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Search results for: frequency-dependent%20couplings
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Resonant ultrasonic spectroscopy in high-voltage varistor spectroscopy
PublicationResonant spectroscopy is an effective non-destructive testing method focused on defects in tested objects. The testing procedure, based on the resonant pattern, allows rejection of the tested samples with defects which do not fit the pattern. A sweeping frequency method has been used to measure the spectrum of resonances in high-voltage varistors. As a result we can observe resonances that depend directly on inhomogeneity of the...
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Finite Element Approaches to Model Electromechanical, Periodic Beams
PublicationPeriodic structures have some interesting properties, of which the most evident is the presence of band gaps in their frequency spectra. Nowadays, modern technology allows to design dedicated structures of specific features. From the literature arises that it is possible to construct active periodic structures of desired dynamic properties. It can be considered that this may extend the scope of application of such structures. Therefore,...
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Local impedance spectra of organic coatings
PublicationPublikacja przedstawia nowe podejście do lokalnych spektroskopowych pomiarów impedancyjnych powłok organicznych, oparte o mikroskop sił atomowych pracujący w trybie kontaktowym. Pomiędzy nieporuszającą się igłę mikroskopu i podłoże metalowe pokryte powłoką epoksydową przyłożono serię sinusoidalnych napięciowych sygnałów pobudzenia w zadanym zakresie częstotliwości. W ten sposób zarejestrowano lokalne widma w trybie "frequency by...
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Automated Reduced Model Order Selection
PublicationThis letter proposes to automate generation of reduced-order models used for accelerated -parameter computation by applying a posteriori model error estimators. So far,a posteriori error estimators were used in Reduced Basis Method (RBM) and Proper Orthogonal Decomposition (POD) to select frequency points at which basis vectors are generated. This letter shows how a posteriori error estimators can be applied to automatically select...
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Operational algae bloom detection in the Baltic Sea using GIS and AVHRR data
PublicationDuring the blooming season, algal colonies can, in extreme cases, cover up to 200 000 square kilometres of the Baltic Sea water surface. Because the position and shape of the blooms may significantly change in very short time due to the influence of wind and waves, regular monitoring of the blooms' development is necessary. Currently, the desired monitoring frequency may only be achieved by means of remote sensing. The article...
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Receiver of Doppler multistatic system for moving target detection and tracking
PublicationThe article presents a method for solving major structural problems that occur in the receiver used in the multistatic Doppler system, aimed at determination of the trajectory and velocity of a moving target. In the system two transmitters emit acoustic continuous sinusoidal waves at different frequencies. The signals, scattered from a moving target are received by four hydrophones. Beside of the echoes, much larger signals coming...
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Nonlinear and linear impedance of bismuth vanadate ceramics and its relation to structural properties
PublicationThe nonlinear and linear electrical properties, topography, and microstructure of bismuth-vanadate ceramics, were studied. The structurewas observed with the use of X-ray diffraction (XRD), scanning electronmicroscopy (SEM), atomic force microscopy (AFM) and confocal microscopy methods. The obtained results showed that ceramic is porous. Two phase transitionswere determinedwith the use of DSC measurements. The linear and nonlinear ac...
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Kinetic analysis of the stage for a high speed steam turbine
PublicationThis article analyzes possibilites of resonances within a control stage for a high speed steam turbine. This stage hase been based on assembling of a single blade to a rotating disk and increasing of rigidity of the system by using of a bandage. In the analysis will be nd a possiblity of resonance frequency, and mistuning by showing safety working ranges. The calculations have bean used the3D modal and harmonic analysis by the...
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Digital microcontroller for sonar waveform generator
PublicationGenerating sounding signals is essential for the operation of active sonar. The system should be highly reliable. This can be achieved through architecture, communication between the devices, and a well-designed and self–testing software. The system presented in the article is responsible for the generation of hydroacoustic sounding signals, and ensures proper interaction between power amplifiers and power supplies. Thanks to its...
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Geometry Parametric Model Order Reduction with Randomly Generated Projection Bases
PublicationIn this work, a reduced-order model for geometry parameters and fast frequency sweep is proposed. The Finite Element Method is used to solve time-harmonic Maxwell’s equations. Taking into account the electromagnetic field does not arbitrarily vary as a function of frequency and geometry parameters, a low dimension system manifold is identified. Thus, the original Finite Element problem can be approximated by a model of reduced...
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Rapid surrogate-assisted statistical analysis of compact microstrip couplers
PublicationIn this paper, a technique for low-cost statistical analysis and yield estimation of compact microwave couplers has been presented. The analysis is executed at the level of a fast surrogate model representing selected characteristic points of the coupler response that are critical to determine satisfaction/violation of the prescribed design specifications. Because of less nonlinear dependence of the characteristic points on geometry...
