Filters
total: 403
filtered: 317
-
Catalog
Chosen catalog filters
Search results for: HARMONIKI SFERYCZNE
-
The vortex flow caused by sound in a bubbly liquid
PublicationGeneration of vorticity in the field of intense sound in a bubbly liquid in the free half-space is considered. The reasons for generation of vorticity are nonlinearity, diffraction, and dispersion. Acoustic streaming differs from that in a Newtonian fluid. Under some conditions, the vortex flow changes its direction. Conclusions concern streaming induced by a harmonic or an impulse Gaussian beam.
-
A BRIEF REVIEW AND COMPARISON OF SELECTED EXPERIMENTAL METHODS FOR MEASURING NATURAL FREQUENCIES OF CIRCULAR SAW BLADES
PublicationDifferent methods for the empirical determination of the natural frequencies of circular saw blades are presented. Stationary methods, such as the harmonic and impulse tests, are discussed and the results of related comparison are given. The comparison of the methods revealed their degree of practical usefulness and their accuracy in determining natural frequencies. A combination of specific methods is proposed, which should allow...
-
The Influence of LED Lighting Sources on the Nature of Power Factor
PublicationThis article presents measurements of electric power absorbed by a newly built facility for office and scientific research activities. These measurements highlighted the need for compensation of capacitive reactive power—not predicted by the designer—due to the vast use of LED lighting in the facility. The article also describes a reactive power compensation system, designed on the basis of the above-mentioned measurements, and...
-
Anti-plane shear waves in an elastic strip rigidly attached to an elastic half-space
PublicationWe consider the anti-plane shear waves in a domain consisting of an infinite layer with a thin coating lying on an elastic half-space. The elastic properties of the coating, layer, and half-space are assumed to be different. On the free upper surface we assume the compatibility condition within the Gurtin–Murdoch surface elasticity, whereas at the plane interface we consider perfect contact. For this problem there exist two possible...
-
Fazy stacjonarne na bazie pochodnych kaliks[4]arenów w konformacji 1,3-naprzemianległej chemicznie związanych z żelem krzemionkowym, jako nowy typ wypełnień w chromatografii cieczowej
PublicationW prezentowanym opracowaniu monograficznym przedstawione zostały wyniki badań autorki dotyczące wykorzystania pochodnych kaliks[4]arenów w konformacji 1,3-naprzemianległej do otrzymywania nowego typu wypełnień kolumn chromatograficznych. Pierwsza część pracy jest przeglądem literaturowym dotyczącym syntezy kaliksarenów, ich budowy, różnorodności konformacyjnej, a także możliwości modyfikacji zarówno w obrębie górnej, jak i dolnej...
-
Direct spectrum detection based on Bayesian approach
PublicationThe paper investigates the Bayesian framework's performance for a direct detection of spectrum parameters from the compressive measurements. The reconstruction signal stage is eliminated in by the Bayesian Compressive Sensing algorithm, which causes that the computational complexity and processing time are extremely reduced. The computational efficiency of the presented procedure is significantly...
-
Determination of the shape of the CFGFT cylindrical column based on laboratory tests
PublicationAnalyses were carried out on glass-fibre-reinforced polymer tube columns with reference to laboratory tests. The angles of the glass fibre beams were 20◦, 55◦ and 85◦. The study employed non-classical operational calculus. Various modulated harmonic signal shapes were considered for columns and tubes at buckling. The buckling loads were assessed and compared for different models.
-
Metrological analysis of an computerized system of protection against electric shock in circuits with variable speed drives
PublicationDrive systems, that can be operated at variable speed, are equipped with power electronics converters. This causes distortion of the earth current, and consequently the need to take into account the use of proper protective devices in relation to earth current harmonics. This paper presents a system for protection against electric shock in circuits with power electronics converters and metrological analysis indicating the requirements...
