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Search results for: frequency-dependent coupling
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Hysteresis modelling of a medium frequency single-phase transformer
PublicationThe article describes a feedback Preisach hysteresis model equivalent circuit implementation of a medium frequency single-phase transformer being a part of a high power and high efficiency DC-DC converter. The macroscopic models of magnetic hysteresis are introduced and the feedback Preisach model is selected for further analysis. The hysteresis model is developed for a prototype transformer and the hysteresis loops are compared...
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Mechanism of reaction of RNA-dependent RNA polymerase from SARS-CoV-2
PublicationWe combine molecular dynamics, statistical mechanics, and hybrid quantum mechanics/molecular mechanics simulations to describe mechanistically the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA-dependent RNA polymerase (RdRp). Our study analyzes the binding mode of both natural triphosphate substrates as well as remdesivir triphosphate (the active form of drug), which is bound preferentially over ATP by RdRp while...
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Tripping of F-type RCDs for High-Frequency Residual Currents
PublicationResidual current devices (RCDs) are apparatus commonly used for protection against electric shock in low-voltage electrical installations. They protect people in the case of an earth fault or even in the case of direct contact with the live parts. However, to be effective protective devices, RCDs have to detect residual currents of various waveform shapes which appear in modern electrical installations. For this purpose, RCDs...
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Tripping of F-type RCDs for high-frequency residual currents
PublicationResidual current devices (RCDs) are apparatus commonly used for protection against electric shock in low-voltage electrical installations. They protect people in the case of an earth fault or even in the case of direct contact with the live parts. However, to be effective protective devices, RCDs have to detect residual currents of various waveform shapes which appear in modern electrical installations. For this purpose, RCDs are...
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A Compact Basis for Reliable Fast Frequency Sweep via the Reduced-Basis Method
PublicationA reliable reduced-order model (ROM) for fast frequency sweep in time-harmonic Maxwell’s equations by means of the reduced-basis method is detailed. Taking frequency as a parameter, the electromagnetic field in microwave circuits does not arbitrarily vary as frequency changes, but evolves on a very low-dimensional manifold. Approximating this low-dimensional manifold by a low dimension subspace, namely, reduced-basis space, gives...
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A fast time-frequency multi-window analysis using a tuning directional kernel
PublicationIn this paper, a novel approach for time-frequency analysis and detection, based on the chirplet transform and dedicated to non-stationary as well as multi-component signals, is presented. Its main purpose is the estimation of spectral energy, instantaneous frequency (IF), spectral delay (SD), and chirp rate (CR) with a high time-frequency resolution (separation ability) achieved by adaptive fitting of the transform kernel. We...
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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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Throughput-Coverage Characteristics for Soft and Partial Frequency Reuse in the LTE Downlink
PublicationThe paper presents results of simulation and evaluation of throughput-coverage characteristics for the OFDMA-based LTE network with Soft Frequency Reuse or Partial Frequency Reuse. Firstly, simulation results of throughput characteristics for a single user connection are presented, which allow the evaluation of the stability and availability of bit rate achieved in different areas of a cell. Secondly, the capacity characteristics...
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Speech formant frequency and pitch estimation using instantaneous complex frequency
PublicationW pracy opisany został algorytm estymacji częstotliwości podstawowej oraz częstotliwości środkowych i pasm formantów mowy z wykorzystaniem zespolonej pulsacji chwilowej. W artykule przedstawiono również wyniki działania algorytmu dla polskich samogłosek.
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Determination of Mathematical Model Parameters of a Medium Frequency Transformer
PublicationThe paper presents the results of experimental studies of the medium frequency transformer. The object of the research was a prototype of a single-phase transformer with a core made of ferrite I-core elements and windings made of Litz conductors. The research was carried out to determine the parameters of the transformer's mathematical model. The scope of the tests included determining the magnetic hysteresis loop and measuring...
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Bearing estimation using double frequency reassignment for a linear passive array
PublicationThe paper demonstrates the use of frequency reassignment for bearing estimation. For this task, signals derived from a linear equispaced passive array are used. The presented method makes use of Fourier transformation based spatial spectrum estimation. It is further developed through the application of two-dimensional reassignment, which leads to obtaining highly concentrated energy distributions in the joint frequency-angle domain...
