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Electromodulation of monomer and excimer phosphorescence in vacuum-evaporated films of platinum (II) complexes of 1,3-di(2-pyridyl)benzenes
PublicationElectric field-modulated photoluminescence (EML) measurements are presented for vacuum-evaporated films of cyclometallated Pt (II) complexes of 1,3-di(2-pyridyl) benzenes used as triplet emitters in organic light-emitting diodes (OLEDs). The excimer phosphorescence is quenched by the external electric field of 2.5 MV/cm up to 25% but the same effect on monomer phosphorescence is one order of magnitude smaller. The higher quenching...
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InGaN trapered laser diodes
PublicationW pracy zaprezentowano rezultaty badan nad diodami laserowymi InGaN ze zwężającym się kanałem. Kąty kanałów zmieniane były w zakresie 2 -5 stopni, jak również zmieniana była długość kanału. Wykazano, że w przypadku optymalnych parametrów, parametr M2 (M kwadrat) opisujący odtępstwa wiązki od krzywej Gaussa, wynosił 2.1 przy mocy optycznej 200 mW.
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Discrete Green's function approach to disjoint domain simulations in 3D FDTD method
PublicationA discrete Green’s function (DGF) approach to couple 3D FDTD subdomains is developed. The total-field/scattered-field subdomains are simulated using the explicit FDTD method whilst interaction between them is computed as a convolution of the DGF with equivalent current sources measured over Huygens surfaces. In the developed method, the DGF waveforms are truncated using the Hann’s window. The error varies in the range -65 to -40...
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Sano-Tachiya-Noolandi-Hong, Onsager and Braun models vs Monte Carlo simulation of charge photogeneration in organic solids
PublicationThe Sano-Tachiya-Noolandi-Hong (STNH), Onsager, and Braun models as well as Monte Carlo (MC) simulations of charge recombination/separation have been applied for the first time to reproduce the results of the electromodulated photoluminescence measurements in vacuum-evaporated films of fluorescent materials commonly used in optoelectronic devices. The values of the electron-hole pair final recombination speed in the monomer emitters:...
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Photoconduction and magnetic field effect on photoconduction in hole-transporting star-burst amine (m-MTDATA) films
PublicationPhotoconduction and magnetic field effect on photoconduction have been investigated as a function of electric field strength, excitation light intensity and wavelength in vacuum evaporated films of m-MTDATA (4,4′,4″-tris(N-(3-methylphenyl)-N-phenylylamino) triphenylamine), the starburst amine commonly used as hole-transporting material in organic light-emitting diodes. The photocurrent is found to be generated by the singlet exciton...
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Electromodulation and magnetomodulation of exciton dissociation in electron donor (starburst amine) : electron acceptor (bathocuproine) system
PublicationElectric field dependencies of electromodulated photoluminescence and photocurrents as well as the magnetic field effects on photocurrents, photovoltaic characteristics, electromodulated photoluminescence and photoluminescence have been investigated in vacuum evaporated films of m-MTDATA:BCP (4,4',4''-tris(N-(3-methylphenyl)-N-phenylamino)triphenylamine and bathocuproine) system. The electromodulation processes do remain in accordance...
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Efficiency limit of excitonic photovoltaic cells under phosphor-based white LED illumination
PublicationThe limit of energy conversion of excitonic photovoltaic cells working under white light illumination generated by phosphor-based LED is analysed using the modified Giebink approach. Particularly, the impact of the optical energy gap and energy loss associated with the excitons dissociation at the heterojunction interface on power conversion efficiency of the device are discussed. From the results of our study it follows that the...
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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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Non-isolated resonant quasi-Z-source network DC–DC converter
PublicationA novel non-isolated resonant quasi-impedance (quasi-Z)-source network DC–DC converter is proposed. The resonant impedance source network is derived from the quasi-Z-source network by including the autotransformer-based resonant cell instead of the second inductor of the quasi-Z-network. The leakage inductance of the autotransformer and two resonant capacitors connected in series with the autotransformer windings constitute a high-frequency...
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Dual-band antenna with improved gain for WLAN and ISM applications
PublicationIn this Letter, a dual-band antenna with an improved gain is proposed. The structure features 9.7 and 10.4 dBi gain within 2.4 GHz to 2.5 GHz and 5 GHz to 6 GHz bands, respectively. This makes it suitable for WLAN and ISM applications. The structure comprises an asymmetrical pair of radiators and slots suspended over a reflector. The antenna is optimised in a two-stage process using a trust-region-based gradient search algorithm....
