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Search results for: WAVELET TRANSFORMS
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Detection of inter-turn faults in transformer winding using the capacitor discharge method
PublicationThe paper presents results of an analysis of inter-turn fault effects on the voltage and current waveforms of a capacitor discharge through transformer windings. The research was conducted in the frame of the Facility of Antiproton and Ion Research project which goal is to build a new international accelerator facility that utilizes superconducting magnets. For the sake of electrical quality assurance of the superconducting magnet...
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Distribution Transformer with Multi-Zone Voltage Regulation for Smart Grid System Application
PublicationThe article presents four concepts of the multi-zone voltage regulation (MZVR) system. It is a combination of a distribution transformer with an on-load tap-changer, for step voltage regulation, and a power electronic converter, dimensioned for a fraction of MZVR power, realizing continuous voltage regulation, supplemented by a special switch, the so-called bypass. This allows voltage regulation at high resolution, wide range and...
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Improving sensitivity of residual current transformers to high frequency earth fault currents
PublicationFor protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when high frequency earth fault current occurs. Serious hazard of electrocution exists then. In order to detect such a current, it is necessary to modify parameters of residual current devices, especially the operating point of their current transformer. The authors proposed...
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Comparison of Transmission Capacities of Two Regulation Systems: Lateral and in-phase Control Transformers
PublicationThis paper presents a comparison of regulation capabilities of lateral and in-phase control transformers in a selected node of a power system. Their regulation capabilities are presented, as well as cross-system exchange options.
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Design of quarter-wave compact impedance transformers using coupled transmission lines
PublicationPrzedstawiono porównanie wyników symulacji jedno i wielosekcyjnych transformatorów impedancji budowanych w postaci struktur wykorzystujących idealnenie sprzężone linie transmisyjne, idealne sprzężone symetryczne linie transmisyjne oraz rzeczywiste sprzężone linie mikropaskowe. Pokazano, że możliwa jest konstrukcja transformatorów impedancji o bardzo dobrych parametrach technicznych wykorzystująca sprzężone linie mikropaskowe, pomimo...
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Smart MV/LV distribution transformer for Smart Grid with active prosumer participation
PublicationWraz z rozwojem sieci dystrybucyjnych i ich stopniowym przekształcaniem w inteligentne sieci typu Smart Grid będzie rosłoznaczenie i udział sterowanych układów przekształtnikowych mocy stosowanych jako interfejsy pomiędzy źródłami energii a sieciąoraz pomiędzy siecią a odbiorcami. W artykule rozwinięto koncepcję wymiany konwencjonalnych transformatorów dystrybucyjnych50 Hz na inteligentne transformatory dystrybucyjne. Zaproponowano...
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Method for Clustering of Brain Activity Data Derived from EEG Signals
PublicationA method for assessing separability of EEG signals associated with three classes of brain activity is proposed. The EEG signals are acquired from 23 subjects, gathered from a headset consisting of 14 electrodes. Data are processed by applying Discrete Wavelet Transform (DWT) for the signal analysis and an autoencoder neural network for the brain activity separation. Processing involves 74 wavelets from 3 DWT families: Coiflets,...
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Fourier transform infrared spectroscopic and theoretical study of water interactions with glycine and its N-methylated derivatives
PublicationZbadano hydratację glicyny i jej metylowych pochodnych: N-metyloglicyny (NMG), N,N-dimetyloglicyny (DMG) i N,N,N-trimetyloglicyny (TMG) przy wykorzystaniu spektroskopii FTIR, z zastosowaniem cząsteczki HDO jako sondy molekularnej. Ilościowa wersja metody widm różnicowych pozwoliła na wyizolowanie widma wody zaburzonej przez substancję rozpuszczoną. Wyniki widmowe zostały skonfrontowane z obliczeniami teoretycznymi w ramach teorii...
