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Search results for: lamb wave
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Numerical investigations of the nonlinear waves generation in a bubble layer
PublicationRozważano zagadnienie propagacji fal różnych częstotliwości wewnątrz warstwy z pęcherzykami. Przedstawiono model matematyczny zjawiska oraz wyniki badań teoretycznych. Badano zmiany widma fali bieżącej i odbitej jak również zmiany amplitud wybranych harmonicznych ciśnienia tych fal w funkcji grubości warstwy i koncentracji pęcherzyków.
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Strongly anisotropic surface elasticity and antiplane surface waves
PublicationWithin the new model of surface elasticity, the propagation of anti-plane surface waves is discussed. For the proposed model, the surface strain energy depends on surface stretching and on changing of curvature along a preferred direction. From the continuum mechanics point of view, the model describes finite deformations of an elastic solid with an elastic membrane attached on its boundary reinforced by a family of aligned elastic...
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A spatio-temporal approach to intersectoral labour and wage mobility
PublicationThe article presents the spatio-temporal approach for intersectoral labor and wage mobility. Analyses of interindustry mobility were performed with the use of general entropy mobility indices (GEMM). Spatio- temporal approach was obtained thanks to the separate measurement of spatial autocorrelation and regression for each set of sectoral wage and employment structure and was conducted in each year of the research period separately....
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A Spatio-temporal Approach to Intersectoral Labour and Wage Mobility
PublicationThe article presents the spatio-temporal approach for intersectoral labor and wage mobility. Analyses of interindustry mobility were performed with the use of general entropy mobility indices (GEMM). Spatio-temporal approach was obtained thanks to the separate measurement of spatial autocorrelation and regression for each set of sectoral wage and employment structure and was conducted in each year of the research period separately....
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Ingoing and outgoing waves in the non-relativistic theory of photoionization
PublicationZastosowano rachunek zaburzeń zależny od czasu do wyprowadzenia wzoru na różniczkowy przekrój czynny na fotojonizację nierelatywistycznego kwantowego układu jednoelektronowego płaską monochromatyczną falą elektromagnetyczną. Pokazano,że pochodzenie oraz asymptotykę tzw. ''funkcji falowej stanu końcowego'', wchodzącej do tego wzoru, można wytłumaczyć bez odwoływania się do kontrowersyjnej argumentacji podanej przez Breita i Bethego.
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SEMG signal database for the automated upper limb rehabilitation process
Open Research DataAn automated rehabilitation device control system requires information about the patient's physiological condition. This is possible thanks to the use of biological feedback in the form of electromyography and surface signals (Surface Electromyography, SEMG).
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Stability of Antiradical Activity of Protein Extracts and Hydrolysates from Dry-Cured Pork Loins with Probiotic Strains of LAB
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Mentor&Student Research Lab: new type of architectural and urban design workshops, new opportunities, valuable results
PublicationThe space around us has significantly changed during last years. Polish cities have undergone a major transformation following political, economical and social transition [8]. Similar change is noticeable at universities and their educational programmes for architecture and spatial planning students. Nowadays designers and activists tackle completely different problems and have different opportunities than their older colleagues...
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Microfluidic Method of Pig Oocyte Quality Assessment in relation to Different Follicular Size Based on Lab-on-Chip Technology
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Effect of Differentiated Nitrogen Fertilization on the Enzymatic Activity of the Soil for Sweet Potato (Ipomoea batatas L. [Lam.]) Cultivation
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The Effects of Temperature on the Quality and Storage Stalibity of Sweet Potato (Ipomoea batatas L. [Lam]) Grown in Central Europe
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A GIS-based WFD oriented typology of shallow micro-tidal soft bottom using wave exposure and turbidity mapping
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Dual-band Millimetre Wave MIMO Antenna with Reduced Mutual Coupling Based on Optimized Parasitic Structure and Ground Modification
PublicationIn this study, a high-isolation dual-band (28/38 GHz) multiple-input–multiple-output (MIMO) antenna for 5G millimeter-wave applications is presented. The antenna consists of two interconnected patches. The primary patch is connected to the inset feed, while the secondary patch is arc-shaped and positioned over the main patch, opposite to the feed. Both patches function in the lower 28 GHz band, while the primary patch is accountable...
