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Wyniki wyszukiwania dla: ACOUSTIC METHODS
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Standing Waves in One-Dimensional Resonator Contaning an Ideal Isothermal Gas Affected by the Constant Mass Force
PublikacjaThe study is devoted to standing acoustic waves in one-dimensional planar resonator which containing an ideal gas. A gas is affected by the constant mass force. Two types of physically justified boundary conditions are considered: zero velocity or zero excess pressure at both boundaries. The variety of nodal and antinodal points is determined. The conclusion is that the nodes of pressure and antinodes of velocity do not longer...
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Przegląd metod pomiaru temperatury przewodów linii napowietrznych wysokiego napięcia
PublikacjaW artykule przedstawiono przegląd metod pomiaru temperatury napowietrznych linii wysokiego napięcia stosowanych w celu poprawy niezawodności eksploatacji i w celu wyznaczania dopuszczalnej obciążalności linii. Omówiono system DOL dynamicznej obciążalności linii oraz bezdotykowe metody pomiaru temperatury: pomiar z użyciem pasywnych czujników SAW (ang. Surface acoustic wave sensor), DTS (distributed temperature sensing) z wykorzystaniem...
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Communication Platform for Evaluation of Transmitted Speech Quality
PublikacjaA voice communication system designed and implemented is described. The purpose of the presented platform was to enable a series of experiments related to the quality assessment of algorithms used in the coding and transmitting of speech. The system is equipped with tools for recording signals at each stage of processing, making it possible to subject them to subjective assessments by listening tests or, objective evaluation employing...
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Analiza i ocena smarności olejów w ujęciu energetycznym i działania układu tribologicznego = Analysis and evaluation of oil lubricity from the viewpoint of energy apects and of the tribological system action
PublikacjaBased on measurement results, an interpretation is presented of the tribological system boundary layer action in the form of a four-ball tester friction node. The evaluation was performed of the boundary layer action understood as transfer of energy Ep resulting from loading the tribological system in a determined time t with work Lp, which may lead to breaking the boundary layer. That energy and time are the values unequivocally...
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Sound Field Intensity Measurements and Visualization around the Human Head Model . Rozkłąd natężenia pola akustycznego w komorze bezechowej obecności sztucznej głowy i w przypadku braku jej obecności
PublikacjaThe main goal of this research study was to measure and visualize sound field intensity distribution in and without presence of the human head model. Measurements were performed in the anechoic chamber with the 5 cm grid. Experimental setup consisted of a multitone generator, two loudspeakers, human head model, intensimetric probe, the Cartesian robot applied for precise positioning of the acoustic sensor, and an analyzer. Based...
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The Doppler effect in a bistatic system for determining the position of moving targets
PublikacjaThe article presents the theoretical analysis and the results of numerical calculations of the Doppler effect it occurs in a system designed to determine the position and speed of a moving target. The transmitter is the source of the signal and it emits a sinusoidal, acoustic and continuous wave. Signal reflected off a moving target is received by four hydrophones. Based on the signals, four Doppler shifts are determined and inserted...
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Study of Noise Propagation for Small Vessels
PublikacjaThe paper presents the results of the noise propagation analysis in ship structures tested in a number of AHTS (Anchor Handling Tug Supply) vessels. Statistical Energy Analysis (SEA) based on numerical model developed specially for the purpose of this numerical investigation were conducted. This numerical model enabled the analysis of both the structural elements and the acoustic spaces. For the detailed studies 47 points fixed...
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Source-related Wavefields in Fluids and Dielectrics: A new way of Thinking about Medium Dynamics
PublikacjaAcoustic and electromagnetic wave phenomena may seem to have a proper formal representation in field theory dating from the 19th century, founded on the mathematics of complex functions. This paper shows, however, that when replacing the classical spectrum-domain approach related to the assumption of harmonic timeform of signals, with a time-domain approach imposingnorestrictionastotheclassoftimeevolutionofsourceandfieldsignals,...
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HYDROACOUSTIC NOISE MEASUREMENTS
PublikacjaThe paper deals mainly with investigation of underwater noise that propagation is in shallow water. In this paper has been presented the experimental investigation results concerning the distribution of the sound field pressure generated by moving ships in the shallow water at the small distance from the ship. The main acoustical characteristics describing features of the field are spectrograms in pseudo 3D system – distance and frequency...
