Fully Automated Lumen Segmentation Method for Intracoronary Optical Coherence Tomography.

BACKGROUND: Optical coherence tomography (OCT) is an innovative imaging technique that generates high-resolution intracoronary images. In the last few years, the need for more precise analysis regarding coronary artery disease to achieve optimal treatment has made intravascular imaging an area of primary importance in interventional cardiology. One of the main challenges in OCT image analysis is the accurate detection of lumen which is significant for the further prognosis. METHOD: In this research, we present a new approach to the segmentation of lumen in OCT images. The proposed work is focused on designing an efficient automatic algorithm containing the following steps: preprocessing (artifacts removal: speckle noise, circular rings, and guide wire), conversion between polar and Cartesian coordinates, and segmentation algorithm. RESULTS: The implemented method was tasted on 667 OCT frames. The lumen border was extracted with a high correlation compared to the ground truth: 0.97 ICC (0.97-0.98). CONCLUSIONS: Proposed algorithm allows for fully automated lumen segmentation on optical coherence tomography images. This tool may be applied to automated quantitative lumen analysis.Peer Reviewe

SOLARIS National Synchrotron Radiation Centre in Krakow, Poland

The SOLARIS synchrotron located in Krakow, Poland, is a third-generation light source operating at medium electron energy. The first synchrotron light was observed in 2015, and the consequent development of infrastructure lead to the first users’ experiments at soft X-ray energies in 2018. Presently, SOLARIS expands its operation towards hard X-rays with continuous developments of the beamlines and concurrent infrastructure. In the following, we will summarize the SOLARIS synchrotron design, and describe the beamlines and research infrastructure together with the main performance parameters, upgrade, and development plans

Prediction of Fatigue Life of Welded Joints Made of Fine-Grained Martensite-Bainitic S960QL Steel and Determination of Crack Origins

Due to growing requirements connected with the utilization of advanced structures, nowadays the modern design processes are developed. One of the crucial issues considered in these processes is proper design of the joints against fatigue in order to fulfill a stated life of operation. In this study, the method of fatigue life prediction based on the criterion of permissible strain range in the notch root is presented. An engaged simplified model of fatigue life prediction was previously developed for mild and carbon steels. The evaluation made during the research has proven that this method can also be used for S960QL high-strength steel characterized by entirely different properties and structure. A considered theoretical model demonstrates satisfactory correlation with experimental data and safely describes the fatigue life of weldments. Furthermore, the predicted fatigue life of studied steel without welds shows great comparability with experimental data. The limit value of the strain range in the notch root was estimated. Below this value of strain, the fatigue life of welded joints is infinite, theoretically. Finally, the impact of the surface imperfections on the fatigue crack initiation was revealed. For paternal material, the origins of cracking were discovered at the places of nonmetallic scale particles. In welded joints, the fatigue cracks initiated at the whole length of the fusion line

Properties of welded joints made in high strength steel using laser technology

The usage of high strength steels (HSS) provides numerous benefits in the form of the cross- section area reduction causing weight decrease, improvement in exploitation parameters and in result positive financial effect. The most advantageous results are observed in the parts loaded by tensile stresses. The factors most influencing the fatigue strength of the metals, especially the steels of high value of yield point, are stress concentration in the originated geometrical notches, local changes of the stress state or the microstructure of paternal material. Improvement in the fatigue behaviour of HSS steels can be achieved by changing the commonly used technique for high-energy joining technology, namely laser beam welding. Relatively narrow welds and reduced heat-affected zone (HAZ) have minimized the residual stresses and distortions. The paper presents the results of the studies focused on mechanical properties of welded joints of high strength fine-grained steel S960QL. There was investigated the impact of heat input on the microstructure, microhardness- and residual stresses in the weld and HAZ. The crucial part is devoted to the fatigue research and fractographic investigation of the fatigue ruptures of laser-made welds. There were also found in the origins the cause of crack initiation. Keywords: mechanics, fatigue life, high strength steel, laser weldin