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Text Categorization Improvement via User Interaction
PublicationIn this paper, we propose an approach to improvement of text categorization using interaction with the user. The quality of categorization has been defined in terms of a distribution of objects related to the classes and projected on the self-organizing maps. For the experiments, we use the articles and categories from the subset of Simple Wikipedia. We test three different approaches for text representation. As a baseline we use...
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Identification and non-integer order modelling of synchronous machines operating as generator
PublicationThis paper presents an original mathematical model of a synchronous generator using derivatives of fractional order. In contrast to classical models composed of a large number of R-L ladders, it comprises half-order impedances, which enable the accurate description of the electromagnetic induction phenomena in a wide frequency range, while minimizing the order and number of model parameters. The proposed model takes into account...
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Fully Separated Flow Control Using DBD Plasma Actuators Located at the Leading Edge of an Airfoil
PublicationIn the framework of the PLASMAERO European project, experiments were conducted to investigate the authority of surface DBD plasma actuators to alter a fully separated flow around an airfoil in order to improve its aerodynamic performances in its natural stall regime. In this paper, unsteady excitation control is more specifically investigated. The key control parameter studied here is the burst frequency which periodically imposes...
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Efficient signal processing in spectroscopic optical coherence tomography
PublicationSpectroscopic optical coherence tomography (SOCT) is an extension of a standard OCT technique, which allows to obtain depth-resolved, spectroscopic information on the examined sample. It can be used as a source of additional contrast in OCT images e.g. by encoding certain features of the light spectrum into the hue of the image pixels. However, SOCT require computation of time-frequency distributions of each OCT A-scan, what is...
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Composition Patterns of Contemporary Polish Residential Building Facades
PublicationThis study aims to define the types of composition patterns of contemporary Polish multi-family building facades. The authors define the compositional patterns to determine their frequency. Analyses carried out on the basis of photos and visualizations of 113 examples of architecture from Poland identified groups of common features of facades. Statistical analyses of these features resulted in six types of compositions. Clear differences...
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Efficient FPGA Implementation of an RFIR Filter Using the APC–OMS Technique with WTM for High-Throughput Signal Processing
PublicationNowadays, Finite Impulse Response (FIR) filters are used to change the attributes of a signal in the time or frequency domain. Among FIR filters, a reconfigurable filter has the advantage of changing the coefficient in real-time, while performing the operation. In this paper, the Anti-Symmetric Product Coding (APC) and Odd Multiple Storage (OMS) modules are utilized to implement the reconfigurable FIR filter (RFIR–APC–OMS). Herein,...
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Conducted emi propagation modelling in the wound components.
PublicationThe modelling of EMC behaviour of power electronics converters require specific models of devices which are adequate in a wide frequency range. A novel equivalent-circuit model of the inductor, suitable for EMC applications, has been developed and validated. The model can be used for the analyses of wounded components' behaviour in the conducted-EMI frequency range. The parameters of the proposed model can be evaluated based on...
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Polarization interferometer using a Liquid Crystalline Polymer waveplate for wavelength measurement
PublicationA two-beam polarization interferometer for measuring wavelength changes of a tunable semiconductor laser was designed, built and tested. This interferometer uses a λ/8 waveplate made from Liquid Crystalline Polymer in order to generate two output signals in quadrature. The λ/8 waveplate can be manufactured either on a beamsplitter face or on the mirror surface, reducing the cost and complexity of the optomechnical assembly. Experiment...
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MONITORING OF PERMANENT GPS STATIONS AT THE SUDETY MOUNTAINS
PublicationThe aim of this paper is to show time-dependent baseline variation between GPS stations situated in South-East Poland. This study was based on daily data analysis of selected GPS stations: WROC, GOPE, MOPI, KRAW and KATO. The start date of the analysis is linked at every station with the beginning of its operation and the closing date of the operation is in 2006. The multiresolution signal decomposition method has been used to...
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Characterization of d-xylose reductase, XyrB, from Aspergillus niger
PublicationD-xylose reductase is a member of the aldo-keto reductase family, and is involved in D-xylose and L-arabinose conversion through the Pentose Catabolic Pathway (PCP) in fungi. In this study, we biochemically characterized a newly identified second D-xylose reductase (XyrB) from Aspergillus niger. This NADPH-dependent reductase is able to efficiently convert D-xylose and L-arabinose, and it has the highest affinity for these sugars...
