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Wyniki wyszukiwania dla: acoustic diffuser
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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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Acoustic imaging of selected areas of Gdansk Bay with the aid of parametric echosounder and side-scan sonar
PublikacjaThe article presents and analyses the data recorded during sounding of the Gdansk Bay seabed with the aid of a parametric echosounder and a side-scan sonar. The accuracy of seabed structure examination, as a condition for obtaining valuable results, requires correct configuration of echolocation devices and proper calibration of peripheral devices, such as the survey unit geographical position sensor – GPS, the navigation unit,...
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A method for testing the wide-sense stationary uncorrelated scattering assumption fulfillment for an underwater acoustic channel
PublikacjaWide-sense stationary and uncorrelated scattering (WSSUS) assumptions are often applied for the statistical description of wireless communication channels. However, in the case of underwater acoustic channels the WSSUS model is of limited value. The degree of similarity of in-phase and quadrature components of the channel impulse response, measured with the use of bandpass modulated signals, can be used as an indicator of WSSUS...
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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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NON-STATIONARY THERMAL SELF-ACTION OF ACOUSTIC BEAMS CONTAINING SHOCK FRONTS IN THERMOCONDUCTING FLUID
PublikacjaNon-stationary thermal self-action of a periodic or impulse acoustic beam containing shock fronts in a thermoconducting Newtonian fluid is studied. Self-focusing of a saw-tooth periodic and impulse sound is considered, as well as that of a solitary shock wave which propagates with the linear sound speed. The governing equations of the beam radius are derived. Numerical simulations reveal that the thermal conductivity weakens the...
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Microcracking monitoring and damage detection of graphene nanoplatelets-cement composites based on acoustic emission technology
PublikacjaThis study aims to identify the micro-cracking pattern and structural applications of cement composites replaced with 0 wt%, 0.04 wt%, and 0.08 wt% contents of graphene nanoplatelets (GNPs) over cement weight through acoustic emission (AE) monitoring under mechanical degradation. The ultraviolet-visible spectroscopy (UV–vis) results showed that at 60 min sonication period, GNP-4 showed maximum absorbance rate of 16.15% compared...
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Comparing traffic intensity estimates employing passive acoustic radar and microwave Doppler radar sensor
PublikacjaThe purpose of our applied research project is to develop an autonomous road sign with built-in radar devices of our design. In this paper, we show that it is possible to calibrate the acoustic vector sensor so that it can be used to measure traffic volume and count the vehicles involved in the traffic through the analysis of the noise emitted by them. Signals obtained from a Doppler radar are used as a reference source. Although...
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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...
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Simulation of Direct-Sequence Spread Spectrum Data Transmission System for Reliable Underwater Acoustic Communications
PublikacjaUnderwater acoustic communication (UAC) system designers tend to transmit as much information as possible, per unit of time, at as low as possible error rate. It is a particularly difficult task in a shallow underwater channel in which the signal suffers from strong time dispersion due to multipath propagation and refraction phenomena. The direct-sequence spread spectrum technique (DSSS) applied successfully in the latest standards...
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Estimating Traffic Intensity Employing Passive Acoustic Radar and Enhanced Microwave Doppler Radar Sensor
PublikacjaInnovative road signs that can autonomously display the speed limit in cases where the trac situation requires it are under development. The autonomous road sign contains many types of sensors, of which the subject of interest in this article is the Doppler sensor that we have improved and the constructed and calibrated acoustic probe. An algorithm for performing vehicle detection and tracking, as well as vehicle speed measurement,...
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Robust identification of glass breaks acoustic signals based on Wavelet transformation and Rock Solid Attributes.
PublikacjaStosowane w systemach alarmowych współczesne metody detekcji zbicia szyby, wykorzystują zwykle analizę sygnałów akustycznych towarzyszących temu procesowi. Podstawową metodą identyfikacji jest detekcja kilku charakterystycznych częstotliwości, niestety takie podejście wprowadza możliwość zafałszowania wyniku detekcji przez sygnały fałszywe, które mają zbliżaną charakterystykę widmową. Znacznie lepsze rezultaty osiągnąć można stosując...
