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Search results for: underwater acoustic communications
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On Some Aspects of Fish Target Strength Estimation in Shallow Waters
PublicationThe theory of acoustic surveys for determining fish abundance are well established in fishery acoustics. The origins of the estimation are related to overcoming the problem of unknown position of target in the beam using statistical inversion. Although recently researchers use more sophisticated echosounders that provides more informative data allowing for direct solution it is known that the results are biased due to not ideally...
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Multimodal Surveillance Based Personal Protection System
PublicationA novel, multimodal approach for automatic detection of abduction of a protected individual, employing dedicated personal protection device and a city monitoring system is proposed and overviewed. The solution is based on combining four modalities (signals coming from: Bluetooth, fixed and PTZ cameras, thermal camera, acoustic sensors). The Bluetooth signal is used continuously to monitor the protected person presence, and in case...
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Kinedynamics of Spherical Wavefields in Fluid and Dielectric Continua
PublicationDistubances induced by physical sources in fluids or dielectrics maintain their primary character while propagating throughout either of these bi-dynamic continua. The paper defines and illustrates four sets of bi-fields based on four specific fundamental kinedynamic solutions to inhomogeneous wave equations related to quasi-point acoustic and electromagnetic sources.
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Analiza akustyki Teatru im. Marii Zańkowieckiej we Lwowie na podstawie pomiarów fotogrametrycznych i akustycznych
PublicationUtworzono model komputerowy pola akustycznego w sali widowiskowej Teatru i zbadano zakres możliwych zmian akustyki sali w związku z planowanym remontem sali. Model został skalibrowany na podstawie pomiarów akustycznych w stanie aktualnym. W obliczeniach wykorzystano program komputerowy CATT-Acoustic.
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The vortex flow caused by sound in a bubbly liquid
PublicationGeneration of vorticity in the field of intense sound in a bubbly liquid in the free half-space is considered. The reasons for generation of vorticity are nonlinearity, diffraction, and dispersion. Acoustic streaming differs from that in a Newtonian fluid. Under some conditions, the vortex flow changes its direction. Conclusions concern streaming induced by a harmonic or an impulse Gaussian beam.
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An Empirical System Loss Model for Body Area Networks in a Passenger Ferry Environment
PublicationThis paper presents a general empirical system loss model for estimating propagation loss in Body Area Networks in off-body communications at 2.45 GHz in a passenger ferry environment. The model is based on measurements, which were carried out in dynamic scenarios in the discotheque passenger ferry environment. The model consists of three components: mean system loss, attenuation resulting from the variable antenna position on...
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An Empirical System Loss Model for Body Area Networks in a Passenger Ferry Environment
PublicationThis paper presents a general empirical system loss model for estimating propagation loss in Body Area Networks in off-body communications at 2.45 GHz in a passenger ferry environment. The model is based on measurements, which were carried out in dynamic scenarios in the discotheque passenger ferry environment. The model consists of three components: mean system loss, attenuation resulting from the variable antenna position on...
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Sonar Pulse Detection Using Chirp Rate Estimation and CFAR Algorithms
PublicationThis paper presents a new approach to sonar pulse detection. The method uses chirp rate estimators and algorithms for the adaptive threshold, commonly used in radiolocation. The proposed approach allows detection of pulses of unknown parameters, which may be used in passive hydrolocation or jamming detection in underwater communication. Such an analysis is possible thanks to a new kind of imaging, which presents signal energy in...
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Modeling of performance of an AUV stealth vehicle. Design for operation.
PublicationIn the paper some results of research connected with modelling of performance and risk assessment of an AUV stealth vehicle are presented. A general approach to design of the stealth AUV autonomous underwater vehicle under consideration is introduced. The basic stealth characteristics of the AUV stealth vehicle are briefly described. The method of research is introduced. The AUV stealth vehicle concept is presented including the...
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Modelling of performance of an AUV stealth vehicle. Design for operation.
PublicationIn the paper some results of research connected with modelling of performance and risk assessment of an AUV stealth vehicle are presented. A general approach to design of the stealth AUV autonomous underwater vehicle under consideration is introduced. The basic stealth characteristics of the AUV stealth vehicle are briefly described. The method of research is introduced. The AUV stealth vehicle concept is presented including the...
