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Speed sensorless induction motor drive with predictive current controller
PublicationToday, speed sensorless modes of operation are becoming standard solutions in the area of electric drives. This paper presents a speed sensorless control system of an induction motor with a predictive current controller. A closed-loop estimation system with robustness against motor parameter variation is used for the control approach. The proposed algorithm has been implemented using field-programmable gate arrays (FPGAs) and a...
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Sensorless Control of Induction Machine Supplied by Current Source Inverter
PublicationThe paper describes the voltage control technique of induction machines supplied by a current source inverter. The control system is based on proposed new multi-scalar variables, which are named “r.” The control system contains the output filter capacitor's model. In the sensorless control system the Z type backstepping speed observer was applied. The mathematical dependences are confirmed by simulation and experimental research.
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3D scanning system for railway current collector contact strips
PublicationUndisturbed collection of current from a contact wire of the catenary constitutes one of the basic elements in reliable operation of electrified rail transport, particularly when vehicles move at high speed. Quality of current collection is influenced by the construction of catenary and current collectors, as well as by the technical condition and regulation of these two elements. Total contact force of a current collector head...
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Indirect Measurement of Motor Current Derivatives in PMSM Sensorless Drives
PublicationMotor current derivatives contain useful information for control algorithms, especially in sensorless electric drives. The measurement of motor current derivatives in electric motors supplied by voltage source inverter can be performed using di/dt transducers. However, in such a solution additional sensors have to be installed, e.g. Rogowski coils. Another approach is to measure current derivatives indirectly – by oversampling...
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Remarks on the Subject of Back-Up Protection of Residual Current Devices
PublicationResidual current devices without integral overcurrent protection (RCCBs) are back-up protected by fuses or miniature circuit-breakers (MCBs). If the latter are used, special attention must be given to the coordination between an RCCB and an MCB. This paper indicates probable cases of the aforementioned devices coordination, in which back-up protection of the RCCB is not adequate. A laboratory test has shown that depending on the...
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Modal analysis of railway current collectors using Autodesk Inventor
PublicationThe paper presents the results of modal analysis of railway current collector type 160EC. In the first place, the analysis was carried out analytically for a simplified two lumped mass pantograph model. Then numerical analysis was conducted in the Autodesk Inventor (AI) on the prepared multibody model using the AI modal analysis algorithm, which is based on the finite element method (FEM). Model elements which are most relevant...
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Determining the leakage current resistive component by the orthogonal vector method
PublicationThe measurement of the metal – oxide surge arresters (MOSA) leakage current and the analysis of its components is a key diagnostic criterion according to technical standards. During on site MOSA condition assessment, the easy way is based on the measurement only leakage current, without the inconvenient live working measurements of supply voltage. Orthogonal vectors method of determination the resistive leakage current is presented....
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Errors of a Linear Current Approximation in High-Speed PMSM Drives
PublicationCurrent sampling techniques and predictive algorithms used in the digital control of electric drives rely on a simple mathematical model that assumes linear current changes upon constant supplying voltages. This paper identifies rotor movement as a factor that makes this assumption invalid when the rotor covers an angular distance of a few tens of degrees during the control interval duration. The errors of the linear current approximation...
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Time-current tripping curves of arc fault detection devices
PublicationTripping curves of arc fault detection devices, in accordance with PN-EN 62606 “General requirements for arc fault detection devices” have been presented in the paper. Consequently the most fundamental differences in arc fault detection devices tripping compared to circuit-breakers and residual current devices have been indicated.
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Sensorless Control of Induction Motor Supplied by Current Source Inverter
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Low current transformer utilizing Co-based amorphous alloys
PublicationMetal oxide surge arresters have been widely used for protection of power system networks against overvoltages due to atmospheric discharges or malfunction of devices connected to the network. During its operation a surge arrester structure is degradated, what can be observed as an increase of a surge arrester leakage current. Paper presents an implementation of a new, high-permeability, Co64Fe4Ni1Si15B14 amorphous alloy as a current...
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Low Current Transformer Utilizing Co-Based Amorphous Alloys
PublicationMetal oxide surge arresters have been widely used for protection of power system networks against overvoltages due to atmospheric discharges or malfunction of devices connected to the network. During its operation a surge arrester structure is degradated, what can be observed as an increase of a surge arrester leakage current. Paper presents an implementation of a new, high-permeability, Co64Fe4Ni1Si15B14 amorphous alloy as a current...
