displaying 1000 best results Help
Search results for: DELAY FRACTIONAL EQUATIONS
-
Assessment of Connectivity-based Resilience to Attacks Against Multiple Nodes in SDNs
PublicationIn Software Defined Networks (SDNs), the control plane of a network is decoupled from its data plane. For scalability and robustness, the logically centralized control plane is implemented by physically placing different controllers throughout the network. The determination of the number and placement of controllers is known as the Controller Placement Problem (CPP). In the regular (i.e., failure-free) state, the control plane...
-
The lognormal 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 lognormal fading envelope is generated using the Monte-Carlo simulation (MCS) in the LabVIEW programming environment.
-
Results of the application of tropospheric corrections from different troposphere models for precise GPS rapid static positioning
PublicationIn many surveying applications, determination of accurate heights is of significant interest. The delay caused by the neutral atmosphere is one of the main factors limiting the accuracy of GPS positioning and affecting mainly the height coordinate component rather than horizontal ones. Estimation of the zenith total delay is a commonly used technique for accounting for the tropospheric delay in static positioning. However, in the...
-
International Journal of Qualitative Theory of Differential Equations and Applications
Journals -
Variable Order Differential Models of Bone Remodelling * *This work was supported by FCT, through IDMEC, under LAETA, projects UID/EMS/50022/2013, BoneSys, joint Polish-Portuguese project Modelling and controlling cancer evolution using fractional calculus, PERSEIDS (PTDC/EMS-SIS/0642/2014) and IF/00653/2012
Publication -
Grade of service determination methodology in IP networks with SIP protocol
PublicationAlthough Grade of Service is very important in VoIP providers evaluation, We wasn't able to find any paper regarding the topic of measuring GoS variables for IP networks utilizing SIP, which are defined like for PSTN/ISDN/GSM networks (post-selection delay, answering delay, release delay, or probability of end-to-end blocking). Due to the lack of research in this field, it was necessary to start from defining measures and cover...
-
Miniaturized dual‐band branch‐line coupler with enhanced bandwidth
PublicationIn this letter, a miniaturized hybrid dual-band branch-line coupler (BLC) with enhanced fractional bandwidths is proposed. Compact size and bandwidth enhancement are obtained using meandered transmission line sections with broken symmetry between cross-coupling branches. The circuit is designed at a low numerical cost using surrogate-assisted techniques. The optimized design features small size of only 0.25λg×0.19λg(28% miniaturization...
-
Karolina Lademann Mgr
People -
Entropy Production Associated with Aggregation into Granules in a Subdiffusive Environment
PublicationWe study the entropy production that is associated with the growing or shrinking of a small granule in, for instance, a colloidal suspension or in an aggregating polymer chain. A granule will fluctuate in size when the energy of binding is comparable to k_{B}T, which is the “quantum” of Brownian energy. Especially for polymers, the conformational energy landscape is often rough and has been commonly modeled as being self-similar...
-
Generalized adaptive notch smoothers for real-valued signals and systems
PublicationSystems with quasi-periodically varying coefficients can be tracked using the algorithms known as generalized adaptive notch filters (GANFs). GANF algorithms can be considered an extension, to the system case, of classical adaptive notch filters (ANFs). We show that estimation accuracy of the existing algorithms, as well as their robustness to the choice of design parameters, can be considerably improved by means of compensating...
-
On the fast BSS transition algorithms in the IEEE 802.11r local area wireless networks
PublicationHandover performance is critical to support multimedia services that are becoming increasingly available over the wireless devices. The high transition delay can be unaccepted for such services or can be a source of disruption on the session. On the other side, IEEE 802.11 standard is being extended with new functionalities. Security and QoS features, included in recent IEEE 802.11-2007 standard, add management frames that are...
-
TRAFFIC MODEL OF A MULTIDOMAIN IMS/NGN
PublicationIn this paper we continue our research and present an analytical traffic model of a multidomain Next Generation Network (NGN), which is standardized for delivering multimedia services based on the IP Multimedia Subsystem (IMS). The model takes into account several service scenarios (including registration, intra- and inter-operator calls) and a large set of network parameters. Using the model mean Call Set-up Delay and mean Call...
-
Analysis of IMS/NGN call processing performance using G/G/1 queuing systems approximations
PublicationThe paper concerns the Next Generation Network (NGN), which is standardized for distribution of multimedia services based on the IP Multimedia Subsystem (IMS). To guarantee quality, accurate traffic models of IMS/NGN should be proposed. In the paper we compare results obtained with our analytical and simulation model of a single IMS/NGN domain, where various queuing systems are used in the analytical model (M/G/1 and approximations...