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CFD COUPLING OF VOF MODEL WITH ARRHENIUS EQUATION FOR ANALYSIS OF LASER-INDUCED THERMAL DEACTIVATION OF E. COLI
PublicationUnderstanding bacterial deactivation at the micro-scale, particularly with E. coli, is crucial for advancing microbiology and has promising applications in biomedical research. In this research contribution, we investigate the thermal inactivation of E. coli bacteria using gold nanoparticles irradiated by a green 1-W laser within a microfluidic chamber. The microfluidic device comprises a fluidic chamber filled with a thin film...
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Low frequency nois of supecapacitor
Open Research DataDataset contains results of low frequency noise observation during discharge of commercially available supercapacitor, type DRL 2.7V 10F, with a nominal capacitance 10 F and a nominal voltage 2.7 V. Supercapacitor was charged to various voltages and discharged through a resistor. In the experiment the 50 Ohm and 200 Ohm resistors were used. The supercapacitor...
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Editorial for the special issue on advances in forward and inverse surrogate modeling for high-frequency design
PublicationThe design of modern‐day high‐frequency devices and circuits, including microwave/RF, antenna and photonic components, historically has relied on full‐wave electromagnetic (EM) simulation tools. Initially used for design verification, EM simulations are nowadays used in the design process itself, for example, for finding optimum values of geometry and/or material parameters of the structures of interest. In a growing number of...
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Generalized adaptive notch filters with frequency debiasing for tracking of polynomial phase systems
PublicationGeneralized adaptive notch filters are used for identification/tracking of quasi-periodically varying dynamic systems and can be considered an extension, to the system case, of classical adaptive notch filters. For general patterns of frequency variation the generalized adaptive notch filtering algorithms yield biased frequency estimates. We show that when system frequencies change slowly in a smooth way, the estimation bias can...
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Frequency-Based Regularization for Improved Reliability Optimization of Antenna Structures
PublicationThe paper proposes a modified formulation of antenna parameter tuning problem. The main ingredient of the presented approach is a frequency-based regularization. It allows for smoothening the functional landscape of the assumed cost function, defined to encode the prescribed design specifications. The regularization is implemented as a special penalty term complementing the primary objective and enforcing the alignment of the antenna...
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Fast surrogate-assisted frequency scaling of planar antennas with circular polarisation
PublicationIn this work, the problem of computationally efficient frequency scaling (re-design) of circular polarisation antennas is addressed using surrogate-assisted techniques. The task is challenging and requires the identification of the optimum geometry parameters to enable the operation of the re-designed structure at a selected (required) centre frequency. This involves handling several performance figures such as the antenna gain,...
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Sympathetic neural responses to smoking are age dependent
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Craving sensation in the assessment of alcohol-dependent persons
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Polarization-dependent optical absorption in phosphorene flakes
PublicationThe interest of 2D materials is constantly increasing because of their very attractive mechanical, electrical and optical parameters. They have been used in many applications, e.g. photodetectors, sensors, modulators, insulators. One of the recently discovered 2D materials is phosphorene. In contrast to graphene, phosphorene has a direct bandgap tuned by numbers of layers in the 2D structure. The phosphorene flakes are strongly...
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Cluster-Dependent Feature Selection for the RBF Networks
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Low frequency nois of supecapacitor
Open Research DataDataset contains noise measurement results on prototype electrochemical double layer capacitor. The measurement procedure is described in https://dx.doi.org/10.1515/mms-2017-0059.
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Frequency response spectra applied to assess efficiency of the training techniques
PublicationThe purpose of the research is to assess the increase of the muscle strength and power. Movement of the human body when the moving one impacts a stationary or moving body is taken under consideration. The waveform produced by an impact is transformed into frequency domain. The acceleration record is transformed as a complex spectrum, by the use of a Discrete Fourier Transformation. In this paper the applications of the discrete...
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Shipping Low Frequency Noise and Its Propagation in Shallow Water
PublicationOne of the most significant factor influencing acoustical climate of the sea is underwater noise generated by moving ships. If the considered sea area has features of the shallow water, namely the wave frequency fulfils relation f < 10c/h, where c denotes phase speed of sound, and h is depths of the sea, then in certain distance from the wave source specific image of sound pressure distribution in the mean of wave modes appears....
