38 research outputs found
Π€ΡΠ°ΠΊΡΠ°Π»ΡΠ½ΡΠΉ Π°Π½Π°Π»ΠΈΠ· ΠΌΠ½ΠΎΠ³ΠΎΠΌΠ΅ΡΠ½ΡΡ Π΄Π°Π½Π½ΡΡ Π² ΠΌΠ½ΠΎΠ³ΠΎΡΠ΅Π½ΡΠΎΡΠ½ΡΡ ΡΠΈΡΡΠ΅ΠΌΠ°Ρ
ΠΡΠ΅ΡΠ°ΡΠΈΠΎΠ½Π½Π°Ρ ΡΠΎΠΌΠΎΠ³ΡΠ°ΡΠΈΡ ΡΡΡΠ± Π² ΠΏΡΠΎΡΠ΅ΡΡΠ΅ ΡΠΊΡΠΏΠ»ΡΠ°ΡΠ°ΡΠΈΠΈ
The pipe wall thickness was estimated based on three-dimensional images of the pipe recovered from several X-ray projections, which were made in a limited angle of view. Since the effects of scattered radiation and beam hardening are up to 50 % of the main radiation, ignoring them leads to blur of the image and inaccuracy in determining dimensions. To restore pipe images from projections, a volume and/or shell representation of the pipe is used, as well as iterative Bayesian methods. Using these methods, the error in estimating the pipe wall thickness from the projection data can be equal to or less than 300 ΞΌm. It has been shown that standard X-ray projections on the film or imaging plates used to obtain data can be used to restore pipe wall thickness profiles in factory conditions.ΠΡΠΎΠ²Π΅Π΄Π΅Π½Π° ΠΎΡΠ΅Π½ΠΊΠ° ΡΠΎΠ»ΡΠΈΠ½Ρ ΡΡΠ΅Π½ΠΊΠΈ ΡΡΡΠ±Ρ, ΠΈΡΡ
ΠΎΠ΄Ρ ΠΈΠ· ΡΡΠ΅Ρ
ΠΌΠ΅ΡΠ½ΡΡ
ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΠΉ ΡΡΡΠ±Ρ, Π²ΠΎΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Π½ΡΡ
ΠΈΠ· Π½Π΅ΡΠΊΠΎΠ»ΡΠΊΠΈΡ
ΡΠ΅Π½ΡΠ³Π΅Π½ΠΎΠ²ΡΠΊΠΈΡ
ΠΏΡΠΎΠ΅ΠΊΡΠΈΠΉ, ΠΊΠΎΡΠΎΡΡΠ΅ Π±ΡΠ»ΠΈ Π²ΡΠΏΠΎΠ»Π½Π΅Π½Ρ Π² ΠΎΠ³ΡΠ°Π½ΠΈΡΠ΅Π½Π½ΠΎΠΌ ΡΠ³Π»Π΅ ΠΎΠ±Π·ΠΎΡΠ°. ΠΠΎΡΠΊΠΎΠ»ΡΠΊΡ ΡΡΡΠ΅ΠΊΡΡ ΡΠ°ΡΡΠ΅ΡΠ½Π½ΠΎΠ³ΠΎ ΠΈΠ·Π»ΡΡΠ΅Π½ΠΈΡ ΠΈ ΡΠΆΠ΅ΡΡΠΎΡΠ΅Π½ΠΈΡ Π»ΡΡΠ΅ΠΉ ΡΠΎΡΡΠ°Π²Π»ΡΡΡ Π΄ΠΎ 50 % ΠΎΡ ΠΎΡΠ½ΠΎΠ²Π½ΠΎΠ³ΠΎ ΠΈΠ·Π»ΡΡΠ΅Π½ΠΈΡ, ΠΈΡ
ΠΈΠ³Π½ΠΎΡΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡ ΠΊ ΡΠ°Π·ΠΌΡΡΠΈΡ ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΡ ΠΈ Π½Π΅ΡΠΎΡΠ½ΠΎΡΡΠΈ ΠΏΡΠΈ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΠΈ ΡΠ°Π·ΠΌΠ΅ΡΠΎΠ². ΠΠ»Ρ Π²ΠΎΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΈΡ ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΠΉ ΡΡΡΠ± ΠΈΠ· ΠΏΡΠΎΠ΅ΠΊΡΠΈΠΉ ΠΏΡΠΈΠΌΠ΅Π½ΡΡΡΡΡ ΠΎΠ±ΡΠ΅ΠΌΠ½ΠΎΠ΅ ΠΈ/ΠΈΠ»ΠΈ ΠΎΠ±ΠΎΠ»ΠΎΡΠ΅ΡΠ½ΠΎΠ΅ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½ΠΈΠ΅ ΡΡΡΠ±Ρ, Π° ΡΠ°ΠΊΠΆΠ΅ ΠΈΡΠ΅ΡΠ°ΡΠΈΠ²Π½ΡΠ΅ Π±Π°ΠΉΠ΅ΡΠΎΠ²ΡΠΊΠΈΠ΅ ΠΌΠ΅ΡΠΎΠ΄Ρ. ΠΡΠΈ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠΈ ΡΡΠΈΡ
ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ² ΠΎΡΠΈΠ±ΠΊΠ° ΠΎΡΠ΅Π½ΠΊΠΈ ΡΠΎΠ»ΡΠΈΠ½Ρ ΡΡΠ΅Π½ΠΊΠΈ ΡΡΡΠ±Ρ ΠΈΠ· ΠΏΡΠΎΠ΅ΠΊΡΠΈΠΎΠ½Π½ΡΡ
Π΄Π°Π½Π½ΡΡ
