Search
Search results for: SIGNAL PROPAGATION
-
DETECTION OF DEBONDING IN STEEL BARS EMBEDDED IN CONCRETE USING GUIDED WAVE PROPAGATION
PublicationThe paper presents a non-destructive diagnostic technique based on guided wave propagation phenomenon used to assess the adhesive bonding between a steel bar and a concrete cover. Double-layered cylindrical specimens with different levels of debonding and its location were investigated. The influence of bonding length on the excitation of multiple modes of longitudinal guided waves was analysed. Numerical simulations of guided...
-
Spectral Methods for Modelling of Wave Propagation in Structures in Terms of Damage Detection—A Review
PublicationModern methods of detection and identification of structural damage direct the activities of scientific groups towards the improvement of diagnostic methods using for example the phenomenon of mechanical wave propagation. Damage detection methods that use mechanical wave propagation in structural components are extremely effective. Many different numerical approaches are used to model this phenomenon, but, due to their universal...
-
Oriented Gaussian beams for high-accuracy computation with accuracy control of X-ray propagation through a multi-lens system
PublicationA highly accurate method for calculating X-ray propagation is developed. Within this approach, the propagating wave is represented as a superposition of oriented Gaussian beams. The direction of wave propagation in each Gaussian beam agrees with the local direction of propagation of the X-ray wavefront. When calculating the propagation of X-ray waves through lenses, the thin lens approximation is applied. In this approximation,...
-
An Empirical Propagation Model for Mobile Radio Links in Container Terminal Environment
PublicationIn this paper, a novel empirical propagation model for mobile radio links in a container terminal environment is presented. Measurement propagation research carried out in the Deepwater Container Terminal (DCT) in Gdańsk, Poland is described, and the investigated environment is characterized. The results of the statistical evaluation of the new model are discussed. In addition, statistical tuning of the Walfisch–Ikegami model for...
-
Wave propagation signals in concrete beams under 3-point bending
Open Research DataThe DataSet contains the results of the mechanical behaviour of a concrete beams with dimensions 40 x 40 x 160 cm3under the 3-point bending. The beams were made of concrete with the following ingredients: CEM I 42.5R (450 kg/m3), water (177 kg/m3), sand 0-2 (675 kg/m3) and gravel 2-8 (675 kg/m3). The bending test was performed using a Zwick/Roell Z10...
-
A Self-Adaptive Complex Root Tracing Algorithm for the Analysis of Propagation and Radiation Problem
PublicationAn improved complex root tracing algorithm for radiation and propagation issues is proposed. The approach is based on a self-adaptive discretization of Cauchy’s argument principle for a C × R space and requires a reduced number of function calls in comparison to other procedures presented in the literature. A few different examples concerning propagation and radiation problems have been considered to verify the validity and efficiency...
-
Self-refraction of acoustic pulses with shock fronts in some nonequilibrium media
PublicationThe 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...
-
Application of guided wave propagation in diagnostics of steel bridge components
PublicationEarly detection of potential defects and identification of their location are necessary to ensure safe, reliable and long-term use of engineering structures. Non-destructive diagnostic tests based on guided wave propagation are becoming more popular because of the possibility to inspect large areas during a single measurement with a small number of sensors. The aim of this study is the application of guided wave propagation in...
-
Waves Along Fractal Coastlines: From Fractal Arithmetic to Wave Equations
PublicationBeginning 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...
-
Metrological analysis of precision of the system of delivering a water capsule for explosive production of water aerosol
PublicationIn this paper an analysis of precision of the system controlling delivery by a helicopter of water-capsule designed for extinguishing large scale fires is presented. The analysis was performed using the numerical method of distribution propagation (Monte Carlo method) supplemented with results of application of the uncertainty propagation method. In addition the optimum conditions for the airdrop are determined to ensure achievement...
-
Reference-free determination of debonding length in reinforced concrete beams using guided wave propagation
PublicationThis paper presents theoretical and experimental investigations of guided wave propagation in reinforced concrete beams, with pre-existing debonding between steel rebars and concrete blocks, for the purpose of damage detection. The primary aim of these investigations was a detailed analysis of the possible applications of wave propagation in single and multiple debonding detection in reinforced concrete structures and reference-free...
