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Wyniki wyszukiwania dla: VEHICLE ACOUSTICS
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Identification of acoustic event of selected noise sources in a long-term environmental monitoring systems
PublikacjaABSTRACT Undertaking long-term acoustic measurements on sites located near an airport is related to a problem of large quantities of recorded data, which very often represents information not related to flight operations. In such areas, usually defined as zone of limited use, often other sources of noise exist, such as roads or railway lines treated is such context as acoustic background. Manual verification of such recorded data...
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Thermal self-action effects for acoustic beams containing fronts in a Maxwell relaxing fluid
PublikacjaThis paper examines the thermal self-action of acoustic beams in a Maxwell relaxing fluid. This type of thermal self-action differs from that in a Newtonian fluid and behaves differently depending on a ratio of sound period and time of thermodynamic relaxation. The self-action which relates to sound beams containing shock fronts is also discussed. In addition, stationary and non-stationary types of self-action are considered.
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Time-Domain Description of Point-Source Acoustic Wavefields as a Useful Approach in Ultrasonic Techniques
PublikacjaIn traditional acoustics, field problems are usually treated in the frequency domain, broadband fields being reduced to superposition of harmonic spectrum components. However, this approach is inherently acausal and it is known that in case of arbitrary signals, the distribution-based, time-domain description can be more effective. The present paper is an attempt to expand the time-domain linear systems formalism onto space problems...
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Improvement of glass break acoustic signal detection via application of wavelet packet decomposition
PublikacjaThe main subject of the authors' research are non-contact methods of glass break detection based on analysis of the acoustic signal generated during the event. This problem has essential meaning for modern cost- effective alarm systems, particularly those installed into big buildings. The main difficulties of the matter are: transient character of the signal, great number of similar sounds (false signals, mainly accidental glass...
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Geographic information system for remote integration of diverse under-water acoustic sensor data
PublikacjaMaritime and port areas throughout the world are exposed to many different hazards, like pollution, terrorism and natural disasters. Early detection, identification and preparation of appropriateesponse strategies is especially important in the case of semi-enclosed basins like the Baltic Sea, mainly due to the marine ecosystems' continuous absorption of pollutants including oil, heavy metals and chemicals. Many of those agents...
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Air journal bearing utilizing near-field acoustic levitation: stationary shaft case
PublikacjaResults of a study to examine a unique idea of self-levitating journal bearing are presented in this paper. the idea represents a radical departure from the current bearing technology. it utilisesacoustic levitation, which relies on the sound energy radiated by an object supporting a load. acoustic levitation has been demonstrated to support loads of up to 10 kg. in order to support a load theacoustic wave emitted by the radiating...
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Automatic localization and continous tracking of mobile sound source using passive acoustic radar
PublikacjaA concept, practical realization and applications of the passive acoustic radar for localization and continuous tracking of fixed and mobile sound sources such as: cars, trucks, aircrafts and sources of shooting, explosions were presented in the paper. The device consists of the new kind of multi-channel miniature three dimensional sound intensity sensors invented by the Microflown company and a group of digital signal processing...
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Nonlinear generation of non-acoustic modes by low-frequency sound in a vibrationally relaxing gas
PublikacjaTwo dynamic equations referring to a weakly nonlinear and weakly dispersive flow of a gas in which molecular vibrational relaxation takes place. are derived. The first one governs an excess temperature associated with the thermal mode, and the second one describes variations in vibrational energy. Both quantities refer to non-wave types of gas motion. These variations are caused by the nonlinear transfer of acoustic energy into...
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Measurement of Seafloor Acoustic Backscatter Angular Dependence at 150 kHz Using a Multibeam Echosounder
PublikacjaAcoustic seafloor measurements with multibeam echosounders (MBESs) are currently often used for submarine habitat mapping, but the MBESs are usually not acoustically calibrated for backscattering strength (BBS) and cannot be used to infer absolute seafloor angular dependence. We present a study outlining the calibration and showing absolute backscattering strength values measured at a frequency of 150 kHz at around 10–20 m water...
