wyświetlamy 1000 najlepszych wyników Pomoc
Wyniki wyszukiwania dla: RADIOWAVE PROPAGATION CONDITIONS
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Jacek Tomków dr hab. inż.
OsobyWykształcenie:1. 2018 r.Doktor inżynier - Politechnika Gdańska, Wydział Mechaniczny, Inżynieria Materiałowa,rozprawa doktorska: Wpływ warunków spawania pod wodą na skłonność do tworzenia pęknięć zimnych w stalach o podwyższonej wytrzymałości 2. 2012 r.Magister inżynier - Politechnika Gdańska, Wydział Mechaniczny, Mechanika i Budowa Maszyn, specjalność: Technologia Maszyn i Komputerowe Wspomaganie Produkcji,praca magisterska: Badania...
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Guided waves for nondestructive diagnostics of embedded waveguides
PublikacjaThe thesis concentrates on comprehensive theoretical, numerical and experimental analysis of guided wave propagation in bars embedded in concrete or mortar. The investigations are focused on a particular type of objects representing a laboratory model of a ground anchor. Complex description of wave propagation phenomena in partially embedded bars is given and its application in...
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The assessment of microbiological purity of cosmetic preparations
Dane BadawczeThe dataset contains the results of a single series of determinations of the microbiological purity of the cosmetic based on the aqueous phase in the test for the total number of bacteria and the total number of yeasts.The tests were performed by preparing a series of decimal dilutions of the cosmetic in peptone water and performing in-depth culture...
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Study of QoS Parameters Measurement Methodology and Requirements in RSMAD
PublikacjaThe paper presents the results of analysis and research of the quality of service requirements (defined by the QoS parameters) for data transmission services in Radio System for Monitoring and Acquisition of Data from Traffic Enforcement Cameras (in short: RSMAD). The paper also presents and discusses the results of test of impact of the size of images from traffic enforcement cameras (TECs) on the average transmission time. Moreover,...
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Radosław Drozd dr inż.
OsobyRadosław Drozd - Praktyk i wieloletni menedżer zarządzania inżynierskiego i logistyki inżynierskiej. Jest absolwentem Wydziału Zarządzania i Ekonomii PG na specjalności Organizacji systemów produkcyjnych. Jego zainteresowania naukowo-badawcze obejmują projektowanie oraz doskonalenie systemów produkcyjnych i logistycznych, a także rozwój innowacyjnych produktów. Uczestnicząc lub prowadząc projekty w wielu przedsiębiorstwach produkcyjnych...
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Analysis of Impulse Responses Measured in Motion in a Towing Tank
PublikacjaThe growing interest in developing autonomous underwater vehicles (AUVs) and creating underwater sensor networks (USNs) has led to a need for communication tools in underwater environments. For obvious reasons, wireless means of communication are the most desirable. However, conducting research in real conditions is troublesome and costly. Moreover, as hydroacoustic propagation conditions change very significantly, even during...
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Analysis of Impulse Responses Measured in Motion in a Towing Tank
PublikacjaThe growing interest in developing autonomous underwater vehicles (AUVs) and creating underwater sensor networks (USNs) has led to a need for communication tools in underwater environments. For obvious reasons, wireless means of communication are the most desirable. However, conducting research in real conditions is troublesome and costly. Moreover, as hydroacoustic propagation conditions change very significantly, even during...
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Corrosion damage identification based on the symmetry of propagating wavefield measured by a circular array of piezoelectric transducers: Theoretical, experimental and numerical studies
PublikacjaThe article investigates the results obtained from numerical simulations and experimental tests concerning the propagation of guided waves in corroded steel plates. Developing innovative methodologies for assessing corrosion-induced degradation is crucial for accurately diagnosing offshore and ship structures exposed to harsh environmental conditions. The main aim of the research is to analyze how surface irregularities affect...
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Influence of pulse waves on the transmission of near-infrared radiation in outer-head tissue layers.
PublikacjaIn this study, we investigate the effect of pulse waves on the transmission of near-infrared radiation in the outer tissue layers of the human head. This effect is important in using optical radiation to monitor brain conditions based on measuring the transmission changes in the near-infrared radiation between the source and the detector, placed on the surface of the scalp. This is because the signal related to the changes in the...