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Analytical solution of non-stationary heat conduction problem for two sliding layers with time-dependent friction conditions
PublicationIn this article we conduct an overview of various types of thermal contact conditions at the sliding interface. We formulate a problem of non-stationary heat conduction in two sliding layers with generalized thermal contact conditions allowing for dependence of the heat-generation coefficient and contact heat transfer coefficient on time. We then derive an analytical solution of the problem by constructing a special coordinate...
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Strong-coupling character of superconducting phase in compressed selenium hydride
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Superstable magnetic nanoreactors with high efficiency for Suzuki-coupling reactions
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Pressure dependence of electron-phonon coupling inCe3+-dopedGd3Sc2Al3O12garnet crystals
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Predictive control of active filter system with LCL coupling circuit
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Coupling coefficients for the space group of the hexagonal close-packed structure
PublicationWe have computed the Clebsch-Gordan coefficients of the representations for the space group of the hexagonal close-packed structure for the points:V, A, H, K, L, M. We enumerate all arms of the wave vector stars and all wave vector selection rules.
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Nitrofurazone Removal from Water Enhanced by Coupling Photocatalysis and Biodegradation
Publication(1) Background: Environmental contamination with antibiotics is particularly serious because the usual methods used in wastewater treatment plants turn out to be insufficient or ineffective. An interesting idea is to support natural biodegradation processes with physicochemical methods as well as with bioaugmentation with efficient microbial degraders. Hence, the aim of our study is evaluation of the effectiveness of different...
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Eigenvalue approach to synthesis of prototype filters with source/load coupling
PublicationArtykuł przedstawia nową, szybko zbieżną, technikę syntezy macierzy sprzężeń filtrów o charaktrystyce Czebyszewa. Synteza opiera się na zastosowaniu metody najmniejszych kwadratów w odniesieniu do wartości własnych macierzy sprzężeń oraz jej podmacierzy.
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Multimodal coupling matrix for an array of rectangular slots on conducting cylinder
PublicationArtykuł prezentuje metodę wyznaczania sprzężeń wzajemnych pomiędzy aperturami promieniującymi położonymi na przewodzącym cylindrze. Pokazano sposób wyznaczania wielorodzajowej macierzy rozproszenia reprezentującej sprzężenia własne i wzajemne w badanej strukturze.
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Coupling coefficients for the space group of the hexagonal close-packed structure
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Local electrochemical impedance spectroscopy in dynamic mode of galvanic coupling
PublicationA novel method that combines local electrochemical impedance spectroscopy and mapping in dynamicmode is proposed. Method was validated over two galvanic couplings, namely zinc/copper and cad-mium/copper. Impedance spectrum response for all measuring points was obtained by means ofsimultaneous implementation of selected range of frequencies. Proposed method allows the measure-ment in a more time-efficient manner, at the same time...
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Identification of quasi-periodically varying systems with quasi-linear frequency changes
PublicationThe problem of identification of linear quasi-periodically varying systems is considered. This problem can be solved using generalized adaptive notch filtering (GANF) algorithms. It is shown that accuracy of system parameter estimation can be increased if the results obtained from GANF are further processed using a cascade of appropriately designed filters. The resulting generalized adaptive notch smoothing (GANS) algorithms can...
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Improvement of Fingerprinting Method based on Hill Cipher by using Frequency Domain
PublicationThe main goal of this paper is to present the advantages of a digital fingerprinting in a frequency domain over a pixel domain, in case of VoD services (Video on Demand). The paper presents basic issues of a multimedia data protection by digital fingerprinting. It also describes threats to embedded fingerprints from both collusion attacks and from a transmission itself. Possible solution was presented on the example of the DCT...
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Periodic Properties of 1D FE Discrete Models in High Frequency Dynamics
PublicationFinite element discrete models of various engineering 1D structures may be considered as structures of certain periodic characteristics. The source of this periodicity comes from the discontinuity of stress/strain field between the elements. This behaviour remains unnoticeable, when low frequency dynamics of these structures is investigated. At high frequency regimes, however, its influence may be strong enough to dominate calculated...
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Design of Frequency-Reconfigurable Branch-Line Crossover Using Rectangular Dielectric Channels
PublicationThis paper presents an efficient yet straightforward passive reconfiguration technique to tune the operating frequency of a branch-line crossover (BLCO). The underlying principle is to fill rectangular dielectric channels (RDCs) prepared beforehand with either air or materials of different relative permittivity. Two configurations (one RDC and three RDCs in each arm) of the branch-line crossover are employed to estimate the tunability...
