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Effect of TiO2 Concentration on Microstructure and Properties of Composite Cu–Sn–TiO2 Coatings Obtained by Electrodeposition
PublicationIn this work, Cu–Sn–TiO2 composite coatings were electrochemically obtained from a sulfate bath containing 0–10 g/L of TiO2 nanoparticles. The effect of TiO2 particles on kinetics of cathodic electrodeposition has been studied by linear sweep voltammetry and chronopotentiometry. As compared to the Cu–Sn alloy, the Cu–Sn–TiO2 composite coatings show rougher surfaces with TiO2 agglomerates embedded in the metal matrix. The highest...
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Identification of quasi-periodically varying systems with quasi-linear frequency changes
PublicationThe problem of identification of linear quasi-periodically varying systems is considered. This problem can be solved using generalized adaptive notch filtering (GANF) algorithms. It is shown that accuracy of system parameter estimation can be increased if the results obtained from GANF are further processed using a cascade of appropriately designed filters. The resulting generalized adaptive notch smoothing (GANS) algorithms can...
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Evaluation of organic coatings condition with AFM-based method
PublicationThe paper presents an atomic force microscopy (AFM)-based approach to evaluation of local protective properties of organic coatings. Apart from topography, it provides local ac and dc characteristics of examined coating. The method consists in application of ac voltage perturbation signal between conductive AFM tip and coated metal substrate. The resulting current is used to determine local impedance characteristics. Both impedance...
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Analog modelling in qualitative analysis of vibration propagation
PublicationThe theory of dynamic systems is usually used to model the real systems. The models are based on solving ordinary differential equations, partial or difference, which enable obtaining the relation between input signal and the system response (output signal). The analogy between those models and generalized dynamic systems or control systems can be practically used. Vibration propagation can be described in a similar way as the...
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Influence of vacuum sublimation deposited metal layer thickness on metrological parameters of the amperometric gas sensor with Nafion membrane
PublicationThe paper presents the results of investigation on an influence of vacuum sublimation deposited platinum layer thickness on the signal, sensitivity and response time of a prototype of sulphur dioxide sensor with Nafion membrane. The working electrode was made by vacuum sublimation deposition of platinum on a surface of Nafion membrane. Pt layers deposited changed an initial structure of Nafion membrane and that phenomenon was utilized...
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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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Second-order Stark effect and polarizability of a relativistic two-dimensional hydrogenlike atom in the ground state
PublicationThe second-order Stark effect for a planar Dirac one-electron atom in the ground state is analyzed within the framework of the Rayleigh-Schrödinger perturbation theory, with the use of the Sturmian series expansion of the generalized Dirac-Coulomb Green's function. A closed-form analytical expression for the static dipole polarizability of that system is found. The formula involves the generalized hypergeometric function ${}_{3}F_{2}$...
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Harmonic Vibrations of Nanosized Magnetoelectric Bodies with Coupled Surface and Interphase Effects: Mathematical Models and Finite Element Approaches
PublicationThe harmonic problems for piezomagnetoelectric nanosized bodies with taking into account the coupled damping and surface effects are considered on the base of the generalized Gurtin-Murdoch model. In the development of previous investigations, the coupled mechanical, electric and magnetic surface effects with surface inertial terms are introduced into the model. For a homogeneous model, the composite material is considered as homogeneous...
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Rozprzestrzenianie się w podtorzu skutków katastrof kolejowych z udziałem materiałów niebezpiecznych
PublicationDuża część przewozów materiałów niebezpiecznych prowadzona jest koleją. W związku z tym bezpieczeństwo tych przewozów nabiera coraz większego znaczenia. Każda katastrofa z udziałem materiałów niebezpiecznych ma negatywny wpływ na uczestników tego zdarzenia oraz na otaczające środowisko, bowiem jej zasięg na ogół nie jest lokalny. Z tego wynika, że w przypadku zaistnienia katastrofy należy minimalizować jej skutki oraz w dalszych...
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Variable-structure algorithm for identification of quasi-periodically varying systems
PublicationThe paper presents a variable-structure version of a generalized notchfiltering (GANF) algorithm. Generalized notch filters are used for identification of quasi-periodically varying dynamic systems and can be considered an extension, to the system case, of classical adaptive notch filters. The proposed algorithm is a cascade of two GANF filters: a multiple-frequency "precise" filter bank, used for precise system tracking, and a...