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Application of inserts for suppression of coupled dynamic-acoustic effects during confined granular flow in silos
PublikacjaArtykuł omawia sposoby redukcji efektów dynamiczno-akustycznych w silosach. Do redukcji zastosowano różne wkładki. Zbadano wpływ kształtu i liczby wkładek w doświadczeniach. Na podstawie wyników doświadczalnych opracowano metodę redukcji efektów dynamiczno-akustycznych w dużych stalowych silosach.
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Searching of the buried objects into the sea bottom by means of nonlinear acouctic methods
PublikacjaThe main goal of this paper is to introduce the methodology of preparing the area for investigations that will be carried out at the sea. As the first step there is recognition of the basic method both in the theory as well as experimental investigation. There were taken into account the nonlinear methods. These ones are very promising methods that have very interesting features, very convenient for examinations of the seabed structure....
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The use of Yttrium-90 Ibritumomab Tiuxetan ( 90 Y-IT) as a consolidation therapy in high-risk patients with diffuse large B-cell lymphoma ineligible for autologous stem-cell transplantation
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Hearing aid operating in acoustical free field
PublikacjaAparatowanie bardzo małych dzieci (od 5 miesiąca życia) za pomocą standardowych protez słuchu natrafia na wiele trudności natury praktycznej. Dotyczy to procesu dopasowania aparatu słuchowego, czyli doboru jego ustawień stosownie do aktualnych charakterystyk ubytku słuchu dzieci. Tymczasem wczesne aparatowanie jest zagadnieniem o ogromnym zanczeniu dla rozwoju słuchu, mowy i ogólnej inteligencji dziecka. Referat prezentuje uzyskane...
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Usage of concentrated spectrogram for analysis of acoustical signals
PublikacjaA novel precise method of signal analysis in the time-frequency domain is presented. A signal energy distribution is estimated by discard and displacement of energy parts of the classical spectrogram. A channelized instantaneous frequency and a local group delay are used in order to energy replacement. Additionally, newly introduced representations such as: a channelized instantaneous bandwidth and a local group duration are used...
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3d Visualization of Seabed from Multibeam Sonar Records Using TriangularIrregular Mesh. W: [CD-ROM] Forum Acusticum Sevilla 2002. 3rd European Con-gres on Acoustics. XXXIII Spanish Congress on Acoustics-TECNIACUSTICA 2002.European and Japanese Symposium on Acoustics. Sevilla, Spain 16-20 Septem- ber 2002. Madrid: Soc. Espanola de Acustica**2002 vol. 33, [6 s.] 4 rys. bibliogr. 6 poz. ISBN: 84-87985-06-8 Special Issue of the Journal Revista de Acustica, vol.33, ano 2002. Trójwym. wizual.dna mors. z danych pochodz. z echosond wielowiąz. z wykorz.niergul.siat.TIN.
PublikacjaPrzedstawiono sposób trójwymiarowej wizualizacji dna morskiego przy wyko-rzystaniu siatki nieregularnej (TIN) otrzymanej w wyniku triangularyzacjioraz porównano otrzymane wyniki z rzeczywistymi pomiarami batymetrycznymidna Bałtyku Południowego.
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Changes in conditions of acoustic wave propagation in the Gdansk deep as an effect of climate changes in the Baltic Sea region
PublikacjaThe article presents the results from a research project investigating acoustic climate changes in the Gdansk Deepbased on data extending from 1902 to 2019. This part of the southern Gotland Basin, is rarely discussed in thescientific literature.The speed of sound in the seawater is a function of temperature, salinity, and depth. In such shallow sea asBaltic Sea, the impact of depth is not substantial....
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Generation of vorticity motion by sound in a chemically reacting gas and inversion of acoustic streaming in the non-equilibrium regime
PublikacjaBadanie dotyczy nieliniowych pobudzeń modu wirowego wywoływanych przez straty momentu pędu w gazie, w którym zachodzą reakcje chemiczne. Zostało wyprowadzone chwilowe dynamiczne równanie dla modu wirowego. Zawiera ono nieliniową siłę akustyczną co pokazuje, że powodem interakcji między modami akustycznym i wirowym jest nieliniowość. Równanie pozwala jako przyczynę ruchu wirowego rozważać zarówno dźwięk okresowy, jak i aperiodyczny....
