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Search results for: ACOUSTIC WAVEFIELD EQUATIONS
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Parameter and delay estimation of linear continuous-time systems
PublicationIn this paper the problem of on-line identification of non-stationary delay systems is considered. Dynamics of supervised industrial processes is described by ordinary differential equations. Discrete-time mechanization of their continuous-time representations is based on dedicated finite-horizon integrating filters. Least-squares and instrumental variable procedures implemented in recursive forms are applied for simultaneous identification...
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New Approach to Arc Fitting for Railway Track Realignment
PublicationThis article presents a new method of arc fitting for railway track realignment. The theoretical foundations are presented, along with a detailed algorithm of the iterative computational process. This method is based on solving a set of linearized pseudo-observation equations. The formulas of the functional model of the fitting problem were derived, and a special form of objective function is proposed. An iterative method for optimization...
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On Dynamic Boundary Conditions Within the Linear Steigmann-Ogden Model of Surface Elasticity and Strain Gradient Elasticity
PublicationWithin the strain gradient elasticity we discuss the dynamic boundary conditions taking into account surface stresses described by the Steigmann–Ogden model. The variational approach is applied with the use of the least action functional. The functional is represented as a sum of surface and volume integrals. The surface strain and kinetic energy densities are introduced. The Toupin–Mindlin formulation of the strain gradient elasticity...
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On the correspondence between two- and three-dimensional Eshelby tensors
PublicationWe consider both three-dimensional (3D) and two-dimensional (2D) Eshelby tensors known also as energy–momentum tensors or chemical potential tensors, which are introduced within the nonlinear elasticity and the resultant nonlinear shell theory, respectively. We demonstrate that 2D Eshelby tensor is introduced earlier directly using 2D constitutive equations of nonlinear shells and can be derived also using the throughthe-thickness...
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On dynamics of origami-inspired rod
PublicationWe discuss the dynamics of a relatively simple origami-inspired structure considering discrete and continuum models. The latter was derived as a certain limit of the discrete model. Here we analyze small in-plane deformations and related equations of infinitesimal motions. For both models, dispersion relations were derived and compared. The comparison of the dispersion relations showed that the continuum model can capture the behavior...
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Database of the illustrative simulations of the nonstandard approximation of the generalized Burgers–Huxley equation
Open Research DataThe presented dataset is a result of numerical analysis of a generalized Burgers–Huxley partial differential equation. An analyzed diffusive partial differential equation consist with nonlinear advection and reaction. The reaction term is a generalized form of the reaction law of the Hodgkin–Huxley model, while the advection is a generalized form of...
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Communication Platform for Evaluation of Transmitted Speech Quality
PublicationA voice communication system designed and implemented is described. The purpose of the presented platform was to enable a series of experiments related to the quality assessment of algorithms used in the coding and transmitting of speech. The system is equipped with tools for recording signals at each stage of processing, making it possible to subject them to subjective assessments by listening tests or, objective evaluation employing...
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Przegląd metod pomiaru temperatury przewodów linii napowietrznych wysokiego napięcia
PublicationW artykule przedstawiono przegląd metod pomiaru temperatury napowietrznych linii wysokiego napięcia stosowanych w celu poprawy niezawodności eksploatacji i w celu wyznaczania dopuszczalnej obciążalności linii. Omówiono system DOL dynamicznej obciążalności linii oraz bezdotykowe metody pomiaru temperatury: pomiar z użyciem pasywnych czujników SAW (ang. Surface acoustic wave sensor), DTS (distributed temperature sensing) z wykorzystaniem...
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Multibeam Sonar Data Processing for Seafloor Classification
PublicationDespite many years of the development of methodology for sensing the seafloor by means of underwater acoustics, the currently used techniques are still not mature enough and not ready to be utilised in numerous different (i.e. with respect to a water region character, used equipment type etc.) tasks. Therefore the hydroacoustic methods, both utilising vertical observations (e.g. by singlebeam echosounders), as well as those relying...
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Strong ellipticity conditions and infinitesimal stability within nonlinear strain gradient elasticity
PublicationWe discuss connections between the strong ellipticity condition and the infinitesimal instability within the nonlinear strain gradient elasticity. The strong ellipticity (SE) condition describes the property of equations of statics whereas the infinitesimal stability is introduced as the positive definiteness of the second variation of an energy functional. Here we establish few implications which simplify the further analysis...
