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Search results for: DC-DC POWER CONVERTERS
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Analytical fluctuation enhanced sensing by resistive gas sensors
PublicationResistance fluctuations across polarised resistive gas sensors were studied in detail to evaluate sensor working conditions for detecting methane and ammonia at various concentrations. The 1/f noise component typically dominates other noise sources up to a few kHz and can be utilised to improve gas selectivity when compared with measurements of the sensor DC resistance. The Arrhenius plot was created and the activation energy for...
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Status report on high temperature fuel cells in Poland – Recent advances and achievements
PublicationThe paper presents recent advances in Poland in the field of high temperature fuel cells. The achievements in the materials development, manufacturing of advanced cells, new fabrication techniques, modified electrodes and electrolytes and applications are presented. The work of the Polish teams active in the field of solid oxide fuel cells (SOFC) and molten carbonate fuel cell (MCFC) is presented and discussed. The review is oriented...
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Analytical comparison between capacitor assisted and diode assisted cascaded quasi-z-source inverters
PublicationQuasi-Z falownik z prostym obwodem impedancyjnym jest bardzo interesującym rozwiązaniem topologicznym ze względu na unikalną możliwość jednostopniowego przekształcanie DC/AC w połączeniu z funkcjami obniżania i podwyższania napięcia. W niektórych aplikacjach jego właściwości podwyższające są jednak niewystarczające. Wyższe napięcie wejściowe można uzyskać w wyniku zastosowania w quasi-Z-falownikach kaskadowych obwodów impedancyjnych....
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Characterization of CaTi0.9Fe0.1O3/La0.98Mg0.02NbO4 composite
PublicationA composite of CaTi0.9Fe0.1O3 and electrolyte material, i.e. magnesium doped La0.98Mg0.02NbO4 was prepared and studied. The phase content and the sample microstructure was examined by an X-ray diffraction method and scanning electron microscopy. EDS measurements were done both for composite samples and the diffusion couple. The electrical properties were studied by four terminal DC method. The Ahigh-temperature interaction between...
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Multilevel inverter neutral-point voltage sensor diagnostic based on the Extended Kalman Filter
PublicationA new algorithm for neutral point voltage imbalance estimation in DC link of the three-level (3L) neutral point clamped (NPC) voltage source inverter (VSI) is proposed. Application of the proposed algorithm does not require any additional sensors. The unbalanced voltage calculation is based on the information derived from the inverter output measured currents and from the knowledge of the load model parameters. In order to estimate...
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Evaluating the mobile robot positions using accelerometer data
PublicationThis paper analyzes the problem of determining the position of a robot using an accelerometer, which is an essential part of inertial measurement units (IMU). The information gained from such a gauge, however, requires double integration of sensor data. To assure an expected effect, a mathematical model of a low-cost accelerometer of the MEMS type is derived. Moreover, in order to improve the performance of positioning based on...
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Evaluating the position of a mobile robot using accelerometer data
PublicationThis paper analyses the problem of determining the position of a robot using an accelerometer, which is an essential part of inertial measurement units (IMU). The information gained from such a gauge, however, requires double integration of sensor data. To assure an expected effect, a mathematical model of a low-cost accelerometer of the MEMS type is derived. Moreover, in order to improve the performance of positioning based on...
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Determination of pitting corrosion stage of stainless steel by galvanodynamic impedance spectroscopy
PublicationThis paper investigates the methodology for differentiation of multistep process of pitting corrosion of AISI 304 stainless steel in the environment of iron (III) chloride. Measurements were performed using Galvanodynamic Electrochemical Impedance Spectroscopy (GDEIS). Application of this methodology allowed monitoring of natural corrosion process without external current (IDC = 0A) nor potential perturbation of the system. Applied...
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Synthesis, structure and physical properties of new intermetallic spin glass-like compounds RE2PdGe3 (RE = Tb and Dy)
PublicationNew intermetallic compounds Tb2Pd1.25Ge2.75 and Dy2Pd1.25Ge2.75 have been synthesized using the arc-melting method. The crystallographic structure and magnetic, electronic transport, and thermal properties are reported. The crystal structure obtained from powder x-ray diffraction analysis suggests that these compounds crystallize in the AlB2-type structure (space group P6/mmm, no. 191) with lattice parameters a = 4.228 53(5)/4.230 54...
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Digital harmonic analysis of cadmium ion reduction on a dropping mercury electrode
PublicationBadano redukcję jonów kadmu na rtęciowej elektrodzie kroplowej. Jako pobudzenie zastosowano sinusoidalny sygnał napięciowy nałożony na liniowo zmieniający się potencjał dc. Przeprowadzono analizę czasowo-częstotliwościową prądu polarograficznego dla reakcji redukcji jonu kadmu na rtęciowej elektrodzie kroplowej. Klasyczna transformacja Fouriera prowadzi do dekompozycji prądu polarograficznego na składowe harmoniczne. Harmoniczne...