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A Comparison of Simplified Two-dimensional Flow Models Exemplified by Water Flow in a Cavern
PublikacjaThe paper shows the results of a comparison of simplified models describing a two-dimensional water flow in the example of a water flow through a straight channel sector with a cavern. The following models were tested: the two-dimensional potential flow model, the Stokes model and the Navier-Stokes model. In order to solve the first two, the boundary element method was employed, whereas to solve the Navier-Stokes equations, the...
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Underwater Navigation System Based on Doppler Shifts of a Continuous Wave
PublikacjaThe paper describes a concept of an underwater navigation system designed to determine the location and speed of its ROVs or divers. Conducted by the Department of Marine Electronic Systems at the Gdansk University of Technology for several years, research has focused on navigation systems which determine positions on the basis of Doppler shifts of echo signals reflected from a moving object. This article presents a different version...
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Optimizing of target detection and tracking processes realized on consoles of passive sonar with linear towed antenna
PublikacjaThe long-range passive towed sonar was first modernised a few years ago. Building on operator experience over that period, a concept was developed of optimising the tasks performed by sonar operators, and improving forms of imaging to inform about object detection and support object tracking. The concept was implemented and successfully tested during ships’ manoeuvres. The optimisation of operator tasks was designed to keep listening...
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MSIS sonar image segmentation method based on underwater viewshed analysis and high-density seabed model
PublikacjaHigh resolution images of Mechanically Scanned Imaging Sonars can bring detailed representation of underwater area if favorable conditions for acoustic signal to propagate are provided. However to properly asses underwater situation based solely on such data can be challenging for less than proficient interpreter. In this paper we propose a method to enhance interpretative potential of MSIS image by dividing it in to subareas depending...
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Receiver of Doppler multistatic system for moving target detection and tracking
PublikacjaThe article presents a method for solving major structural problems that occur in the receiver used in the multistatic Doppler system, aimed at determination of the trajectory and velocity of a moving target. In the system two transmitters emit acoustic continuous sinusoidal waves at different frequencies. The signals, scattered from a moving target are received by four hydrophones. Beside of the echoes, much larger signals coming...
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Transmission parameters of underwater communication channels
PublikacjaThe underwater environment is tough and demanding as a communication channel for ultrasonic signals. The channel transmission characteristics in marine and inland waters depend much on local bathymetry and changing weather conditions. The architecture and performance of a reliable underwater acoustic communication (UAC) system should allow real-time adaptation of its transmission parameters to a large variety of possible channel...
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The instantaneous frequency rate spectogram
PublikacjaAn accelerogram of the instantaneous phase of signal components referred to as an instantaneous frequency rate spectrogram (IFRS) is presented as a joint time-frequency distribution. The distribution is directly obtained by processing the short-time Fourier transform (STFT) locally. A novel approach to amplitude demodulation based upon the reassignment method is introduced as a useful by-product. Additionally, an estimator of energy...
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Vortex flow caused by periodic and aperiodic sound in a relaxing maxwell fluid
PublikacjaThis paper concerns the description of vortex flow generated by periodic and aperiodic sound in relaxing Maxwell fluid. The analysis is based on governing equation of vorticity mode, which is a result of decomposition of the hydrodynamic equations for fluid flow with relaxation and thermal conductivity into acoustical and non-acoustical parts. The equation governing vorticity mode uses only instantaneous, not averaged over sound...
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Implementation of DIFAR Processing in ASW Dipping Sonar
PublikacjaThis paper presents the implementation of the signal processing algorithm used by buoy DIFAR (Directional Frequency Analysis and Recording), that is fully operational on Polish Navy anti-submarine warfare (ASW) helicopters and ships, applied to dipping sonars for detection and tracking of submarines. The development of the DSP algorithms was a part of the modernization of sonars conducted at the Gdansk University of Technology....
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Instantaneous Heating and Cooling Caused by Periodic or Aperiodic Sound of Any Characteristic Duration in a Gas with Vibrational Relaxation
PublikacjaThermodynamic relaxation of internal degrees of a molecule's freedom in a gas occurs with some characteristic time. This makes wave processes in a gas behave differently depending on the ratio of characteristic duration of perturbations and the relaxation time. In particular, generation of the secondary non-wave modes by intense sound in a nonlinear flow dependens on frequency. These kinds of interaction are considered in this...
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Finite Element Method Applied in Electromagnetic NDTE: - A Review
PublikacjaThe paper contains an original comprehensive review of finite element analysis (FEA) applied by researchers to calibrate and improve existing and developing electromagnetic non-destructive testing and evaluation techniques, including but not limited to magnetic flux leakage (MFL), eddy current testing, electromagnetic-acoustic transducers (EMATs). Premium is put on the detection and modelling of magnetic field, as the vast majority...