-
Pomiar odpowiedzi impulsowej kanału radiowego na obszarze morskim i przybrzeżnym
PublicationW artykule zaprezentowano wyniki pomiarów odpowiedzi impulsowej kanału radiowego na obszarze morskim i przybrzeżnym. Pomiary przeprowadzono na częstotliwości 1457 MHz a sygnałem sondującym był sygnał o paśmie 10 MHz z modulacją BPSK i pseudoprzypadkową zawartością binarną. Odbierane sygnały były rejestrowane przez dwie stacje ruchome, zainstalowane w samolocie i na łodzi patrolowej. Podczas późniejszej obróbki danych zastosowano...
-
Structural Stability of Nonautonomous Systems
Publication -
Chaos in vibroimpact systems with one degree of freedom in a neighborhood of chatter generation: II
Publication -
A Criterion for Conditional Instability by the First Approximation for Solutions of Differential Systems
Publication -
Chaos in vibroimpact systems with one degree of freedom in a neighborhood of chatter generation: I
Publication -
Hourly GNSS-derived integrated moisture in the global tropics for the years 2001-2018
Open Research DataGlobal tropics are essential in formulating weather patterns and climate across various latitudes through atmospheric teleconnections. Since water vapour is an essential parameter in atmospheric convection and, thus, latent heat release, its tropical variability on different time scales is crucial in understanding weather and climate changes. The provided...
-
The modelling method of discrete-continuous systems
PublicationThe paper introduces a method of discrete-continuous systems modelling. In the proposed method a three-dimensional system is divided into finite elements in only two directions, with the third direction remaining continuous. The thus obtained discrete-continuous model is described by a set of partial differential equations. General difference equations of discrete system are obtained using the rigid finite element method. The limit...
-
Katarzyna Tessmer mgr inż.
PeopleEducation 2012: B.Sc. in Financial Mathematics from the Faculty of Applied Physics and Mathematics, Gdansk University of Technology (2008 – 2012: Bachelor of Science Engineering Studies. Field of study: Mathematics. Specialization: Financial Mathematics.) 2014: M.Sc. in Financial Mathematics from the Faculty of Applied Physics and Mathematics, Gdansk University of Technology (2012 – 2014: Master of Science Engineering Studies....
-
Performance evaluation of IEEE 802.11 fast BSS transition algorithms
PublicationSimultation experiments are conducted to answer the questions if multimedia services can be properly supported in IEEE 802.11r networks. The authors prove that handover delay can be reduced to 22 ms in the average case.
-
Analysis of the process of water entry of an amphibious vehicle
PublicationThe paper presents a method of computational and experimental analysis of the process of water entry of an amphibious vehicle. The computational method is based on the Reynolds Averaged Navier-Stokes Equations (RANSE) solver and the xperiment was carried out in the towing tank at Ship Design and Research Centre S.A. with the use of a scale model. The analysis was focused on the safety of water entry, i.e. the maximum pitch and...
-
Assessing Highway Travel Time Reliability using Probe Vehicle Data
PublicationProbe vehicle data (also known as “floating car data”) can be used to analyze travel time reliability of an existing road corridor in order to determine where, when, and how often traffic congestion occurs at particular road segments. The aim of the study is to find the best reliability performance measures for assessing congestion frequency and severity based on probe data. Pilot surveys conducted on A2 motorway in Poland confirm...
-
A fractionally delaying complex Hilbert transform filter
PublicationPrzedstawiono nowy, dyskretno-czasowy, ułamkowo-opóźniający (FD od ang. fractional delayor), zespolony filtr Hilberta (HTF od ang. Hilbert transform filter) nazwany FDHTF. Filtr ten jest oparty na parze obróconych filtrów o zmiennym opóźnieniu ułamkowym (VFD od ang. variable fractional delayor). Za pomocą filtru FDHTF realizuje się jednocześnie filtrację Hilberta i wprowadzanie ułamkowego opóźnienia do przetwarzanego sygnału. Dzięki...
-
The impact of methods the stochastic analysis on swimming safety of multihull floating units (Part1)
PublicationThe presented article concerns the application of the methods of the stochastic analysis to solve differential equations for multihull catamaran-type floating unit. There was described the continuous process of Markov and the method of equations of Focker-Planck-Kolmogorov. The analysis of dynamics of the multihull unit was carried out with the assumption that the system model is the linear model with six degrees of freedom, on...
-
Long-Term GNSS Tropospheric Parameters for the Tropics (2001-2018) Derived from Selected IGS Stations
PublicationThis paper describes dataset “Tropospheric parameters derived from selected IGS stations in the tropics for the years 2001-2018” contains GNSS-derived zenith tropospheric delay (ZTD), a posteriori corrected zenith wet delay (ZWD), and precipitable water vapour (PWV) time series. These troposphere-related data were estimated for the Jan 2001 – Dec 2018 period for 43 International GNSS Service (IGS) stations located across the global...
