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Search results for: HARMONICS SUPPRESSION
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A CMRC-based compact rat-race coupler with harmonic suppression
PublicationIn this paper, an eective miniaturization technique exploiting compact microstrip resonant cells has been discussed and experimentally validated on the basis of a 3-dB microstrip rat-race coupler. The application of the method proposed has resulted in 91 % circuit area reduction in comparison to a conventional rat-race coupler. Experimental results show good agreement with theoretical characteristics, as well as an additional eect,...
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Design of a Patch Power Divider with Simple Structure and Ultra-Broadband Harmonics Suppression
PublicationThis paper introduces a simple H-shaped patch Wilkinson power divider (WPD), which provides ultra wide harmonics suppression band. The presented WPD designed at 1.8 GHz, and exhibits good performance at the operating bandwidth. In the proposed divider structure, two simple patch low-pass filters (LPFs) are employed at each branch, and three open ended stubs are added at each port. The proposed divider, implemented using the aforementioned...
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Design of a compact planar transmission line for miniaturized rat-race coupler with harmonics suppression
PublicationThis paper presents an elegant yet straightforward design procedure for a compact rat-race coupler (RRC) with an extended harmonic suppression. The coupler’s conventional λ/4 transmission lines (TLs) are replaced by a specialized TL that offers significant size reduction and harmonic elimination capabilities in the proposed approach. The design procedure is verified through the theoretical, circuit, and electromagnetic (EM) analyses,...
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Suppression of Supply Current Harmonics of 18-Pulse Diode Rectifier by Series Active Power Filter with LC Coupling
PublicationThe reported research aims at improving the quality of three-phase rectifier supply currents. An effective method consists of adding properly formed booster voltages to the fundamental supply voltages using a series active filter. In the proposed solution, the booster voltages are generated by three single-phase systems consisting of inverters, LC filters, and single-phase transformers. The application of LC couplings ensures low...
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СИЛОВОЙ ПРЕОБРАЗОВАТЕЛЬ С АКТИВНЫМ ПОДАВЛЕНИЕМ ВЫСШИХ ГАРМОНИК ДЛЯ СИСТЕМ ЭЛЕКТРОСНАБЖЕНИЯ ЛЕТАТЕЛЬНЫХ АППАРАТОВ (Power converter with active suppression of higher harmonics for aircraft power supply systems)
PublicationПредставлены два алгоритма активной фильтрации для силового преобразователя с активным подавлением высших гармоник. Первый алгоритм основан на дискретном преобразовании Фурье: посредством синтезированной системы управления инвертированные измеренные высшие гармоники напряжения поступают на вход инвертора. Второй метод управления основан на алгоритме с использованием принципов самообучения, что значительно снижает потребность в...
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Optimization of active circuits for substrate noise suppression
PublicationZakłócenia generowane przez szybkie podukłady cyfrowe w mieszanych systemach analogowo-cyfrowych realizowanych na wspólnym podłożu stają się dużym problemem. W pracy zaproponowano metodę optymalizacji aktywnych układów tłumienia zakłóceń. Zilustrowano skuteczność działania metody na wybranym układzie i uzyskano ponad 9 dB poprawę tłumienia zakłóceń na częstotliwości 1GHz w porównaniu do znanych rozwiązań.
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Mutual Clutter Suppression Techniques for FM Sonars
PublicationThe article presents methods that help in the elimination of mutual clutter as well as the consequences of two FM sounding signal sonars operating in the same body of water and frequency band. An in-depth analysis of mutual clutter was carried out. The effects of sounding signal differentiation were determined, as was the Doppler effect on mutual clutter suppression. One of the methods analysed is of particular interest in a situation...
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Active Suppression of Nonstationary Narrowband Acoustic Disturbances
PublicationIn this chapter, a new approach to active narrowband noise control is presented. Narrowband acoustic noise may be generated, among others, by rotating parts of electro-mechanical devices, such as motors, turbines, compressors, or fans. Active noise control involves the generation of “antinoise”, i.e., the generation of a sound that has the same amplitude, but the opposite phase, as the unwanted noise, which causes them to interfere...
