Search
Filters
total: 3344
displaying 1000 best results Help
Search results for: PROPAGATION MODELS ADJUSTMENT
-
Statistical adjustment of selected propagation models for applications in container terminal
Publication -
Empirical Adjustment of the Selected Propagation Models for Application in the Peculiar Environment of the Container Terminal
PublicationIt is important to look for any propagation model that could be useful for designing mobile radio systems in container terminal environment. Selected propagation models have been investigated. The applied research methodology has been described too. Results of the statistical adjustment in terms of signal loss determination in such environment have been analysed. The analysis has proved effectiveness of adjustment by increasing...
-
Selected Propagation Models Modification for Application in Container Terminal
PublicationIt is particularly important to look for any propagation model that could be useful for designing mobile radio systems in container terminal environment. The selected propagation models have been investigated. The applied research methodology has been described too. Results of the statistical adjustment in terms of signal loss determination in such environment have been analysed. The analysis have proved effectiveness of adjustment...
-
Signal propagation in electromagnetic media described by fractional-order models
PublicationIn this paper, signal propagation is analysed in electromagnetic media described by fractional-order (FO) models (FOMs). Maxwell’s equations with FO constitutive relations are introduced in the time domain. Then, their phasor representation is derived for one-dimensional case of the plane wave propagation. With the use of the Fourier transformation, the algorithm for simulation of the non-monochromatic wave propagation is introduced....
-
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...
-
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...
-
On the usefulness of selected radio waves propagation models for designing mobile wireless systems in container terminal environment
Publication -
Improved-Efficacy EM-Driven Optimization of Antenna Structures Using Adaptive Design Specifications and Variable-Resolution Models
PublicationOptimization-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...
-
Rozprzestrzenianie się w podtorzu skutków katastrof kolejowych z udziałem materiałów niebezpiecznych
PublicationDuża część przewozów materiałów niebezpiecznych prowadzona jest koleją. W związku z tym bezpieczeństwo tych przewozów nabiera coraz większego znaczenia. Każda katastrofa z udziałem materiałów niebezpiecznych ma negatywny wpływ na uczestników tego zdarzenia oraz na otaczające środowisko, bowiem jej zasięg na ogół nie jest lokalny. Z tego wynika, że w przypadku zaistnienia katastrofy należy minimalizować jej skutki oraz w dalszych...
-
Finite element models used in diagnostics of transverse cracks in bridge approach pavement
Open Research DataTransverse cracks in the asphalt pavement were observed on bridge structures next to single-module expansion joints with a 5 meter approach slab set at the depth of 1 m. The finite element (FE) models of the approach pavement were created to investigate the reasons of premature cracking and crack initiation mechanism over the back edge of the abutment...
-
Paweł Szymon Dąbrowski dr inż.
PeopleDr. Eng. Paweł Szymon Dąbrowski studied geodesy and cartography at the University of Warmia and Mazury in Olsztyn from 2004-2009, where he obtained the title of Master of Science in Engineering. In the years 2009-2016, he worked as a land surveyor in Iława and Gdańsk. He gained professional experience during the construction of the Pomeranian Metropolitan Railway, which helped him obtain a national surveying license in 2015. In...
-
Badania i analiza uwarunkowań propagacyjnych w środowisku uprzemysłowionym
PublicationGłówne osiągnięcia rozprawy: - wykonanie – zgodnie z wymaganiami normatywnymi zawartymi w zaleceniach ITU-R – nowatorskich badań tłumienia sygnału radiowego na terenie Głębokowodnego Terminalu Kontenerowego (ang. Deepwater Container Terminal - DCT) w Gdańsku i zebranie obszernego materiału pomiarowego, liczącego blisko 290 tysięcy przypadków propagacyjnych, - przeprowadzenie statystycznych badań przydatności wybranych znanych modeli...
-
Reduced-cost electromagnetic-driven optimisation of antenna structures by means of trust-region gradient-search with sparse Jacobian updates
PublicationNumerical optimisation plays more and more important role in the antenna design. Because of lack of design-ready theoretical models, electromagnetic (EM)-simulation-driven adjustment of geometry parameters is a necessary step of the design process. At the same time, traditional parameter sweeping cannot handle complex topologies and large number of design variables. On the other hand, high computational cost of the conventional...