-
Performance Models of a Multidomain IMS/NGN Service Stratum
PublicationThis paper quantifies call processing performance (CPP) of a multidomain IMS/NGN architecture, which was proposed to deliver current and future telecommunication services with strict quality requirements, independently of the transport network technologies. A realistic simulation model is used as a reference for evaluation of the analytical results, in which vari-ous types of queuing systems are applied to model the opera-tion...
-
Simulation Model for Application of the SDN Concept in IMS/NGN Network Transport Stratum
PublicationThe paper presents a simulation model allowing examination of cooperation between two currently used telecommunication networks concepts: IP Multimedia Subsystem/Next Generation Network (IMS/NGN) and Software-Defined Networking (SDN). Application of the SDN architecture elements in IMS/NGN networks will enable unified control and management of transport resources for various transport technologies and equipment manufacturers. However,...
-
The impact of methods the stochastic analysis on swimming safety of multihull floating units (Part 2)
PublicationIn part 2 the equations of the catamaran motion were divided into the system of two groups not conjugated with themselves containing the mutually conjugated equations. The feedback is obtained by the linear and nonlinear coefficients of dampening and coefficients of hydrostatic elasticity. The first group includes the symmetric movements (longitudinal movements), and the second group includes the antisymmetric movements (transverse)....
-
A DISCRETE-CONTINUOUS METHOD OF MECHANICAL SYSTEM MODELLING
PublicationThe paper describes a discrete-continuous method of dynamic system modelling. The presented approach is hybrid in its nature, as it combines the advantages of spatial discretization methods with those of continuous system modelling methods. In the proposed method, a three-dimensional system is discretised in two directions only, with the third direction remaining continuous. The thus obtained discrete-continuous model is described...
-
Electrohydrodynamic flow patterns and collection efficiency in narrow wire-cylinder type electrostatic precipitator
PublicationRecently, narrow electrostatic precipitators (ESPs) have become a subject of interest because of their possible application for the cleaning of the exhaust gases emitted by diesel engines. Diesel engines emit fine particles, which are harmful to human and animal health. There are several methods for decrease particulate emission from a diesel engines, but up to now, these methods are not enough effective or very expensive. Therefore,...
-
Effect of Different Structure Type Traffic On Railway Line Capacity
PublicationThe article points to methods of analyzing railway traffic conditions based on two parameters: capacity and delay of trains. The impact of the differentiated railway type structure on the capacity of the railway line was presented. Particular attention has been paid to the assessment of commonly used simplifications in analyzes.
-
Nonlinear Interaction of Modes in a Planar Flow of a Gas with Viscous and Thermal Attenuation
PublicationThe nonlinear interaction of wave and non-wave modes in a gas planar flow are considered. Attention is mainly paid to the case when one sound mode is dominant and excites the counter-propagating sound mode and the entropy mode. The modes are determined by links between perturbations of pressure, density, and fluid velocity. This definition follows from the linear conservation equations in the differential form and thermodynamic...
-
Verification of the Analytical Traffic Model of a Multidomain IMS/NGN Using the Simulation Model
PublicationIn this paper we verify the previously proposed analytical traffic model of a multidomain Next Generation Network (NGN), which is standardized for delivering multimedia services based on the IP Multimedia Subsystem (IMS). For this reason a proper simulation model used, in which not theoretical queuing system models but the operation of real network elements and standardized call scenarios are accurately implemented. Consequently,...
-
Simulation model of IMS/NGN call processing performance
PublicationIn current telecommunications it is assumed that demands of the information society for quickly delivered services will be satisfied by the Next Generation Network (NGN) architecture, which includes IP Multimedia Subsystem (IMS) elements. To guarantee Quality of Service (QoS), proper design and dimensioning of NGN is absolutely necessary, for which appropriate models have to be proposed. As the NGN architecture is very complicated,...
-
Call processing performance in multidomain IMS/NGN architecture
PublicationThe Next Generation Network (NGN) architecture, which bases on the IP Multimedia Subsystem (IMS) concept, is a proposition of a telecommunication network dedicated to the needs of the modern information society. The main goal of NGN is to provide Quality of Service (QoS), for which proper network design and dimensioning are necessary. This also requires appropriate traffic models, which should be efficient and not excessively complicated...
-
Simulation model for assessment of IMS-based NGN call processing performance
PublicationIn current telecommunications it is assumed that demands of information society for quickly delivered services will be satisfied by Next Generation Network (NGN) architecture, which includes IP Multimedia Subsystem (IMS) elements. To guarantee Quality of Service (QoS), proper design and dimensioning of NGN is absolutely necessary, for which appropriate models have to be proposed. As NGN architecture is very complicated, the most...
-
On solvability of initial boundary-value problems of micropolar elastic shells with rigid inclusions
PublicationThe problem of dynamics of a linear micropolar shell with a finite set of rigid inclusions is considered. The equations of motion consist of the system of partial differential equations (PDEs) describing small deformations of an elastic shell and ordinary differential equations (ODEs) describing the motions of inclusions. Few types of the contact of the shell with inclusions are considered. The weak setup of the problem is formulated...