-
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...
-
Experimental and numerical analysis of wave propagation in ground anchors
PublicationThe article focuses on wave propagation phenomenon in ground anchors. The main aim of the investigation is the non-destructive diagnostics and the assessment of the state of ground anchors, using the guided wave propagation method. Laboratory models of anchors with different lengths of the anchor body were tested and voltage signals of propagating waves were registered at several locations. For all tested specimens corresponding...
-
A high-accuracy method of computation of x-ray waves propagation through an optical system consisting of many lenses
PublicationThe propagation of X-ray waves through an optical system consisting of many X-ray refractive lenses is considered. Two differential equations are contemplated for solving the problem for electromagnetic wave propagation: first – an equation for the electric field, second – an equation derived for a complex phase of an electric field. Both equations are solved by the use of a finite-difference method. The simulation error is estimated...
-
Numerical analysis of elastic wave propagation in unbounded structures
PublicationThe main objective of this paper is to show the effectiveness and usefulness of the concept of an absorbing layer with increasing damping (ALID) in numerical investigations of elastic wave propagation in unbounded engineering structures. This has been achieved by the authors by a careful investigation of three different types of structures characterised by gradually increasing geometrical and mathematical description complexities....
-
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...
-
Modelling of Longitudinal Elastic Wave Propagation in a Steel Rod Using the Discrete Element Method
PublicationThe paper deals with the issue of modelling elastic wave propagation using the discrete element method (DEM). The case of a longitudinal wave in a rod with a circular cross-section was considered. A novel, complex algorithm consisting of the preparation of models and simulation of elastic waves was developed. A series of DEM models were prepared for simulations, differing in discretisation and material parameters. Additional calculations...
-
Discrete element method modelling of elastic wave propagation in a meso-scale model of concrete
PublicationThis paper deals with the accurate modelling of ultrasonic wave propagation in concrete at the mesoscopic level. This was achieved through the development of a discrete element method (DEM) model capable of simulating elastic wave signals comparable to those measured experimentally. The main objective of the work was to propose a novel methodology for constructing a meso-scale model of concrete dedicated to the analysis of elastic...
-
Modelling of elastic wave propagation in a bolted joint using a thin layer of shell elements
PublicationThere are many mathematical models describing the propagation of elastic waves through the imperfect boundary of two media. They were successfully applied to modelling of high frequency bulk waves and their interaction with local defects. On the other hand, the existing literature models of bolted connections ignore the aspect of imperfect connection between elements. Therefore, this paper presents the concept of application of...
-
Theoretical Model of Acoustic Wave Propagation in Shallow Water
PublicationThe work is devoted to the propagation of low frequency waves in a shallow sea. As a source of acoustic waves, underwater disturbances generated by ships were adopted. A specific feature of the propagation of acoustic waves in shallow water is the proximity of boundaries of the limiting media characterised by different impedance properties, which affects the acoustic field coming from a source situated in the water layer “ deformed”...
-
A higher order shell element for wave propagation in isotropic shell structures
PublicationThe presents the new multi mode higher order shell element for wave propagation problems in shell structures.
-
Inception and Propagation of Electrical Trees in the Presence of Space Charge in HVAC Extruded Cables
PublicationThis paper presents the space charge impact on the inception and propagation of electrical trees in cross-linked polyethylene (XLPE) insulation via simulations and experimentation. A 3D finite element analysis (FEA)-based modeling is proposed to simulate electrical trees via a needle embedded on the XLPE insulation. The proposed FEA model demonstrates the influence of the space charge magnitude and polarity on the initiation of...
-
Estimation of the uncertainty of the LEM CV 3-500 transducers processing function
PublicationThe 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,...
-
Diagnostics of historic columns using wave propagation
PublicationThis paper presents a numerical analysis of elastic wave propagation in columns of historical buildings for diagnostics purposes. Numerical calculations were performed using the finite element method in the Abaqus software package. The analysis was carried out for three types of brick columns: a full column, a column filled with debris, and a column empty inside. The excitation was in the form of a wave packet and signals of propagating...