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Practical Approach to IP Scheduled Throughput Measurements in Dual Connectivity Systems
PublicationIP scheduled throughput defined according to 3GPP TS 36.314 reflects user throughput regardless of traffic characteristics, and therefore has become one of the most important indicators for monitoring Quality of Service (QoS) of the end user in Evolved Universal Terrestrial Radio Access Network (E-UTRAN). However, networks built on a distributed architecture make the above definition impossible to be applied directly due to the...
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System of protection against electric shock for circuits with power electronics converters
PublicationModern low voltage circuits are very often equipped with power electronics converters, therefore in these circuits non-sinusoidal earth currents (touch currents) may occur. For non-sinusoidal currents safety criteria should be modified. This paper presents these modified criteria and a computer system of protection against electric shock which can be implemented in circuits with power electronics converters. The system is based...
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Performance of zinc-rich coatings evaluated using AFM-based electrical properties imaging
PublicationThe paper presents the results of investigation of polyvinyl zinc-rich coating exposed to 97% relativehumidity atmosphere for 40 days. Condition of the coating and evolution of its protective properties weredetermined with the novel AFM-based approach capable of providing surface profiles, local dc currentmaps as well as local impedance spectra. The proposed technique allowed insight into the local changesof coating topography...
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IMPACT OF DIRECT CURRENT ON NITRIFYING BIOMASS
PublicationEffects of short term exposure of nitrifying biomass to direct current were studied. DC was applied to mixed liquor from municipal BNR plant using graphite electrodes in no substrate limiting conditions. Both, ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) populations were affected by the current, however in opposite ways. The AOB population activity was inhibited by applied voltage. Activity decrease was...
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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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Zagrożenie porażeniem podczas gaszenia pożaru w budynkach z fotowoltaicznymi źródłami energii
PublicationPodczas prowadzenia akcji gaśniczej w budynku z fotowoltaicznymi źródłami energii występuje zwiększone ryzyko porażenia prądem elektrycznym ze względu to, że moduły fotowoltaiczne są źródłami autonomicznymi i mogą generować niebezpieczne napięcie mimo odłączenia inwertera zarówno od strony AC, jak i DC instalacji elektrycznej. Szczególnie duże ryzyko porażenia powstaje podczas dotknięcia przez strażaka przewodów pod napięciem przyłączonych...
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Charge-based deep level transient spectroscopy of B-doped and undoped polycrystalline diamond films
PublicationThe undoped and B-doped polycrystalline diamond thin film was synthesized by hot filament chemical vapor deposition and microwave plasma, respectively. The structural characterization was performed by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The electrical properties of synthesized diamond layer were characterized by dc-conductivity method and charge deep level transient spectroscopy. The B-doped...
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Artificial-Hand Technology—Current State of Knowledge in Designing and Forecasting Changes
PublicationThe subject of human-hand versatility has been intensively investigated for many years. Emerging robotic constructions change continuously in order to mimic natural mechanisms as accurately as possible. Such an attitude is motivated by the demand for humanoid robots with sophisticated end effectors and highly biomimic prostheses. This paper provides wide analysis of more than 80 devices that have been created over the last 40 years....
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Application of Barycentric Coordinates in Space Vector PWM Computations
PublicationThis paper proposes the use of barycentric coordinates in the development and implementationof space-vector pulse-width modulation (SVPWM) methods, especially for inverters with deformed space-vector diagrams. The proposed approach is capable of explicit calculation of vector duty cycles, independentof whether they assume ideal positions or are displaced due to the DC-link voltage imbalance. The use ofbarycentric coordinates also...
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New approaches for improving selectivity and sensitivity of resistive gas sensors: A review
PublicationResistive gas sensors are very popular and reliable but suffer from low selectivity and sensitivity. Various methods have been suggested to improve both features without increasing the number of sensors in gas detection systems. Fluctuation enhanced gas sensing was proposed to improve gas detection efficiency by analyzing low-frequency resistance fluctuations, and noise parameters can be more informative than the single DC resistance...
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Minimization of a ship's magnetic signature under external field conditions using a multi-dipole model
PublicationThe paper addresses the innovative issue of minimizing the ship's magnetic signature under any external field conditions, i.e., for arbitrary values of ambient field modulus and magnetic inclination. Varying values of the external field, depending on the current geographical location, affect only the induced part of ship's magnetization. A practical problem in minimizing the ship signature is separating permanent magnetization...