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Uniform sampling in constrained domains for low-cost surrogate modeling of antenna input characteristics
PublikacjaIn this letter, a design of experiments technique that permits uniform sampling in constrained domains is proposed. The discussed method is applied to generate training data for construction of fast replacement models (surrogates) of antenna input characteristics. The modeling process is design-oriented with the surrogate domain spanned by a set of reference designs optimized with respect to the performance figures and/or operating...
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Self-refraction of acoustic pulses with shock fronts in some nonequilibrium media
PublikacjaThe nonlinear self-refraction of acoustic pulsed beams, which include shock fronts, is studied. The medium of sound propagation is a gas where thermodynamically nonequilibrium processes take place, such as exothermic chemical reaction or excitation of vibrational degrees of a molecule’s freedom. Comparative analysis of the features of sound propagation over gases where pure nonlinear attenuation of the shock wave occurs, and gases...
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Low-cost data-driven modelling of microwave components using domain confinement and PCA-based dimensionality reduction
PublikacjaFast data-driven surrogate models can be employed as replacements of computationally demanding full-wave electromagnetic simulations to facilitate the microwave design procedures. Unfortunately, practical application of surrogate modelling is often hindered by the curse of dimensionality and/or considerable nonlinearity of the component characteristics. This paper proposes a simple yet reliable approach to cost-efficient modelling...
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Waves Along Fractal Coastlines: From Fractal Arithmetic to Wave Equations
PublikacjaBeginning with addition and multiplication intrinsic to a Koch-type curve, we formulate and solve wave equation describing wave propagation along a fractal coastline. As opposed to examples known from the literature, we do not replace the fractal by the continuum in which it is embedded. This seems to be the first example of a truly intrinsic description of wave propagation along a fractal curve. The theory is relativistically...
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Theory of architectural design IV_ERASMUS
Kursy OnlineThe Theory of architectural design IV ERASMUS is a course dedicated especially to Erasmus+ students and conducted on separate conditions.
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Acoustic field and the entropy mode induced by it in a waveguide filled with some non-equilibrium gases
PublikacjaThe 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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Rapid Variable-Resolution Parameter Tuning of Antenna Structures Using Frequency-Based Regularization and Sparse Sensitivity Updates
PublikacjaGeometry parameter tuning is an inherent part of antenna design process. While most often performed in a local sense, it still entails considerable computational expenses when carried out at the level of full-wave electromagnetic (EM) simulation models. Moreover, the optimization outcome may be impaired if good initial design is not available. This paper proposes a novel approach to fast and improved-reliability gradient-based...
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The Examination of the Upper Layers of the Seabed by the Means of the Acoustic Methods
PublikacjaPropagation of acoustic waves in the sea, in particular in shallow sea, depends on several factors. The basic of them are source power and frequency of acoustic waves, spatial distribution inhomogeneous medium in which acoustic wave propagates, and distributions of speed of sound and density of seawater. The coastal conditions, which limit water medium from above (free surface of the sea) and from bottom (the seabed), are no less...
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Modelling and simulations in time-fractional electrodynamics based on control engineering methods
PublikacjaIn this paper, control engineering methods are presented with regard to modelling and simulations of signal propagation in time-fractional (TF) electrodynamics. That is, signal propagation is simulated in electromagnetic media described by Maxwell’s equations with fractional-order constitutive relations in the time domain. We demonstrate that such equations in TF electrodynamics can be considered as a continuous-time system of...
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Estimation of the uncertainty of the LEM CV 3-500 transducers processing function
PublikacjaThe paper presents the methodology for estimating uncertainty of a voltage transducer processing function based on the example of LEM CV 3-500 transducer. The analysis was performed using the method based on the GUM Guide propagation of uncertainty law and the Monte Carlo numerical method. The article also presents a comparative analysis of the results of a voltage measurement evaluation done using the Monte Carlo simulation method,...
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Expedited Acquisition of Database Designs for Reduced-Cost Performance-Driven Modeling and Rapid Dimension Scaling of Antenna Structures
PublikacjaFast replacement models have been playing an increasing role in high-frequency electronics, including the design of antenna structures. Their role is to improve computational efficiency of the procedures that normally entail large numbers of expensive full-wave electromagnetic (EM) simulations, e.g., parametric optimization or uncertainty quantification. Recently introduced performance-driven modeling methods, such as the nested...
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Dawid Ryś dr hab. inż.
