Search
Filters
total: 1335
filtered: 1178
displaying 1000 best results Help
Search results for: STOCHASTIC WAVE REALIZATION
-
Discrete-time estimation of nonlinear continuous-time stochastic systems
PublicationIn this paper we consider the problem of state estimation of a dynamic system whose evolution is described by a nonlinear continuous-time stochastic model. We also assume that the system is observed by a sensor in discrete-time moments. To perform state estimation using uncertain discrete-time data, the system model needs to be discretized. We compare two methods of discretization. The first method uses the classical forward Euler...
-
Discrete-time estimation of nonlinear continuous-time stochastic systems
PublicationIn this paper we consider the problem of state estimation of a dynamic system whose evolution is described by a nonlinear continuous-time stochastic model. We also assume that the system is observed by a sensor in discrete-time moments. To perform state estimation using uncertain discrete-time data, the system model needs to be discretized. We compare two methods of discretization. The first method uses the classical forward Euler...
-
Application of a stochastic compartmental model to approach the spread of environmental events with climatic bias
PublicationWildfires have significant impacts on both environment and economy, so understanding their behaviour is crucial for the planning and allocation of firefighting resources. Since forest fire management is of great concern, there has been an increasing demand for computationally efficient and accurate prediction models. In order to address this challenge, this work proposes applying a parameterised stochastic model to study the propagation...
-
Design, Realization and Measurements of Enhanced Performance 2.4 GHz ESPAR Antenna for Localization in Wireless Sensor Networks
PublicationThis paper presents the design, realization and measurements of an Electronically Steerable Parasitic Array Radiator (ESPAR) antenna with enhanced performance of estimating the incoming signal direction. Designed antenna is dedicated for 2.4 GHz ISM applications with emphasis on Wireless Sensor Networks (WSN). Proposed antenna provides different radiation patterns by proper configuration of the parasitic elements. Thus, several...
-
Asynchronous distributed state estimation for continuous-time stochastic processes
PublicationWe consider the problem of state estimation of a continuous-time stochastic process using an asynchronous distributed multi-sensor estimation system (ADES). In an ADES the state of a process of interest is estimated by a group of local estimators. Each local estimator based, for example, on a Kalman filter, performs single sensor filtration but also fusion of its local results and results from other (remote) processors to compute...
-
Variations of Ship’s Deck Elevation Due to Stochastic Process of Containers Loading
PublicationThe stochastic process of container loading is described in the paper with special emphasis to ship motion when she is lying at a quay. The 3 DOF system was applied to describe rolling, pitching and heaving of a vessel which may cause a significant variations of momentary deck elevation. The realistic range of such variations are assessed for a variety of cargo locations on-board and a phase shift between two independent gantries...
-
Locally Adaptive Cooperative Kalman Smoothing and Its Application to Identification of Nonstationary Stochastic Systems
PublicationOne of the central problems of the stochastic approximation theory is the proper adjustment of the smoothing algorithm to the unknown, and possibly time-varying, rate and mode of variation of the estimated signals/parameters. In this paper we propose a novel locally adaptive parallel estimation scheme which can be used to solve the problem of fixed-interval Kalman smoothing in the presence of model uncertainty. The proposed solution...
-
Comparative analysis of numerical with optical soliton solutions of stochastic Gross–Pitaevskii equation in dispersive media
PublicationThis article deals with the stochastic Gross–Pitaevskii equation (SGPE) perturbed with multiplicative time noise. The numerical solutions of the governing model are carried out with the proposed stochastic non-standard finite difference (SNSFD) scheme. The stability of the scheme is proved by using the Von-Neumann criteria and the consistency is shown in the mean square sense. To seek exact solutions, we applied the Sardar subequation...
-
FPGA realization of the high-speed binary-to-residue converter
Publicationprzedstawiono architekturę i realizację w technologii fpga konwertera z systemu binarnego do systemu resztowego. algorytm konwertera oparty jest na podziale słowa wejściowego na segmenty 4-bitowe i następnie obliczeniu reszty liczby reprezentowanej przez dany segment, sumowaniu binarnym przy zastosowaniu csa i redukcji modulo w układzie dwuoperandowego sumatora modulo.