-
A New Approach to Stability Evaluation of Digital Filters
PublicationIn this paper, a new numerical method of evaluating digital filter stability is presented. This approach is based on novel root-finding algorithms at the complex plane using the Delaunay triangulation and Cauchy's Argument Principle. The presented algorithm locates unstable zeros of the characteristic equation with their multiplicities. The proposed method is generic and can be applied to a vast range of systems. Verification of...
-
Dyskretno-ciągła metoda modelowania układów dynamicznych
PublicationW artykule przedstawiono oryginalną metodę modelowania układów dyskretno-ciągłych. Metoda polega na dyskretyzowaniu układu trójwymiarowego jedynie w dwóch wybranych kierunkach. W trzecim z kierunków układ pozostaje ciągły. Otrzymany w ten sposób model jest modelem dyskretno-ciągłym. Opisany jest za pomocą równań różniczkowych cząstkowych. Ogólne równania różnicowe układu dyskretnego otrzymano, wykorzystując metodę sztywnych elementów...
-
Numerical Methods
e-Learning CoursesNumerical Methods: for Electronics and Telecommunications students, Master's level, semester 1 Instructor: Michał Rewieński, Piotr Sypek Course description: This course provides an introduction to computational techniques for the simulation and modeling of a broad range of engineering and physical systems. Concepts and methods discussed are widely illustrated by various applications including modeling of integrated circuits,...
-
Overhead wires detection by FPGA real-time image processing
PublicationThe paper presents design and hardware implementation of real-time image filtering for overhead wires detection divided on image processing and results presentation blocks. The image processing block was separated from the whole implementation, and its delay and hardware complexity was analysed. Also the maximum frequency of image processing of the proposed implementation was estimated.
-
Numerical Analysis of Steady Gradually Varied Flow in Open Channel Networks with Hydraulic Structures
PublicationIn this paper, a method for numerical analysis of steady gradually varied fl ow in channel networks with hydraulic structures is considered. For this purpose, a boundary problem for the system of ordinary differential equations consisting of energy equation and mass conservation equations is formulated. The boundary problem is solved using fi nite difference technique which leads to the system of non-linear algebraic equations....
-
Heteroclinic solutions for a class of the second order Hamiltonian systems
PublicationW pracy dowodzi się istnienia rozwiązań heteroklicznicznych dla pewnej klasy równań różniczkowych zwyczajnych drugiego rzędu typu hamiltonowskiego.
-
The saga of a fish: from a survival guide to closing lemmas
PublicationIn the paper by D. Burago, S. Ivanov and A. Novikov, “A survival guide for feeble fish”, it has been shown that a fish with limited velocity can reach any point in the (possibly unbounded) ocean provided that the fluid velocity field is incompressible, bounded and has vanishing mean drift. This result extends some known global controllability theorems though being substantially nonconstructive. We give a fish a different recipe...
-
The cohomological span of LS-Conley index
PublicationIn this paper we introduce a new homotopy invariant – the cohomological span of LS-Conley index. We prove the theorems on the existence of critical points for a class of strongly indefinite functionals with the gradient of the form Lx+K(x), where L is bounded linear and K is completely continuous. We give examples of Hamiltonian systems for which our methods give better results than the Morse inequalities. We also give a formula...
-
Fixed point indices of iterated smooth maps in arbitrary dimension
PublicationWe give a complete description of possible sequences ofindices of iterations of f at an isolated fixed point, answering inaffirmative the Chow, Mallet-Paret and Yorke conjecture posed in[S.N. Chow, J. Mallet-Parret, J.A. Yorke, A periodic point index whichis a bifurcation invariant, in: Geometric Dynamics, Rio de Janeiro,1981, in: Lecture Notes in Math., vol. 1007, Springer, Berlin, 1983,pp. 109-131].
-
Homotopy invariance of the Conley index and local Morse homology in Hilbert spaces
PublicationIn this paper we introduce a new compactness condition — Property-(C) — for flows in (not necessary locally compact) metric spaces. For such flows a Conley type theory can be developed. For example (regular) index pairs always exist for Property-(C) flows and a Conley index can be defined. An important class of flows satisfying the this compactness condition are LS-flows. We apply E-cohomology to index pairs of LS-flows and obtain...
-
Integrate-and-fire models with an almost periodic input function
PublicationWe investigate leaky integrate-and-fire models (LIF models for short) driven by Stepanov and μ-almost periodic functions. Special attention is paid to the properties of the firing map and its displacement, which give information about the spiking behavior of the considered system. We provide conditions under which such maps are well-defined and are uniformly continuous. We show that the LIF models with Stepanov almost periodic...