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Wideband High-Gain Low-Profile Series-Fed Antenna Integrated with Optimized Metamaterials for 5G millimeter Wave Applications
PublicationThis 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...
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Modelling of in-plane wave propagation in a plate using spectral element method and Kane–Mindlin theory with application to damage detection
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Modelling of in-plane wave propagation in a plate using spectral element method and Kane-Mindlin theory with application to damage detection
PublicationThis 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...
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Investigations on the influence CuO doping on elastic properties of Li2SO4–MgO–P2O5 glass system by means of acoustic wave propagation
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Influence of NiO doping on elastic properties of Li2SO4-MgO-P2O5 glass system-Investigation by means of acoustic wave propagation
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Plasma diagnostics of low pressure high power impulse magnetron sputtering assisted by electron cyclotron wave resonance plasma
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Corrosion degradation monitoring of ship stiffened plates using guided wave phase velocity and constrained convex optimization method
PublicationThe study presents an experimental investigation on the corrosion degradation level assessment using nondestructive wave-based methods. The degradation level of ship structural elements has been assessed in two different ways. The first one is based on the spectral decomposition and zero-crossing incorporated reconstruction of the dispersion curve approach of the antisymmetric Lamb wave mode and the best matching of the theoretical...
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Design and Characterization of a Planar Structure Wideband Millimeter-Wave Antenna with Wide Beamwidth for Wearable off-body Communication Applications
PublicationThis 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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Damage imaging algorithm for non-destructive inspection of CFRP/steel adhesive joints based on ultrasonic guided wave propagation
PublicationThe paper concerns assessing the quality of the adhesive connection between a steel plate and the reinforcing CFRP laminate. A three-stage algorithm for non-destructive damage imaging was developed. As the first step, an initial study involving dispersion curves of joint components was executed to determine the material parameters and the appropriate excitation frequency. During the second step, damage identification in three-layer...
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Cascading transitions toward unconventional charge density wave states in the quasi-two-dimensional monophosphate tungsten bronze P4W16O56
PublicationSingle 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...
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LAB ANIMAL
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LAB ON A CHIP
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Evaluation of Lower Limb Muscle Electromyographic Activity during 400 m Indoor Sprinting among Elite Female Athletes: A Cross-Sectional Study
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Damage detection in composite truss structure by application of elastic waves.
PublicationW pracy przedstawiono zastosowanie fal sprężystych do detekcji pęknięć zmęczeniowych w konstrukcjach kompozytowych.
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Excitation of Waves in a Dispersive Medium. Example of Flow of a Bubbly Liquid
PublicationThe excitation of wave motion by an external source and the interaction of modes inherent to a ow in a dispersive medium are considered. Dispersion is caused by the presence of gaseous bubbles in a liquid. A large variety of steady excited waveforms is possible when the exciting wave is also steady and propagates at a constant velocity. The velocities of the exciter and forced waves may be dierent. This leads to a variety of non-stationary...
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GUIDED WAVES IN SHIP STRUCTURAL HEALTH MONITORING – A FEASIBILITY STUDY
PublicationShips and offshore structures operate in a severe corrosion degradation environment and face difficulty in providing long- lasting corrosion protection. The Classification Societies recommend regular thickness measurements leading to structural component replacements, to ensure structural integrity during service life. The measurements are usually performed using ultrasonic thickness gauges and such an approach requires multiple...
