Wyniki wyszukiwania - BazTech

1

Identification of rattle noise sources in the vehicle cabin using an acoustic camera

Warczek Jan

Zeszyty Naukowe. Transport / Politechnika Śląska

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2025

|

z. 126

267--289

EN

Driving comfort in the car cabin depends on the prevailing acoustic climate. The occurrence of various types of intermittent noises is a common phenomenon observed by users of motor vehicles. In the cabins of motor vehicles, a local source of non-stationary noise due to the propagation of sound waves in the air and in the structural structure makes it practically impossible to determine its location organoleptically. The article presents the use of an acoustic camera to locate noise sources. Research was presented in the field of recognizing the location of sources intentionally introduced into the cabin and identifying spontaneous sources caused by operational wear. The obtained results confirmed the usefulness of using an acoustic camera in identifying noise sources, however, the presence of apparent sources may in some cases result in incorrect diagnoses.

2

Hałas lotniczy – podstawy modelowania

Witoś Mirosław, Wachłaczenko Michał, Wajda-Figur Honorata, Kozieł Mariusz Piotr

Journal of KONBiN

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2025

|

Vol. 55, iss.1

29--60

EN

A sustainable approach to aircraft noise requires not only design changes to engines and aircraft, but also improved methods for modelling noise and its propagation through the air. The article continues the authors' holistic view of the problem of aircraft noise, also taking into account data from military aviation. First, the social and health problem of aircraft noise is recalled. Then the theoretical basis in acoustics and modern aviation noise modelling tools are presented, as well as selected research projects carried out in Sweden to assist in the reduction of aircraft noise. In the results of the study, an addendum to the mathematical description of airborne noise propagation and examples are presented. In conclusion, the authors' insights from their research are indicated.

PL

Zrównoważone podejście do hałasu lotniczego wymaga nie tylko zmian konstrukcyjnych silników i samolotów, ale również doskonalenia metod modelowania hałasu i jego propagacji w powietrzu. Artykuł kontynuuje prezentację holistycznego spojrzenia autorów na problem hałasu lotniczego, z uwzględnieniem danych również z lotnictwa wojskowego. Na początku przypomniano problem społeczny i zdrowotny hałasu lotniczego. Następnie przedstawiono podstawy teoretyczne z akustyki i współczesne narzędzia modelowania hałasu lotniczego oraz wybrane projekty badawcze realizowane w Szwecji, mające na celu wspomaganie redukcji hałasu lotniczego. W wynikach badań przedstawiono uzupełnienie opisu matematycznego propagacji hałasu w powietrzu i przykłady. W podsumowaniu wskazano spostrzeżenia autorów z przeprowadzonych badań.

3

Failure Detection of Powertrain Components in Motor Vehicles Using Vibroacoustic Methods

Kriston József Balázs, Jálics Károly

Archives of Acoustics

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2025

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Vol. 50, nr 1

37--45

EN

Although noise and vibration measurements are widespread in the machine diagnostics, they are not usedin the diagnostics of the powertrain of motor vehicles. Our research aims to investigate the possibilities, advan-tages, and drawbacks of using noise and vibration diagnostics performed for motor vehicles. In this paper, weattempt to use vibroacoustic signals from a motor vehicle for diagnostic purposes. Ordinary audible malfunc-tions, for example, misfiring in a passenger car, were artificially created. The differences between the normaland faulty operating conditions were examined to identify evidence of failure in the vibration signal. Primarily,evaluation through Fourier transformation was performed to provide a visual correlation between the fault andthe vibration behavior of the car. Detailed conclusions from the measurements and future research plans arediscussed.

4

The impact of diffuser arrangement in a reverberation room on airborne sound insulation measurements

Mleczko Dominik, Sapieja Kinga

Vibrations in Physical Systems

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2024

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Vol. 35, nr 3

art. no. 2024319

EN

The primary issue in evaluating airborne sound insulation lies in quantifying the sound energy emitted by the barrier. This is typically accomplished by measuring sound pressure levels in sending and receiving rooms and acoustic absorption within the receiving room. When significant fluctuations in sound pressure levels occur within a reverberation room, it indicates the presence of standing waves, necessitating the incorporation of diffusing elements. The paper presents the results of computational modelling calculations for various configurations of diffusing elements in a reverberation room. These diffusers aim to improve the uniformity of the acoustic field in terms of acoustic pressure. Therefore, the focus of the model was on these parameters. The simulation results were verified by conducting acoustic measurements in an actual room. The ultimate goal was to assess the impact of changes in the arrangement of diffusers on the results of sound insulation measurements. As an additional criterion for evaluating the obtained results, the measurement uncertainty of sound insulation with partial uncertainties was adopted.

