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EN
The acquisition parameters and methodology of seismic data processing for high-resolution seismic imaging viewed through relative amplitude preservation are presented. An example of the obtaining of high-quality, shallow seismic data with a variable end-on spread is shown. The source used for the project is an accelerated weight drop. The study area lies within the mine waste disposal area, near Rudna village (Fore-Sudetic Monocline, WS Poland), and results are given for a 2D experimental profile. The aim of the project was to design optimal acquisition and processing parameters for the detailed recognition of Tertiary deposits. The proposed acquisition parameters are a compromise between time, cost and results. High-resolution seismic imaging enables the determining of layers within the range of thicknesses between 5 and 15 m, while the maximal depth of imaging reaches 400 m.
EN
Impulse noise is particularly hazardous to the hearing of exposed individuals. In many real-life scenarios, the only protective measure used to reduce the level of impulse noise is hearing protectors. These scenarios include firing ranges. Aside from hearing protectors, shooters use personal safety spectacles. The purpose of this paper was to determine the effect of the simultaneous use of earmuffs and safety spectacles on the sound attenuation of earmuffs during exposure to impact noise. The research was completed with the MIRE method and included the determination of sound attenuation changes in five different models of earmuffs, used simultaneously with three different models of safety spectacles and prescription glasses. The impulse noise source used was a starting pistol, which generated C-weighted peak sound pressure level at a mean of 136.7 dB. The tests demonstrated that the simultaneous use of safety spectacles and earmuffs reduces the impulse noise attenuation of the earmuffs by up to 9 dB. Such sound attenuation changes occurred during simultaneous use of earmuffs with safety spectacles, which feature temples with a rectangular cross-section. The tests also demonstrated that the effect of prescription glasses on sound attenuation was unusually high; prescription glasses reduced the impulse sound attenuation of earmuffs by as much as 18 dB.
PL
Hałas impulsowy jest szczególnie niebezpieczny dla słuchu osób na niego eksponowanych. W wielu sytuacjach jedynym środkiem ograniczania hałasu impulsowego są ochronniki słuchu. Taka sytuacja występuje na przykład na strzelnicach. Poza ochronnikami słuchu strzelcy również często korzystają z indywidualnych ochron oczu. Celem przedstawionych badań było określenie jak jednoczesne stosowanie nauszników przeciwhałasowych i okularów wpływa na zmianę tłumienia nauszników w sytuacji występowania hałasu impulsowego. Badania zostały przeprowadzone z wykorzystaniem metody MIRE i obejmowały wyznaczenie zmian tłumienia dźwięku pięciu modeli nauszników przeciwhałasowych stosowanych jednocześnie z trzema modelami okularów ochronnych oraz okularami korekcyjnymi. Źródłem hałasu impulsowego był pistolet startowy, który generował dźwięk o szczytowym poziomie dźwięku C wynoszącym średnio 136,7 dB. Przeprowadzone badania wykazały, że jednoczesne używanie okularów ochronnych i nauszników obniża tłumienie hałasu impulsowego wnoszone przez nauszniki maksymalnie do 9 dB. Takie zmiany występowały podczas jednoczesnego stosowania nauszników i okularów charakteryzujących się zausznikami o prostokątnym przekroju. Badania także wykazały wyjątkowo duży wpływ okularów korekcyjnych na tłumienie nauszników, które spowodowały pogorszenie tłumienia hałasu impulsowego wnoszonego przez nauszniki nawet o 18 dB.
EN
Time-frequency peak filtering (TFPF) is an effective tool for the removal of random noise and can be used to process seismic data with a low signal-to-noise ratio. A crucial aspect of this algorithm is the choice of window length (WL) of the time-frequency distribution. Whereas a fixed WL cannot simultaneously preserve signal and attenuate noise, timevarying WLs can achieve this goal. We propose a new method, L-DVV (delay vector variance), which successfully processes non-stationary signals by using the surrogate to measure the non-linearity of a time series. This method is sensitive to random noise and can accurately recover seismic signal masked by noise. Since the linearity criterion also meets the unbiased estimation criterion of the TFPF algorithm, the L-DVV method can be used for time-varying WL TFPF processing. Analysis of synthetic and real seismic data shows that the time-varying WL TFPF algorithm is effective at removing noise and recovering seismic signal.