-
ADAPTATION PROCESSES OF THE AGRARIAN SECTOR FOR REALIZATION OF THE EXISITING POTENTIAL
Publication -
Realization of multi-operand modular adders in the FPGA technology
PublicationW pracy opisano projektowanie i realizację struktur wielooperandowych sumatorów modularnych (MOMA) w środowisku Xilinx FPGA z użyciem technologii Virtex-6. Projekt oparty jest na pamięciach LUT (26x1), które symulują małe pamięci RAM służące jako podstawowy komponent do realizacji sumatorów. W pracy pokazano MOMA dla dodawania modularnego operandów 5-bitowych. Najpierw rozważono ogólne struktury MOMA i następnie dwa podstawowe...
-
Design and realization of two-operand modular adders in the FPGA
PublicationW pracy zaprezentowano strukturę sumatorów modularnych w środowisku Xilinx z użyciem rodziny układów Virtex-6. Rozważono dwa typy sumatorów, jeden dla modułów 5-bitowych i drugi dla 6-bitowych. Zaprojektowano ich struktury i podano eksperymentalne wyniki implementacji.
-
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...
-
On the decomposition of stochastic cellular automata
Publication -
Mathematical model to assess energy consumption using water inflow-drainage system of iron-ore mines in terms of a stochastic process
PublicationPurpose is to develop a unified mathematical model to assess energy efficiency of a water inflow-drainage process as the real variant of stochastic method for water pumping from underground workings of iron-ore mines. Methods. The research process was based upon the methods of probability theory as well as stochastic modelling methods. The stochastic function integration has been reduced to summation of its ordinates and further...
-
Wave propagation in damage assessment of ground anchors
PublicationThe inspection possibilities of ground anchors are limited to destructive test such as pull-out test. Guided wave propagation gives an opportunity to develop an inspection system dedicated to determine the condition of inspected element without violation of their integrity. In this paper the experimental study on wave propagation in laboratory models of ground anchors are presented. Experiments were conducted for different bonding...
-
Reservoir Influence on Pressure Wave Propagation in Steel Pipes
PublicationThe relation between the length of steel pipe and the pressure wave period in the system, reservoir-pipe-valve, is discussed. Experiments carried out for the short steel pipes showed that in such a system, the pressure wave celerity estimated using the measured wave cycles systematically increases with the increase of the pipe length. The observed differences can exceed even 90 m=s. As the pressure wave traveling in the pipe with...
-
Four-state stochastic model of changes in the reliability states of a motor vehicle
PublicationThe properties of semi-Markov processes have been generally characterized and the applicability of the theory of such processes to the determining of the reliability of motor cars and other road vehicles has been explained. A formal description of the process of changes in the motor vehicle technical states considered as reliability states and a model of this process in the form of a one-dimensional stochastic process have been...
-
The description of non-linear interactions of wave and non-wave modes in a non-adiabatic plasma flow
PublicationThe method of derivation of non-linear equations for interacting modes is explained and applied to a plasma's flow affected by a magnetic field. It is based on the linear projecting of the total perturbation field into specific variations of variables in individual modes of a flow. The method may be applied in many examples of fluid flows with different mechanisms of non-adiabaticity. It is of special importance in complex flows...
-
Analysis of wave propagation in a bolted steel joint
PublicationThe paper presents results of numerical and experimental investigations of elastic wave propagation in a bolted single-lap joint. The research was carried out for both symmetric and antisymmetric Lamb wave modes. In experimental studies the PZT transducers were used to excite and register wave propagation signals. The controlled value of the torque during measurements was ensured by the use of high precision torque wrenches. Numerical...
-
Acoustics of concert hall at academy of music in Gdańsk, project and realization
PublicationArtykuł opisuje właściwości akustyczne sali koncertowej Akademii Muzycznej w Gdańsku, ukończonej w roku 2007. Przedstawiono zalecenia akustyczne do projektu architektonicznego w zakresie akustyki budowlanej i akustyki wnętrz. Podano wyniki pomiarów akustycznych na kolejnych etapach realizacji obiektu.
-
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...
-
Deterministic versus stochastic modelling of unsaturated flow in a sandy field soil based on dual tracer breakthrough data
PublicationThe 216 km2 Neuenhagen Millcreeck catchment can be characterized as a drought sensitive landscape in NE Germany. It is therefore a fundamental human interest to understand how water that fell as precipitation moves through the unsaturated soils and recharges groundwater. Additionally, a better knowledge of nutrient transport from soil to groundwater is important also, especially in landscapes with light sandy soils. For a better...
