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Robust estimation based nonlinear higher order sliding mode control strategies for PMSG-WECS

Nazir Awais, Khan Safdar Abbas, Khan Malak Adnan, Alam Zaheer, Khan Imran, Irfan Muhammad, Rehman Saifur, Nowakowski Grzegorz

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 5

art. no. e147063

EN

The wind energy conversion systems (WECS) suffer from an intermittent nature of source (wind) and the resulting disparity between power generation and electricity demand. Thus, WECS are required to be operated at maximum power point (MPP). This research paper addresses a sophisticated MPP tracking (MPPT) strategy to ensure optimum (maximum) power out of the WECS despite environmental (wind) variations. This study considers a WECS (fixed pitch, 3KW, variable speed) coupled with a permanent magnet synchronous generator (PMSG) and proposes three sliding mode control (SMC) based MPPT schemes, a conventional first order SMC (FOSMC), an integral back-stepping-based SMC (IBSMC) and a super-twisting reachability-based SMC, for maximizing the power output. However, the efficacy of MPPT/control schemes rely on availability of system parameters especially, uncertain/nonlinear dynamics and aerodynamic terms, which are not commonly accessible in practice. As a remedy, an off-line artificial function-fitting neural network (ANN) based on Levenberg-Marquardt algorithm is employed to enhance the performance and robustness of MPPT/control scheme by effectively imitating the uncertain/nonlinear drift terms in the control input pathways. Furthermore, the speed and missing derivative of a generator shaft are determined using a high-gain observer (HGO). Finally, a comparison is made among the stated strategies subjected to stochastic and deterministic wind speed profiles. Extensive MATLAB/Simulink simulations assess the effectiveness of the suggested approaches.

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XRD and STA Characterization of Phosphate Layers Deposited on the Carbon Steel Surface

Burduhos-Nergis Diana Petronela, Bejinariu Costica, Cazac Alin Marian, Sandu Andrei Victor, Vizureanu Petrica

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 3

955--960

EN

Carbon steel is one of the most widely used alloys in many industries, however, its use is limited by its low corrosion resistance. Depositing a layer of phosphate on its surface improves the corrosion resistance as well as other properties, such as wear resistance, adhesion etc. Accordingly, preliminary studies demonstrated that carbon steel coated with phosphate layers can be used in the manufacture of carabiners for various fields: civil engineering, oil industry etc. Whereas, to demonstrate their capacity to operate in severe conditions related to fire rescue and extinguishing operations, it is necessary to evaluate the thermal behaviour of these materials. Thus, the main goal of this paper is to study the behaviour at high temperatures of three different types of phosphate layers deposited on carbon steel surface, by STA analysis. Also, the paper aims to study the formation of different phosphate layers by determining the types of compounds formed after the completion of the phosphating process, by XRD analysis.

3

Influence of Curing Time on Properties of Dental Photosensitive Resin Applied in DLP Technique of 3D Printing

Redutko Joanna, Kalwik Aleksandra, Szarek Arkadiusz

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 2

419--424

EN

The article has presented the method of 3D Digital Light Processing printing as one of the technologies used for rapid prototyping of dental models and making elements of dentures. in this work the research was presented, which the aim was to determine the effect of additional exposure time on the properties of the obtained printouts. Dynamic Mechanical Analysis test showed significant differences in stiffness between uncured specimens as well as specimens cured for 10, 20 and 30 minutes. in turn the obtained TG and DTG curves allowed to determine the most optimal curing time for DLP printouts. These studies provide the basis for determining the most appropriate method for handling printouts after the process of printing from liquid resin, so that they are the best possible quality for dentists and prosthodontists.

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Wykorzystanie technik analizy termicznej w badaniach i doborze warunków przetwarzania tworzyw

Kurcok M.

Przetwórstwo Tworzyw

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2006

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[R.] 12, nr 4

119-126

PL

W artykule przedstawiono wybrane techniki z dziedziny analiz termicznych, które pozwalają na ocenę jakości surowców, dobór parametrów technologicznych przetwórstwa a niejednokrotnie wyjaśniają występowanie niepożądanych zjawisk związanych z przetwórstwem. Omówiono m.in. takie metody jak różnicową kalorymetrię skaningową DSC (Differential Scanning Calorimetry), technikę termograwimetrii TG (Thermal Gravimetry), także technikę różnicowej kalorymetrii skaningowej STA (Simultaneous Thermal Analyser) oraz technikę badania próbki pod wpływem obciążeń oscylacyjnych, tj. technikę dynamicznej analizy termomechanicznej DMA (Dynamic Mechanical Analysis).

EN

Selected techniques in the field of thermal analysis enabling the assessment of quality of raw materials, choosing technological parameters of plastics processing and in some cases the explanation of occurring of unwanted phenomena related to plastics processing were presented in the article. The following methods like: Differential Scanning Calorimetry - DSC, technique of Thermal Gravimetry - TG, technique of Simultaneous Thermal Analyser - STA and technique of testing of the sample under oscillatory loading, i.e. Dynamic Mechanical Analysis - DMA were discussed.