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Search results for: dc-dc converter modeling
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Fault Loop Impedance Measurement in Circuits Fed by UPS and Principle of Safety Protection
PublicationThis paper indicates a significant problem of uncertainty of fault loop impedance (FLI) measurement in circuits powered from uninterruptible power supply (UPS) (double-conversion AC-DC-AC). The correctly determined value of this impedance, related to the short-circuit current disconnection time and to the reference value, is one of the most important elements that determines the approval of an electrical installation and its receivers...
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Design of Intelligent Low-Voltage Load Switch for Remote Control System in Smart Grid
PublicationCurrent low-voltage load switches do not support remote disconnect/connect and real-time monitoring of a disconnect/connect state. Addressing to these issues, this paper presents a low-voltage load switch for a smart remote control system, which uses a one-chip microcontroller board and a DC step motor drive mechanism and provides the feedback on the switch status also. Arrears disconnect and full-pay connect control is implemented...
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Analysis of exhaled breath for dengue disease detection by low-cost electronic nose system
PublicationThis paper presents a procedure and a set-up of an electronic nose system analyzing exhaled breath to detect the patients suffering from dengue – a mosquito-borne tropical disease. Low-power resistive gas sensors (MiCS-6814, TGS8100) were used to detect volatile organic compounds (VOCs) in the exhaled breath. The end-tidal phase of patients exhaled breath was collected with a BioVOCTM breath sampler. Two strategies were assessed...
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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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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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BADANIA EWALUACYJNE TRANZYSTORA 650 V E-HEMT GAN DO ZASTOSOWAŃW WYSOKOSPRAWNYCH PRZEKSZTAŁTNIKACH DC/DC
PublicationTematem artykułu są badania wysokonapięciowegotranzystora z azotku galu typu E-HEMT w aplikacji przekształtnikaobniżającego napięcie typu buck. W pracy przedstawiono krótkącharakterystykę i zalety półprzewodników szerokoprzerwowych,a także opis tranzystora GS66508P-E03 w obudowie do montażupowierzchniowego (SMD). Następnie poruszono problemchłodzenia łącznika mocy SMD i przeprowadzono badanieporównawcze dwóch układów chłodzenia....
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Flicker Noise in Resistive Gas Sensors—Measurement Setups and Applications for Enhanced Gas Sensing
PublicationWe discuss the implementation challenges of gas sensing systems based on low-frequency noise measurements on chemoresistive sensors. Resistance fluctuations in various gas sensing materials, in a frequency range typically up to a few kHz, can enhance gas sensing by considering its intensity and the slope of power spectral density. The issues of low-frequency noise measurements in resistive gas sensors, specifically in two-dimensional...
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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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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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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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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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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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Structural, magnetic and spectral properties of tetrahedral cobalt(II) silanethiolates: a variety of structures and manifestation of field-induced slow magnetic relaxation
PublicationBlue crystals of five heteroleptic cobalt(II) silanethiolates 1–5 have been obtained by the reaction of [Co{SSi (tBuO)3}2(NH3)]2 with aminopyridines and aminomethylpyridines at an appropriate molar ratio and their structural, spectral, thermal and magnetic properties have been established and described. All complexes 1–5 contain Co(II) ions in a tetrahedral CoN2S2 environment formed by (tBuO)3SiS− residues and pyridines and present...
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Calculation Program Supporting Switched Capacitor DC-DC Charge Pump Design (CP Design Calculator) - PartI: Preface
PublicationPrzedmiot badań i motywy podjęcia pracy. Metoda badawcza. Nota historyczna nt. konwertera Fibonacciego (Fibonacci multiplier) i pompy ładunkowej Makowskiego ("Makowski charge pump"). Przewidywane cele pracy. Podziękowania
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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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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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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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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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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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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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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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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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Calculation Program Supporting Switched Capacitor DC-DC Charge Pump Design (CP Design Calculator) - PartII: User's Guide
PublicationPrzewodnik użytkownika programu wspomagającego projektowanie pomp ładunkowych z przełączanymi pojemnościami. Praca jest podzielona na 3 rozdziały (INTRODUCTI ON, GRAPHICAL USER INTERFACE (GUI), PROGRAM NOTIFICATIONS) i podziękowania.
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Recycled rubber wastes-based polymer composites with flame retardancy and electrical conductivity: Rational design, modeling and optimization
PublicationPolymer recycling techniques experience a maturity period of design and application. Rubbers comprise a high proportion of polymer wastes, highly flammable and impossible to re-melt. Polymer composites based on ground tire rubber (GTR) and ethylene-vinyl acetate copolymer (EVA) containing carbon black (CB) (1–50 phr), with variable EVA/GTR weight composition (10/90, 25/75, 50/50, 75/25 and 90/10), and processing temperature (Low:...