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Pressure distribution for different types of the finite amplitude waves sources
PublicationPrzedstawiono model matematyczny i przykładowe wyniki badań numerycznych zjawiska oddziaływań fal o skończonej amplitudzie w wodzie. Model matematyczny zbudowano w oparciu o równanie KZK. Zagadnienie różniczkowe rozwiązano stosując metodę różnic skończonych. Rozważono różne rozkłady ciśnienia na źródle kołowym i bez osiowej symetrii.
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Application of guided waves in the evaluation of steel-concrete adhesive connection
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Damage detection strategies based on propagation of guided elastic waves
PublicationW pracy przedstawiono wyniki symulacji numerycznych oraz badań eksperymentalnych nad wykorzystaniemprowadzonych falsprężystych do wykrywania ilokalizacji uszkodzeń w dwu i trójwymiarowych elementach konstrukcyjnych wykonanych z materiałów izotropowych i kompozytowych.
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Universities in a knowledge-based society - their role and challenges they have to face
PublicationW artykule przedstawiono zagadnienia związane z uczelniami wyższymi we współczesnym społeczeństwie opatym na wiedzy. Wciąż zmieniające się środowisko uniwersyteckie wymaga od uczelni szybkiego dostosowywania się do nowych wymagań studentów, ich rodziców, czy pracodawców. W artykule zawarto opis zmian dotyczących popytu na edukację, współpracy między uczelnią i środowiskiem biznesowym, a także internacjonalizacji i globalizacji...
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Universities in a knowledge-based society - their role and challenges they have to face
PublicationArtykuł opisuje rolę instytucji edukacyjnych wraz z problemami i wyzwaniami, którym muszę one sprostać w gospodarce opartej na wiedzy.
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Luminance Distribution Measurements in CAVE-Type Virtual Reality Systems
PublicationIn this article, the immerse 3D visualization lab just opened at the Gdańsk University of Technology is presented. The effect of user “immersion,” it such virtual reality systems, is largely dependent on the optical properties of projected images. Luminance distribution of screens was measured and the luminance uniformity was determined and discussed.
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Standing Waves in a Rectangular Resonator Containing Acoustically Active Gases
PublicationThe distribution of perturbations of pressure and velocity in a rectangular resonator is considered. A resonator contains a gas where thermodynamic processes take place, such as exothermic chemical reaction or excitation of vibrational degrees of a molecule’s freedom. These processes make the gas acoustically active under some conditions. We conclude that the incident and reflected compounds of a sound beam do not interact in the...
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Within- and between-firm wage inequalities and trade integration in GVC
PublicationThis paper examines between- (inter) and within- (intra) firm wage inequality using rich employer-employee data for 12 European countries. We confirm that much overall wage inequality is observed within sectors and within occupations. The share of the within- and between-firm components in overall wage inequality varies across countries. We estimate the link between involvement in global value chains (GVCs) and wages differentiating...
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Review of Selected Methods for Prediction of Added Resistance in Following Waves
PublicationThe added resistance in waves is a mean value of non-linear, second order reaction of a ship to incoming waves. In the beginning of the 20th century, the experimental methods for investigation of ship hydrodynamics at model scale were developed. They allowed the evaluation of added resistance by measurements in irregular waves (directly) or by measurements in regular waves (in-direct method). The main goal was to find more precise...
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Have you heard about ALAN? Now, there is also ROLAN!
PublicationThis article examines the new ROLAN movement and points out why this might be the next big thing for lighting professionals.
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Anti-plane waves in an elastic thin strip with surface energy
PublicationWe consider anti-plane motions of an elastic plate taking into account surface energy within the linear Gurtin–Murdoch surface elasticity. Two boundary-value problems are considered that describe complete shear dynamics of a plate with free faces or with free and clamped faces, respectively. These problems correspond to anti-plane dynamics of an elastic film perfectly or non-perfectly attached to a rigid substrate. Detailed analysis...