ΠΌΠΎΠΆΠ΅Ρ Π±ΡΡΡ ΡΠ°Π²Π½ΠΎΠΉ ΠΈΠ»ΠΈ ΠΌΠ΅Π½ΡΡΠ΅ 300 ΠΌΠΊΠΌ. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΡΠ΅ ΡΠ΅Π½ΡΠ³Π΅Π½ΠΎΠ²ΡΠΊΠΈΠΌ ΠΈΠ·Π»ΡΡΠ΅Π½ΠΈΠ΅ΠΌ ΡΡΠ°Π½Π΄Π°ΡΡΠ½ΡΠ΅ ΠΏΡΠΎΠ΅ΠΊΡΠΈΠΈ Π½Π° ΠΏΠ»Π΅Π½ΠΊΠ΅ ΠΈΠ»ΠΈ Π²ΠΈΠ·ΡΠ°Π»ΠΈΠ·ΠΈΡΡΡΡΠΈΡ
ΠΏΠ»Π°ΡΡΠΈΠ½Π°Ρ
, ΠΏΡΠΈΠΌΠ΅Π½ΡΠ΅ΠΌΡΡ
Π΄Π»Ρ ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΈΡ Π΄Π°Π½Π½ΡΡ
, ΠΌΠΎΠ³ΡΡ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°ΡΡΡΡ Π΄Π»Ρ Π²ΠΎΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΈΡ ΠΏΡΠΎΡΠΈΠ»Π΅ΠΉ ΡΠΎΠ»ΡΠΈΠ½ ΡΡΠ΅Π½ΠΎΠΊ ΡΡΡΠ± Π² Π·Π°Π²ΠΎΠ΄ΡΠΊΠΈΡ
ΡΡΠ»ΠΎΠ²ΠΈΡΡ
Limited Projection 3D X-Ray Tomography Using the Maximum Entropy Method
It is well known from physics that the reconstruction of physical quantities from experimental data is often obstructed by incomplete information, the presence of noise and the ill-posed nature of the inversion problem. It was shown [1] that a Bayesian reconstruction (BR) in terms of the Maximum Entropy Method (MEM) combined with unbiased a priori knowledge, if available, is one way to overcome the difficulties. Similar problems occur while extracting useful information from incomplete data sets in technical applications. The solution of the deduced iteration procedure, if converged, gives the most probable one among all possible solutions. In case of radiographic techniques difficulties occur if there is no free access around the object or if the number of available radiographic projections is limited due to other reasons like restricted maximum exposure as often required for medical applications or economical aspects. This situation, characterized by a significant lack of data, makes it impossible to apply reconstruction algorithms which are usually used for computer tomography (CT). Other reconstruction algorithms can be found by introducing prior information (compare [1β6]) about the object and the structures of interest. Those algorithms meet practical requirements like robustness, reduction of experimental and numerical effort, or others. For NDE applications, e.g. the inspection of welds or castings, prior knowledge can be introduced from a practical point of view by assuming a binary or multi-material structure. This reduces significantly the number of permissible solutions and therefore the number of required radiographie projections.</p
ΠΡΠ΅ΡΠ°ΡΠΈΠΎΠ½Π½Π°Ρ ΠΏΠ°ΡΠ°Π»Π»Π΅Π»ΡΠ½Π°Ρ ΡΠ΅ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΡ ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΠΉ Π½Π° ΠΊΠ»Π°ΡΡΠ΅ΡΠ΅ OPENPOWER