-
Fully Adaptive Savitzky-Golay Type Smoothers
PublicationThe problem of adaptive signal smoothing is consid-ered and solved using the weighted basis function approach. Inthe special case of polynomial basis and uniform weighting theproposed method reduces down to the celebrated Savitzky-Golaysmoother. Data adaptiveness is achieved via parallel estimation.It is shown that for the polynomial and harmonic bases andcosinusoidal weighting sequences, the competing signal estimatescan be computed...
-
Acoustic Streaming Induced by Periodic and Aperiodic Sound in a Bubbly Liquid
PublicationThe vortex ow which follows intense sound propagating in a bubbly liquid, is considered. The reasons for acoustic streaming are both nonlinearity and dispersion. That makes streaming especial as compared with that in a Newtonian uid. Conclusions concern the vortex ow induced in a half-space by initially harmonic or impulse Gaussian beam. The vortex ow recalls a turbulent ow with increasing in time number of small-scale vortices...
-
Zobrazowania w ultrasonografii
PublicationOmówiono zagadnienia powstawania współczesnych zaawansownych form zobrazowańultrasonograficznych w aspekcie technicznych i technologicznych możliwościich opracowania i aplikacji w produkowanym sprzęcie, ze wskazaniem harmoni-cznego rozwoju tych możliwości we wszystkich dziedzinach naukowych, techni-cznych i technologicznych mających zastosoawanie w konstrukcji ultrasonogra-fów.
-
Comparative Analysis of Reactive Power Compensation Devices in a Real Electric Substation
PublicationA constant worldwide growing load stress over a power system compelled the practice of a reactive power injection to ensure an efficient power network. For this purpose, multiple technologies exist in the knowledge market out of which this paper emphasizes the usage of the flexible alternating current transmission system (FACTS) and presents a comparative study of the static var compensator (SVC) with the static synchronous compensator...
-
Propagation of Acoustic Disturbances in Shallow Sea
PublicationPropagation of acoustic waves in shallow sea differs fundamentally from the same phenomenon occurring in deep sea in view of non-negligible distance from the sea bottom in the first case, where presence of two regions limiting the water layer results in the acoustic pressure distribution induced by a harmonic source has an interferential nature as a result of multi-path propagation of the acoustic signal. These interferential properties...
-
Theory versus experiment for vacuum Rabi oscillations in lossy cavities. II. Direct test of uniqueness of vacuum
PublicationThe paper continues the analysis of vacuum Rabi oscillations we started in part I [Phys. Rev. A 79, 033836 (2009)]. Here we concentrate on experimental consequences for cavity QED of two different classes of representations of harmonic-oscillator Lie algebras. The zero-temperature master equation, derived in part I for irreducible representations of the algebra, is reformulated in a reducible representation that models electromagnetic...
-
Determination of chlorine concentration using single temperature modulated semiconductor gas sensor
PublicationA periodic temperature modulation using sinusoidal heater voltage was applied to a commercial SnO2 semiconductor gas sensor. Resulting resistance response of the sensor was analyzed using a feature extraction method based on Fast Fourier Transformation (FFT). The amplitudes of the higher harmonics of the FFT from the dynamic nonlinear responses of measured gas were further utilized as an input for Artificial Neural...
-
A filter bank solution for active power filter control algorithms
PublicationThb paper describes the proposed active power fiIter (APF) with a new control circuit based on an algorithm using ufilter bank and a harmonic predictor. The conirol circuit was realized using the digiiaI signor processor ADSP-21065L and FPGA circuiL In the proposed circuit transient performunee of APF is improved The active power fdter circuil has been built and teste6 and some illustrative, experimental results are uIso presented...
-
Wpływ uwarunkowań rzeczywistych na pracę równoległego filtru aktywnego sterowanego ze sprzężeniem od prądu zasilającego
PublicationW artykule przedstawiono wpływ uwarunkowań rzeczywistych na pracę równoległego filtru aktywnego i zdolność kompensacji prądów harmonicznych. Zbadano wpływ opóźnień czasowych wynikających z implementacji cyfrowej sterowania, wpływ impedancji zwarciowej sieci zasilającej oraz błędów generowania napięcia przekształtnika na jakość kompensacji filtru. Badania symulacyjne przeprowadzono dla trzech układów sterowania: otwartego, zamkniętego...