-
PLC-based Implementation of Stochastic Optimization Method in the Form of Evolutionary Strategies for PID, LQR, and MPC Control
PublicationProgrammable logic controllers (PLCs) are usually equipped with only basic direct control algorithms like proportional-integral-derivative (PID). Modules included in engineering software running on a personal computer (PC) are usually used to tune controllers. In this article, an alternative approach is considered, i.e. the development of a stochastic optimizer based on the (μ,λ) evolution strategy (ES) in a PLC. For this purpose,...
-
Stochastic approach to movements of a multihull on waves
PublicationW artykule przedstawiono metodę wyznaczania różniczkowych równań ruchu.Układ równań różniczkowych został przedstwaiony dla ruchów antysymetrycznych jednoski wielokadłubowej (poprzeczne ruchy liniowe, poprzeczne ruchy kątowe, poziome ruchy kątowe). Dla tych ruchów zbudowano stochastyczne równania różniczkowe.
-
Multihull vessel excitations in stochastic formulation
PublicationPraca dotyczy określania wymuszeń wielokadłubowej jednostki pływającej w ujęciu stochastycznym. Wymuszenia ruchu jednostek pływających pochodzą od ruchu fal morskich i działania wiatru. Najczęściej jest to falowanie nieregularne i dlatego w badaniach dynamiki takich jednostek zakłada się, że proces falowania ma charakter probabilistyczny. Przeprowadzono analizę dynamiki jednostki wielokadłubowej na liniowym modelu, na który działa...
-
Tribology of stochastic phenomena on the hard tissue.
PublicationPraca przedstawia model matematyczny zjawisk tribologicznych podczas hodowli tkanek twardych, w tym chrząstek stawowych. Uwzględnia się chropowatości powierzchni hodowanych chrząstek. Problem tribologiczny uzewnętrzniony został koniecznością sterowania wartościami sił tarcia jakie powstają w cienkiej warstewce przyściennej opływanej tkanki cieczą biologiczną w trakcie hodowli. Taki model matematyczny nie był do tej pory rozpatrywany.
-
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 Finite Element Approach for Wave Propagation in Elastic Solids
PublicationThis book focuses on wave propagation phenomena in elastic solids modelled by the use of the finite element method. Although the latter is a well-established and popular numerical tool used by engineers and researchers all around the word the process of modelling of wave propagation can still be a challenge. The book introduces a reader to the problem by presenting a historical background and offering a broad perspective on the...
-
Measuring research on radio wave propagation
PublicationTelecommunication connections are increasingly based on the wireless links, both fixed and mobile, carried out under different radio systems. This kind of solution has many advantages. However, the propagation medium is a factor that causes many difficulties in designing wireless networks, because of large diversity of propagation environments. Transmission loss in each environment is determined by many variables phenomena and...
-
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...
-
Application of Pierson-Moskowitz wave spectrum to solution differential equations of multihull vessel
PublicationMotion of a dynamic system can be generated by different external or internal factors. At mathematical modelling external excitation factors of the most significant effect on the system, are selected. Such external factors are usually called excitations. Response of the system to given excitations is mathematically characterized by a definite transformation called operator of a system. For a broad class of dynamic systems the...
-
Investigation of continuous wave jamming in an IEEE 802.15.4 network
PublicationThis paper presents how continuous wave jamming affects IEEE 802.15.4 network. To this end, an office-based measurement setup has been proposed. Within the measurement area, 25 nodes have been set up in order to create a IEEE 802.15.4 tree-based test network structure. A dedicated jamming device that generates and transmits a continuous wave signal has been developed. Several tests have been conducted and presented to demonstrate...
-
Investigations of the Methods of Time Delay Measurement of Stochastic Signals Using Cross-correlation with the Hilbert Transform
PublicationThe article presents the results of simulation studies of four methods of estimating time delay for random signals using cross-correlation with the Hilbert Transform. Selected models of mutually delayed stochastic signals were used in the simulations, corresponding to the signals obtained from scintillation detectors in radioisotope measurements of liquid-gas two-phase flow. Standard deviations of the values of the individual functions...
-
New Approach to Noncasual Identification of Nonstationary Stochastic FIR Systems Subject to Both Smooth and Abrupt Parameter Changes
PublicationIn this technical note, we consider the problem of finite-interval parameter smoothing for a class of nonstationary linear stochastic systems subject to both smooth and abrupt parameter changes. The proposed parallel estimation scheme combines the estimates yielded by several exponentially weighted basis function algorithms. The resulting smoother automatically adjusts its smoothing bandwidth to the type and rate of nonstationarity...
-
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...