-
Numerical FDM modelling of wave propagation in concrete structure
PublicationThe article presents application of finite difference method to damage detection and its size evaluation in concrete structure by elastic wave propagation method. The simulations of wave propagation in concrete structure were performed for six different damage scenarios. Damages were modelled as areas with changed material properties. Investigation focused on the influence of damage size on the energy of wave reflection. Presented...
-
Guided wave propagation in diagnostic of steel elements
PublicationThis paper is devoted to numerical investigations of elastic wave propagation in steel elements. The aim of this study is to conduct numerical analysis and experimental investigations on the propagation of elastic waves in steel elements in the context of damage detection. In particular, this paper is devoted to detection of damage occurring in the form of notch or changed thickness. This approach utilized the fact that any discontinuities...
-
Guided wave propagation in diagnostic of steel elements
PublicationThis paper is devoted to numerical investigations of elastic wave propagation in steel elements. The aim of this study is to conduct numerical analysis and experimental investigations on the propagation of elastic waves in steel elements in the context of damage detection. In particular, this paper is devoted to detection of damage occurring in the form of notch or changed thickness. This approach utilized the fact that any discontinuities...
-
Simulation of Wave Propagation in Media Described by Fractional-Order Models
PublicationIn this paper, algorithms for simulation of the wave propagation in electromagnetic media described by fractional-order (FO) models (FOMs) are presented. Initially, fractional calculus and FO Maxwell's equations are introduced. The problem of the wave propagation is formulated for media described by FOMs. Then, algorithms for simulation of the non-monochromatic wave propagation are presented which employ computations in the time...
-
About definition of modes and magnetosonic heating in a plasma’s flow: Especial cases of perpendicular and nearly perpendicular wave vector and magnetic field
PublicationDynamics 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...
-
Propagation analysis of the point-to-point radio links operating in the band
PublicationThe theoretical possibilities of utilizing the EHF-band frequencies for point-to-point short range communications have been discussed. The most important factors that affect propagation attenuation in this band have been briefly described, as well as relevant mathematical formulas that allow for numerical analysis of these phenomena. After that, a research have been carried out in which the authors have analyzed propagation losses...
-
Ultrasonic wave propagation and digital image correlation measurements of polyolefin fibre-reinforced concrete beams under 3-point bending (beam B-002)
Open Research DataThe DataSet contains the results of the mechanical behaviour of a concrete beam under a 3-point bending test. The beams had dimensions 15 x 15 x 70 cm3. The beam B-Con was made of concrete without fibres (as the reference beam), while beams B-002, B-004, and B-006 were manufactured from the concrete mix containing 2 kg/m3, 4 kg/m3 and 6 kg/m3 of fibres,...
-
Ultrasonic wave propagation and digital image correlation measurements of polyolefin fibre-reinforced concrete beams under 3-point bending (beam B-Con)
Open Research DataThe DataSet contains the results of the mechanical behaviour of a concrete beam under a 3-point bending test. The beams had dimensions 15 x 15 x 70 cm3. The beam B-Con was made of concrete without fibres (as the reference beam), while beams B-002, B-004, and B-006 were manufactured from the concrete mix containing 2 kg/m3, 4 kg/m3 and 6 kg/m3 of fibres,...
-
Ultrasonic wave propagation and digital image correlation measurements of polyolefin fibre-reinforced concrete beams under 3-point bending (beam B-004)
Open Research DataThe DataSet contains the results of the mechanical behaviour of a concrete beam under a 3-point bending test. The beams had dimensions 15 x 15 x 70 cm3. The beam B-Con was made of concrete without fibres (as the reference beam), while beams B-002, B-004, and B-006 were manufactured from the concrete mix containing 2 kg/m3, 4 kg/m3 and 6 kg/m3 of fibres,...
-
Ultrasonic wave propagation and digital image correlation measurements of polyolefin fibre-reinforced concrete beams under 3-point bending (beam B-006)
Open Research DataThe DataSet contains the results of the mechanical behaviour of a concrete beam under a 3-point bending test. The beams had dimensions 15 x 15 x 70 cm3. The beam B-Con was made of concrete without fibres (as the reference beam), while beams B-002, B-004, and B-006 were manufactured from the concrete mix containing 2 kg/m3, 4 kg/m3 and 6 kg/m3 of fibres,...