Mechanical Properties Analysis of Explosive Welded Sheet of AA2519-Ti6Al4V with Interlayer of AA1050 Subjected to Heat-Treatment

The paper presents results of investigations of welding sheets of AA2519-Ti6Al4V, a difficult-to-joint components materials, produced by explosive welding with a thin technological interlayer of AA1050. The joining process leads to the formation of intermetalics in the vicinity of joint and generates significant residual stresses. In the next step the laminate was subjected to a heat treatment process in order to improve the mechanical properties by precipitation hardening. This treatment should not be carried out before welding because of negative influence on a ductility of the aluminum alloy. Material in this state was subjected to the tests of chemical composition, microstructure, and microhardness. A tensile test was carried out with accompanying strain analysis by the digital image correlation (DIC) method. Moreover, the residual stresses were determined which were measured by using two methods, the X-ray diffraction and the hole drilling. This approach made it possible to measure the residual stresses both in the plane parallel to the surface and in the cross section of the laminate

Assessment of Effectiveness of Organo-Mineral Fertilizer Made of Coffee Spent Grounds and Biomass Ash

Optimization of the biodegradable wastes management is one of the main goals of the activities taken up in the European Union. The aim of the present paper is to define the possibilities of supporting the process of golden rod yield (Solidago canadensis L.) by using different mineral-organic fertilizers, in a form of granulated substances, produced from extracted coffee wastes (CSG) as well as from ash which is the result of woody biomass combustion. Golden rod, as a potential energetic plant, is very easy to grow because it covers the grounds which are not utilized agriculturally or the ones localised in the close neighbourhood of industrial areas. For certain experimental purposes, a field experiment was conducted. Six experimental plots constituted its basis, two experimental fertilizers based on the extracted coffee wastes (in the amount of 100g/m2), ash from the process of thermal biomass transition and two commercial fertilizers were applied. After 160 days of the experiment, the golden rod harvest was submitted to quantitative-qualitative analysis. An analysis of basic soil parameters (pH, EC, TOC) was also carried out and the content of significant elements, as far as fertilizers are concerned, N, P, K, Ca, Mg was analysed too. As a result of the conducted experiment, the yield rise was observed, both in the case of the plants fed with commercial fertilizers as well as the ones cultivated on the basis of the extracted wastes. Using fertilizers does not only allow for management of the wastes produced in farm areas but also enables to increase the achieved amount of golden rod crops as well as to boost energy that is sourced in the process of biomass used for energetic purposes

Effect of Shot Peening on the Low-Cycle Fatigue Behavior of an AA2519-T62 Friction-Stir-Welded Butt Joint

In this investigation, an AA2519-T62 FSW butt joint was subjected to shot peening with an air pressure of p = 0.6 MPa, a processing time of t = 10 min (per side), and a steel ball diameter of dk = 1.5 mm. In order to evaluate the impact of shot peening on the low-cycle behavior, the samples were tested with coefficient R = 0.1 at total strain amplitudes of 0.35%, 0.4%, and 0.5%. The shot-peened welds are characterized by a higher value of stress amplitude, a lower value of plastic strain amplitude, and their fatigue life increased slightly. The cyclic strength coefficient and the cyclic strain hardening exponent were reduced by 45% and 55%, respectively, as the result of the surface layer hardening. The shot peening process had no noticeable effect on the character of crack initiation and propagation. Almost in all cases, the cracking started in the area under the weld face, located close to the boundary between the thermo-mechanically affected zone and the stir zone at the advancing side. Only at the heaviest loadings (εac = 0.5%) were cracks initiated in the heat-affected zone at the retreating side. Despite the introduction of small cracks in the stir zone, their presence did not affect the decohesion character of the welded joint. Overall, it was observed that there is a minimal, positive impact of shot peening on the properties of the investigated joints