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12. Effects of jaw clenching and mental stress on persistent inward currents estimated by two different methodsRicardo N. O. Mesquita, Janet Taylor, Gabriel Trajano, Aleš Holobar, Basilio Gonçalves, Anthony Blazevich, 2023, izvirni znanstveni članek Opis: Spinal motoneuron firing depends greatly on persistent inward currents (PICs), which in turn are facilitated by the neuromodulators serotonin and noradrenaline. The aim of this study was to determine whether jaw clenching (JC) and mental stress (MS), which may increase neuromodulator release, facilitate PICs in human motoneurons. The paired motor unit (MU) technique was used to estimate PIC contribution to motoneuron firing. Surface electromyograms were collected using a 32-channel matrix on gastrocnemius medialis (GM) during voluntary, ramp, plantar flexor contractions. MU discharges were identified, and delta frequency (ΔF), a measure of recruitment–derecruitment hysteresis, was calculated. Additionally, another technique was used (VibStim) that evokes involuntary contractions that persist after cessation of combined Achilles tendon vibration and triceps surae neuromuscular electrical stimulation. VibStim measures of plantar flexor torque and soleus activity may reflect PIC activation. ΔF was not significantly altered by JC (p = .679, n = 18, 9 females) or MS (p = .147, n = 14, 5 females). However, all VibStim variables quantifying involuntary torque and muscle activity during and after vibration cessation were significantly increased in JC (p < .011, n = 20, 10 females) and some, but not all, increased in MS (p = .017–.05, n = 19, 10 females). JC and MS significantly increased the magnitude of involuntary contractions (VibStim) but had no effect on GM ΔF during voluntary contractions. Effects of increased neuromodulator release on PIC contribution to motoneuron firing might differ between synergists or be context dependent. Based on these data, the background level of voluntary contraction and, hence, both neuromodulation and ionotropic inputs could influence neuromodulatory PIC enhancement.
Ključne besede: electromyography, bistability, HD-EMG, input–output function, motor neuron
Objavljeno v DKUM: 22.05.2024; Ogledov: 100; Prenosov: 10
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14. Topološka optimizacija rotorske lamele sinhronskega motorja s potopljenimi trajnimi magneti : magistrsko deloDaniel Horvat, 2024, magistrsko delo Opis: Razvoj sodobnih pogonskih elektromotorjev na področju transporta predstavlja nove izzive. Potreba po doseganju visokih vrtljajev, navora in moči ob zagotovljenem dolgotrajnem obratovanju je prinesla k uporabi sinhronskih motorjev s potopljenimi trajnimi magneti. Magistrsko delo opisuje postopek topološke optimizacije rotorske lamele za omenjeni tip elektromotorjev, ki je potekal v programu CAESS ProTOp. Najbolj obremenjena območja rotorske lamele so mostički, ki morajo zadržati magnete pri vrtenju in zagotoviti mehansko stabilnost rotorja. Hkrati morajo biti dovolj tanki, da motor dosega potrebne elektromagnetne karakteristike. S topološko optimizacijo je bila pridobljena optimalna oblika mostičkov in manjša masa rotorske lamele. Rezultati topološke optimizacije so bili s pomočjo numeričnih simulacij v programu ANSYS primerjani z začetno, ročno optimizirano obliko rotorske lamele. Ugotovitve kažejo, da se s tanjšimi mostički optimalne oblike zmanjšajo napetosti in ekvivalentne plastične deformacije v kritičnih območjih. Uvedba sodobnih postopkov optimizacije v fazi razvoja lahko v prihodnosti zamenja proces ročnega iskanja optimalnih oblik in omogoči nov napredek na področju pogonskih elektromotorjev.
Ključne besede: topološka optimizacija, metoda končnih elementov, numerična simulacija, sinhronski motor s potopljenimi trajnimi magneti, CAESS ProTOp
Objavljeno v DKUM: 29.03.2024; Ogledov: 284; Prenosov: 0
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15. The dose–response relationship of quercetin on the motor unit firing patterns and contractile properties of muscle in men and womenKohei Watanabe, Shun Kunugi, Aleš Holobar, 2023, izvirni znanstveni članek Opis: Quercetin is one type of ergogenic aid and its effects on the neuromuscular system have recently attracted interest, but its dose-effect is not yet fully understood. The aim of this study was to examine the effect of different doses of quercetin ingestion on motor unit firing patterns and muscle contractile properties in humans. Thirteen young males and females conducted neuromuscular performance tests before (PRE) and 60 min after (POST) ingestions of 500 or 200 mg of quercetin glycosides (Qg500/Qg200, respectively) or placebo (PLA) on three different days. At PRE and POST, motor unit firing rates were calculated from high-density surface electromyography of the vastus lateralis muscle during 120-s isometric contraction of knee extension at 10% of maximal voluntary contraction. Electrically elicited forces in knee extensor muscles were also measured. After 60 s of voluntary contraction, motor unit firing rates, normalized by the exerted muscle force at POST, were significantly lower at POST than PRE with Qg500 and Qg200 (p < 0.05), but not with PLA (p > 0.05). Changes in motor unit firing rates normalized by the exerted force from PRE to POST were significantly greater with Qg500 than Qg200 at the end of contraction (p < 0.05). Under all three conditions, the electrically elicited force did not significantly change from PRE to POST (p > 0.05). These results suggest that both 500 and 200-mg quercetin ingestions alter motor unit firing patterns, and that quercetin’s effect is at least partially dose-dependent.