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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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Three-objective antenna optimization by means of kriging surrogates and domain segmentation
PublicationIn this paper, an optimization framework for multi-objective design of antenna structures is discussed which exploits data-driven surrogates, a multi-objective evolutionary algorithm, response correction techniques for design refinement, as well as generalized domain segmentation. The last mechanism is introduced to constrain the design space region subjected to sampling, which permits reduction of the number of training data samples...
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Experimentally feasible semi-device-independent certification of four-outcome positive-operator-valued measurements
PublicationRecently the quantum information science community devoted a lot of attention to the theoretical and practical aspects of generalized measurements, the formalism of all possible quantum operations leading to acquisition of classical information. On the other hand, due to imperfections present in quantum devices, and limited thrust to them, a trend of formulating quantum information tasks in a semi-device-independent manner emerged....
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Nonlinear electrical properties of glass-ceramics nanocomposites containing ferroelectric nanocrystallites of Bi2VO5.5
PublicationNonlinear A.C. impedance measurements were conducted in the 50BiV-50SrBAlO nanocomposite as a function of frequency, temperature and A.C. voltage. This material is ferroelectric below temperature of 730 K, and above 730 K is a good ion-conductor. For this nanocomposite a low A.C. voltage of 1 V rms is enough to observe high nonlinearities. The origin of these nonlinear effects depends on the temperature and frequency. In the high...
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Nowa metoda optymalizacji pracy ogniw paliwowych.
PublicationPrzedstawiono dynamiczną technikę impedancją jako doskonałe narzędzie służące do określenia optymalnych warunków pracy ogniw paliwowych. Możliwości tej techniki zostały przedstawione na przykładzie ustalenia optymalnej temperatury pracy. Otrzymane wyniki zostały skonfrontowane z charakterystykami prądowo napięciowymi ogniwa.
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Optimal configuration of an electrode array for measuring ventricles' contraction
PublicationAn influence of an electrode-array configuration on an impedance signal composition for a fixed spatial distribution of its sources is examined in the paper. The Finite Element Method and Geselowitz relationship were used for examining three different electrode-arrays. A sensitivity approach was used to evaluate each configuration assuming that localization of the signal source is known. A conductivity change, thus the source of...
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A comprehensive evaluation of mimosa extract as a corrosion inhibitor on AA6060 alloy in acid rain solution: part I. Electrochemical AC methods
PublicationThe inhibition effect of mimosa extract on the corrosion of AA6060 aluminum alloy in acid rain solution was investigated by electrochemical impedance spectroscopy and dynamic electrochemical impedance spectroscopy (DEIS). All the studied electrochemical parameters showed good corrosion inhibitive characteristics with respect to the aluminum alloy in the tested solution. Inhibitor efficiency increased with the concentration and...
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Variational principles for bound states of Schrödinger and Dirac equations allowing the use of discontinuous trial functions
PublicationWe present systematic constructions of variational principles for energies of bound states of the Schroedinger and Dirac equations. The principles allow the use of discontinuous trial functions. The method employed is based on a generalized Lagrange procedure. Relationships between our variational principles and those available in the literature are established.
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Safety at railway level crossings and Vision Zero
PublicationIn this work, safety analysis at the railway level crossings is presented using advanced mathematical modelling. Resistivity of track subgrade panels is taken into account. The analysis does not refer to the assessment of the current regulations. Specific cases of generalized dynamic system are considered by introducing operations S=Δ, S=P defined in space C(N) of real sequences. In this model, generalized discrete exponential...
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Experimental verification and comparison of mode shape-based damage detection methods
PublicationThis paper presents experimental verification and comparison of damage detection methods based on changes in mode shapes such as: mode shape curvature (MSC), modal assurance criterion (MAC), strain energy (SE), modified Laplacian operator (MLO), generalized fractal dimension (GFD) and Wavelet Transform (WT).
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An Innovative Antenna Array with High Inter Element Isolation for Sub-6 GHz 5G MIMO Communication Systems
PublicationA novel technique is shown to improve the isolation between radiators in antenna arrays. The proposed technique suppresses the surface-wave propagation and reduces substrate loss thereby enhancing the overall performance of the array. This is achieved without affecting the antenna’s footprint. The proposed approach is demonstrated on a four-element array for 5G MIMO applications. Each radiating element in the array is constituted...