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Method for the correlation coefficient estimation of the bottom echo signal in the shallow water application using interferometric echo sounder
PublikacjaThe article presents a new method for the assessment of bottom echo correlation coefficient in the presence of multiple echoes. Bottom correlation coefficient is a parameter that characterizes spatial properties of echo signal. Large variability of the bottom shape or properties (for example caused by the presence of bottom objects) and the presence of the acoustic shadow strongly influence the value of the correlation coefficient....
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Sounding of Layered Marine Bottom - Model Investigations
PublikacjaThe necessary actions connected with interpretations of examining of physical properties of sea bottom structure is developing of proper procedure of modeling of the layered structure. The implementation of the acoustic waves for the determination of seabed stratification requires a precise diagnosis of the topic from both the theoretical and practical side. Little differences between the parameters of sediments, as well as irregular...
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Can Historic Interiors with Large Cubature be Turned Acoustically Correct?
PublikacjaHistoric interiors with large cubature, such as reception, theatrical, and concert halls, need to be renovated periodically if they are to be preserved as cultural heritage for future generations. In such cases it is necessary to maintain appropriate balance between requirements imposed by heritage conservation authorities office which are usually being given a higher priority, applicable safety regulations, and the comfort of...
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The estimation of fish lenght distribution from its acoustical measures
PublikacjaThe paper concerns the problem of estimating fish length PDF from its target strength PDF obtained from acoustic surveys. It has been shown that the target strength of single fish can be treated in the first approximation as a finction of two variables: one, which depends on fish size and the other, which depends on its angular orientation (aspect). Extending this simplified relationship to the case of fish populations allows to...
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In uence of Low-Level Features Extracted from Rhythmic and Harmonic Sections on Music Genre Classi cation
PublikacjaWe present a comprehensive evaluation of the infuence of 'harmonic' and rhythmic sections contained in an audio file on automatic music genre classi cation. The study is performed using the ISMIS database composed of music files, which are represented by vectors of acoustic parameters describing low-level music features. Non-negative Matrix Factorization serves for blind separation of instrument components. Rhythmic components...
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Performance of Noise Map Service Working in Cloud Computing Environment
PublikacjaIn the paper a noise map service designated for the user interested in environmental noise subject is presented. It is based on cloud computing. Noise prediction algorithm and source model, developed for creating acoustic maps, are working in cloud computing environment. In the study issues related to noise modeling of sound propagation in urban spaces are discussed with a special focus on road noise. Examples of results obtained...
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Method of managing drill cuttings from shale gas formations
PublikacjaProposed management method of drill cuttings involves recycling for the expanded clay production. A theoretical presentation of the possibility, choosing planning path based on similarity between the materials used in the manufacture of expanded clay and oily cuttings. Application for the main stages of manufacture of expanded clay production of drill cuttings from shale gas extraction. Introduced into circulation solid waste partly...
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Impact of the glazed roof on acoustics of historic interiors
PublikacjaThe paper discusses the adverse acoustic phenomena occurring in the semi-open interiors (courtyards, yards) covered with a glass roof. Particularly negative is the rever-beration noise, which leads to the degradation of the utility functions of the resulting spaces. It involves the drastically reducing the intelligibility of speech, loss of natural sounding of music, problems with the sound system, as well as disturbances in the...
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Effect of pine impregnation and feed speed on sound level and cutting power in wood sawing
PublikacjaThe sound levels along with the cutting power registered during the sawing process of the impregnated and non-impregnated pine wood at two feed speeds are shown and compared in this paper. Statistically significant differences in the acoustic signals occurred at the lower feed rate. The differences became smaller with an increase in the feed speed. In contrast to the sound signal, the differences...
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Tire/Road Noise On Poroelastic Road Surfaces - Results Of Laboratory Measurements
PublikacjaTire/road noise is the most important part of traffic noise for medium and high speed driving both in the case of passenger cars and trucks. The potential to make modification of tires that significantly reduce tire/road noise in nearly over, at least for conventional tires so the only promising action is to improve road pavements. One of the innovative solutions is poroelastic road pavement (PERS) that reduces airflow related...
