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Wyniki wyszukiwania dla: elastic wave propagation
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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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STABILITY AND LOAD BEARING CAPACITY OF A BARS WITH BUILT UP CROSS SECTION AND ELASTIC SUPPORTS
PublikacjaThe present paper is devoted to the numerical analysis and experimental tests of compressed bars with built–up cross section which are commonly used as a top chord of the roof trusses. The significant impact on carrying capacity for that kind of elements in case of out-of-plane buckling is appropriate choice of battens which are used to provide interaction between separate members. Linear buckling analysis results and nonlinear static...
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Comparison of elastic and viscoelastic analysis of asphalt pavement at high temperature
PublikacjaThere are many various rheological models which are used for modeling of asphalt layers in flexible pavement structures. It can be expected that the use of various models may affect different results of mechanical pavement calculations and analysis. The paper presents comparison of the use of Burgers’ and Huet-Sayegh’s viscoelastic models and Hooke’s elastic model to calculate pavement deflections and strains at the bottom of asphalt...
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Bandwidth Dependence of the Propagation Channel in Circular Metallic BAN Environments
PublikacjaIn this paper, the bandwidth dependence of the propagation channel for Body Area Networks (BANs) in circular metallic environments is addressed and models are proposed to evaluate the appropriate short-term fading margins that should be considered as a function of the system bandwidth. The deployment of BANs in metallic indoor environments, such as ships, factories, warehouses and other similar environments, involves additional...
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Modification of Selected Propagation Models in Terms of Path Loss Estimation in Container Terminal
PublikacjaIt 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...
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Deformation of an elastic second gradient spherical body under equatorial line density of dead forces
PublikacjaWe consider deformations of an elastic body having initially a spherical shape. Assumed deformation energy depends on the first and second gradient of displacements. We apply an equatorial line density of dead loads, that are forces per unit line length directed in radial direction and applied along the equator of the sphere. We restrict ourselves our analysis to the case of linearized second strain gradient isotropic elasticity...
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IEEE ANTENNAS AND PROPAGATION MAGAZINE
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Elastic distortional buckling of thin-walled bars of closed quadratic cross-section
PublikacjaIn this study a tin-walled bar with closed quadratic cross-section is considered. The elastic stability of axially compressed bar related to the cross-section distortion is investigated. The governing differential equatio is derived with aid of the principle of stationary potential energy. The critical load for simply supported bar is found in an analytical form and it is copared with the FEM solution. Sufficient accuracy of the...
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Elastic distortional buckling of thin-walled bars of closed quadratic cross-section
PublikacjaIn this study a thin-walled bar with closed quadratic cross-section is considered. The elastic stability of axially compressed bar related to the cross-section distortion is investigated. The governing differential equation is derived with aid of the principle of stationary total potential energy. The critical load for the simply supported bar is found in analytical form and it is compared with the FEM solution. Sufficient accuracy...
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Efficient Complex Root Finding Algorithm for Microwave and Optical Propagation Problems
PublikacjaArticle relates to the use of innovative root finding algorithm (on a complex plane) to study propagation properties of microwave and optical waveguides. Problems of this type occur not only in the analysis of lossy structures, but also in the study of complex and leaky modes (radiation phenomena). The proposed algorithm is simple to implement and can be applied for functions with singularities and branch cuts in the complex plane...
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Elastic electron scattering and vibrational excitation of isoxazole molecules in the energy range from 2 to 20 eV
PublikacjaDifferential cross sections for elastic electron scattering and the excitation of the C-H vibrational modes of isoxazole molecules were measured in the energy range from 2 to 20 eV and over the scattering angle range from 10◦ to 180◦. The cross sections at the scattering angles of and above 90◦ were accessible with the use of a magnetic angle changer. The differential cross sections were integrated to yield integral and momentum...