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Mainstream shortcut N removal modeling current status and perspectives
PublicationThis work gives an overview of the state-of-the-art in modelling of short-cut processes for nitrogen removal in mainstream wastewater treatment and presents future perspectives for directing research efforts in line with the needs of practice. The modelling status for deammonification (i.e., anammox-based) and nitrite-shunt processes is presented with its challenges and limitations. The importance of mathematical models for considering...
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Behavior of residual current devices at frequencies up to 50 kHz
PublicationThe use of residual current devices (RCDs) is obligatory in many types of low-voltage circuits. They are devices that ensure protection against electric shock in the case of indirect contact and may ensure additional protection in the case of direct contact. For the latter purpose of protection, only RCDs of a rated residual operating current not exceeding 30 mA are suitable. Unfortunately, modem current-using equipment supplied...
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Security of Cryptocurrencies: A View on the State-of-the-Art Research and Current Developments
Publication[Context] The goal of security is to protect digital assets, devices, and services from being disrupted, exploited or stolen by unauthorized users. It is also about having reliable information available at the right time. [Motivation] Since the inception in 2009 of the first cryptocurrency, few studies have been undertaken to analyze and review the state-of-the-art research and current developments with respect to the security...
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Digital divide - inequalities in level of implementation of new information and telecommunication technologies. Cross country study
PublicationTekst stanowi analizę nierówności stopnia wdrożenia oraz implementacji ICTs w różnych krajach świata. Autor szacuje wskaźnik GINI dla możliwych krajów świata.In the paper presented, the author considers few aspects of the so-called "digital divide". It is easily noticeable worldwide, that new information and communication technologies (ICTs) "possess" a great ability to spread, at high pace, among countries from all around the...
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CURRENT HYPERTENSION REPORTS
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CURRENT ORGANIC CHEMISTRY
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Performance improvement method for the voltage-fed qZSI with continuous input current
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Bearing current path and pulse rate in PWM-inverter-fed induction
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MEDIUM-TERM WAVE AND CURRENT MODELLING FOR A MESOTIDAL WADDEN SEA COAST
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<title>Current developments of multicrucible technology of tailored optical fibers</title>
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Physical activity of future health care professionals: adherence to current recommendations
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IPMSM rotor position estimator based on analysis of phase current derivatives
PublicationThis paper describes an algorithm for estimation of IPMSM angular rotor position. The algorithm uses derivatives of motor phase currents resulting from PWM modulation to obtain the rotor position. The presented method is designed for medium- and high-speed range, since it is based on determination of the EMF vector. Algorithm is characterised by a very simple formulae. The calculation of rotor position is performed in every PWM...
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Analysis of Factors Having an Influence on Current in Non-Linear Inductive Brunch
PublicationArtykuł prezentuje analityczny opis pršdu włšczania nieliniowej gałęzi indukcyjnej. Analizę przeprowadzono w oparciu o odcinkowo-liniowš aproksymację charakterystyki magnesowania. Przeanalizowano wpływ chwili właczenia napięcia, charakteru obwodu i magnetyzmu szczštkowego rdzenia na przebieg i wartoć maksymalnš pršdu.
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Current methods and technologies for degradation of atrazine in contaminated soil and water: A review
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Minimization of Eddy Current Losses in a Straight Rectangular Cross Section Conductor
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Current-Voltage Characteristics of the Composites Based on Epoxy Resin and Carbon Nanotubes
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Quality assessments of electrochromic devices: the possibleuse of 1/f current noise
PublicationElementy wykorzystujące zjawisko elektrochromizmu, potrafiące zmieniać przezroczystość za pomocą ładowania/rozładowania ładunkiem elektrycznym, wykonano na bazie laminatów pokrytych porowatą strukturą tlenków Ni oraz tlenków Wi-V. Oba laminaty, na które naniesiono przewodzącą warstwę In2O3, przedzielono warstwą elektrolitu. Obserwowano szumy typu 1/f w prądzie I płynącym w trakcie rozładowywania urządzenia. Gęstość widmowa mocy...
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Photoenhanced current as a tool for investigating non-uniform structures of tetracene layer.
PublicationPowierzchniowe prądy fotowzmocnione używane były jako narzędzie do badań fizycznych własności powierzchni warstw od strony podłoża, a także od strony przeciwległej podłożu.
