The study of the influence of micro-arc oxidation modes on the morphology and parameters of an oxide coating on the D16AT aluminum alloy

An effective way to protect valve metals and their alloys is the micro-arc oxidation method (MAO), which is currently used in various industries. However, to achieve the desired characteristics and properties of oxide coatings, a large number of experiments are required to determine an optimal oxidation mode, which makes the MAO method labor-intensive and resource-consuming. One of the ways to solve this problem is the search for an informative parameter or several parameters, the use of which during the oxidation process monitoring allows identifying a relationship between the MAO modes and the specified characteristics of oxide coatings. This paper studies the influence of the specified technological MAO modes (current density, oxidation time, amplitude of acoustic emission (AE) signals recorded during MAO) on the morphology and parameters of oxide coatings (thickness δ and surface roughness Ra) deposited on the D16AT aluminum alloy clad with pure aluminum. Multivariate planning of an experiment and the performed regression analysis allowed establishing a relationship between two oxidation factors (current density and oxidation time) and the parameters of the produced coatings. The authors proposed an additional factor, which is determined in the monitoring mode during the oxidation process as the time from the moment when the maximum or minimum of the acoustic emission (AE) amplitude recorded in the MAO process is reached until the end of the oxidation process. The study established that the introduction of an additional factor allows increasing significantly the reliability of the dependence between the coating parameters obtained experimentally and by the computational method based on the regression analysis. The authors note that when performing MAO, with the additional use of the MAO process monitoring by recording the AE amplitude, it is possible to achieve a high reliability between the calculated and actual values of the parameters of oxide coatings

3D Printing Technique-Improved Phase-Sensitive OTDR for Breakdown Discharge Detection of Gas-Insulated Switchgear

In this paper, we propose and demonstrate a gas-insulated switchgear (GIS) breakdown discharge detection system based on improved phase-sensitive optical time domain reflectometry (φ-OTDR) assisted by 3D-printed sensing elements. The sensing element is manufactured by a material with a high Poisson ratio for enhancement of the sensitivity of φ-OTDR to the acoustic emission detection during the breakdown discharge process. In our experiment, seven 3D-printed sensing elements incorporating with optical fibers are attached tightly onto the shell of the GIS, which are monitored by φ-OTDR to localize and detect the acoustic emission signal resulted from the breakdown discharge. Ultimately, thanks to the phase demodulation, acoustic signals induced by the breakdown discharge process can be captured and recovered. Furthermore, the time delay analysis of detected signals acquired by different sensing elements on the GIS breakdown discharge unit is able to distinguish the location of the insulation failure part in the GIS unit. It suggests that the φ-OTDR incorporated with 3D printing technology shows the advantage of robustness in GIS breakdown discharge monitoring and detection

WOFEX 2021 : 19th annual workshop, Ostrava, 1th September 2021 : proceedings of papers

The workshop WOFEX 2021 (PhD workshop of Faculty of Electrical Engineer-ing and Computer Science) was held on September 1st September 2021 at the VSB – Technical University of Ostrava. The workshop offers an opportunity for students to meet and share their research experiences, to discover commonalities in research and studentship, and to foster a collaborative environment for joint problem solving. PhD students are encouraged to attend in order to ensure a broad, unconfined discussion. In that view, this workshop is intended for students and researchers of this faculty offering opportunities to meet new colleagues.Ostrav

Large space structures and systems in the space station era: A bibliography with indexes

Bibliographies and abstracts are listed for 1219 reports, articles, and other documents introduced into the NASA scientific and technical information system between July 1, 1990 and December 31, 1990. The purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems

Safety and Reliability - Safe Societies in a Changing World

The contributions cover a wide range of methodologies and application areas for safety and reliability that contribute to safe societies in a changing world. These methodologies and applications include: - foundations of risk and reliability assessment and management - mathematical methods in reliability and safety - risk assessment - risk management - system reliability - uncertainty analysis - digitalization and big data - prognostics and system health management - occupational safety - accident and incident modeling - maintenance modeling and applications - simulation for safety and reliability analysis - dynamic risk and barrier management - organizational factors and safety culture - human factors and human reliability - resilience engineering - structural reliability - natural hazards - security - economic analysis in risk managemen