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AUTONOMOUS PLATFORM TO PROTECT MARITIME INFRASTRUCTURE FACILITIES
PublicationProblems regarding the security of maritime infrastructure, especially harbours and offshore infrastructure, are currently a very hot topic. Due to these problems, there are some research projects in which the main goal is to decrease the gap and improve the methods of observation in the chosen area, for both in-air and underwater areas. The main goal of the paper is to show a new complex system for improving the security of the...
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Joint Working Conference on Secure Information Networks: Communications and Multimedia Security
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A low complexity double-talk detector based on the signal envelope
PublicationA new algorithm for double-talk detection, intended for use in the acoustic echo canceller for voice communication applications, is proposed. The communication system developed by the authors required the use of a double-talk detection algorithm with low complexity and good accuracy. The authors propose an approach to doubletalk detection based on the signal envelopes. For each of three signals: the far-end speech, the microphone...
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INVESTIGATION OF THE LOMBARD EFFECT BASED ON A MACHINE LEARNING APPROACH
PublicationThe Lombard effect is an involuntary increase in the speaker’s pitch, intensity, and duration in the presence of noise. It makes it possible to communicate in noisy environments more effectively. This study aims to investigate an efficient method for detecting the Lombard effect in uttered speech. The influence of interfering noise, room type, and the gender of the person on the detection process is examined. First, acoustic parameters...
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Investigation of the laser generated ablation plasma plume dynamics and plasma plume sound wave dynamics
PublicationWe investigated the dynamics of laser generated ablation plasma plume expanding in ambient air and dynamics of the sound wave generated by the expanding plasma. The ablation plasma plume was generated during nanosecond laser micromachining of the thin metal foil. The time-resolved images of the expanding plasma plume and sound wave were captured at several nanosecond intervals. Using captured images the expansion rate of the plasma...
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Malaysia International Conference on Communications (Joint IEEE Malaysia International Conference on Communications and IEEE International Workshop on Intelligent Signal Processing and Communication Systems [MICC/ISPACS])
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Active feedback noise control in the presence of impulsive disturbances
PublicationThe problem of active feedback control of a narrowband acoustic noise in the presence of impulsive disturbances is considered. It is shown that, when integrated with appropriately designed outlier detector, the proposed earlier feedback control algorithm called SONIC is capable of isolating and rejecting noise pulses. According to our tests this guarantees stable and reliable operation of the closed-loop noise cancelling...
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The nonlinear effects of sound in a liquid with relaxation losses
PublicationThe nonlinear effects of sound in electrolyte with a chemical reaction are examined. The dynamic equations that govern non-wave modes in the field of intense sound are derived, and acoustic forces of vortex, entropy, and relaxation modes are determined in the cases of low-frequency sound and high-frequency sound. The difference in the nonlinear effects of sound in electrolyte and in a gas with excited vibrational degrees of molecules,...
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Processing of Hydroacoustic and LiDAR Data for Three-dimensional Surface Reconstruction
PublicationThe technologies of sonar and laser scanning are commonly used for obtaining spatial information about underwater and over ground environments in the form of point clouds. Since this data model has known disadvantages, a more practical solution of visualising such data involves the creation of solid three-dimensional meshes composed of edges and facets. In this paper, several methods for 3D shape reconstruction of data obtained...
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Control of mass concentration of reagents by sound in a gas with nonequilibrium chemical reactions
PublicationThe weakly nonlinear dynamics of a chemically reacting gas is studied. Nonlinear interaction of acoustic and nonacoustic types of motion are considered. We decompose the base equations using the relationships of the gas-dynamic perturbations specific for every type of motion. The governing equation for the mass fraction of a reagent influenced by dominating sound is derived and discussed. The conclusions concern the equilibrium...
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Sounding Mechanism of a Flue Organ Pipe—A Multi-Sensor Measurement Approach
PublicationThis work presents an approach that integrates the results of measuring, analyzing, and modeling air flow phenomena driven by pressurized air in a flue organ pipe. The investigation concerns a Bourdon organ pipe. Measurements are performed in an anechoic chamber using the Cartesian robot equipped with a 3D acoustic vector sensor (AVS) that acquires both acoustic pressure and air particle velocity. Also, a high-speed camera is employed...
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Automatic labeling of traffic sound recordings using autoencoder-derived features
PublicationAn approach to detection of events occurring in road traffic using autoencoders is presented. Extensions of existing algorithms of acoustic road events detection employing Mel Frequency Cepstral Coefficients combined with classifiers based on k nearest neighbors, Support Vector Machines, and random forests are used. In our research, the acoustic signal gathered from the microphone placed near the road is split into frames and converted...
