽  
Laser Resonator ◽  
Disk Laser ◽  
Index Matching ◽  
Refractive Index Matching ◽  
Thin Disk Laser
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