The moire crack gauges on the crown of the Frank Slide

1990 ◽  
Vol 27 (6) ◽  
pp. 835-840 ◽  
Author(s):  
B. Kostak ◽  
D. M. Cruden
Keyword(s):  
Key Words ◽  
Measurement System ◽  
Rock Block ◽  
Reliable Measurement ◽  
Long Time ◽  
Moire Fringe ◽  
Time Periods ◽  
Moiré Fringe

Two TM71 Crack Monitors installed in a gaping crack in the crown of the Frank Slide, Alberta, have recorded movements of less than 1 mm/year. These movements are attributed to continuing dilation of the rock block field in the crown. The crack monitors' moire fringe measurement system is particularly suited to the reliable measurement of small movements over long time periods. Key words: displacements, monitoring, rock, Rockies, creep, interferometry.

Use of tilt sensing equipment for monitoring long-term bridge movement

1991 ◽  
Vol 18 (6) ◽  
pp. 1033-1046 ◽  
Author(s):  
Terry J. Wipf
Keyword(s):  
Key Words ◽  
Reference Point ◽  
Structural Engineering ◽  
Field Tests ◽  
Measurement Instruments ◽  
Time Period ◽  
Long Time ◽  
Time Periods ◽  
Tilt Sensors

Accurate monitoring of long-term movements in bridges can be difficult primarily because of the relatively long time period over which the movements occur and inadequate instrumentation and technique. A stable reference point for measurements is difficult to obtain over these long time periods. Two bridges were monitored for long-term structural movement; the results are presented here. Instrumentation including temperature transducers and tilt sensors placed on and near piers determined the pier movement. The results of the study indicate that a superstructure expansion pier on one of the bridges monitored actually behaved as a fixed pier. The equipment used in the study, including data acquisition components and tilt sensors, proved reliable and accurate. Key words: bridges, girder, field tests, foundations, measurement instruments, piers, structural engineering.

Simulation and Contrast Analysis of tem Images of Cracks

1990 ◽  
Vol 48 (1) ◽  
pp. 578-579
Author(s):  
D. Goyal ◽  
A. H. King
Keyword(s):  
Displacement Vector ◽  
Crack Tip ◽  
Perfect Crystal ◽  
Operating Conditions ◽  
Displacement Fields ◽  
Fringe Contrast ◽  
Orthogonal Geometry ◽  
Moire Fringe ◽  
Moiré Fringe

TEM images of cracks have been found to give rise to a moiré fringe type of contrast. It is apparent that the moire fringe contrast is observed because of the presence of a fault in a perfect crystal, and is characteristic of the fault geometry and the diffracting conditions in the TEM. Various studies have reported that the moire fringe contrast observed due to the presence of a crack in an otherwise perfect crystal is distinctive of the mode of crack. This paper describes a technique to study the geometry and mode of the cracks by comparing the images they produce in the TEM because of the effect that their displacement fields have on the diffraction of electrons by the crystal (containing a crack) with the corresponding theoretical images. In order to formulate a means of matching experimental images with theoretical ones, displacement fields of dislocations present (if any) in the vicinity of the crack are not considered, only the effect of the displacement field of the crack is considered.The theoretical images are obtained using a computer program based on the two beam approximation of the dynamical theory of diffraction contrast for an imperfect crystal. The procedures for the determination of the various parameters involved in these computations have been well documented. There are three basic modes of crack. Preliminary studies were carried out considering the simplest form of crack geometries, i. e., mode I, II, III and the mixed modes, with orthogonal crack geometries. It was found that the contrast obtained from each mode is very distinct. The effect of variation of operating conditions such as diffracting vector (), the deviation parameter (ω), the electron beam direction () and the displacement vector were studied. It has been found that any small change in the above parameters can result in a drastic change in the contrast. The most important parameter for the matching of the theoretical and the experimental images was found to be the determination of the geometry of the crack under consideration. In order to be able to simulate the crack image shown in Figure 1, the crack geometry was modified from a orthogonal geometry to one with a crack tip inclined to the original crack front. The variation in the crack tip direction resulted in the variation of the displacement vector also. Figure 1 is a cross-sectional micrograph of a silicon wafer with a chromium film on top, showing a crack in the silicon.

An automatic high-speed scanner for moiré fringe techniques

1972 ◽  
Vol 7 (2) ◽  
pp. 151-156 ◽  
Author(s):  
D J Hitchings ◽  
A R Luxmoore
Keyword(s):  
High Speed ◽  
Peak Detection ◽  
Optical Signal ◽  
Single Line ◽  
Scanning System ◽  
Moiré Fringes ◽  
Moire Fringe ◽  
Scanning Line ◽  
Moiré Fringe

A high-speed scanning system has been developed to locate the centres of moiré fringes along any single line. The system comprises a rotating-mirror scanner for conversion of an optical signal to electrical; this conversion is followed by peak detection, storage, and print-out electronics. Up to 20 fringes can be scanned in 1 ms. The results are printed in terms of fringe separations along the scanning line.

Motivation factors behind secession in the Arab states

2021 ◽  
Vol 28 ◽  
Keyword(s):  
Key Words ◽  
Ethnic Minorities ◽  
International Support ◽  
Motivation Factors ◽  
The Future ◽  
Long Time ◽  
Arab States ◽  
Political Economic

Some countries might witness movements that call for secession from the main homeland ,some had succeeded in their endeavors and others are hoping to accomplish them in the future .There are such movements in the Arab homeland which varied according to the motivations behind their wishes to disengage and the means that they used to accomplish them ,whether peaceful or by resort to violence ,which might take long time . These motives might be political, ethnical ,religious, or else . Usually there might be more than one motive behind such moves towards disengagement and secession, but the international support is the most conclusive factor in achieving such an aim , and this is what we are trying to discuss here. Key words : secession ,political, economic ,ethnic, minorities

scholarly journals Reproducible strain measurement in electronic devices by applying integer multiple to scanning grating in scanning moiré fringe imaging

AIP Advances ◽  
2014 ◽  
Vol 4 (10) ◽  
pp. 107107 ◽  
Author(s):  
Suhyun Kim ◽  
Younheum Jung ◽  
Joong Jung Kim ◽  
Sunyoung Lee ◽  
Haebum Lee ◽  
...  
Keyword(s):  
Strain Measurement ◽  
Electronic Devices ◽  
Integer Multiple ◽  
Moire Fringe ◽  
Moiré Fringe
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