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Application a laboratory stand for multi-symptoms tests for high cyclic fatigue of constructional material
PublicationThis paper describes a need of diagnostics present ship plants according to current technical state. In order to reach competent physical quantity describing fatigue of materials by congregated energy. This paper describes using some diagnostics methods (acoustic emission AE, vibration, thermovision, deformation) in order to definition fatigue state of construction material. The author tries to find correlation between measured...
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The AC motor voltage and audible noise waveforms in ship’s electrical drive systems with frequency converters
Open Research DataThe presented dataset is part of research focusing on the impact of the ship's electrical drive systems with frequency converters on vibrations and the level of audible noise on ships.
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User Mobility’s Influence on System Loss in Off-Body BAN Scenarios
PublicationIn this paper, a measurement campaign for off-body communications in an indoor environment is investigated for a set of on-body antennas. The channel impulse response was measured with the user approaching and departing from an off-body fixed antenna using two user dynamics: standing at fixed positions and walking. The processing of the measurement data allowed to evaluate system loss statistics. Different antenna configurations...
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Mobility’s Influence on System Loss in Off-Body BAN Scenarios
PublicationIn this paper, a measurement campaign for off body communications in an indoor environment is investigated for a set of on-body antennas. The channel impulse response was measured with the user approaching and departing from an off-body fixed antenna using two user dynamics, standing at fixed positions and walking. The processing of the measurement data allowed to evaluate system loss statistics. Different antenna configurations...
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Identifying and Mitigating the Negative Effects of Power in Organizations
PublicationThis article investigates the possible negative effects of power in organizations. It demonstrates how holding power may affect an individual’s perception of others, actions, and cognition. Ways in which power may have a detrimental effect on different aspects of a manager’s functioning within an organization, including building relationships, communication, and performance are analyzed. It is argued that individuals are unaware...
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RESOURCE ALLOCATION IN DAB+ BROADCASTING SYSTEM
PublicationWith over two billion receivers operating worldwide, radio transmission is by far the most accessible medium. It has been a part of our lives since the 1920’s and has become one of the most trusted and friendly mass media. Today, its popularity is still strong, despite the outcome of many electronic media. In order to transform the radio into a viable medium of the 21st century, it will have to migrate from analogue to digital...
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RECODIS: Resilient Communication Services Protecting End-user Applications from Disaster-based Failures
PublicationDisaster-based failures can seriously disrupt any communication network, making its services unavailable. Such disruptions may be caused by natural disasters, technology-related failures, or malicious attacks, and they are observably increasing in number, intensity and scale. When network services that are a part of critical infrastructure become unavailable, commercial and/or societal problems are inevitable. The issue of limiting...
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Adaptacja akustyczna pomieszczenia wykładowego - studium przypadku
PublicationW niniejszej pracy przedstawiono analizę rozkładu pola akustycznego sali wykładowej znajdującej się w budynku Wydziału Elektroniki i Telekomunikacji Politechniki Gdańskiej. Badania przeprowadzono metodą pomiarową oraz symulacyjną z wykorzystaniem programu Odeon. Wybór parametrów oceny akustyki wnętrz sugerowany jest wymaganiami stawianymi pomieszczeniom lekcyjnym z zaznaczeniem multimedialnego charakteru wykładów prowadzonych...
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BADANIA ODBIOROWE ŁUKOWEJ KŁADKI DLA PIESZYCH 10T NAD DROGĄ S8 W WARSZAWIE
PublicationThe paper presents in situ load testing of the newly build footbridge over S8 expressway in Warsaw. The most characteristic thing for the structure is a shape of arch girders, which correspond with adjacent half-tunnel acoustic baffles. The paper consists of description of the structure, results of the in-situ static and dynamic load testing, results of the numerical simulations, comparative analysis and final conclusions on the...
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Split-Beam Echosounder Data from Puck Bay
PublicationThe acoustic data was collected in 2018–2019 in the Bay of Puck in the seasons: autumn, winter, spring. The data was collected during the day and night using three split-beam echosounders with frequencies of 38 kHz, 120 kHz and 333 kHz at a designated study area not far from the city of Hel, while the ship was sailing. To ensure data quality, the echosounders were calibrated and passive noise was measured.