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Analytical method of modelling the geometric system of communication route
PublicationThe paper presents a new analytical approach to modelling the curvature of a communication route by making use of differential equations. The method makes it possible to identify both linear and nonlinear curvature. It enables us to join curves of the same or opposite signs of curvature. Solutions of problems for linear change of curvature and selected variants of nonlinear curvature in polynomial and trigonometric form were analyzed....
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Parameter and delay estimation of linear continuous-time systems
PublicationIn this paper the problem of on-line identification of non-stationary delay systems is considered. Dynamics of supervised industrial processes is usually described by ordinary differential equations. Discrete-time mechanization of their continuous-time representations is based on dedicated finite-horizon integrating filters. Least-squares and instrumental variable procedures implemented in recursive forms are applied for simultaneous...
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On–line Parameter and Delay Estimation of Continuous–Time Dynamic Systems
PublicationThe problem of on-line identification of non-stationary delay systems is considered. The dynamics of supervised industrial processes are usually modeled by ordinary differential equations. Discrete-time mechanizations of continuous-time process models are implemented with the use of dedicated finite-horizon integrating filters. Least-squares and instrumental variable procedures mechanized in recursive forms are applied for simultaneous...
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Multi-headed chimera states in coupled pendula
PublicationWe discuss the occurrence of the chimera states in the network of coupled, excited by the clock’s mechanisms pendula. We find the patterns of multi-headed chimera states in which pendula clustered in different heads behave differently (oscillate with different frequencies) and create different types of synchronous states (complete or phase synchronization). The mathematical model of the network shows that the observed chimera states...
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Research on the wear evenness of the tool in flat lapping
PublicationIn this paper, the dimensionless distribution of the material removal stock and the trajectories of abrasive grains cutting in single-sided lapping process are presented. They were numerically simulated based on the tribological model and kinematics equations. It can be observed that the trajectories geometry of single abrasive as well the velocities have a great influence on the final geometrical deviation. During machining, the...
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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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Identification of Parameters Influencing the Accuracy of the Solution of the Nonlinear Muskingum Equation
PublicationTwo nonlinear versions of the Muskingum equation are considered. The difference between both equations relates to the exponent parameter. In the first version, commonly used in hydrology, this parameter is considered as free, while in the second version, it takes a value resulting from the kinematic wave theory. Consequently, the first version of the equation is dimensionally inconsistent, whereas the proposed second one is consistent. It...
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Viscous versus electromagnetic damping – amplification in a neighbourhood of a mechanism singular position
PublicationIn the paper, damping of vibrations are considered and compared in a mechanical and in a electromechanical system. In the system, a continuous beam is considered as the main vibrating element. The compared dissipations methods are based on: viscous dampers and DC generators. To increase the possible damping effectiveness, velocity amplification is proposed, i.e., a mechanism is introduced between the beam and the damping element....
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An Experimental and Numerical Analysis of Water Hammer Phenomenon in Slurries
PublicationThe analysis of slurry transportation in pressure pipelines is important both from practical and theoretical point of view. Due to the nature of the medium, the number of problems arising in the course of design, operation, measurements and mathematical modeling is much higher compared to the cases where the flowing liquid is homogeneous. The equations describing the flow are more complex, and higher number of the parameters is...
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Natural convective heat transfer from isothermalconic
PublicationTheoretical considerations on convective heat transfer from isothermal upward conicalsurfaces have been presented. The physical model of this phenomenon consists of an isothermalcone of inclination angle (φ) between the cone generating line (X) and the radius (R) of the cone base. The angle is a parameter of conical surface which varied from (φ = 0−circular horizontal plate) to (φ = π/2—vertical cylinder) . Onthe basis of Navier–Stokes...
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Nonlinear free and forced vibrations of a dielectric elastomer-based microcantilever for atomic force microscopy
PublicationThe majority of atomic force microcode (AFM) probes work based on piezoelectric actuation. However, some undesirable phenomena such as creep and hysteresis may appear in the piezoelectric actuators that limit their applications. This paper proposes a novel AFM probe based on dielectric elastomer actuators (DEAs). The DE is modeled via the use of a hyperelastic Cosserat model. Size effects and geometric nonlinearity are included...
