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The modelling of electric arc with stochastic disturbances. Part. 2, Simulating the impact of randomly disturbed models of electric arc on the welding system and power supply network

Sawicki Antoni

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2023

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Vol. 67, No. 3

57--68

EN

The article contains the justification for undertaking a study concerning the impact of random disturbances of AC arc on power supply systems of welding machines. In addition, the paper describes principles governing the development of arc macromodels using controlled voltage and current sources. Particular attention is paid to the magnitude of harmonic distortions of the THD+N signal (helpful in the quantitative assessment of the impact of randomly disturbed non-linear devices on supply networks). The article also presents macromodels of arcs corresponding to selected mathematical models, results of the simulated operation of these macromodels in the form of dynamic current-voltage characteristics and corresponding sets of measurement values of harmonic distortions of voltage. The study discussed in the article involved the investigation of processes occurring in the power supply system of the welding transformer loaded with randomly disturbed electric arc (found to be effective in the filtering of higher harmonics).

PL

W artykule podano uzasadnienie badania wpływu zaburzeń losowych łuku prądu przemiennego na układy zasilania urządzeń spawalniczych. Opisano zasady tworzenia makromodeli łuków z wykorzystaniem sterowanych źródeł napięciowych i prądowych. Szczególną uwagę zwrócono na wielkości zniekształceń harmonicznych sygnału THD+N, które są pomocne w ocenie ilościowej oddziaływań zaburzanych losowo urządzeń nieliniowych na sieci zasilające. Przedstawiono makromodele łuków, odpowiadające wybranym modelom matematycznym. Pokazano wyniki symulacji działania tych makromodeli w postaci charakterystyk napięciowo-prądowych dynamicznych. Dołączono odpowiadające im zestawy wartości pomiarowych zniekształceń harmonicznych napięcia. Zbadano procesy w układzie zasilania transformatora spawalniczego obciążonego zaburzanym losowo łukiem elektrycznym. Stwierdzono jego skuteczność w filtrowaniu wyższych harmonicznych.

2

Enhancing rheological muscle models with stochastic processes

Zagrodny Bartłomiej, Wojnicz Wiktoria, Ludwicki Michał, Baranski Robert

Acta of Bioengineering and Biomechanics

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2023

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Vol. 25, no. 3

EN

Biological musculoskeletal systems operate under variable conditions. Muscle stiffness, activation signals, and loads change during each movement. The presence of noise and different harmonic components in force production significantly influences the behaviour of the muscular system. Therefore, it is essential to consider these factors in numerical simulations.

3

Stochastic robust flight control under windshear by reduced-order anisotropic controller

Tchaikovsky M. M.

Archives of Control Sciences

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2009

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Vol. 19, no. 4

385-422

EN

This paper is devoted to design of stochastic robust anisotropy-based reduced-order controller for longitudinal flight control in landing approach under the influence of both deterministic and stochastic external disturbances. The control aims at disturbance attenuation and stabilizing aircraft longitudinal motion along some desired glidepath. The controller design procedure consists of two steps. At first, the full-order optimal controller is obtained as the solution to normalized anisotropy-based stochastic Η∞ optimization problem. Then, the optimal controller is reduced via a truncation-like technique. The results of comparison of reduced-order anisotropic controller with LQG and Η∞ ones on the base of closed-loop system simulation are presented.