scholarly journals Assessment of Geometrical and Transport Properties of a Fibrous C/C Composite Preform Using x-ray Computerized Micro-tomography: Part I. Image Acquisition and Geometrical Properties

2005 ◽  
Vol 20 (9) ◽  
pp. 2328-2339 ◽  
Author(s):  
Olivia Coindreau ◽  
Gérard L. Vignoles
Keyword(s):  
Pore Space ◽  
Three Dimensional ◽  
Internal Surface ◽  
Carbon Composite ◽  
Internal Surface Area ◽  
X Ray ◽  
Geometrical Properties ◽  
Original Algorithm ◽  
Micro Tomography

Raw and partially infiltrated carbon–carbon composite preforms have been scanned by high-resolution synchrotron radiation x-ray computerized micro-tomography. Three dimensional high-quality images of the pore space have been produced at two distinct resolutions and have been used for the computation of geometrical quantities: porosity, internal surface area, pore sizes, and their distributions, as well as local and average fiber directions. Determination of the latter property makes use of an original algorithm. All quantities have been compared to experimental data with good results. Structural models appropriate for ideal families of cylinders are shown to represent adequately the actual pore space.

scholarly journals Assessment of geometrical and transport properties of a fibrous C/C composite preform as digitized by x-ray computerized microtomography: Part II. Heat and gas transport properties

2007 ◽  
Vol 22 (6) ◽  
pp. 1537-1550 ◽  
Author(s):  
Gerard L. Vignoles ◽  
Olivia Coindreau ◽  
Azita Ahmadi ◽  
Dominique Bernard
Keyword(s):  
Transport Properties ◽  
Pore Space ◽  
Three Dimensional ◽  
Carbon Composite ◽  
X Ray ◽  
Gas Transport Properties ◽  
Change Of Scale ◽  
Local Determination ◽  
Good Agreement

Raw and partially infiltrated carbon–carbon composite preforms have been scanned by high-resolution synchrotron radiation x-ray computerized microtomography. Three-dimensional high-quality images of the pore space have been produced at two distinct resolutions and have been used for the computation of transport properties: heat conductivity, binary gas diffusivities, Knudsen diffusivities, and viscous flow permeabilities. The computation procedures are based on a double change-of-scale strategy suited to the bimodal nature of pore space and on the local determination of transport anisotropy. Good agreement has been found between all calculated quantities and experimental data.

scholarly journals Pore formation during dehydration of a polycrystalline gypsum sample observed and quantified in a time-series synchrotron X-ray micro-tomography experiment

Solid Earth ◽  
2012 ◽  
Vol 3 (1) ◽  
pp. 71-86 ◽  
Author(s):  
F. Fusseis ◽  
C. Schrank ◽  
J. Liu ◽  
A. Karrech ◽  
S. Llana-Fúnez ◽  
...  
Keyword(s):  
Time Series ◽  
Pore Space ◽  
Three Dimensional ◽  
Internal Stresses ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Computer Codes ◽  
Micro Tomography ◽  
Effective Drainage

Abstract. We conducted an in-situ X-ray micro-computed tomography heating experiment at the Advanced Photon Source (USA) to dehydrate an unconfined 2.3 mm diameter cylinder of Volterra Gypsum. We used a purpose-built X-ray transparent furnace to heat the sample to 388 K for a total of 310 min to acquire a three-dimensional time-series tomography dataset comprising nine time steps. The voxel size of 2.2 μm3 proved sufficient to pinpoint reaction initiation and the organization of drainage architecture in space and time. We observed that dehydration commences across a narrow front, which propagates from the margins to the centre of the sample in more than four hours. The advance of this front can be fitted with a square-root function, implying that the initiation of the reaction in the sample can be described as a diffusion process. Novel parallelized computer codes allow quantifying the geometry of the porosity and the drainage architecture from the very large tomographic datasets (20483 voxels) in unprecedented detail. We determined position, volume, shape and orientation of each resolvable pore and tracked these properties over the duration of the experiment. We found that the pore-size distribution follows a power law. Pores tend to be anisotropic but rarely crack-shaped and have a preferred orientation, likely controlled by a pre-existing fabric in the sample. With on-going dehydration, pores coalesce into a single interconnected pore cluster that is connected to the surface of the sample cylinder and provides an effective drainage pathway. Our observations can be summarized in a model in which gypsum is stabilized by thermal expansion stresses and locally increased pore fluid pressures until the dehydration front approaches to within about 100 μm. Then, the internal stresses are released and dehydration happens efficiently, resulting in new pore space. Pressure release, the production of pores and the advance of the front are coupled in a feedback loop.

scholarly journals Pore formation during dehydration of polycrystalline gypsum observed and quantified in a time-series synchrotron radiation based X-ray micro-tomography experiment

