The Final Gravettian level (level 2) of the abri Pataud (Dordogne, France) yielded a large assemb... more The Final Gravettian level (level 2) of the abri Pataud (Dordogne, France) yielded a large assemblage of body ornaments that consists essentially of 85 quite standardized rectangular beads. Some uncertainty remained about the raw material in which these small beads were made: mammoth ivory, reindeer antler or bone? Non-invasive methods were employed in order to determine the raw material. First chemical analyses using microbeam Proton Induced X-ray Emission analysis (microPIXE) did not enable us to conclude definitively. Therefore, synchrotron and laboratory X-ray microtomography (microCT) were applied on eight beads and allowed us to identify ivory for all of them except for one, which shows slightly different morphological features. Due to their association with the human remains of level 2, these rectangular beads could be considered, like other “extraordinary” objects, as mortuary deposits. In this level, bones and reindeer antler are very abundant whereas mammoth ivory is rare:...
Le niveau 2 du site de l’abri Pataud (Les Eyzies-de-Tayac, Dordogne), daté du Gravettien final (-... more Le niveau 2 du site de l’abri Pataud (Les Eyzies-de-Tayac, Dordogne), daté du Gravettien final (-22 000 BP) a livré un nombre important d’éléments de parure dont l’essentiel correspond à 85 perles rectangulaires assez standardisées. Ces pièces étant de très petites dimensions (6 à 10 mm de longueur) et fortement polies, certaines incertitudes demeuraient quant à la matière première employée pour leur réalisation : os, bois de renne ou ivoire de mammouth ? Afin de déterminer la nature des matières dures d’origine animale utilisées, des méthodes d’examen non-invasives ont été employées sur des perles, sur des matériaux actuels et paléolithiques provenant du même niveau archéologique. L’analyse par émission des rayons X (PIXE) permettant une analyse non-invasive de la composition chimique au niveau des éléments majeurs, mineurs et traces, et la microtomographie X (microCT) permettant un examen micromorphologique non-destructif, ont été réalisées respectivement à l’aide de l’accélérateu...
We present, for the first time, Doppler-maps of the asynchronous polars BY Camelopardalis and V14... more We present, for the first time, Doppler-maps of the asynchronous polars BY Camelopardalis and V1432 Aquilae. BY Cam and V1432 Aql belong to a four member subclass of asynchronous polars, where orbital and spin period of the white dwarf differ by ~ 1 %. Contrary to their synchronized relatives, the ballistic accretion stream encounters a changing orientation of the magnetic-field during a beat cycle. As a consequence, infalling matter should be threaded onto different field lines, and directed to the energetically favoured pole. We obtained sets of high resolution (≈ 0.7Å ), phase-resolved (Deltaphi ≈ 0.01) spectra of both systems at the 3.5 m telescope at Calar Alto with the TWIN spectrograph. The resulting Doppler-maps for both stars show no clear signatures of the ballistic and/or magnetic accretion stream frequently detected in tomograms of synchronized systems. Instead the emission is spread over a wide range of velocities. This is most probably an indication of matter not accreted in a single stream, but via a curtain extending over a wide range in azimuth. We also find evidence for the heated side of the secondary star for BY Cam, from which the Doppler-maps could be phased.
Precautions in the generation of surfaces from CT images should be the rule. Two different data s... more Precautions in the generation of surfaces from CT images should be the rule. Two different data sets of the bust of Nefertiti and addi tional data from an industrial CT scanner will show the conflicts that arise when defining a surface. The recent trend in CT is to extract surfaces from CT measurements which can compete with the accuracy of
Due to the progress in Computed Tomography (CT) applied for dimensional control new fields in ma-... more Due to the progress in Computed Tomography (CT) applied for dimensional control new fields in ma-terials characterization are opened. Especially volume properties can be non-destructively and quantita-tively analysed which are non-accessible by other methods. These possibilities are used to study time dependent properties of corrosion. As an example concrete cylinders with embedded steel bars as working electrode are investigated. The mass loss of the working electrode is determined by CT and compared with results from electrochemical and gravimetric measurements. The limitations of the evaluation process of corrosion by CT are studied using a simulation program for the radiographic pro-jections. Introduction The progress in Computed Tomography (CT) applied for dimensional control, which has been reached in the last years, has opened new fields in materials characterization [1]. Especially volume properties can be non-destructively and quantitatively analysed which are non-accessibl...
ABSTRACT Bi-continuous porous ceramics for filtration applications possess a particularly complic... more ABSTRACT Bi-continuous porous ceramics for filtration applications possess a particularly complicated microstructure, with porosity and solid matter being intermingled. Mechanical, thermal, and filtration properties can only be precisely estimated if the morphology of both solid matter and porosity can be quantitatively determined. Using x-ray absorption and refraction, we quantitatively evaluate porosity and pore orientation in cordierite diesel particulate filter ceramics. Porosity values turn out to agree with mercury intrusion measurements, while pore orientation factors agree with published crystallographic texture data.
