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Differential analysis of dynamic immittance spectra
PublikacjaThis work presents a new approach to the analysis of immittance spectrograms of systems characterised by non-stationarity. The possibility of linking the evolution of the immittance response with changes in the parameters describing the system is achieved by introducing a spectrum in differential form. By using the above procedure, it becomes possible to separate elements with a dependence (or lack thereof) from an independent...
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A simple and efficient hybrid discretization approach to alleviate membrane locking in isogeometric thin shells
PublikacjaThis work presents a new hybrid discretization approach to alleviate membrane locking in isogeometric finite element formulations for Kirchhoff–Love shells. The approach is simple, and requires no additional dofs and no static condensation. It does not increase the bandwidth of the tangent matrix and is effective for both linear and nonlinear problems. It combines isogeometric surface discretizations with classical Lagrange-based...
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Highly linear CMOS triode transconductor for VHF applications
PublikacjaA high-speed, fully balanced complementary-symmetry metal-oxide-semiconductor (CMOS) triode transconductor is presented. The proposed approach exploits a pseudo-differential-pair triode configuration with a simple adaptive circuit stabilising the drain-to-source voltages of metal-oxide-semiconductor (MOS) transistors. Since no additional active circuits (apart from the resistors made of the cut-off MOS devices) and no feedback...
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Compact 4 × 4 butler matrix with non‐standard phase differences for IoT applications
PublikacjaButler matrices represent a popular class of feeding networks for antenna arrays. Large dimensions and the lack of flexibility in terms of achievable output phase difference make conventional Butler structures of limited use for modern communication devices. In this work, a compact planar 4 × 4 matrix with non-standard relative phase shifts of –30º, 150º, –120º, and 60º has been proposed. The structure is designed to operate at...
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Rapid EM-driven antenna dimension scaling through inverse modeling
PublikacjaIn this letter, a computationally feasible technique for dimension scaling of antenna structures is introduced. The proposed methodology is based on inverse surrogate modeling where the geometry parameters of the antenna structure of interest are explicitly related to the operating frequency. The surrogate model is identified based on a few antenna designs optimized for selected reference frequencies. For the sake of computational...
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A Wideband Corrugated Ridged Horn Antenna with Enhanced Gain and Stable Phase Center for X- and Ku-Band Applications
PublikacjaIn this letter, a structure and design procedure of a novel double-flared conical horn antenna with an improved gain and a stable phase center is presented. The antenna incorporates a hybrid ridged and corrugated structure. A double-ridged section is responsible for ensuring a wideband operation, whereas the corrugated section supports the hybrid mode. The antenna impedance bandwidth (VSWR < 2) is 6 GHz to 20 GHz. Excellent performance...
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A Solution to Image Processing with Parallel MPI I/O and Distributed NVRAM Cache
PublikacjaThe paper presents a new approach to parallel image processing using byte addressable, non-volatile memory (NVRAM). We show that our custom built MPI I/O implementation of selected functions that use a distributed cache that incorporates NVRAMs located in cluster nodes can be used for efficient processing of large images. We demonstrate performance benefits of such a solution compared to a traditional implementation without NVRAM...
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Measurement of Impulse Response of Shallow Water Communication Channel by Correlation Method
PublikacjaPerformances of underwater acoustic communication (UAC) systems are strongly related to specific propagation conditions of the underwater channel; conditions that can additionally change in time due to the movement of the acoustic system transmitter and receiver or to reflection by underwater objects of the transmitted signal. The time-varying impulse response is a comprehensive description of dynamically changing transmission...
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Reliable low-cost surrogate modeling and design optimisation of antennas using implicit space mapping with substrate segmentation
PublikacjaAbstract: In this work, a reliable methodology for fast simulation-driven design optimisation of antenna structures is proposed. The authors’ approach exploits implicit space mapping (ISM) technology. To adopt it for handling antenna structures, they introduce substrate segmentation with separate dielectric permittivity value assigned for each segment as ISM preassigned parameters. At the same time, the coarse model for space mapping...
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Detection system for optical coherence tomography: Czerny-Turner spectrometer
PublikacjaResearch methods based on spectral analysis have powerful impact on development in many field of science. Signal spectrum can be a source of useful and important data. It enables to obtain information about physical and chemical properties of tested materials. This paper has been devoted to describe optical design for high resolution spectrometer, which is significant element of optical coherence tomography (OCT) systems. Designed...
