Temat: direct current - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Influence of element’s parameters on the output characteristics of the voltage multiplier when powered from the inverter in resonance conditions
Autorzy:: Mućko, Jan
Tematy:: high direct current voltage generator
DC
direct current
output characteristics
resonant inverter
voltage multiplier; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/59111794.pdf Link otwiera się w nowym oknie
Opis:: The article presents the influence of the parameters of the high voltage direct current (HVDC) generator with a multiplier, such as: leakage inductance of the high voltage (HV) transformer, capacitance, and the number of multiplier stages on the value of the output voltage, voltage ripple, power and frequency of the supply voltage as a function of the output current. The presented characteristics were obtained under the synchronization conditions of the inverter output voltage and current that powers the multiplier. The presented results will be useful when designing HVDC generators with Cockcroft-Walton multipliers.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Zastosowanie Silników BLDC (ang. BrushLess Direct-Current motor) we współczesnych napędach elektrycznych i w motoryzacji
The use of BLDC Motors (Brushless Direct-Current Motor) in modern electric drives in the automotive industry
Autorzy:: Budziłowicz, A.
Tematy:: silniki BLDC
BrushLess Direct-Current motor
motoryzacja
napęd elektryczny
BLDC motors
brushless direct current motor
automotive
electric drive; Pokaż więcej
Wydawca:: Instytut Naukowo-Wydawniczy "SPATIUM"
Powiązania:: https://bibliotekanauki.pl/articles/313405.pdf Link otwiera się w nowym oknie
Opis:: W artykule przedstawiono zasadę działania silników BLDC, wspomniano rys historyczny ww silników, ponadto przedstawiono podział podstawowy, jak i dodatkowy silników BLDC. Dodatkowo przedstawiono w sposób usystematyzowany parametry elektryczne i mechaniczne silników BLDC. Porównano omawiane silniki BLDC z innymi typami silników, a szczególnie z silnikami szczotkowymi. Na koniec przedstawiono obszar zastosowania silników BLDC ze szczególnym uwzględnieniu współczesnych napędów elektrycznych w motoryzacji.
The article presents the operating principle of BLDC motors, the above mentioned historical development of BLDC motors, also presented a basic and additional division of BLDC motors. In addition, it presents in a parameters electrical and mechanical BLDC motors. BLDC motors discussed compared with other types of engines, especially brush DC motors. Finally, afield of application of BLDC motors with particular regard to the modern electric drives in the automotive industry.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Anodal transcranial direct current stimulation (tDCS) over the left DLPFC improves emotion regulation
Autorzy:: Hansenne, Michel
Weets, Emilie
Tematy:: emotion regulation
transcranial direct current stimulation
DLPFC; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/2121946.pdf Link otwiera się w nowym oknie
Opis:: The study of emotion regulation constitutes a major area of research for having a complete picture of human emotional experience, and several lines of evidence claim that poor emotion regulation skills are particularly deleterious in different aspects of life. Previous tDCS studies have suggested the beneficial role of DLPFC stimulation to improve emotion processing and regulation. The present study was therefore conducted to confirm and extend the effects of DLPFC stimulation on emotion regulation by including both positive and negative emotional material. In this between subjects study, participants were randomly assigned to receive active or sham stimulation over the left DLPFC. Participants viewed negative, positive, and neutral pictures while attempting to decrease, increase, or not modulate their emotional reactions. Subjective reactions were assessed via on-line ratings. The main results show that anodal tDCS stimulation over the left DLPFC slightly improves the ability to increase emotion perception for positive emotions. More interestingly, the results demonstrate that tDCS enhances the regulation of both positive and negative emotions when the baseline is considered. This study provides additional data on the use of tDCS as a tool to increase emotion regulation not only for negative affective material, but also for positive ones.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Direct current and pulsed direct current plasma nitriding of ferrous materials a critical review
Autorzy:: Łępicka, M.
Grądzka-Dahlka, M.