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Acoustic journal bearing – Performance under various load and speed conditions speed conditions
PublikacjaThe paper presents results of experimental testing aiming at finding out what effect system of piezo-electric actuators (PZTs)attached to an aerodynamic journal bearing has on the magnitude of shaft's motion within the bearing operating at specified speed and load. The results clearly demonstrate effectiveness of PZTs in mitigating the shaft's motion thus contributing to the increased stability of the bearing. This stabilizing...
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A Numerical Study on Baseline-Free Damage Detection Using Frequency Steerable Acoustic Transducers
PublikacjaIn structural health monitoring (SHM) a considerable amount of damage detection algorithms based on guided waves (GW) have been developed. Most of them rely on extensive transducer networks, besides preliminary reference measurements of the structures. This originated a growing demand for hardware simplification and cost reduction of the wave-based SHM methods, driving the conception of new solutions enabling both: the reduction...
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Adaptive identification of sparse underwater acoustic channels with a mix of static and time-varying parameters
PublikacjaWe consider identification of sparse linear systems with a mix of static and time-varying parameters. Such systems are typical in underwater acoustics (UWA), for instance, in applications requiring identi- fication of the acoustic channel, such as UWA communications, navigation and continuous-wave sonar. The recently proposed fast local basis function (fLBF) algorithm provides high performance when identi- fying time-varying systems....
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Bimodal classification of English allophones employing acoustic speech signal and facial motion capture
PublikacjaA method for automatic transcription of English speech into International Phonetic Alphabet (IPA) system is developed and studied. The principal objective of the study is to evaluate to what extent the visual data related to lip reading can enhance recognition accuracy of the transcription of English consonantal and vocalic allophones. To this end, motion capture markers were placed on the faces of seven speakers to obtain lip...
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Stationary underwater channel experiment: Acoustic measurements and characteristics in the Bornholm area for model validations
PublikacjaThe underwater acoustical channel is time-variant, and even on small time scales there is often existing no ‘acoustical frozen ocean’. Popular is the use of WSSUS-channel transmission modeling (Wide-Sense Stationary Uncorrelated Scattering) for the stochastic description of bandpass signals in GSM mobile phones with moving participants; since this results in a halved number of model parameters. For underwater sound applications...
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Standing Acoustic Waves and Relative Nonlinear Phenomena in a Vibrationally Relaxing Gas-Filled Resonator
PublikacjaStanding acoustic waves in one-dimensional resonator filled with vibrationally relaxing gas, are studied. Two regimes of excitation of molecular vibrational degrees of freedom are considered, equilibrium and nonequilibrium. The acoustic energy enlarges with time in the non-equilibrium regime and decreases otherwise before formation of discontinuity. After that, it decreases due to nonlinear absorption and tends to zero in equilibrium...
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Computational investigations of acoustic radiation from end shields of small-power electric motor
PublikacjaW artykule omówiono rozwój metod modelowania własności akustycznych maszyn elektrycznych. Wskazano na pomijalny dotąd, znaczący udział drgań tarcz łożyskowych w emitowaniu hałasu przez silniki małej mocy. Na podstawie równania falowego potencjału prędkości wyprowadzono analityczne formuły do obliczeń akustycznych w polu bliskim tarczy łożyskowej. Zamieszczono uzyskane z serii obliczeń dla pracującego silnika, rozkłady ciśnienia...
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Comparison of backscattered sea bottom echo modelling in the acoustic pressure domain and in the intensity domain
PublikacjaPrzedstawiono dwie metody modelowania rozpraszania wstecznego na dnie morskim: modelowania ciśnienia akustycznego opartego na aproksymacji Kirchhoffa oraz modelowania natężenia echa przy założeniu dominacji rozpraszania niekoherentnego. Porównano i przedyskutowano wyniki w odniesieniu do problemu poszukiwania jak najwłaściwszego opisu zjawiska rozpraszania sygnału akustycznego na dnie.
