Advances in the Study of Micromechanical Behaviour for Granular Materials Using Micro-CT Scanner and 3D Printing

This paper analyzes the pore morphology of two different concrete mixtures (plain and fiber-reinforced) under two different curing conditions, through the use of a CT scanner and post-processing software. Twelve cylinders of 45.2 mm in diameter and 50 mm in height were cast. Half of the specimens were kept in a humidity-controlled room, at 20 °C and 60% humidity, and the rest in a curing room, at 20 °C and 100% humidity. All the specimens were scanned at the age of 28 days, using a micro CT scanner. The results reveal that the presence of fibers substantially modifies the pore morphology in the way of increasing the volume of voids and the pore-size, reducing the shape factor of the voids and reorienting the voids toward a direction more aligned to the one showed by the fibers. In general, the curing conditions do no exhibit a great impact on the results.

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An Indirect Method to Measure Abutment Screw Preload: A Pilot Study Based on Micro-CT Scanning

Brazilian Dental Journal ◽

10.1590/0103-6440201300274 ◽

2015 ◽

Vol 26 (6) ◽

pp. 596-601 ◽

Cited By ~ 1

Author(s):

Carlos Eduardo E. Rezende ◽

Jason Alan Griggs ◽

Yuanyuan Duan ◽

Amanda M. Mushashe ◽

Gisele Maria Correr Nolasco ◽

...

Keyword(s):

Ct Scanning ◽

Measuring Method ◽

Micro Ct ◽

Ct Scanner ◽

Removal Torque ◽

Ct Technique ◽

Original Length ◽

Implant Abutment ◽

Torque Values ◽

Abutment Screw

This study aimed to measure the preload in different implant platform geometries based on micro-CT images. External hexagon (EH) implants and Morse Tapered (MT) implants (n=5) were used for the preload measurement. The abutment screws were scanned in micro-CT to obtain their virtual models, which were used to record their initial length. The abutments were screwed on the implant with a 20 Ncm torque and the set composed by implant, abutment screw and abutment were taken to the micro-CT scanner to obtain virtual slices of the specimens. These slices allowed the measurement of screw lengths after torque application and based on the screw elongation. Preload values were calculated using the Hooke's Law. The preloads of both groups were compared by independent t-test. Removal torque of each specimen was recorded. To evaluate the accuracy of the micro-CT technique, three rods with known lengths were scanned and the length of their virtual model was measured and compared with the original length. One rod was scanned four times to evaluate the measuring method variation. There was no difference between groups for preload (EH = 461.6 N and MT = 477.4 N), but the EH group showed higher removal torque values (13.8±4.7 against 8.2±3.6 Ncm for MT group). The micro-CT technique showed a variability of 0.053% and repeatability showed an error of 0.23 to 0.28%. Within the limitations of this study, there was no difference between external hexagon and Morse taper for preload. The method using micro-CT may be considered for preload calculation.

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Repeated Imaging of Lung Cancer Development Using PIXSCAN, a Low Dose Micro-CT Scanner Based on XPAD Hybrid Pixel Detectors

IEEE Transactions on Nuclear Science ◽

10.1109/tns.2009.2037319 ◽

2010 ◽

Vol 57 (1) ◽

pp. 242-245 ◽

Cited By ~ 2

Author(s):

Franck Debarbieux ◽

Alain Bonissent ◽

Patrick Breugnon ◽

Franca Cassol Brunner ◽

Pierre A. Delpierre ◽

...

Keyword(s):

Lung Cancer ◽

Low Dose ◽

Cancer Development ◽

Micro Ct ◽

Ct Scanner ◽

Pixel Detectors

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Error analysis of tomographic reconstructions in the absence of projection data

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2014.0394 ◽

2015 ◽

Vol 373 (2043) ◽

pp. 20140394 ◽

Cited By ~ 2

Author(s):

Snehlata Shakya ◽

Prabhat Munshi

Keyword(s):

Experimental Data ◽

Fourier Transform ◽

Error Estimates ◽

Projection Data ◽

Micro Ct ◽

Ct Scanner ◽

X Ray ◽

Level Data ◽

The Given ◽

Comparative Error

Error estimates for tomographic reconstructions (using Fourier transform-based algorithm) are available for cases where projection data are available. These data are used for reconstructions with different filter functions and the reliability of these reconstructions can be checked as per guidelines of those error estimates. There are cases where projection data are large (in gigabytes or terabytes) so storage of these data becomes an issue. It leads to storing of only the reconstructed images. Error estimation in such cases is presented here. Second-level projection data are calculated from the given reconstructed images (‘first-level’ images). These ‘second-level’ data are now used to generate ‘second-level’ reconstructed images. Different filter functions are employed to check the fidelity of these ‘second-level’ images. This inference is extended to first-level images in view of the characteristics of the convolution operator. This approach is validated with experimental data obtained by the X-ray micro-CT scanner installed at IIT Kanpur. Five specimens (of same material) have been scanned. Data are available in this case thus we have performed a comparative error estimate analysis for the ‘first-level’ reconstructions (data obtained from CT machine) and second-level reconstructions (data generated from first-level reconstructions). We observe that both approaches show similar outcome. It indicates that error estimates can also be applied to images when data are not available.

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