Filtry
wszystkich: 606
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Wyniki wyszukiwania dla: UNDERWATER WET WELDING
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Toward Safe and Efficient Recovery of Gas Munitions Dumped at Sea
PublikacjaThe proposal of a system for the safe recovery of unexploded ordnance (UXO), chemical weapons (CW) and chemicalwarfare agents (CWA) dumped at sea mainly after WWI and WWII is described in this work. The proposed solutionaddresses the tasks required to neutralise thousands of tons of dumped material and the currently available solutionsand proposed ideas. Requirements concerning the features of a recovery system are defined and...
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Coastal zone monitoring using Sentinel-1 SAR polarymetry data
PublikacjaIn recent years the role of the surveillance and security of Polish boundaries has significantly increased. Polish coastal zone monitoring requires various approaches using various technological means in order to ensure the protection of Polish boundaries. In this paper, the authors discuss and present alternatives to underwater surveillance methods of coastal area analysis and monitoring using data retrieved from the newly developed...
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Evolution of artificial single-cell organisms foraging for resources in a 3-dimensional environment
PublikacjaForaging for resources is a simple cognitive task that even one-celled biological organisms can ac- complish. We present an Artificial Life system in which artificial unicellular organisms (animats) forage for food in a 3-dimensional simulated liquid environment. The movement of animats is controlled by evolving artificial gene regulatory networks encoded in linear genomes. When an animat consumes enough food, it produces offspring...
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Modeling of performance of a AUV vehicle towards limiting the hydro-acoustic field.
PublikacjaSome results of research devoted to the modeling of a AUV-Stealth vehicle performance towards limiting its hydro-acoustic field are presented in the paper. At the beginning the AUV-Stealth autonomous underwater vehicle concept is described. Then the method of research is introduced. Next the key design drivers of the AUV-Stealth vehicle are presented. Between them are the AUV-Stealth hull form, arrangement of internal spaces,...
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Hydrogen embrittlement of X2CrNiMoCuN25-6-3 super duplex stainless steel welded joints under cathodic protection
PublikacjaThe effect of cathodic polarization conditions on hydrogen degradation of X2CrNiMoCuN25-6-3 super duplex stainless steel welded joints, obtained using flux cored arc and submerged arc welding methods, was evaluated. Slow strain rate tensile tests of base material and welded specimens, ferrite content measurements, scanning electron microscopy observations, and statistical analysis were performed. It was found that hydrogenation...
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Study on Microstructure-Property Relationship of Inconel 617 Alloy/304L SS Steel Dissimilar Welds Joint
PublikacjaWelding of Inconel 617 (IN617) alloy and austenitic 304L SS steel has been attempted using the autogenous Laser Beam Welding (LBW) process. Characterization of dissimilar weldments was performed on either side of the fusion boundaries. The metallographic results showed that the inhomogeneous microstructure formation for weld metal contained columnar and cellular dendrites near the interface, whilst the columnar, cellular and equiaxed...
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Przyrządy do oceny jakości energii elektrycznej na przyykładzie elspec g4500
PublikacjaW artykule opisano przyrząd nowej generacji w dziedzinie pomiarów jakości energii elektrycznej typu ELSPEC G4500. Urządzenie pracujące w klasie A wprowadza nowy standard pomiarów polegający na wykonywaniu ciągłej rejestracji wszystkich interesujących użyt-kownika sygnałów. Zastosowane rozmiary pamięci i sposoby kompresji danych umożliwiają zapis na-wet wieloletniej obserwacji zjawisk zachodzących w sieci elektrycznej. Dane te...
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Modeling the global atmospheric transport and deposition of mercury to the Great Lakes
PublikacjaMercury contamination in the Great Lakes continues to have important public health and wildlife ecotoxicology impacts, and atmospheric deposition is a significant ongoing loading pathway. The objective of this study was to estimate the amount and source-attribution for atmospheric mercury deposition to each lake, information needed to prioritize amelioration efforts. A new global, Eulerian version of the HYSPLIT-Hg model was used...