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Passive layer cracking studies performed on A95056 Aluminum Alloy by DEIS and acoustic emission
PublikacjaZbadano proces pękania warstwy pasywnej na stopie aluminium A95056 w warunkach zmiennych naprężeń rozciągających i polaryzacji anodowej z wykorzystaniem techniki DEIS oraz emisji akustycznej (AE), jako metody porównawczej. Określono elektrochemiczne i mechaniczne przyczyny badanego procesu. Wyznaczono progową (krytyczną) wartość naprężeń, przy których zarejestrowano proces pękania warstwy pasywnej na badanym stopie aluminium. Badanemu...
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Complementary study with magnetic and acoustic techniques of A336 steel damage state due to creep
PublikacjaBadano możliwość detekcji w sposób nieniszczący zmian w mikrostrukturze stali A336 poddanej próbie pełzania. Testowano dwie magnetyczne techniki (klasyczny efekt Barkhausena i emisję magnetoakustyczną) oraz dwie nowe techniki ultradźwiękowe (pomiar współczynnika elasto-akustycznego oraz dwójłomność akustyczną). Wykazano, iż wyniki badań akustycznych są komplementarne do wyników badań magnetycznych.
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Shaping the SPL Spectra of the Acoustic Noise Emitted by Inverter-Fed Indu- ction Motors
PublikacjaW artykule przedstawiono nowe podejście do zmniejszania wpływu właściwości mechanicznych maszyny na emitowany przez nią hałas akustyczny. Dokonano identyfikacji mechanicznych rezonansów maszyny wykorzystując modulację RPWM z losowym wyborem częstotliwości nośnej oraz modulację sigma delta, dla której otrzymano relatywnie płaskie widmo prądu. Skonstruowano na tej podstawie funkcję gęstości prawdopodobieństwa wyboru częstotliwości...
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Optimizing acoustic field intesity algorithms using the sound ray surface density method.
PublikacjaW artykule przedstawiono zagadnienia optymalizacji algorytmów komputerowych obliczeń rozkładów natężeń pola akustycznego w akwenie w zależności od za- mierzonych warunków hydrologicznych pod kątem skrócenia czasu obliczń.
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Pursuing Analytically the Influence of Hearing Aid Use on Auditory Perception in Various Acoustic Situations
PublikacjaThe paper presents the development of a method for assessing auditory perception and the effectiveness of applying hearing aids for hard-of-hearing people during short-term (up to 7 days) and longer-term (up to 3 months) use. The method consists of a survey based on the APHAB questionnaire. Additional criteria such as the degree of hearing loss, technological level of hearing aids used, as well as the user experience are taken...
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Thermal Self-Action Effects of Acoustic Beam in a Gas with Reversible or Irreversible Chemical Reaction
PublikacjaThermal self-action of acoustic beam in a gas where an exothermic chemical reaction takes place, is studied. This kind of thermal self-action differs from that in a newtonian fluid. In dependence on the type of a chemical reaction, reversible or not, heating or cooling of a medium occurs. A beam in the case of the irreversible reaction may be unusually self-focusing. The self-action effects relating to wave beams containing shock...
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Time-domain description of point-source acoustic wavefields as a useful approach in ultrasonic techniques
PublikacjaIn traditional acoustics, field problems are usually treated in the frequency domain, broadband fields being reduced to superposition of harmonic spectrum components. However, this approach is inherently acausal and it is known that in case of arbitrary signals, the distribution-based, time-domain description can be more effective. The present paper is an attempt to expand the time-domain linear systems formalism onto space problems...
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Acoustic field and the entropy mode induced by it in a waveguide filled with some non-equilibrium gases
PublikacjaThe non-linear propagation of an acoustic beam in a rectangular waveguide is considered. The medium of sound propagation, is a gas where thermodynamically non-equilibrium processes take place: such as exothermic chemical reactions or excitation of vibrational degrees of a molecule’s freedom. The incident and reflected compounds of the acoustic field do not interact in the leading order in the case of periodic weakly nonlinear sound...