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Detection of stray current field interference on metal constructions using STFT
PublicationZaprezentowano metodę detekcji pola prądów błądzących wykorzystującą krótkoczasową transformatę Fouriera STFT. Ten sposób analizy umożliwia wyznaczenie zmian spektralnej gęstości mocy sygnału (np. potencjału konstrukcji) w funkcji czasu. Przedstawiono rezultaty analizy zmian potencjału w polu prądów błądzących generowanych przez trakcję tramwajową. Spektrogramy są kompozycją prążków w łącznej dziedzinie czasu i częstotliwości....
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A versatile analog CMOS cell: voltage - buffer /current - conveyor/ multiplier
PublicationW pracy przedstawiono koncepcję uniwersalnej komórki analogowej przeznaczonej dla programowalnych układów analogowych (FPAA). Komórka może pełnić funkcję bufora napięciowego, konwjora prądowego lub mnożnika analogowego. Układ przesymulowano w technologii CMOS 2 ćm.
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Investigations of non-uniform structure of the tetacene layer by photoen-hanced current
PublicationBadano stany pułapkujące nośniki w powierzchniowych obszarach warstwy tetra-cenu. W badaniach wykorzystano metodę prądów fotowzmocnionych. Wykazano obe-cność różnych rozkładów energetycznych pułapek przy obu powierzchniach war-stw tetracenu.
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Theoretical analysis of current induced by high-energetic radiation in dielectric materials
PublicationW pracy poddano analizie mechanizmy generacji i rekombinacji nośników ładunku w obecności wysokoenergetycznego promieniowania. Przedstawiono zależności gęstości prądu elektrycznego od natężenia promieniowania i napięcia polaryzujacego próbkę.
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Effect of contactless hybrid current limiter on voltage dips in power system
PublicationW referacie przedstawiono działanie hybrydowego niskonapięciowego ogranicznika prądu zwarciowego, składającego się z ultraszybkiego bezpiecznika, tranzystora mocy i warystora. W szczególności omówiono możliwości polepszenia jakości dostarczanej do odbiorców energii elektrycznej. Zastosowanie hybrydowego ogranicznika prądu znacznie ogranicza czasy trwania zapadów napięcia w systemie elektroenergetycznym. Obliczenia wykonano przy...
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Dynamic current-voltage characteristics of dielectrics with extremely low heat conductivity
PublicationZaprezentowano teoretyczny opis metody dynamicznych charakterystyk prądowo-napięciowych w przypadku znacznego gradientu temperatury w ciałach stałych o przewodności jonowej. Otrzymano rozwiązania równania transportu oraz równania charakterystyk, odnoszące się do ruchu cienkiej warstwy nośników ostałej grubości oraz warstwy rozszerzającej się. Podano także przybliżone wyrażenia opisujące czas przelotu nośników. Wyniki zweryfikowano...
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Magnetic field effects on emission and current in Alq3 - based electroluminescent devices.
PublicationW pracy zaobserwowano stromy wzrost natężenia elektroluminescencji w polach magnetycznych nie przekraczających 300mT. Efekt ten wywołany jest magnetyczno polową redukcją stopnia zmieszania singletowych i trypletowych par elektron dziura, wymuszonego przez nadsubtelne oddziaływanie spinów elektronowych z ich otoczeniem jądrowym.
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Effect of contactless hybrid current limiter on voltage dips in power system.
PublicationW referacie przedstawiono działanie hybrydowego niskonapięciowego ogranicznika prądu zwarciowego, składającego się z ultraszybkiego bezpiecznika, tranzystora mocy i warystora. W szczególności omówiono możliwości polepszenia jakości dostarczanej do odbiorców energii elektrycznej. Zastosowanie hybrydowego ogranicznika prądu znacznie ogranicza czasy trwania zapadów napięcia w systemie elektroenergetycznym. Obliczenia wykonano przy...
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Current mechanisms of IGP routing - expectations and possibilities in terms of QoS constraints
PublicationOd mechanizmów rutingu oczekuje się nowych możliwości z chwilą wprowadzenia wymagań QoS. W tym kontekście aktualne techniki rutingu IGP nie oferuja rozwiązań określających ścieżki gwarantujące QoS. W pracy przedstawiono propozycję rozszerzenia OSPF, które umożliwia uwzględnienie ograniczeń wynikających z QoS, gwarantując jednocześnie usługi na żądanym poziomie. To rozszerzenie zawiera zarówno liniowe jak i nieliniowe metryki. Wartości...