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A New Expression for the 3-D Dyadic FDTD-Compatible Green's Function Based on Multidimensional Z-Transform
PublicationIn this letter, a new analytic expression for the time-domain discrete Green's function (DGF) is derived for the 3-D finite-difference time-domain (FDTD) grid. The derivation employs the multidimensional Z-transform and the impulse response of the discretized scalar wave equation (i.e., scalar DGF). The derived DGF expression involves elementary functions only and requires the implementation of a single function in the multiple-precision...
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Application of the Fractional Fourier Transform for dispersion compensation in signals from a fiber-based Fabry-Perot interferometer
PublicationOptical methods of measurement do not require contact of a probe and the object under study, and thus have found use in a broad range of applications such as nondestructive testing (NDT), where noninvasive measurement is crucial. Measuring the refractive index of a material can give a valuable insight into its composition. Low‑coherence radiation sources enable measurement of the sample’s properties across a wide spectrum, while...
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The effect of current signal filtering method on the value of cutting power while sawing wood
PublicationThe goal of this work was to investigate an effect of various signal pre-processings on the outline of the electrical power curve and its influence on the measured cutting force estimation. Two signal processing methods were selected for the needs of the experiment, including digital filter and wavelet transform. The filter used was Butterworth, 3rd order band-stop with the cut-out band from 45 Hz to 55 Hz. The second approach...
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Seismic damage diagnosis in adjacent steel and RC MRFs considering pounding effects through improved wavelet-based damage-sensitive feature
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Seismic damage diagnosis in adjacent steel and RC MRFs considering pounding effects through improved wavelet-based damage-sensitive feature
PublicationThis paper aims to propose complex Morlet (cmorfb-fc) wavelet-based refined damage-sensitive feature (rDSF) as a new and more precise damage indicator to diagnose seismic damages in adjacent steel and Reinforced Concrete (RC) Moment Resisting Frames (MRFs) assuming pounding conditions using acceleration responses. The considered structures include 6- and 9-story steel and 4- and 8-story RC benchmark...
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Seismic damage diagnosis in adjacent steel and RC MRFs considering pounding effects through improved wavelet-based damage-sensitive feature
PublicationThis paper aims to propose complex Morlet (cmorfb-fc) wavelet-based refined damage-sensitive feature (rDSF) as a new and more precise damage indicator to diagnose seismic damages in adjacent steel and Reinforced Concrete (RC) Moment Resisting Frames (MRFs) assuming pounding conditions using acceleration responses. The considered structures include 6- and 9-story steel and 4- and 8-story RC benchmark MRFs that are assumed to have...
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Damage detection in turbine wind blades by vibration based methods
PublicationThe paper describes results of numerical simulation for damage localization in the composite coat of a wind turbine blade usingmodal parameters and a modern damage detection method (wavelet transform).
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Determination of Complex Permeability of Silicon Steel for Use in High-Frequency Modeling of Power Transformers
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A Combined TOPSIS and FA Based Strategic Analysis of Technical Condition of High Power Transformers
PublicationThe paper presents mathematical model { TOPSIS method, which was utilized on insulating state of distribution transformer to analyze and sensibility of individual measurements methods mutual comparison. We can uniquely determine the importance of these measurements methods with this mathematical appara- tus in these measurements methods in insulating state of transformers.
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Space-mapping-based design flow of miniaturized broadband matching transformer with perforated metallization
PublicationA fast design procedure of unconventional passive components has been presented and experimentally validated on the basis of a wideband microstrip four-section matching transformer (50:6 OHm). A classic impedance matching circuit has been miniaturized by means of compact microstrip resonant cells (CMRCs) leading to a considerable length reduction (34%) together with minor degradation in its performance. The spacemapping-based design...
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Recycling of Polyurethanes Containing Flame-Retardants and Polymer Waste Transformed into Flame-Retarded Polyurethanes
PublicationThe growing number of polyurethanes (PUs) produced every year has developed methods for their mechanical and chemical recycling which yield valuable products like substitutes for commercial polyols or flame-retardants. PUs can be produced in different shapes and forms (i.e., elastomers, flexible or rigid foams, coatings, etc.) using several different components (i.e., di- or polyisocyanates, ester- or ether-based polyols, low-molecular...
