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Search results for: MIECZYSŁAW FELD
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Analysis of the influence of ferromagnetic contaminations in plastics on the measurements of disturbances of magnetic field of the Earth
PublicationPlastics can be contaminated with small particles or filings with ferromagnetic properties. These contaminations cause significant disturbances in the magnetic field in the case of taking measurements of very low magnetic fields. The analysis of the influence of contaminated plastics on magnetic measurements is presented in this paper.
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Social Entrepreneurship Avenues for the Field Development through Research Paradigm Intersection Discussion
PublicationThe aim of this paper is to identify and provide key arguments for employing integrative approach in the choice of research paradigm for studying social entrepreneurship phenomenon. The fact that social entrepreneurship as a field of research is at its preliminary stage, serves as argument and gives freedom in the discussion of the choice of employing a research paradigm. The author does so through identifying commonalities and...
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Experimental and theoretical investigation of pressure field in a shroudclearance. Part II: Theoretical results
PublicationPrzedstawiono wyniki obliczeń teoretycznych metodami CFD rozkładu ciśnienia w uszczelnieniu nadbandażowym stopnia powietrznej turbiny modelowej. Badania przeprowadzono stosując metody: Miltiple Reference Frame, Mixing Plane iSliding Mesch. Wyniki porównano z rezultatami badań eksperymentalnych.
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Determination of equivalent circuit parameters of an induction motor using field calculation software
PublicationSimulation of the drive system comprising a power electronic converter and an induction motor requires that the equivalent circuit parameters of the motor are known. These parameters can be either measured or calculated. A method of calculation of self and mutual inductances that are parameters of a polyphase model of the motor is presented in the paper. All self-inductances and mutual inductances have been calculated using the...
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Dynamics based on six-field theory of shells in the context of energy-conserving scheme
PublicationPraca dotyczy zaproponowanego algorytmu zachowującego energię w całkowaniu równań ruchu powłok sprężystych sformułowanych w ramach teorii sześcioparametrowej. Zawiera podstawowe założenia konieczne do formułowania schematów i podstawowe testy numeryczne. Aproksymacja przestrzenna zagadnienia oparta jest o Metodę Elementów Skończonych zaś aproksymacja w czasie wykorzystuje regułę punktu środkowego. Przykłady analizy dynamicznej...
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The utilization of sludge generated in coagulation of fish processing wastewater for liquid feed production
PublicationWykorzystano koagulację do wydzielenia ze ścieków z przemysłu rybnego białek i tłuszczów. Uzyskany osad pokoagulacyjny dodawano do produkcji rybnych hydrolizatów białkowych. Zmodyfikowano proces wytwarzania rybnych hydrolizatów z wykorzystaniem kwasów siarkowego (VI) oraz ortofosforowego (V).
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Cascaded doubly fed induction generator using PFC rectifiers
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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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Over-Voltage Studies in Inverter Fed Induction Motor Drives
PublicationW pracy przedstawiono metodę identyfikacji pojemności pasożytniczych uzwojeń silników asynchronicznych uwzględniającą ich rozłożony charakter. Przedstawiony szerokopasmowy model obwodowy uzwojeń silnika asynchronicznego pozwala na modelowanie zjawisk przepięciowych w silnikach asynchronicznych, w szczególności zasilanych poprzez przekształtniki energoelektroniczne. Zaproponowana metoda analizy umożliwia również określanie składowych...
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Conception for diagnosing SI engines fed with biofuel in operation conditions
PublicationThe article deals with the question of diagnosing the high power self ignition (SI) engines fed with pro-ecologic fuels in an aspect of appearing operation problems. There has been presented the specific of action and techno-operation profile of the combustion engine foreseen as an investigations object. The preliminary conception of diagnostic investigations of the engine 7L35MC type produced in H. Cegielski - Poznan S.A. factory...