-
Impact of Energy Slope Averaging Methods on Numerical Solution of 1D Steady Gradually Varied Flow
PublicationIn this paper, energy slope averaging in the one-dimensional steady gradually varied flow model is considered. For this purpose, different methods of averaging the energy slope between cross-sections are used. The most popular are arithmetic, geometric, harmonic and hydraulic means. However, from the formal viewpoint, the application of different averaging formulas results in different numerical integration formulas. This study...
-
Wybrane reakcje kwasu neopentylidenofosforoditiowego oraz jego zastosowanie do otrzymywania niesymetrycznie podstawionego wiązania disulfidowego lub sulfidowego.
PublicationŁatwo dostępne mieszane bezwodniki fosforoditio-tiokarboksylowe są doskonałymi, chemoselektywnymi odczynnikami tioacylującymi azotowe lub siarkowe nukleofile w obecności grupy hydroksylowej. Takie właściwości tych bezwodników umożliwiły otrzymywanie hydroksy tioamidów, hydroksy ditioestrów i kwasów tiohydroksamowych z substratów zawierających niechronioną grupę hydroksylową. Natomiast, N,N-dipodstawione oraz N-podstawione zatłoczone...
-
Coupled DEM/CFD analysis of impact of free water on the static and dynamic response of concrete in tension regime
PublicationW tym artykule zbadano numerycznie quasi-statyczne i dynamiczne zachowanie częściowo nasyconego płynem betonu w warunkach dwuwymiarowego (2D) jednoosiowego rozciągania w mezoskali. Obliczono, jaki wpływ ma zawartość wolnego płynu porowego (gazu i wody) na proces pękania i wytrzymałość betonu w rozciąganiu. Do symulacji zachowania betonu całkowicie i częściowo nasyconego płynem w warunkach quasi-statycznych i dynamicznych wykorzystano...
-
Multilevel Converters
PublicationThe newest Special Section is intended to focus on recent research and trends in application of multilevel converters. Multilevel converters have been extensively developed over the last two decades and show several important advantages of power electronic circuits, such as: operation at high voltages, harmonics reduction, higher efficiency, modularity, smaller size and lower cost. Also, thanks to increasing interest in renewable...
-
Comprehensive compensation of grid current distortion by shunt active power filters
PublicationThe paper presents a comprehensive approach to the compensation of grid current distortion in shunt active power filter systems. Four sources of current distortion are addressed: imperfect grid synchronization caused by the distortion in the grid voltages, time delays in the evaluation of grid voltages and computation of compensating currents, fluctuations of the dc bus voltage, and the distortion of inverter output voltages due...
-
Generalized adaptive comb filter with improved accuracy and robustness properties
PublicationGeneralized adaptive comb lters can be used to identify/track parameters of quasi-periodically varying systems.In a special, signal case they reduce down to adaptive comblters, applied to elimination or extraction of nonstationarymulti-harmonic signals buried in noise. We proposea new algorithm which combines, in an adaptive way, resultsyielded by several, simultaneously working generalizedadaptive comb lters. Due to its highly...
-
Ways of Harmonising Polish Competition Law with the Competition Law of the EU
PublicationThis article discusses the harmonisation of laws within the EU focusing on the specific ways of achieving an approximation of the Polish legal system with European competition law. It identifies and gives an overview of three specific ways of harmonising national laws with EU antitrust provisions: (1) spontaneous (or bottom-up) harmonisation; (2) judicial harmonisation and; (3) legislative harmonisation by means of EU Directives....