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Detection of anomalies in bee colony using transitioning state and contrastive autoencoders
PublicationHoneybees plays vital role for the environmental sustainability and overall agricultural economy. Assisting bee colonies within their proper functioning brings the attention of researchers around the world. Electronics systems and machine learning algorithms are being developed for classifying specific undesirable bee behaviors in order to alert about upcoming substantial losses. However, classifiers could be impaired when used...
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Imaging polarimeter with high-accuracy measuring principles in crystal optics
PublicationAn imaging polarimeter based on the principles of high-accuracy polarimetry well known in crystal optics is proposed. The application of scientific digital cameras for performance light measurements leads to precise data on polarizers quality, i.e., maps of extinction ratio and transmission axis. Processing of numerous images, acquired at various settings in the polarizer-sample-analyser system, allows to determine the two-dimensional...
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Buzz-based recognition of the honeybee colony circadian rhythm
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Thermochromic liquid crystals applied for heat transfer research
PublicationAutorzy opisali własne wieloletnie doświadczenia z badań wymiany ciepła, w których wykorzystali termochromatyczne ciekłe kryształy. Obejmowały one badania przepływów w kanałach o różnorakiej konfiguracji, badania w przestrzeniach zamkniętych oraz podczas zmiany stanu skupienia badanego płynu.
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Raman investigation of sol-gel-derived hybrid polymers for optoelectronics
PublicationPrzedstawiono wykorzystanie spektroskopii ramanowskiej do kompleksowej diagnostyki polimerów hybrydowych stosowanych w optoelektronice. Zbadano efektywność kolejnych etapów procesu technologicznego: od monomerów do etapu produktu finalnego - cienkich warstw.
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Spectral analysis of mechanical and respiratory influences on width of subarachnoid space assessed with non-invasive method of near-infrared transillumination/back scattering sounding
PublicationW pracy przedstawiono zastosowanie analizy widmowej do badania zmian szerokości przestrzeni podpajęczynówkowej spowodowanych ruchami głowy i wysilonym oddechem w nieinwazyjnej metodzie transiluminacji w bliskiej podczerwieni.
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Liquid crystal display unit for reconfigurable instrument for automotive applications
PublicationRozwój elektronicznych systemów w samochodach (radio, nawigacja, monitorowanie stanu pojazdu, telefon, GPS, itd.) stwarza potrzebę opracowania uniwersalnych i wysoko sprawnych systemów wizualizacji informacji dla kierowcy i pasażerów samochodu. Prezentacja informacji powinna następować z minimalnym zakłóceniem uwagi kierowcy i hierarchiczną klasyfikacją jej priorytetów. Poszukiwanie optymalnych rozwiązań systemów wizualizacji informacji...
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Monitoring of subarachnoid space and cerebrovascular pulsation with near-infrared transillumination/back scattering : new aspects of the method
PublicationW pracy zaprezentowano nowe aspekty nieinwazyjnej metody NIRT-BS w zastosowaniu do zapisu zmian szerokości przestrzeni podpajęczynówkowej (SAS) jako źródła informacji o amplitudzie tętnienia naczyń na powierzchni mózgu.
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Application of polarisation-maintaining side-hole fibres do direct force measurement
PublicationW pracy przedstawiono zastosowanie utrzymujących polaryzację światłowodów typu Side Hole do bezpośredniego pomiaru siły. Dla wybranych struktur tych światłowodów wyznaczono, przy pomocy Metody Elementów Skończonych i metody modów sprzężonych, czułość na siłę działającą prostopadle do osi symetrii światłowodu. Określono zależność tej czułości od poszczególnych wymiarów struktur tych światłowodów. Następnie, biorąc pod...
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Comparative analysis of three‐phase dual active bridge converter with different transformer topology and modern universal control for DC microgrids
PublicationThe presented work discusses issues related to the use of modern multiphase topologies of Dual Active Bridge (DAB)-type converters. Converters of this type are widely used in most DC microgrid applications. The introduction emphasizes a comparative analysis between single-phase and multi-phase DAB topologies within high-power DC microgrids, delving into their respective advantages, drawbacks, design procedures, and considerations...
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Shrinking-shifting and amplifying-shifting device using transformation optics
PublicationBased on transformation optics (TO), this paper uses geometric divisions and linear coordinate transformations to design “shrinking-shifting—and reshaping”, and “amplifying-shifting—and reshaping” devices. The proposed devices can reshape the sizes and locations of the wrapped-objects inside the core-region. The shrinking-shifting device shrinks the larger object into a smaller one and shifts it to different location, whereas the...
