Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 26 for “"Speckle Pattern"”.
-
Modal testing using high speed digital speckle pattern interferometry
… introduces the application of a high-speed speckle pattern interferometer (SPI) to perform quantified impact modal testing. The interferometer acts as a non-contact multipoint vibrometer that removes the mass-loading effects of contact transducers to improve measurement accuracy and …
-
Evaluating digital image correlation speckle pattern quality using finite element‑based displacement fields
… that relies on high‑contrast, stochastic speckle patterns to measure surface deformations. Recent research has focused on quantifying speckle pattern quality to improve measurement accuracy, leading to the development of several pattern quality metrics. This study builds on these efforts …
-
Electronic Speckle Pattern Interferometry (ESPI) NDE of cracks in pressure vessels with FEA modelling
… results of an attempt to simulate the Electronic Speckle Pattern Interferometric fringe patterns observed around a crack or combination of cracks in a pressure vessel by finite element methods. Electronic Speckle Pattern Interferometry (ESPI) is a coherent optical measurement technique that …
-
TI Nano Powder Speckle Pattern Creation and Use in DIC of ZnO Modified Single Carbon Fibers
… to use HD DIC for mapping the interface by using speckles in nanoscale. The speckle pattern was created with Ti nano powder for strain maps in the fiber-matrix interface. The main objective of this research was to develop a protocol for speckling the modified single fiber composite and show that …
-
Reduced exposure time as a method of minimising the impact of vibration on electronic speckle pattern interferometry
Includes bibliographical references.
-
Residual Stress Measurements of Unblasted and Sandblasted Mild Steel Specimens Using X-Ray Diffraction, Strain-Gage Hole Drilling, and Electronic Speckle Pattern Interferometry (ESPI) Hole Drilling Methods
… strain-gage hole drilling (SGHD), and electronic speckle pattern interferometry (ESPI) hole drilling, and to validate the new ESPI hole drilling method by comparing its measurement results to those produced by the SGHD method. Both the XRD and SGHD methods were selected because they are accurate …
-
Effect of Vibration of Unconsolidated Sand on the Performance of Interferometric Vibration Sensors
… Laser Doppler vibrometers (LDV) and digital speckle pattern interferometers are studied in this thesis. The working principle of laser Doppler vibrometry and digital shearography is described. The effect of vibration of the unconsolidated sand on the performance of both sensors is …
-
Laser speckle photography for surface tampering detection
… combines computational photography and laser speckle imaging. Without requiring controlled laboratory conditions, our method is able to detect surface changes that would be indistinguishable in regular photographs. It is also mobile and does not need to be present at the time of contact with …
-
Implementation of an Open-Source Digital Image Correlation Software for Structural Testing
… These results were used to calibrate parameters (speckle pattern density, lighting, and camera settings) used with the DIC software. The second stage included pure compression tests on concrete cubes and concrete cylinders to compare the difference in results between: (i) surface curvature, (ii) …
-
Speckle-Messtechniken mit unterschiedlicher Kohärenz zur Diagnostik des mechanischen Verhaltens geschichteter historischer Farbaufträge auf Kulturgütern
… Anwendung und Weiterentwicklung verschiedener Specklemesstechniken mit unterschiedlicher Kohärenz. Der Einsatz dieser Methoden dient der Beurteilung der Festigung geschichteter Farbaufträge auf Fragmenten aus der Terrakotta-Armee des Ersten Chinesischen Kaisers. Diese zeigen bei Austrocknung …
-
Low coherence speckle interferometry (LCSI) for the characterisation of adhesive bonded joints
Low Coherence Speckle Interferometry (LCSI) combines depth-resolved measurements of Low Coherence Interferometry and high-accuracy deformation measurements of Electronic Speckle Pattern Interferometry. Depth-resolved deformation measurements enable e.g. the characterisation of the behaviour of …
-
Residual Stress Development and Effect on the Piezoelectric Performance of Sol -Gel Derived Lead Zirconate Titanate (Pzt) Thin Films
Additionally two patterning methods, traditional chemical wet-etching and a novel soft lithographic technique, are explored as a means to reduce residual stress within film features. For the soft lithographic technique, film features are created by selective film cracking, a result of poor …
-
Behaviour of ultra high performance fibre reinforced concrete subjected to static and impact loads
… technique for the design, development and use of speckle patterns on the concrete surface of UHP-FRC beams for digital image correlation (DIC) measurements. The proposed method enables the creation of patterns with consistent speckle sizes and density in a simple, repeatable, rapid and inexpensive …
-
Full-field deformation measurement in wood using digital image processing
… technique consisted of creating a random speckle pattern on the specimen surface, recording images before deformation and after deformation, and computing the relative displacements of small image subsets. Two methods for producing speckle patterns on the specimens were studied: spray …
-
On-line evaluation of mode field distribution in optical fibers
… been found useful in fiberdyne measurements and speckle pattern analysis thus leading to information on the propagating modes. Chapters I and 2 give a brief introduction to fiber optic systems and mode theory while Chapter 3 reviews the work already done in that area. Chapter 4 describes the …
-
In-Situ Monitoring of Additive Manufacturing Using Digital Image Correlation
… a visual technique that compares the changes in speckle pattern in consecutive images of a specimen to determine the displacements and strains. This research aims to utilize the novel in-situ approach to investigate the processing-induced deformations due to variations in two process parameters: …
-
Characterization of laser noise in free-free beam structures using a Scanning Laser Doppler Vibrometer
… velocities is presented. An investigation of the speckle pattern motions which correspond to the areas prone to the laser noise and the effect of increased retroreflective surface treatments are explored. Additionally, the effect of three user defined parameters of the SLDV system are examined. In …
-
Laser Speckle Imaging: A Quantitative Tool for Flow Analysis
<p>Laser speckle imaging, often referred to as laser speckle contrast analysis (LASCA), has been sought after as a quasi-real-time, full-field, flow visualization method. It has been proven to be a valid and reliable qualitative method, but there has yet to be any definitive consensus on its …
-
An experimental and finite element analysis of the thermal deformation of an open sleeve piston
… of the holographic method and ESPI (electronic speckle pattern interferometry) for the measurement of piston deformation has also been carried out. In this part of the study, a simplified ESPI method was used for measuring two displacement components simultaneously using an out-of-plane …
-
Transport properties of a Bose-Einstein condensate with tunable interactions in the presence of a disordered or single defect potential
… BEC system using the light field from a laser speckle pattern. Using this system, we have investigated the effects of disorder or a single Gaussian defect, on the collective dipole motion of a BEC of 7Li in an optical trap. In addition, we perform transport experiments on a weakly interacting …
Page 1 of 2