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Search results for: UWA CHANNEL
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Cechy budownictwa w roku 2025 - spojrzenie z USA
PublicationOmówiono oczekiwany rozwój budownictwa w świecie do r. 2025, widziany z perspektywy USA.
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Kilka uwag o misjach i strategiach uczelni technicznych
PublicationW artykule przedstawiono poglądy wybranych badaczy szkolnictwa wyższego na temat wyzwań stojących przed współczesnymi szkołami wyższymi.Opierając się na pracy de Wita i Meyera, wskazano wybrane napięcia strategiczne w obszarze tworzenia strategii na uczelniach oraz pokazano możliwości zarządzania nimi. W dalszej części scharakteryzowano misje i strategie kilku wybranych uczelni technicznych.W podsumowaniu stwierdzono,że misje...
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On the approximation of the UWB dipole elliptical arms with stepped-edge polygon
PublicationA simple method of approximation of the ellipticalpatch with stepped-edge polygon is proposed as an introductionto wider studies over the planar ultrawideband (UWB) antennas.The general idea is to replace the elliptical patch with an equivalentpolygonal patch, with minimum loss in the performance. Theprinciples of the proposed method are presented in this letter, aswell as the results of performed numerical studies and its experimentalverification....
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Unified design procedure for planar dipoles oriented on uwb application
PublicationW pracy zaproponowaną ujednoliconą metodę projektowania dipoli planarnych dla zastosowań UWB. Prowadzi ona do uzyskania dobrych wyników dopasowania impedancji w paśmie UWB. Zagadnienie projektowania zostało podzielone na dwie części: projekt radiatora (dla którego określono współczynnik jakości - Radiator Quality Factor) oraz projekt symetryzatora. W oparciu o zaproponowany algorytm zaprojektowano i zrealizowano dwie anteny charakteryzujące...
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Efficiency of IEEE 802.15.4a UWB Impulse Radio Spectrum Shaping
PublicationThis paper presents results of impulse radio signal spectrum shaping efficiency investigations. Basic parameters of IEEE 802.15.4a UWB signal and outline of proposed spectrum shaping methods are briefly described. The main part of the paper presents influence of signal and algorithms parameters on the results of spectrum shaping.
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Concept of Compatibility Region for the Evaluation of IR UWB Electromagnetic Compatibility
PublicationThis paper presents a new proposal for the unified evaluation of ultra wideband and narrowband radio communication systems electromagnetic compatibility, called “compatibility region”. The idea of compatibility region is based on the relation between the ratio of narrowband to ultra wideband signal power in a receiver and some transmission quality indicators (bit error rate, effective data rate).
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A Concept and Design Optimization of Compact Planar UWB Monopole Antenna
PublicationA novel structure concept of a compact UWB monopole antenna is introduced together with a low-cost design optimization procedure. Reduced footprint is achieved by introduction of a protruded ground plane for current path increase and a matching transformer to ensure wideband impedance matching. All geometrical parameters of the structure are optimized simultaneously by means of surrogate based optimization involving variable-fidelity...
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Multi-objective optimization for assessment of topological modification in UWB antennas
PublicationThis paper addresses an issue of systematic and rigorous assessment of effects of topological modifications on the performance of compact UWB antennas. Application of fast surrogate-assisted multi-objective optimization procedures allows us for obtaining, in a practically acceptable timeframe, a set of designs representing the best possible trade-offs between conflicting objectives (here, antenna size minimization and reduction...
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Design and Optimization of a Compact Planar Radiator for UWB Applications and Beyond
PublicationA compact monopole antenna for ultra-wideband (UWB) and beyond applications has been proposed. The radiator is based on the monopole topology. The super-wideband behavior has been achieved using a combination of spline-based modifications applied to the driven element, as well as utilization of a tapered feed and a slot-modified ground plane. The electrical performance of the structure has been tuned using a numerical optimization...
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Uptake, tissue distribution, and metabolism of malachite green in the channel catfish (Ictalurus punctatus)
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Integration of multi-interface conversion channel using FPGA for modular photonic network
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System identification theory-based estimation of underwater acoustic channel for broadband communications.