-
Two-spinors, oscillator algebras, and qubits: aspects of manifestly covariant approach to relativistic quantum information
PublicationThe first part of the paper reviews applications of 2-spinor methods to relativistic qubits (analogies between tetrads in Minkowski space and 2-qubit states, qubits defined by means of null directions and their role for elimination of the Peres-Scudo-Terno phenomenon, advantages and disadvantages of relativistic polarization operators defined by the Pauli-Lubanski vector, manifestly covariant approach to unitary representations...
-
Metody doboru miejsc zainstalowania zasobników energii w sieciach elektroenergetycznych niskiego napięcia
PublicationW związku z rosnącą liczbą źródeł odnawialnych przyłączanych do sieci niskiego napięcia (nn) jakość energii elektrycznej w tej sieci ulega pogorszeniu. Jedną z metod jej poprawiania jest instalowanie zasobników energii, tj. baterii akumulatorów, superkondensatorów czy kół zamachowych. Zasobniki energii są w stanie złagodzić dobową zmienność obciążenia, skompensować moc bierną i wyższe harmoniczne oraz zmniejszyć asymetrię obciążenia...
-
Experimental test results of the 150kVA 18-pulse diode rectifier with series active power filter
PublicationThe paper presents the control system and selected results of experimental tests of the ac/dc power converter consisting of 18-pulse diode rectifier on the basis of coupled reactors and a serial active power filter. Three configurations of the 150kVA converter were tested experimentally and compared: 18-pulse diode rectifier with and without additional grid reactor and the rectifier integrated with the active power filter. The...
-
Slow-wave resonant structures in branch-line coupler miniaturization: a case study
PublicationA case study of novel slow-wave resonant structures dedicated to efficient microstrip branch-line coupler size reduction has been presented. A compact 3-dB branch-line coupler has been designed to mimic the performance of its conventional counterpart, simultaneously demonstrating a substantial 88% surface area reduction. The vital usefulness of the approach in the process of microstrip line abbreviation has been experimentally...
-
Comparison of natural frequencies of a circular saw blade obtained empirically and with FEM
PublicationThe knowledge of the natural frequencies’ values of circular saw blades is necessary to determine the minimal critical rotational speed in which they can work with required stability. Moreover, testing the circular saw blades with more complicated shapes, e.g. which have additional holes inside blades for cleaning knifes or additional indirect teeth in gullets, reveals some kind of problematic properties of these saw blades. The...
-
Hybrid stepless distribution transformer with four-quadrant AC/DC/AC converter at low voltage side - simulation tests
PublicationThe article presents the work of the stepless hybrid distribution transformer (HT), as an alternative to the so far applied Automatic Voltage Regulator (AVR) solutions, used to control the voltage in the power system in terms of the fundamental harmonic. The HT is a combination of a conventional distribution transformer and an AC/DC/AC converter connected in series with the transformers secondary winding. In the work the basic...
-
Searching for Critical Conditions During Lifeboat Launching – Simulations
PublicationThe article describes numerical simulations of the process of lifeboat launching at the ship’s side. The research is aimed at finding the values of ship motion parameters which appear to be most dangerous for people in the lowered lifeboat due to the generated accelerations. The simplified model of ship hull motion adopted at this research stage bases on a superposition of harmonic motions with given amplitudes and periods in six...
-
Five-phase squirrel-cage motor. Construction and drive properties
PublicationThis paper presents the simulation and experimental results of a five-phase squirrel-cage induction motor. The new machine has been designed to operate in a drive system with third harmonic rotor flux injection in order to improve the motor torque utilization. The motor structure, the mathematical model as well as the laboratory prototype have been described. The motor speed-torque characteristics and transients are elaborated...
-
Power electronic transformer based on cascaded H-bridge converter
PublicationIn this paper the control strategy of power electronic transformer (PET) is proposed. The analyzed structure of PET uses two seven-level cascaded H-bridge (CHB) rectifiers. The electrical power of PET is transferred between DC-links of CHB converters using dual-active-bridges (DABs) and low voltage high frequency transformers. The roposed solution allows for controlling the active and reactive power with a low level of harmonic...
