Search results for "Tomography"

Advances in microgeophysics for engineering and cultural heritage

2009

A large number of unconventional investigations have been implemented, tested, and validated in the field of microgeophysics, with the aim being to solve specific diagnostic and/or monitoring problems regarding civil engineering and cultural heritage studies. The investigations were carried out using different tomographic 2D and 3D approaches as well as different energy sources, namely sonic, ultrasonic and electromagnetic (radar) waves, electric potential fields, and infrared thermography. Many efforts have been made to modify instruments and procedures in order to improve the resolution of the surveys as well as to greatly reduce the time of the measurements without any loss of informatio…

Orthogonal switching of AMS axes during type-2 fold interference : Insights from integrated X-ray computed tomography, AMS and 3D petrography

2017

We applied X-ray computed microtomography (μ-CT) in combination with anisotropy of magnetic susceptibility (AMS) analysis to study metamorphic rock fabrics in an oriented drill core sample of pyrite-pyrrhotite-quartz-mica schist. The sample is extracted from the Paleoproterozoic Martimo metasedimentary belt of northern Finland. The μ-CT resolves the spatial distribution, shape and orientation of 25,920 pyrrhotite and 153 pyrite grains localized in mm-thick metapelitic laminae. Together with microstructural analysis, the μ-CT allows us to interpret the prolate symmetry of the AMS ellipsoid and its relationship to the deformation history. AMS of the sample is controlled by pyrrhotite porphyro…

Predicting stiffness and strength of birch pulp:Polylactic acid composites

2016

This paper studies failure of birch pulp–polylactic acid composites. Stiffness and strength are calculated using the theory of short fibre composites and the results are compared to experimental data. The results differed from the experimental values by 0–6%. With less aligned fibres the short fibre theory is not feasible. The performance of the 40 wt% birch pulp – polylactic acid composite is predicted with X-ray microtomography based finite element modelling, and the results are compared with experiments. Stiffness results differed from experiments by 1–17% . By adding into the models a third material phase representing the interface between the fibres and the matrix, the stress–strain c…

Calibration of the bone mineral density scale on X-ray microtomography

2016

Modelling the effect of porosity on the mechanical properties of unidirectional composites. The case of thick-walled pressure vessels

2018

International audience; The present article highlights morphological features present in composite pressure vessels. The use of X-ray microtomography provides three-dimensional information about the voids in a large thick-walled type 3 pressure vessel at the mesoscopic scale. The observations show that the porosity structure depends strongly on composite thickness and orientation. A numerical approach is proposed to model realistically the damage phenomena in pressure vessels.

Influence of B content on microstructure, phase composition and mechanical properties of CVD Ti(B,N) coatings

2022

Within this work the effect of the B content on the microstructure, phase composition and mechanical properties of CVD Ti(B,N) coatings is investigated. Ti(B,N) coatings with B contents from 0 (fcc-TiN) to ∼5, ∼15, ∼30, ∼45 and 66 (h-TiB2) at.% have been deposited by CVD. The elemental composition of the coatings was confirmed by ERDA and their microstructure was investigated using XRD and SEM. With increasing B content, a transition from a fcc to a h-dominated structure via dual-phase fcc/h-Ti(B,N) was observed, which was accompanied by a decreasing grain size from the µm to nm range. Combinatorial use of Raman spectroscopy, XPS and APT measurements indicated B-rich grain boundary segregat…

Performance Enhancement of a Small Animal Positron Emission Tomograph based on Continuous Crystals and Silicon Photomultipliers

2017

La tomografía por emisión de positrones (PET, por sus siglas en inglés) es una técnica de Medicina Nuclear que permite obtener de manera no invasiva imágenes funcionales “in vivo” marcando un compuesto orgánico con un emisor de positrones. Los tomógrafos PET requieren un alta resolución espacial y sensibilidad para estimar con precisión la distribución del radiotrazador en el animal. Frente a los bloques pixelados comúnmente utilizados en PET, los detectores que consisten en la combinación de cristales continuos acoplados a fotodetectores segmentados pueden ofrecer una mayor eficiencia y una alta resolución espacial. Esta última depende de la precisión de los algoritmos de determinación de …

Usefulness of multiplanar reconstruction with multislice computed tomography to assess hepatocellular carcinoma response after transcatheter arterial…

2008

Assessment of the tibia using ultrasonic guided waves in pubertal girls

2002

The purpose of this study was to compare low frequency ultrasonic guided wave measurements with established ultrasound and bone density measurements in terms of their ability to characterize the tibia in pubertal girls. Subjects were 12-14-year-old girls ( n=106) who were participating in a calcium and vitamin D intervention study. A prototype low frequency pulse transmission device consisting of a uniaxial scanning mechanism and low frequency transducers orientated perpendicularly to the limb was used to measure two ultrasound velocities in the tibia. The first velocity, V1, was that of the first arriving signal, similar to that measured by existing commercial tibial ultrasound devices. Th…

Detection of bifid mandibular condyle using computed tomography

2011

Objective: To determine the frequency and characteristics of bifid mandibular condyle (BMC) using computed tomography (CT) evaluation. Study Design: A retrospective study was carried out using the CT records of 550 patients referred to the Medical School of Erciyes University (Kayseri, Turkey) between 2007 and 2010. T-tests were used to compare frequency of BMC between the left and right sides and between female and male patients. Statistical analysis was performed using SPSS software and a chi-squared test. Results: Of the 550 Patients, 10 patients (1.82%) were found to have BMCs. Five patients were female (50%) and five were male (50%). Of these 10 patients, 7 (70%) had unilateral and 3 (…