2011 ◽  
Vol 3 (2) ◽  
pp. 857-900 ◽  
Author(s):  
F. Fusseis ◽  
C. Schrank ◽  
J. Liu ◽  
A. Karrech ◽  
S. Llana-Fúnez ◽  
...  
Keyword(s):  
Time Series ◽  
Pore Space ◽  
Three Dimensional ◽  
Internal Stresses ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Computer Codes ◽  
Micro Tomography ◽  
Effective Drainage

Abstract. We conducted an in-situ X-ray micro-computed tomography heating experiment at the Advanced Photon Source (USA) to dehydrate an unconfined 2.3 mm diameter cylinder of Volterra Gypsum. We used a purpose-built X-ray transparent furnace to heat the sample to 388 K for a total of 310 min to acquire a three-dimensional time-series tomography dataset comprising nine time steps. The voxel size of 2.2 μm3 proved sufficient to pinpoint reaction initiation and the organization of drainage architecture in space and time. We observed that dehydration commences across a narrow front, which propagates from the margins to the centre of the sample in more than four hours. The advance of this front can be fitted with a square-root function, implying that the initiation of the reaction in the sample can be described as a diffusion process. Novel parallelized computer codes allow quantifying the geometry of the porosity and the drainage architecture from the very large tomographic datasets (6.4 × 109 voxel each) in unprecedented detail. We determined position, volume, shape and orientation of each resolvable pore and tracked these properties over the duration of the experiment. We found that the pore-size distribution follows a power law. Pores tend to be anisotropic but rarely crack-shaped and have a preferred orientation, likely controlled by a pre-existing fabric in the sample. With on-going dehydration, pores coalesce into a single interconnected pore cluster that is connected to the surface of the sample cylinder and provides an effective drainage pathway. Our observations can be summarized in a model in which gypsum is stabilized by thermal expansion stresses and locally increased pore fluid pressures until the dehydration front approaches to within about 100 μm. Then, the internal stresses are released and dehydration happens efficiently, resulting in new pore space. Pressure release, the production of pores and the advance of the front are coupled in a feedback loop. We discuss our findings in the context of previous studies.

Modelling Infiltration of Fibre Preforms From X-Ray Tomography Data

2010 ◽  
Vol 71 ◽  
pp. 108-117 ◽  
Author(s):  
Gerard L. Vignoles ◽  
William Ros ◽  
Ivan Szelengowicz ◽  
Christianne Mulat ◽  
Christian Germain ◽  
...  
Keyword(s):  
Large Scale ◽  
Pore Space ◽  
Chemical Vapour ◽  
Ceramic Matrix Composites ◽  
Internal Surface ◽  
High Tech ◽  
Small Scale ◽  
Internal Surface Area ◽  
X Ray ◽  
Matrix Deposition

The production of high-quality Ceramic-Matrix Composites often includes matrix deposition by Chemical Vapour Infiltration (CVI), a process which involves many phenomena such as gas transport, chemical reactions, and structural evolution of the preform. Control and optimization of this high-tech process are demanding for modelling tools. In this context, a numerical simulation of CVI in complex 3D images, acquired e.g. by X-ray Computerized Microtomography, has been developed. The approach addresses the two length scales which are inherent to a composite with woven textile reinforcement (i.e. inter- and intra-bundle), with two numerical tools. The small-scale program allows direct simulation of CVI in small intra-bundle pores. Effective laws for porosity, internal surface area and transport properties as infiltration proceeds are produced by averaging. They are an input for the next modelling step. The second code is a large-scale solver which accounts for the locally heterogeneous and anisotropic character of the pore space. Simulation of the infiltration of a whole composite material part is possible with this program. Validation of these tools on test cases, as well as some examples on actual materials, are shown and discussed.

scholarly journals Square-wave voltammetric determination of rutin in pharmaceutical formulations using a carbon composite electrode modified with copper (II) phosphate immobilized in polyester resin

2012 ◽  
Vol 48 (4) ◽  
pp. 639-649 ◽  
Author(s):  
Kellen Heloizy Garcia Freitas ◽  
Orlando Fatibello-Filho ◽  
Ivanildo Luiz de Mattos
Keyword(s):  
Modified Electrode ◽  
Composite Electrode ◽  
Polyester Resin ◽  
Pharmaceutical Formulations ◽  
Carbon Composite ◽  
X Ray ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Carbon Composite Electrode

A carbon composite electrode modified with copper (II) phosphate immobilized in a polyester resin (Cu3(PO4)2-Poly) for the determination of rutin in pharmaceutical samples by square-wave voltammetry is described herein. The modified electrode allows the determination of rutin at a potential (0.20 V vs. Ag/AgCl (3.0 mol L-1 KCl)) lower than that observed at an unmodified electrode. The peak current was found to be linear to the rutin concentration in the range from 9.9 × 10-8 to 2.5 × 10-6 mol L-1, with a detection limit of 1.2×10-8 mol L-1. The response of the electrode was stable, with no variation in baseline levels within several hours of continuous operation. The surface morphology of the modified electrode was characterized by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) system. The results obtained are precise and accurate. In addition, these results are in agreement with those obtained by the chromatographic method at a 95% confidence level.

