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Search results for: WAVE CELERITY
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The spectral finite element model for analysis of flexural–shear coupled wave propagation
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Slow-wave resonant structures in branch-line coupler miniaturization: a case study
PublicationA case study of novel slow-wave resonant structures dedicated to efficient microstrip branch-line coupler size reduction has been presented. A compact 3-dB branch-line coupler has been designed to mimic the performance of its conventional counterpart, simultaneously demonstrating a substantial 88% surface area reduction. The vital usefulness of the approach in the process of microstrip line abbreviation has been experimentally...
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Damage detection of a T-shaped panel by wave propagation analysis in the plane stress
PublicationW pracy zaprezentowano podejście obliczeniowe do analizy propagacji fal w płaskim stanie naprężenia. Problem brzegowo-początkowy podlega przestrzennej aproksymacji z użyciem wielowęzłowych, izoparametrycznych, czworobocznych elementów klasy C0. Macierze elementowe są całkowane numerycznie za pomocą kwadratury Gauss-Legendre-Lobatto. Aproksymację w dziedzinie czasu wykonano za pomocą algorytmu Newmarka. Symulacje numeryczne przeprowadzono...
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Assessment of flexural beam behaviour theories used for dynamics and wave propagation problems
PublicationW pracy przedstawiono i porównano teorie belek zginanych począwszych od teorii elementarnych, aż do teorii wyższych rzędów. Przedstawiono krzywe dyspersi dla poszczególnych teorii i na ich podstawione oszacowano zakres stosowalności danej teorii.
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Pulse wave velocity is associated with early clinical outcome after ischemic stroke
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Fibrinogen and d-dimer in contrasting relation with measures of wave reflection and arterial stiffness
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Pulse wave velocity to the global longitudinal strain ratio in survivors of myocardial infarction
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Acousto-optic interaction of a Gaussian laser beam with an ultrasonic wave of cylindrical symmetry
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DETECTION OF DEBONDING IN STEEL BARS EMBEDDED IN CONCRETE USING GUIDED WAVE PROPAGATION
PublicationThe paper presents a non-destructive diagnostic technique based on guided wave propagation phenomenon used to assess the adhesive bonding between a steel bar and a concrete cover. Double-layered cylindrical specimens with different levels of debonding and its location were investigated. The influence of bonding length on the excitation of multiple modes of longitudinal guided waves was analysed. Numerical simulations of guided...
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Measurement and Analysis of the Radio Wave Polarisation in Off-Body Communications in Indoor Environment
PublicationThe paper describes an analysis of the radio wave polarisation in off-body communications in indoor environment. The measurement stand for polarisation measurements has been shortly described. Five investigated scenarios with different body postures and different antenna placements have been characterize. The vertical and horizontal components of received radio signal have been analysed. The measure used in analysis is a ratio...
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Edge-Guided Mode Performance and Applications in Nonreciprocal Millimeter-Wave Gyroelectric Components
PublicationThe analogies between the behavior of gyromagnetic and gyroelectric nonreciprocal structures, the use of the simple transfer matrix approach, and the edge-guided (EG) wave property, supported in a parallel plate model for integrated magnetized semiconductor waveguide, are investigated in those frequency regions, where the effective permittivity is negative or positive. As with their ferrite counterparts, the leakage of the EG waves...
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MEASUREMENT AND ANALYSIS OF A FLOOD WAVE PROPAGATION ON THE KACZA RIVER IN GDYNIA IN NORTHERN POLAND
PublicationKacza river is located in northern Poland in the neighborhood of the Gulf of Gdansk and the Baltic Sea. A Kacza having length of 15 km and catchment area of 53 km2 collects the water into the Gulf mostly from inhabited and forested areas within the administrative boundaries of the city of Gdynia. On the 14th and 15th of July 2016 in northern Poland on the large area of Tri-City agglomeration (Gdynia, Gdansk and Sopot) total daily...
