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Wyniki wyszukiwania dla: NONAUTONOMOUS DIFFERENTIAL EQUATIONS
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Local buckling of thin-walled channel member flange made of aluminum alloy
PublikacjaThe paper deals with local stability of the thin-walled compressed flange of channel columns and beams made of aluminum alloy. The aim of paper is to find critical stress of local buckling of the flange member taking into account the web-flange interaction in linear and nonlinear elastic range of the member material. The governing differential equation of the problem is derived with aid of the principle of stationary total potential...
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A DSC and NMR-Relaxation study of the molecular mobility of water protons interacting with chemically modified starches
PublikacjaChanges in the mobility of water protons in the chemically modified starches (CMS)–water system are studied by differential scanning calorimetry and NMR relaxation. The amounts of unfrozen water at negative temperatures and additional (after gelation) unfrozen for CMS are lower than those for native starch. The proton spin–spin relaxation time T2 for CMS samples, conventionally attributed to the water fraction in starch granules,...
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Luminescent properties of Ln3+ doped tellurite glasses containing AlF3
PublikacjaThe low-phonon energy tellurite glasses TeO2-BaO-Bi2O3 and TeO2-BaO-Bi2O3-AlF3 triply doped with Eu3+, Tb3+, Tm3+ ions in two different molar ratios were synthesized using melt-quenching technique. Their structure and luminescence properties were widely investigated by X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and Photoluminescence Spectroscopy (PL). The luminescence...
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The influence of thermal conditions on V2O5 nanostructures prepared by sol-gel method
PublikacjaThis work presents the result of structure investigations ofV 2O5 nanorods grown from thin films and powders prepared by sol-gel method. To examine the best temperature of nanorods crystallization, thin films deposited by spin-coating method on quartz glass or silicon substrates and bulk xerogel powders were annealed at various temperatures ranging from 100∘C to 600∘C. The structure of the samples was characterized by X-ray diffraction...
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The consideration to the dynamic systems parameter identification
PublikacjaIn this paper, a concept for continuous-time dynamic systems parameter identification using modulating function approach is presented. It refers to linear as well as selected non-linear systems. It shows the possibility of direct application without converting differential equation. In particular cases direct application can decrease the amount of computation in non-linear system identification, which generally requires Fourier...
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Comparative molecular modelling of biologically active sterols
PublikacjaMembrane sterols are targets for a clinically important antifungal agent – amphotericin B. The relatively specific antifungal action of the drug is based on a stronger interaction of amphotericin B with fungal ergosterol than with mammalian cholesterol. Conformational space occupied by six sterols has been defined using the molecular dynamics method to establish if the conformational features correspond to the preferential interaction...
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A New Coupler Concept for Contactless High-Speed Data Transmission Monitoring
PublikacjaThis paper presents a new concept of a couplerthat can be applied to high-speed data transmission contactlessmeasurements. The proposed approach is dedicated for differentialsignal transmission monitoring in microstrip coupled lineson printed circuit boards (PCBs). The coupler, produced on aseparate PCB, is overlayed on the transmission line with thedifferential signal and delivers decoupled differential signal tothe main measurement...
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Studies on the influence of β-cyclodextrin derivatives on the physical stability of famotidine
PublikacjaThe usage of Fourier transform infrared spectroscopy, near infrared spectroscopy, differential scanning calorimetry and microscopy is presented in this work focused on the exploration of the effect of CD on the physical stability of famotidine (FAM). The most significant information was achieved by analysis of the second derivatives ofnear infrared (NIR) spectra recorded. Changes in the shape of spectra derivatives allow...
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Application of vibrational spectroscopy, thermal analyses and X-Ray diffraction in the rapid evaluation of the stability in solid-state of ranitidine, famotidine and cimetidine
PublikacjaThis paper reports the study on applicability of Fourier transform infrared (FTIR), near-infrared (NIR) and Raman spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) for the estimation of the chemical stability and photostability of histamine H2-receptor antagonist substances. Ranitidine hydrochloride (RAN), famotidine (FAM) and cimetidine (CIM) were tested and differences in sensitivity were measured...
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Heteroleptic tri-tert-butoxysilanethiolate complexes of manganese(II) - thermal studies
PublikacjaThe thermal behavior of Mn(II) silanethiolate series [Mn(SR)2L(MeOH)n], where R=SSi(OBut)3, L=heterocyclic nitrogen base and n=0, 1 or 2 has been comparatively investigated using differential scanning calorimetry (DSC), thermogravimetry (TG) and TG-infrared spectoscopy (IR) techniques. The TG curves indicate the differences in the thermal decomposition due to presence of distinct N-donor ligands and labile MeOH molecules coordinated...