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Assessing the Effects of the Road Surface and Weather Conditions on Road Safety
PublikacjaWhen transport is analysed for its safe delivery the focus is mainly on assessing the safety of roads and the risk of undesired events. These include road accidents, an occurrence which is relatively rare and random. Randomness means that accidents depend on several factors which are partly deterministic (can be controlled) and partly stochastic (random and unpredictable). The set of crash contributing factors can be classified...
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Measurements of transmission properties of Acoustic Communication Channels
PublikacjaTough transmission properties of shallow water acoustic channels (SWAC) highly limit the use of underwater acoustic communication (UAC) systems. An adaptive matching of modulation and signaling schemes to instantaneous channel conditions is needed for reliabledata communications. This creates, however, unique challenges for designers when compared to radio transmission systems. When communication system elements are in move, the...
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Searching of the buried objects in the sea bottom by means of noninvasive methods
PublikacjaSearching of objects on the seabed or under its surface currently is a challenge for a number of researchers interested in the sea bottom. The problem relates to the objects on the depths of up to several tens of meters from the surface of the seabed. Finding the objects is the subject of interest for a wide group of users starting from archaeologists, and ending on groups interested in marine safety, as well as in military application...
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An Intergrated Model of Motion, Steering, Positioning and Stabilization of an Unmanned Autonomous Maritime Vehicle
PublikacjaIn the paper the aim of an interdisciplinary research is presented. The research method is introduced. An object the unmanned autonomous maritime vehicle is briefly described. The key research problem concerns a combined model of the vehicle motion including the loads of lift and hydrodynamic nature. The model takes into account the gravity and displacement forces, resistance and thrust forces, lift and other hydrodynamic forces....
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System for characterisation and multidimensional imaging of seafloor using multibeam sonar data
PublikacjaMultibeam sonars are widely used in applications like high resolution bathymetry measurements, underwater object detection and imaging, etc. Also, they are the promising tool in seafloor characterisation and classification, having several advantages over conventional single beam echosounders. The proposed approach to seafloor classification relies on the combined use of three different techniques. In each of them, a set of descriptors...
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Experiment with small objects floating under water in the harbor security aspect.
PublikacjaObservation of the underwater area is the element of general trend which primary purpose is to protect and enhance the safety of the selected region. The aim of the paper is to present the acoustic characteristics of typical objects floating on the surface or under the water, which constitute some knowledge on how to detect these objects. Create a catalog of acoustic signatures and acoustic images of objects mostly floating under...
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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”...
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Acoustic Processor of the MCM Sonar
PublikacjaThis paper presents the concept of an acoustic processor of the mine countermeasure sonar. Developed at the Department of Marine Electronics Systems, Gdansk University of Technology, the acoustic processor is an element of the MG-89, a modernised underwater acoustic station. The focus of the article is on the modules of the processor. They are responsible for sampling analogue signals and implementing the algorithms controlling...
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NEW DESIGNS OF CENTRIFUGAL MAGNETIC FLUID SEALS FOR ROTATING SHAFTS IN MARINE TECHNOLOGY
PublikacjaThe centrifugal magnetic fluid seals have important advantage over the conventional centrifugal seals. They maintain very good sealing capacity at static, medium and high speeds of shaft rotation, with the increased seal lifetime, and minimum torque and static friction. These seals are particularly useful in cases when the angular shaft velocity varies and sometimes decreases to nearly or exactly zero, such as in flywheel applications,...
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Jeffreys heat conduction in coupled semispaces subjected to interfacial heating
PublikacjaA Jeffreys heat conduction problem for coupled semispaces subjected to the action of an interfacial heat source was defined. An analytical solution of the problem was derived for a polynomial specific power of the heat source using the Laplace transform approach. The asymptotic and parametric analysis was performed for different ratios of thermal conductivities , thermal diffusivities , thermal relaxation times and coefficients...