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Calculation Program Supporting Switched Capacitor DC-DC Charge Pump Design (CP Design Calculator) - Part III: Illustrative Examples
PublicationW pracy przedstawiono szereg przykładów użycia programu do obliczeń wspomagających projektowanie pompy ładunkowej, w tym syntezę układu kanonicznego i wyznaczanie wszystkich teoretycznie realizowalnych współczynników przetwarzania (wzmocnień napięciowych), rezystancję wyjściową zastępczą w różnych trybach pracy, sprawność energetyczną, wrażliwość na pojemności pasożytnicze, warunki początkowe w okresowym stanie ustalonym - do współpracy...
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Assessment of organic coating degradation via local impedance imaging
PublicationThe paper presents a new approach to organic coating condition evaluation at micrometer scale using localized impedance measurements. It is based on atomic force microscopy (AFM) in contact mode. Impedance is measured between conductive AFM tip and metal substrate covered with organic coating. A single-frequency voltage perturbation signal is applied between the electrodes and current response signal is registered. As the tip is...
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Edge-Guided Mode Performance and Applications in Nonreciprocal Millimeter-Wave Gyroelectric Components
PublicationThe analogies between the behavior of gyromagnetic and gyroelectric nonreciprocal structures, the use of the simple transfer matrix approach, and the edge-guided (EG) wave property, supported in a parallel plate model for integrated magnetized semiconductor waveguide, are investigated in those frequency regions, where the effective permittivity is negative or positive. As with their ferrite counterparts, the leakage of the EG waves...
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Enhancing electrical properties through in-situ controlled nanocrystallization of V2O5–TeO2 glass
PublicationV2O5–TeO2 glass–ceramics (VTGC) were prepared by controlled annealing of the V2O5–TeO2 glass (VTG), which illustrates a parent glass matrix with a single charge carrier. The annealing proceeded at six temperatures selected between the glass transition and the maximum of the frst crystallization process to obtain various nanocrystallite sizes. Heat treatment caused an increase in DC conductivity by 2.5–3.5 (250–285 °C) order of...
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Development and test of fex, a fingers extending exoskeleton for rehabilitation and regaining mobility
PublicationThis paper presents the design process of an exoskeleton for executing human fingers' extension movement for the rehabilitation procedures and as an active orthosis purposes, together with its first clinical usability tests of a robotic exoskeleton. Furthermore, the Fingers Extending eXoskeleton (FEX) is a serial, under-actuated mechanism capable of executing fingers' extension. FEX is based on the state-of-art FingerSpine serial...
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Structural and electrical transport properties of Pr-doped SrTi0.93Co0.07O3-δ a novel SOEC fuel electrode materials
PublicationSolid Oxide Electrolyzer Cells (SOECs) are very promising electrochemical devices for the production of syngas (H2/CO) by H2O and CO2 co-electrolysis. The structure, microstructure and electrical properties of the fuel electrode material play a crucial role in the performance of the whole cell and efficiency of electrocatalytic reduction of steam into hydrogen. In the present work, a novel Co and Pr co-doped SrTiO3-δ material attracted...
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Studies in the History of Art: National Gallery of Arts, Washington DC
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Sinusoidal Control of a Brushless DC Motor with Misalignment of Hall Sensors
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Viscous versus electromagnetic damping – amplification in a neighbourhood of a mechanism singular position
PublicationIn the paper, damping of vibrations are considered and compared in a mechanical and in a electromechanical system. In the system, a continuous beam is considered as the main vibrating element. The compared dissipations methods are based on: viscous dampers and DC generators. To increase the possible damping effectiveness, velocity amplification is proposed, i.e., a mechanism is introduced between the beam and the damping element....
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Correlations of structural, thermal and electrical properties of sodium doped complex borophosphosilicate glass
PublicationBorophosphosilicate glasses with varying sodium ion concentrations were investigated for their, structural, thermal, and electrical properties. All the obtained glasses were transparent except the glass with the highest sodium content, which exhibited translucency due to inhomogeneities. Increasing sodium content led to reduced boron and silicon content while maintaining a constant B/Si ratio, indicating progressive depolymerization...
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Reconstruction of 3D image of corona discharge streamer
PublicationIn this paper, the method of reconstruction of the 3D structure of streamers in DC positive corona discharge in nozzle-to-plate electrode configuration is presented. For reconstructing of 3D image of corona discharge streamer we propose a stereographical method, where streamers are observed from several directions simultaneously. The multi-directional observation enabled to obtain fine positional coordinates of streamers for a...
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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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Investigations on the immunosuppressive activity of derivatives of mycophenolic acid in immature dendritic cell
PublicationThe main activity of mycophenolic acid (MPA) and its analogs is the inhibition of proliferation of T cells. Here, we hypothesized that MPA and its conjugates inhibits also the activity of antigen-presenting cells (APC) including dendritic cells (DCs). We tested the effect of novel amino acid derivatives of MPA and conjugates of MPA with acridines/acridones on DCs by flow cytometry, ELISA and MLR assay. Both acridines/acridone derivatives...