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Antimicrobial properties of pristine and Pt-modified titania P25 in rotating magnetic field conditions
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Low-Field NMR Study of Shortcake Biscuits with Cricket Powder, and Their Nutritional and Physical Characteristics
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Low Field NMR Studies of Wheat Bread Enriched with Potato Juice During Staling
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Phylogenetic and geographic analysis of fowl adenovirus field strains isolated from poultry in Poland
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Dielectric response of electric-field distortions of the twist-bend nematic phase for LC dimers
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Exploring perceptions of pro environmental educational mobile applications based on semantic field analysis
PublicationThe paper aims to identify multidimensional perceptions of mobile apps by their users. Special attention has been paid to pro-environmental educational apps. Semantic field analysis and measurement of emotional temperatures were performed to achieve this goal. Transcripts from seven focus group interviews were used as research material. The results indicate that functionality based on a reward or benefit system reinforces environmentally...
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Large electric field effects on photoluminescence of organic Eu3+ complex-based electroluminescent emitters
PublicationW pracy zaobserwowano silne wygaszenie fotoluminescencji pod wpływem zewnętrznego pola elektrycznego w organicznym kompleksie europu Eu(III). Wygaszenie fotoluminescencji przypisano elektrycznopolowej dysocjacji ekscytonów oraz anihilacji ekscytonów na wstrzykniętym do próbki ładunku elektrycznym.
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Analysis of Reliability Structures for Fire Signaling Systems in the Field of Fire Safety and Hardware Requirements
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Spectral analysis of nonstationary low-frequency magnetic-field emissions from ship's power
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Application of matching pursuit based method to identify sources of time-vary magnetic field
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Numerical Simulation of Temperature Field in Steel under Action of Electron Beam Heating Source
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Numerical Estimate of the Spectral Resonance Structure Frequency Scale of Natural ULF Magnetic Field
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Geomagnetic Storms and Substorms as Space Weather I nfluence on Atmospheric Electric Field Variations
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Simplified method of simulation of temperature field control system of induction heated calender rolls
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Dynamic Formation and Breaking of Disulfide Bonds in Molecular Dynamics Simulations with the UNRES Force Field
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Replica Exchange and Multicanonical Algorithms with the Coarse-Grained United-Residue (UNRES) Force Field
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Acoustic field and the entropy mode induced by it in a waveguide filled with some non-equilibrium gases
PublicationThe non-linear propagation of an acoustic beam in a rectangular waveguide is considered. The medium of sound propagation, is a gas where thermodynamically non-equilibrium processes take place: such as exothermic chemical reactions or excitation of vibrational degrees of a molecule’s freedom. The incident and reflected compounds of the acoustic field do not interact in the leading order in the case of periodic weakly nonlinear sound...
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The adaptive backstepping control of PMSM supplied by current source inverter for the field weakening region
PublicationThe sensorless control system of permanent magnet synchronous motor PMSM supplied by current source inverter for field weakening operation is presented in this paper. The adaptive backstepping control system and the backstepping speed observer are presented. The control system is based on multi-scalar variables. The control variables are: dc-link voltage and the output current vector pulsation. The control system was named voltage...
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Sensorless Field Oriented Control of Five Phase Induction Motor with Third Harmonic Injection
PublicationIn this paper, a sensorless field oriented control system of five-phase induction machine with the 3rd harmonic rotor flux is presented. Two vector models, α1-β1 and α3-β3, were transformed into d1-q1, d3-q3 models oriented in rotating frames, which correspond to the 1st and 3rd harmonic plane respectively. The authors proposed the linearization of the model in d-q coordinate frames by introducing a new variable “x” which is proportional...
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Determination of odour concentration by TD-GC×GC–TOF-MS and field olfactometry techniques
PublicationField olfactometry is one of the sensory techniques used to determine odour concentration, in atmospheric air, directly in emission sources. A two-dimensional gas chromatography with time of flight mass spectrometer (GC×GC–TOF-MS) allows performing the chemical characterization of various groups of chemical compounds, even in complex mixtures. Application of these techniques enabled determination of odour concentration level in...
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Resonance microstrip structure with patch of arbitrary convex geometry with the use of field matching technique
PublicationAn analysis of the resonance frequency problem of planar microstrip structure with patch of arbitrary convex geometry is presented. A full-wave analysis is employed utilizing a combination of Galerkin’s moment method and field matching technique. In this approach, a field matching technique is adopted to calculate the patch surface current densities, and next the method of moments is utilized to calculate resonance frequencies...