PublicationPłytki kanał podwodny jest niestacjonarny z powodu wielokrotnych odbić fal dźwiękowych od powierzchni wody oraz ruchu nadajnika i odbiornika systemu komunikacyjnego. Dla zapewnienia szybkiej transmisji danych niezbędna jest estymacja kanału oparta na equalizacji adaptacyjnej. W systemach komunikacji podwodnej stosowane są zazwyczaj equalizery DFE z zaimplementowanymi algorytmami najmniejszych kwadratów: LMS oraz RLS.W artykule...
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Performance analysis of standard and modified EY-NPMA channel access algo-rithms
PublicationPodczas minionego 10-ciolecia notuje się szybki rozwój lokalnych sieci bezprzewodowych (WLANy). Proponowane rozwiązania dotyczą zarówno sieci opartych o przesył komórek (zgodnych z ATM), jak i sieci pakietowych (zgodnych z E-thernetem). Po rozważeniu drugiego z wymienionych typów sieci, wydaje się dzisiaj, iż pakietowe WLANy będą oparte głównie na dwóch standardach, mianowicie: IEEE 802.11 [6]) - wykorzystującym protokół dostępu...
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Experimental Study of the Influence of Small Upward Seepage on Open-Channel Flow Turbulence
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Numerical Simulations of DDT Limits in Hydrogen-Air Mixtures in Obstacle Laden Channel
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Adaptive Identification of Underwater Acoustic Channel with a Mix of Static and Time-Varying Parameters
PublicationWe consider the problem of identification of communication channels with a mix of static and time-varying parameters. Such scenarios are typical, among others, in underwater acoustics. In this paper, we further develop adaptive algorithms built on the local basis function (LBF) principle resulting in excellent performance when identifying time-varying systems. The main drawback of an LBF algorithm is its high complexity. The subsequently...
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Comparison of Doppler Effect Estimation Methods for MFSK Transmission in Multipath Hydroacoustic Channel
PublicationUnderwater wireless communication remains a challenging topic, particularly for applications such as wreck penetration where multipath and Doppler effects are very intense. These effects are becoming even more difficult to mitigate for fast data transmission systems that utilize wideband signals. Due to the low propagation speed of acoustic wave in the water, there is a significant difference between the Doppler shift for lower...
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Selected local stability problems of channel section flanges made of aluminium alloys
PublicationThe paper addresses the issue of local buckling of compressed flanges of cold-formed thin-walled channel columns and beams with nonstandard flanges composed of aluminium alloys. The material behaviour follows the Ramberg–Osgood law. It should be noted that the proposed solution may be also applied for other materials, for example: stainless steel, carbon steel. The paper is motivated by an increasing interest in nonstandard cold-formed...
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Effects of subfilter velocity modelling on dispersed phase in LES of heated channel flow
PublicationA non-isothermal turbulent flow with the dispersed phase is modelled using the Large Eddy Simulation (LES) approach for fluid, one-way coupled with the equations of point-particle evolution. The channel is heated at both walls and isoflux boundary conditions are applied for fluid. Particle velocity and thermal statistics are computed. Of particular interest are the r.m.s. profiles and the probability density function of particle...
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ADAPTIVE IDENTIFICATION OF TIME-VARYING IMPULSE RESPONSE OF UNDERWATER ACOUSTIC COMMUNICATION CHANNEL
PublicationThe transmission properties of underwater acoustic communication channel can change dynamically due to the movement of acoustic system transmitter and receiver or underwater objects reflecting transmitted signal. The time-varying impulse response measurement and estimation are necessary to match the physical layer of data transmission to instantaneous channel propagation conditions. Using the correlative measurement method, impulse...
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Radio Channel Measurements in 868 MHz Off-Body Communications in a Ferry Environment
PublicationIn this paper, a characterization of the 868 MHz off-body radio channel in BANs is presented. Measurements were carried out in a ferry environment using a specific set-up. A method for path loss using radio distance measurements (RDMs) was developed. It allows to automate the measurements process and make it independent from the variable speed of a moving person. Based on the observed path loss as a function of distance, the obtained...