-
The finite difference methods of computation of X-rays propagation through a system of many lenses
PublicationThe propagation of X-ray waves through an optical system consisting of many beryllium X-ray refrac- tive lenses is considered. In order to calculate the propagation of electromagnetic in the optical sys- tem, two differential equations are considered. First equation for an electric field of a monochromatic wave and the second equation derived for complex phase of the same electric The propagation of X-ray waves through an optical system...
-
Reliable OFDM Data Transmission with Pilot Tones and Error-Correction Coding in Shallow Underwater Acoustic Channel
PublicationThe performance of Underwater Acoustic Communication (UAC) systems are strongly related to the specific propagation conditions of the underwater channel. Horizontal, shallow-water channels are characterised by extremely disadvantageous transmission properties, due to strong multipath propagation and refraction phenomena. The paper presents the results of communication tests performed during a shallow, inland-water experiment with...
-
Fast Fading Characterization for Body Area Networks in Circular Metallic Indoor Environments
PublicationWith the increasing development of 5G and Body Area Network based systems being implemented in unusual environments, propagation inside metallic structures is a key aspect to characterize propagation effects inside ships and other similar environments, mostly composed of metallic walls. In this paper, indoor propagation inside circular metallic structures is addressed and fast fading statistical distributions parameters are obtained...
-
Baseline-free debonding detection in reinforced concrete structures by elastic wave propagation
PublicationThe article presents the results of the numerical and experimental analysis concerning wave propagation in reinforced concrete (RC) beams with various extent of debonding between the steel rod and concrete cover. The main aim of the paper was to consider the unsolved research gaps, which considerably limit the application of wave-based methods in practice. The propagation of the flexural wave modes excited and registered on the...
-
Application of RMS for damage detection by guided elastic waves
PublicationThis 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.
-
Hybrid Method Analysis of Unshielded Guiding Structures
PublicationA 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...
-
Application of guided waves in the evaluation of steel-concrete adhesive connection
PublicationThe 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...
-
The study of acoustic climate of the Southern Baltic
PublicationThis 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...
-
Propagation of Ship-Generated Noise in Shallow Sea
PublicationContamination of sea environment by noise and any energy radiated to water constitutes today a problem to which more and more attention is paid, in view, a.o., of consequences of an impact of these factors onto marine fauna. European Union has introduced a directive by which EU countries are made responsible to undertake efforts aimed at reaching a good envirenmental status of European seas by 2020. A main source of underwater...
-
Unusual divergence of magnetoacoustic beams
PublicationTwo-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...
-
Non-destructive inspection of ground anchors using guided wave propagation
PublicationThis paper deals with numerical and experimental investigations of specific problems of guided wave propagation in ground anchors. The research focuses on recognizing the phenomenon of the energy transfer between anchor components. Particular attention is paid to characteristic features of guided waves propagating in free and embedded parts of the tendon, at the interface between the tendon and the surrounding anchor body as well...
-
High-accuracy computation of hard X-ray focusing and imaging for refractive optics
PublicationA 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...
-
Modification of Selected Propagation Models in Terms of Path Loss Estimation in Container Terminal
PublicationIt is particularly important to look for any propagation model that could be useful for designing mobile radio networks in container terminal environment. Selected propagation models have been investigated. Firstly - basing on measurements results - they have been evaluated in this scope and the analysis has shown, that the adjustment is needed. This modification improved significantly the accuracy of path loss modelling. For the...
-
Numerical modeling of GPR field in damage detection of a reinforced concrete footbridge
PublicationThe 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...
-
Wake-Up Receiver for Underwater Acoustic Communication Using in Shallow Water
PublicationA 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...
-
The propagation of the waves in the CTO S.A. towing tank
PublicationThe paper presents the results of research focused on the wave propagation in the CTO S.A. deepwater towing tank. In the scope of paper, the wavemaker transfer function was determined for regular waves, based on the Biésel Transfer Function and further for irregular waves, based on Hasselman model of nonlinear energy transfer. The phenomena: wave damping, wave breakdown and wave reflection, were measured, analyzed and mathematically...