scholarly journals Ten-Year Monitoring of the Grandes Jorasses Glaciers Kinematics. Limits, Potentialities, and Possible Applications of Different Monitoring Systems

2021 ◽  
Vol 13 (15) ◽  
pp. 3005
Author(s):  
Niccolò Dematteis ◽  
Daniele Giordan ◽  
Fabrizio Troilo ◽  
Aleksandra Wrzesniak ◽  
Danilo Godone
Keyword(s):  
Complex Geometry ◽  
Specific Area ◽  
Cost Effective ◽  
Time Lapse ◽  
Image Correlation ◽  
Gnss Receivers ◽  
Potential Failure ◽  
Nw Italy ◽  
Integration Strategies ◽  
Data Continuity

In the Ferret Valley (NW Italy), anthropic activities coexist close to the Grandes Jorasses massif’s glaciological complex. In the past, break-off events have caused damage to people and infrastructure. These events concerned two specific sectors: the Montitaz Lobe (Planpincieux Glacier) and the Whymper Serac (Grandes Jorasses Glacier). Since 2010, permanent and discontinuous survey campaigns have been conducted to identify potential failure precursors, investigate the glacier instability processes, and explore different monitoring approaches. Most of the existing terrestrial apparatuses that measure the surface kinematics have been adopted in the Grandes Jorasses area. The monitoring sites in this specific area are characterized by severe weather, complex geometry, logistic difficulties, and rapid processes dynamics. Such exceptional conditions highlighted the limitations and potentialities of the adopted monitoring approaches, including robotic total station (RTS), GNSS receivers, digital image correlation applied to time-lapse imagery, and terrestrial radar interferometry (TRI). We examined the measurement uncertainty of each system and their monitoring performances. We discussed their principal limitations and possible use for warning purposes. In the Grandes Jorasses area, the use of a time-lapse camera appeared to be a versatile and cost-effective solution, which, however is not suitable for warning applications, as it does not guarantee data continuity. RTS and GNSS have warning potentialities, but the target installation and maintenance in remote environments remain challenging. TRI is the most effective monitoring system for early warning purposes in such harsh conditions, as it provides near-real-time measurements. However, radar equipment is very costly and requires extreme logistic effort. In this framework, we present data integration strategies to overcome the abovementioned limits and we demonstrate that these strategies are optimal solutions to obtain data continuity and robustness.

scholarly journals Sensor Integrated Load-Bearing Structures: Measuring Axis Extension with DIC-Based Transducers

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4104
Author(s):  
Nassr Al-Baradoni ◽  
Peter Groche
Keyword(s):  
Cost Effective ◽  
Image Correlation ◽  
Maximum Deviation ◽  
Single Image ◽  
Eccentric Load ◽  
Load Bearing ◽  
Out Of Plane ◽  
Axis Extension ◽  
Plane Displacement ◽  
Imaging Sensor

In this paper we present a novel, cost-effective camera-based multi-axis force/torque sensor concept for integration into metallic load-bearing structures. A two-part pattern consisting of a directly incident and mirrored light beam is projected onto the imaging sensor surface. This allows the capturing of 3D displacements, occurring due to structure deformation under load in a single image. The displacement of defined features in size and position can be accurately analyzed and determined through digital image correlation (DIC). Validation on a prototype shows good accuracy of the measurement and a unique identification of all in- and out-of-plane displacement components under multiaxial load. Measurements show a maximum deviation related to the maximum measured values between 2.5% and 4.8% for uniaxial loads ( and between 2.5% and 10.43% for combined bending, torsion and axial load. In the course of the investigations, the measurement inaccuracy was partly attributed to the joint used between the sensor parts and the structure as well as to eccentric load.

scholarly journals A study of the progression of damage in an axially loaded Branta leucopsis femur using X-ray computed tomography and digital image correlation

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3416 ◽  
Author(s):  
Zartasha Mustansar ◽  
Samuel A. McDonald ◽  
William Irvin Sellers ◽  
Phillip Lars Manning ◽  
Tristan Lowe ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Time Lapse ◽  
Image Correlation ◽  
Long Bone ◽  
Barnacle Goose ◽  
3D Images ◽  
X Ray ◽  
X Ray Computed

This paper uses X-ray computed tomography to track the mechanical response of a vertebrate (Barnacle goose) long bone subjected to an axial compressive load, which is increased gradually until failure. A loading rig was mounted in an X-ray computed tomography system so that a time-lapse sequence of three-dimensional (3D) images of the bone’s internal (cancellous or trabecular) structure could be recorded during loading. Five distinct types of deformation mechanism were observed in the cancellous part of the bone. These were (i) cracking, (ii) thinning (iii) tearing of cell walls and struts, (iv) notch formation, (v) necking and (vi) buckling. The results highlight that bone experiences brittle (notch formation and cracking), ductile (thinning, tearing and necking) and elastic (buckling) modes of deformation. Progressive deformation, leading to cracking was studied in detail using digital image correlation. The resulting strain maps were consistent with mechanisms occurring at a finer-length scale. This paper is the first to capture time-lapse 3D images of a whole long bone subject to loading until failure. The results serve as a unique reference for researchers interested in how bone responds to loading. For those using computer modelling, the study not only provides qualitative information for verification and validation of their simulations but also highlights that constitutive models for bone need to take into account a number of different deformation mechanisms.