-
Analysis of Vibration and Acoustic Signals for Noncontact Measurement of Engine Rotation Speed
PublicationThe non-contact measurement of engine speed can be realized by analyzing engine vibration frequency. However, the vibration signal is distorted by harmonics and noise in the measurement. This paper presents a novel method for the measurement of engine rotation speed by using the cross-correlation of vibration and acoustic signals. This method can enhance the same frequency components in engine vibration and acoustic signal. After...
-
International architectural - urban - landscape design workshops to strengthen students’ education, capabilities and mobility
PublicationFive international architectural/urban/landscape workshops in Poland and Portugal between 2011 and 2015 are discussed in this article. The general aims of the workshops were to plan to connect divided city spaces, to harmonise them and make them attractive for different uses. The main task was to create in multicultural groups of students the vision of sustainable development in the context of architecture, urban and landscape...
-
Nonlinear impedance in oxide glasses containing single and mixed alkali ions
PublicationThe aim of the present was to find more clues on the nonlinearities in impedance of oxide glasses. The first family of researched glasses has a composition of FeO-P2O5-Na2O. Oxide glasses containing iron and alkali are well known for a very low alkali ion mobility and may be considered purely polaron conducting. These glasses show no detectable nonlinearities in the impedance spectra. The second was a family of ionic conducting...
-
Nonlinear Impedance as Possible Result of Ion-Polaron Interaction in Cu2O-Al2O3-SiO2 Glass
PublicationNonlinear a.c. impedance measurements were performed in Cu2O-Al2O3-SiO2 glass in wide frequency range. The obtained results shows that a large nonlinearity in the impedance signal is observed at moderate electric fields of an order 1V/mm. The contents of the third harmonics reaches about 10% and strongly depends on temperature and frequency. The investigated glass exhibits mixed electronic-ionic conductivity. Electronic conduction...
-
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...
-
Kompleksy metali przejściowych zawierające ligand R2P-P
PublicationBadania obejmują kompleksy metali przejściowych zawierające ligandy fosfanylofosfinidenowe oraz fosfanylofosfidowe. Kompleksy te są pochodnymi kompleksów fosfinidenowych oraz fosfidowych, gdzie grupa alkilowa została zastąpiona grupą fosfanylową (R’2P). W pracy można wydzielić trzy główne obszary badań. Pierwszym było zbadanie reaktywności R2PP(SiMe3)Li względem diamidowych bądź β-diketiminowych kompleksów cyrkonu zawierających...
-
Faults and Fault Detection Methods in Electric Drives
PublicationThe chapter presents a review of faults and fault detection methods in electric drives. Typical faults are presented that arises for the induction motor, which is valued in the industry for its robust construction and cost-effective production. Moreover, a summary is presented of detectable faults in conjunction with the required physical information that allow a detection of specific faults. In order to address faults of a complete...
-
Acoustic Hysteresis in Flows with Different Kinds of Relaxation and Attenuation
PublicationGraphs in the thermodynamic plane acoustic pressure versus excess acoustic density representing acoustic hysteresis, are considered as indicators of relaxation processes, equilibrium parameters of a flow, and kinds of wave exciters. Some flows with deviation from adiabaticity are examined: the Newtonian flow of a thermocon- ducting gas, the flow of a gas with vibrational relaxation, the flow of liquid electrolyte with a chemical...
-
Nonlinear Interaction of Magnetoacoustic Modes in a Quasi-Isentropic Plasma Flow
PublicationThe nonlinear interaction of magnetoacoustic waves in a plasma is analytically studied. A plasma is an open system. It is affected by the straight constant equilibrium magnetic flux density forming constant angle with the wave vector which varies from 0 till . The nonlinear instantaneous equation which describes excitation of secondary wave modes in the field of intense magnetoacoustic perturbations is derived by use of projecting....