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Providing Differentiated Levels of Service Availability in VANET Communications
PublikacjaInter-vehicle communications seems to be a promising remedy not only for a number of road-safety issues, but also to improve the efficiency of road traffic, as well as to support the on-board infotainment applications. However, it often encounters disruptions due to high mobility of vehicles causing frequent failures of communication links. In this paper, we utilize the idea of multipath vehicle-to-vehicle routing to provide protection...
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Intelligent Vehicles Conference
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Modeling of performance and safety of a multi-task unmanned autonomous maritime vehicle = Modelowanie ruchu i bezpieczeństwa wielozadaniowego bezzałogowego autonomicznego pojazdu wodnego
PublikacjaAt the beginning of the paper the aim of research is presented. Then the method is introduced. Next, the unmanned autonomous maritime vehicle is briefly described. The following chapter concerns a model of vehicle performance including the ballasting and motion. Some information on an integrated steering, positioning and stabilization system of the vehicle is briefly presented in the paper. Such the system enables to obtain a fully...
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Modeling of Performance And Safety of a Multi-Task Unmanned Autonomous Maritime Vehicle / Modelowanie Ruchu i Bezpieczeństwa Wielozadaniowego Bezzałogowego Autonomicznego Pojazdu Wodnego
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Comparison of pavement noise properties on selected road sections using different CPX measuring systems: self-powered vehicle and special test trailer
PublikacjaThe recently published ISO standard intended to measure the noise properties of road surfaces in a standardized method (ISO 11819-2:2017) precisely defines measurement procedure of the influence of road surface on traffic noise. According to it, two types of test vehicles may be utilized: a self-powered vehicle fitted with one or more test tyres and a trailer towed by a separate vehicle with one or more test tyres mounted on the...
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Driver influence on tyre/road noise generated by vehicle in road traffic.Wpływ kierowcy na hałas generowany przez pojazd w ruchu drogowym.
PublikacjaW pracy omówiono wkływ stylu jazdy kierowcy oraz stanu technicznego wybranych zespołów pojazdu na jego hałas generowany w ruchu drogowym. Wpływ został przeanalizowany w aspekcie takich parametrów, jak: prędkość jazdy, obciążenie kół siłami wzdłużnumi i poprzecznymi, ciśnienie w ogumieniu, obciążenie pionowe kół, zbieżność i inne.
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AUDIO SIGNAL EQUALIZATION BASED ON IMPULSE RESPONSE OF A LISTENING ROOM AND MUSIC CONTENT REPRODUCED
PublikacjaA research study presents investigations of the influence of the room acoustics on the frequency characteristic of the audio signal playback. First, a concept of a novel spectral equalization method of the room acoustic conditions is introduced. On the basis of the room spectral response, a system for room acoustics compensation based on an equalizer designed is proposed. The system settings depend on music genre recognized automatically....
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World Electric Vehicle Journal
Czasopisma -
MicroRNA composition of plasma extracellular vesicles: a harbinger of late cardiotoxicity of doxorubicin
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Experimental verification of visual method for measuring displacements of contact line elements
PublikacjaThe increase of rail vehicles speed, as well as the increase of their power, puts high demands on the power delivery system for traction vehicles The most critical point in the vehicle's power supply circuit is the contact between the current collector and contact wires. Ensuring a reliable co-operation of the current collector and contact line, requires technical development...
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Analysis of the regenerative braking process for the urban traffic conditions
PublikacjaIn a regular drive system, with an internal combustion engine, vehicle braking is connected with the unproductive dissipation of kinetic and potential energy accumulated in the mass of the vehicle into the environment. This energy can constitute up to 70% of the energy used to drive a vehicle under urban conditions. Its recovery and reuse is one of the basic advantages of hybrid and electric vehicles. Modern traffic management...