-
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
Journals -
Accelerated Gradient-Based Optimization of Antenna Structures Using Multi-Fidelity Simulations and Convergence-Based Model Management Scheme
PublicationThe importance of numerical optimization has been steadily growing in the design of contemporary antenna structures. The primary reason is the increasing complexity of antenna topologies, [ a typically large number of adjustable parameters that have to be simultaneously tuned. Design closure is no longer possible using traditional methods, including theoretical models or supervised parameter sweeping. To ensure reliability, optimization...
-
IEEE Antennas and Wireless Propagation Letters
Journals -
Tolerance Optimization of Antenna Structures by Means of Response Feature Surrogates
PublicationFabrication tolerances and other types of uncertainties, e.g., the lack of precise knowledge of material parameters, have detrimental effects on electrical and field performance of antenna systems. In the case of input characteristics these are particularly noticeable for narrow- and multi-band antennas where deviations of geometry parameters from their nominal values lead to frequency shifts of the operating frequency bands. Improving...
-
Cost-efficient design optimization of compact patch antennas with improved bandwidth
PublicationIn this letter, a surrogate-assisted optimization procedure for fast design of compact patch antennas with enhanced bandwidth is presented. The procedure aims at addressing a fundamental challenge of the design of antenna structures with complex topologies, which is simultaneous adjustment of numerous geometry parameters. The latter is necessary in order to find a truly optimum design and cannot be executed-at the level of high-fidelity...
-
Computationally Efficient Surrogate-Assisted Design of Pyramidal-Shaped 3D Reflectarray Antennas
PublicationReflectarrays (RAs) have been attracting considerable interest in the recent years due to their appealing features, in particular, a possibility of realizing pencil-beam radiation patterns, as in the phased arrays, but without the necessity of incorporating the feeding networks. These characteristics make them attractive solutions, among others, for satellite communications or mobile radar antennas. Notwithstanding, available microstrip...
-
Wpływ parametrów strugi paliwa wtryskiwanego do cylindra silnika okrętowego na początkową fazę rozpylania
PublicationPrzedmiotem rozprawy jest analiza procesu wtrysku oleju napędowego do cylindra silnika okrętowego z zapłonem samoczynnym i bezpośrednim wtryskiem paliwa. Analiza tego zagadnienia została przeprowadzona w aspekcie wpływu makro parametrów strugi na początkową fazę rozpylania oleju napędowego. Celem niniejszej pracy jest określenie wpływu współczynnika L/D (długość otworu/średnica) otworu wylotowego wtryskiwacza na zmianę charakterystyki...
-
Sławomir Jerzy Ambroziak dr hab. inż.
PeopleSławomir J. Ambroziak was born in Poland, in 1982. He received the M.Sc., Ph.D. and D.Sc. degrees in radio communication from Gdańsk University of Technology (Gdańsk Tech), Poland, in 2008, 2013, and 2020 respectively. Since 2008 he is with the Department of Radiocommunication Systems and Networks of the Gdańsk Tech: 2008-2013 as Research Assistant, 2013-2020 as Assistant Professor, and since 2020 as Associate Professor. He is...
-
IET Microwaves Antennas & Propagation
Journals -
Tropospheric delays derived from GNSS observations during the derecho event in Poland of 11th August 2017
Open Research DataPropagation of global navigation satellite systems (GNSS) radio signals is disturbed by the current state of the Earth's atmosphere. For this reason, advances processing of GNSS signals can be used for investigation of the atmospheric condition. In case of troposphere, the GNSS signals allow for obtain information of tropospheric delay, which is mainly...
-
Generalized Formulation of Response Features for Reliable Optimization of Antenna Input Characteristics
PublicationElectromagnetic (EM)-driven parameter adjustment has become imperative in the design of modern antennas. It is necessary because the initial designs rendered through topology evolution, parameter sweeping, or theoretical models, are often of poor quality and need to be improved to satisfy stringent performance requirements. Given multiple objectives, constraints, and a typically large number of geometry parameters, the design closure...