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Buckling and postcritical behaviour of the elastic infinite plate strip resting on linear elastic foudation
PublikacjaW pracy rozważa się problem von Karmana dla swobodnie podpartego pasma płytowego spoczywającego na sprężystym podłożu i poddanego równomiernie rozłożonemu obciążeniu ściskającemu na krawędzi podparcia. Krytyczne wartości parametrów wyznaczono na podstawie problemu zlinearyzowanego. Stan pokrytyczny badano za pomocą redukcji Liapunowa-Schmidta i twierdzenia Crandalla-Rabinowitza. Wykazano, że istnieje maksymalna częstość fal w kierunku...
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On solvability of initial boundary-value problems of micropolar elastic shells with rigid inclusions
PublikacjaThe 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...
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Damage localisation in a stiffened plate structure using a propagating wave
PublikacjaThe paper presents an application of changes in propagating waves for damage detection in a stiffened aluminium plate. The experimental investigation was conducted on an aluminium plate with riveted two L-shape stiffeners. The wave has been excited with a piezoelectric transducer and measured with the Laser Scanning Doppler Vibrometer. Recorded signals were analysed using the special signal processing techniques developed for damage...
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IEEE Microwave and Guided Wave Letters
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Modeling of the denture’s elastic base
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Protection in elastic optical networks
PublikacjaIn this article, we analyze gains resulting from the use of EON architectures with special focus on transportation of cloud-ready and content-oriented traffic in the context of network resilience. EONs are a promising approach for future optical transport networks and, apart from improving the network spectral efficiency, bring such new capabilities as squeezed protection, which reduces resource requirements in failure scenarios....
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Nonlinear Excitation of the Non-Wave Perturbations by the Magnetoacoustic Waves in the Non-Isentropic Plasma
PublikacjaNonlinear excitation of slow modes by the planar magnetosonic perturbations in a plasma is discussed. Plasma is an open system due to radiation and external heating. This may stipulate enhancement of wave perturbations and hence the acoustical activity of plasma. Plasma is assumed to be a homogeneous ideal gas with infinite electrical conductivity. The straight magnetic field is orthogonal to the velocity of fluid’s...
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Fast Full-Wave Multilevel Zero-Pole Optimization of Microwave Filters
PublikacjaA new concept is proposed for the full-wave computer-aided design of microwave filters. The method consists of two stages and operates on the zeros and poles of the transfer function and their derivatives. These quantities are evaluated from the response computed by a full-wave electromagnetic solver with two levels of accuracy. The two stages make use of different models that are optimized using a low-accuracy electromagnetic...
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Design of OFDM-based radio communication systems for coast-to-sea and coast-to-air propagation environments
PublikacjaIn the paper the study of radio communication system design process for systems based on OFDM transmission is considered. The signal propagation model for 1.4 GHz frequency band is discussed, and the study of signal propagation characteristics, important from the point of view of OFDM system design, is presented. The methodology of OFDM interface design is proposed and some characteristics of the OFDM-based radio communication...
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Scattering and Propagation Analysis for the Multilayered Structures Based on Field Matching Technique
PublikacjaA semi-analytical method is employed to the analysis of scattering and guiding problems in multilayer dielectric structures. The approach allows to investigate objects with arbitrary convex cross section and 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. For the scattering problems the scattered field in the far zone is calculated...
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Low energy elastic scattering of electrons from hexafluoropropene (C3F6)
PublikacjaWe present cross sections from a joint experimental and theoretical study on elastic electron scattering from hexafluoropropene (C3F6) in the gas phase. The experimental results, using low energy electron spectroscopy, were obtained at incident electron energies of 0.5, 1, 1.5, 2, 3, 4, 5, 6, 10, 12, 15 and 20 eV, for scattering angles ranging from 10°to 130°. The theoretical method used in the computation of the integral, momentum...
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Elastic Fender-Dolphin Interaction for Economic Design of Berthing Dolphins
PublikacjaThe study addresses the question of the possible design benefits when considering the interaction between a modern marine modular rubber fender and a steel tubular pile substructure of a berthing dolphin. Absorption of the berthing kinetic energy of the vessel by a dualelasticity pile-fender berthing system is described in detail using the interactive treatment method (ITM). Application of the ITM is illustrated by a calculative...