scholarly journals Investigating the Three-Dimensional Microstructural Characteristics of Lithium-Sulfur Electrodes with X-ray Micro-Tomography

2017 ◽  
Vol 77 (11) ◽  
pp. 447-455 ◽  
Author(s):  
Chun Tan ◽  
Sohrab Randjbar Daemi ◽  
Daniel J.L. Brett ◽  
Paul R. Shearing
Keyword(s):  
Three Dimensional ◽  
Microstructural Characteristics ◽  
X Ray ◽  
Micro Tomography ◽  
Lithium Sulfur

scholarly journals Determination of the Three-dimensional Structure of Dislocations by Synchrotron White X-ray Topography Combined with a Topo-tomographic Technique

Materia Japan ◽  
2007 ◽  
Vol 46 (12) ◽  
pp. 823-823
Author(s):  
Seiji Kawado ◽  
Toshinori Taishi ◽  
Satoshi Iida ◽  
Yoshifumi Suzuki ◽  
Yoshinori Chikaura ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
X Ray ◽  
Three Dimensional Structure ◽  
Tomographic Technique

scholarly journals Synchrotron radiation X-ray tomographic microscopy (SRXTM) of brachiopod shell interiors for taxonomy: Preliminary report

2010 ◽  
pp. 109-117 ◽  
Author(s):  
Neda Motchurova-Dekova ◽  
David Harper
Keyword(s):  
Synchrotron Radiation ◽  
Three Dimensional ◽  
X Rays ◽  
X Ray ◽  
Fine Grained ◽  
Internal Structures ◽  
Efficient Alternative ◽  
Micro Tomography ◽  
Light Beams ◽  
Non Destructive

Synchrotron radiation X-ray tomographic microscopy (SRXTM) is a non-destructive technique for the investigation and visualization of the internal features of solid opaque objects, which allows reconstruction of a complete three-dimensional image of internal structures by recording of the differences in the effects on the passage of waves of energy reacting with those structures. Contrary to X-rays, produced in a conventional X-ray tube, the intense synchrotron light beams are sharply focused like a laser beam. We report encouraging results from the use of SRXTM for purely taxonomic purposes in brachiopods: an attempt to find a non-destructive and more efficient alternative to serial sectioning and several other methods of dissection together with the non-destructive method of X-ray computerised micro-tomography. Two brachiopod samples were investigated using SRXTM. In ?Rhynchonella? flustracea it was possible to visualise the 3D shape of the crura and dental plates. In Terebratulina imbricata it was possible to reveal the form of the brachidium. It is encouraging that we have obtained such promising results using SRXTM with our very first two fortuitous samples, which had respectively fine-grained limestone and marl as infilling sediment, in contrast to the discouraging results communicated to us by some colleagues who have tested specimens with such infillings using X-ray micro-tomography. In future the holotypes, rare museum specimens or delicate Recent material may be preferentially subjected to this mode of analysis.

X-ray topographic determination of the granular structure in a graphite mosaic crystal: a three-dimensional reconstruction

2000 ◽  
Vol 33 (4) ◽  
pp. 1023-1030 ◽  
Author(s):  
M. Ohler ◽  
M. Sanchez del Rio ◽  
A. Tuffanelli ◽  
M. Gambaccini ◽  
A. Taibi ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Pyrolytic Graphite ◽  
Three Dimensional ◽  
X Ray ◽  
Dimensional Reconstruction ◽  
Mosaic Crystals ◽  
Spatial Locations ◽  
Crystalline Domains

Section topographs recorded at different spatial locations and at different rocking angles of a highly oriented pyrolytic graphite (HOPG) crystal allow three-dimensional maps of the local angular-dependent scattering power to be obtained. This is performed with a direct reconstruction from the intensity distribution on such topographs. The maps allow the extraction of information on local structural parameters such as size, form and internal mosaic spread of crystalline domains. This data analysis leads to a new method for the characterization of mosaic crystals. Perspectives and limits of applicability of this method are discussed.

Determination of the Workspace of 6-DOF Parallel Manipulators

1989 ◽  
Author(s):  
C. Gosselin
Keyword(s):  
Parallel Manipulator ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Geometrical Properties ◽  
Cartesian Space ◽  
Six Degree Of Freedom

Abstract This paper presents an algorithm for the determination of the workspace of parallel manipulators. The method described here, which is based on geometrical properties of the workspace, leads to a simple graphical representation of the regions of the three-dimensional Cartesian space that are attainable by the manipulator with a given orientation of the platform. Moreover, the volume of the workspace can be easily computed by performing an integration on its boundary, which is obtained from the algorithm. Examples are included to illustrate the application of the method to a six-degree-of-freedom fully-parallel manipulator.

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