Now one of the most important tasks is development and adaptation of iterative methods for the solution of the big rarefied systems of the algebraic equations. The problem of iterative parallel reconstruction of three-dimensional images of industrial facilities leads to such computing tasks. The fact that iterative methods of the solution of computing problems of big dimension are implemented on parallel structures much more effectively is important than direct methods of their decision. In this work the synchronous parallel algorithm is described, based on use of the MPI system for the solution of a problem of reconstruction of three-dimensional images of industrial facilities.Β Π Π½Π°ΡΡΠΎΡΡΠ΅Π΅ Π²ΡΠ΅ΠΌΡ ΠΎΠ΄Π½ΠΎΠΉ ΠΈΠ· Π½Π°ΠΈΠ±ΠΎΠ»Π΅Π΅ Π²Π°ΠΆΠ½ΡΡ
Π·Π°Π΄Π°Ρ ΡΠ²Π»ΡΠ΅ΡΡΡ ΡΠ°Π·ΡΠ°Π±ΠΎΡΠΊΠ° ΠΈ Π°Π΄Π°ΠΏΡΠ°ΡΠΈΡ ΠΈΡΠ΅ΡΠ°ΡΠΈΠΎΠ½Π½ΡΡ
ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ² Π΄Π»Ρ ΡΠ΅ΡΠ΅Π½ΠΈΡ ΡΠ²Π΅ΡΡ
Π±ΠΎΠ»ΡΡΠΈΡ
ΡΠ°Π·ΡΠ΅ΠΆΠ΅Π½Π½ΡΡ
ΡΠΈΡΡΠ΅ΠΌ Π°Π»Π³Π΅Π±ΡΠ°ΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΡΠ°Π²Π½Π΅Π½ΠΈΠΉ. Π ΡΠ°ΠΊΠΈΠΌ Π²ΡΡΠΈΡΠ»ΠΈΡΠ΅Π»ΡΠ½ΡΠΌ Π·Π°Π΄Π°ΡΠ°ΠΌ ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡ Π·Π°Π΄Π°ΡΠ° ΠΈΡΠ΅ΡΠ°ΡΠΈΠΎΠ½Π½ΠΎΠΉ ΠΏΠ°ΡΠ°Π»Π»Π΅Π»ΡΠ½ΠΎΠΉ ΡΠ΅ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠΈ ΡΡΠ΅Ρ
ΠΌΠ΅ΡΠ½ΡΡ
ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΠΉ ΠΏΡΠΎΠΌΡΡΠ»Π΅Π½Π½ΡΡ
ΠΎΠ±ΡΠ΅ΠΊΡΠΎΠ². ΠΠ°ΠΆΠ½ΡΠΌ ΡΠ²Π»ΡΠ΅ΡΡΡ ΡΠΎ, ΡΡΠΎ ΠΈΡΠ΅ΡΠ°ΡΠΈΠΎΠ½Π½ΡΠ΅ ΠΌΠ΅ΡΠΎΠ΄Ρ ΡΠ΅ΡΠ΅Π½ΠΈΡ Π²ΡΡΠΈΡΠ»ΠΈΡΠ΅Π»ΡΠ½ΡΡ
Π·Π°Π΄Π°Ρ Π±ΠΎΠ»ΡΡΠΎΠΉ ΡΠ°Π·ΠΌΠ΅ΡΠ½ΠΎΡΡΠΈ ΡΠ΅Π°Π»ΠΈΠ·ΡΡΡΡΡ Π½Π° ΠΏΠ°ΡΠ°Π»Π»Π΅Π»ΡΠ½ΡΡ
ΡΡΡΡΠΊΡΡΡΠ°Ρ
Π½Π°ΠΌΠ½ΠΎΠ³ΠΎ Π±ΠΎΠ»Π΅Π΅ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎ, ΡΠ΅ΠΌ ΠΏΡΡΠΌΡΠ΅ ΠΌΠ΅ΡΠΎΠ΄Ρ ΠΈΡ
ΡΠ΅ΡΠ΅Π½ΠΈΡ. Π ΡΡΠΎΠΉ ΡΠ°Π±ΠΎΡΠ΅ ΠΎΠΏΠΈΡΠ°Π½ ΡΠΈΠ½Ρ
ΡΠΎΠ½Π½ΡΠΉ ΠΏΠ°ΡΠ°Π»Π»Π΅Π»ΡΠ½ΡΠΉ Π°Π»Π³ΠΎΡΠΈΡΠΌ, ΠΎΡΠ½ΠΎΠ²Π°Π½Π½ΡΠΉ Π½Π° ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠΈ ΡΠΈΡΡΠ΅ΠΌΡ MPI Π΄Π»Ρ ΡΠ΅ΡΠ΅Π½ΠΈΡ Π·Π°Π΄Π°ΡΠΈ ΡΠ΅ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠΈ ΡΡΠ΅Ρ
ΠΌΠ΅ΡΠ½ΡΡ
ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΠΉ ΠΏΡΠΎΠΌΡΡΠ»Π΅Π½Π½ΡΡ
ΠΎΠ±ΡΠ΅ΠΊΡΠΎΠ²
THREE-DIMENSIONAL TOMOGRAPHIC RECONSTRUCTION OF FOUNDRY ARTICLES ON LIMITED MODEL AND EXPERIMENTAL DATA
The ways of overcoming of lack of source information, The ways of overcoming of lack of source information, allowing to reduce energy of primary X-radiation, necessaryΒ for radiography and to provide high quality of reconstruction, are offered