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EMISJA AKUSTYCZNA JAKO SYGNAŁ DIAGNOSTYCZNY ODWZOROWUJĄCY ZMĘCZENIOWE ZUŻYCIE WARSTW ŚLIZGOWYCH PANWI ŁOŻYSK GŁÓWNYCH I KORBOWYCH SILNIKÓW O ZAPŁONIE SAMOCZYNNYM
PublicationW artykule przedstawiono wyniki badań laboratoryjnych, z których wynika, że emisja akustyczna (EA) może być uznana za sygnał diagnostyczny, przydatny do identyfikacji stanu technicznego łożysk głównych i korbowych okrętowych silników o zapłonie samoczynnym. Wykazano w nim bowiem, że parametry emisji akustycznej takie jak: czas rejestracji, energia sygnału, amplituda sygnału, ilość przekroczeń poziomu dyskryminacji, czas narastania,...
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A three-dimensional periodic beam for vibroacoustic isolation purposes
PublicationThis paper presents results of investigations on a three-dimensional (3-D) isotropic periodic beam. The beam can represent a vibroacoustic isolator of optimised dynamic characteristics in the case of its longitudinal, flexural and torsional behaviour. The optimisation process concerned both the widths as well as the positions of particular frequency band gaps that are present in the frequency spectrum of the beam. Since the dynamic...
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Compensation Topologies in IPT Systems: Standards, Requirements, Classification, Analysis, Comparison and Application
PublicationWireless power transfer devices are becoming more relevant and widespread. Therefore, an article is devoted to a review, analysis and comparison of compensation topologies for an inductive power transfer. A new classification of topologies is developed. A lot of attention is paid to the problems of the physical fundamentals of compensation work, standards, safety, and five main topology requirements. It is determined, that topologies...
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High-performance activation of ozone by sonocavitation for BTEX degradation in water
PublicationThis work presents a novel advanced oxidation process (AOP) for degradation of emerging organic pollutants – benzene, toluene, ethylbenzene and xylenes (BTEXs) in water. A comparative study was performed for sonocavitation assisted ozonation under 40–120 kHz and 80–200 kHz dual frequency ultrasounds (DFUS). Based on the obtained results, the combination of 40–120 kHz i.e., low-frequency US (LFDUS) with O3 exhibited excellent oxidation...
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A systematic review on cellular responses of Escherichia coli to nonthermal electromagnetic irradiation
PublicationInvestigation of Escherichia coli under electromagnetic fields is of significance in human studies owing to its short doubling time and human‐like DNA mechanisms. The present review aims to systematically evaluate the literature to conclude causality between 0 and 300 GHz electromagnetic fields and biological effects in E. coli. To that end, the OHAT methodology and risk of bias tool were employed. Exponentially growing cells exposed...
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Generalization of Kramers-Krönig relations for evaluation of causality in power-law media
PublicationClassical Kramers-Krönig (K–K) relations connect real and imaginary parts of the frequency-domain response of a system. The K–K relations also hold between the logarithm of modulus and the argument of the response, e.g. between the attenuation and the phase shift of a solution to a wave-propagation problem. For square-integrable functions of frequency, the satisfaction of classical K–K relations implies causality in the time domain....
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AeroSense Measurements: Wind Tunnel Ecole Centrale Lyon
Open Research DataData from wind tunnel tests of Aerosesne measurement system installed on NACA 63418 aerfoil in the anechoic wind tunnel at the Ecole Centrale Lyon.
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Near-Infrared III Nanophosphorswith Cr3+Ni2+ Energy Transfer for Bioimaging
Open Research DataIn the biomedical field, the use of fluorescence imaging in the second near-infrared (NIR-II) region is growing rapidly because it imparts the advantages of reduced autofluorescence and low photon scattering. The advantage of reduced scattering is that it increases penetration depth in vivo and improves imaging clarity. Herein, this work uses mesoporous...
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Optimization of the femtosecond laser impulse for excitation and the spin-orbit-mediated dissociation in the NaRb molecule
Open Research DataHigh accuracy ab initio potential energy curves (1tSigma+, 2sSigma+, 1tPi), electronic transition dipole moment function (1tSigma+ - 1tPi), and spin-orbit coupling (2sSigma+ - 1tPi) have been calculated for the NaRb molecule. The time-dependent excitation and dissociation processes in the polar alkali diatomic NaRb molecule and the quantum properties...
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Impedance spectra of ZnO varistor type 280 model O M ver. 89
Open Research DataThe impedance spectrum of high-voltage ZnO varistor obtained using FRA EIS impedance spectrosocpy measurement method. The 1V sinusoidal excitation was used. The frequency range was chosen from 10 kHz down to 100 uHz. The object under test and the measuring instrument were placed in a Faraday cage due to high impedance of the object. The data was acquired...