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Analytical modeling of electric drives for vehicle traction control systems
PublikacjaWheel-torque control bandwidth in vehicle dynamics model is crucial in evaluating optimal tracking ability of tire slip and in analysis of control system stability. Electric drives’ control dynamics are influenced by timing of digital control events, e.g. by sampling instant of motor currents. Reflecting this timing in drive analytical models is therefore important for analysis of vehicle traction systems. The paper considers five...
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Investigation of noises in the EPN weekly time series
PublikacjaThe constantly growing needs of permanent stati ons’ velocities users cause their stability level to increase. To this research we included more than 150 stations located across Europe operating within the EUREF Permanent Network (EPN) w ith weekly changes in the ITRF2005 reference frame. The obvious long-range dependencies in the stochastic part of GPS time series were p roven by Ljung-Box...
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High-accuracy polarimetric studies on lead germanate single crystals
PublikacjaA high-accuracy polarimetric technique has been used for the characterization of a lead germanate ferroelectric single crystal. The measurement results of the linear and circular birefringence in the [010] direction at a wavelength of 633 nm under the influence of an electric field are presented. Gyration–electric field hysteresis loops at alternative crystal positions in the polarization system have been used to determine the...
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LINEAR CHARACTERISTICS OF THE SLOSHING PHENOMENON FOR THE PURPOSE OF ON-BOARD SHIP'S STABILITY ASSESSMENT
PublikacjaThe paper presents results of experimental research and numerical simulations of the sloshing phenomenon. The research was focused on computation of the heeling moment affecting stability of a vessel. The proposed linearisation enables application of the results to the assessment of the ship's stability. The dependence of the heeling moment upon localisation of a tank in the ship's hull is analysed. The heeling moment obtained...
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Thermodynamic Properties of Inorganic Salts in Nonaqueous Solvents. VI. Apparent Molar Volumes, Expansibilities, and Compressibilities of Divalent Transition Metal Ions in Methanol and Dimethylsulfoxide
PublikacjaThe temperature dependence of the density of divalent transition metal perchlorates in dimethylsulfoxide as well as cobalt(II), nickel(II) perchlorates, and copper(II) trifluoromethanesulfonate in methanol was determined. Moreover, sound velocities for solutions of cobalt(II), nickel(II) perchlorates, and copper(II) trifluoromethanesulfonate in methanol have been measured at 298.15 K. From these data, the partial molar volumes,...
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Graphs hard-to-process for greedy algorithm MIN
PublikacjaWe compare results of selected algorithms that approximate the independence number in terms of the quality of constructed solutions. Furthermore, we establish smallest hard- to-process graphs for the greedy algorithm MIN.
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Wideband Macromodels in Finite Element Method
PublikacjaThis 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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Structural changes of water caused by non-electrolytes: Volumetric and compressibility approach for urea-like analogues
PublikacjaHydration of thiourea (TU), hydroxyurea (HU, hydroxycarbamide), acetone (AC, 2-propanone) and dimethyl sulfoxide (DMSO) has been investigated with the help of the volumetric and compression measurement. The apparent molar volumes and the apparent molar isentropic (adiabatic) compression have been calculated from the density and speed of sound data at temperatures ranging from 288.15 to 308.15 K at atmospheric pressure (0.1 MPa)....
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Design and Characterization of a Planar Structure Wideband Millimeter-Wave Antenna with Wide Beamwidth for Wearable off-body Communication Applications
PublikacjaThis letter presents the design of a planar single-layer wideband antenna featuring wide beamwidth has well as high and stable in-band gain. The proposed antenna is a planar monopole fed by a bottom-grounded coplanar waveguide to realize wide beamwidth in both the xz- and yz-planes. Simultaneous optimization of all adjustable antenna parameters, carried out at the full-wave electromagnetic simulation level. The constructive interference...
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Compact Dual-Polarized Corrugated Horn Antenna for Satellite Communications
PublikacjaIn this paper, a structure and design procedure of a novel compact dual-polarized corrugated horn antenna with high gain and a stable phase center for satellite communication is presented. The antenna incorporates an Ortho-Mode Transducer (OMT), a mode converter, and a corrugated structure. The compact OMT section is designed to be fed by standard WR-75 waveguides. The proposed compact design utilizes only ten corrugated slots...