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Rapid multi-objective design optimization of miniaturized impedance transformer by Pareto front exploration
PublicationFast multi-objective optimization of compact impedance transformer is discussed. A set of alternative designs representing possible trade-offs between conflicting design criteria, i.e., electrical performance (here, wideband matching) and the structure size, is obtained through Pareto front exploration by means of surrogate-assisted methods.
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EM-Driven Multi-Objective Design of Impedance Transformers By Pareto Ranking Bisection Algorithm
PublicationIn the paper, the problem of fast multi-objective optimization of compact impedance matching transformers is addressed by utilizing a novel Pareto ranking bisection algorithm. It approximates the Pareto front by dividing line segments connecting the designs found in the previous iterations, and refining the obtained candidate solutions by means of poll-type search involving Pareto ranking. The final Pareto set is obtained using...
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A bisection‐based heuristic for rapid EM‐driven multiobjective design of compact impedance transformers
PublicationDesign of microwave structures is a multiobjective task where several conflicting requirements have to be considered at the same time. For contemporary circuits characterized by complex geometries, multiobjective optimization cannot be performed using standard population‐based algorithms due to high cost of electromagnetic (EM) evaluations. In this work, we propose a deterministic approach for fast EM‐driven multiobjective design...
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Application of splines and wavelets along with TIN decimation to 3D imagingof seafloor from multibeam sonar data
PublicationW pracy przedstawiono dwie metody reprezentacji danych batymetrycznych otrzymanych z pomiarów z użyciem sonaru wielowiązkowego. Reprezentacja przy pomocy funkcji sklejanych jest odpowiednia dla baz danych, podczas gdy reprezentacja z wykorzystaniem funkcji falkowych posiada dobre właściwości kompresyjne.
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The use of terrestrial laser scanning in monitoring and analyses of erosion phenomena in natural and anthropogenically transformed areas
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3-phase medium frequency transformer for a 100kW 1.2kV 20kHz Dual Active Bridge converter
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Simulation of the Remanence Influence on the Transient States of the Single-Phase Transformer Including Feedback Preisach Model
PublicationThis paper presents the results of the experimental and simulation investigation concerning the influence of remanence in the core of a single-phase transformer at the no-load transient state. Experimental studies consisted of the discharge of the capacitor through the primary winding at several different values of the residual magnetic flux. The paper presents a model of the transformer test system, taking into account the magnetic...
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Characterization of immobilized Escherichia coli cells transformed by β-galactosidase gene from Pyrococcus woesei
PublicationThermostable β-galactosidase from Escherichia coli transformant containing theenzyme gene from Pyrococcus woesei was immobilized on alginate gel.The benefits of using whole bacterial cells not only exclude expensive, laborious proteinisolation and purification but also stabilize enzymes by cytosol components. Increase inproductivity of enzyme can be achieved by cells permeabilization. To increase permeability ofcytoplasmic membrane...
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Selected aspects of traction transformer diagnosis based on analysis of power looses in windings and the iron core
PublicationW rozdziale przedstawiono metodę diagnostyki detekcji uszkodzeń wewnętrznych uzwojeń transformatora trakcyjnego oparta na analizie strat mocy rozpraszanej wewnątrz transformatora. Straty mocy są powiekszane o szereg czynników świadczacych o uszkodzeniu transformatora takich jak: zwarcia zwojowe, asymetria uzwojeń, relaksacja naprężeń na stykach połaczeń, uszkodzenie izolacji pomiedzy blachami rdzenia itp. Proponowana metoda dokonuje...
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Power Electronics Building Blocks for implementing Smart MV/LV Distribution Transformers for Smart Grid
PublicationWith an observed increase in the involvement of active consumers in activities aimed at improving energy efficiency and increasing interest in producing energy from renewable sources, there is a need for the development of new technologies enabling the distribution network operators to offer new services and functionalities. Smart MV/LV distribution transformers are characterized by a compact three-stage design, including an...