OsobySZKOLENIA Szkolenie dotyczące metodyki zarządzania projektami PRINCE 2. Certyfikat kwalifikacji. Szkolenie dotyczące Mikromechaniki Pracy Mieszanek Mineralno-Asfaltowych Szkolenie doyczące interakcji koło pojazdu-nawierzchnia
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Numerical modelling of POC dynamics in the southern Baltic under possible future conditions determined by nutrients, light and temperature**The study was financially supported by the Polish Ministry of Science and Higher Education (grants: NN305 111636 and NN306 404338) and Baltic-C – the BONUS funded project.
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About definition of modes and magnetosonic heating in a plasma’s flow: Especial cases of perpendicular and nearly perpendicular wave vector and magnetic field
PublikacjaDynamics of hydrodynamic perturbations in a plasma depend strongly on an angle between the wave vector and equilibrium straight magnetic field. The case of perpendicular propagation is especial. There are only two (fast) magnetosonic modes since two (slow) ones degenerate into the stationary one with zero speed of propagation. This demands individual definition of wave modes by the links of hydrodynamic relations. These links are...
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Daylight evaluation for multi-family housing in Poland
PublikacjaThis PhD dissertation focuses on methods of daylight appraisal useful in the design of the contemporary multifamily housing. The theoretical part of the thesis offers a review of daylight indicators, evaluations methods and tools within the built environment. It covers a review of daylight recommendations found in building standards and other normative documents affecting the design of the residential spaces. A pilot work survey...
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On nonlinear dilatational strain gradient elasticity
PublikacjaWe call nonlinear dilatational strain gradient elasticity the theory in which the specific class of dilatational second gradient continua is considered: those whose deformation energy depends, in an objective way, on the gradient of placement and on the gradient of the determinant of the gradient of placement. It is an interesting particular case of complete Toupin–Mindlin nonlinear strain gradient elasticity: indeed, in it, the...
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Filter-Hilbert Method for Automatic Correction of Non-Anechoic Antenna Measurements with Embedded Self-Calibration Mechanism
PublikacjaOne of the most important steps in the process of antenna development involves measurements of its prototype. Far-field performance of radiators is normally characterized in strictly controlled environments such as anechoic chambers which can ensure certification-grade accuracy. Unfortunately, they are also characterized by high construction costs which might not be justified for low-budget research and/or teaching-related activities....
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Quality Model for Integrated Security Monitoring and Control in Water Distribution Systems
PublikacjaThis article addresses the problem of drinking water distribution system (DWDS) security in the terms of water quality which in the era of terrorist threat is of high importance to the public. The contribution of this paper is the development of the so called security module to extend a multi-species water quality model. This gives an insight to the situation in DWDS not only under normal operational conditions but also in case...
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Limitations of WSSUS modeling of stationary underwater acoustic communication channel
PublikacjaPerformances of underwater acoustic communication (UAC) systems are strongly related to specific propagation conditions of the underwater channel. Due to their large variability, there is a need for adaptive matching of the UAC systems signaling to the transmission properties of the channel. This requires a knowledge of instantaneous channel characteristics, in terms of the specific parameters of stochastic models. The wide-sense...
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Testing the Wide-Sense Stationarity of Bandpass Signals for Underwater Acoustic Communications
PublikacjaThe Underwater Acoustic Communication (UAC) systems work in communication channels characterized by a large variety of multipath propagation conditions that can additionally change over time. Designing a reliable communication system requires knowledge of the transmission parameters of the channel. There is a need for the development of adaptive signaling schemes that would dynamically optimize the signal parameters of the physical...
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Au–Si plasmonic platforms: synthesis, structure and FDTD simulations
PublikacjaPlasmonic platforms based on Au nanostructures have been successfully synthesized by directional solidification of a eutectic from Au and the substrate. In order to determine homogeneous shape and space distribution, the influence of annealing conditions and the initial thickness of the Au film on the nanostructures was analyzed. For the surface morphology studies, SEM and AFM measurements were performed. The structure of platforms...
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LOS and NLOS identification in real indoor environment using deep learning approach
PublikacjaVisibility conditions between antennas, i.e. Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) can be crucial in the context of indoor localization, for which detecting the NLOS condition and further correcting constant position estimation errors or allocating resources can reduce the negative influence of multipath propagation on wireless communication and positioning. In this paper a deep learning (DL) model to classify LOS/NLOS...