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60 GHz Microstrip Van Atta Arrays for Millimeter Wave Identification and Localization
PublikacjaIn this paper performance comparison of co-polarized and cross-polarized microstrip Van Atta arrays working in the 60 GHz frequency range is presented. They can be treated as simple chipless RFID tags with frequency response based identification. Tags with three different nominal resonance frequencies of 57, 62 and 67 GHz are designed by scaling optimized base model. Designed 62 GHz co-polarized and cross-polarized arrays with...
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A DFT+U study of carbon nanotubes under influence of a gate voltage
PublikacjaA possibility of appearance of antiferromagnetic ordering in armchair carbon nanotubes and graphene is studied using density functional theory within a DFT+U approach. It is shown that the Coulomb repulsion between electrons in the -orbitals of graphene would need to reach a threshold value of ,...
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Polymer based thick films - material quality and interface resistance evaluation
PublikacjaThe properties of polymer based thick film layers mede using different resistive pastes and dipping silvers have been studied. The composite of carbon and graphite (C/Gr) conducting particles suspended in different polymer vehicles were used for preparation resistive layers. Interface resistance Rc created between dipping silver (DiAg) contact layer and resistive layer was determined from the surface potential distribution measurements...
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The influence of the substrate temperature on the preparation of DNA films for studies under vacuum conditions
PublikacjaExperiments were carried out to determine the dependence of the physical form of supercoiled DNA films on the initial temperature of the substrate. Such films are often used in irradiation experiments involving low energy particles, like electrons or photons. In order to obtain absolute values for cross sections for such experiments, the spatial distribution of the sample in the film has to be well estimated. These investigations...
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Import Intensity of Production, Tasks and Wages: Microlevel Evidence for Poland.
PublikacjaObjective: This article relates to recent literature on labour market consequences of production fragmentation within Global Value Chains, analysed in the presence of workers’ heterogeneity and differences in the task content of jobs. The main aim is to assess if there is a relationship between wages of Polish workers and the degree of Polish production dependence on imported inputs. Research Design & Methods: Using microdata from...
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Bounds on isolated scattering number
PublikacjaThe isolated scattering number is a parameter that measures the vulnerability of networks. This measure is bounded by formulas de- pending on the independence number. We present new bounds on the isolated scattering number that can be calculated in polynomial time.
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Bounds on isolated scattering number
PublikacjaThe isolated scattering number is a parameter that measures the vulnerability of networks. This measure is bounded by formulas de- pending on the independence number. We present new bounds on the isolated scattering number that can be calculated in polynomial time.
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Sensorless Control of Induction Machine Supplied by Current Source Inverter
PublikacjaThe paper describes the voltage control technique of induction machines supplied by a current source inverter. The control system is based on proposed new multi-scalar variables, which are named “r.” The control system contains the output filter capacitor's model. In the sensorless control system the Z type backstepping speed observer was applied. The mathematical dependences are confirmed by simulation and experimental research.
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Lower rim substituted p-tert-butyl-calix[4]arene. Part 17. synthesis, extractive and ionophoric properties of p-tert-butylcalix[4]arene appended with hydroxamix acid moieties
PublikacjaThe synthesis and characterization of four p-tert-butylcalix[4]arene-hydroxamic acidc are reported. The dependence of the metal ion binding, assessed by liquid extraction of the metal nitrates from water into dichloromethane in individual and competitive experiments, on the ligand structure, is presented. The results showed that those ligands could be successfully used in separation process of trnasition and heavy metals often...
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The influence of the thickness, recombination and space charge on the loss of photocurrent in organic semiconductors: an analytical model
PublikacjaWe propose an analytical model of the photocurrent efficiency dependence on the light intensity in organic semiconductors. The influence of the thickness of sample, space charge effects and recombination of charge on the loss of photocurrent has been considered. We demonstrate that the presented model is the enhancement of an analytical model reported recently by Rappaport et al (2005 J. Appl. Phys. 98 033714). The method to identify...
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Extending transition curve in analytical design method
PublikacjaThe paper presents the problem of extending the transitional curves, using for this purpose an analytical design method. The basis for the analysis of numerical calculations were carried out for a wide set of parameters characterizing the standard geometric system. We considered an importance of the size of radius of the circular arc and return angle of route on the obtained results after the formulation of appropriate theoretical...