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The role of organic and mineral constituents on kerogen transformation ratio
PublicationThe main aim of this dissertation is to determine the role of mineral and organic matter constituents in kerogen transformation ratio. Practical aspects of the work include application of the results in the assessment of hydrocarbon production potential; to make process of hydrocarbon recovery more predictable consistent and efficient. The work used shale from the Vaca Muerta formation from the Nequen basin in Argentina. The formation...
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Fundamentals of classical and analytical mechanics
PublicationThe book is a monographic description of the present attempt to Newtonian and Lagrangian mechanics. But also, it could be found as a supplementary educational material useful for the graduate courses in mechanics taken by students majoring in mechanical engineering, physics or physical science. In the book you can find a brief introduction to concepts and principles of algebra of vectors; Kinematics of particles, mainly focused...
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Low temperature broad band dielectric spectroscopy of multiferroic Bi6Fe2Ti3O18 ceramics
PublicationIn the present research the tool of broadband dielectric spectroscopy was utilized to characterize dielectric behavior of Bi6Fe2Ti3O18 (BFTO) Aurivillius-type multiferroic ceramics. Dielectric response of BFTO ceramics was studied in the frequency domain (Δν=0.1Hz – 10MHz) within the temperature range ΔT=-100°C – 200°C. The Kramers-Kronig data validation test was employed to validate the impedance data measurements and it was found...
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A Stabilized Complex LOBPCG Eigensolver for the Analysis of Moderately Lossy EM Structures
PublicationThis letter proposes a stabilized locally optimal block preconditioned conjugate gradient method for computing selected eigenvalues for complex symmetric generalized non-Hermitian eigenproblems. Effectiveness of the presented approach is demonstrated for a moderately lossy dual-mode dielectric resonator, modeled using finite-element method with higher order elements
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INFLUENCE OF BISMUTH CONTENT ON COMPLEX IMMITTANCE CHARACTERISTICS OF PRESSURELESS SINTERED BiNbO4 CERAMICS
PublicationGoal of the present research was to study immittance properties of BiNbO4 ceramics fabricated by the solid state reaction route followed by pressureless sintering. Four sets of samples were examined, namely the one fabricated from the stoichiometric mixture of oxides, viz. Bi2O3 and Nb2O5 as well as the ones with an excess of 3%, 5% and 10% by mole of Bi2O3. The immittance properties were studied by impedance spectroscopy. Measurements...
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Dynamic Nanoimpedance Characterization of the Atomic Force Microscope Tip-Surface Contact
PublicationNanoimpedance measurements, using the dynamic impedance spectroscopy technique, were carried out during loading and unloading force of a probe on three kinds of materials of different resistivity. These materials were: gold, boron-doped diamond, and AISI 304 stainless steel. Changes of impedance spectra versus applied force were registered and differences in the tip-to-sample contact character on each material were revealed. To...
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PROBLEMS WITH CORROSION PROTECTION STEEL STACKS IN FGD SYSTEMS
PublicationThis paper presents problems associated with corrosion of steel stacks and changes in philosophy of corrosion protection when implemented into flue gas desulphurization systems. In-situ tests were taken by means of electrochemical impedance spectroscopy at a stack which discharges flue gas before wet lime/limestone desulphurization. A very rapid soaking of spherical infill vinylester coating with electrolyte has been observed....
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Investigation of corrosion behavior of 6060 and 6082 aluminum alloys under simulated acid rain conditions
PublicationInstantaneous impedance changes of 6060 and 6082 type aluminum alloys in pure water, and simulated acid rain poured into the pure water was investigated by dynamic electrochemical impedance spectroscopy (DEIS). In this way, the influence of aluminum content on the corrosion behavior of 6060 and 6082 type aluminum alloys immersed in simulated acid rain was determined. The corrosion rate of the alloy decreased with increasing Al...
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Export diversification and economic development: a dynamic spatial data analysis
PublicationThis paper contributes to the empirical literature on the relationship between ‘export variety’ (export diversification) and economic development by relaxing the assumption of cross-country independence and allowing for spatial diffusion of shocks in observed and unobserved factors. Export variety is measured for a balanced panel of 114 countries (1992-2012) using very detailed information on their exports (HS 6-digit product...
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A Systematic Search for New Coupling Schemes of Cross-Coupled Resonator Bandpass Filters
PublicationIn this paper, a systematic approach to an extensive search for topologies of cross-coupled filters with generalized Chebyshev response is presented. The technique applies graph theory to find unique, nonisomorphic filter configurations, and tests whether a specific frequency response can be realized in a given set of topologies. The results of the search are then stored in a database of possible filter configurations.