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Improved-Efficacy EM-Driven Optimization of Antenna Structures Using Adaptive Design Specifications and Variable-Resolution Models
PublikacjaOptimization-driven parameter tuning is an essential step in the design of antenna systems. Although in many cases it is still conducted through parametric studies, rigorous numerical methods become a necessity if truly optimum designs are sought for, and the problem intricacies (number of variables, multiple goals, constraints) make the interactive approaches insufficient. The two practical considerations of electromagnetic (EM)-driven...
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Application of RMS for damage detection by guided elastic waves
PublikacjaThis paper presents certain results of an experimental study related with a damage detection in structural elements based on deviations in guided elastic wave propagation patterns.
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Analysis of Methods for Determining Shallow Waterbody Depths Based on Images Taken by Unmanned Aerial Vehicles
PublikacjaHydrographic surveys enable the acquisition and processing of bathymetric data, which after being plotted onto nautical charts, can help to ensure safety of navigation, monitor changes in the coastal zone, and assess hydro-engineering structure conditions. This study involves the measurement of waterbody depth, identification of the seabed shape and geomorphology, the coastline course, and the location of underwater obstacles....
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Application of guided waves in the evaluation of steel-concrete adhesive connection
PublikacjaThe aim of the paper is the application of guided waves in the evaluation of a condition state of adhesive connection between steel and concrete. The study concerns a push-out specimen consisting of two steel plates glued to opposite faces of a concrete cube with the use of structural adhesive. Wave propagation in the specimen without external load is investigated both experimentally and numerically. The second stage of the investigation...
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The study of acoustic climate of the Southern Baltic
PublikacjaThis paper presents the statistical characteristics of seawater properties, which are necessary for predicting the propagation of acoustic waves in selected areas of the Baltic Sea. The statistics were elaborated based on long-term measurements of vertical distributions of sound speed, temperature, and salinity, and the nonlinearity parameter B/A. Nonlinear properties of the environment are considered, in connection...
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Hybrid Method Analysis of Unshielded Guiding Structures
PublikacjaA combination of mode matching, finite element methods and generalized impedance matrix is presented in a context of propagation problems for open guiding structures. The computational domain is divided into two regions: the first one is a circular cylinder containing whole guiding structure and the second one surrounds this artificial cylinder. The impedance matrix is calculated with the use of finite element method in the first...
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Broadband communication solutions for maritime ITSs: Wider and faster deployment of new e-navigation services
Publikacjan its initial part, the paper presents an overview of popular technologies and systems currently developed or employed in maritime communication. These solutions are used to provide both ship-to-ship and ship-to-shore communication for the purpose of supporting specific services, often dedicated to maritime safety and e-navigation. Utility of such communication systems have been thoroughly verified over the years and their strengths...
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Assessment of Wide-Sense Stationarity of an Underwater Acoustic Channel Based on a Pseudo-Random Binary Sequence Probe Signal
PublikacjaThe performances of Underwater Acoustic Communication (UAC) systems are strongly related to the specific propagation conditions of the underwater channel. Designing the physical layer of a reliable data transmission system requires a knowledge of channel characteristics in terms of the specific parameters of the stochastic model. The Wide-Sense Stationary Uncorrelated Scattering (WSSUS) assumption simplifies the stochastic description...
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Ocena odporności powłok na bazie DLC na doraźne uszkodzenie w warunkach tarcia ślizgowego ze smarowaniem wodą i solą fizjologiczną = Evaluation of DLC based coatings resistance to instanteneous damage under sliding friction conditions with distilated water or saline lubrication
PublikacjaWykonano serię testów w celu wyznaczenia granicznych warunków wymuszenia, zdefiniowaego jako średnie naciski powierzchniowe oraz prędkość ślizgania, po przekroczeniu których następuje gwałtowne zniszczenie powłoki. Na podstawie wyników pomiarów opracowano aproksymowane charakterystyki granicznych wymuszeń w układzie p - v oraz pokrewnych dla badanych materiałów, smarów i zakresu parametrów wymuszenia.