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Investigation of Continuous Wave Jamming in an IEEE 802.15.4 Network
PublikacjaThis paper presents how continuous wave jamming affects IEEE 802.15.4 network. To this end, an office-based measurement setup has been proposed. Within the measurement area, 25 nodes have been set up in order to create a IEEE 802.15.4 tree-based test network structure. A dedicated jamming device that generates and transmits a continuous wave signal has been developed. Several tests have been conducted and presented to demonstrate...
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Field-induced suppression of charge density wave in GdNiC2
PublikacjaWe report the specific heat, magnetic, magnetotransport, and galvanomagnetic properties of polycrystalline GdNiC 2 . In the intermediate temperature region above T N = 20 K, we observe large negative magnetoresistance due to Zeeman splitting of the electronic bands and partial destruction of a charge density wave ground state. Our magnetoresistance and Hall measurements show that at low temperatures a magnetic field-induced transformation from...
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Analytical Expression for the Time-Domain Green's Function of a Discrete Plane Wave Propagating in the 3-D FDTD Grid
PublikacjaIn this paper, a closed-form expression for the time-domain dyadic Green’s function of a discrete plane wave (DPW) propagating in a 3-D finite-difference time-domain (FDTD) grid is derived. In order to verify our findings, the time-domain implementation of the DPW-injection technique is developed with the use of the derived expression for 3-D total-field/scattered-field (TFSF) FDTD simulations. This implementation requires computations...
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Charge density wave and large nonsaturating magnetoresistance in YNiC2 and LuNiC2
PublikacjaWe report a study of physical properties of two quasi-low-dimensional metals YNiC2 and LuNiC2 including the investigation of transport, magnetotransport, galvanomagnetic, and specific heat properties. In YNiC2 we reveal two subsequent transitions associated with the formation of weakly coupled charge density wave at TCDW=318K and its locking in with the lattice at T1=275K. These characteristic temperatures follow the previously...
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Large thermo-elastic displacement and stability FEM analysis of multilayered plates and shells
PublikacjaThe paper concerns the load capacity analysis of thermally loaded multilayered plates and shells. The multilayered body is treated as an equivalent single layer whose kinematics is consistent with first order shear deformation theory. The authors focus on the thermo-elastic stability problem of the thin-walled structures. The equilibrium paths are traced with the use of Riks-Wempner-Ramm algorithm. By making use of the Tsai-Wu...
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Elastic waves in the railroad track substructures and its surroundings analyzed with non-classical operational methods
PublikacjaWe analyze the propagation of the waves generated by the rolling stock and the interaction of those waves on the medium and its surroundings. We use non-classical operational methods for monitoring construction of the railway infrastructure and for noise damping.
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Propagation Loss and Interference Analysis for 5G Systems in the Context of C-ITS System Implementation
PublikacjaThe article presents the concept of implementing subsequent phases of services for the C-ITS system (the Cooperative Intelligent Transport Systems), based on the European Parliament resolution of March 2018. Next, the 5G systems, in the context of their possible cooperation with C-ITS systems, were discussed. Numerical propagation analysis was performed for V2V and V2I type communication based on two different propagation models....
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Jumping Wave Characteristic during Low Plasticity Burnishing Process
PublikacjaDuring the low plasticity burnishing process of soft materials such as carbon steel with a hardness of up to 40 HRC (Rockwell grade) a raised structure of the material known as the Jumping Wave forms in front of the tool roll. This phenomenon significantly disturbs the burnishing process, but is very poorly described in the literature. This article presents studies of this phenomenon on the example of burnished 1.0562 steel. The...
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High-Resolution Wind Wave Parameters in the Area of the Gulf of Gdańsk During 21 Extreme Storms
PublikacjaThis dataset contains the results of wind-wave parameter modelling in the area of the Gulf of Gdańsk (Southern Baltic). For the simulations, a high resolution SWAN model was used. The dataset consists of the significant wave height, the direction of the wave approaching the shore and the wave period during 21 historical, extreme storms. The storms were selected by an automatic search over the 44-year-long significant wave height...