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Switching Regulation in the Control of 5-Phase Permanent Magnet Synchronous Motor Fed by 3×5 Direct Matrix Converter
PublicationMatrix converter is an AC-AC direct power converter comprising of an array of bi- directional switches. It does not require an intermediate DC-link and allows sinusoidal output waveforms with varying amplitudes and frequencies. The configuration of these bi- directional switches decides the number of inputs and outputs...
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Comparative analysis of switched reluctance motor control algorithms
PublicationПредмет исследования. Развитие микропроцессорной техники и силовой электроники позволило создавать недорогие и эффективные системы управления различными электромеханическими объектами, которые ранее широко не использовались из-за сложности управления. К таким устройствам можно отнести вентильно-индукторные электрические машины. Данные машины широко применяются в различных практических разработках, например, в тяговом электроприводе,...
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Collection Efficiency in Narrow Electrostatic Precipitators with a Longitudinal or Transverse Wire Electrode
PublicationRecently narrow electrostatic precipitators (ESPs) have become a subject of interest because of their possible application in diesel engine exhaust systems. In this work, results of particle collection efficiency measurements in narrow electrostatic precipitators for negative and positive dc voltage polarity are presented. The ESP usedin this work was a parallelepiped equipped with wire discharge electrode and two collecting plate-electrodes....
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Accurate modeling of quasi-resonant inverter fed IM drive
PublicationIn this paper wide-band modeling methodology of a parallel quasi-resonant dc link inverter (PQRDCLI) fed induction machine (IM) is presented. The modeling objective is early-design stage prediction of conductive electromagnetic interference (EMI) emissions of the considered converter fed IM drive system. Operation principles of the selected topology of PQRDCLI feeding IM drive are given. Modeling of the converter drive system is...
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Local properties of organic coatings close to glass transition temperature
PublicationAcrylic coating applied on copper substrate has been investigated at different temperatures starting from the ambient one up to the level above the glass transition temperature. Its local topographic and electric properties have been examined with the atomic force microscopy (AFM) based approach including dc current mapping and local impedance spectroscopy. The local findings have been compared with the information from global...
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Single-phase, Five-level Inverter with SPWM-Based Neutral Point Voltage Balancing Scheme
PublicationMultilevel inverter topologies provide several advantages over two-level inverter configuration. These benefits are the reason for the growing interest in multilevel topologies among research society. One of the most popular topological concepts (diode and active switch clamping) requires neutral-point potential balancing due to series-connected capacitor banks across the input dc link in such derived inverter configurations. This...
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Rubber wastes recycling for developing advanced polymer composites: A warm handshake with sustainability
PublicationRecycling and management of rubber wastes experiences an early-stage maturity in the quest for sustainable and circular materials. Up to now, solutions proposed for sustainable development of rubber wastes are limited, so that properties and performance features of recycled products are inadequate for practical applications. Herein, an experimental protocol is introduced for manufacturing semi-sustainable polymer composites based...
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Numerical Comparison of Damping Amplification Effects Obtained in Neighborhood of a Mechanism Singular Position - Viscous and Electromagnetic Cases
PublicationIn the paper, results of numerical investigations are presented. A continuous beam is considered as the main vibrating element. Two energy dissipations methods are compared: viscous dampers and DC generators. To increase the damping effectiveness, velocity amplification is proposed, i.e., a mechanism is introduced between the beam and the damping element, and the mechanism configuration is set as closed to the singular position...
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Metamaterial-Based Sub-Microwave Electromagnetic Field Energy Harvesting System
PublicationThis paper presents the comprehensive analysis of the sub-microwave, radio frequency band resonant metastructures’ electromagnetic properties with a particular emphasis on the possibility of their application in energy harvesting systems. Selected structures based on representative topologies of metamaterials have been implemented in the simulation environment. The models have been analyzed and their substitute average electromagnetic...
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Electrochemical investigations on corosivity of de-icing liquids for railway infrastructure
PublicationThe paper presents the results of electrochemical tests of the de-icing fluid for railway infrastructure. DC and AC electrochemical tests were performed to determine the corrosion rates of structural steel, cast iron and aluminium in the newly produced fluid. The results were compared with the corrosion rates of the same materials in the fluid without corrosion inhibitors. The obtained test results indicate a low corrosion risk...
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Resistive gas sensors – Perspectives on selectivity and sensitivity improvement
PublicationResistive gas sensors are very popular and relatively inexpensive; they can operate at elevated or room temperature for years on end. The main disadvantage of resistive gas sensors is their limited selectivity and sensitivity, but various methods have been applied to improve their behavior. The composition of the porous gas sensing layer, or changes in the sensor’s operating temperature, can enhance the gas detection ability. Furthermore, emerging...