-
An Efficient PEEC-Based Method for Full-Wave Analysis of Microstrip Structures
PublicationThis article introduces an efficient method for the equivalent circuit characterization and full-wave analysis of microstrip structures, leveraging the full-wave partial element equivalent circuit (PEEC). In particular, the multilayered Green's function is evaluated using the discrete complex-image method (DCIM) and employed to establish the mixed potential integral equations. The proposed strategy considers time delays for the...
-
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”...
-
Numerical Study of Concrete Mesostructure Effect on Lamb Wave Propagation
PublicationThe article presents the results of the numerical investigation of Lamb wave propagation in concrete plates while taking into account the complex concrete mesostructure. Several concrete models with randomly distributed aggregates were generated with the use of the Monte Carlo method. The influence of aggregate ratio and particle size on dispersion curves representing Lamb wave modes was analyzed. The results obtained for heterogeneous...
-
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...
-
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...
-
Stochastic approach to the dynamics of a linear floating object
PublicationArtykuł stanowi prezentację metody różniczkowych równań stochastycznych w zastosowaniu do analizy dynamiki obiektów pływających. Analizowany jest ruch jednostki pływającej jako obiektu liniowego z uwzględnieniem w równaniach stochastycznych nieliniowości, występującej w wymuszeniach zewnętrznych działających na obiekt. Stochastyczne równania różniczkowe są zapisane dla sprzężonych ruchów symetrycznych.
-
Stochastic approach to the dynamics of marine floating object
PublicationAnalizowany jest ruch jednostki pływającej z uwzględnieniem w równaniach stochastycznych nieliniowości, występującej w wymuszeniach zewnętrznych działających na obiekt. Stochastyczne równania różniczkowe są zapisane dla sprzężonych ruchów symetrycznych.
-
Stochastic model of the process of diesel engine operation.
PublicationStreszczenie: Najistotniejszym problemem eksploatacji silników o zapłonie samoczynnym jest problem racjonalnego (a zwłaszcza optymalnego) sterowania procesem eksploatacji tych silników. Sterowanie takie może ułatwić zastosowanie iteracyjnego algorytmu wyznaczania optymalnych strategii opracowanego przez R.A. Howarda. Wykorzystanie jednak tego algorytmu do sterowania procesem eksploatacji silników wymaga między innymi opracowania...
-
Approximation of Covariance Function with Application to Stochastic Mechanics.
PublicationW pracy przedstawiono koncepcję rozwinięć kanonicznych dla funkcji losowych oraz możliwość ich zastosowania w stochastycznej mechanice gruntów. Rozpatrzono rozkład widmowy, rozwinięcia Karhunena-Loevego oraz rozwinięcia ortogonalne zmodyfikowanymi wielomianami Hermite'a. Przeprowadzono analizę błędów dla zagadnienia warstwy gruntu o losowych parametrach sprężystych, uzyskano analityczne rozwiązanie systemu stochastycznego.
-
Limit Analysis of a Strip Footing on Stochastic Subsoil.
PublicationW pracy analizowana jest ława fundamentowa posadowiona na losowym podłożu.Poszukiwane są oszacowania nośności podłoża na podstawie twierdzeń o dolnej i górnej ocenie obciążenia granicznego. Dla różnych statycznie dopuszczalnych pól naprężenia i kinematycznie dopuszczalnych pól prędkości, wyznaczono wartości oczekiwane i wariancje obciążenia granicznego. Pozwoliło to na określenie odpowiednich dystrybuant, rozumianych...
-
Damage localisation in a stiffened plate structure using a propagating wave
PublicationThe paper presents an application of changes in propagating waves for damage detection in a stiffened aluminium plate. The experimental investigation was conducted on an aluminium plate with riveted two L-shape stiffeners. The wave has been excited with a piezoelectric transducer and measured with the Laser Scanning Doppler Vibrometer. Recorded signals were analysed using the special signal processing techniques developed for damage...
-
FPGA realization of high-speed multi-stage FIR filter in residue arithmetic
PublicationW pracy przedstawiono implementację szybkiego wielostopniowego, kaskadowego filtru FIR w technologii FPGA. Zastosowanie arytmetyki resztowej pozwala na uzyskanie dużych częstotliwości próbkowania w zwiżaku z użyciem małych mnożników. Zalety wynikające z uzycia arytmetyki resztowej sa w pewnym stopniu ograniczne koniecznością wykonania skalowania przy kaskadowym połaczeniu filtrów FIR, tak aby uniknąć nadmiaru arytmetycznego. W...