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The study on possibilities of recovery non-magnetic fraction by utilisation the magnetic separation technology in conditions of KGHM Polska Miedz S.A. division of concentrators = Próby odzysku frakcji niemagnetycznej metodą separacji magnetycznej w warunkach KGHM Polska Miedź S.A. Oddział Zakłady Wzbogacania Rud
PublikacjaW referacie przybliżono wyniki badań prowadzonych w kierunku określenia możliwości odzysku frakcji niemagnetycznej i słabomagnetycznej ze strumieni materiałowych O/ZWR, poprzez wykorzystanie metody separacji magnetycznej. Przeprowadzony cykl badawczy obejmował analizę występowania frakcji magnetycznej i związanej z nią frakcji niemagnetycznej w obiegach technologicznych w Rejonie ZWR Lubin, oraz możliwości ich odzysku. Uzyskane...
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Unusual divergence of magnetoacoustic beams
PublikacjaTwo-dimensional magnetosonic beams directed along a line forming a constant angle h with the equilibrium straight magnetic field are considered. Perturbations in a plasma are described by the system of ideal magnetohydrodynamic equations. The dynamics of perturbations in a beam are different in the cases of fast and slow modes, and it is determined by h and equilibrium parameters of a plasma. In particular, a beam divergence may...
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Numerical modeling of GPR field in damage detection of a reinforced concrete footbridge
PublikacjaThe paper presents a study on the use of the ground penetrating radar (GPR) method in diagnostics of a footbridge. It contains experimental investigations and numerical analyses of the electromagnetic field propagation using the finite difference time domain method (FDTD). The object of research was a reinforced concrete footbridge over a railway line. The calculations of the GPR field propagation were performed on a selected cross-section...
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High-accuracy computation of hard X-ray focusing and imaging for refractive optics
PublikacjaA mathematical apparatus for solving problems of X-ray wave propagation through complex optical systems, when the lens thickness can change with jumps, is developed and presented. The developed method is based on the use of the superposition of oriented Gaussian beams, which satisfy the Helmholtz equation with high accuracy. The wave propagation in air and through kinoform and ordinary lenses is considered. Focusing and imaging...
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Wake-Up Receiver for Underwater Acoustic Communication Using in Shallow Water
PublikacjaA data frame transmitted over the underwater acoustic channel usually begins with a preamble. Therefore, underwater communication systems have a dedicated receiver that constantly listens to the preamble signals. A receiver that is to work effectively in shallow waters must have solutions that effectively reduce the impact of the permanently occurring multipath propagation. The article presents a solution based on complementary...
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Fatigue Bending of V-Notched Cold-Sprayed FeCoCrNiMn Coatings
PublikacjaCold-spray coatings were produced by FeCoCrNiMn high-entropy alloy powders deposited on carbon steel substrate. The coatings were realized at intermediate temperature and high pressure (at 1100 °C and 7 MPa). The coating microstructure was characterized by scanning electron microscopy and X-ray diffraction, revealing a very dense deposition and high flattening ratio of the splatted particles. This had a large influence on the...
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Two tests for adhesive bonding long term characterization: principles and applications
PublikacjaThis article describes recent refinement of the traditional wedge test technique used to characterize durability of the adhesive joints. We propose two types of measuring protocols to monitor precisely and continuously the propagation of an "effective" crack during long term mode I fracture mechanic test. First method is directly derived from the traditional wedge test technique and consist in monitoring the surface strain of adherent...
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Hysteresis curves and loops for harmonic and impulse perturbations in some non-equilibrium gases
PublikacjaEvolution of sound in a relaxing gas whose properties vary in the course of wave propagation, is studied. A relaxing medium may reveal normal acoustic properties or be acoustically active. In the first case, losses in acoustic energy lead to an increase in internal energy of a gas similarly as it happens in Newtonian fluids. In the second case, acoustic energy increases in the course of sound propagation, and the internal energy...
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The conducted EMI in DC-DC converters
PublikacjaThis book presents the phenomena of conducted electromagnetic interference (EMI) generation in DC-DC converters. The measurement and simulation are used to analyze the impact of the most important parameters on the character, level and propagation path of interference. In this book, the analysis of the interference generation and propagation is presented on the example of three basic converters. The wide banded behavior of all...
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Elastic waves in the railroad track substructures and its surroundings analyzed with non-classical operational methods
PublikacjaWe analyze the propagation of the waves generated by the rolling stock and the interaction of those waves on the medium and its surroundings. We use non-classical operational methods for monitoring construction of the railway infrastructure and for noise damping.