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Cavitation Erosion of Nodular Cast Iron - Microstructural Effects
PublicationThe paper deals with susceptibility of nodular cast iron with ferritic-pearlitic matrix on cavitation erosion. Cavitation tests were carried out with the use of a cavitation erosion vibratory apparatus employing a vibration exciter operated at frequency of 20 kHz. The study allowed to determine the sequence of subsequent stages in which microstructure of cast iron in superficial regions is subject to degradation. The first features...
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Accelerated design optimization of miniaturized microwave passives by design reusing and Kriging interpolation surrogates
PublicationElectromagnetic (EM) analysis has become ubiquitous in the design of microwave components and systems. One of the reasons is the increasing topological complexity of the circuits. Their reliable evaluation—at least at the design closure stage—can no longer be carried out using analytical or equivalent network representations. This is especially pertinent to miniaturized structures, where considerable EM cross-coupling effects occurring...
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Existence of unbounded solutions to parabolic equations with functional dependence
PublicationThe Cauchy problem for nonlinear parabolic differential-functional equations is considered. Under natural generalized Lipschitz-type conditions with weights, the existence and uniqueness of unbounded solutions is obtained in three main cases: (i) the functional dependence u(·); (ii) the functional dependence u(·) and ∂xu(·); (iii) the functional dependence u(·)and the pointwise dependence ∂xu(t,x).
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Preparation, morphology and properties of natural rubber composites filled with untreated short jute fibres
PublicationGreen composites were obtained by incorporation of short jute fibres in natural rubber matrix using a laboratory two-roll mill. The influence of untreated fibre content (1, 2.5, 5, 7.5 and 10 phr) on the mechanical properties, dynamic mechanical properties, swelling properties was examined. The behaviour of prepared green composites under cyclic compression was also investigated. Fibre dispersion in rubber matrix was studied by...
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Badania eksperymentalne rezonansowego przetwornika piezoelektrycznego typu "unimorph"
PublicationW artykule opisano badania eksperymentalne piezoelektrycznego rezonansowego przetwornika zastosowanego do pomiaru właściwości mechanicznych tkanek miękkich. Po krótkim wstępie w kolejnych punktach przedstawiono opis stanowiska pomiarowego oraz metody pomiaru odkształceń prototypów, przesunięć częstotliwości rezonansowej, impedancji elektromechanicznej i parametrów schematów zastępczych. W dalszej...
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CoRBAC – kontekstowo zorientowany model bezpieczeństwa
PublicationZaproponowano uogólniony model kontroli dostępu do usługowych systemów internetowych uwzględniający różne kategorie kontekstu. Określono wpływ kontekstu na model jak i architekturę systemu bezpieczeństwa. Podano przykład implementacji modelu i architektury bezpieczeństwa dla zestawu usług dotyczących e-uczelni i wstępnie oszacowano zalety takiego rozwiązania.
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Periodic solutions of Lagrangian systems under small perturbations
PublicationIn this paper we prove the existence of mountain pass periodic solutions of a certain class of generalized Lagrangian systems under small perturbations. We show that the found periodic solutions converge to a periodic solution of the unperturbed system if the perturbation tends to 0. The proof requires to work in a rather unusual (mixed) Orlicz–Sobolev space setting, which bears several challenges.
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Potential changes in an electric field and electrolytic corrosion.
PublicationSources have been described of corrosively hazardous electric fields and methods of determination of the corrosion hazard to metal structures caused by electrolytic corrosion. Results of potential and impedance investigations in the field of stray currents flowing out of a tram traction and in the presence of a defined electric field of low frequency have been presented. Uncertainties have been indicated relating to the generally...
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Degradation of protective coatings in steel chimneys of flue gas desulfurisation system
PublicationThis paper presents problems associated with corrosion of steel stacks and changes in philosophy of corrosion protection when implemented into flue gas desulphurization systems. In-situ tests were taken by means of electrochemical impedance spectroscopy at the stack which discharges flue gas before wet lime/limestone desulphurization. A very quick electrolyte absorption by the spherical infill vinylester coating was found using...
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Design optimization of novel compact circular polarization antenna
PublicationThe paper describes a structure and a design optimization procedure of a miniaturized circular polarization antenna with elliptical ground plane slots and feed line with stepped-impedance stubs. Constrained optimization of all antenna parameters is executed in order to explicitly reduce the antenna size while maintaining required impedance axial ratio bandwidth of 5 GHz to 7 GHz at the same time. The size of the optimized antenna...
