The measurement of the velocity of abrasive particles at the suction part of cutting head

U svrhu optimiziranja konstrukcije abrazivne rezne glave primjenom numeričke simulacije, potrebno je prikupiti što više podataka o tome što se događa u reznoj glavi. U Institutu za geoniku u Ostravi upravo je u tijeku razvoj numeričkog modela postupaka koji se odvijaju u reznoj glavi abrazivnog vodenog mlaza tijekom stvaranja i formiranja abrazivnog vodenog mlaza. Za verifikaciju modela potrebno je, između ostalog, odrediti ponašanje abrazivnih čestica na ulazu u reznu glavu. Stoga se vizualizacija abrazivnih čestica na ulazu, pomoću različitih parametara abrazivnog mlaza i njegove analize, provela primjenom tehnike shadowgraphy (backlighting-pozadinsko osvjetljenje). Rezultati su prikazani u ovom radu.To be able to optimize the design of the abrasive cutting head using the numerical simulation, it is necessary to gather as much information about processes occurring in the cutting head as possible. The development of numerical model of processes occurring in the abrasive water jet cutting head during the process of creation and forming of an abrasive water jet is currently in progress at the Institute of Geonics in Ostrava. The verification of the model requires, among other things, to determinate the behaviour of abrasive particles at the input of a cutting head. Therefore, the visualisation of abrasive particles at the input using various parameters of abrasive jet and its subsequent analysis were performed using the shadowgraphy (backlighting) technique. The results are presented in the paper

Bezpecnost Elektronickych Pasu, Cast II.

The article discusses additional security features for protection of the sensitive biometric data stored in the electronic passports (i.e. fingerprints and irises). Two possible approaches are discussed - using symmetric and asymetric cryptography. The focus is given to the asymmetric methods as this is what the European proposal of the so called Extended Acess Control is based on.JRC.G.6-Sensors, radar technologies and cybersecurit

Speed Up of Volumetric Non-Local Transform-Domain Filter Utilising HPC Architecture

This paper presents a parallel implementation of a non-local transform-domain filter (BM4D). The effectiveness of the parallel implementation is demonstrated by denoising image series from computed tomography (CT) and magnetic resonance imaging (MRI). The basic idea of the filter is based on grouping and filtering similar data within the image. Due to the high level of similarity and data redundancy, the filter can provide even better denoising quality than current extensively used approaches based on deep learning (DL). In BM4D, cubes of voxels named patches are the essential image elements for filtering. Using voxels instead of pixels means that the area for searching similar patches is large. Because of this and the application of multi-dimensional transformations, the computation time of the filter is exceptionally long. The original implementation of BM4D is only single-threaded. We provide a parallel version of the filter that supports multi-core and many-core processors and scales on such versatile hardware resources, typical for high-performance computing clusters, even if they are concurrently used for the task. Our algorithm uses hybrid parallelisation that combines open multi-processing (OpenMP) and message passing interface (MPI) technologies and provides up to 283× speedup, which is a 99.65% reduction in processing time compared to the sequential version of the algorithm. In denoising quality, the method performs considerably better than recent DL methods on the data type that these methods have yet to be trained on

Patellofemoral pain syndrome assessed by Lysholm score, radiological and biorheometric measurements.

The aim of In this study was to verify the relationship among clinical indicators of patellofemoral pain syndrome (PFPS) and the results of modifying radiological investigation. Previous research suggests that there is a poor association between them. Therefore we have employed a technique for the functional evaluation of PFPS based on measuring the stiffness of the knee joint during passive flexion (biorheometry). The correlation between clinical examination and a standardized Lysholm score, radiological and biorheometric measures was investigated in the 28 knee joints of 14 subjects exhibiting clinical features of PFPS. A modified axial radiological projection of the patellofemoral articulation in 90° of flexion provided the parameters quantifying the anatomical - morphological arrangement of the patellofemoral joint. The biorheometric properties of the knee were evaluated using a custom made measuring apparatus during passive flexion and extension of the knee. Our results confirm that the link between the clinical findings and the X-ray imaging examinations was not evident. On the contrary, the biorheometric examination proved to correlate well with the clinical symptoms of PFPS. Parameters were identified which can characterize the biorheograms of people suffering PFPS. Analysis of the relationship among the clinical, radiological and biorheometric examinations leads to the recommendation that biorheometric examination is an effective method for the objective assessment of PFPS