Filtry
wszystkich: 10081
wybranych: 8871
-
Katalog
Filtry wybranego katalogu
wyświetlamy 1000 najlepszych wyników Pomoc
Wyniki wyszukiwania dla: Pulse wave analysis
-
Monitoring Steel Bolted Joints during a Monotonic Tensile Test Using Linear and Nonlinear Lamb Wave Methods: A Feasibility Study
PublikacjaThe structural integrity of steel bolted joints may be compromised due to excessive loading. Therefore, condition assessment and the detection of potential defects before they cause a failure have become a major issue. The paper is focused on the condition monitoring of a bolted lap joint subjected to progressive degradation in a tensile test. The inspection used Lamb waves propagated through the overlap area. Wave propagation...
-
Simple Millimeter Wave Identification System Based on 60 GHz Van Atta Arrays
PublikacjaThe paper presents a proof-of-concept of a millimeter-wave identification system based on Van Atta array tags in the 60 GHz band. For interrogation of the tags, a vector network analyzer and a measurement transceiver were employed in alternative test configurations. The design, fabrication and measurements of co- and cross-polarized Van Atta arrays are presented in the paper. They can be treated as simple chipless RFID tags with...
-
Augmentation index, pulse pressure amplification and superoxide anion production in patients with coronary artery disease
Publikacja -
Software-based method of increasing the effective resolution of a measurement chain for a transducer with a pulse frequency output
Publikacja -
A microcontroller system for measurement of three independent components in impedance sensors using a single square pulse
PublikacjaOpracowano nową metodę pomiaru w dziedzinie czasu i wyznaczania trzech składowych elementów modelu czujnika impedancyjnego oraz zaimplementowano ją w inteligentnym czujniku impedancji sterowanym 8-bitowym mikrokontrolerem. Metoda bazuje na pobudzeniu dzielnika napięciowego składającego się z rezystora pełniącego funkcję konwertera prąd na napięcie i z czujnika impedancji pojedynczym impulsem prostokątnym o czasie trwania T bezpośrednio...
-
A Single-Carrier-Based Pulse-Width Modulation Template for Cascaded H-Bridge Multilevel Inverters
PublikacjaMultiplicity of the triangular carrier signals is a criterion for the extension of sinusoidal pulsewidth modulation, SPWM, to a number of output voltage levels per phase-leg in cascaded H-bridge (CHB) multilevel inverter (MLI). Considering medium and high voltage applications where appreciable number of output voltage levels from CHB MLI is needed, commensurate high number of carrier signals in either classical level- or phase-shifted...
-
5G Millimeter Wave Network Optimization: Dual Connectivity and Power Allocation Strategy
PublikacjaThe fifth generation (5G) of mobile networks utilizing millimeter Wave (mmWave) bands can be considered the leading player in meeting the continuously increasing hunger of the end user demands in the near future. However, 5G networks are characterized by high power consumption, which poses a significant challenge to the efficient management of base stations (BSs) and user association. Implementing new power consumption and user...
-
Circularly Polarized Antenna Array design with the Potential of Gain-Size Trade-off and Omnidirectional Radiation for Millimeter-Wave Small Base Station Applications
PublikacjaThis paper presents the design and validation of a slot-patch-hybrid circularly polarized antenna array for 28 GHz millimeter (mm) wave (mm-wave) applications. The proposed design has a simple geometry that facilitates the fabrication process, which is otherwise a challenging task due to the sub-mm dimensions of the circuit in the mm-wave band. In the proposed structure, aperture-coupled series slot-fed array is utilized to excite...
-
Informal employment in Poland: an empirical spatial analysis
PublikacjaThe main goal of our article is to bridge the gap in the regional analysis of informal employment in Poland and in particular to indicate the propensity for informal work in the working-age population, to test if informal activities are typical for marginalized people (less educated, unemployed, older) and to identify the regional and spatial heterogeneity in the propensity. We use data from the ‘Human Capital Balance 2010–2014’...
-
Frequency Selective Surface Based MIMO Antenna Array for 5G Millimeter-Wave Applications
PublikacjaAbstract: In this paper a radiating element consisting of a modified circular patch is proposed for MIMO arrays for 5G millimeter-wave applications. The radiating elements in the proposed 2×2 MIMO antenna array are orthogonally configured relative to each other to mitigate mutual coupling that would otherwise degrade the performance of the MIMO system. The MIMO array was fabri-cated on Rogers RT/Duroid high frequency substrate...