Tematy:: plasma nitriding
ion nitriding
direct current plasma nitriding
pulsed direct current
edge effect
azotowanie plazmowe
azotowanie jonowe
prąd stały impulsowy; Pokaż więcej
Wydawca:: Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Powiązania:: https://bibliotekanauki.pl/articles/386438.pdf Link otwiera się w nowym oknie
Opis:: Nowadays, the improvement of ferrous materials performance is a problem of high interest. One of well-known wear- and corrosion properties improving technique is plasma nitriding, in which elemental nitrogen is introduced to the surface of a metal part for subsequent diffusion into the material. As a result, a compound, “white” layer and a diffusion zone are formed at the detail’s surface. Most of the authors positively describe the effects of surface ion nitiding. On the other hand, there are also reports on adverse effects of direct current and pulsed direct current plasma nitriding on ferrous materials performance. Therefore, an attempt to provide comprehensive summary on direct current and pulsed direct current ion nitriding and its influence on ferrous materials’ mechanical and corrosion properties has been made. According to the results, some of the technique drawbacks are hard to avoid in mass production.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Selected Aspects of Short-Circuits in the DC Circuit of HVDC Systems in Transistor (VSC) and Thyristor (LCC) Technologies
Wybrane aspekty zwarć w obwodzie prądu stałego układów HVDC w technologii tranzystorowej (VSC) i tyrystorowej (LCC)
Autorzy:: Kosmecki, Michał
Madajewski, Krzysztof
Tematy:: direct current transmission system
HVDC
VSC
LCC
direct current
short-circuit
DC switch
układ przesyłowy prądu stałego
prąd stały
zwarcie
wyłącznik DC; Pokaż więcej
Wydawca:: ENERGA
Powiązania:: https://bibliotekanauki.pl/articles/952874.pdf Link otwiera się w nowym oknie
Opis:: The article addresses the problem of short-circuits in DC circuits of high voltage direct current (HVDC) transmission systems. The current state of HVDC technology development, including achievable parameters of semiconductor components, relevant for short-circuit strength, are presented. The differences between voltage source converter (VSC HVDC) topologies are described from the perspective of affecting the possibilities of switching off short-circuit currents and the results of simulation tests for selected topologies are presented. Responses of a system with a cable and overhead line to ground-fault of one or both poles are analysed and compared. The results of the analysis have shown that short-circuits in the DC circuits of a VSC HVDC system cause a rapid and very significant increase in the short-circuit current, which imposes high requirements on DC breakers that are starting to appear in field applications.
W artykule podjęto problem zwarć w obwodach DC układów przesyłowych prądu stałego na wysokim napięciu (HVDC). Przedstawiono aktualny stan rozwoju technologii HVDC, w tym osiągalne parametry elementów półprzewodnikowych, istotne z punktu widzenia wytrzymałości zwarciowej. Opisano różnice w topologiach przekształtników układów tranzystorowych (VSC HVDC) wpływające na możliwości wyłączania prądów zwarciowych oraz przedstawiono wyniki badań symulacyjnych dla wybranych z nich. Poddano analizie i porównano odpowiedzi układu z linią kablową i napowietrzną na zwarcie jednego bieguna lub obu biegunów do ziemi. Wyniki analiz pokazały, że zwarcia w obwodach prądu stałego układu VSC HVDC powodują szybki i bardzo znaczny wzrost prądu zwarciowego, co narzuca duże wymagania na wyłączniki DC, które dopiero zaczynają być w praktyce stosowane.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Wavelet analysis of on-dimensional traction signals
Autorzy:: Kozłowski, M.
Tematy:: tram driving system with direct current engines
adhesion failure
engine current
recognition; Pokaż więcej
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Powiązania:: https://bibliotekanauki.pl/articles/242386.pdf Link otwiera się w nowym oknie
Opis:: The article presents issues concerning the analysis of one-dimensional traction signals describing energy conversion processes in driving systems of electric traction vehicles. The method of FFT analysis has been compared to the wavelet method. The most crucial tasks have been discussed of wavelet analyses of signals connected with the problems of drive modelling. Fundamental tasks of coefficient analyses such as approximation, compression and denoising have been taken into account, as well as more complex tasks such as filtering band component and feature extraction. An example of analysis of current signal from tram driving system obtained in the conditions of tractive adhesion failure has been presented. A hypothesis has been demonstrated that coefficients obtained in subsequent stages of wavelet decomposition can constitute the basis for indicating electric current feature vector for the phenomenon of adhesion failure. Application has been proposed of simple characteristics of transform coefficients such as energy, number of zero transitions and power. A feature vector of coefficients has been chosen. A method of feature classification has been proposed in order to implement it in adhesion failure recognition. The results of verification of wavelet analysis application in adhesion failure recognition have been presented. As tance has been taken as to the results of the diagnosis taking into consideration currently used anti-slip systems of traction vehicles.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Variable-speed drive with series - excited motors in dynamic braking mode
Autorzy:: Kenessova, Perizat
Kaverin, Vladimir
Tatkeyeva, Galiya
Tematy:: electric motor
power section
direct current drive
alternating current drive
circuit design; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Powiązania:: https://bibliotekanauki.pl/articles/24200808.pdf Link otwiera się w nowym oknie