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A method of determination of electrical conduction mechanisms in complex amorphous materials
PublikacjaA novel approach to determine conduction mechanisms in complex amorphous materials was presented and tested on a real system. In the first step of the presented method, total electrical admittance of the material is analyzed in order to separate a couple of processes, each of which can be described by Jonscher's universal dielectric response. In the following step, a temperature dependence of dielectric response parameters of the...
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High-Efficacy Global Optimization of Antenna Structures by Means of Simplex-Based Predictors
PublikacjaDesign of modern antenna systems has become highly dependent on computational tools, especially full-wave electromagnetic (EM) simulation models. EM analysis is capable of yielding accurate representation of antenna characteristics at the expense of considerable evaluation time. Consequently, execution of simulation-driven design procedures (optimization, statistical analysis, multi-criterial design) is severely hindered by the...
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Evaluation of technical efficiency of heat and electric power generation
PublikacjaThis paper presents an evaluation of technical efficiency and time-dependent changes in productivity of Polish professional electric power and heat&electric power stations by using Data Envelopment Analysis non-parametric method. The research covered the enterprises whose total available electric power amounted to about 98% of that of all professional thermal electric power stations in this country. The analysis has concerned...
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Mixed, quantum-classical description of electron density transfer in the collision process
PublikacjaIn this work, we investigate an ion-atom model describing the time-dependent evolution of electron density during the collision. For a S3+- H system, numerical simulations are based on classical trajectory calculations, and the electron density behaviour is described with the time-dependent Schrödinger equation. We apply the finite difference method to obtain quantitative insights into the charge transfer dynamics, providing detailed...
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Modelowanie ryzyka inwestycyjnego przy użyciu OOBN
PublikacjaCelem artykułu jest przedstawienie sieci Bayesa zorientowanych obiektowo (ang. Object Oriented Bayesian Networks – OOBN). Umożliwiają one dekompozycję złożonego modelu na pojedyncze obiekty, które reprezentują nie tylko różne grupy zagadnień, ale także pozwalają na modelowanie zależności czasowychmiędzy obiektami.Wykorzystanie obiektowych sieci Bayesa zaprezentowano na przykładzie projektu rewitalizacji. Przedstawiono zarówno wady,...
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A low-voltage CMOS negative impedance converter for analogue filtering applications
PublikacjaLow-voltage high-frequency continuous-time filters are still required in many applications and are the subject of continuing research. There are many techniques to realize integrated filters, including OTA C, Opamp RC and MOSFET-C-Opamp. The latter two show high dynamic range at low supply voltage, but their frequency operating range is usually limited to several megahertz. Transconductance filters are dedicated to higher frequencies....
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Algorithms for Ship Movement Prediction for Location Data Compression
PublikacjaDue to safety reasons, the movement of ships on the sea, especially near the coast should be tracked, recorded and stored. However, the amount of vessels which trajectories should be tracked by authorized institutions, often in real time, is usually huge. What is more, many sources of vessels position data (radars, AIS) produces thousands of records describing route of each tracked object, but lots of that records are correlated...
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Study on Speech Transmission under Varying QoS Parameters in a OFDM Communication System
PublikacjaAlthough there has been an outbreak of multiple multimedia platforms worldwide, speech communication is still the most essential and important type of service. With the spoken word we can exchange ideas, provide descriptive information, as well as aid to another person. As the amount of available bandwidth continues to shrink, researchers focus on novel types of transmission, based most often on multi-valued modulations, multiple...
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Design of a compact planar transmission line for miniaturized rat-race coupler with harmonics suppression
PublikacjaThis paper presents an elegant yet straightforward design procedure for a compact rat-race coupler (RRC) with an extended harmonic suppression. The coupler’s conventional λ/4 transmission lines (TLs) are replaced by a specialized TL that offers significant size reduction and harmonic elimination capabilities in the proposed approach. The design procedure is verified through the theoretical, circuit, and electromagnetic (EM) analyses,...
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Broadband Compact Single-Layer Magic-T Junction with Separation of DC Signals between All Ports
PublikacjaA novel structure for a four-port microstrip magic-T junction is presented. The device is composed of microstrip and slotline circuits etched onto two sides of a dielectric substrate. The device is extremely compact and occupies an area more than three times smaller than similar structures recently reported in the literature. The novelty of the device lies in the use of microstrip/slotline transitions for both input ports: summation...