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Effect of temperature on dark current characteristics of silicon solar cells and diodes
PublicationW artykule przedstawiono analizę wpływu zmian temperatury na ciemne charakterystyki prądowo-napięciowe ogniw fotowoltaicznych i diod z monokrystalicznego krzemu. Badania eksperymentalne przeprowadzono w zakresie temperatur od 295 do 373 K. W celu wyznaczenia wartości rezystancji szeregowej wyznaczono szereg ciemnych charakterystyk I-U. Stwierdzono, że rezystancja szeregowa rośnie wraz ze wzrostem temperatury 0,65% /K i dlatego...
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Feedback Control of Doubly-Fed Generator Connected to Current Source Converter
PublicationDoubly-fed induction generator (DFIG) system supplied by current source converter (CSC) is considered in this article. The DFIG can work in two independent modes: AC grid connection and stand-alone mode. The DFIG is connected to the ac grid directly through its stator and the CSC links the rotor side. In this mode, the active and reactive powers of the DFIG must be controlled. This article proposes two control system structures...
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Requirements for Residual Current Devices Intended for Electric Vehicle Charging Systems
PublicationThe properties of residual current devices have been presented from the point of view of their ability to detect a specific shape of the residual current waveform. Moreover, the standard requirements relating to residual current protection used in electric vehicle charging installations have been pointed out. The operating characteristics of the IC-CPD and RDC-DD protections, which are intended for charging electric vehicles in...
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Current trends in the field of steganalysis and guidelines for constructions of new steganalysis schemes
PublicationThe paper concerns blind steganalysis techniques in the passive steganalysis scenario designed to detect the steganographic cover modification schemes. The goal is to investigate the state-of-art in the field of steganalysis, and, above all, to recognize current trends existing in this field and determine guidelines for constructions of new steganalysis schemes. The intended effects are to examine the possibilities for the development...
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Method of sacrificial anode dual transistor-driving in stray current field
PublicationIn order to control a magnesium anode in a stray current interference field, a dual transistor driving system has been proposed. It consisted of a combination of PNP and NPN transistors. Dual transistor driven system and direct anode to cathode connection were electrochemically tested in 3% NaCl solution. The dual transistor driven system increased the anode efficiency and reduced hydrogen evolution and the risk of embrittlement....
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Automated Diagnostics of Current Pick-Up Disturbances in Electric Traction Networks
PublicationThe present work defines the basic causes of bow disturbances of current pick-up, sets a task of establishing a system of automated control of bow disturbances at feeder zones of electric traction networks, proposes structural variants of the technical system implementation, describes the algorithm of detection of bow disturbances of current pick-up.
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Dead-Time Effect Compensation Based on Additional Phase Current Measurements
PublicationThis paper proposes a new method of dead-time effect compensation. The proposed solution is based on additional phase current measurements realized by analog-to-digital converters. These measurements are carried out at the time instants specified by a pulsewidth-modulation (PWM) strategy. This makes it possible to estimate inverter currents at the commutation instants and, finally, to estimate the voltage error caused by dead time. This...
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Comprehensive compensation of grid current distortion by shunt active power filters
PublicationThe paper presents a comprehensive approach to the compensation of grid current distortion in shunt active power filter systems. Four sources of current distortion are addressed: imperfect grid synchronization caused by the distortion in the grid voltages, time delays in the evaluation of grid voltages and computation of compensating currents, fluctuations of the dc bus voltage, and the distortion of inverter output voltages due...
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Application of ionic liquids in microextraction techniques: Current trends and future perspectives
PublicationIonic liquids (ILs) with their unique properties found so far numerous analytical applications. Among them ILs both in their liquid form and immobilized on the surface or within the pores of a solid support were successfully utilized in microextraction techniques. The scope of this review will cover a comprehensive summarizing of available literature data on selected properties of ILs playing a key role in analytical purposes,...
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Artificial-Hand Technology—Current State of Knowledge in Designing and Forecasting Changes
PublicationThe subject of human-hand versatility has been intensively investigated for many years. Emerging robotic constructions change continuously in order to mimic natural mechanisms as accurately as possible. Such an attitude is motivated by the demand for humanoid robots with sophisticated end effectors and highly biomimic prostheses. This paper provides wide analysis of more than 80 devices that have been created over the last 40 years....
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Current issues of functional safety and cybersecurity analysis of the industrial and critical infrastructures
PublicationThis article addresses some functional safety assessment procedures with cybersecurity aspects in critical industrial installations with regard to the functional safety requirements specified in standards IEC 61508 and IEC 61511. The functional safety management includes hazard identification, risk analysis and assessment, specification of overall safety requirements and definition of safety functions. Based on the risk assessment...