Opis:: Variable-speed DC drives with series-excited motors are widely used in the mining industry, transport and lifting equipment. The purpose of the study is to determine the dynamic characteristics of a variable direct current (DC) drive with a series-excited motor in the dynamic braking mode. In the article, there have been developed schematic diagrams of the power section that ensure stable braking of a variable-speed electric drive with a series-excited motor. The requirements for the braking mode have been developed. The studies have been carried out for a saturated and unsaturated magnetic circuit of an electric motor. The scientific novelty of the work consists in determining the zone of stable operation of the dynamic braking mode. As a result, there has been proposed technical implementation of the power section of a variable-speed electric drive with a series-excited motor that ensures stable braking. A special place in the study is the development of two models of an electric motor with subsequent excitation taking into account the saturation of the magnetic circuit - mathematical and simulation. Thus, the article has not only theoretical but also visual and practical significance in the context of already conducted studies on the subject. Options for the technical implementation of the braking regime were also considered in the course of the sequential implementation of the planned stages of the study.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Research on Distribution and Morphology of Primary Si Under the Effect of Direct Current
Autorzy:: Li, Jiayan
Njuguna, Benson Kihono
Ni, Ping
Wang, Liang
Tan, Yi
Tematy:: silicon source
direct current
Joule heating
Si morphology
Fe impurity; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/2049663.pdf Link otwiera się w nowym oknie
Opis:: A source of pure silicon was added into an alloy refining system during a refining process with the application of a direct electric current. The effect of the temperature difference between the graphite electrodes and the alloy was decreased. The temperature increase value (ΔT) of the Al-28.51wt.%Si alloy sample caused by Joule heating was calculated by weighing the mass of primary silicon. When the current density was 5.0×105A/m2, the overall temperature increase in the alloy was about 90°C regardless of the alloy composition. Adequate silicon atoms recorded the footprint of the electric current in the alloy melt. The flow convection generated by the electric current in the melt during the solidification process resulted in the refinement of primary silicon. The Fe impurity content in alloy refining without the electric current density was 2.16 ppm. However, it decreased to 1.27 ppmw with the application of an electric current density of 5.0×105A/m2.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Transcranial direct current stimulation as a new method for changing the accommodative response of the eye
Autorzy:: Wendel, M.
Burdziński, G.
Michalak, K. P.
Przekoracka-Krawczyk, A.
Tematy:: transcranial direct current stimulation
tDCS
accommodative response
visual training
visual cortex; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/173903.pdf Link otwiera się w nowym oknie
Opis:: The aim of the present study was to test if the exposure to transcranial direct current stimulation (tDCS) would change the excitability of the visual cortex and influence an accommodative response of the ocular lens. Twenty four subjects were divided into two groups: real-stimulation of the occipital cortex in which participants were exposed to real stimulation (1 mA for 12 min), and sham in which subjects were tested with placebo stimulation. The results showed that tDCS might indeed influence accommodative response. The strongest and most evident effect was observed when a 3.0 D accommodative stimulus was used: anodal tDCS increased but cathodal tDCS – decreased the accommodative response. The second finding was that the effect of stimulation was dependent on the examined eye. The right eye with slightly lower visual acuity and weaker accommodative response in pre-test, responded more strongly than the left eye. The short-time tDCS might modulate excitability of the neurons in visual cortex and eye sensitivity, reflected in the change of accommodative response. The tDCS method may be considered a technique that could reinforce conventional active visual training to improve accommodative functions.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: The impact of renewable energy sources on the overload of high voltage lines – power flow tracking versus direct current method
Autorzy:: Pijarski, Paweł
Saigustia, Candra
Kacejko, Piotr
Bena, Lubomir
Belowski, Adrian
Tematy:: current overload
direct current method
power flows
power line
sensitivity analyses
tracking power flows; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/59111809.pdf Link otwiera się w nowym oknie
Opis:: Studying the impact of renewable energy sources planned to be connected to the grid, requires the preparation of expert opinions. The task of this opinion is to verify that there are possibilities enabling the connection of the considered source to the network. Each opinion is required to take into account other facilities and those sources which were previously connected to the grid or connection agreement were signed with them. The need to take into account such a large number of sources contributes to potential thermal overloads of high-voltage lines. Sometimes these overloads are insignificant, but in certain situations it turns out that their occurrence may be a reason for refusing to sign connection agreements for new sources. According to network operators, their presence may constitute a threat to the operational security of the grid. The article presents the use of the method of tracking active power flows and the DC method of determining power flows to estimate the impact of these sources on thermal overloading of lines. Using of the IEEE-118 test network, selected nodes were analysed where connecting sources might significantly worsen overloads previously observed or would cause new overloads. The proposed approach will enable potential investors to make proper decisions regarding selection of source connection points. Combining the results obtained by both methods at the same time will allow for the indication of appropriate connection nodes for sources from the point of view of minimising the number of overloaded lines and prospective costs of their uprating.
Dostawca treści:: Biblioteka Nauki

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