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Model analysis of supermode generation in active 5-core optical fibre
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Up-conversion luminescence in germanate glass and double-clad optical fibre co-doped with Yb3+/Eu3+ ions
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Energy conversion in 7-(Diethylamino)coumarin doped PMMA fluorescent fibre
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Capillary waveguide biosensor
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Mathematical analysis of the lasing eigenvalue problem for the optical modes in a layered dielectric cavity with a quantum well and distributed Bragg reflectors
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Organic light emitting devices
PublicationW pracy przedstawiono podstawowe procesy fizyczne zachodzące w organicznych emiterach elektroluminescencyjnych oraz parametry techniczne tego typu układów.
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Identification of inherent noise components of semiconductor devices on an example of optocouplers
PublicationIn the paper, a method of estimation of parameters of Gaussian and non-Gaussian components in the noise signal of semiconductor devices in a frequency domain is proposed. The method is based on composing estimators of two spectra, corresponding to noise (Gaussian component) and two-level RTS noise (non-Gaussian component). The proposed method can be applied for precise evaluation of the corner RTS frequency fRTS in the noise...
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On some ramsey and turan-type numbers for paths and cycles
PublicationUdowodniono, że R(P_3,C_k,C_k)= R(C_k,C_k)= 2k - 1, dla nieparzystych k. Udowodniono, że R(P_4,P_4,C_k) = k + 2 oraz R(P_3,P_5,C_k) = k + 1 dla k > 2.
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Analysis of noise properties of the optocoupler device
PublicationIn the paper the localization of a source of Random Telegraph Signal noise (RTS noise) in optocoupler devices type CNY 17 were defined. The equivalent noise circuit in low frequency noise for these type optocouplers was proposed.
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Optoelectronic and non-linear optical properties of Lu-doped AgGaGe3Se8 crystallites
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Real-time simulator of agricultural biogas plant
PublicationThis article presents a real-time simulator of an agricultural biogas plant. The project contains biogas and biomass circuits simulation, as well as heating circuit simulation with a complete control system and visualization interface of the whole process. The software tool used to simulate the plant work is CFD (Computational Fluid Dynamics), which enables a user to create and test simulation objects based on fundamental physical...
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Dual-wavelength laser polarimeter and its performance capabilities
PublicationA dual-wavelength optical polarimetric approach has been proposed as a means of elimination of the systematic errors and estimation of the optical anisotropy parameters for a single DKDP crystal. Our HAUP-related polarimeter uses two semiconductor lasers with the neighbouring wavelengths of 635 nm and 650 nm. Based on the temperature dependence analysis of small characteristic azimuths of light polarization with respect to the...
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Adaptive estimation of the transformer stray capacitances for DC–DC converter modelling
PublicationNew low cost and accurate estimation method of transformer stray capacitances for wide band DC–DC converter modelling and design is proposed. The Wiener filter (WF) method is applied to estimate the transformer impedance – referred to the selected transformer winding configurations. Laboratory tests are used to adapt the filter, that is to find optimal impedance which minimises mean square error between measured, noise perturbed...
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Stereo vision with Equal Baseline Multiple Camera Set (EBMCS) for obtaining depth maps of plants
PublicationThis paper presents a method of improving the estimation of distances between an autonomous harvesting robot and plants with ripe fruits by using the vision system based on five cameras. The system is called Equal Baseline Multiple Camera Set (EBMCS). EBMCS has some features of a camera matrix and a camera array. EBMCS is regarded as a set of stereo cameras for estimating distances by obtaining disparity maps and depth maps. This...
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Electromagnetic interference frequencies prediction model of flyback converter for snubber design
PublicationSnubber design for flyback converters usually requires experimental prototype measurements or simulation based on accurate and complex models. In this study simplified circuit modelling of a flyback converter has been described to dimension snubbers in early stage of design process. Simulation based prediction of the transistor and diode ringing frequencies has been validated by measurements in a prototype setup. In that way obtained...
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Effect of buffer layers on performance of organic photovoltaic devices based on copper phthalocyanine-perylene dye heterojunction
PublicationPraca przedstawia wyniki badań układu fotowoltaicznego złożonego z cienkich warstw organicznych tworzących złącze (CuPc i MePTCDI), elektrod (ITO i Ag) oraz z warstw buforowych (MoO3 przy ITO i BCP przy Ag).
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Small signal admittance spectroscopy applied for extraction of charge carrier mobility in thin organic layers
PublicationPraca przedstawia nowy sposób wyznaczania ruchliwości nośników ładunku w cienkich warstwach organicznych w oparciu o pomiary widm małosygnałowej admitancji.