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Narrowband interference suppression in IEEE 802.15.4a ultrawideband receiver
PublicationW referacie przedstawiono metodę redukcji wpływu silnych sygnałów wąskopasmowych na jakość transmisji ultraszerokopasmowej w standardzie IEEE 802.15.4a poprzez modyfikację sekwencji impulsów w odbiorniku korelacyjnym. Opisano strukturę rozpatrywanego odbiornika i sposób tworzenia zmodyfikowanych sekwencji wzorcowych, a także przedstawiono wyniki symulacji komputerowych jakości pracy łącza UWB w obecności zakłóceń o charakterze...
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Field-induced suppression of charge density wave in GdNiC2
PublicationWe report the specific heat, magnetic, magnetotransport, and galvanomagnetic properties of polycrystalline GdNiC 2 . In the intermediate temperature region above T N = 20 K, we observe large negative magnetoresistance due to Zeeman splitting of the electronic bands and partial destruction of a charge density wave ground state. Our magnetoresistance and Hall measurements show that at low temperatures a magnetic field-induced transformation from...
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Highly porous nanoberyllium for X-ray beam speckle suppression
PublicationThe speckle suppressor device containing highly porous nanoberyllium is proposed for manipulating with the spatial coherence length and removing undesirable speckle structure during the imaging experiments. We report a special device called the speckle suppressor, which contains the highly porous nanoberyllium plate, compacted from both sides by two beryllium windows. By insertion the speckle suppressor in the X-ray beam it allows...
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The problem of “spectrum leakage” in the measurement of harmonics
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S-Shaped Suppression of the Superconducting Transition Temperature in Cu-Intercalated NbSe2
Publication2H-NbSe2 is the prototype and most frequently studied of the well-known transition metal dichalcogenide (TMDC) superconductors. As 2H-NbSe2 is widely acknowledged as a conventional superconductor, its transition temperature to the superconducting state (Tc) is 7.3 K, a Tc that is substantially higher than those seen for the majority of TMDCs, where Tc values between 2 and 4 K are the norm. Here we report the intercalation of Cu...
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High Frequency Harmonics Emission in Smart Grids
PublicationPulse-width modulated rectifiers are nowadays commonly used for AC to DC power conversion. PWM rectification technology is very effective and allows for bidirectional power flow with the possibility of power factor improvement and low-order harmonic emission limitation. Unfortunately, employed PWM boost topology results with generation of input current harmonic distortions in a frequency range tightly correlated to modulation frequency....
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Suppression of distortions in signals received from Doppler sensor for vehicle speed measurement
PublicationDoppler sensors are commonly used for movement detection and speed measurement. However, electromagnetic interference and imperfections in sensor construction result in degradation of the signal to noise ratio. As a result, detection of signals reflected from moving objects becomes problematic. The paper proposes an algorithm for reduction of distortions and noise in the signal received from a simple, dual-channel type of a Doppler...
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Voltage Harmonics Measuring Issues in Medium Voltage Systems
PublicationW rozdziale przedstawiono zagadnienia związane z dokładnością pomiarów zniekształceń harmonicznych napięcia z wykorzystaniem przekładników napięciowych w sieciach średnich napięć.
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Application of the Harmonic Balance Method for Spatial Harmonic Interactions Analysis in Axial Flux PM Generators
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Feature-Based Characterisation of Turned Surface Topography with Suppression of High-Frequency Measurement Errors
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Suppression of deleterious effects of free silanols in liquid chromatography by imidazolium tetrafluoroborate ionic liquids
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Selection of C-Type Filters for Reactive Power Compensation and Filtration of Higher Harmonics Injected into the Transmission System by Arc Furnaces
PublicationThis article presents a method for selecting the elements of a C-type filter working with a conventional LC-type filter for compensating reactive power and filtering out higher harmonics generated by arc furnaces and ladle furnaces. The study was conducted in a steel mill supplied by a 110 kV transmission system, where higher harmonic currents and nonlinear loads were measured. A series of computer simulations were performed under...
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Harmonions Coloring of Graphs.
PublicationProblem kolorowania grafów jest motywowany radionawigacją lotniczą, kompresją obrazów i in. W rozdziale podano podstawowe fakty dotyczące tego modelu kolorowania, a wsród nich dolne i górne oszacowania na liczbę harmoniczną i algorytm o złożoności 0 (mm3) dający bardzo dobre pokolorowania przybliżone.
