Diagnostics of electrical arc.

V úvodu této bakalářské práce je popsáno plazma, vysvětlen proces ionizace v plazmatu elektrického oblouku a popsány pružné a nepružné srážky. Další část je věnována elektrickému oblouku, jeho charakteristikám a popisu. Elektrický oblouk je obtížně předvídatelný a nepříznivý jev, který se objevuje u spínacích přístrojů, když rozpínáme nebo spínáme kontakty. Dále se práce zaměřuje na technickou diagnostiku. Tato kapitola se zabývá pojmem diagnostika, jejími přínosy v technice a následným vysvětlením základních pojmů v tomto oboru. Následně je zde zmíněna optická diagnostika oblouku, vysvětlení základních pojmů a popis starších metod používaných při vyhodnocování ekvidenzitogramů a následným sestrojením ekvidenzit. V závěru je zmíněna moderní metoda digitálního zpracování snímků a uveden příklad moderní vysokorychlostní kamery.The introduction of this bachelor thesis describes the plasma, explains the process of ionization in the plasma of the electric arc and describes the elastic and inelastic collisions. The next part is devoted to the electric arc, its characteristics and description. Electric arc is a difficult to predict and adverse phenomenon that occurs with switching devices when we open or close contacts. Furthermore, the work focuses on technical diagnostics. This chapter deals with the concept of diagnostics, its benefits in technology and the subsequent explanation of basic concepts in this field. Subsequently, the optical diagnostics of the arc, an explanation of the basic concepts and a description of older methods used in the evaluation of equidensitograms and the subsequent construction of equidensities are mentioned. Finally, a modern method of digital image processing is mentioned and an example of a modern high-speed camera is given.410 - Katedra elektroenergetikyvýborn

Zvýšení mechanických vlastností slitiny AlSiCuMg

Vydáno chybně pod ISSN 1210-047

Wetting of refractory ceramics with high-manganese and structural steel and description of interfacial interaction

This work aims to describe the interfacial interaction at the interface between refractory material and high-manganese (XT 720) and structural (11 523) steel using a wetting test up to 1600 degrees C. The contact angles were determined through the sessile drop method, and the results were put into context through degradation testing and the characterization of the interfacial interface by Energy Dispersive X-Ray (EDX), X-Ray Diffraction (XRD) analyses, and Scanning Electron Microscopy (SEM). The lowest resistance to molten steel was observed for chamotte materials, while the highest was observed for materials based on electrofused corundum. High-manganese steel was strongly erosive to the materials tested, with the wetting angle decreasing significantly from 10 to 103 degrees with decreasing Al2O3 content (an increase of 2.4 to 59.4% corundum) in the refractories. Structural steel showed wetting angles from 103 to 127 degrees for identical refractories. These results were consistent with the average erosion depth for Mn steel (0.2-7.8 mm) and structural steel (0-2.4 mm).Web of Science1212art. no. 178

Application of texture x-ray diffraction analysis in tectonic – an example of calcite preferred orientation quantifi cation in carbonate rocks

The goal of this work was to apply texture x-ray diffraction analysis to study naturally strained rocks, in which the quantification of main preferred orientation cannot be conducted by the optical methods. This method has mainly been developed for metallography and its application in geology has been very limited so far. Samples of the fine-grained limestone have been collected from an outcrop, in which the direction of tectonic movement has been known. Thus, the tectonic situation could be correlated with the data obtained by XRD texture analysis. Analyses have been done by two devices with different geometry of experiment. The first experiment (Schulz reflection geometry) needed correction for the gain data, because of tilting of the sample, which led to the misalignment of the sample from the x-ray beam direction. The second one (in-plane geometry) has been measured, when the sample has been fixed and rotated, thus the correction was not needed. The results in a form of pole figures reflect the mechanism of deformation. The orientation of cleavage planes of calcite parallel to foliation indicates a cataclastic flow. Thus, the method could be used to study deformation mechanisms. The asymmetry of the results can show sense of shear, but it could also reflect inhomogenities of the samples. The goal of this work was to apply texture x-ray diffraction analysis to study naturally strained rocks, in which the quantification of main preferred orientation cannot be conducted by the optical methods. This method has mainly been developed for metallography and its application in geology has been very limited so far. Samples of the fine-grained limestone have been collected from an outcrop, in which the direction of tectonic movement has been known. Thus, the tectonic situation could be correlated with the data obtained by XRD texture analysis. Analyses have been done by two devices with different geometry of experiment. The first experiment (Schulz reflection geometry) needed correction for the gain data, because of tilting of the sample, which led to the misalignment of the sample from the x-ray beam direction. The second one (in-plane geometry) has been measured, when the sample has been fixed and rotated, thus the correction was not needed. The results in a form of pole figures reflect the mechanism of deformation. The orientation of cleavage planes of calcite parallel to foliation indicates a cataclastic flow. Thus, the method could be used to study deformation mechanisms. The asymmetry of the results can show sense of shear, but it could also reflect inhomogenities of the samples

Application of texture x-ray diffraction analysis in tectonic – an example of calcite preferred orientation quantifi cation in carbonate rocks