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Robust algorithm for active feedback control of narrowband noise
PublicationThe problem of active control of narrowband acoustic noise is considered. It is shown that the proposed earlier feedback control algorithm called SONIC (self-optimizing narrowband interference canceller), based on minimization of the L2-norm performance measure, can be re-derived using the L1 approach. The resulting robust SONIC algorithm is more robust to heavy-tailed measurement noise, such as the αlpha-stable noise, than the...
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Facile synthetic route to selectively protected spermidine homologues
PublicationW wyniku opracowanej procedury otrzymano kilka selektywnie chronionych homologów spermidyny. Reakcja cyjanoetylowania monochronionych diamin pozwoliła na otrzymanie nitryli, które przekształcano w amidy pierwszorzędowe. Degradacja Hofmanna amidów doprowadziła do otrzymania finalnych związków.
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Context dependent effects of ascorbic acid treatment in TET2 mutant myeloid neoplasia
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Pd-catalysed general access to 7-membered N/O-heterocyclic compounds as potential agents against inflammation
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Infrared response of multiwalled boron nitride nanotubes
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Magnesium porphyrazine with peripheral methyl (3,5-dibromophenylmethyl)amino groups – synthesis and optical properties
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Synthesis of Novel Polycationic Quaternary Di- and Trispirocyclic Benzenes
PublicationTreatment of hexakis(bromomethyl)benzene with a cyclic amine {morpholine, 1-methylpiperazine, 1-(2-hydroxyethyl)piperazine, isonipecotamide, 4-hydroxypiperidine, 4-[3-(4-piperidyl)propyl]-1-piperidineethanol} gave a range of di- and trispirocyclic ammonium salts in satisfactory yields (22-62%). Presumably, the electrostatic and repulsion forces play an important role in their formation. The structure in soln. and the protonation...
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A Convenient Synthesis of Monocationic 1-[(Cyclic amidino)methyl]thymines
Publication1-[(Cyclic amidino)methyl]thymines have been conveniently synthesized from thymine in a three-step procedure via 1-cyanomethyl- and 1-[(thiocarbamoyl) methyl]thymines. The above synthetic intermediates were obtained in good yields by improved methods.
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Preparation of 1-[Ω-(1,4,5,6-Tetrahydropyrimidin-2-yl)alkyl]thymines
PublicationOne-stage prepn. of the hydrochloride salts of 1-[ω-(1,4,5,6-tetrahydropyrimidin-2-yl)alkyl]-thymines, e.g. I, from 1-(ω-cyanoalkyl)thymines and a 1:1-mixt. of 1,3-diaminopropane and ethanol satd. with hydrogen sulfide is described. 1-(2-Cyanoethyl)-thymine gave a facile reversal of the Michael reaction to thymine under the conditions used. The reaction of 1,3-bis(3-cyanobenzyl)thymine with the above reagent produced 1,3-bis[3-(1,4,5,6-tetrahydropyrimidin-2-yl)benzyl]thymine.
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4-(Cyclic-amidino)phenols. Preparation and Use in a Diamidine Synthesis
PublicationThe Pinner synthesis was applied to the prepn. of phenols 4-substituted with cyclic amidines in high yields from readily available 4-HOC6H4C(OMe):NH.HCl and aliph. diamines. An alternative attempt was made to convert 4-HOC6H4CSNH2 to 4-(1,4,5,6-tetrahydro-5-hydroxy-2-pyrimidinyl)phenol. A procedure for the prepn. of 3,6-bis(4-hydroxyphenyl)-1,2,4,5-tetrazine is reported. The syntheses of 2,4-bis[4-(4,5-dihydro-1H-imidazol-2-yl)phenoxy]pyrimidine...
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Methods for the synthesis of xanthine-derived polycyclic fused systems
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Mesenchymal stem cells transfer mitochondria to allogeneic Tregs in an HLA-dependent manner improving their immunosuppressive activity
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Distinguishing between polymorphic forms of linezolid by solid-phase electronic and vibrational circular dichroism
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Fe-promoted CuO/CeO2 catalyst
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Surface properties of wustite based iron-cobalt catalysts for ammonia synthesis reaction
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Pitting corrosion in steel and electrochemical noise intensity
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Determination of electrode impedance by means of exponential chirp signal
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The time dependence of pit creation impedance spectra
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