-
Detailed investigation of the phase transition inKxP4W8O32and experimental arguments for a charge density wave due to hidden nesting
PublikacjaDetailed structural and magnetotransport properties of monophosphate tungsten bronze Kx(PO2)4(WO3)8 single crystals are reported. Both galvanomagnetic and thermal properties are shown to be consistent with a charge density wave electronic transition due to hidden nesting of the quasi-1D portion of the Fermi surface. We also observe the enhancement of electronic anisotropy due to reconstruction of the Fermi surface at the Peierls...
-
Wave-induced stress and breaking of sea ice in a coupled hydrodynamic–discrete-element wave–ice model
Publikacja -
Wave-induced stress and breaking of sea ice in a coupled hydrodynamic–discrete-element wave–ice model
Publikacja -
Wave-induced stress and breaking of sea ice in a coupled hydrodynamic–discrete-element wave–ice model
Publikacja -
An Analysis of Scattering from Ferrite Post of Arbitrary Convex Cross Section with the Use of Field Matching Method
PublikacjaA problem of electromagnetic wave scattering from ferrite post is presented. The post is assumed to be located in closed areas as waveguide junction, or in open area illuminated by a plane wave. The object is of arbitrary convex cross section and the method of analysis is semi-analytical, based on the direct field matching technique.
-
Wideband High-Gain Low-Profile Series-Fed Antenna Integrated with Optimized Metamaterials for 5G millimeter Wave Applications
PublikacjaThis paper presents a series-fed four-dipole antenna with a broad bandwidth, high gain, and compact size for 5G millimeter wave (mm-wave) applications. The single dipole antenna provides a maximum gain of 6.2 dBi within its operational bandwidth, which ranges from 25.2 to 32.8 GHz. The proposed approach to enhance both gain and bandwidth involves a series-fed antenna design. It comprises four dipoles with varying lengths, and a...
-
Impact of diffusion coefficient averaging on solution accuracy of the 2D nonlinear diffusive wave equation for floodplain inundation
PublikacjaIn the study, the averaging technique of diffusion coefficients in the two-dimensional nonlinear diffusive wave equation applied to the floodplain inundation is presented. As a method of solution, the splitting technique and the modified finite element method with linear shape functions are used. On the stage of spatial integration, it is often assumed that diffusion coefficient is constant over element and equal to its average...
-
Interaction of light with standing cylindrical ultrasonic wave in air
Publikacja -
Lamb wave propagation in a single lap adhesive joint
Publikacja -
Bolted Joint Monitoring Using the Elastic Wave Propagation
Publikacja -
Towards automated full-wave design of microwave structures
PublikacjaArtykuł przedstawia problematykę automatycznego projektowania układów mikrofalowych i jego znaczenie. przedstawia stan rynku narzędzi projektowania, pojawiąjące się rozwiązania i przyszłe trendy.
-
EFFECTS OF BOUNDARY CONDITION EVALUATION ON DESIGN WAVE MODELING
Publikacja -
Phase-decoupled refraction–diffraction for spectral wave models
Publikacja -
Wind wave variability in Hornsund fjord, west Spitsbergen
Publikacja -
Influence of vortices on a progressive quasi-plane acoustic wave
PublikacjaMetoda separacji składowych przepływu ogólnego doprowadza do powstania układów równań dla wszystkich możliwych typów ruchu. Szczególny przypadek oddziaływań dotyczy rozpraszania fali akustycznej na wirach. W rezultacie separacji układu bilansu powstają równania pierwszego rzędu względem czasu dla fal akustycznych o przeciwnych kierunkach propagacji. Zasugerowane są ilustracje.
-
Dependence of harmonic generation on primary wave pressure distribution
PublikacjaPraca dotyczy numerycznego badania zagadnienia wytwarzania harmonicznych ciśnienia podczas rozchodzenia się fal o skończonej amplitudzie, promieniowanych przez źródła kołowe o różnych rozkładach. Model matematyczny zbudowano w oparciu o równanie KZK. Do numerycznego rozwiązania problemu zastosowano metodę bilansu harmonicznych i metodę różnic skończonych. Analizowano zmiany składowych harmonicznych ciśnienia w obrębie wiązki akustycznej....
-
Testing oscillators by waveform comparison with the ideal sine-wave
PublikacjaW kontekście oscylacyjnej metody testowania zaproponowano prostą i mało kosztowną metodę testowania oscylatorów poprzez porównanie fragmentu generowanego przebiegu z wzorcowym przebiegiem sinusoidalnym. Metoda bazuje na odejmowaniu dwu sygnałów zmodulowanych techniką sigma-delta za pomocą subtraktora wykorzystujacego nadpróbkowanie i kształtowanie szumów. Sygnaturą uszkodzeń jest wartość średnia 1 bitowego strumienia danych, wyznaczana...