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Detection and compensation of torque harmonics in drive with induction motor and gear
PublicationUkład mechaniczny przeniesienia napędu jest stosowany w większości elektrycznych układów napędowych. Właściwości przekładni mechanicznej powodują występowanie drgań moemntu w układzie. Analiza tych drgań, mierzonych np. za pomoca akcelerometrów, umozliwia detekcję uszkodzeń przekładni. Z uwiagi na trudności pomiatrowe dąży się jednak do eleminacji układów pomiarowych drgań przez zastąpienie ich metodami obliczeniowymi. Znając...
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Harmonics produced by traction substations – computer modelling and experimental verification
PublicationVoltage and current harmonics have a detrimental effect on the components of a power system. Current harmonics may result in the overload and damage to power transformers. Voltage harmonics may result in, for example, damage to capacitor banks used to compensate reactive power. Devices which contribute to both current and voltage distortion include traction rectifiers. This paper presents results of the computer investigation of...
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Compressive Sensing Approach to Harmonics Detection in the Ship Electrical Network
PublicationThe contribution of this paper is to show the opportunities for using the compressive sensing (CS) technique for detecting harmonics in a frequency sparse signal. The signal in a ship’s electrical network, polluted by harmonic distortions, can be modeled as a superposition of a small number of sinusoids and the discrete Fourier transform (DFT) basis forms its sparse domain. According to the theory of CS, a signal may be reconstructed...
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Voltage Harmonics Transfer through Medium Voltage Instrument Transformers
PublicationVoltage transformers are widely used in power quality monitoring systems in medium and high voltage grids. This paper presents accuracy problems related to voltage harmonics transfer through instrument transformers. A simplified lumped-parameters wideband circuit model of the voltage transformer is proposed and verified by simulation and experimental investigations. A number of voltage transformers have been tested in the frequency...
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Enhancement of Thermal Stability, Conductivity and Smoke Suppression of Polyethylene Composites with Exfoliated MoS2 Functionalized with Magnetite
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Polish version of the White Bear Suppression Inventory (WBSI) by Wegner and Zanakos: factor analysis and reliability
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Application of inserts for suppression of coupled dynamic-acoustic effects during confined granular flow in silos
PublicationArtykuł omawia sposoby redukcji efektów dynamiczno-akustycznych w silosach. Do redukcji zastosowano różne wkładki. Zbadano wpływ kształtu i liczby wkładek w doświadczeniach. Na podstawie wyników doświadczalnych opracowano metodę redukcji efektów dynamiczno-akustycznych w dużych stalowych silosach.
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Myeloid-derived suppressor cells: a double-edged sword?
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Harmonic Analysis Of Electrochemical and Corrosion Systems - A Review
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Fermionized Dipolar Bosons Trapped in a Harmonic Trap
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Corrosion monitoring by harmonic analysis in aqueous environments
PublicationThis paper presents tests concerning the rate of corrosion in non-alloy steel (type S235JR) in an aqueous environment, with an additive of sodium chloride by means of polarization resistance measurements and harmonic analysis. The tests have been carried out for steel samples exposed to the testing environment for six weeks, in order to obtain a constant rate of corrosion in the function of time. The measurements have aimed at...
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Application of harmonic techniques to evaluation of pitting corrosion
PublicationPrzedstawiono próbę zastosowania metod zmiennoprądowych do oceny podatności na korozję wżerową stali stopowych. Na sygnał stałoprądowy nałożono sinusoidę o częstotliwości 10 Hz. Dzięki jednoczesnej, cyfrowej rejestracji sygnału pobudzenia i odpowiedzi układu badanego otrzymano ciągłe zmiany modułu impedancji i modułu pojemności w trakcie klasycznej cyklicznej polaryzacji. Na podstawie jednego eksperymentu istnieje możliwość wyznaczenia...
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The effect of earth fault current harmonics on tripping of residual current devices
PublicationSzerokie zastosowanie przekształtników, a w szczególności przemienników częstotliwości sprawia, że wyłączniki różnicowoprądowe znajdują się w obwodach, w których może płynąć odkształcony prąd ziemnozwarciowy. Prąd ziemnozwarciowy w obwodach z przemiennikami częstotliwości zawiera harmoniczne, których rząd głównie zależy od częstotliwości PWM. Odkształcony prąd wpływa na poprawne wyzwalanie wyłączników różnicowoprądowych. W artykule...