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Green function diagonal for a class of heat equations
PublicationA construction of the heat kernel diagonal is considered as element of generalized zeta function theory, which gradient at the origin defines determinant of a differential operator in a technique for regularizing quadratic path integral. Some classes of explicit expressions of the Green function in the case of finite-gap potential coefficient of the heat equation are constructed. An algorithm and program for Mathematica are presented...
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Homoclinics for singular strong force Lagrangian systems
PublicationWe study the existence of homoclinic solutions for a class of generalized Lagrangian systems in the plane, with a C1-smooth potential with a single well of infinite depth at a point ξ and a unique strict global maximum 0 at the origin.Under a strong force condition around the singular point ξ, via minimization of an action integral, we will prove the existence of at least two geometrically distinct homoclinic solutions.
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Enhanced susceptibility of SARS-CoV-2 spike RBD protein assay targeted by cellular receptors ACE2 and CD147: Multivariate data analysis of multisine impedimetric response
PublicationSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters the cells through the binding of spike protein to the host cell surface-expressing angiotensin-converting enzyme 2 (ACE2) or by endocytosis mediated by extracellular matrix metalloproteinase inducer (CD147). We present extended statistical studies of the multisine dynamic electrochemical impedance spectroscopy (DEIS) revealing interactions between Spike RBD and...
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Locally sculptured modification of the electrochemical response of conductive poly(lactic acid) 3D prints by femtosecond laser processing
PublicationThis manuscript presents an approach to sculpture high electrochemical activity of the 3D printed electrodes with poly(lactic acid) (PLA) matrix and carbon black (CB) filler by femtosecond laser (FSL) ablation. CB-PLA utility for electrochemical applications depends on a surface modification aiming to remove the PLA and uncover the conductive CB. We have discussed how laser pulse energy is critical for such an activation process....
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Titania nanotubes modified by a pyrolyzed metal-organic framework with zero valent iron centers as a photoanode with enhanced photoelectrochemical, photocatalytical activity and high capacitance
PublicationThe paper discusses the synthesis, photoelectrochemical and electrochemical behaviour of titania nanotube arrays modified by a pyrolyzed metal-organic framework (MOF). A poly(3,4–ethylenedioxyphene) (PEDOT) matrix with an embedded inorganic network of iron hexacyanoferrate (BP) covering TiO2 nanotubes (TNT) is used as a MOF for the further sintering procedure, resulting in a novel, thin film of carbonaceous wrap supported Fe catalytic...
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Termowizja jako narzędzie weryfikacji stanu elementów ochronnych SMD podczas badań udarowych
PublicationPrzedstawiono wyniki badań przyrostów temperatury rejestrowanych za pomocą kamery termowizyjnej ochronnych elementów SMD podczas wykonywania badań odporności na udary napięciowe wykonywane wg normy EN61000-4-5 dla różnych poziomów sprzężeń impedancyjnych
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Analog CMOS processor for early vision processing with highly reduced power consumption
PublicationA new approach to an analog ultra-low power visionchip design is presented. The prototype chip performs low-levelconvolutional image processing algorithms in real time. Thecircuit is implemented in 0.35 μm CMOS technology, contains64 x 64 SIMD matrix with embedded analogue processors APE(Analogue Processing Element). The photo-sensitive-matrix is of2.2 μm x 2.2 μm size, giving the density of 877 processors permm2. The matrix dissipates...
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Three solvers for MIMO noise radar clutter cancellation - a performance comparison
PublicationThe problem of canceling strong clutter echos in a MIMO noise radar is considered. Execution times of three algorithms is compared. The first solution is a standard Least Squares approach employing Cholesky decomposition of the transmitted signal sample autocorrelation matrix. The second approach is based on careful waveform design which guarantees that the signal sample autocorrelation matrix has Toeplitz structure. This enables...
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The inhibition effect of mad Honey on corrosion of 2007-type aluminium alloy in 3.5% NaCl solution
PublicationThe inhibition effect of mad honey on corrosion of 2007-type aluminium alloy in 3.5% NaCl solution was investigated by Tafel extrapolarisation (TP), electrochemical impedance spectroscopy (EIS) and dynamic electrochemical impedance spectroscopy (DEIS). All the studied parameters exhibited good anti-corrosive properties against corrosion of 2007-type aluminium alloy in the test solution; the corrosion rates decreased with the increase...