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Field tests on hydrodynamic and hybrid operation of a bi-directional thrust bearing of a pump-turbine
PublicationIn vertical shaft pump turbines operating in pumped storage power plants an important role is played by a thrust bearing. Because of bi-directional character of operation, thrust bearing tilting pads have to be supported symmetrically, which is known to be unfavourable from the point of view of their performance. Large thrust bearings have to be carefully designed so as to minimise excessive thermo-elastic pad deformations. The...
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State of the art in the field of emission reduction of sulphur dioxide produced during coal combustion
PublicationThe need for clean coal technologies to reduce the adverse environmental impact of coal combustion products has been grounded. The article deals with information concerning present and future technologies, directed towards the struggle against air pollution by SO2, produced during coal combustion. Their classification and critical rating from economical and technological points of views (including those developed by authors) have...
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Extraction of antenna pattern from near field antenna measurements distorted by undesired emission
PublicationIn this paper authors present experimental correction of antenna pattern obtained from near field measurements when they are distorted by determined electromagnetic emission. Such situation may be met e.g. when feeding or supply subsystem interacts with antenna radiation pattern due to self-emission. Presented results of experiments show effectiveness of extraction of antenna pattern utilizing near field antenna measurements.
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Estimation of the effectiveness of nbpt for limiting ammonia emission from urea based on the field experiments
PublicationThe efectiveness of the ammonia emission reduction from NBPT-stabilized urea was investigating in 2011 during a field experiment on a grassland plot fertilized with a one-time dose of 60 kgN/ha. The obtained reduction coefficient of ammonia emission equaled 73% and 39-51% relative to erea without the inhibitor and ammonium nitrate, respectively.
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Magnetic field gradient as the most useful signal for detection of flaws using MFL technique
PublicationThe magnetic flux leakage (MFL) technique is extensively used for detection of flaws as well as for evaluation of their dimensions in ferromagnetic materials. However, proper analysis of the MFL signal is hindered by the MFL sensor velocity causing distortions of this signal. Traditionally measured components of the MFL signal are particularly sensitive to the scanning velocity. In this paper, an another signal – the gradient of...
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Propagation in the Open Cylindrical Guide of Arbitrary Cross Section With the Use of Field Matching Method
PublicationA simple solution to propagation problem in open waveguides and dielectric fibers of arbitrary convex cross section is presented. The idea of the analysis is based on the direct field matching technique involving the usage of the field projection at the boundary on a fixed set of orthogonal basis functions. A complex root tracing algorithm is utilized to find the propagation coefficients of the investigated guides. Different convex...
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Effect of pine impregnation and feed speed on sound level and cutting power in wood sawing
PublicationThe sound levels along with the cutting power registered during the sawing process of the impregnated and non-impregnated pine wood at two feed speeds are shown and compared in this paper. Statistically significant differences in the acoustic signals occurred at the lower feed rate. The differences became smaller with an increase in the feed speed. In contrast to the sound signal, the differences...
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Effect of GO-Fe3O4 and rotating magnetic field on cellular metabolic activity of mammalian cells
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Detection and localization of selected acoustic events in 3D acoustic field for smart surveillance applications
PublicationA method for automatic determination of position of chosen sound events such as speech signals and impulse sounds in 3-dimensional space is presented. The events are localized in the presence of sound reflections employing acoustic vector sensors. Human voice and impulsive sounds are detected using adaptive detectors based on modified peak-valley difference (PVD) parameter and sound pressure level. Localization based on signals...
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Numerical tests of time-stepping schemes in the context of FEM for 6-field shell dynamics
PublicationThe paper deals with integration of dynamic equations of irregular shells performed with relatively long time steps. Numerical instability appearing often in this kind of analysis motivated the authors to present some studies based on numerical tests referring to convergence problems of finite element analysis as well the applied stability conditions. The analysis is carried out on simulations of shell dynamics with the where the...