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The Influence of Modelling Material Zones on Strains and Stresses at Weld Toe Notch
PublikacjaThe latest development in the field of welding technology enabled prefabrication of thin-walled sandwich structures in an industrial scale. Sandwich structures fabricated of steel, or aluminium alloy plates and stiffeners are welded with the use of hi-power CO2 lasers. Strength analysis of such structures with the use of finite element method needs proper material modelling.In this paper the material model of steel sandwich panel...
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Methane emissions from mangrove soils in hydrologically disturbed and reference mangrove tidal creeks in southwest Florida
PublikacjaStudies have suggested that some mangrove soils might contribute to wetland methane (CH4) production and emissions, especially when the mangroves are disturbed. CH4 emissions were measured seasonally from nine locations on two mangrove creeks on Naples Bay in southwest Florida, USA. One of the tidal creeks has been impacted in the past few decades with alteration of upstream watersheds and freshwater inflows; the other creek was...
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Opracowanie technologii spawania naprawczego szyn poddźwigowych A120 oraz badania nieniszczące jakości szyn w DCT w Porcie Północnym
PublikacjaEkspertyza dotyczy realizacji zlecenia związanego z naprawą spoin szyn poddźwigowych na terenie terminalu kontenerowego - Deep Water Terminal (DCT) w Porcie Północnym w Gdańsku. W ramach opracowania: 1. Wykonano badania ultradźwiękowe (UT) i magnetyczno-proszkowe (MT) spoin czołowych szyn poddźwigowych typu A120, według schematu dostarczonego przez firmę SKANSKA S.A. 2. Wykonano analizę wyników badań...
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Negative CO2 Emission Gas Power Plant As Technology for Utilization of Sewage Sludge, Production of Electrical Energy, and CO2 Capture - Case of Chamber Under Transpiration Cooling
PublikacjaThis work focuses on the concept developed in the nCO2PP project, which aims to demonstrate a technology that allows to achieve negative CO2 emissions through Carbon Capture and Storage (CCS) applied to sewage sludge. A feedstock is first gasified, then the resulting syngas is burned in a semi-closed oxy-fuel gas turbine with pure oxygen and water, using the advantages of oxy-combustion, to ease the capture of CO2 in the resulting...
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Detection of Water on Road Surface with Acoustic Vector Sensor
PublikacjaThis paper presents a new approach to detecting the presence of water on a road surface, employing an acoustic vector sensor. The proposed method is based on sound intensity analysis in the frequency domain. Acoustic events, representing road vehicles, are detected in the sound intensity signals. The direction of the incoming sound is calculated for the individual spectral components of the intensity signal, and the components...
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„Eulerian – Eulerian” versus ,,Eulerian –Lagrangean” models of condensation
PublikacjaLiquid phase in the flowing vapor through stages of the steam turbine is the cause of a lot of failures. Nowadays, due to work of steam turbines at partial load, process of homogeneous and heterogeneous condensation still is current. The formation of drops of condensate under conditions other than nominal operation of turbine is a process still unknown. Engineers and designers involved in the development of power station machines...
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HOW EFFICIENT IS NOISE LABELING OF TIRES?
PublikacjaSince 2012 all new tires in Europe must be labeled. The label contains general information about tire performance concerning rolling resistance (that corresponds to fuel economy), noise emission and wet grip (only for passenger car tires). Measurements of noise performance of tires must be performed according to the Annex 3 of the Regulation No 117 of the Economic Commission for Europe of the United Nations. The regulation specifies...
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Synthesis, microstructure and electrical properties of nanocrystalline calcium doped lanthanum orthoniobate
PublikacjaThe single phase lanthanum orthoniobate with tetragonal structure has been synthesized by the means of mechanosynthesis method. The studies have shown the crystal structure of La0.98Ca0.02NbO4 depends on the synthesis stage. The samples were predominantly in the tetragonal phase with a trace amount of the monoclinic phase. The SEM studies of morphology and microstructure have shown nanocrystallinity of the materials. The Raman...