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Tracking body movement for radio channel measurements in BAN with indoor positioning system
PublicationThis paper presents indoor positioning system based on inertial navigation with additional distance measurements using UWB modems and map matching to increase accuracy and eliminate position drift. Such system may be used to track position of human body during radio channel measurements for body area networks. Performance of proposed system and limitations caused by inertial navigation are briefly described.
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Local buckling of thin-walled channel member flange made of aluminum alloy
PublicationThe 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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ECHOES REDUCTION DURING DIGITAL DATA TRANSMISSION IN HYDROACOUSTIC CHANNEL – LABORATORY EXPERIMENT
PublicationThe possibility of using a hydroacoustic channel for digital data transmission is very limited. This is due to the effect of multipath propagation of the emitted acoustic wave and the damping of the mechanical wave in this medium, which increase with frequency. The first of these phenomena results in inter-symbol interference disturbances in data transmission systems, including even hundreds of symbols. Due to the number of reflections...
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Numerical Analysis of Turbulent Flow over a Backward-facing Step in an Open Channel
PublicationComputational examinations of the flow field in an open channel having a single Backward--Facing Step (BFS) with a constant water depth of 1.5 m were performed. The effects of the expansion ratio, and the flow velocity along the reattachment length, were investigated by employing two different expansion ratios of 1.5 and 2, and eight various flow velocities of 0.5, 1, 2, 3, 4, 5, 7.5 and 10 m/sec in the Computational Fluid Dynamic...
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Channel State Estimation in LTE-Based Heterogenous Networks Using Deep Learning
PublicationFollowing the continuous development of the information technology, the concept of dense urban networks has evolved as well. The powerful tools, like machine learning, break new ground in smart network and interface design. In this paper the concept of using deep learning for estimating the radio channel parameters of the LTE (Long Term Evolution) radio interface is presented. It was proved that the deep learning approach provides...
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A Method for Underwater Wireless Data Transmission in a Hydroacoustic Channel under NLOS Conditions
PublicationWireless data transmission in the hydroacoustic channel under non-line-of-sight (NLOS) propagation conditions, for example, during a wreck penetration, is difficult to implement reliably. This is mostly due to the multipath propagation, which causes a reduction in the quality of data reception. Therefore, in this work an attempt has been made to develop a reliable method of wireless underwater communication test it under the NLOS...
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A Wideband Channel Model for Body Area Networks in Circular Metallic Indoor Environments
PublicationIn this paper, the wideband characterization of the propagation channel in circular metallic indoor environments is addressed, regarding Body Area Networks and 5G small cells, an analytical model for the dependence of the mean delay and the average delay spread on the circle radius, the working frequency and the distance between the transmitter and the receiver being proposed. The derivation of the model is initially done analytically,...
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Application of Diversity Combining with RLS Adaptive Filtering in Data Transmission in a Hydroacoustic Channel
PublicationWhen transmitting data in a hydroacoustic channel under difficult propagation conditions, one of the problems is intersymbol interference (ISI) caused mainly by the effect of multipath propagation. This phenomenon leads to a decrease in transmission parameters, and sometimes completely prevents it. Therefore, we have made an attempt to use diversity combining with Recursive Least Squares (RLS) adaptive filtering to improve the...
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Capturing nonexponential dynamics in the presence of two decay channels
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Experimental investigations on condensation in flow in small diameter channels
PublicationW pracy przedstawiono innowacyjne podejście do eksperymentalnych badań kondensacji w przepływie oraz omówiono wstępne wyniki badań eksperymentalnych kondensacji etanolu w pionowej rurce srebrnej o średnicy wewnętrznej 2.3 mm.
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Ultrawideband transmission in physical channels: a broadband interference view
PublicationThe superposition of multipath components (MPC) of an emitted wave, formed by reflections from limiting surfaces and obstacles in the propagation area, strongly affects communication signals. In the case of modern wideband systems, the effect should be seen as a broadband counterpart of classical interference which is the cause of fading in narrowband systems. This paper shows that in wideband communications, the time- and frequency-domain...