-
Analog modelling in qualitative analysis of vibration propagation
PublicationThe theory of dynamic systems is usually used to model the real systems. The models are based on solving ordinary differential equations, partial or difference, which enable obtaining the relation between input signal and the system response (output signal). The analogy between those models and generalized dynamic systems or control systems can be practically used. Vibration propagation can be described in a similar way as 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...
-
Models in Spatial Development
e-Learning Courses -
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...
-
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...
-
New Method for Determination of Adjustment Corrections for Crane Rail Axes
PublicationElectronic tacheometers are currently a standard instrument used in geodetic work, including also geodetic engineering measurements. One of the many applications of tacheometers in engineering geodesy are 3D control measurements of crane rail axes. This paper proposes a new method of computing adjustment corrections for crane rail axes based on 3D polar measurements performed with an electronic tacheometer. The intermediary method...
-
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...
-
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...
-
Assessment of Adjustment of GNSS Railway Measurements with Parameter-Binding Conditions in a Stationary Scenario
PublicationThe study aims to assess the applicability of the ordinary least squares method, robust estimation, and conditions-binded adjustment in processing the six synchronous coordinate pairs of global navigation satellite system (GNSS) receivers. The research is part of the research project InnoSatTrack, focused on the enhancement of the determination of geometrical parameters of railway tracks using GNSS, inertial, and other sensors....
-
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...
-
Generation and Propagation of Nonlinear Waves in a Towing Tank
PublicationThe paper presents the results of the research focused on linear and nonlinear wave generation and propagation in a deepwater towing tank equipped with a single flap-type wavemaker of variable draft. The problem of wave generation and propagation has been theoretically formulated and solved by applying an analytical method; linear and nonlinear solutions were obtained. The linear solution has been verified experimentally. The...
-
Efficient Complex Root Tracing Algorithm for Propagation and Radiation Problems
PublicationAn efficient complex root tracing algorithm for propagation and radiation problems is presented. The proposed approach is based on a discretization of Cauchy’s Argument Principle and its generalization to the C × R space. Moreover, an engagement of the tracing process with a global root finding algorithm recently presented in the literature is performed. In order to confirm a validity and efficiency of the proposed technique, a...
-
Marek Czachor prof. dr hab.
People -
An Empirical Propagation Model for Corridors in Office Buildings
PublicationThis paper presents an empirical propagation path loss model for corridors in office buildings. The proposed model estimates changeable character of radio signal attenuation, based on a special approach as a combination of the simple free-space model with the author’s model. The measurement stand and measurement scenario are described. The propagation path loss research have been made in corridor for different frequencies in range...
-
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...
-
Propagation of Acoustic Disturbances in Shallow Sea
PublicationPropagation of acoustic waves in shallow sea differs fundamentally from the same phenomenon occurring in deep sea in view of non-negligible distance from the sea bottom in the first case, where presence of two regions limiting the water layer results in the acoustic pressure distribution induced by a harmonic source has an interferential nature as a result of multi-path propagation of the acoustic signal. These interferential properties...
-
GRAPHICAL MODELS
Journals -
STOCHASTIC MODELS
Journals -
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...
-
Characteristics of Propagation Conditions in the Container Terminal Environment
PublicationIn the paper a characteristics of propagation conditions in the container terminal environment is presented. The investigated environment is characterized on the example of Gdansk Deepwater Container Terminal in Poland. An empirical propagation model for path loss calculation in mobile radio links in a container terminal environment is presented.
-
Models in spatial development 2024/25
e-Learning Courses -
Empirical Propagation Model for the Container Terminal Environment
PublicationIn the paper the empirical propagation model for mobile radio links in a container terminal environment is presented and the investigated environment Deepwater Container Terminal in Gdansk, Poland) is characterized. Described empirical model was elaborated on the basis of almost 290 thousand propagation path measurements in real conditions. The diversity of conditions occurring in different places of the container terminal has...
-
COMPARISON OF INFINITE ELEMENT MODELS
PublicationThe main objective of this paper is to show the comparison of two models of infinite ab- sorbing layer with increasing damping in numerical investigations of elastic wave prop- agation in unbounded structures. This has been achieved by the Authors by a careful in- vestigation of two different engineering structures characterised by gradually increasing geometrical and mathematical description complexities. The analysis included...
-
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...
-
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...