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Development of linear projecting in studies of non-linear flow. Acoustic heating induced by non-periodic sound
PublikacjaRównanie bilansu energii rozkłada się na sumę dwóch równań, opisujących dynamikę fali akustycznej i wywołanego przez nią ogrzewania. Nowe równanie dynamiczne stosowane jest dla opisu dźwięku nieokresowego zarówno jak okresowego. Rozpatruje się geometrię wiązkową. Omówiane są poszczególne udziały przewodnictwa cieplnego i lepkości w ogrzewaniu akustycznym. Równania stanu ośrodka propagacji są uwzględniane w najbardziej ogólnej postaci.
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Research and development on underwater acoustic systems at Polish Naval Academy and Gdansk University of Technology for the Polish Navy
PublikacjaWe wstępie artykułu wymieniono korzystne aspekty prawie pięćdziesięcioletniej współpracy obu Uczelni z polską Marynarką Wojenną. W dalszych częściach omówiono prace z dziedziny hydroakustyki wykonywane na rzecz Marynarki Wojennej w ciągu ostatnich dziesięciu lat. W Akademii MW w tym okresie były to głównie prace związane z pomiarami i analizami hydroakustycznych pól okrętów wraz z aplikacjami technicznymi tych analiz oraz aplikacje...
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Application of Time-Frequency Analysis of Acoustic Signal to Detecting Flat Places on the Rolling Surface of a Tram Wheel
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A study on microcrack monitoring in concrete: discrete element method simulations of acoustic emission for non-destructive diagnostics
PublikacjaThe research is focused on the monitoring of fracture evolution in concrete beams under three-point bending using the acoustic emission technique and the discrete element method. The main objective of the study was to numerically and experimentally investigate the mechanism behind the generation of elastic waves during acoustic emission events and their interaction with micro- and macro-cracking in concrete beams under monotonic...
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Measurements and Visualization of Sound Intensity Around the Human Head in Free Field Using Acoustic Vector Sensor
PublikacjaThis paper presents measurements and visualization of sound intensity around the human head simulator in a free field. A Cartesian robot, applied for precise positioning of the acoustic vector sensor, was used to measure sound intensity. Measurements were performed in a free field using a head and torso simulator and the setup consisting of four different loudspeaker configurations. The acoustic vector sensor was positioned around...
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Effect of temperature and ionic strength on volumetric and acoustic properties of solutions of urea alkil derivatives in aqueous NaCl
PublikacjaThe present work was undertaken to study volumetric and acoustic properties for diluted solutions of tetramethylurea in pure water and for urea, n-propylurea, n-butylurea and tetramethylurea in 0.5 or 1 moldm3 aqueous solutions of sodium chloride. This paper presents measured values of densities and sound velocities at T = (288.15, 298.15 and 308.15) K. From these data the apparent molar volumes, , adiabatic compressibilities,...
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Minimizing Distribution and Data Loading Overheads in Parallel Training of DNN Acoustic Models with Frequent Parameter Averaging
PublikacjaIn the paper we investigate the performance of parallel deep neural network training with parameter averaging for acoustic modeling in Kaldi, a popular automatic speech recognition toolkit. We describe experiments based on training a recurrent neural network with 4 layers of 800 LSTM hidden states on a 100-hour corpora of annotated Polish speech data. We propose a MPI-based modification of the training program which minimizes the...
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POSSIBILITY OF IDENTIFICATION OF TECHNICAL CONDITION OF BEARINGS FOR SELF-IGNITION ENGINES BY APPLICATION OF ACOUSTIC EMISSION AS A DIAGNOSTIC SIGNAL
PublikacjaThis paper presents the results of empirical studies where the acoustic emission (AE) method was applied to identify the technical condition of sliding surfaces of main and crank bearings for main diesel engines. The test results indicate that the measurements of the AE parameters allow the technical condition identification for bearings of this type. The results refer to the measurements of the parameters for AE generated in the...
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Evaluation of sound event detection, classification and localization in the presence of background noise for acoustic surveillance of hazardous situations
PublikacjaAn evaluation of the sound event detection, classification and localization of hazardous acoustic events in the presence of background noise of different types and changing intensities is presented. The methods for separating foreground events from the acoustic background are introduced. The classifier, based on a Support Vector Machine algorithm, is described. The set of features and samples used for the training of the classifier...
