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DTA measurements have shown that on heating devitrification of Li2O – x(GeO2) glasses occurs in several stages. Phase composition of original, intermediate and final glass- ceramics states has been studied and identified by X-ray analysis. [ABSTRACT FROM AUTHOR]

Void growth and coalescence in a model material containing an artificial three-dimensional void array (the estimated local void volume fraction was 1.1%) were investigated by X-ray computed tomography (=XCT). The initially tapered cylindrical voids became elongated along the principal straining direction by some amount of tensile plastic deformation, and then the work-hardening capacity in the intervoid matrix was restored by an intermediate annealing. The annealed model material was pulled in tension all the way up to fracture to see if the existing void coalescence models can predict the void coalescence strain. [ABSTRACT FROM PUBLISHER]

Can the capabilities of the 'big three' synchrotron radiation facilities still be 'big' in the future? The three third-generation synchrotron radiation facilities - ESRF, APS, and SPring-8 - were inaugurated with performances significantly beyond that of smaller, lower-energy machines. For the past few years, though, mid-scale (∼3 GeV) low-emittance machines, both operating and planned, have been gaining ground, in part taking advantage of the technological developments at the larger rings. The future competitiveness of the big three was one of the issues addressed during the ESRF/APS/SPring-8 Three-Way Meeting. [ABSTRACT FROM AUTHOR]

The objective of this paper is to use the discrete element model (DEM) to predict the asphalt mixture dynamic modulus in the hollow cylindrical specimen across a range of test temperatures and load frequencies. The microstructure of the asphalt concrete specimen was captured by X-ray tomography techniques. The hollow circular images were produced from the layer of cylindrical X-ray computed tomography (X-ray CT) images. The asphalt concrete images were divided into three phases according to a density index: aggregate, sand mastic and air void phases. The sand mastic phase was composed of fine aggregates (smaller than 2.36 mm) and asphalt binder. The distribution of air void, sand mastic and aggregate were also investigated along with the depth of the hollow cylindrical specimen. In the DEM simulation, the sand mastic's dynamic modulus using different loading frequencies and test temperatures was used to predict the asphalt mixture's dynamic modulus. The predicted dynamic modulus was at that same loading frequency and test temperature with sand mastic's dynamic modulus. The strain response of the asphalt concrete under a tensile haversine load was calculated at the inner core of the hollow cylindrical specimen to determine the dynamic modulus. The linear contact-stiffness model and Burger's contact model were used to calculate this strain response. This paper has also investigated the difference in the dynamic modulus from the 2D and 3D models by comparing laboratory measurements of the asphalt mixture. When comparing the 2D and 3D DEM, the modulus prediction of the 3D DEM was around 27% higher than that of the 2D model. The difference in modulus between laboratory measurements and 3D DEM predictions was within a 10% range. The linear elastic model and the viscoelastic model were compared with the 2D DEM. When comparing these two models, it was found that the modulus difference was within a 5% range. [ABSTRACT FROM AUTHOR]

Wood density is an important quality variable, closely related to the mechanical properties of the wood. Precise wood density measurements in the log sorting would enable density sorting of logs for products such as strength-graded wood and finger-jointed wood. Density sorting of logs would also give more homogeneous drying properties and thus improve the quality of the final products. By compensating the radiographs from an X-ray log scanner for the varying path lengths using outer shape data from a three-dimensional (3D) scanner, it is possible to make precise estimates of both green and dry density. Measurements on simulated industrial data were compared with densities measured in computed tomographic (CT) images for 560 Scots pine (Pinus sylvestris L.) logs. It was found that green sapwood density could be measured with predictability R 2=0.65 and root mean square error (RMSE) of 25 kg m-3. Green and dry heartwood densities were measured with similar precision: R 2=0.79 and RMSE=32 kg m-3 for green density and R 2=0.83 and RMSE=32 kg m-3 for dry density. [ABSTRACT FROM AUTHOR]

Quality sorting of sawlogs based on three-dimensional (3D) or X-ray scanning or a multivariate combination of variables from both methods may be used to decrease the production of off-grade products carrying unwanted combinations of dimension and grade. There is, however, potential for further improving the sorting accuracy if 3D and X-ray raw data are combined at an early stage using path length compensation. From the measured 3D shape, a good estimate of the length of each X-ray path through the log can be made, enabling the calculation of a log density profile from the measured X-ray attenuation. The effect of this technique on heartwood diameter measurements of 423 Scots pine (Pinus sylvestris L.) logs was evaluated. By the addition of 3D data to the X-ray data it was possible to raise the predictability of the heartwood diameter from R 2=0.84 to 0.95 and to improve the root mean square error from 17 mm to 9.3 mm, primarily because of the enhanced contrast between heartwood and sapwood. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the individual board strength predictions from an X-ray log scanner by using either two or four X-ray directions. The benefit of applying traceability between log and board was also studied. In total, 119 Norway spruce [Picea abies (L.) Karst.] sawlogs were scanned by an X-ray log scanner at the log sorting station of a sawmill and sawn into two centre pieces per log. Individual board traceability was enabled by following the rotational position of the log in the scanner and at the succeeding sawing. All boards were graded by a commercial strength grading machine before destructive testing was done. The resulting data were used to derive variables for building multivariate partial least squares strength prediction models. In the modelling a hierarchical modelling approach was used, where annual ring width, dry density and elasticity were also modelled. For all concepts studied the models’ fit was similar. Only minor benefits could be found when using four directions and traceability compared with two directions and no traceability. One conclusion is that the result for traceability, from four directions in particular, is more sensitive for the interior knot reconstruction result. The strength prediction was on the same R2 level as for the strength grading machine. [ABSTRACT FROM AUTHOR]

The article focuses on a half-day workshop conducted by the Canadian Light Source, a research facility at the University of Saskatchewan in Saskatoon, Saskatchewan, to discuss various applications of tomography in the field of geology/paleontology, metallurgy, surface- and catalyst-chemistry and health sciences. Opening lecture of the workshop was given by Mark Rivers, co-director of the GSECARS sector at Advanced Photon Source. Rivers presented an overview of the advantages of X-rays and synchrotron radiation for imaging. Apostolos Kantzas of the University of Calgary, discussed the use of lab-based process tomography and micro-tomography for a variety of industrial applications including polymer-enhanced foams, polyethylene resins, phase separation, and pore space characterization in geological materials.