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Ambient vibrations - footbridge over the Kolibkowski Stream in Gdynia, span P2
Open Research DataAmbient vibration tests carried out on the P2 span of the footbridge over the Kolibkowski Stream. The research was carried out using a set of 14 acceleration sensors - MEMS accelerometers TE 4332M3-002 and TE 4312M3-002, which allowed for simultaneous measurement and recording of 20 acceleration channels. These sensors are characterized by a natural...
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Ambient vibrations - footbridge over the Kolibkowski Stream in Gdynia, span P3
Open Research DataAmbient vibration tests carried out on the P3 span of the footbridge over the Kolibkowski Stream. The research was carried out using a set of 14 acceleration sensors - MEMS accelerometers TE 4332M3-002 and TE 4312M3-002, which allowed for simultaneous measurement and recording of 20 acceleration channels. These sensors are characterized by a natural...
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Low-Cost Quasi-Global Optimization of Expensive Electromagnetic Simulation Models by Inverse Surrogates and Response Features
PublicationConceptual design of contemporary high-frequency structures is typically followed by a careful tuning of their parameters, predominantly the geometry ones. The process aims at improving the relevant performance figures, and may be quite expensive. The reason is that conventional design methods, e.g., based on analytical or equivalent network models, often only yield rough initial designs. This is especially the case for miniaturized...
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Rola nowego tramwaju wodnego w Gdańsku
PublicationStreszczenie Tramwaj wodny – środek miejskiej komunikacji zbiorowej czy jednostka przewozów turystyczny? Identyfikacja, zestawienie i analiza czynników transportu nowopowstałej usługi przewozowej z komunikacją miejską i przewozem turystycznym tj. :cennik biletów, sposobu dystrybucji biletów, czasu przejazdu dostępności, przebieg trasy i częstotliwości kursowania. Wskazanie funkcji przewozowej tramwaju wodnego w Gdańsku.
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Wpływ postrzeganego ryzyka oraz czynników wizerunkowych na zamiar zakupu marek własnych sieci handlowych
PublicationCelem przeprowadzonych badań była analiza wpływu wizerunku sklepu, postrzeganego ryzyka oraz wizerunku cenowego marek własnych na zamiar ich zakupu. Dokonano replikacji modelu zaproponowanego przez M.F. Diallo i w jej ramach zastosowano technikę wywiadu realizowanego za pośrednictwem Internetu (CAWI) i przeprowadzono analizy z wykorzystaniem modelu równań strukturalnych (SEM) przy pomocy oprogramowania AMOS. Stwierdzono, że zamiar...
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Właściwości elektryczne szkło-ceramiki zawierającej ferroelektryczną fazę BiV
PublicationKompozyty szklano - ceramiczne zawierające nanokryształy posiadają właściwości fizyczne, które nie są możliwe do uzyskania w innych materiałach. Dzięki możliwości wytworzenia szkło - ceramik posiadających kryształy o różnej wielkości (nano, mikro...) i różnorodnego typu, można w istotny sposób kontrolować właściwości elektryczne takich materiałów. Stała dielektryczna faz ferroelektrycznych jest bardzo wrażliwa na zmiany rozmiarów...
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Sathwik Prathapagiri
PeopleSathwik was born in 2000. In 2022, he completed his Master’s of Science in Biological Sciences and Bachelor’s of Engineering in Chemical Engineering in an integrated dual degree program from Birla Institute Of Technology And Science, Pilani, India. During his final year, he worked as a research intern under Dr Giri P Krishnan at Bazhenov lab, University of California San Diego school of medicine to pursue his Master’s Thesis on...
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Profile irregularities of turned surfaces as a result of machine tool interactions
PublicationThe paper describes the influence of the machining operation on a surface, which disturbs the projection of the tool profile in the form of its relative movements with respect to the object. The elements of the machine tool undergo constant wear during the machining process, it is therefore important to recognize the effects of their influence on the surface's irregularities. Amplitude-frequency analysis of lateral profiles has...
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New bulk liquid membrane oscillator composed of two coupled oscillators with diffusion-mediated physical coupling
PublicationA new type of bulk liquid membrane system, which represents the first example of a bulk liquid membrane oscillator characterised by the presence of two coupled oscillators, is described. When the benzyldimethyltetradecylammonium chloride surfactant undergoes an oscillatory mass transfer through a nitromethane liquid membrane, a new liquid layer (phase X) appears between the membrane and the acceptor phase. Kinetic analysis provides...