-
Flexural shera wave propagation in cracked composite beam.
PublikacjaW pracy przedstawiono model i wyniki analizy wpływu peknięcia na propagacje fali gietno-scinajacej w belce kompozytowej.
-
Acoustic streaming caused by modulated sound and wave packets.
PublikacjaRozpatruje się powstanie pola wirowego na skutek nieliniowej propagacji fali akustycznej w środowiskach z lepkością. Teoria odwołuje się do fal akustycznych nieokresowych, w odróżnieniuod teorii klasycznej. Obliczenia numeryczne na podstawie nowych wzorów są porównywane z wynikami teorii klasycznej.
-
Elastic wave propagation software in structural health monitoring
PublikacjaW pracy omówiono program do analizy propagacji fal spręzytsych w lementach konstrukcji z uszkodzeniami, oraz omówiono mozliwości jego wykorzystania do monitorowania stanu konstrukcji.
-
Wave propagation in a sensor/actuator diffusion bond model
Publikacja -
Numerical modeling of the nonlinear wave propagation in a bubble layer
PublikacjaRozważano zagadnienie propagacji fali wewnątrz warstwy z pęcherzykami. Omówiono model matematyczny, przedstawiono przykładowe wyniki badań teoretycznych. Analizowano zmiany ciśnienia wewnątrz warstwy, falę odbitą i bieżącą w ośrodku otaczającym, badano gęstość widmową mocy. Badania teoretyczne przeprowadzono dla różnych grubości warstwy, koncentracji pęcherzyków i wartości parametrów fali padającej.
-
Search for the fundamental solution to the vector acoustic wave equations
PublikacjaCzasowo-przestrzenna funkcja Greena pola swobodnego jest dobrze znanym rozwiązaniem podsta-wowym skalarnego niejednorodnego równania falowego. Wyraża ona odpowiedź ośrodka płynnego na punktowe zaburzenie o symetrii sferycznej. Odpowiedź ośrodka na zaburzenie wektorowe nie jest tak oczywista. Artykuł przedstawia oryginalne podejście do problemu, polegające na systematycznej, szcze-gółowej weryfikacji hipotetycznych rozwiązań skalarnych...
-
Application of wave spectra to mathematical model of multihull vessel
PublikacjaDynamiczne układy mechaniczne reprezentujące obiekty pływające są ściśle związane z procesami stochastycznymi. Zmienne stanu i parametry wejścia w tych modelach mają charakter probabilistyczny. Modele matematyczne takich układów są reprezentowane przez układy stochastycznych równań różniczkowych tworząc układy równań ''Ito''. W artykule zostały wyznaczone współczynniki transmitancji dla wybranych trzech widm falowania: Kongresu...
-
Theoretical Model of Acoustic Wave Propagation in Shallow Water
PublikacjaThe work is devoted to the propagation of low frequency waves in a shallow sea. As a source of acoustic waves, underwater disturbances generated by ships were adopted. A specific feature of the propagation of acoustic waves in shallow water is the proximity of boundaries of the limiting media characterised by different impedance properties, which affects the acoustic field coming from a source situated in the water layer “ deformed”...
-
Modelling of in-plane wave propagation in a plate using spectral element method and Kane-Mindlin theory with application to damage detection
PublikacjaThis paper presents results of experimental and numerical analyses of in-plane waves propagatingin a 5 mm-thick steel plate in the frequency range of 120-300 kHz. For such a thickness/frequency ratio,extensional waves reveal dispersive character. To model in-plane wave propagation taking into account thethickness-stretch effect, a novel 2D spectral element, based on the Kane-Mindlin theory, was formulated. Anapplication of in-plane...
-
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...
-
Continuum wave functions for estimating the electric dipole moment: Calculation based on a multiconfiguration Dirac-Hartree-Fock approximation
PublikacjaThe multiconfiguration Dirac-Hartree-Fock method is employed to calculate the continuum electron wave functions, which are then used to estimate their contribution to the atomic electric dipole moment (EDM) of 129Xe. The EDM arises from (P,T)-odd electron-nucleon tensor-pseudotensor and pseudoscalar-scalar interactions, the nuclear Schiff moment, the interaction of the electron electric dipole moment with nuclear magnetic moments,...