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Continuous wave sonar with hyperbolic frequency modulation keyed by pseudo-random sequence
PublicationA CW FM type sounding signal is used in the classical solution of silent sonar. While the signal provides a relatively simple implementation of digital signal processing, and ensures good detection conditions, unfortunately, in the presence of the Doppler effect, distance measurement results tend to be wrong. This is due to the fact that the received signal’s instantaneous frequency value is dependent both on the distance to the...
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Application of Pierson-Moskowitz wave spectrum to solution differential equations of multihull vessel
PublicationMotion of a dynamic system can be generated by different external or internal factors. At mathematical modelling external excitation factors of the most significant effect on the system, are selected. Such external factors are usually called excitations. Response of the system to given excitations is mathematically characterized by a definite transformation called operator of a system. For a broad class of dynamic systems the...
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Excitation of Non-Wave Modes by Sound of Arbitrary Frequency in a Chemically Reacting Gas
PublicationThe nonlinear phenomena in the field of high intensity sound propagating in a gas with a chemical reaction, are considered. A chemical reaction of A → B type is followed by dispersion and attenuation of sound which may be atypical during irreversible thermodynamic processes under some conditions. The first and second order derivatives of heat produced in the chemical reaction evaluated at the equilibrium temperature, density and...
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Spectral Methods for Modelling of Wave Propagation in Structures in Terms of Damage Detection—A Review
PublicationModern methods of detection and identification of structural damage direct the activities of scientific groups towards the improvement of diagnostic methods using for example the phenomenon of mechanical wave propagation. Damage detection methods that use mechanical wave propagation in structural components are extremely effective. Many different numerical approaches are used to model this phenomenon, but, due to their universal...
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Design and Optimization of Metamaterial-Based 5G Millimeter Wave Antenna for Gain Enhancement
PublicationIn this brief, a low profile, broadband, high-gain antenna array based on optimized metamaterials (MMs) with dual-beam radiation is reported for 5G millimeters wave (mm-wave) applications. The design is a simple bow tie operating at a 5G band of 28 GHz. It consists of two bow ties with substrate integrated waveguide (SIW)-based power splitter. A broad impedance bandwidth of 26.3−29.8 GHz is obtained by appropriately combining the...
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Simple 60 GHz Switched Beam Antenna for 5G Millimeter-Wave Applications
PublicationA new 60 GHz band single-input switched beam antenna is proposed for the fifth-generation (5G) millimeter-wave network applications. The presented design is capable of electronically switching the main beam in two different directions via a proposed microstrip-line-to-slotline single-pole dual-throw (SPDT) switch based on commercially available p-i-n diodes. The antenna is fabricated in a low-cost printed circuit board process...
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Design of an Autonomous IoT Node Powered by a Perovskite-Based Wave Energy Converter
PublicationThis 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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Nondestructive corrosion degradation assessment based on asymmetry of guided wave propagation field
PublicationThe article presents the results of numerical and experimental investigation of guided wave propagation in steel plates subjected to corrosion degradation. The development of novel procedures allowing for the assessment of the corrosion degradation level is crucial in the effective diagnostics of offshore and ship structures that are especially subjected to aggressive environments. The study’s main aim is to investigate the influence...
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5G Millimeter Wave Network Optimization: Dual Connectivity and Power Allocation Strategy
PublicationThe 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...
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Investigating Fuel Injection Strategies to Enhance Ship Energy Efficiency in Wave Conditions
PublicationThe prediction of fuel consumption and resulting transportation costs is a crucial stage in ship design, particularly for conditions involving motion in waves. This study investigates the real-time fuel consumption of a container ship when sailing in waves. The overall ship performance is evaluated using a novel non-linear coupled hull-engine-propeller interaction model. A series of towing tank experiments for hull resistance in...
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60 GHz Microstrip Van Atta Arrays for Millimeter Wave Identification and Localization
PublicationIn this paper performance comparison of co-polarized and cross-polarized microstrip Van Atta arrays working in the 60 GHz frequency range is presented. They can be treated as simple chipless RFID tags with frequency response based identification. Tags with three different nominal resonance frequencies of 57, 62 and 67 GHz are designed by scaling optimized base model. Designed 62 GHz co-polarized and cross-polarized arrays with...