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Simulations of air and water flow in a model dike during overflow experiments
PublikacjaFlow in flood dikes, earth dams, and embankments occurs in variably saturated conditions, with pores of the earth material filled partly with water and partly with air. In routine engineering analysis, the influence of pore air is neglected and the air pressure is assumed equal to atmospheric. In some circumstances, for example, during overtopping of the dike by water, the effect of pore air on water flow and stability of the structure...
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A novel hierarchically-porous diamondized polyacrylonitrile sponge-like electrodes for acetaminophen electrochemical detection
PublikacjaA novel composite electrode material consisting of tangled fibrous polyacrylonitrile-based hierarchically-struc- tured nanocomposites has been produced by wet-spinning, carbonized and decorated with a carbon nano- architecture by microwave plasma-enhanced chemical vapor deposition and investigated as a metal-free electrode for the enhanced electrochemical detection of acetaminophen. Surprisingly, the hierarchical fiber ar- chitecture...
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High temperature proton conduction in LaSbO4
PublikacjaLanthanum orthoantimonate was synthesized using a solid‐state synthesis method. To enhance the possible protonic conductivity, samples with the addition of 1 mol% Ca in La‐site, were also prepared. The structure was studied by the means of X‐ray diffraction, which showed that both specimens were single phase. The materials crystallized in the space group P2 1 /n. Dilatometry revealed that material expands non‐linearly with the...
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Determination of ionic conductivity in the Bi-Si-O and Pb-Si-O glasses
PublikacjaImpedance spectroscopy measurements in various gas atmospheres were carried out in order to explain the doubts about the type of carriers and the mechanism of electrical conductivity in Bi-Si-O and Pb-Si-O glasses. In bismuth silicate glass, a typical ionic conductivity with oxygen ions as charge carriers was observed. The level of electrical conductivity of the glass at 400 °C was 5 × 10−8 S·cm−1 , with the activation energy of...
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Novel Class of Proton Conducting Materials—High Entropy Oxides
PublikacjaHere, for the first time, we present data on proton conductivity of high-entropy, single-phase perovskites. The BaZr0.2Sn0.2Ti0.2Hf0.2Ce0.2O3−δ, BaZr0.2Sn0.2Ti0.2Hf0.2Y0.2O3−δ, BaZr1/7Sn1/7Ti1/7Hf1/7Ce1/7Nb1/7Y1/7O3−δ, and BaZr0.15Sn0.15Ti0.15Hf0.15Ce0.15Nb0.15Y0.10O3−δ single-phase perovskites were synthesized. Before electrical measurements, materials were characterized using X-ray diffraction (XRD), scanning electron microscopy...
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Mathemathical model of radial passive magnetic bearing
PublikacjaIn the article mathematical radial model of passive magnetic bearings to ocean engineering units has been presented. The units application in underwater thrusters should increase propulsion systems durability and gives lower maintenance costs. The rotor of electric motor is hanging in magnetic field taken from radial passive magnetic bearings. However axial direction maintenance must be controlled with electromagnets and their...
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Web-based 3D processing and dissemination of multibeam sonar data
PublikacjaThe continuous detailed surveys of the various water bodies over time produce a large and ever-increasing volume and density of underwater sounding data. Three-dimensional data, such as those obtained by multibeam sonar systems, are quite complex to manage, and thus their growing numbers increase the pressure on development of new solutions dedicated to processing them. This paper presents a concept system for web-based dissemination...
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Influence of Natural Conditions on the Imaging of the Bottom of the Gdańsk Bay by Means of the Side Scan Sonar
PublikacjaThe interest in underwater resources is the reason for the development of modern hydroacoustic systems, including side sonars, which find numerous applications such as: research of seabed morphology and sediment characteristics, preparation of sea sediment maps, and even in special cases of biocenoses such as sea grass meadows, detection of specific targets at the bottom such as shipwrecks, mines, identification of suitable sites...