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On analysis of nanocomposite conical structures
PublicationThis research examines the analysis of rotating truncated conical baskets reinforced by carbon nanotubes around the two independent axes. A time-dependent analysis is considered, and the nonlinear dynamic governing equations are extracted using the energy method. Carbon nanotubes (CNTs) reinforced the conical basket, and the structure's mechanical properties are determined based on the several distributions of carbon nanotubes....
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Urban flash flood hazard identification and assessment applying geospatial techniques and hydrodynamic modeling; Erbil city case study, Kurdistan Region of Iraq
PublicationThis dissertation aims to investigate the factors behind flash flooding in Erbil's central district, located in the Kurdistan Region of Iraq, and develop a methodology for assessing flood hazards in the city, despite limited data accessibility. In this thesis, each factor was investigated, including analyzing extreme precipitation events in the last two decades, including their spatial and temporal distribution of rainfall, intensity,...
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Sound Field Intensity Measurements and Visualization around the Human Head Model . Rozkłąd natężenia pola akustycznego w komorze bezechowej obecności sztucznej głowy i w przypadku braku jej obecności
PublicationThe main goal of this research study was to measure and visualize sound field intensity distribution in and without presence of the human head model. Measurements were performed in the anechoic chamber with the 5 cm grid. Experimental setup consisted of a multitone generator, two loudspeakers, human head model, intensimetric probe, the Cartesian robot applied for precise positioning of the acoustic sensor, and an analyzer. Based...
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Analiza i ocena smarności olejów w ujęciu energetycznym i działania układu tribologicznego = Analysis and evaluation of oil lubricity from the viewpoint of energy apects and of the tribological system action
PublicationBased on measurement results, an interpretation is presented of the tribological system boundary layer action in the form of a four-ball tester friction node. The evaluation was performed of the boundary layer action understood as transfer of energy Ep resulting from loading the tribological system in a determined time t with work Lp, which may lead to breaking the boundary layer. That energy and time are the values unequivocally...
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Considerations about the applicability of the Reynolds equation for analyzing high-speed near field levitation phenomena
Publicationequation for analyzing near field levitation (NFL) phenomena. Two separate approaches were developed, experimentally verified, and applied to meet the research objective. One was based on the Reynolds equation and the other was based on general conservation equations for fluid flow solved using computational fluid dynamic (CFD). Comparing the calculation results revealed that, for certain operating conditions, differences in the...
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On Applications of Fractional Derivatives in Circuit Theory
PublicationIn this paper, concepts of fractional-order (FO) derivatives are discussed from the point of view of applications in the circuit theory. The properties of FO derivatives required for the circuit-level modelling are formulated. Potential problems related to the generalization of transmission line equations with the use of FO derivatives are presented. It is demonstrated that some of formulations of the FO derivatives have limited...
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Hybrid, Approximate Models of Distributed-Parameter Systems
PublicationThe paper introduces the method of distributed-parameter systems modelling. It enables to obtain low order modal model of the system that experiences Coriolis acceleration component and gyroscopic effect. In such cases, corresponding system equations are non-self-adjoined. To solve this problem modal reduced model is built up for the system without Coriolis acceleration or gyroscopic effect terms. These phenomena are next included...
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Application of muscle model to the musculoskeletal modeling
PublicationThe purpose of this paper is to investigate new fusiform muscle models. Each of these models treats a muscle as a system composedof parts characterized by different mechanical properties. These models explain the influence of differences in the stiffness of lateral parts and the degree of muscle model discretization. Each muscle model is described by a system of differential equations and a single integro-differential equation....
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Numerical solution analysis of fractional point kinetics and heat exchange in nuclear reactor
PublicationThe paper presents the neutron point kinetics and heat exchange models for the nuclear reactor. The models consist of a nonlinear system of fractional ordinary differential and algebraic equations. Two numerical algorithms are used to solve them. The first algorithm is application of discrete Grünwald-Letnikov definition of the fractional derivative in the model. The second involves building an analog scheme in the FOMCON Toolbox...
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Wideband Model Order Reduction for Macromodels in Finite Element Method
PublicationAbstract: This paper presents a novel algorithm for accelerating 3D Finite Element Method simulations by introducing macromodels created in local model order reduction in the selected subdomains of the computational domain. It generates the projection basis for a compact system of equations associated with a separate subdomain. Due to non-linear frequency dependency in the Right Hand Side (RHS), the standard reduction methods do...