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Electrical properties and structure of lead-borate glass containing iron ions.
PublicationThe ac and dc conductivity in iron–lead-borate glass samples was investigated in the frequency range from 1 mHz to 1 MHz and in the temperature range from 153 K to 423 K. The structure was investigated by the means of atomic force microscopy (AFM) and the crystalline phases (if present) were identified by the means of X-ray diffractometry. Two types of ac electrical behaviour were observed. The first group of glass samples which...
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Low Frequency Conducted Emissions of Grid Connected Static Converters
PublicationPulse-width modulated rectifiers are nowadays commonly used for AC to DC power conversion. PWM rectification technology is very effective and allows for bidirectional power flow with the possibility of power factor improvement and low-order harmonic emission limitation. Unfortunately, employed PWM boost topology results with generation of input current harmonic distortions in a frequency range tightly correlated to modulation frequency....
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Sensorless Control of Induction Motor Based on Super-Twisting Sliding Mode Observer With Speed Convergence Improvement
PublicationThe super twisting sliding-mode observer (ST-SMO) has been proposed to achieve an effective method for alleviating low-order harmonics of measured quantities, issues related to DC drift, and suppression of chattering due to low-frequency sampling. The conventional ST-SMO, on the other hand, suffers from control delay in the convergence trajectory due to the system disturbance, resulting in decreased anti-disturbance capability...
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High Frequency Harmonics Emission in Smart Grids
PublicationPulse-width modulated rectifiers are nowadays commonly used for AC to DC power conversion. PWM rectification technology is very effective and allows for bidirectional power flow with the possibility of power factor improvement and low-order harmonic emission limitation. Unfortunately, employed PWM boost topology results with generation of input current harmonic distortions in a frequency range tightly correlated to modulation frequency....
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Assessment of Electronic Sensing Techniques for the Rapid Identification of Alveolar Echinococcosis through Exhaled Breath Analysis
PublicationHere we present a proof-of-concept study showing the potential of a chemical gas sensors system to identify the patients with alveolar echinococcosis disease through exhaled breath analysis. The sensors system employed comprised an array of three commercial gas sensors and a custom gas sensor based on WO3 nanowires doped with gold nanoparticles, optimized for the measurement of common breath volatile organic compounds. The measurement...
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Characterization methods of nickel nano-particles obtained by the ex-solution process on the surface of Pr, Ni-doped SrTiO3 perovskite ceramics
PublicationIn this paper, a novel electrode material based on Pr, Ni co-doped strontium titanate ( Sr0.7Pr0.3)xTi1−yNiyO3 with constant amount of 30% praseodymium dopant, different amount of nickel (y = 0.06 and y = 0.10) and additional nonstoichiometry in Sr-site (x = 1; x = 0.9 and x = 0.8) was investigated as fuel electrode for SOEC devices. A porous ceramics were prepared by solid-state reaction method. X-ray diffraction measurements...
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Ellipsometric study of carbon nitride films deposited by DC-magnetron sputtering
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Quasi-resonant dc-link inverter with a reduced number of active elements
PublicationW artykule przedstawiono nową topologię równoległego quasi-rezonansowego obwodu pośredniczącego falownika napięcia. Opisano sekwencje miękkiej komutacji falownika w dwukierunkowym trybie pracy falowniczej i prostowniczej. Analiza układu została zweryfikowana badaniami symulacyjnymi i eksperymentalnymi. Przedstawiona topologia odznacza się prostą strukturą oraz małą ilością elementów aktywnych. Dzięki zastosowaniu krzepkiej strategii...
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AC and DC global electric circuit and the height profile of atmospheric conductivity
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Ellipsometric study of carbon nitride films deposited by DC-magnetron sputtering
PublicationWe report the optical properties of a carbon nitride (CNx) film as a function of nitrogen concentration (N/C) of the deposited film. As nitrogen concentration is increased (N/C ratio) in a CNx film, the refractive index and band gap also increase. The real and imaginary parts, n and k (refractive index and extinction coefficient) of the complex refraction index of carbon nitride films were determined by spectroscopic ellipsometry...
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Trans-Z-source-like inverter with built-in DC current blocking capacitors
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Compatible DC and small-signal MOSFET models for radio and microwave frequency simulation
PublicationZaprezentowano nowy model stałoprądowy tranzystora MOS i kompatybilny z nim uogólniony nie-quasi-statyczny model małosygnałowy. Model stałoprądowy został eksperymentalnie zweryfikowany dla tranzystorów MOS o długości kanału od 75 nm do kilkunastu mikrometrów, a model małosygnałowy od zera herców do 30 GHz.