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Modification of the operating point of residual current transformers for high frequency earth fault currents detection
PublicationFor protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when earth fault current with high frequency components occurs. Serious hazard of electrocution exists then. One of the most important element of residual current devices is a residual current transformer with iron core. Tripping characteristic of residual current devices strictly...
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SiC-Based Power Electronic Traction Transformer (PETT) for 3 kV DC Rail Traction
PublicationThe design of rolling stock plays a key role in the attractiveness of the rail transport. Train design must strictly meet the requirements of rail operators to ensure high quality and cost-eective services. Semiconductor power devices made from silicon carbide (SiC) have reached a level of technology enabling their widespread use in traction power converters. SiC transistors oering energy savings, quieter operation, improved reliability...
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Modified Preisach model of hysteresis in multi air gap ferrite core medium frequency transformer
PublicationThis article presents the modified Preisach model of hysteresis for a 3-phase medium frequency transformer in a 100 kW dual active bridge converter. The transformer magnetic core is assembled out of ferrite I-cores, which results in multiple parasitic air gaps. For this transformer, the hysteresis loops were measured and parameters of the Preisach model were determined. The Preisach distribution function is approximated with a...
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On deterministic procedures for low-cost multi-objective design optimization of miniaturized impedance matching transformers
PublicationPurpose This paper aims to investigate deterministic strategies for low-cost multi-objective design optimization of compact microwave structures, specifically, impedance matching transformers. The considered methods involve surrogate modeling techniques and variable-fidelity electromagnetic (EM) simulations. In contrary to majority of conventional approaches, they do not rely on population-based metaheuristics, which permit lowering...
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3-phase medium frequency transformer for a 100kW 1.2kV 20kHz Dual Active Bridge converter
PublicationThe article presents a three-phase Medium Frequency Transformer being a part of a 100kW 1.2kV 20kHz Dual Active Bridge DC-DC converter. The transformer design is detailed focusing on winding and core power loss calculation. The high power three-phase MFT prototype is presented. The experimental results include the transformer impedance characteristics, no load test and three-phase DAB full load test waveforms
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Multi-transformer primary-side regulated flyback converter for supplying isolated IGBT and MOSFET drivers
PublicationThis paper presents primary-side voltage regulated multi-transformer quasi-resonant flyback converter (MTFC) for supplying isolated power switch drivers. The proposed topology offers distinct advantages over frequently used flyback converter possessing one high frequency transformer with isolated multiple outputs. Particularly, when a large number of separate dc supply units is required, then MTFC enables improved regular distribution...
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Surrogate modeling of impedance matching transformers by means of variable‐fidelity electromagnetic simulations and nested cokriging
PublicationAccurate performance evaluation of microwave components can be carried out using full‐wave electromagnetic (EM) simulation tools, routinely employed for circuit verification but also in the design process itself. Unfortunately, the computational cost of EM‐driven design may be high. This is especially pertinent to tasks entailing considerable number of simulations (eg, parametric optimization, statistical analysis). A possible...
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Nieliniowy model matematyczny transformatora trójfazowego = Non-linear mathematical model of a three-phase transformer
PublicationPrzedstawiono model transformatora trójfazowego o rdzeniu trójkolumnowym, który zawiera układ rów-nań opisujących obwód magnetyczny oraz oddzielnie układ równań obwodu elektrycznego. Wydzielenie re-luktancji elementów rdzenia umożliwia uwzględnienie zmian względnej przenikalności magnetycznej w funkcji bieżącej wartości strumienia w rdzeniu. Re-luktancje odpowiadające strumieniom rozproszenia obliczono wg zasad klasycznych. Funkcję...
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Fourier-transform infrared spectroscopy (FTIR) spectra of bulk boron and borophene flakes
Open Research DataThese data contain Fourier-transform infrared spectroscopy (FTIR) spectra of bulk boron and borophene flakes obtained during ball milling (450 rpm, 6 h, 1 g). Spectra were acquired to investigate the chemical bonds and functional groups on the surface of the pristine boron and borophene flakes.