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Simulation model for evaluation of packet sequence changed order of stream in DiffServ network
PublicationCurrent packet networks use a large variety of mechanisms which should support QoS (Quality of Service). One of those mechanisms is routing (calculating connection paths for incoming service requests). The most effective mechanism in QoS context is dynamic routing, which is based on the current network state described by the offered traffic matrix and link states. After switching between calculated available paths, connection...
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Buzz-based honeybee colony fingerprint
PublicationNon-intrusive remote monitoring has its applications in a variety of areas. For industrial surveillance case, devices are capable of detecting anomalies that may threaten machine operation. Similarly, agricultural monitoring devices are used to supervise livestock or provide higher yields. Modern IoT devices are often coupled with Machine Learning models, which provide valuable insights into device operation. However, the data...
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Quasi-discrete modelling of PMSM phase currents in drives with low switching-to-fundamental frequency ratio
PublicationThis study proposes a new quasi-discrete approach to modelling the permanent magnet synchronous motor (PMSM). The quasi-discrete modelling reflects the impact of continuous rotor movement, which takes place during a control cycle, on the shape of motor current waveforms. This provides much improvement in current modelling accuracy under inverter low switching-to-fundamental frequency operation. The proposed approach may be used...
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Analysis of luminance distribution uniformity in CAVE-type virtual reality systems
PublicationIn recent years, many scientific and industrial centers in the world developed a virtual reality systems or laboratories. The effect of user “immersion” into virtual reality in such systems is largely dependent of optical properties of the system. In this paper, problems of luminance distribution uniformity in CAVE-type virtual reality systems are analyzed. For better characterization of CAVE luminance nonuniformity corner and...
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Buzz-based recognition of the honeybee colony circadian rhythm
PublicationHoneybees are one of the highly valued pollinators. Their work as individuals is appreciated for crops pollination and honey production. It is believed that work of an entire bee colony is intense and almost continuous. The goal of the work presented in this paper is identification of bees circadian rhythm with a use of sound-based analysis. In our research as a source of information on bee colony we use their buzz that have been...
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Open-Phase Fault Detection Method for Sensorless Five-Phase Induction Motor Drives with an Inverter Output Filter
PublicationThe paper presents the sensorless five-phase induction motor drive implementation with an inverter output filter with third harmonic injection. For the sensorless operation, the required observers are presented for the first and third harmonics with consideration of the inverter output filter. Moreover, the interaction of the observers and the control system is capable to handle a deactivation of one or two phases, which improves...
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Derivation of motor mean phase currents in PMSM drives operating with low switching-to-fundamental frequency ratio
PublicationPulse width modulation (PWM) of inverter output voltage causes the waveforms of motor phase cur-rents to consist of distinctive ripples. In order to provide suitable feedback for the motor current con-trollers, the mean value must be extracted from the currents’ waveforms in every PWM cycle. A com-mon solution to derive the mean phase currents is to sample their value at the midpoint of a symmetrical PWM cycle. Using an assumption...
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Accurate electrothermal modelling of high frequency DC-DC converters with discrete IGBTs in PLECS software
PublicationIn the paper, a novel, improved method of the IGBT junction temperature computations in the PLECS simulation software is presented. The developed method aims at accuracy of the junction temperature computations in PLECS by utilising a more sophisticated model of transistor losses, and by taking into account variability of transistor thermal resistance as a function of its temperature. A detailed description of the proposed method,...
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A simplified behavioral MOSFET model based on parameters extraction for circuit simulations.
PublicationThe paper presents results on behavior modeling of general purpose Metal-Oxide Semiconductor Field-Effect Transistor (MOSFET) for simulation of power electronics systems requiring accuracy both in steady-state and in switching conditions. Methods of parameters extraction including nonlinearity of parasitic capacitances and steady-state characteristics are based on manufacturer data sheet and externally measurable characteristics....
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Rotor-Flux Vector based Observer of Interior Permanent Synchronous Machine
PublicationThe sensorless control system of the interior permanent magnet machine is considered in this paper. The control system is based on classical linear controllers. In the machine, there occurs non-sinusoidal distribution of rotor flux together with the slot harmonics, which are treated as the control system disturbances. In this case, the classical observer structure in the (d-q) is unstable for the low range of rotor speed resulting...
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Battery Technologies in Electric Vehicles: Improvements in Electric Battery Packs
PublicationRestrictions on fossil fuels and related environmental pollution issues motivate many organizations and countries to set their focus on electric vehicles (EVs) rather than conventional internal combustion engine vehicles [1], [2]. EVs require an energy storage system to store converted electric power in another form of energy and then reconvert the stored energy to electric power whenever it is required. The energy stored can be...
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Neural-Network-Based Parameter Estimations of Induction Motors
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