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Low-energy positron collisions with water: elastic and rotationally inelastic scattering
PublikacjaDifferential, integral and momentum transfer cross sections for the vibrationally elastic and rotationally inelastic scattering of positrons from water at low collision energy (E ≤ 10 eV) are reported. Several models within the R-matrix method are used to compute the body-fixed T-matrices, while the scattering calculations are performed within the fixed-nuclei approximation corrected with the standard Born-closure formula. These...
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Use of Ginger Nanofibers for the Preparation of Cellulose Nanocomposites and Their Antimicrobial Activities
PublikacjaHere, we report, for the first time, the isolation of ginger nanofibers (GNF) from ginger rhizomes spent by acid hydrolysis and followed by high-pressure homogenization. Scanning electron microscopy was utilized to identify the surface morphology of the GNF and the widths ranged between 130 to 200 nm. Structural analysis of GNF was identified by Fourier transform infrared spectroscopy, Differential scanning calorimetry, and X-ray...
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Low energy inelastic electron scattering from carbon monoxide: I. excitation of the a3Π, a’3Σ+ and AΠ1 electronic states.
PublikacjaDifferential scattering cross sections for electron excitation of the three lowest excited electron states of carbon monoxide are obtained experimentally using low-energy electron energy-loss spectroscopy and theoretically using the R-matrix method. The incident electron energies range from near-threshold of 6.3 eV to 20 eV. Experimental scattering angles range from 20◦ to 120◦. The normalization of the experimental cross sections...
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Flexomagnetic response of buckled piezomagnetic composite nanoplates
PublikacjaIn this paper, the equation governing the buckling of a magnetic composite plate under the influence of an in-plane one-dimensional magnetic field, assuming the concept of flexomagnetic and considering the resulting flexural force and moment, is investigated for the first time by different analytical boundary conditions. To determine the equation governing the stability of the plate, the nonlocal strain gradient theory has been...
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Investigation of Liquid–Gas Flow in a Horizontal Pipeline Using Gamma-Ray Technique and Modified Cross-Correlation
PublikacjaThis article presents the application of the radioisotope absorption method in the study of two-phase water–air flow in a horizontal pipe. The measurement principle and the test stand are briefly described. The main part of the article presents the signal analysis methods applied to data obtained from scintillation detectors. Because these signals are mostly stochastic waveforms, they were analyzed statistically using the cross-correlation...
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The dynamic signature verification using population-based vertical partitioning
PublikacjaThe dynamic signature is an attribute used in behavioral biometrics for verifying the identity of an individual. This attribute, apart from the shape of the signature, also contains information about the dynamics of the signing process described by the signals which tend to change over time. It is possible to process those signals in order to obtain descriptors of the signature characteristic of an individual user. One of the methods...
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Autonomous Control of the Underwater Remotely Operated Vehicle in Collision Situation with Stationary Obstacle
PublikacjaThe article considers the problem of autonomous control of the underwater remotely operated vehicle mini Remotely Operated Vehicle (ROV) in a collision situation with a stationary obstacle. The control of the collision avoidance process is presented as a synthesis of fuzzy proportional-differential controllers for the control of distance and orientation concerning the detected stationary obstacle. The control of the submergence...
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The Suzuki model of the multipath fading channel
Dane BadawczeThe dataset contains the results of simulations that are part of the research on modelling the multipath fading in the communication channel. The Suzuki fading envelope is generated using the Monte-Carlo simulation (MCS) in the LabVIEW programming environment.
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Robust identification of quadrocopter model for control purposes
PublikacjaThe paper addresses a problem of quadrotor unmanned aerial vehicle (so-called X4-flyer or quadrocopter) utility model identification for control design purposes. To that goal the quadrotor model is assumed to be composed of two abstracted subsystems, namely a rigid body (plant) and four motors equipped with blades (actuators). The model of the former is acquired based on a well-established dynamic equations of motion while the...
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NUMERICAL SIMULATION OF CRATER CREATING PROCESS IN DYNAMIC REPLACEMENT METHOD BY SMOOTH PARTICLE HYDRODYNAMICS
PublikacjaA theoretical base of SPH method, including the governing equations, discussion of importance of the smoothing function length, contact formulation, boundary treatment and finally utilization in hydrocode simulations are presented. An application of SPH to a real case of large penetrations (crater creating) into the soil caused by falling mass in Dynamic Replacement Method is discussed. An influence of particles spacing on method...