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Wideband Macromodels in Finite Element Method
PublicationThis letter proposes a novel projection technique for accelerating Finite Element Method simulations. The algorithm is based on the Second-order Arnoldi Method for Passive Order Reduction (SAPOR). It involves generation of two projection bases and thanks to this it is applicable to the systems of equations, which contain the quadratic frequency-dependence in the input term, that arise when projection is applied locally in the selected...
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Homoclinic and Heteroclinic Orbits for a Class of Singular Planar Newtonian Systems
PublicationThe study of existence and multiplicity of solutions of differential equations possessing a variational nature is a problem of great meaning since most of them derives from mechanics and physics. In particular, this relates to Hamiltonian systems including Newtonian ones. During the past thirty years there has been a great deal of progress in the use of variational methods to find periodic, homoclinic and heteroclinic solutions...
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Uniwersalna metoda projektowania regulacji osi toru z wykorzystaniem pomiarów satelitarnych i optymalizacji
PublicationW pracy zwrócono uwagę na ograniczenia stosowanej w naszym kraju metodyki regulacji osi toru związane w głównym stopniu z uzyskiwaną dokładnością określania istniejącego kształtu toru. Jako rozwiązanie alternatywne wskazano opracowaną przez interdyscyplinarny zespół naukowy Politechniki Gdańskiej i Akademii Marynarki Wojennej / Akademii Morskiej w Gdyni i stosowaną od 2009 roku nowatorską technikę mobilnych pomiarów satelitarnych....
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NUMERYCZNE MODELOWANIE HYDRODYNAMIKI JAKO NARZĘDZIE WSPOMAGANIA PROJEKTOWANIA REKREACYJNYCH I SPORTOWYCH OBIEKTÓW WODNYCH
PublicationW artykule opisano zastosowanie obliczeń numerycznych w procesie projektowania, analizy działania oraz oceny bezpieczeństwa użytkowania wodnych obiektów rekreacyjnych i sportowych. Użytkownicy aquaparków, sportowcy, a szczególnie kibice, oczekują wyjątkowych doznań na obiektach wodnych z jednoczesną gwarancją bezpieczeństwa. Na te kwestie duży wpływ ma hydrodynamika przepływu. Aby właściwie dobrać parametry geometryczne i hydrauliczne...
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Genetic Algorithm Approach for Gains Selection of Induction Machine Extended Speed Observer
PublicationThe subject of this paper is gains selection of an extended induction machine speed observer. A high number of gains makes manual gains selection difficult and due to nonlinear equations of the observer, well-known methods of gains selection for linear systems cannot be applied. A method based on genetic algorithms has been proposed instead. Such an approach requires multiple fitness function calls; therefore, using a quality index...
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Redundantly Actuated 3RRR Parallel Planar Manipulator - Numerical Analyses of its Dynamics Sensitivity on Modifications of its Platform’s Inertia Parameters
PublicationIn the paper, numerical analyses, as well as dynamics of a complex mechanism, are presented. Two objectives are crucial for the paper: inverse dynamic model is needed (dedicated to be use in the model predictive controller); an identification method is searched (some trajectory parameters are controlled, when specific trajectory is tracked under an open-loop model-based control), as selected parameters must be identified for the...
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A quasi-2D small-signal MOSFET model - main results
PublicationDynamic properties of the MOS transistor under small-signal excitation are determined by kinetic parameters of the carriers injected into the channel, i.e., the low-field mobility, velocity saturation, mobility at the quiescent-point (Q-point), longitudinal electric field in the channel, by dynamic properties of the channel, as well as by an electrical coupling between the perturbed carrier concentration in the channel and the...
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SPECTRAL RESPONSE OF STATIONARY JACK-UP PLATFORMS LOADED BY SEA WAVES AND WIND USING PERTURBATION METHOD
PublicationThe paper addresses non-linear vibrations of offshore jack-up drilling platforms loaded by sea waves and wind in their stationary condition using the perturbation method. Non-linearity of dynamic equations of motion for fixed offshore platforms yields from two factors. The first is load excitation generating non-linear velocity coupling in a dynamic system. This coupling is inherent in the modified Morison equation, involving the...