The Final Gravettian level (level 2) of the abri Pataud (Dordogne, France) yielded a large assemb... more The Final Gravettian level (level 2) of the abri Pataud (Dordogne, France) yielded a large assemblage of body ornaments that consists essentially of 85 quite standardized rectangular beads. Some uncertainty remained about the raw material in which these small beads were made: mammoth ivory, reindeer antler or bone? Non-invasive methods were employed in order to determine the raw material. First chemical analyses using microbeam Proton Induced X-ray Emission analysis (microPIXE) did not enable us to conclude definitively. Therefore, synchrotron and laboratory X-ray microtomography (microCT) were applied on eight beads and allowed us to identify ivory for all of them except for one, which shows slightly different morphological features. Due to their association with the human remains of level 2, these rectangular beads could be considered, like other “extraordinary” objects, as mortuary deposits. In this level, bones and reindeer antler are very abundant whereas mammoth ivory is rare:...
Le niveau 2 du site de l’abri Pataud (Les Eyzies-de-Tayac, Dordogne), daté du Gravettien final (-... more Le niveau 2 du site de l’abri Pataud (Les Eyzies-de-Tayac, Dordogne), daté du Gravettien final (-22 000 BP) a livré un nombre important d’éléments de parure dont l’essentiel correspond à 85 perles rectangulaires assez standardisées. Ces pièces étant de très petites dimensions (6 à 10 mm de longueur) et fortement polies, certaines incertitudes demeuraient quant à la matière première employée pour leur réalisation : os, bois de renne ou ivoire de mammouth ? Afin de déterminer la nature des matières dures d’origine animale utilisées, des méthodes d’examen non-invasives ont été employées sur des perles, sur des matériaux actuels et paléolithiques provenant du même niveau archéologique. L’analyse par émission des rayons X (PIXE) permettant une analyse non-invasive de la composition chimique au niveau des éléments majeurs, mineurs et traces, et la microtomographie X (microCT) permettant un examen micromorphologique non-destructif, ont été réalisées respectivement à l’aide de l’accélérateu...
We present, for the first time, Doppler-maps of the asynchronous polars BY Camelopardalis and V14... more We present, for the first time, Doppler-maps of the asynchronous polars BY Camelopardalis and V1432 Aquilae. BY Cam and V1432 Aql belong to a four member subclass of asynchronous polars, where orbital and spin period of the white dwarf differ by ~ 1 %. Contrary to their synchronized relatives, the ballistic accretion stream encounters a changing orientation of the magnetic-field during a beat cycle. As a consequence, infalling matter should be threaded onto different field lines, and directed to the energetically favoured pole. We obtained sets of high resolution (≈ 0.7Å ), phase-resolved (Deltaphi ≈ 0.01) spectra of both systems at the 3.5 m telescope at Calar Alto with the TWIN spectrograph. The resulting Doppler-maps for both stars show no clear signatures of the ballistic and/or magnetic accretion stream frequently detected in tomograms of synchronized systems. Instead the emission is spread over a wide range of velocities. This is most probably an indication of matter not accreted in a single stream, but via a curtain extending over a wide range in azimuth. We also find evidence for the heated side of the secondary star for BY Cam, from which the Doppler-maps could be phased.
Precautions in the generation of surfaces from CT images should be the rule. Two different data s... more Precautions in the generation of surfaces from CT images should be the rule. Two different data sets of the bust of Nefertiti and addi tional data from an industrial CT scanner will show the conflicts that arise when defining a surface. The recent trend in CT is to extract surfaces from CT measurements which can compete with the accuracy of
Due to the progress in Computed Tomography (CT) applied for dimensional control new fields in ma-... more Due to the progress in Computed Tomography (CT) applied for dimensional control new fields in ma-terials characterization are opened. Especially volume properties can be non-destructively and quantita-tively analysed which are non-accessible by other methods. These possibilities are used to study time dependent properties of corrosion. As an example concrete cylinders with embedded steel bars as working electrode are investigated. The mass loss of the working electrode is determined by CT and compared with results from electrochemical and gravimetric measurements. The limitations of the evaluation process of corrosion by CT are studied using a simulation program for the radiographic pro-jections. Introduction The progress in Computed Tomography (CT) applied for dimensional control, which has been reached in the last years, has opened new fields in materials characterization [1]. Especially volume properties can be non-destructively and quantitatively analysed which are non-accessibl...
ABSTRACT Bi-continuous porous ceramics for filtration applications possess a particularly complic... more ABSTRACT Bi-continuous porous ceramics for filtration applications possess a particularly complicated microstructure, with porosity and solid matter being intermingled. Mechanical, thermal, and filtration properties can only be precisely estimated if the morphology of both solid matter and porosity can be quantitatively determined. Using x-ray absorption and refraction, we quantitatively evaluate porosity and pore orientation in cordierite diesel particulate filter ceramics. Porosity values turn out to agree with mercury intrusion measurements, while pore orientation factors agree with published crystallographic texture data.
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Papers by Andreas Staude