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Novel Analytic-Numerical Model of Free Convection: with Leading Edge Considered
PublikacjaA novel solution of the free convection boundary problem is represented in analytical form for velocity and temperature for an isothermal vertical plate, as an example. These fields are built as a Taylor Series in the x coordinate with coefficients as functions of the vertical coordinate (y). We restrict ourselves by cubic approximation for both functions. The basic Navier-Stokes and Fourier-Kirchhoff equations and boundary conditions...
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Vibration and buckling characteristics of nonlocal beam placed in a magnetic field embedded in Winkler–Pasternak elastic foundation using a new refined beam theory: an analytical approach
PublikacjaIn this article, a new refined beam theory, namely one variable first-order shear deformation theory, has been employed to study the vibration and buckling characteristics of nonlocal beam. The beam is exposed to an axial magnetic field and embedded in Winkler–Pasternak foundation. The von Kármán hypothesis along with Hamilton’s principle has been implemented to derive the governing equations for both the vibration and buckling...
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On the Nonlinear Effects of Magnetoacoustic Perturbations in Optically Thin Quasi-Isentropic Plasmas
PublikacjaNonlinear effects of planar magnetosound perturbations in a plasma are discussed. Plasma is non-adiabatic due to optically thin radiation and external heating. For these reasons, thermal instability of a plasma may appear which makes it acoustically active. The plasma is assumed to be initially homogeneous ideal gas with infinite electrical conductivity permeated by a straight magnetic field which is orthogonal to the trajectories...
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Finite element modeling of plastic hinges based on ductility demand-capacity method using nonlinear material for dynamic analysis
PublikacjaThe article discusses modeling plastic hinges in reinforced concrete interme-diate supports using finite elements methods. The ductility demand-capacitymethod was used to determine the geometrical parameters of cross-section plas-ticization zones, their ability to move and rotate, as well as their ductility. Dueto the varied geometry and stiffness of the supports and their nonlinear behav-ior under dynamic load, this method was...
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Effect of Sinusoidal Corrugated Geometries on the Vibrational Response of Viscoelastic Nanoplates
PublikacjaThe vibrational behavior of viscoelastic nanoplates with a corrugated geometry is a key topic of practical interest. This problem is addressed here for wrinkled nanoplates with small corrugations related to incorrect manufacturing. To this end, a new One-Variable First-order Shear Deformation plate Theory (OVFSDT) is proposed in a combined form with a non-local strain gradient theory. The Kelvin–Voigt model is employed to describe...
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On existence and uniqueness of weak solutions for linear pantographic beam lattices models
PublikacjaIn this paper, we discuss well-posedness of the boundary-value problems arising in some “gradientincomplete” strain-gradient elasticity models, which appear in the study of homogenized models for a large class ofmetamaterials whosemicrostructures can be regarded as beam lattices constrained with internal pivots. We use the attribute “gradient-incomplete” strain-gradient elasticity for a model in which the considered strain energy...
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Nonlinear phenomena of small-scale sound in a gas with exponential stratification
PublikacjaThe nonlinear dynamics of perturbations, quickly varying in space, with comparatively large characteristic wavenumbers k: k>1/H, is considered. H is the scale of density and pressure reduction in unperturbed gas, as the coordinate (H is the so-called height of the uniform equilibrium gas). Coupling nonlinear equations which govern the sound and the entropy mode in a weakly nonlinear flow are derived. They describe the dynamics...
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Balance error generated by numerical diffusion in the solution of Muskingum equation
PublikacjaIn the paper the conservative properties of the lumped hydrological models with variable parameters are discussed. It is shown that in the case of the non-linear Muskingum equation the mass balance is not satisfied. The study indicates that the mass balance errors are caused by the improper form of equation and by the numerical diffusion which is generated in the solution. It has been shown that the classical way of derivation...
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A Measurement-Based Approach for Speed Control of Induction Machines
PublikacjaThis paper presents an approach to design a measurement-based controller for induction machines. The proposed control approach is motivated by the fact that developing an appropriate mechanical model of such induction machines is a challenging task. Since our proposed control methodology is only on the basis of measured data, the controller design does not require any information about the model of the mechanical part. The control...