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The effect of pre-hydrogen charging on corrosion behaviour of superduplex stainless steel welded joints
PublikacjaThe paper presents results of research undertaken to determine the influence of hydrogen on passivity and corrosion resistance of 2507 super duplex stainless steel welded joints. Butt welded joints were made with low heat input using flux corded arc welding (FCAW) method. Coupons of 5.0 x 5.0 mm were cut from the welded joints containing weld metal (WM), heat affected zone (HAZ) and parent metal (PM). Hydrogen was introduced...
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Experimental and numerical investigations of ultimate strength of imperfect stiffened plates of different slenderness
PublikacjaThe objective of this study is to analyse the behaviour of compressed stiffened plates of different slenderness using experimental and numerical methods. The presented results are part of a long-term project to investigate the ultimate strength of geometrically imperfect structures subjected to different degradation phenomena, including corrosion degradation and locked cracks. Several specimens were subjected to a uniaxial compressive...
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Effect of Pin Shape on Thermal History of Aluminum-Steel Friction Stir Welded Joint: Computational Fluid Dynamic Modeling and Validation
PublikacjaThis article studied the effects of pin angle on heat generation and temperature distribution during friction stir welding (FSW) of AA1100 aluminum alloy and St-14 low carbon steel. A validated computational fluid dynamics (CFD) model was implemented to simulate the FSW process. Scanning electron microscopy (SEM) was employed in order to investigate internal materials’ flow. Simulation results revealed that the mechanical work...
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ISO test track influence on the EU tyre label noise value
PublikacjaIn 2009, the European Union (EU) introduced a directive governing the labelling of tyres, which underwent revision in 2020. This labelling system encompasses three key parameters related to tyre performance: wet grip (safety), rolling resistance (energy consumption), and external rolling noise (environmental impact). These label values serve as crucial information for customers seeking to purchase replacement tyres for their vehicles....
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Actual and reference evapotranspiration for a natural, temperate zone fen wetland – Upper Biebrza case study
PublikacjaEvapotranspiration is the key and predominant component of the water balance in wetlands. Direct evapotranspiration measurements are challenging in wetlands due to their remoteness and high surface water level. This article describes the actual (ETa and reference evapotranspiration (ET0) from a cultivated wet meadow located in the Biebrza National Park – the largest national park in north-east Poland, Central Europe. The data were...
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Example of Using Particle Swarm Optimization Algorithm with Nelder–Mead Method for Flow Improvement in Axial Last Stage of Gas–Steam Turbine
PublikacjaThis article focuses principally on the comparison baseline and the optimized flow efficiency of the final stage of an axial turbine operating on a gas–steam mixture by applying a hybrid Nelder– Mead and the particle swarm optimization method. Optimization algorithms are combined with CFD calculations to determine the flowpaths and thermodynamic parameters. The working fluid in this study is a mixture of steam and gas produced...
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Enhanced visible light photocatalytic activity of Pt/I-TiO2 in a slurry system and supported on glass packing
PublikacjaHighly photoactive I/TiO2, Pt/I-TiO2 nanocomposites were obtained using a hydrothermal and wet impregnation method. The incorporation of iodine and modification with 0.05 mol% of platinum leads to enhanced photocatalytic activity as compared to singly doped TiO2 due to the presence of impurity energy level in the structure of TiO2. X-ray diffraction, TEM microscopy, UV–Vis spectroscopy, X-ray photoelectron spectroscopy and BET...
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Conductivity, structure, and thermodynamics of Y2Ti2O7–Y3NbO7 solid solutions
PublikacjaThe defect fluorite yttrium niobate Y3NbO7 and pyrochlore yttrium titanate Y2Ti2O7 solid solutions have been synthesized via a solid state synthesis route. The resulting stoichiometry of the oxides is Y2+xTi2−2xNbxO7, where x = 0 to x = 1. All of the samples were single-phase; however, for those with a predominant fluorite phase, a small amount of additional pyrochlore phase was detected. The volume of the solid solution unit cells...