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Merging extremum seeking and self-optimizing narrowband interference canceller - overdetermined case
PublikacjaActive cancellation systems rely on destructive interference to achieve rejection of unwanted disturbances entering the system of interest. Typical practical applications of this method employ a simple single input, single output arrangement. However, when a spatial wavefield (e.g. acoustic noise or vibration) needs to be controlled, multichannel active cancellation systems arise naturally. Among these, the so-called overdetermined...
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Cross-Lingual Knowledge Distillation via Flow-Based Voice Conversion for Robust Polyglot Text-to-Speech
PublikacjaIn this work, we introduce a framework for cross-lingual speech synthesis, which involves an upstream Voice Conversion (VC) model and a downstream Text-To-Speech (TTS) model. The proposed framework consists of 4 stages. In the first two stages, we use a VC model to convert utterances in the target locale to the voice of the target speaker. In the third stage, the converted data is combined with the linguistic features and durations...
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The development of an underwater telephone for digital communication purposes
PublikacjaThe underwater telephone HTL-10 has been designed to provide voice and data communication between helicopter and submarines using acoustic waves. It works in a half-duplex mode and uses analogue power-efficient modulation in the form of a single side-band, suppressed carrier, in a wide range of frequencies. It generates the transmitted signal, and processes the received signals. It is implemented with the use of digital signal...
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Global Complex Roots and Poles Finding Algorithm in C × R Domain
PublikacjaAn algorithm to find the roots and poles of a complex function depending on two arguments (one complex and one real) is proposed. Such problems are common in many fields of science for instance in electromagnetism, acoustics, stability analyses, spectroscopy, optics, and elementary particle physics. The proposed technique belongs to the class of global algorithms, gives a full picture of solutions in a fixed region ⊂ C × R and...
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An Attempt to Create Speech Synthesis Model That Retains Lombard Effect Characteristics
PublikacjaThe speech with the Lombard effect has been extensively studied in the context of speech recognition or speech enhancement. However, few studies have investigated the Lombard effect in the context of speech synthesis. The aim of this paper is to create a mathematical model that allows for retaining the Lombard effect. These models could be used as a basis of a formant speech synthesizer. The proposed models are based on dividing...
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Backscattering properties of southern Baltic herring
PublikacjaReliable TS(L) relationship is required to improve acoustic algorithms of abundanceestimation of Baltic herring. The relationships, empirically obtained in different parts of theBaltic Sea, produce up to 8 dB – difference in the herring TS. In order to develop an accurateTS(L) relationship, it is important to analyze factors controlling the TS variability. Thepossible impact of the regional difference...
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Computer vision techniques applied for reconstruction of seafloor 3D images from side scan and synthetic aperture sonars data
PublikacjaThe Side Scan Sonar and Synthetic Aperture Sonar are well known echo signal processing technologies that produce 2D images of the seafloor. Both systems combines a number of acoustic pings to form a high resolution image of seafloor. It was shown in numerous papers that 2D images acquired by such systems can be transformed into 3D models of seafloor surface by algorithmic approach using intensity information, contained in a grayscaled...
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Self-optimizing narrowband interference canceller - can reference signal help?
PublikacjaSONIC (Self-Optimizing Narrowband Interference Canceller) is an acronym of the recently proposed active noise control algorithm with interesting adaptivity and robustness properties. SONIC is a purely feedback controller, capable of rejecting nonstationary sinusoidal disturbances (with time-varying amplitudes and/or frequencies) in the presence of plant (secondary path) uncertainties. We show that even though SONIC can work reliably...
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Modelling and Measurement of Folk Guitar: Truss Rod and Strings in Numerical Analysis of Tone
PublikacjaThe study makes an attempt to model a complete vibrating guitar including its non-linear features, specifically the tension-compression of truss rod and tension of strings. The purpose of such a model is to examine the influence of design parameters on tone. Most experimental studies are flawed by uncertainties introduced by materials and assembly of an instrument. Since numerical modelling of instruments allows for deterministic...
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Do Leonardo da Vinci’s drawings, room acoustics and radio astronomy have anything in common?
PublikacjaAfter introducing Leonardo da Vinci’s (LdV) predecessors in the field of light propagation research, his drawings on the topic of reflecting light by a spherical mirror are analysed. The discovery of LdV is presented, according to which, at an infinitely distant source of rays, a small fragment of the canopy is enough to generate a focus, while the rest of the mirror forms a caustic for which LdV did not indicate an application....