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Features of Nonlinear Sound Propagation in Vibrationally Excited Gases
PublikacjaWeakly nonlinear sound propagation in a gas where molecular vibrational relaxation takes place is studied. New equations which govern the sound in media where the irreversible relaxation may take place are derived and discussed. Their form depends on the regime of excitation of oscillatory degrees of freedom, equilibrium (reversible) or non-equilibrium (irreversible), and on the comparative frequency of the sound in relation to...
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A Comparison of Simplified Two-dimensional Flow Models Exemplified by Water Flow in a Cavern
PublikacjaThe paper shows the results of a comparison of simplified models describing a two-dimensional water flow in the example of a water flow through a straight channel sector with a cavern. The following models were tested: the two-dimensional potential flow model, the Stokes model and the Navier-Stokes model. In order to solve the first two, the boundary element method was employed, whereas to solve the Navier-Stokes equations, the...
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On Wrinkling in Sandwich Panels with an Orthotropic Core
PublikacjaThis paper deals with the local loss of stability (wrinkling) problem of a thin facing of a sandwich panel. Classical solutions to the problem of facing instability resting on a homogeneous and isotropic substructure (a core) are compared. The relations between strain energy components associated with different forms of core deformations are discussed. Next, a new solution for the orthotropic core is presented in detail, which...
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AN OVERVIEW OF HEAT TRANSFER ENHANCEMENT BASED UPON NANOPARTICLES INFLUENCED BY INDUCED MAGNETIC FIELD WITH SLIP CONDITION VIA FINITE ELEMENT STRATEGY
PublikacjaThe mathematical model of heat generation and dissipation during thermal energy transmission employing nanoparticles in a Newtonian medium is investigated. Dimensionless boundary layer equations with correlations for titanium dioxide, copper oxide, and aluminium oxide are solved by the finite element method. Parameters are varied to analyze their impact on the flow fields. Various numerical experiments are performed consecutively...
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Global value chains, wages, employment and labour production in China: A regional approach
PublikacjaIn this study we analyse the relationship of trade and global value chains (GVCs) to the labour market in 31 Chinese provinces for 25 sectors, by means of a system of structural equations. We firstly distinguish between provincial value chains (PVCs) and interprovincial value chains (PRVCs) in order to outline their distribution and evolution over time. Then, we investigate to what extent participation in GVCs, PVCs and PRVCs –...
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Analytical design method of reverse curves
PublikacjaThe paper deals with a new approach relating to the design of the region of railway track direction alteration adapted to Mobile Satellite Measurements technique. The method may be particularly useful in situations when both the straights of the route directions cannot be connected in an elementary way using a circular arc with transition curves; this also refers to the application of a compound curve. Thus the only solution becomes...
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Dopants and gas modifiers in ion mobility spectrometry
PublikacjaThe ion mobility techniques, including the most commonly used drift-tube ion mobility spectrometry (IMS) and differential mobility spectrometry (DMS), are used successfully for the detection of a wide range of organic compounds in the gas phase. In order to improve detection quality, admixtures are added to gas streams flowing through the detector. Dopants mostly prevent the ionization of interfering chemicals however, better detection...
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Isolation and characterization of Acid Soluble Collagen from the Skin of African Catfish (Clarias gariepinus), Salmon (Salmo salar) and Baltic cod (Gadus morhua)
PublikacjaAcid-soluble collagen (ASC) from the fish skin of African catfish (Clarias gariepinus), Salmon (Salmo salar) and Baltic cod (Gadus morhua) was extracted and characterized. The ASC extraction yield was 75%, 73% and 68%, respectively. The denaturation and melting temperatures of African catfish ASC (29.3°C and 100.0°C) were significantly higher than ASC of Salmon and Baltic cod (20.6°C and 90.5°C; 15.2°C and 86.7°C, respectively), assessed...
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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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Permeation and sorption properties of poly(ether-block-amide) membranesfilled by two types of zeolites
PublikacjaThe experimental study of transport properties of mixed matrix membranes (MMMs) based on PEBA-4033 with two types of zeolites is reported. Gas (CO2, O2, N2) and vapor (benzene, toluene, methanol, water) permeation measurements were performed using the differential flow permeameter at temperature of 298.15 K and at atmospheric pressure. Gas/vapor permeation was monitored by measuring the changes of the thermal conductivity of carrier...