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Source-related Wavefields in Fluids and Dielectrics: A new way of Thinking about Medium Dynamics
PublicationAcoustic and electromagnetic wave phenomena may seem to have a proper formal representation in field theory dating from the 19th century, founded on the mathematics of complex functions. This paper shows, however, that when replacing the classical spectrum-domain approach related to the assumption of harmonic timeform of signals, with a time-domain approach imposingnorestrictionastotheclassoftimeevolutionofsourceandfieldsignals,...
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HYDROACOUSTIC NOISE MEASUREMENTS
PublicationThe paper deals mainly with investigation of underwater noise that propagation is in shallow water. In this paper has been presented the experimental investigation results concerning the distribution of the sound field pressure generated by moving ships in the shallow water at the small distance from the ship. The main acoustical characteristics describing features of the field are spectrograms in pseudo 3D system – distance and frequency...
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Underwater Navigation System Based on Doppler Shifts of a Continuous Wave
PublicationThe paper describes a concept of an underwater navigation system designed to determine the location and speed of its ROVs or divers. Conducted by the Department of Marine Electronic Systems at the Gdansk University of Technology for several years, research has focused on navigation systems which determine positions on the basis of Doppler shifts of echo signals reflected from a moving object. This article presents a different version...
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Study of Noise Propagation for Small Vessels
PublicationThe paper presents the results of the noise propagation analysis in ship structures tested in a number of AHTS (Anchor Handling Tug Supply) vessels. Statistical Energy Analysis (SEA) based on numerical model developed specially for the purpose of this numerical investigation were conducted. This numerical model enabled the analysis of both the structural elements and the acoustic spaces. For the detailed studies 47 points fixed...
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The Rayleigh model of the multipath fading channel
Open Research DataThe dataset contains the results of simulations that are part of the research on modelling the multipath fading in the communication channel. The Rayleigh fading envelope is generated using the Monte-Carlo simulation (MCS) in the LabVIEW programming environment.
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TIME- AND FREQUENCY-DOMAIN QUASI-2D SMALL-SIGNAL MOSFET MODELS
PublicationA novel approach to small-signal MOSFET modeling is presented in this book. As a result, time- and frequency-domain physics-based quasi-2D NQS four-terminal small-signal MOSFET models are proposed. The time-domain model provides the background to a novel DIBL-included quasi‑2D NQS four-terminal frequency-domain small-signal MOSFET model. Parameters and electrical quantities of the frequency-domain model are described by explicit...
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Compressed Projection Bases for Model-Order Reduction of Multiport Microwave Components Using FEM
PublicationThis paper presents a projection basis compression technique for generating compact reduced-order models (ROM) in the FE analysis of microwave devices. In this approach redundancy is removed from the projection basis by means of the proper orthogonal decomposition technique applied to the projected system of linear equations. Compression allows for keeping the size of a reduced-order model as small as possible without compromising...
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Design criterion for hydrodynamic vortex separators
PublicationTechnical objects designing involves determination of geometrical parameters that characterize a given object. When the device is described by the differential equations, an inverse problem brings difficulties, as geometrical values sought condition the solution to the problem. Vortex separators can be designed by the "criterion method'. Firstly, a critical particle is distinguished such that bigger particles are removed from...
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1D Model Callibration on the Basis on 3D calculations for Tesla Turbine
PublicationThe paper presents the system of equations for axisymmetriclaminar flow, after averaging, through the width of interdisk slit ofTesla turbine. Coefficients were introduced, as a result ofaveraging, that improve the efficiency of 1D model. The minimalnumber of such coefficients was determined. The 1D modelmakes it possible to attain analytical solutions to an accuracylimited by these coefficients. Calibration of 1D model depends...
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Modelling of Diffusing Capacity Measurement Results in Lung Microangiopathy Patients. A novel Diagnostic Suppport
PublicationLung microangiopathy is a little known negative influence of diabetes mellitus on the functioning of the lungs. The aim of this study is to design a supportive method for diagnosing lung microangiopathy. This will be based on routinely performed pulmonary measurements as well as on investigation process modelling and data processing. A model of the diffusion of oxygen from the alveoli to the blood has been described with a set...
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Numerical solution of fractional neutron point kinetics in nuclear reactor
PublicationThis paper presents results concerning solutions of the fractional neutron point kinetics model for a nuclear reactor. Proposed model consists of a bilinear system of fractional and ordinary differential equations. Three methods to solve the model are presented and compared. The first one entails application of discrete Grünwald-Letnikov definition of the fractional derivative in the model. Second involves building an analog scheme...