EN
In this paper, a novel data denoising method is proposed for seismic exploration with a vibrator which produces a chirp-like signal. The method is based on fractional wavelet transform (FRWT), which is similar to the fractional Fourier transform (FRFT). It can represent signals in the fractional domain, and has the advantages of multi-resolution analysis as the wavelet transform (WT). The fractional wavelet transform can process the reflective chirp signal as pulse seismic signal and decompose it into multi-resolution domain to denoise. Compared with other methods, FRWT can offer wavelet transform for signal analysis in the timefractional- frequency plane which is suitable for processing vibratory seismic data. It can not only achieve better denoising performance, but also improve the quality and continuity of the reflection syncphase axis.
EN
The impulse noise is agent harmful to health not only in the case of shots from firearms and the explosions of explosive materials. This kind of noise is also present in many workplaces in the industry. The paper presents the results of noise parameters measurements in workplaces where four different die forging hammers were used. The measured values of the C-weighted peak sound pressure level, the A-weighted maximum sound pressure level and A-weighted noise exposure level normalized to an 8 h working day (daily noise exposure level) exceeded the exposure limit values. For example, the highest measured value of the C-weighted peak sound pressure level was 148.9 dB. In this study possibility of the protection of hearing with the use of earplugs or earmuffs was assessed. The measurement method for the measurements of noise parameters under hearing protection devices using an acoustical test fixture instead of testing with the participation of subjects was used. The results of these measurements allows for assessment which of two tested earplugs and two tested earmuffs sufficiently protect hearing of workers in workplaces where forging hammers are used.
EN
Determining the effectiveness of impulse noise attenuation with hearing protection devices (HPDs) is an important part of their selection. Measuring impulse noise parameters under an HPD would involve exposing subjects to impulses with a high peak sound pressure level. This paper presents a computational method of determining impulse noise parameters under the cups of earmuffs. Calculations are done using the transfer function of earmuffs, determined with Shaw's electrical equivalent of an HPD, taking into account the design parameters of earmuffs. The developed method was used for calculations in the presence of impulse noise generated by gunshots. To verify the computational method, the results of these calculations were compared with the results of measurements.
PL
Artykuł poświęcony zagadnieniu tłumienia hałasu w systemach wentylacyjnych i klimatyzacyjnych, w których podstawowym źródłem hałasu są wentylatory i ich elementy napędowe. W pierwszej części artykułu omówiono zagadnienie jego tłumienia w odniesieniu do elementów instalacji: przewodów wentylacyjnych, łuków i kolan, skokowej zmiany przekroju oraz kratek wentylacyjnych. W drugiej jego części przedstawiono ogólny podział i charakterystykę stosowanych tłumików dźwięku
EN
The paper deals with the problem of noise reduction in air conditionig and ventilating systems, where the main source of noise are ventilators and their propulsion devices. In the first part the problem of noise reduction in elements of ventilating ducts is discussed. Different types of noise dampers are characterized in the second part of the paper
EN
In the case of biomedical signals with a quasi-cyclic character, such as electrocardiographic signals, the high resolution electrocardiograms or electrical potentials recorded from the nervous system of patients (estimating brain activity evoked by a known stimulus), as a method of averaging in the time domain may be used for noise attenuation. In this paper there is presented input data partitioning applied to a few different methods of weighted averaging. This procedure usually leads to improve the quality of the resulting averaged signal, especially when fuzzy partitioning is used. Below it is presented the computational study of weighted averaging with traditional (sharp) and fuzzy partition of the input data in the presence of non-stationary noise. The performance of presented methods is experimentally evaluated for analytical signal of EN 60601-2-51 (2003), namely ANE20000 ECG record.