Ključne besede: ergogenic aids, nutritional supplementation, multichannel surface electromyography, motor unit identification, quercetin
Objavljeno v DKUM: 09.02.2024; Ogledov: 273; Prenosov: 19
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16. Tester preverjanja kota stikal, vezja AVD : magistrsko deloLuka Barković, 2024, magistrsko delo Opis: V magistrskem delu je razvita testirna naprava, ki ima možnost preverjanja položaja prispajkanih stikal na vezju AVD in odkrivanja slabih kosov. Za preverjanje položaja je uporabljen koračni motor, kateremu se štejejo koraki, ki se potem preračunajo v stopinje zaradi prikaza na zaslonu. Na osnovi števila korakov pri proženju stikal se določi odstopanje položaja stikal od željene vrednosti. Testirna naprava je narejena kot prototip na 3D-tiskalniku. Zagotovljen je zelo enostaven postopek testiranja, pri čemer se od uporabnika pričakuje zamenjava vezja po opravljenem testiranju in pritisk tipke za zagon testa.
Ključne besede: tester, krmilnik, koračni motor, kot, odstopanje
Objavljeno v DKUM: 06.02.2024; Ogledov: 408; Prenosov: 40
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17. Assessment of the operating characteristics of brushless dc motorsVasilija Sarac, Neven Trajchevski, Roman Golubovski, 2019, izvirni znanstveni članek Opis: This paper presents the operating characteristics of brushless DC motors (BLDC) obtained via analytical, numerical, and simulation software, enabling steady-state and transient characteristics of a motor to be computed. Based on the catalogue data from the producer, Moog, a motor is simulated in a closed-loop control system fed by a voltage inverter. The accuracy of the derived models is verified by comparison with data from the producer. The developed analytical and simulation models enable the studying of various motor operating modes, such as no-load, rated load, and locked rotor, including motor starting characteristics. They are universal and can be easily applied to any brushless DC motor by simple replacement of the motor parameters. A numerical model in FEM software verifies the accuracy of previously derived models by obtaining the motor operating characteristics and the magnetic flux density distribution in a cross-section of the motor. The results obtained from all models have verified the proper design of the motor and laid out the path for further improvement with respect to the various motor parameters or operating characteristics.
Ključne besede: brushless DC motor, FEM model, transient characteristics
Objavljeno v DKUM: 22.12.2023; Ogledov: 593; Prenosov: 6
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19. Response surface method-based optimization of outer rotor permanent magnet synchronous motorVahid Rafiee, Jawad Faiz, 2019, izvirni znanstveni članek Opis: The Finite Element Method (FEM) is a prominent analysis approach. Although it is applicable for simulation and optimization of electrical machines, FEM is a very time-consuming technique. One of the approaches to shorten the optimization runtime is the use of surrogate models instead of FEM. In this paper, the design and optimization of an outer rotor permanent magnet synchronous motor for a hybrid vehicle are investigated. Response surface methodology (RSM) with four input variables is integrated with a sequential quadratic programming algorithm for optimization. Before the optimization, the performance of the surrogate model in the prediction of untried points is validated. Finally, the optimal motor is simulated by FEM to verify the results of RSM-based optimization, and the outputs of both models are compared.
Ključne besede: response surface surrogate method, outer rotor permanent magnet synchronous motor, sequential quadratic programming optimization
Objavljeno v DKUM: 05.12.2023; Ogledov: 512; Prenosov: 4
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20. Pantograph driven with a linear induction motor with adaptive fuzzy controlCostica Nituca, Gabriel Chiriac, 2019, izvirni znanstveni članek Opis: This article presents an adaptive fuzzy control for a linear induction motor, which is used to control the vertical movement of a pantograph, which supplies an electric locomotive from a contact line. The system has the goal of eliminating all the discontinuity on the route, the resonance phenomenon, the separation of the pantograph head from the contact wire, and electric arches. The simulations demonstrate functional control of the pantograph driven with a linear induction motor system using fuzzy control techniques.
Ključne besede: linear induction motor, fuzzy control, locomotive pantograph, simulation
Objavljeno v DKUM: 05.12.2023; Ogledov: 279; Prenosov: 5
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