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Development of fragility curves in adjacent steel moment-resisting frames considering pounding effects through improved wavelet-based refined damage-sensitive feature
PublicationFragility curves present useful information related to earthquake-induced probability assessment of steel moment-resisting frames (MRFs) and determine the probability of the damage exceedance at different floor levels of MRFs. The review of the literature shows that most of the previous studies dealing with the fragility curves were based on conventional measures, such as spectral acceleration at the first mode period, peak...
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Measurements of no-load and short-circuit parameters of power transformers with taps
Open Research Data1) The Laboratory LINTE^2 is a large research infrastructure operated by the Faculty of Electrical and Control Engineering at Gdańsk University of Technology, to be found in Gdańsk, Poland (54.3690 N, 18.6130 E).
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Assessment of the structural evolution of polyimide-derived carbons obtained by phosphoric acid activation using Fourier transform infrared and Raman spectroscopy
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Fast Fourier Transform detection and reduction of high-frequency errors from the results of surface topography profile measurements of honed textures
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Improving Accuracy of Respiratory Rate Estimation by Restoring High Resolution Features With Transformers and Recursive Convolutional Models
PublicationNon-contact evaluation of vital signs has been becoming increasingly important, especially in light of the COVID- 19 pandemic, which is causing the whole world to examine people’s interactions in public places at a scale never seen before. However, evaluating one’s vital signs can be a relatively complex procedure, which requires both time and physical contact between examiner and examinee. These re- quirements limit the number...
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Activity coordination of capacitor banks and power transformer controllers in order to reduce power losses in the MV grid
PublicationOne of the main issues related to the optimization of the MV (middle voltage) network is to reduce losses of active and reactive power. Lower losses of active and reactive power give not only economic advantage, but also improvement of energy quality. The object of regulation that can be used for these purposes are transformer with On-Load Tap Changer and capacitor's banks. This paper presents results of analysis of the possibility...
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Experimental verification and comparison of mode shape-based damage detection methods
PublicationThis paper presents experimental verification and comparison of damage detection methods based on changes in mode shapes such as: mode shape curvature (MSC), modal assurance criterion (MAC), strain energy (SE), modified Laplacian operator (MLO), generalized fractal dimension (GFD) and Wavelet Transform (WT).
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FTIR (Fourier-transform infrared spectroscopy) spectra of titanium dioxide coated nickel foams.
Open Research DataThis dataset contains FTIR spectra recorded on a JASCO 4200 spectrometer of nickel foams coated with titanium dioxide after heating at 400, 500 and 600 C and after photocatalytic process with NOx.
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Marek Adamowicz dr hab. inż.
PeopleStopień naukowy doktora uzyskał w 2008 r. na Wydziale Elektrotechniki i Automatyki Politechniki Gdańskiej. W latach 2005 – 2011 pracował na Akademii Morskiej w Gdyni. W 2010 r. jako laureat programu NCBR LIDER wybrał Wydział Elektrotechniki i Automatyki Politechniki Gdańskiej jako jednostkę realizującą swój projekt z zakresu szerokopasmowych przyrządów półprzewodnikowych i ich zastosowań w elektrowniach wiatrowych. Od 2011 roku...
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In situ study of a composition of outlet gases from biogas fuelled Solid Oxide Fuel Cell performed by the Fourier Transform Infrared Spectroscopy
PublicationThe purpose of this study was to develop a method and software based on the Fourier Transform Infrared Spectroscopy for the in-situ, quantitative analysis of the composition of outlet gases from Solid Oxide Fuel Cell (SOFC). The calibration procedure performed at the beginning of the experiment indicated a polynomial dependence between the concentration of a calibrating gas (CO, CO2, CH4) and the corresponding integrated absorbance in...
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NPC assessment in insulated DC/DC converter topologies using SiC MOSFETs for Power Electronic Traction Transformer
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Measurements and calculation of self inductance of testing coils used in physical transformer model construction and its frequency analysis
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