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Thermal degradation kinetics of poly(propylene succinate) prepared with the use of natural origin monomers
PublikacjaLinear biobased polyester polyols were prepared with the use of succinic acid and 1,3-pro- panediol (both with natural origin). Tetraisopropyl orthotitanate (TPT) was used as a catalyst. In order to determine the effect of various synthesis temperature conditions on the thermal degradation kinet- ics, nine sequences of temperature conditions were used during two-step polycondensation reaction. Thermogravimetric analysis was conducted...
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A Power-Efficient Digital Technique for Gain and Offset Correction in Slope ADCs
PublikacjaIn this brief, a power-efficient digital technique for gain and offset correction in slope analog-to-digital converters (ADCs) has been proposed. The technique is especially useful for imaging arrays with massively parallel image acquisition where simultaneous compensation of dark signal non-uniformity (DSNU) as well as photo-response non-uniformity (PRNU) is critical. The presented approach is based on stopping the ADC clock by...
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Mathematical modeling and prediction of pit to crack transition under cyclic thermal load using artificial neural network
PublikacjaThe formation of pitting is a major problem in most metals, which is caused by extremely localized corrosion that creates small holes in metal and subsequently, it changes into cracks under mechanical load, thermo-mechanical stress, and corrosion process factors. This research aims to study pit to crack transition phenomenon of steel boiler heat tubes under cyclic thermal load, and mathematical modeling...
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Direct-contact condensation from vapour- gas mixture in a spray ejector condenser for negative CO2 power plant
PublikacjaDirect-contact condensation of vapour containing the inert gas on a spray of subcooled liquid exists in a number of technical applications. For example, it may be found in the nuclear industry (e.g. pressurized jet under normal operating conditions, in safety analyses) or in the chemical industry (e.g. mixing-type heat exchanger, degasser, sea water desalting). The problem is also essential to modelling and analysis of some...
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Thermal properties of strontium–borate glasses and glass-ceramics containing bismuth and vanadium oxides measured with DSC method
Dane BadawczeThermal properties of strontium–borate glasses and glass-ceramics containing bismuth and vanadium oxides was measured by DSC.
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Thermal properties of ceramic Bi2VO5.5 and strontium–borate glass-ceramics containing crystalites of Bi2VO5.5. measured with DSC
Dane BadawczeThermal properties of ceramic Bi2VO5.5 and strontium–borate glass-ceramics containing Bi2VO5.5 crystallites was measured by DSC.
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Continuum orbitals in low energy scattering of electrons from Ar, Kr, Xe, Rn and Og atoms
Dane BadawczeThe dataset includes relativistic continuum electron wave functions (continuum orbitals, continuum spinors) for elastic scattering of electrons from Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn) and Oganesson (Og) atoms, calculated using the Multiconfiguration Dirac-Hartree-Fock method (MCDHF), at very low electron energies (0.0001 - 0.001 eV). Only...
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Asynchronous WAM with Irregular Pulse Repetition
PublikacjaRadiolocation systems for aviation based on Multi-Lateration (MLAT) typically use a set of synchronised ground sensors to receive radio signals broadcast by onboard transmitters. In most cases, the sensor synchronisation in Wide Area Multi-Lateration Systems (WAM) is provided by Global Navigation Satellite System (GNSS) receivers. However, in the case of synchronisation failure, there is still a possibility to estimate the coordinates...
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Mathematical modelling of the overhead contact line for the purpose of diagnostics of pantographs
PublikacjaThe overhead contact line (OCL) is the most effective way for supplying railway electric vehicles. The increase of the speed of the vehicles increases power consumption and requires ensuring proper cooperation of pantographs with OCL. The paper describes the novel mathematical model of the OCL system and the simulation results. The primary objective is a more accurate analysis to increase the reliability of the evaluation of monitoring...
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Geometry Parametric Model Order Reduction with Randomly Generated Projection Bases
PublikacjaIn this work, a reduced-order model for geometry parameters and fast frequency sweep is proposed. The Finite Element Method is used to solve time-harmonic Maxwell’s equations. Taking into account the electromagnetic field does not arbitrarily vary as a function of frequency and geometry parameters, a low dimension system manifold is identified. Thus, the original Finite Element problem can be approximated by a model of reduced...
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Relativity of arithmetic as a fundamental symmetry of physics
PublikacjaArithmetic operations can be defined in various ways, even if one assumes commutativity and associativity of addition and multiplication, and distributivity of multiplication with respect to addition. In consequence, whenever one encounters ‘plus’ or ‘times’ one has certain freedom of interpreting this operation. This leads to some freedom in definitions of derivatives, integrals and, thus, practically all equations occurring in...