Cost-effective Time Lapse Seismic Based on Direct Transmitted P-waves for Monitoring Sagd Heavy Oil Production

2018 ◽  
Author(s):  
M. Gareev ◽  
M. Amerkhanov ◽  
M. Lyabipov ◽  
A. Stepanov ◽  
R. Sitdikov ◽  
...  
Keyword(s):  
Heavy Oil ◽  
Oil Production ◽  
Cost Effective ◽  
Time Lapse ◽  
P Waves ◽  
Effective Time

Preliminary Results on the Performance of Cost-effective GNSS Receivers for RTK

2019 ◽  
Author(s):  
Somnath Mahato ◽  
Atanu Santra ◽  
Sukabya Dan ◽  
Partha Rakshit ◽  
P Banerjee ◽  
...  
Keyword(s):  
Cost Effective ◽  
Preliminary Results ◽  
Gnss Receivers

scholarly journals The effect of processing parameters on the mechanical characteristics of PLA produced by a 3D FFF printer

2020 ◽  
Vol 111 (3-4) ◽  
pp. 695-709
Author(s):  
H. Gonabadi ◽  
A. Yadav ◽  
S. J. Bull
Keyword(s):  
Tensile Strength ◽  
Young’S Modulus ◽  
Process Parameters ◽  
Mechanical Response ◽  
Complex Geometry ◽  
Young's Modulus ◽  
Laminate Plate ◽  
Surface Strain ◽  
Image Correlation ◽  
Build Orientation

Abstract 3D printing by fused filament fabrication (FFF) provides an innovative manufacturing method for complex geometry components. Since FFF is a layered manufacturing process, effects of process parameters are of concern when plastic materials such as polylactic acid (PLA), polystyrene and nylon are used. This study explores how the process parameters, e.g. build orientation and infill pattern/density, affect the mechanical response of PLA samples produced using FFF. Digital image correlation (DIC) was employed to get full-field surface-strain measurements. The results show the influence of build orientation and infill density is significant. For on-edge orientation, the tensile strength and Young’s modulus were 55 MPa and 3.5 GPa respectively, which were about 91% and 40% less for the upright orientation, demonstrating a significant anisotropy. The tensile strength and Young’s modulus increased with increasing infill density. In contrast, different infill patterns have no significant effect. Considering the influence of build orientation, based on the experimental results, a constitutive model derived from the laminate plate theory was employed. The material parameters were determined by tensile tests. Results demonstrated a reasonable agreement between the experimental data and the predictive model. Similar anisotropy to tension was observed in shear tests; shear modulus and shear strength for 45° flat orientation were about 1.55 GPa and 36 MPa, whereas for upright specimens they were about 0.95 GPa and 18 MPa, respectively. The findings provide a framework for systematic mechanical characterisation of 3D-printed polymers and potential ways of choosing process parameters to maximise performance for a given design.

scholarly journals A Cost-Effective Method to Reproduce the Morphology of the Nearshore and Intertidal Zone in Microtidal Environments

2020 ◽  
Vol 12 (11) ◽  
pp. 1880
Author(s):  
Stefano Furlani ◽  
Valeria Vaccher ◽  
Vanja Macovaz ◽  
Stefano Devoto
Keyword(s):  
Intertidal Zone ◽  
Field Tests ◽  
Cost Effective ◽  
Time Lapse ◽  
3D Models ◽  
The North ◽  
Cost Effective Method ◽  
Photogrammetric Method ◽  
The Difference ◽  
Sea Wall

The photogrammetric method is widely used in coastal areas and in submerged environments. Time-lapse images collected with unmanned aerial vehicles are used to reproduce the emerged areas, while images taken by divers are used to reproduce submerged ones. Conversely, 3D models of natural or human-made objects lying at the water level are severely affected by the difference in refractive index between air and seawater. For this reason, the matching of 3D models of emergent and submerged coasts has been very rarely tested and never used in Earth Sciences. The availability of a large number of time-lapse images, collected at the intertidal zone during previous snorkel surveys, encouraged us to test the merging of 3D models of emerged and submerged environments. Considering the rapid and effective nature of the aforementioned program of swim surveys, photogrammetric targets were not used during image acquisition. This forced us to test the matching of the independent models by recognizing prominent landforms along the waterline. Here we present the approach used to test the method, the instrumentation used for the field tests, and the setting of cameras fixed to a specially built aluminum support console and discuss both its advantages and its limits compared to UAVs. 3D models of sea cliffs were generated by applying structure-from-motion (SfM) photogrammetry. Horizontal time-lapse images, collected with action cameras while swimming parallel to the coastline at nearly constant velocity, were used for the tests. Subsequently, prominent coastal landforms were used to couple the independent models obtained from the emergent and submerged cliffs. The method was pilot tested in two coastal sites in the north-eastern Adriatic (part of the Mediterranean basin). The first site was a 25 m sea wall of sandstone set within a small harbor, while the second site was a 150 m route below plunging limestone cliffs. The data show that inexpensive action cameras provide a sufficient resolution to support and integrate geomorphological field surveys along rocky coastlines.