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Adaptive Method of Raster Images Compression and Examples of Its Applications in the Transport Telematic Systems
PublikacjaThe paper presents a concept and exemplary application of an adaptive method of compression of raster images which may be applied, i.a. in ITS systems. The described method allows to improve the efficiency of systems belonging to ITS category, which require transmission of large volumes of image data through telecommunications networks. The concept of the adaptive method of compression of raster images described in the paper uses...
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Microstructure and Dielectric Properties of Barium-vanadate Glasses
PublikacjaThe ac and dc conductivity in barium-vanadate glasses was investigated as a function of temperature and frequency with the use of impedance spectroscopy. The topography and microstructure of glasses were investigated by the means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. The XRD results show that all samples are amorphous but microscopy investigation reveals that glasses with greater amount of V2O5...
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Positive solutions to fractional differential equations involving Stieltjes integral conditions
PublikacjaIn this paper, we investigate nonlocal boundary value problems for fractional differential equations with dependence on the first-order derivatives and deviating arguments. Sufficient conditions which guarantee the existence of at least three positive solutions are new and obtained by using the Avery–Peterson theorem. We discuss problems (1) and (2) when argument b can change the character on [0, 1], so in some subinterval I of...
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The Impact of Forms of Buildings on the Air Exchange in Their Environment. Based on the Example of Urban Development in Warsaw
PublikacjaPossibilities for energy-efficient, natural ventilation of buildings in an urban environment depend on the airflow around them. This chapter deals with the issue of dependence of air exchange in urban spaces on the building forms used in them and on relative position of these buildings. The authors focused on the problem of air stagnation in dense urban development. This phenomenon increases the energy demand of buildings. The...
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ANALYSIS OF THE IMPACT OF MASS FLOW EXTRACTION ON THE CHANGE OF PARAMETERS IN A LABYRINTH SEAL USING THE STODOLA METHOD
PublikacjaLabyrinth seals are an important element of a steam turbine set design. The use of diagnostic extraction makes it possible to control the operation of a seal by providing information on the thermodynamic parameters along the length of the seal. Diagnostic extraction has a considerable impact on the change of the parameters, the amount of the extracted mass. This article describes the dependence of pressure in the clearance downstream...
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ANALYSIS OF THE IMPACT OF MASS FLOW EXTRACTION ON THE CHANGE OF PARAMETERS IN A LABYRINTH SEAL USING THE STODOLA METHOD
PublikacjaLabyrinth seals are an important element of a steam turbine set design. The use of diagnostic extraction makes it possible to control the operation of a seal by providing information on the thermodynamic parameters along the length of the seal. Diagnostic extraction has a considerable impact on the change of the parameters, the amount of the extracted mass. This article describes the dependence of pressure in the clearance downstream...
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Rynek mocy jako nowy mechanizm rozliczeń w systemie elektroenergetycznym
PublikacjaW artykule opisano rozliczenia w systemie elektroenergetycznym uzależnione od mocy, związane z gwarancją dostawy energii elektrycznej do systemu. Przedstawiono najważniejsze rynkowe mechanizmy mocowe, skupiając się głównie na rozwiązaniach stosowanych w krajach europejskich. Przedstawiono najważniejsze zasady funkcjonowania rynku mocy w Polsce oraz omówiono wyniki pierwszych aukcji na lata 2021-2023.
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Product Graph Invariants with Applications in the Theory of Information
PublikacjaThere are a large number of graph invariants. In the paper, we consider some of them, e.g. the independence and chromatic numbers. It is well know that we cannot efficiently calculate these numbers for arbitrary graphs. In the paper we present relations between these invariants and concepts from the theory of information. Concepts such as source coding and transmission over a noisy channel with zero probability of error are modeled...
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Straightened characteristics of McKendrick-von Foerster equation
PublikacjaWe study the McKendrick-von Foerster equation with renewal (that is the age-structured model, with total population dependent coefficient and nonlinearity). By using a change of variables, the model is then transformed to a standard age-structured model in which the total population dependent coefficient of the transport term reduces to a constant 1. We use this transformation to get existence, uniqueness of solutions of the problem...