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Baseline-free debonding detection in reinforced concrete structures by elastic wave propagation
PublicationThe article presents the results of the numerical and experimental analysis concerning wave propagation in reinforced concrete (RC) beams with various extent of debonding between the steel rod and concrete cover. The main aim of the paper was to consider the unsolved research gaps, which considerably limit the application of wave-based methods in practice. The propagation of the flexural wave modes excited and registered on the...
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Ultrafast Intramolecular Relaxation and Wave-Packet Motion in a Ruthenium-Based Supramolecular Photocatalyst
PublicationThe hydrogen-evolving photocatalyst [(tbbpy)2 Ru(tpphz)Pd(Cl)2 ](2+) (tbbpy=4,4'-di-tert-butyl-2,2'-bipyridine, tpphz=tetrapyrido[3,2-a:2',3'-c:3'',2''-h:2''',3'''-j]phenazine) shows excitation-wavelength-dependent catalytic activity, which has been correlated to the localization of the initial excitation within the coordination sphere. In this contribution the excitation-wavelength dependence of the early excited-state relaxation...
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Design of quarter-wave compact impedance transformers using coupled transmission lines
PublicationPrzedstawiono porównanie wyników symulacji jedno i wielosekcyjnych transformatorów impedancji budowanych w postaci struktur wykorzystujących idealnenie sprzężone linie transmisyjne, idealne sprzężone symetryczne linie transmisyjne oraz rzeczywiste sprzężone linie mikropaskowe. Pokazano, że możliwa jest konstrukcja transformatorów impedancji o bardzo dobrych parametrach technicznych wykorzystująca sprzężone linie mikropaskowe, pomimo...
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Impact of sea wave stochastic characteristics on ship propulsion control system design.
PublicationWybrano do rozważań (symulacji komputerowej) 8 rejonów morskich w 4 porach roku. Określono w nich gęstość widmową amplitudy fali morskiej. Założono, upraszczająco, regulator typu PID. Dla wybranego typu statku wykonane badania symulacyjne odnoszą się do wybranych rejonów mórz i pór roku. Okazuje się, że dobierając zarówno współczynnik wzmocnienia regulatora jak i stałą całkowania, można minimalizować wartości wariancji, na przykład,...
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Piecewise continuous distribution function method in the theory of wave disturbances of inhomogeneous gas
PublicationUkład równań typu hydrodynamicznego dla warstwowych gazów w polu grawitacyjnym pochodzi od równania BGK metodą częściowej ciągłej funkcji dystrybucji. Otrzymany system równań uogólnia układ Naviera-Stokesa w dowolnych liczbach Knudsena.
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Simplified Numerical Model for Transient Flow of Slurries at Low Concentration
PublicationRapid transients are particularly dangerous in industrial hydro-transport systems, where solid-liquid mixtures are transported via long pressure pipelines. A mathematical description of such flow is difficult due to the complexity of phenomena and difficulties in determining parameters. The main aim of the study was to examine the influence of the simplified mixture density and wave celerity description on satisfactory reproduction...
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Wage determination, Global Value Chains and role played by wage bargaining schemes: The case of Poland
PublicationThis study examines the linkages between GVC involvement and wages in Poland given different wage bargaining schemes. The analysis is based on microdata from the European Structure of Earnings Survey for Poland combined with sectoral data from the World Input-Output Database. In particular, two measures of GVC involvement were used: the share of foreign value added (FVA) to export and the measure of traditional offshoring. The...
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Numerical Analysis of the Unsteady Propeller Performance in the Ship Wake Modified by Different Wake Improvement Devices
PublicationThe paper presents summary of numerical analysis of the unsteady propeller forces and induced pressure pulses generated by the selected real propeller of 7000 tons product tanker, operating in five different wakefields including four inflenced by the different wake improvement devices. The results of the analysis are partly compared with experimental data and univocal conclusions about the optimum wake improvement device are presented.