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The Impact of Fuel Ethanol Content on Particulate Emissions from Light-Duty Vehicles Featuring Spark Ignition Engines
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The Impact of Alternative Fuels on Fuel Consumption and Exhaust Emissions of Greenhouse Gases from Vehicles Featuring SI Engines
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Integration of Multi-Source Geospatial Data from GNSS Receivers, Terrestrial Laser Scanners, and Unmanned Aerial Vehicles
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Integration of Multi-Source Geospatial Data from GNSS Receivers, Terrestrial Laser Scanners, and Unmanned Aerial Vehicles
PublikacjaThe analysis based on geospatial data from different measurement systems now constitutes a complex numerical and practical enterprise. The dynamic development of modern technologies enables rapid and precise acquisition of such data. Nonetheless, the diversity of reference systems is today one of the main challenges for their correct interpretation. The combined use of the processed measurement results and archival data in paper...
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High Efficiency Dual-Active-Bridge Converter with Triple-Phase-Shift Control for Battery Charger of Electric Vehicles
PublikacjaAn optimal modulation scheme with triple-phase-shift (TPS) control could increase the efficiency in the entire load range for a dual-active-bridge (DAB) converter under wide output voltage range conditions. Therefore, this study proposes a convergent approach to TPS mode selection, coupled with an optimal modulation scheme, ensuring the circuit’s efficiency over the entire range in the realm of a high-power and high-efficiency...
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Towards Audio Signal Equalization Based on Spectral Characteristics of a Listening Room and Music Content Reproduced
PublikacjaThis study presents investigations of the influence of the room acoustics on the frequency characteristic of the audio signal playback. First, the concept of a novel spectral equalization method of the room acoustic conditions is introduced. On the basis of the room spectral response, a system for room acoustics compensation based on an equalizer designed is proposed. The system settings depend on music genre recognized automatically....
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Processing of acoustical data in a multimodal bank operating room surveillance system
PublikacjaAn automatic surveillance system capable of detecting, classifying and localizing acoustic events in a bank operating room is presented. Algorithms for detection and classification of abnormal acoustic events, such as screams or gunshots are introduced. Two types of detectors are employed to detect impulsive sounds and vocal activity. A Support Vector Machine (SVM) classifier is used to discern between the different classes of...
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Investigation of Vibro-Acoustical Properties Using Eigenvalue Problem Solution and Wavelets
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Akustyczny obraz słowa na tle mowy etnicznej [The acoustic image of ethnic speech words]
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The use of Acoustic Emission to identification damages bearings the main and crank engines about the automatic ignition
PublikacjaThe article describes the laboratory tests, which make the first stage of the study concerning the use of the AE method to determine the technical state of the slide bearings in engines with self-ignition. The aim of the present tests was to compare the recorded signals in relation to the technical state of the material of the bearing bush and to check the possibility of using the AE method in determining the transition moment...
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Anomalous pressure dependence of acoustic phonons of AgGaSe2 investigated by inelastic neutron scattering to 4.3 GPa
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Impact of Tensile and Compressive Stress on Classical and Acoustic Barkhausen Effects in Grain-Oriented Electrical Steel
PublikacjaIn this paper, we present the results of the investigation of impact of tensile and compressive stress on the classical Barkhausen effect, magnetoacoustic emission (MAE) signal properties, and B(H) hysteresis loops for grain-oriented (GO) electrical steel. Samples have been glued to a nonmagnetic steel bar and stressed within elastic range (±800 μdef) by means of four-point bending method. The samples were cut out in two directions...
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Enhanced voice user interface employing spatial filtration of signals from acoustic vector sensor
PublikacjaSpatial filtration of sound is introduced to enhance speech recognition accuracy in noisy conditions. An acoustic vector sensor (AVS) is employed. The signals from the AVS probe are processed in order to attenuate the surrounding noise. As a result the signal to noise ratio is increased. An experiment is featured in which speech signals are disturbed by babble noise. The signals before and after spatial filtration are processed...
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Study of probe signal bandwidth influence on estimation of coherence bandwidth for underwater acoustic communication channel
PublikacjaA signal transmitted in a shallow Underwater Acoustic Communication (UAC) channel suffers from time dispersion due to the multipath propagation and the refraction phenomena. This causes intersymbol interference of the received signal and frequency-selective fading observed in its spectrum. Coherence bandwidth is one of the key transmission parameters used for designing the physical layer of a data transmission system to minimise...