-
Polyarmonic model of synchronous generator for analysis of autonomous power generation systems
PublicationAbstract: This paper presents the polyharmonic modelling of synchronous generator (SG) in machine variables. The simple geometry and windings physical layout has been used for inductance calculations of a salient-pole SG. The main advantage of this model is the ease of describing an autonomous power generation system (APGS) in terms of its topology and thus providing effective analysis at the static and dynamic states, both for...
-
Voltage Transients Transfer over Medium Voltage Instrument Transformers
PublicationThis paper presents voltage harmonic transfer accuracy problems through voltage transformers which are used in power quality monitoring systems in medium and high voltage grids. A simplified lumped parameters circuit model of the voltage transformer is proposed and verified by simulation and experimental investigations. A number voltage transformers typically used in medium voltage grid has been tested in the conducted disturbances...
-
Power Electronic Transformer For Smart Grid Application
PublicationIn this paper the control system of Power Electronic Transformer (PET) for the Smart Grid application is proposed. The structure of PET is based on two Cascaded H-bridge (CHB) converters. The electrical energy is transferred between converters using Dual-Active-Bridges (DAB) and high-frequency transformers. This type of coupling has been used to connect the DC-links of all H-bridges. The proposed control system for PET makes it...
-
Nonlinear Excitation of the Non-Wave Perturbations by the Magnetoacoustic Waves in the Non-Isentropic Plasma
PublicationNonlinear excitation of slow modes by the planar magnetosonic perturbations in a plasma is discussed. Plasma is an open system due to radiation and external heating. This may stipulate enhancement of wave perturbations and hence the acoustical activity of plasma. Plasma is assumed to be a homogeneous ideal gas with infinite electrical conductivity. The straight magnetic field is orthogonal to the velocity of fluid’s...
-
Zastosowanie modułu symulacji dynamicznej programu CAD w analizie układu napędowego elektronarzędzia
PublicationW referacie przedstawiono analizę mechanicznego układu przeniesienia napędu elektronarzędzia (wyrzynarki elektrycznej) przy zastosowaniu Modułu Symulacji Dynamicznej (MSD) programu Autodesk Inventor (AI). Opracowano modele 3D poszczególnych części elektronarzędzia i połączono je przy zachowaniu tzw. kinematyki odwrotnej. Przeprowadzono analizę wpływu poszczególnych węzłów kinetycznych na przebieg momentu na wale silnika elektrycznego....
-
Investigation of the temperature modulation parameters on semiconductor gas sensor response
PublicationIn this work we present the results of the investigation of the sensing properties of semiconductor gas sensors with a sinusoidally modulated temperature in the presence of synthetic air (SA) and three volatile air pollutants, i.e. NH3, NO2 and SO2. The measurements were performed for different average sensor heater temperatures and the amplitude of the modulation signal. In addition, the extraction of features from the sensor...
-
OGÓLNOPOLSKI PLENER ARTYSTYCZNY DOM KASZUBSKI NA ZIEMI ZABORSKIEJ. smaki dziedzictwa
PublicationPlener tematycznie dotyczył wysmakowanej architektury kaszubskiej na ziemi zaborskiej: domu kaszubskiego, zagrody i szerzej krajobrazu w kontekście tytułowych ‘smaków dziedzictwa’. Przedogródek, sad, ogród warzywny, pole, łąka, las i jezioro nadają smak życiu w kaszubskim domu. Ale rozumiejąc ‘smak dziedzictwa’ bardziej konceptualnie, karmimy zmysłu urokiem regionu, harmonią krajobrazu kulturowego i przyrodniczego oraz unikalną...
-
Experimental determination of dynamic properties of cylindrical steel tank model filled with liquid
PublicationIn technical branches, such as chemical or petroleum industries, cylindrical steel tanks are essential structures used for storage of liquid products. Any failure might have disastrous consequences, therefore their safety and reliability is essential. The aim of the present paper is to show the results of the experimental study which has been conducted on a scaled model of a real tank used in Poland. The investigation was carried...