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Graphene-Coated PVDF Membranes: Effects of Multi-Scale Rough Structure on Membrane Distillation Performance
PublikacjaGraphene-coated membranes for membrane distillation have been fabricated by using a wet-filtration approach. Graphene nanoplatelets have been deposited onto PVDF membrane surfaces. Morphology and physicochemical properties have been explored to evaluate the changes in the surface topography and related effects on the membrane performance in water desalination. The membranes have been tested in membrane distillation plants by using...
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Trwałość spawanych instalacji wodnych wykonanych z nierdzewnych stali austenitycznych
PublikacjaW artykule przedstawiono dwa przypadki przedwczesnych uszkodzeń spawanych instalacji wodnych wykonanych ze stali odpornych na korozję. W celu ustalenia przyczyn uszkodzenia instalacji przeprowadzono badania metalograficzne, makro - i mikroskopowe oraz mikroanalizę składu chemicznego EDS na próbkach pobranych z reprezentatywnych miejsc. Wykazano, że głównymi przyczynami awarii rurociągów wody pitnej były niezgodności spawalnicze,...
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Shipping Low Frequency Noise and Its Propagation in Shallow Water
PublikacjaOne of the most significant factor influencing acoustical climate of the sea is underwater noise generated by moving ships. If the considered sea area has features of the shallow water, namely the wave frequency fulfils relation f < 10c/h, where c denotes phase speed of sound, and h is depths of the sea, then in certain distance from the wave source specific image of sound pressure distribution in the mean of wave modes appears....
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Shallow-Water Acoustic Communications in Strong Multipath Propagation Conditions
PublikacjaA phenomenon that has a strong impact on signal transmission conditions in Underwater Acoustic Communication (UAC) systems is multipath propagation. As a result of multipath propagation, the transmitted signal undergoes time dispersion which results in inter-symbol interference observed on the receiving side. Time dispersion is large, especially in horizontal channels in shallow waters which significantly limits the transmission...
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Effect of coarse grain aggregate on strength parameters of two-stage concrete
Publikacja. Two-stage concrete (TSC) is a special type of concrete that the method of its construction and implementation is different from conventional one. In TSC, coarse aggregate particles are first placed in the formwork and voids between them are subsequently injected with a special cementations mixture. TSC has been successfully used in many applications, such as underwater construction, casting concrete sections congested with reinforcement...
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An inverse algorithm for contact heat conduction problems with an interfacial heat source based on a first-order thermocouple model
PublikacjaInverse problems of contact heat conduction with an interfacial heat source are common in various fields of science, engineering and technology. In this study, an algorithm for their solution is developed based on an inverse parametric optimisation method with an impulse response function describing the heat partition and contact heat transfer. A first-order thermocouple model with a time constant parameter is embedded in the impulse...
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Progress in the post weld residual stress evaluation using Barkhausen effect meter with a novel rotating magnetic field probe
PublikacjaWe report the progress in post weld residual stress evaluation using Barkhausen effect (BE) meter with rotating magnetic field probe. The novel probe of the BE meter contains two C-core electromagnets and searching coil with ferrite antenna. This meter allows automatic measurements of BE intensity envelopes at different angles of magnetizing field. The full process of measurement at given position of the probe takes about only...
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Perfect thermal contact of hyperbolic conduction semispaces with an interfacial heat source
PublikacjaThe problem of thermal contact between two bodies with a heat source at their interface presents great scientific and practical interest. On the time scale of a nanosecond or shorter, heat propagation should be considered in the form of thermal waves of finite speeds. This study investigated the thermal behaviour of hyperbolic conduction semispaces in perfect thermal contact subjected to the action of an interfacial heat source....