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CONTROL OF THE WAVES IN A TOWING TANK WITH THE USE OF A BLACK-BOX MODEL
PublicationThe paper describes an adaptive control system of the waves, implemented in the Ship Design and Research Centre, CTO S.A. The purpose of generating the waves in the towing tank is the modelling of the environmental conditions during hydrodynamic model tests. The tests are performed on scale models of towed or free running ships, anchored structures like oil rigs or bottommounted structures, e.g. wind turbines. In the towing tank...
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Modeling of luminance distribution in CAVE-type virtual reality systems
PublicationAt present, one of the most advanced virtual reality systems are CAVE-type (Cave Automatic Virtual Environment) installations. Such systems are usually consisted of four, five or six projection screens and in case of six screens arranged in form of a cube. Providing the user with a high level of immersion feeling in such systems is largely dependent of optical properties of the system. The modeling of physical phenomena plays nowadays...
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Damage detection in a bolted lap joint using guided waves
PublicationThe paper presents the experimental investigation of guided waves application to the condition assessment of prestressed bolted connections and a concept of new quantitative indicator. The main goal of the research was the analysis of the influence of the contact conditions changes to the characteristics of a propagating disturbance. The experimental tests were carried out for a single bolted lap joint. The excitation and acquisition...
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Application of guided waves in the evaluation of steel-concrete adhesive connection
PublicationThe aim of the paper is the application of guided waves in the evaluation of a condition state of adhesive connection between steel and concrete. The study concerns a push-out specimen consisting of two steel plates glued to opposite faces of a concrete cube with the use of structural adhesive. Wave propagation in the specimen without external load is investigated both experimentally and numerically. The second stage of the investigation...
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Calculation methods of interaction of electromagnetic waves with objects of complex geometries
PublicationModeling of the electromagnetic interaction with different homogeneous or inhomo-geneous objects is a fundamental and important problem. It is relatively easy to solve Maxwellequations analytically when the scattering object is spherical or cylindrical, for example. How-ever, when it loses these properties all that is left for us is to useapproximation models, to ac-quire the solution we need. Modeling of complex, non-spherical,...
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Combining of global and local stresses in ship hulls on ocean waves.
PublicationOpisano zagadnienia superpozycji naprężeń dynamicznych od zginania ogólnego i strefowego, we wzdłużnych wiązarach kadłuba statku. Krytycznie skomentowano wymagania przepisów klasyfikacji i budowy statków, dotyczące oceny wytrzymałości tych elementów konstrukcji. Przedstawiono sposób wykonywania prognozy długoterminowej naprężeń w tych elementach i zaproponowano sposób sumowania charakterystycznych wartości naprężeń od zginania...
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Wave energy attenuation in fields of colliding ice floes – Part 2: A laboratory case study
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Highly Integrable Planar-structured Printed Circularly Polarized Antenna for Emerging Wideband Internet of Things Applications in the Millimeter-Wave Band
PublicationThis paper proposes a numerically and experimentally validated printed wideband antenna with a planar geometry for Internet of Things (IoT) applications. This design tackles the challenges associated with deploying IoT sensors in remote areas or across extensive geographical regions. The proposed design exploits a coplanar-waveguide-fed modified microstrip line monopole for excitation of circularly polarized waves radiating in...
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Wytwarzanie harmonicznych w zależności od rozkładu ciśnienia fali pierwotnej = Dependence of harmonic generation on primary wave pressure distribution
PublicationRozważano zagadnienie wytwarzania składowych harmonicznych podczas rozchodzenia się w wodzie fal promieniowanych przez źródła kołowe o różnych rozkładach ciśnienia. Model matematyczny zbudowano w oparciu o równanie KZK. Do rozwiązania problemu zastosowano metodę bilansu harmonicznych. Analizowano zmiany składowych harmonicznych ciśnienia w obrębie wiązki akustycznej.
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The spectral finite element model for analysis of flexural-shear coupled wave propagation. Part 2: Delaminated multilayer composite beam
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