scholarly journals Image georectification and feature tracking toolbox: ImGRAFT

2015 ◽  
Vol 4 (1) ◽  
pp. 23-34 ◽  
Author(s):  
A. Messerli ◽  
A. Grinsted
Keyword(s):  
Feature Tracking ◽  
Cost Effective ◽  
Time Lapse ◽  
Post Processing ◽  
Outlet Glacier ◽  
Use Of Time ◽  
Camera Systems ◽  
Wide Range ◽  
Oblique Images ◽  
Minimal Effort

Abstract. The use of time-lapse camera systems is becoming an increasingly popular method for data acquisition. The camera setup is often cost-effective and simple, allowing for a large amount of data to be accumulated over a variety of environments for relatively minimal effort. The acquired data can, with the correct post-processing, result in a wide range of useful quantitative and qualitative information in remote and dangerous areas. The post-processing requires a significant amount of steps to transform images into meaningful data for quantitative analysis, such as velocity fields. To the best of our knowledge at present a complete, openly available package that encompasses georeferencing, georectification and feature tracking of terrestrial, oblique images is still absent. This study presents a complete, yet adaptable, open-source package developed in MATLAB, that addresses and combines each of these post-processing steps into one complete suite in the form of an "Image GeoRectification and Feature Tracking" (ImGRAFT: http://imgraft.glaciology.net) toolbox. The toolbox can also independently produce other useful outputs, such as viewsheds, georectified and orthorectified images. ImGRAFT is primarily focused on terrestrial oblique images, for which there are currently limited post-processing options available. In this study, we illustrate ImGRAFT for glaciological applications on a small outlet glacier Engabreen, Norway.

Analysis Accuracy of Digital Image Correlation Technique to Monitor Natural Frequency Response of Building under Dynamic Excitation

2011 ◽  
Vol 71-78 ◽  
pp. 3904-3908
Author(s):  
Ming Hsiang Shih ◽  
Wen Pei Sung ◽  
Feng Jen Tsai
Keyword(s):  
Digital Image Correlation ◽  
Frequency Response ◽  
Natural Frequency ◽  
Digital Image ◽  
Correlation Method ◽  
Cost Effective ◽  
Image Correlation ◽  
Correlation Technique ◽  
The People ◽  
External Forces

Strong typhoon and earthquake seriously threaten the safety of the life and property of the people. A cost-effective and reliable method is proposed to monitor the natural frequency response of building under excitation of external forces based on the applying digital image correlation method, DIC. The analysis accuracy of this dynamic DIC method is tested and verified by comparing with numerical analysis program, accelerometers, ACC and fast Fourier Transform, FFT. The test results reveal that the analysis accuracy of this DIC method near to the ACC and FFT traditional experimental methods. They demonstrate that using this DIC method to detect dynamic response of building under the excitation of external force has high practicability.

scholarly journals Sequential-Digital Image Correlation for Mapping Human Posterior Sclera and Optic Nerve Head Deformation

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Jeffrey D. Pyne ◽  
Katia Genovese ◽  
Luciana Casaletto ◽  
Jonathan P. Vande Geest
Keyword(s):  
Optic Nerve ◽  
Digital Image Correlation ◽  
Optic Nerve Head ◽  
Digital Image ◽  
Complex Geometry ◽  
Open Angle Glaucoma ◽  
Image Correlation ◽  
Optical Methods ◽  
Retinal Ganglion ◽  
Position Measurement

Optic nerve head (ONH) deformations may be involved in the onset or further development of glaucoma, including in patients with relatively normal intraocular pressures (IOPs). Characterizing posterior scleral deformations over physiological pressures may provide a better understanding of how changes in IOP lead to changes in the mechanical environment of the ONH and possibly retinal ganglion cell death. Pressure inflation measurement test protocols are commonly used to measure deformation of the peripapillary sclera with full-field noncontact optical methods. The purpose of this work was to develop and validate a new sequential 3D digital image correlation (S-DIC) approach for quantification of posterior scleral pressure induced deformation that improves z (in-depth) resolution of the DIC measurement without losing in-plane sensitivity, while also being able to contour and map deformations of the complex-shaped ONH. Our approach combines two orthogonal axes of parallax with standard 3D DIC methods using a single high-resolution camera. The enhanced capabilities of S-DIC with respect to standard 3D DIC has been demonstrated by carrying out a complete benchmark for shape, deformation, and strain measurement on an object of known complex geometry. Our S-DIC method provided a reconstruction accuracy of 0.17% and an uncertainty in z-position measurement of 8 μm. The developed methodology has also been applied to a human posterior scleral shell, including the full peripapillary sclera and optic nerve. The relatively inexpensive S-DIC approach may provide new information on the biomechanical deformations of the optic nerve head and, thus, the death of retinal ganglion cells in primary open angle glaucoma.

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