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Using wavelet techniques for multibeam sonar bathymetry data compression
PublikacjaMultibeam sonars are widely used in applications like high resolution bathymetry measurements or underwater object imaging. One of the significant problems in multibeam sensing of the marine environment is large amount of data which must be transmitted from the sonar processing unit to an operator station using a limited bit rate channel. For instance, such a situation would be in the case when the multibeam sonar was mounted on...
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Hybrid SONIC: joint feedforward–feedback narrowband interference canceler
PublikacjaSONIC (self-optimizing narrowband interference canceler) is an acronym of a recently proposed active noise control algorithm with interesting adaptivity and robustness properties. SONIC is a purely feedback controller, capable of rejecting nonstationary sinusoidal disturbances (with time-varying amplitude and/or frequency) in the presence of plant (secondary path) uncertainty. We show that although SONIC can work reliably without...
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Separability Assessment of Selected Types of Vehicle-Associated Noise
PublikacjaMusic Information Retrieval (MIR) area as well as development of speech and environmental information recognition techniques brought various tools in-tended for recognizing low-level features of acoustic signals based on a set of calculated parameters. In this study, the MIRtoolbox MATLAB tool, designed for music parameter extraction, is used to obtain a vector of parameters to check whether they are suitable for separation of...
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On the compression of multibeam sonar raw bathymetry data
PublikacjaMultibeam sonars are widely used in applications like high resolution bathymetry measurements or underwater object imaging. One of the significant problems in multibeam sensing of the marine environment is large amount of data which must be transmitted from the sonar processing unit to an operator station using a limited bit rate channel. For instance, such a situation would be in the case when the multibeam sonar was mounted on...
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Reactive Sintering of Ground Tire Rubber (GTR) Modified by a Trans-Polyoctenamer Rubber and Curing Additives
PublikacjaThe proposed method of ground tire rubber (GTR) utilization involves the application of trans-polyoctenamer rubber (TOR), a commercially available waste rubber modifier. The idea was to investigate the influence of various curing additives (sulfur, N-cyclohexyl-2-benzothiazole sulfenamide (CBS), dibenzothiazole disulfide (MBTS) and di-(2-ethyl)hexylphosphorylpolysulfide (SDT)) on curing characteristics, physico-mechanical, thermal,...
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Understanding the interactions between protein stabilizers and the peptide bond through the analysis of the volumetric and compressibility properties for the model systems
PublikacjaThis work confirms our earlier supposition, that volumetric and acoustic parameters for simple model proposed by us are directly related to stabilizing/destabilizing effect of osmolytes on proteins structure. The apparent molar volumes, V and the apparent molar isentropic compressions, KS,, of glycine and N,N,N –trimethylglycine (betaine) were determined from densities and speed of sound measurements in aqueous solution of N-methylacetamide...
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Investigation of Noise Threats and Their Impact on Hearing in Selected Schools
PublikacjaNoise measurements conducted in selected schools in Gdansk area are presented in this paper. The main aim of this research was to determine noise threats at schools. Some objective measurements of the acoustic climate were performed employing a noise monitoring station engineered at the Multimedia System Department, Gdansk University of Technology. Simultaneously, subjective noise annoyance examinations were carried out among pupils...
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Investigation of noise threats and their impact on hearing in selected schools - a pilot study.
PublikacjaNoise measurements conducted in selected schools in Gdansk area are presented in this paper. The main aim of this research was to determine noise threats at schools. Some objective measurements of the acoustic climate were performed employing a noise monitoring station engineered at the Multimedia System Department, Gdansk University of Technology. Simultaneously, subjective noise annoyance examinations were carried out among pupils...
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Effective degradation of sulfide ions and organic sulfides in cavitation-based Advanced Oxidation Processes (AOPs)
PublikacjaThe paper presents the results of investigations on the effectiveness and reaction rate constants of the oxidation of sulfide ions and organic sulfides in real industrial effluents from the production of bitumens (2000 mg S2- L-1) using hydrodynamic and acoustic cavitation. The content of the effluents was analysed in terms carbon disulfide, dimethyl sulfide, and di-tert-butyl disulfide concentration. A possibility of complete...
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An in-depth look at the tire rubber hardness influence on tire/road noise measurements
PublikacjaWhen assessing the acoustic quality of a road pavement with the close-proximity (CPX) or the on-board sound intensity (OBSI) method, the rubber hardness of the reference tire substantially affects the measurement. Practical experience shows that measurement tires can get significantly harder within a single measurement season. This is why one would like to normalize measurements to a reference rubber hardness. The recently published...