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Application of Maximum Lenght Sequence in Silent Sonar
PublicationSilent sonars are designed to reduce the distance over which their sounding pulses can be detected by intercept sonars. In order to meet this objective, we can use periodical sounding signals that have low power, a very long duration and wide spectrum. If used in the silent sonar's receiver, matched filtration ensures very good detection of motionless or slow moving targets. However, it is more difficult to detect echo signals...
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Measurements of flicker noise in supercapacitor cells
PublicationFlicker noise (1/f-like noise) is often used to assess the quality of various materials and devices. This phenomenon has been observed in different electrochemical devices or reactions (e.g., smart windows, pitting corrosion events). In our exploratory studies we consider how to measure and utilize 1/f noise for the quality assessment of supercapacitors. This task requires special attention because of enormous capacitance of the...
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Influence of Sn and Pb Ions Substitutions on Dielectric Properties of Barium Titanate
PublicationThe results of the microstructural and dielectric measurements of (Ba1-xPbx)(Ti1-xSnx)O3 (BPTSx) (x = 0, 0.05, 0.10, 0.30) polycrystalline samples are presented. The samples were obtained by means of a high temperature synthesis and their expected stoichiometry was confirmed by energy dispersive spectroscopy (EDS) measurements. The dielectric properties of BPTSx were studied with the use of broadband dielectric spectroscopy. The...
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Water-mediated long-range interactions between the internal vibrations of remote proteins
PublicationIt is generally acknowledged that the mobility of protein atoms and the mobility of water molecules in the solvation layer are connected. In this article, we answer the question whether a similar interdependence exists between the motions of atoms of proteins separated by the hydration layers of variable thickness. The system consisted of a kinesin catalytic domain and a tubulin dimer. It was studied using molecular dynamics simulations....
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Fluctuation-Enhanced Sensing of Organic Vapors by Ink-Printed MoS2 Devices under UV Irradiation
PublicationThis work presents the results of fluctuationenhanced sensing (FES) of selected organic gases by MoS2 sensor fabricated via a simple ink printing method. We demonstrate that low-frequency noise measured under UV irradiation (275 nm) is more sensitive to different gases than measured in the dark. The noise at 1 Hz under UV light increased 3.3, 3.5, 1.6, and 2.9 times for chloroform, tetrahydrofuran, acetonitrile, and acetone ambiances, respectively....
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The Influence of Thin Gold Electrodes on the High-Temperature Impedance of Oxide Glasses
PublicationThe influence of thin gold electrodes on the electrical measurements of glasses at high temperatures was studied using impedance spectroscopy. The impedance was measured several times over a wide frequency range from 10 mHz to 1 MHz and the temperature ranged from 213 to 673 K under air and nitrogen atmospheres. The results showed a drop in the conductivity of more than an order of magnitude at a temperature around 603 K during...
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RCDs Tripping in the Range from DC to AC 50 kHz for Slowly Rising Residual Current
PublicationThe wide use of power electronic converters means that in many low-voltage systems earth fault currents containing components from DC to AC of various frequencies have to be taken into account. Due to the tendency to increase the modulation frequency in converters, components of higher frequencies may be in the order of several tens of kilohertz. Therefore, it is very important to verify the behavior of devices for protection against...
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Compact 4 × 4 butler matrix with non‐standard phase differences for IoT applications
PublicationButler matrices represent a popular class of feeding networks for antenna arrays. Large dimensions and the lack of flexibility in terms of achievable output phase difference make conventional Butler structures of limited use for modern communication devices. In this work, a compact planar 4 × 4 matrix with non-standard relative phase shifts of –30º, 150º, –120º, and 60º has been proposed. The structure is designed to operate at...
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A New Approach to Capacitive Sensor Measurements Based on a Microcontroller and a Three-Gate Stable RC Oscillator
PublicationA complete smart capacitive sensor solution basedA complete smart capacitive sensor solution based on a microcontroller was developed. This approach includes the development of both the hardware and software. The hardware part comprises an 8-bit microcontroller equipped with two timers/counters and a three-gate stable RC relaxation oscillator. The software part handles system configuration, measurement control, communication control,...
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IFE: NN-aided Instantaneous Pitch Estimation
PublicationPitch estimation is still an open issue in contemporary signal processing research. Nowadays, growing momentum of machine learning techniques application in the data-driven society allows for tackling this problem from a new perspective. This work leverages such an opportunity to propose a refined Instantaneous Frequency and power based pitch Estimator method called IFE. It incorporates deep neural network based pitch estimation...