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Analysis of magnetic field distribution inside ferromagnetic thin shells during degaussing process
PublicationAnalysis of the demagnetization of a large ferromagnetic object like a ship, was conducted. The approximate mathematical model in the form of a long cylindrical shell of constant magnetic permeability was applied. The discrete degaussing winding was assumed and the current density and magnetic flux density distribution in the ferromagnetic shell wall were determined. Based on the frequential and temporal analysis the recommended...
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Statistical evaluation of the effectiveness of different extraction techniques for determining robenidyne levels in poultry feed.
PublicationPoprzez zastosowanie testu Kruskala-Wallisa i chemometrycznej techniki analizy podobieństwa porównano efektywność sześciu różnych technik ekstrakcji (wytrząsanie, ekstrakcja w aparacie Soxhleta, w aparacie Soxteca, wspomaganej ultradźwiękami, wspomaganej promieniowaniem mikrofalowym oraz przyspieszonej ekstrakcji rozpuszczalnikiem) na podstawie wyników odzysku robenidyny z próbek paszy dla ptaków. W zależności od zastosowanej techniki...
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Electric field and charge induced quenching of luminescence in electroluminescent emitters based on lanthanide complexes
PublicationW pracy badano ładunkowe i elektrycznopolowe wygaszanie ekscytonóww układzie dwuamina TPD: organiczny kompleks europu przez pomiar zaników fotoluminescencji w zewnętrznym polu elektrycznym.
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Propagation in a ferrite circular waveguide magnetized through a rotary four-pole magnetic field
PublicationOpracowano uproszczony model matematyczny użyteczny do badania zjawisk polowych występujących w falowodzie cylindrycznym magnesowanym czterobiegunowym polem obrotowym. Wykazano, że falowód ten może być wykorzystany jako przesuwnik fazy lub układ zmieniający polaryzację.
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Influence of plastic deformation on stray magnetic field distribution of soft magnetic steel sample
PublicationThe effect of various combinations of conditions, i.e., presence of the Earth’s magnetic field during and after deformation on the distribution of stray magnetic field of S355 steel sample, which is locally deformed, was investigated. Some of the stages of the experiment were carried out in zero magnetic field. Compensation of the Earth’s magnetic field was obtained by the application of a pair of Helmholtz coils. These coils are...
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Stress anisotropy characterisation with the help of Barkhausen effect detector with adjustable magnetic field direction
PublicationIn the paper we describe a novel apparatus for the measurement of the Barkhausen noise (BN) angular dependence, which in turn may be indicative of the stress induced anisotropy of magnetic properties. Such dependence can be further used for the stress distribution evaluation. The change of magnetization direction in the material is obtained by varying the magnetic flux density in two perpendicular yokes of the apparatus. We present...
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Air journal bearing utilizing near-field acoustic levitation: stationary shaft case
PublicationResults of a study to examine a unique idea of self-levitating journal bearing are presented in this paper. the idea represents a radical departure from the current bearing technology. it utilisesacoustic levitation, which relies on the sound energy radiated by an object supporting a load. acoustic levitation has been demonstrated to support loads of up to 10 kg. in order to support a load theacoustic wave emitted by the radiating...
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Discussion of Derivability of Local Residual Stress Level from Magnetic Stray Field Measurement
PublicationThe NDT procedure dubbed ‘metal magnetic memory’ method and the related ISO 24497 standard has found wide industrial acceptance in some countries, mainly in Russia and China. The method has been claimed by some researchers (Roskosz and Bieniek in NDT&E Int 45:55–62, 2012; Wilson et al. in Sens Actuators A 135:381–387, 2007) as having potential for quantitative determination of local residual stress state in engineering structures,...
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Magnetic field effects in dye-sensitized solar cells controlled by different cell architecture
PublicationThe charge recombination and exciton dissociation are generally recognized as the basic electronic processes limiting the efficiency of photovoltaic devices. In this work, we propose a detailed mechanism of photocurrent generation in dye-sensitized solar cells (DSSCs) examined by magnetic field effect (MFE) technique. Here we demonstrate that the magnitude of the MFE on photocurrent in DSSCs can be controlled by the radius and...