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Modelling and analysis of medium frequency transformers for power converters
PublicationThe evolutions in power systems and electric vehicles, related to the economic opportunities and the environmental issues, bring the need of high power galvanically isolated DC-DC converter. The medium frequency transformer (MFT) is one of its key components, enabled by the increasing switching frequency of modern power semiconductors like silicon carbide transistors or diodes. The increased operating frequency offers small...
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Audio codec employing frequency-derived tonality measure
PublicationA transform codec employing efficient algorithm for detection of spectral tonal components is presented. The tonality measure used in MPEG psychoacoustic model is replaced with the method providing adequate tonality estimates even if the tonal components are deeply frequency modulated. The reliability of hearing threshold estimated using psychoacoustic model with standardized tonality measure and the proposed one is investigated...
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Integrated controller for ultra high frequency technique laboratory
PublicationDepartment of Microwave and Antenna Engineering decided to modernize the laboratory of Ultra High Frequency Techniques. The main change was to replace measurement of the field distribution inside rectangular waveguides by analysing the fields around striplines. This involved the need to overcome several technical and conceptual problems. Precise positioning of the probe and reading the field distribution near the stripline is important...
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Influence of a Radio Frequency on RF Fingerprinting Accuracy Based on Ray Tracing Simulation
PublicationIn this paper the influence of a radio signal frequency on performance of Indoor Positioning System based on fingerprinting has been examined using ray-tracing simulations. It has been simulated how spatial distribution of an RF signal strength change with the signal’s frequency. The results were used to show its’ impact on the behavior of localization algorithms that are employing RSS measurements to determine node’s position...
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Laboratory Load Model Based on 150 kVA Power Frequency Converter and Simulink Real-Time – Concept, mplementation, Experiments
PublicationFirst section of the paper provides technical specification of laboratory load model basing on 150 kVA power frequency converter and Simulink Real-Time platform. Assumptions, as well as control algorithm structure is presented. Theoretical considerations based on criteria which load types may be simulated using discussed laboratory setup, are described. As described model contains transformer with thyristor-controlled tap changer,...
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IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
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Excited state properties of a series of molecular photocatalysts investigated by time dependent density functional theory.
PublicationTime dependent density functional theory calculations are applied on a series of molecular photocatalysts of the type [(tbbpy)2M1(tpphz)M2X2]2+ (M1 = Ru, Os; M2 = Pd, Pt; X = Cl, I) in order to provide information concerning the photochemistry occurring upon excitation of the compounds in the visible region. To this aim, the energies, oscillator strengths and orbital characters of the singlet and triplet excited states are investigated....
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Low-frequency noise in ZrS3 van der Waals semiconductor nanoribbons
PublicationWe report the results of the investigation of low-frequency electronic noise in ZrS3 van der Waals semiconductor nanoribbons. The test structures were of the back-gated field-effect-transistor type with a normally off n-channel and an on-to-off ratio of up to four orders of magnitude. The current–voltage transfer characteristics revealed significant hysteresis owing to the presence of deep levels. The noise in ZrS3 nanoribbons...
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The low-frequency magnetic field emissions on-board of the vessel
Open Research DataThe data represents measurement results performed on board of the vessel. The acquired time-waveforms, corresponding to the instantaneous values of the magnetic field (MF) induction were acquired near the cable supplying the bow thruster motor. Data recording of the magnetic field density (MFD) emissions was carried out with a/d converters of the data...
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The dataset of coupling coefficients for rotating receiver of multicoil dynamic wireless power transfer system
Open Research DataThe provided dataset is part of the simulation results shown in related journal paper "Optimal Rotating Receiver Angles Estimation for Multicoil Dynamic Wireless Power Transfer".
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A novel method of local chirp-rate estimation of LFM chirp signals in the time-frequency domain
PublicationIn the paper, novel dynamic representations of a complex signal in the time-frequency domain are introduced. The proposed approach is based on using the gradient of the short-time Fourier transform complex phase. A channelized instantaneous complex frequency (CICF) and a complex local group delay (CLGD) are included in the presented signal representations. An application of the newly-introduced distributions is demonstrated by...