The goal of this work was to apply texture x-ray diffraction analysis to study naturally strained rocks, in which the quantification of main preferred orientation cannot be conducted by the optical methods. This method has mainly been developed for metallography and its application in geology has been very limited so far. Samples of the fine-grained limestone have been collected from an outcrop, in which the direction of tectonic movement has been known. Thus, the tectonic situation could be correlated with the data obtained by XRD texture analysis. Analyses have been done by two devices with different geometry of experiment. The first experiment (Schulz reflection geometry) needed correction for the gain data, because of tilting of the sample, which led to the misalignment of the sample from the x-ray beam direction. The second one (in-plane geometry) has been measured, when the sample has been fixed and rotated, thus the correction was not needed. The results in a form of pole figures reflect the mechanism of deformation. The orientation of cleavage planes of calcite parallel to foliation indicates a cataclastic flow. Thus, the method could be used to study deformation mechanisms. The asymmetry of the results can show sense of shear, but it could also reflect inhomogenities of the samples. The goal of this work was to apply texture x-ray diffraction analysis to study naturally strained rocks, in which the quantification of main preferred orientation cannot be conducted by the optical methods. This method has mainly been developed for metallography and its application in geology has been very limited so far. Samples of the fine-grained limestone have been collected from an outcrop, in which the direction of tectonic movement has been known. Thus, the tectonic situation could be correlated with the data obtained by XRD texture analysis. Analyses have been done by two devices with different geometry of experiment. The first experiment (Schulz reflection geometry) needed correction for the gain data, because of tilting of the sample, which led to the misalignment of the sample from the x-ray beam direction. The second one (in-plane geometry) has been measured, when the sample has been fixed and rotated, thus the correction was not needed. The results in a form of pole figures reflect the mechanism of deformation. The orientation of cleavage planes of calcite parallel to foliation indicates a cataclastic flow. Thus, the method could be used to study deformation mechanisms. The asymmetry of the results can show sense of shear, but it could also reflect inhomogenities of the samples

PhD students´day FMST 2023

The authors gave oral presentations of their work online as part of a Doctoral Students’ Day held on 15 June 2023, and they reflect the challenging work done by the students and their supervisors in the fields of metallurgy, materials engineering and management. There are 82 contributions in total, covering a range of areas – metallurgical technology, thermal engineering and fuels in industry, chemical metallurgy, nanotechnology, materials science and engineering, and industrial systems management. This represents a cross-section of the diverse topics investigated by doctoral students at the faculty, and it will provide a guide for Master’s graduates in these or similar disciplines who are interested in pursuing their scientific careers further, whether they are from the faculty here in Ostrava or engineering faculties elsewhere in the Czech Republic. The quality of the contributions varies: some are of average quality, but many reach a standard comparable with research articles published in established journals focusing on disciplines of materials technology. The diversity of topics, and in some cases the excellence of the contributions, with logical structure and clearly formulated conclusions, reflect the high standard of the doctoral programme at the faculty.Ostrav

Electrochemical characterization of leached steel-making sludge

In this work, the electrochemical properties of the leached sludge, magnetite and zinc ferrite were studied. Acetic acid was used as a leaching reagent because, in recent years, there has been a surge of interest in using zinc-containing materials as photocatalysts, with acetic acid finding application in their preparation. Various methodological approaches were used, but the best results were achieved with a combination of 1-3 h leaching in 0.01 M acetic acid with a solid/liquid ratio of 500. In this arrangement, zincite was almost completely removed from the sludge, while zinc ferrite and magnetite remained in the solid residue. Ex situ analyses of the main leaching products were performed by X-ray diffraction, infrared spectroscopy, and thermogravimetry. The electrochemical behaviour of solid residue and model systems, that are micromagnetite and zinc ferrite, was studied in alkaline media by means of modified carbon paste electrodes, cyclic voltammetry, and chronocoulometry, with a suitable potential window ranging from 0 to 1.5 V. In summary, a linear dependence of the anodic and cathodic peak height on the square root of the scan rate was found. The position of the anodic and cathodic peaks shifted slightly with scan rate, only at low rates, up to 25 mV/s, the individual peaks coincided. The electrochemical response suggested a quasireversible process.Web of Science121art. no. 1669

Strengthening in patients with nonspecific low back pain

In the present work we compare the effectiveness of therapy in patients with chronic non-specific low back pain (CNLBP) using classical analytical strengthening and strengthening program based on principles of physiotherapy techniques that focus on the stabilization of the spine and are used in the treatment CNLBP. The experiment included a total of 14 patients diagnosed with CNLBP who were divided into two groups (n = 7), each of who underwent a 12-week training either classical or physiotherapy conceived strengthening. As for the evaluated parameters, we chose the size and quality of pain (visual analogue scale and Short Form McGill Pain Questionnaire), restrictions in daily life in relation to LBP (Oswestry Disability Index); we tried to capture a change in the stabilizing muscle function by using a collection of tests according to Kolar (2006). The evaluation took place at the beginning and after the program and then at intervals of six months. The results showed that there was a statistically significant improvement in both groups in the monitored parameters. The difference in results in pain intensity and functional limitations in life when comparing the two groups showed statistically insignificant. Both the groups of patients improved their score in the evaluation of the stabilizing functions of..

Effects of rehabilitation methods on the course of knee osteoarthritis

Knee osteoarthritis is the most often form of the progressive degenerative injury called osteoarthritis, which signifies the most widely extended knuckle disability all over the world. And so it turns into a serious healthy and social-economic problem. Besides the symptomatic treatment of pain, the effort of contemporary therapy is to affect those processes, which lead to osteoarthritis morphological progression. The medical treatment should be carried out preferably at total range and with rehabilitation as its integral part. This report sums up many till now published knowledge above knee osteoarthritis itself and above its treatment processes, primarily in case of use some rehabilitation methods, and offers some information above evaluation effect of therapeutical processes for course of this disorder. Powered by TCPDF (www.tcpdf.org

Restrictions on freedom to contract within company law

Katedra obchodního právaDepartment of Business LawFaculty of LawPrávnická fakult