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Changes in conditions of acoustic wave propagation in the Gdansk deep as an effect of climate changes in the Baltic Sea region
PublikacjaThe article presents the results from a research project investigating acoustic climate changes in the Gdansk Deep based on data extending from 1902 to 2019. This part of the southern Gotland Basin, is rarely discussed in the scientific literature. The speed of sound in the seawater is a function of temperature, salinity, and depth. In such shallow sea as Baltic Sea, the impact of depth is not substantial. The other two factors...
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Reliable OFDM Data Transmission with Pilot Tones and Error-Correction Coding in Shallow Underwater Acoustic Channel
PublikacjaThe performance of Underwater Acoustic Communication (UAC) systems are strongly related to the specific propagation conditions of the underwater channel. Horizontal, shallow-water channels are characterised by extremely disadvantageous transmission properties, due to strong multipath propagation and refraction phenomena. The paper presents the results of communication tests performed during a shallow, inland-water experiment with...
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Application of Rock Solid Attributes for robust identyfication of glass breaks acoustic signals via wavelet transformation
PublikacjaWspółczesne metody detekcji zbicia szyby stosowane w systemach alarmowych, wykorzystują analizę sygnałów akustycznych (ze względu na osiągi i koszty). Często używane metody analizy bazują na detekcji kilku charakterystycznych częstotliwości, jednak nie są to metody odporne na sygnały fałszywe. Jak wskazują niektóre pozycje literatury, zastosowanie metod JTFA może być bardziej użyteczne do analizy tego rodzaju sygnałów. Aby opracować...
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Observation of sub-bottom sediment in the southern baltic by means of onlinear acoustics method
PublikacjaW pracy przedstawiono wyniki badań struktury osadów dennych Bałtyku Południowego metodami akustyki nieliniowej.
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Comparing some convolution-based methods for creation of surround sound. W: [CD-ROM] Collected papers. First Pan-American/Iberian Meeting on Acoustics. 144 Meeting of the Acoustical Society of America. III Iberoamerican Cong- ress of Acoustics. 9o Mexican Congress of Acoustics. Cancun, Q. R. Mxico, 2-6 Dec. 2002. [B.m.:ASA]**2002 paper 2pPP22, 7 s. 8 rys. 1 tab. bibliogr. 12 poz. system nagrań dźwięku dookólnego z wykorzystaniem splotu odpowiedzi impul- sowej sali.
PublikacjaW referacie przedstawiono eksperymenty związane z symulacją dźwięku dookól-nego w sali koncertowej. W tym celu wykorzystano splot odpowiedzi impulsowejz danego wnętrza (wielokanałowe nagrania odpowiedzi impulsowej) z nagraniamiz komory bezechowej. Uzyskany w ten sposób sygnał został następnie przypisa-ny do odpowiednich kanałów w systemie dookólnym. Uzyskane w ten sposób nag-rania były następnie porównywane w testach subiektywnych...
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CYP17Genotypes Differ in Salivary 17-β Estradiol Levels: A Study Based on Hormonal Profiles from Entire Menstrual Cycles
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Analiza akustyczna jako parametr klasyfikacji formalnej homonimii międzyjęzykowej [The acoustic analysis as a parameter for classifying interlingual homonymy]
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Solvation of alkaline earth metal ions in N,N-dimethylformamide and N,N-dimethylacetamide – A volumetric and acoustic study
PublikacjaDensities and sound velocities at temperatures (298.15, 303.15, 308.15, 313.15 and 318.15) K of magnesium(II), calcium(II) and strontium(II) rifluoromethanesulfonates (triflates), as well as barium(II) perchloratein N,N-dimethylformamide (dmf) and N,N-dimethylacetamide (dma) have been measured over the composition range studied. From these results, apparent molar volumes and apparent molar isentropic compressibilities at infinite...
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Effect of Amino Acids and Sodium Chloride on d-Sorbitol in Aqueous Solutions at Different Temperatures: Volumetric and Acoustic Approach
PublikacjaApparent molar volumes and apparent molar compressibilities for d-sorbitol in (0.05, 0.1, 0.2 and 0.3) mol·kg−1 aqueous solutions of l-alanine, l-cysteine and l-histidine and NaCl have been determined from measurements of solution density at T = (288.15, 298.15, 308.15 and 318.15) K and sound velocity at T = 298.15 K, as a function of the concentration of the sugar alcohol. The data were used to obtain the limiting apparent molar...