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Energy storage device based on flywheel, power converters and Simulink real-time
PublicationThis electronic document is a “live” template and already defines the components of your paper [title, text, heads, etc.] in its style sheet. Paper presents information on Energy Storage Device based on Flywheel and bi-directional IGBT Power Converters – designed for LINTE^2 laboratory owned by Gdansk University of Technology in Poland. Paper is divided into four sections. First section of the paper provides introductory information...
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STANY NIEUSTALONE TOWARZYSZĄCE POMIAROWI IMPEDANCJI PĘTLI ZWARCIA W OBWODACH WYJŚCIOWYCH ZASILACZY BEZPRZERWOWYCH UPS
PublicationW pracy przedstawiono metodykę i wyniki pomiarów stanów nieustalonych w zasilaczu bezprzerwowym (UPS) typu on - line. Do rejestracji zdarzeń po stronie zasilania i na wyjściu UPS wykorzystano dwa przyrządy do pomiaru jakości energii elektrycznej zsynchronizowane czasowo. Rejestratory kompresują uzyskane dane pomiarowe, co może wprowadzać dodatkowe błędy pomiaru wielkości mierzonych – napięć i prądów. Dodatkowe rejestracje oscyloskopem...
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AFM-assisted investigation of conformal coatings in electronics
PublicationPurpose – This paper aims to presents a new method of investigation of local properties of conformal coatings utilized in microelectronics. Design/methodology/approach – It is based on atomic force microscopy (AFM) technique supplemented with the ability of local electrical measurements, which apart from topography acquisition allows recording of local impedance spectra, impedance imaging and dc current mapping. Potentialities...
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Multiple output CMOS current amplifier
PublicationIn this paper the multiple output current amplifier basic cell is proposed. The triple output current mirror and current follower circuit are described in detail. The cell consists of a split nMOS differential pair and accompanying biasing current sources. It is suitable for low voltage operation and exhibits highly linear DC response. Through cell devices scaling, not only unity, but also any current gains are achievable. As...
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Hebb–Wagner polarization method for determining the oxygen ion conductivity in barium cerate-zirconate
PublicationIn this work, the partial conductivity of oxygen ions in BaCe0.6Zr0.2Y0.2O3 was studied at different temperatures and water partial pressures. For this purpose, a modified DC Hebb–Wagner polarization method with an electrode blocking for protons and electrons was used. A new type of measuring cell as well as a suitable calculation model were proposed for the determination of partial oxygen ionic conductivity in materials with three...
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Properties of LiMnBO3 glasses and nanostructured glass-ceramics
PublicationPolycrystalline LiMnBO3 is a promising cathode material for Li-ion batteries. In this work, we investigated the thermal, structural and electrical properties of glassy and nanocrystallized materials having the same chemical composition. The original glass was obtained via a standard melt-quenching method. SEM and 7Li solid-state NMR indicate that it contains a mixture of two distinct glassy phases. The results suggest that the...
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Sensing the onset of epoxy coating degradation with combined Raman spectroscopy/atomic force microscopy/electrochemical impedance spectroscopy
PublicationThe paper presents the results of investigation on epoxy resin durability upon 12-week exposure to UV radiation. The aim was early determination of the onset of epoxy degradation and for this purpose an epoxy film on steel substrate systems were periodically inspected using Raman spectroscopy, atomic force microscopy and electrochemical impedance spectroscopy. The behaviour of examined polymer could be divided into three periods: immunity,...
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Nanostructure and dielectric behavior of vanadate glasses containing BaTiO3
PublicationThe ac and dc electrical conductivity of barium titanate doped bismuth-vanadate as-quenched and heat-treated materials was measured in the frequency range from 1 mHz to 1 MHz and in the temperature range from 153 K to 423 K with the impedance spectroscopy method. The microstructure was investigated by means of XRD, scanning electron microscopy (SEM), atomic force microscopy (AFM) and confocal microscopy. The obtained results showed...
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Superconductivity in CaBi2
PublicationSuperconductivity is observed with critical temperature Tc = 2.0 K in self-flux-grown single crystals of CaBi2. This material adopts the ZrSi2 structure type with lattice parameters a = 4.696(1) Å, b = 17.081(2) Å and c = 4.611(1) Å. The crystals of CaBi2 were studied by means of magnetic susceptibility, specific heat and electrical resistivity measurements. The heat capacity jump at Tc is DC/gTc = 1.41, confirming bulk superconductivity;...