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Capra. The journal for Cave Archaeology and Palaeontology
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INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES
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Journal of Infrared Millimeter and Terahertz Waves
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Methylation of Estrogen Receptor 1 Gene in the Paraspinal Muscles of Girls with Idiopathic Scoliosis and Its Association with Disease Severity
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Association of LBX1 Gene Methylation Level with Disease Severity in Patients with Idiopathic Scoliosis: Study on Deep Paravertebral Muscles
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Nuclear Magnetic Relaxation and d-Wave Pairing in a Model of a Superconductor with Non-Retarded Attraction
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Nuclear magnetic relaxation and d-wave pairing in an extended Hubbard model with diagonal disorder
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Lamb wave based structural damage detection using cointegration and fractal signal processing
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Cointegration and wavelet-analysis-based approach for Lamb-wave-based structural damage detection
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Electrochemical sensor for measurement of volatile organic compounds employing square wave perturbation voltage
PublicationThe paper presents the results of investigation on a prototype sensor for measurement of benzaldehyde in air. Sensitivity and limit of quantification of the sensor were determined for different internal electrolyte using the square wave voltammetry (SWV) as a detection technique. The working and counter electrodes were made of platinum. Ionic liquids 1-hexyl, 3-methylimidazolium chloride,1-hexyl, 3-methylimidazolium bis (trifluoromethanesulfonyl)...
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Certain numerical issues of wave propagation modelling in rods by the Spectral Finite Element Method
PublicationW pracy omówiony zagadnienia związane z modelowaniem propagacji fal sprężystych metodą Spektralnych Elementów Skończonych. Przedstawiono wpływ postaci macierzy mas na błędy rozwiązania. Omówiono zakres stosowalności modeli.
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MicroscopicA75sNMR study of the effect of impurities on the first-order spin-density-wave transition inBaFe2As2
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Piecewise continuous distribution function method: Fluid equations and wave disturbances at stratified gas
PublicationUkład równań typu hydrodynamicznego dla warstwowych gazów w polu grawitacyjnym pochodzi od równania BGK metodą częściowej ciągłej funkcji dystrybucji. Otrzymany system równań uogólnia układ Naviera-Stokesa w dowolnych liczbach Knudsena. Rozwiązania WBK dla ultradźwięku wprowadza się w przypadku stratyfikacji exponecjalnej.
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Modelling of wave propagation in composite plates using the time domain spectral element method
PublicationW pracy przedstawiono wyniki obliczeń propagacji fali sprężystej w płycie kompozytowej modelowanej z wykorzystaniem czasowego sformułowania metody elementów spektralnych
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Analysis of electromagnetic plane wave scattering from 2-d periodic arrangements of posts
PublicationArtykuł prezentuje metodę analizy rozpraszania fali elektromagnetycznej od układu periodycznie rozłożonych obiektów cylindrycznych na płaszczyźnie. Opisywane podejście analizy wykorzystuje pełnofalowe rozwiązanie oparte na metodzie dopasowania rodzajów. Wynikiem analizy jest wielorodzajowa macierz rozproszenia badanych powierzchni periodycznych.
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Arterial stiffness, central hemodynamics and wave reflection in normal pregnancy and control nonpregnant women
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Experimental and numerical study on damage detection in an L-joint using guided wave propagation
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Experimental and numerical study on damage detection in an L-joint using guided wave propagation
PublicationW pracy zaprezentowano metodę wykrywania i lokalizacji uszkodzeń w konstrukcji ramowej za pomocą podłużnych i poprzecznych fal sprężystych. Przeprowadzono badania numerczyne i eksperymentalne na modelu bez uszkodzenia oraz na modelu z wsprowadzonym nacięciem. Do modelowania zastosowano metodę elementów spektralnych. W pracy przedstawiono sformułowanie nowego element spektralnego dla ram płaskich bazującego na teorii pręta Mindlina...
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Initial Investigation of Wave Interactions During Simultaneous Valve Closures in Hydraulic Piping Systems
PublicationThe effects of interference of pressure waves in simple piping systems were studied. A freeware computer code Allievi developed at the University of Valencia was used to simulate dynamic waveforms in simple and complex networks. The tests were carried out according to three scenarios. No pressure increases significantly exceeding the Joukowsky pressure in simple cases were noticed. When the effects of the simultaneous closing of...