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Slot harmonics in cage motors due to saturation of a main magnetic circuit
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Enhancing capabilities of Atomic Force Microscopy by tip motion harmonics analysis
PublicationMotion of a tip used in an atomic force microscope can be described by the Lennard-Jones potential, approximated by the van der Waals force in a long-range interaction. Here we present a general framework of approximation of the tip motion by adding three terms of Taylor series what results in non-zero harmonics in an output signal. We have worked out a measurement system which allows recording of an excitation tip signal and its...
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Higher harmonics produced by traction substations – computer modelling and experimental verification
PublicationVoltage and current harmonics have a detrimental effect on the components of a power system. Current harmonics may result in the overload and damage to power transformers, although the rms value of load current does not exceed their current-carrying capacity. Voltage harmonics may result in, for example, damage to capacitor banks used to compensate reactive power. Devices which contribute to both current and voltage distortion...
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Suppression of the High-Frequency Errors in Surface Topography Measurements Based on Comparison of Various Spline Filtering Methods
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DDLMS PCR double digestion Ligation Mediated Suppression PCR - a new technique for bacterial specific differentiation
PublicationA new diagnostic kit for K. oxytoca specific differentiation based on ddLMS PCR (ang. double digest ligation Mediated PCR) technique is shown. As a species-specific DNA fragment pehX gene, encoding the enzyme polygalactouronase, was chosen. The genome sequence of K. oxytoca is digested with two endonucleases: AclI and BclI which cut DNA before and after pehX gene. The polymorphic DNA fragments are ligated with AclI-end-specific...
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Testing sensitivity of A-type residual current devices to earth fault currents with harmonics
PublicationIn many applications, modern current-using equipment utilizes power electronic converters to control the consumed power and to adjust the motor speed. Such equipment is used both in industrial and domestic installations. A characteristic feature of the converters is producing distorted earth fault currents, which contain a wide spectrum of harmonics, including high-order harmonics. Nowadays, protection against electric shock in...
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Higher harmonics of converter currents in energy conversion system of small water plants
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Atomic Force Microscope data post-processing algorithm for higher harmonics imaging
PublicationPrevious works have proved that higher harmonics topography imaging using atomic force microscope (AFM) can significantly enhanced its measurement capabilities. Integrated tools dedicated to most of microscopes allow to visualize the investigated surface only by one selected harmonic. Because of the different characteristics of a sample, scanning tip and the environment, appropriate harmonic selection is time consuming and requires...
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High Frequency Harmonics Emission of Modern Power Electronic AC-DC Converters
PublicationModern AC/DC converters with bidirectional power flow employing PWM boost topology generate harmonic distortions of input current in relatively high frequency range tightly related to modulation carrier frequency. These frequencies and its multiples in typical applications are usually located in frequency range from single up to several of kHz. Increased harmonic emission in this frequency range can easily and harmfully influence...
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Higher-order spectra for harmonics detection in nonlinear systems at presence of Gaussian noise.
PublicationPrzedstawiono metodę wykrywania harmonicznych w ukladach nieliniowych za pomocą funkcji bispektrum. Przebadano skuteczność proponowanej metody w porównaniu z metodą wykorzystującą gęstość widmową mocy. Badania przeprowadzono dla sygnałów będących sumą sygnału harmonicznego i realizacji szumu białego.
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Corrosion process monitoring by AFM higher harmonic imaging
PublicationThe atomic force microscope (AFM) was invented in 1986 as an alternative to the scanning tunnelling microscope, which cannot be used in studies of non-conductive materials. Today the AFM is a powerful, versatile and fundamental tool for visualizing and studying the morphology of material surfaces. Moreover, additional information for some materials can be recovered by analysing the AFM's higher cantilever modes when the cantilever...
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The application of Gabor transformation in the harmonic analysis of corrosion processes
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Frequency dispersion of harmonic components of the current of an electrode process
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Fundamental-harmonic impedance of first-order electrode reactions
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Quantum Correlations of a Few Bosons within a Harmonic Trap
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Dependence of harmonic generation on primary wave pressure distribution
PublicationPraca dotyczy numerycznego badania zagadnienia wytwarzania harmonicznych ciśnienia podczas rozchodzenia się fal o skończonej amplitudzie, promieniowanych przez źródła kołowe o różnych rozkładach. Model matematyczny zbudowano w oparciu o równanie KZK. Do numerycznego rozwiązania problemu zastosowano metodę bilansu harmonicznych i metodę różnic skończonych. Analizowano zmiany składowych harmonicznych ciśnienia w obrębie wiązki akustycznej....