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Optimizing conductivity in Na-V-Te-O glass through controlled heat treatment
PublicationSemiconducting Na2O-V2O5-TeO2 glasses with various Na2O contents were melted and subjected to controlled heating to improve conductivity. Topography analysis were performed using confocal microscopy and scanning electron microscopy on both as-quenched and heat-treated samples. X-ray diffraction confirmed the amorphous nature of the samples post-melting, with subsequent heating resulting in the formation of nanocrystallites primarily...
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Falowniki napięcia z quasi-rezonansowym obwodem pośredniczącym w układach napędowych
PublicationW monografii przedstawiono zagadnienia związane z wykorzystaniem pośrednich przemienników częstotliwości z rezonansowymi oraz quasi-rezonansowymi obwodami pośredniczącymi w układach napędowych. Omówiono wpływ przełączania „twardego” przy niezerowych prądach i napięciach łączników na właściwości eksploatacyjne elektrycznego układu napędowego. Ponadto dokonano przeglądu wybranych topologii przekształtników DC/AC, zapewniających techniki...
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Electrical properties of Na2O-CaO-P2O5 glasses doped with SiO2 and Si3N4
PublicationSodium-calcium-phosphate glasses doped with SiO2 or Si3N4 having similar sodium ion concentrations were prepared by melt quenching. The conductivity was measured by impedance spectroscopy under nitrogen atmosphere in a wide frequency range (10 mHz–1 MHz) and wide temperature range (153–473 K). At 36.6 °C, DC conductivities of all glasses vary between 1.1 ∗ 10−12 and 8.9 ∗ 10−12 S cm−1 and have similar activation energies (between...
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Portable exhaled breath analyzer employing fluctuation-enhanced gas sensing method in resistive gas sensors
PublicationThis paper presents a portable exhaled breath analyser, developed to detect selected diseases. The set-up employs resistive gas sensors: commercial MEMS sensors and prototype gas sensors made of WO3 gas sensing layers doped with various metal ingredients. The set-up can modulate the gas sensors by applying UV light to induce physical changes of the gas sensing layers. The sensors are placed in a tiny gas chamber of a volume...
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Ionic conductivity behavior by activated hopping conductivity (AHC) of barium aluminoborosilicate glass–ceramic system designed for SOFC sealing
PublicationNon-conducting BaO-B2O3-Al2O3-SiO2 parent glasses designed for solid oxide fuel cell (SOFC) sealing applications were prepared using the melt-quenching technique. The glass formation region was determined according to phase equilibrium relations and was found to be in the composition range 70BaO-(x)Al2O3-(10−x)B2O3-20SiO2 where 3.0 < x < 6.0 wt%. The conductivity values obtained conductivity ranged from 10−5 to 10−10 S/cm at temperatures...
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Advanced operating methods
PublicationSelected operating methods of resistive gas sensors were presented. The methods utilize flicker noise (1/f noise), which gives additional information about ambient gas when compared with the recorded changes of DC resistance only. Methods of flicker noise measurements were outlined. Recently developed prototype gas sensors comprising golden nanoparticle functionalized with organic ligands can generate intense flicker noise induced...
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Low-frequency noise in Au-decorated graphene–Si Schottky barrier diode at selected ambient gases
PublicationWe report results of the current–voltage characteristics and low-frequency noise in Au nanoparticle (AuNP)-decorated graphene–Si Schottky barrier diodes. Measurements were conducted in ambient air with addition of either of two organic vapors, tetrahydrofuran [(CH2)4O; THF] and chloroform (CHCl3), as also during yellow light illumination (592nm), close to the measured particle plasmon polariton frequency of the Au nanoparticle...
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Highly stable CsFAPbIBr perovskite solar cells with dominant bulk recombination at real operating temperatures
PublicationMixed-cation mixed-halide perovskite solar cells have been characterized in DC at different temperatures (from −20 °C up to 50 °C) and the time evolution of the device efficiency has been assessed using different degradation protocols (indoors and outdoors). The completely planar p–i–n structure is ITO/CuNiOx/PTAA/CsFAPbIBr/PCBM/PEI/Ag. Pristine current–voltage characteristics barely show hysteresis, at any temperature. Open circuit...
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An Extended Control of the Input Angle for Matrix Converters Connected with the Non-Unity Power Factor Loads.
PublicationThis paper proposes a novel PWM modulation algorithm for Multiphase Conventional Matrix Converters (MCMC), with 3 inputs and k outputs, using the transfer function of the load angle. The proposed approach extends the range of power angle control at the input during the operation with a maximum voltage transfer ratio. The proposed concept is based on the Direct Analytic Voltage PWM (DAV--PWM) modulation with an elliptical trajectory...