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A New Direct-Sequence Spread Spectrum Signal Detection Method for Underwater Acoustic Communications in Shallow-Water Channel
PublikacjaDirect-Sequence Spread Spectrum (DSSS) is one of the modulation and coding techniques used in Underwater Acoustic Communication (UAC) systems for reliable data transmision even at low signal levels. However, in a shallow water channel, there is a strong multipath propagation which causes a phase fluctuation of the received signal, affecting the performance of the spread-spectrum system. The article presents a differential method...
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Desulfurization of raw naphtha cuts using hybrid systems based on acoustic cavitation and advanced oxidation processes (AOPs)
PublikacjaA combination of dual-frequency acoustic cavitation (acoustic cavitation) and UV assisted advanced oxidation processes (AOPs) reaction system was developed for desulfurization of raw naphtha used to produce aviation fuels. Various types of oxidants in hybrid systems including hydrogen peroxide, acetic acid, acetone, air and ozone were compared. At optimum oxidant to sulfur compounds molar ratio (rox) of 5.0, the hybrid process...
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Assessment of Wide-Sense Stationarity of an Underwater Acoustic Channel Based on a Pseudo-Random Binary Sequence Probe Signal
PublikacjaThe performances of Underwater Acoustic Communication (UAC) systems are strongly related to the specific propagation conditions of the underwater channel. Designing the physical layer of a reliable data transmission system requires a knowledge of channel characteristics in terms of the specific parameters of the stochastic model. The Wide-Sense Stationary Uncorrelated Scattering (WSSUS) assumption simplifies the stochastic description...
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Computer simulations of hearing aid acoustical system performance
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Integrated acoustical-optical system for inventory of hydrotechnical objects
PublikacjaThe knowledge of the location, shape and other characteristics of spatial objects in the coastal areas has a significant impact on the functioning of ports, shipyards, and other waterinfrastructure facilities, both offshore and inland. Therefore, measurements of the underwater part of the waterside zone are taken, which means the bottom of the water and other underwater objects (e.g. breakwaters, docks, etc.), and objects above...
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Modeling and Designing Acoustical Conditions of the Interior – Case Study
PublikacjaThe primary aim of this research study was to model acoustic conditions of the Courtyard of the Gdańsk University of Technology Main Building, and then to design a sound reinforcement system for this interior. First, results of measurements of the parameters of the acoustic field are presented. Then, the comparison between measured and predicted values using the ODEON program is shown. Collected data indicate a long reverberation...
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How Machine Learning Contributes to Solve Acoustical Problems
PublikacjaMachine learning is the process of learning functional relationships between measured signals (called percepts in the artificial intelligence literature) and some output of interest. In some cases, we wish to learn very specific relationships from signals such as identifying the language of a speaker (e.g. Zissman, 1996) which has direct applications such as in call center routing or performing a music information retrieval task...
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Influence of the Widespread Use of Corten Plate on the Acoustics of the European Solidarity Centre Building in Gdansk
PublikacjaThis paper describes the relationship between a strong architectural vision that is difficult to balance, and user expectations in terms of acoustics. The focus is on the use of corten steel as the dominant finishing material on façades and interiors to achieve an expressive, symbolic message through program-based design. The architectural premises justifying the adopted solutions are presented, especially the universality and...
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Perception-based data processing in acoustics. Applications to music information retrieval and psychophysiology of hearing.
PublikacjaTematyka książki obejmuje w pierwszej kolejności opis mechanizmów kognitywnych leżących u podstaw percepcji muzyki. Przedstawione zostały również zagadnienia automatycznego rozpoznawania dźwięków instrumentów muzycznych i muzyki, zastosowanie nowych metod z dziedziny sztucznej inteligencji w szeroko rozumianej inżynierii dźwięku oraz komputerowych metod badania słuchu.
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Protochlorophyll complexes with similar steady-state fluorescence characteristics can differ in fluorescence lifetimes. A model study in Triton X-100
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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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Influence of NiO doping on elastic properties of Li2SO4-MgO-P2O5 glass system-Investigation by means of acoustic wave propagation
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