EN
In the paper the analysis of the effectiveness of multiples and random noise attenuation using Karhunen-Loeve (K-L) transform is presented. The K-L transform is realized with application the process Eigenimage Filter in seismic data processing system ProMAX. The basic part of the paper is directed to the analysis of multiples attenuation by means of the K-L transform applied to field data. In the analysis the common shot point gathers (seismic records) were used as well as the traces of the CDP gathers. In the case of CDP gathers the main attention was paid on the multiple attenuation in the averaged CDP gathers (supergathers) prepared for the interactive velocity analysis. The influence of the K-L filter parameters was defined on the effectiveness of multiples removing from the velocity analysis wave images. Finally the effectiveness of the K-L filter was estimated in improving the coherent to random signals ratio on the seismic records.
PL
W prezentowanej pracy przedstawiono analizę efektywności tłumienia fal wielokrotnych i szumu przypadkowego za pomocą filtracji Karhunena-Loevego (K-L), realizowanej z wykorzystaniem procedury Eigenimage Filter systemu przetwarzania ProMAX. Zasadniczą część pracy poświęcono analizie efektywności tłumienia fal wielokrotnych za pomocą filtracji K-L, zastosowanej do danych polowych. W analizie wykorzystano zarówno trasy kolekcji wspólnego punktu wzbudzenia (rekordy sejsmiczne), jak i trasy kolekcji wspólnego punktu odbicia (kolekcje CDP). W przypadku kolekcji CDP uwagę skoncentrowano na osłabianiu fal wielokrotnych w uśrednionych kolekcjach CDP (superkolekcje CDP), przygotowanych do interaktywnej analizy prędkości. Określono wpływ parametrów filtracji K-L na skuteczność usuwania fal wielokrotnych z obrazu falowego analiz prędkości. W końcowym etapie pracy oceniono skuteczność filtracji K-L w poprawianiu stosunku sygnałów koherentnych do zakłóceń przypadkowych na rekordach sejsmicznych.
10
Content available Attenuation of Noise by Motorcycle Safety Helmets
EN
For workers such as police motorcyclists or couriers, traffic and engine noise reaching the ears is an important factor contributing to the overall condition of their work. This noise can be reduced with motorcycle helmets. In this study, insertion loss of motorcycle helmets was measured with the microphone-in-real-ear technique and sound attenuation with the real-ear-at-threshold method. Results for 3 Nolan helmets show essentially no protection against external noise in the frequency range <250 Hz. In the frequency range >500 Hz, attenuation increases linearly at a rate of 8–9 dB per octave, to ~30 dB at 8 kHz. Lack of attenuation in the low-frequency range may cause annoying effects. In addition, high attenuation in the high-frequency range may decrease intelligibility of speech signals for a rider in a helmet. Attenuation measured in this study does not take into account noise generated by turbulent wind around the helmet. Thus, the measured values of attenuation represent a motorcycle rider’s best conditions of hearing.
12
Content available remote Attenuation of outside noise by shotblasting helmets
EN
Abrasive blasting is a technological process in which forcibly propelling a stream of abrasive material is used to clean or prepare a surface. Among various physical and chemical hazards related to this process a shotblasting operator is exposed to high levels of noise. Regardless of the fact that there are no requirements to measure and report the attenuation of high level of blasting noise, manufacturers often face a question to which extent shotblasting helmets protect the operator from noise. Currently the well developed method for measuring the noise attenuation of shotblasting helmets is neither given in EN 271 standard dealing with the construction of helmets nor in EN 458 series of standards dealing with requirements for hearing protective devices. The purpose of this paper is to present the method of measurements of the noise attenuation provided by the shotblasting helmet.
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