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On the peculiarities of anti-plane surface waves propagation for media with microstructured coating
PublikacjaWe discuss new type of surface waves which exist in elastic media with surface energy. Here we present the model of a coating made of polymeric brush. From the physical point of view the considered model of surface elasticity describes a highly anisotropic surface coating. Here the surface energy model could be treated as 2D reduced strain gradient continuum as surface strain energy depends on few second spatial derivatives of...
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Study of Non-Newtonian biomagnetic blood flow in a stenosed bifurcated artery having elastic walls
PublikacjaFluid structure interaction (FSI) gained attention of researchers and scientist due to its applications in science felds like biomedical engineering, mechanical engineering etc. One of the major application in FSI is to study elastic wall behavior of stenotic arteries. In this paper we discussed an incompressible Non-Newtonian blood fow analysis in an elastic bifurcated artery. A magnetic feld is applied along x direction. For...
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Propagation Characteristics of Partial Discharges in an Oil-Filled Power Transformer
PublikacjaPower transformers are among the most important assets in the power transmission and distribution grid. However, they suffer from degradation and possible faults causing major electrical and financial losses. Partial discharges (PDs) are used to identify the insulation health status and their degradation level. PDs are incipient, low-magnitude faults caused by localized dielectric breakdown. Those activities emit signals in many...
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Design of an Autonomous IoT Node Powered by a Perovskite-Based Wave Energy Converter
PublikacjaThis paper presents the results of experimental research focused on wave energy harvesting and its conversion to power Internet of Things (IoT) devices. The harvesting and conversion process was performed using a wave energy converter (WEC) consisting of a lead zirconate titanate piezoelectric ceramic perovskite material and a prototype power electronic circuit. The designed WEC was considered as a power supply for an end node...
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System setup and software for cyclic, staircase and square wave voltammetry measurements
PublikacjaHardware dedicated for electrochemical measurement sometimes does not allow performing certain voltammetry experiments. Staircase and square wave voltammetry, techniques which have many advantages comparing with standard voltammetric techniques, are rarely implemented in software controlling electrochemical measuring equipment. These methods, however, can be relatively easy realized with some addition...
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High-resolution wind wave parameters in the area of the Gulf of Gdańsk during 21 extreme storms
Dane BadawczeThis dataset contains the results of wind-wave parameter modelling in the area of the Gulf of Gdańsk (Southern Baltic). For the simulations, a high resolution SWAN model was used. The dataset consists of the significant wave height, the direction of the wave approaching the shore and the wave period during 21 historical, extreme storms. The storms were...
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Non-Perfect Propagation of Information to a Noisy Environment with Self-Evolution
PublikacjaWe study the non-perfect propagation of information for evolving a low-dimensional environment that includes self-evolution as well as noisy initial states and analyse the interrelations between the degree of objectivization and environment parameters. In particular, we consider an analytical model of three interacting qubits and derive its objectivity parameters. The numerical analysis shows that the quality of the spectrum broadcast...
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Simulating coherent light propagation in a random scattering materials using the perturbation expansion
PublikacjaMultiple scattering of a coherent light plays important role in the optical metrology. Probably the most important phenomenon caused by multiple scattering are the speckle patterns present in every optical imaging method based on coherent or partially coherent light illumination. In many cases the speckle patterns are considered as an undesired noise. However, they were found useful in various subsurface imaging methods such as...
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ENHANCED EVAPORATION OF THE DROPLETS OF CONDENSATE IN THE ASYMMETRICAL SHOCK WAVE ZONE
PublikacjaIn the low-pressure part of steam turbine, the state path usually crosses the saturation line in penultimate stages [4,5]. The formation and evolution of these droplets lower the performance of the wet stages of the turbines, and their effects on the efficiency are collectively known as wetness losses [4]. Nowadays, due to work of steam turbines at partial load, process of homogeneous and heterogeneous condensation still is current....