-
Numerical Analysis of Impact of Energy Buoy Anchoring Configurations on its Motion and Efficiency
PublikacjaThis paper presents a numerical analysis of the impact of energy buoy mooring configurations on its movement on the wave and effectiveness. The method used to analyse the buoy movement modelling in six degrees of freedom was described in a paper presented at the Conference 2011. Simulations of the buoy movement in regular wave and power calculations were conducted for several configurations of anchoring systems and position of...
-
Analog modelling in qualitative analysis of vibration propagation
PublikacjaThe theory of dynamic systems is usually used to model the real systems. The models are based on solving ordinary differential equations, partial or difference, which enable obtaining the relation between input signal and the system response (output signal). The analogy between those models and generalized dynamic systems or control systems can be practically used. Vibration propagation can be described in a similar way as the...
-
space-vector pulse width modulation for three-level npc converter with the neutral point voltage control
PublikacjaPrzedstawiono strategię modulacji PWM dla trójpoziomowych falowników NPC z predykcją i kompensacją asymetrii rozkładu napięcia na kondensatorach obwodu pośredniczącego
-
Analysis
PublikacjaNew food products and diverse formulations containing the regulated steviol glycoside(s) as well as Stevia extracts or Stevia leaves have been brought on the global market. The upcoming multitude of such food products, but also their falsification and adulteration, does have impact on food analysis. Robust high-throughput methods that cope with different food matrices are required for food control to ensure food safety. The analysis...
-
Electromagnetic plane wave scattering from a cylindrical object with an arbitrary cross section using a hybrid technique
PublikacjaA hybrid technique combining finite-element and mode-matching methods for the analysis of scattering problems in open and closed areas is presented. The main idea of the analysis is based on the utilization of the finite-element method to calculate the post impedance matrix and combine it with external excitation. The discrete analysis, which is the most time- and memory-consuming, is limited here only to the close proximity of...
-
Monitoring the fracture process of concrete during splitting using integrated ultrasonic coda wave interferometry, digital image correlation and X-ray micro-computed tomography
PublikacjaThe paper deals with the continuous-time monitoring of mechanical degradation in concrete cubes under splitting. A series of experiments performed with integrated coda wave interferometry (CWI) and digital image correlation (DIC), supported with X-ray micro-computed tomography (micro-CT) is reported. DIC and micro-CT techniques were used to characterize the fracture process in detail. CWI method was proved to be effective in the...
-
Metamaterial-Based Series-Fed Antenna with High Gain and Wideband Performance for Millimeter Wave Spectrum Applications
PublikacjaThis paper presents a high-gain, wideband series-fed antenna designed for 5G millimeter-wave (MMW) applications. The structure employs a substrate-integrated waveguide (SIW)-based power splitter and metamaterials (MMs). The power divider functions effectively at 27.5 GHz, exhibiting an impedance bandwidth from 26.9–28.6 GHz. The series-fed dipole is assembled on the SIW-based power splitter, incorporating four dipoles with varying...
-
Finite element modelling of a historic church structure in the context of a masonry damage analysis
PublikacjaThe paper includes a case study of modelling a real historic church using the finite element method (FEM) based on laser scans of its geometry. The main goal of the study was the analysis of the causes of cracking and crushing of masonry walls. An FEM model of the structure has been defined in ABAQUS. A non-linear dynamic explicit analysis with material model including damage plasticity has been performed. A homogenization procedure...
-
Combined thrust radial bearing of a submarine main shaft – Design and analysis of failure
PublikacjaThis paper presents an analysis of the combined thrust radial bearing of a submarine propulsion shaft. The lubrication system of the bearing is based on a fixed ring. The efficiency of the lubrication system depends on the shaft speed and temperature, which affects oil viscosity. In turn, the thrust bearing load also depends on the rotational speed of the shaft, because as the speed increases, the drag of the ship increases simultaneously,...
-
Cascading transitions toward unconventional charge density wave states in the quasi-two-dimensional monophosphate tungsten bronze P4W16O56
PublikacjaSingle crystals of the m = 8 member of the low-dimensional monophosphate tungsten bronzes (PO2)4(WO3)2m family were grown by chemical vapour transport technique and the high crystalline quality obtained allowed a reinvestigation of the physical and structural properties. Resistivity measurements revealed three anomalies at TC1 = 258 K, TC2 = 245 K and TC3 = 140 K, never observed until now. Parallel X-ray diffraction investigations...
-
Numerical modelling of conical wave formation in multimode optical fibers
Publikacja -
Radio wave propagation conditions for terrestrial radiocommunications in the EHF band
Publikacja