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Decoherence-free communication over multiaccess quantum channels
PublicationIn this paper we consider decoherence-free communication over multiple access and k-user quantum channels. First, we concentrate on a hermitian unitary noise model U for a two-access bi-unitary channel and show that in this case a decoherence-free code exists if the space of Schmidt matrices of an eigensubspace of U exhibits certain properties of decomposability. Then, we show that our technique is also applicable for generic random unitary...
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Underwater Acoustic Communications in Time-Varying Dispersive Channels
PublicationUnderwater acoustic communication (UAC) system designers tend to transmit as much information as possible, per unit of time, at as low as possible error rate. However, the bit rate achieved in UAC systems is much lower than for wire or radio-communication systems. This is due to disadvantageous properties of the UAC channels, namely the sea and inland waters. Estimation of UAC channel transmission properties is possible within...
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Dwa lata członkostwa krajów Grupy Wyszehradzkiej w Unii Europejskiej
PublicationCelem niniejszego artykułu jest zaprezentowanie wybranych wskaźników makroekonomicznych krajów grupy wyszehradzkiej i ocena zmian jakie nastąpiły w okresie dwóch lat członkostwa Polski, Czech, Słowacji i Węgier w strukturach UE.
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Field investigation and numerical analysis of an inverted pavement system in Tennessee, USA
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Projektowanie ideału, czyli kilka uwag o strategii szkolnictwa wyższego
PublicationW artykule pokazano możliwość opracowania strategii uczelni przy wykorzystaniu metody projektowania ideału opisanej przez R. Ackoffa, J. Magidsona i H. Addisona
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Narrowband Transmission Quality in Presence of Modified IEEE 802.15.4a UWB Signal
PublicationThis paper presents results of measurement of narrowband transmission quality in presence of impulse radio UWB interference. In the first part of paper, unmodified IEEE 802.15.4a IR UWB signal is used. Then some modification of transmitted pulse sequence is proposed, which allow to reduce UWB power spectral density at frequency of narrowbandtransmission. Finally narrowband transmission quality in presence of modified ultrawideband...
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New method of IEEE 802.15.4a UWB Impulse Radio Spectrum Shaping
PublicationThis paper presents a new technique of IEEE 802.15.4a ultra-wideband signal spectrum control, based on changes in sequences of transmitted pulses with very short duration time. Basic parameters of UWB signal and outline of proposed spectrum shaping methods are briefly described. The main part of the paper presents influence of signal and algorithms parameters on the results of spectrum shaping.
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Narrowband Transmission Quality in Presence of Modified IEEE 802.15.4a UWB Signal
PublicationThis paper presents results of measurement of narrowband transmission quality in presence of impulse radio UWB interference. In the first part of paper, unmodified IEEE 802.15.4a IR UWB signal is used. Then some modification of transmitted pulse sequence is proposed, which allow to reduce UWB power spectral density at frequency of narrowband transmission. Finally narrowband transmission quality in presence of modified ultrawideband...
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Narrowband Transmission Quality in Presence of Modified IEEE 802.15.4a UWB Signal
PublicationPublikacja przedstawia opis stanowiska laboratoryjnego użytego do badania wpływu zakłóceń impulsowych na jakość odbioru sygnałów wąskopasmowych. Przedstawione zostały przykładowe wyniki pomiaru jakości transmisji wąskopasmowych wraz z wykazaniem, że modyfikacja widma zakłócającego sygnału IR UWB powoduje poprawę jakości odbioru sygnałów wąskopasmowych.
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Morskie urządzenia odbojowe : Kilka uwag o projektowaniu. Część I
PublicationUrządzenia odbojowe stosowane w budownictwie morskim. Wyszczególnienie aspektów projektowych i krótki przegląd nowych generacji statków (kontenerowców, wycieczkowców i szybkich promów o kadłubie katamarana). Zwrócenie uwagi na ich cechy, jak: kształt wielkość (masa, bezwładność) oraz napęd (manewrowość), istotne z punktu widzenia projektowania i doboru odpowiednich urządzeń odbojowych.