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Bifurcation in von Karman problem for rectangular, thin, elastic plate resting on elastic foundation of Winkler type
PublikacjaPraca poświęcona jest utracie stateczności prostokątnej, cienkiej płyty sprężystej spoczywającej na podłożu liniowo sprężystym typu Winklera. Płyta jest ściskana równomiernie rozłożonymi obciążeniami na dwóch równoległych brzegach. Wyznaczono obciążenia krytyczne, formy utraty stateczności płyty oraz początkowe zachowanie pokrytyczne. Analizę prowadzono za pomocą analizy funkcjonalnej przy zachowaniu precyzyjnego matematycznego...
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Application of the ISE Optimized Proportional Control of the Wave Maker in a Towing Tank
PublikacjaThis paper presents the improvement of the wave maker control system. The wave maker is a facility widely used in hydromechanics laboratories to generate waves in towing tanks. It is equipped with an electrohydraulic drive and an actuator submerged into water. The waves are generated to model the environmental conditions for physical experiments, performed on reduced-scale models of maritime objects. The physical experiments allow...
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Verification of algorithms determining wave loads on support structure of wind turbine
PublikacjaThe offshore wind turbines require determination of wave loads on their support structure. This structure is fixed and, therefore, this problem is reduced to solving only the diffraction problem, which is determined by Laplace equation and conditions on the following boundaries: on the support structure, on the sea free surface and on its bottom, and at infinity on free surface. The linear problem was applied to determine the wave...
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An Experimental Investigation of Pressure Wave Celerity During the Transient Slurry Flow
PublikacjaTransportation of slurries in pressure pipelines is an example of a complex flow due to specific parameters of transported medium. For practitioners, the economy of designing and maintenance is usually the most important factor. For this reason, most of hydrotransport installations are fairly simple; however, they become more vulnerable to negative effects of the transient flow which can occur in pressure pipelines. As the consequence,...
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Beam on elastic foundation with anticlastic curvature: Application to analysis of mode I fracture tests
PublikacjaA first order correction is proposed taking into account both interface elasticity and transverse anticlastic curvature of flexible substrate(s) in the DCB (and related tests). Adherends are represented by Kirchhoff-Love plates, and the interface by Winkler-type elastic foundation. Two functions are introduced, representing evolution of beam deflection along the sample midline and anticlastic curvature along the plate. A method...
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Magnetoelectric, spectroscopic, optical and elastic properties of Co-doped BaTiO3 ceramics
Publikacjahe BaTiO3 perovskite is widely used in the electronic technology due to its dielectric, piezoelectric and ferroelectric properties and is a well-known base for obtaining a promising multifunctional material. In this paper we report the extensive studies on the Co-doped BaTiO3 ceramics for the wide range cobalt content. Full structural characterization of studied samples in a 20–450 K range was provided. The results of research...
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Coda wave interferometry in monitoring the fracture process of concrete beams under bending test
PublikacjaEarly detection of damage is necessary for the safe and reliable use of civil engineering structures made of concrete. Recently, the identification of micro-cracks in concrete has become an area of growing interest, especially using wave-based techniques. In this paper, a non-destructive testing approach for the characterization of the fracture process was presented. Experimental tests were made on concrete beams subjected to mechanical...
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Modelling of elastic response of granular media
PublikacjaW pracy przedstawiono opis gruntowego ośrodka ziarnistego w ujęciu jego nieciągłości.Podano przejście opisu tego ośrodka do opisu ośrodka gruntowego ciągłego. Podano rozwiązania ciągłe stanu naprężenia wg. rozwiązania Mindlina. Podano określenie wartości parametrów sprężystych ośrodka ciągłego przy bardzo małych odkształceniach. Przeanalizowano wpływ różnych czynników na określenie modułu odkształcenia sprężystego. Podano sposób...
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Electron Elastic Collisions with C3F6 Molecule
PublikacjaObliczono różniczkowy i scałkowany przekrój czynny na zderzenia elektronu z molekułą C3F6 w zakresie średnich i wysokich energii (50-1000eV). Obliczenia wykonano stosując metodę atomów niezależnych. Stwierdzono dobrą zgodność z wynikami oszacowanymi na podstawie eksperymentu.