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Novel Structure and EM-Driven Design of Small UWB Monopole Antenna
PublicationA novel structure of a small UWB monopole antenna is presented. In our approach, a compact size is achieved by means of a meander line for current path enlargement as well as the two parameterized slits that introduce additional degrees of freedom helping to ensure good impedance matching. The antenna design is carried out using surrogate-based optimization involving variable-fidelity EM simulations. This allows us to simultaneously...
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Kilka uwag o doskonaleniu zarządzania uczelnią publiczną (artykuł dyskusyjny)
PublicationW artykule zaproponowano adaptację koncepcji organizacji oburęcznej w uczelni publicznej. Istotą jest propozycja zmiany organizacji uczelni o „90o”, tj. z takiej, w której wydziały tworzą oś organizacyjną, a zespoły projektowe oś koordynacyjną do takiej, w której role te są zamienione. Wydziały zajmują się głównie masowym kształceniem studentów na I stopniu studiów, a zespoły kształcą elity studentów II i III stopnia studiów, prowadząc...
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A structure and simulation-driven design of compact CPW-fed UWB antenna
PublicationIn this letter, a structure of a miniaturized ultra-wideband CPW-fed antenna and its design proce-dure are presented. The antenna is a modified version of the design previously proposed in the literature, with additional degrees of freedom introduced in order to improve the structure flexibility. The small size is achieved by executing a rigorous optimization procedure that consists of two stages: (i) smart random search carried...
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Fast simulation-driven design optimization of UWB band-notch antennas
PublicationIn this letter, a simple yet reliable and automated methodology for rapid design optimization of ultra-wideband (UWB) band-notch antennas is presented. Our approach is a two-stage procedure with the first stage focused on the design of the antenna itself, and the secondstage aiming at identification of the appropriate dimensions of the resonator with the purpose of allocating the band-notch in the desired frequency range. For the...
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Trade in value added of countries involved in TTIP: EU-USA comparison
PublicationThe aim of this paper is to present key facts concerning trade in the value added of those countries participating in the Transatlantic Trade and Investment Partnership (TTIP). In particular, we describe how involvement in global production networks (GPN) varies across EU countries with respect to the United States.
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JAKOŚ(Ć) ? : Dwa lata Regionalnej Biblioteki Nanotechnologii Politechniki Gdańskiej
PublicationArtykuł, na przykładzie Regionalnej Biblioteki Nanotechnologii, opisuje w jaki sposób biblioteka jako organizacja radzi sobie w obliczu ciągłych zmian. Przedstawienie RBN oraz umieszczenie jej w otoczeniu zewnętrznym (bliższym i dalszym) i wewnętrznym pokazuje, że dzisiejsze biblioteki muszą wciąż dostosowywać się do zmian. Artykuł stawia również pytanie - jak społeczeństwo wiedzy (jako nowy typ społeczeństwa) ma tą wiedzą zarządzać?...
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Dwa prestiżowe stanowiska dr Anny Wałek, dyrektor Biblioteki PG
PublicationArtykuł prezentuje sukcesy zawodowe dr Anny Wałek, Dyrektor Biblioteki Politechniki Gdańskiej, która w 2021 r. została wybrana na Prezydenta International Association of University Libraries (od stycznia 2022 r.) oraz Przewodniczącą Rady Dyrektorów Polskiej Grupy Użytkowników systemu VIRTUA (od czerwca 2021 r.)
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Buckling and initial post-local buckling behaviour of cold-formed channel member flange
PublicationThe initial post-buckling behaviour of a cold-formed channel member flange after its local buckling is investigated. An axially compressed column or beam subjected to pure bending is considered. The member material is assumed to follow a linear stress-strain relationship. The governing non-linear differential equation of the problem is derived using the minimum total potential energy principle. An approximate solution for the equation...