5

Errors of addition of sound levels of correlated acoustic disturbances

Batko Wojciech, Radziszewski Leszek, Bąkowski Andrzej

Vibrations in Physical Systems

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2024

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Vol. 35, nr 3

art. no. 2024311

EN

The article focuses on formulas for calculating the addition of sound levels when the disturbances of the acoustic pressures that determine them are correlated. Based on the numerical experiments, determine the level of possible errors for different coherence conditions of two noise sources. The performed analyses are associated with the classical calculus of algebra of decibel numbers, as well as its modifications securing the required correctness of its axiomatic. Presents the desirability of its use in the problems of developing measurement data of small values of sound levels. Relates the need for their potential applications to computational issues relating to the study of the sound field in special rooms (e.g., radio and television studios, anechoic chambers, lave caves) and the study of the environment in which these devices or objects are located. Draws attention to their importance in estimating type B uncertainty in controlling the state of acoustic hazards in the environment.

6

Acoustic characterization of the 1.5 Tesla MRI facility in Mobile Imaging Trailer

Arawade Swapnil, Piechowicz Janusz

Vibrations in Physical Systems

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2024

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Vol. 35, nr 2

art. no. 2024219

EN

The Magnetic Resonance (MR) imaging is a very important medical tool for diagnosis of the internal organs of the patient. The major problem associated with MRI is its high noise during operation responsible for anxiety, discomfort and can be harmful for the patient as well as long exposure raises the safety concerns for the operating staffs. This study involves the characterization of the noise in the vicinity of 1.5 Tesla Mobile Imaging Trailer-MRI (MIT-MRI) system, aimed at evaluating the acoustic parameters in the examination room during scanning. The acoustic measurements were carried out using the microphones located inside the MRI examination room for variations of Diffusion Weighted Imaging (DWI) gradient pulse sequences. The sound recordings depicted the waveforms of complex acoustic pulses with high Sound Pressure Level (SPL) spikes of impulse nature. Results revealed equivalent SPL in the MRI examination room exceeds 90 dB(A) and the peak noise was consistently above 101.5 dB(C) and DWI sequence with oscillating gradient (DWI-og) reported peak SPL of 105.9 dB(C). The dominance of the noise is identified in the frequency range of 500-3000 Hz for all scanning sequence. Results indicate that sound levels are high in the mobile scanning facility as compared to the stationary MRI in the hospitals. The noise in the control room and chiller room were also high. Given that these acoustic measurements surpass recommended noise standards, the significance of ear protection is emphasized. These results can be useful in designing the noise reduction strategies to improve the patient comfort and safety.

7

Sustainable acoustics: the impact of AI on acoustics design and noise management

Starowicz Adam, Zieliński Marcin

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2024

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Vol. 27

193--209

EN

The collaboration between artificial intelligence (AI) and acoustics marks a groundbreaking advancement in creating optimal soundscapes across various environments. This article explores the profound impact of AI on reshaping acoustics, transitioning from an art form to a precise science. Through AI-driven techniques, architects and designers can now analyze architectural parameters and materials to achieve ideal sound properties in room acoustics design. Additionally, AI plays a pivotal role in noise reduction and control, mitigating unwanted sounds and enhancing auditory clarity. Its application extends to improving speech intelligibility in noisy environments, particularly in modern workplaces, and facilitating environmental noise monitoring for urban planning and noise pollution mitigation. With numerous case studies highlighting AI’s transformative influence, this article provides valuable insights into future innovations and the potential for AI to revolutionize our sonic surroundings. In essence, AI harnesses computer systems to simulate human intelligence processes, optimizing sound environments and revolutionizing the field of acoustics.

8

Buildings for music as the icons of the Polish cities’ new architectural identity

Białkiewicz Joanna Jadwiga

Przestrzeń i Forma

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2024

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nr 57

9--28

EN

Over the last 20 years, a great number of investments related to cultural institutions can be observed in Poland, among which the houses for music – particularly stand out. The aim of the analysis is to indicate the common features of the mentioned buildings, and those which determine their exceptional architectural quality. These are: contextualism – a creative and symbolic reference to the local history and tradition; the use of innovative technologies; optimal acoustics; expressive interiors. In every case the goal was to create an iconic object and this was achieved thanks to the modern architectural form and the symbolic references to the cities’ history and genius loci.

PL

W ciągu ostatnich 20 lat można zaobserwować w Polsce dużą liczbę inwestycji związanych z instytucjami kultury, wśród których szczególnie wyróżniają się domy dla muzyki. Celem analizy jest wskazanie cech wspólnych opisanych obiektów oraz warunkujących ich wyjątkową jakość architektoniczną. Są to: kontekstualizm, czyli kreatywne i symboliczne nawiązanie do historii i tradycji regionu, kontekstu miejsca i funkcji; zastosowanie nowatorskich materiałów i technologii; optymalna akustyka; ekspresyjne wnętrza. Celem było każdorazowo stworzenie obiektów ikonicznych, medialnych landmarków, i zostało to osiągnięte dzięki wyróżniającej się nowoczesnej formie architektonicznej i nawiązaniu do historii i genius loci miast.

9

Rola i znaczenie dźwięku w ocenie jakości żywności

Marzec Agata

Przemysł Spożywczy

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2024

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T. 78, nr 2

36--41

PL

Cechy tekstury takie jak: kruchość/ chrupkość można kontrolować metodami instrumentalnymi, w tym metodami akustycznymi polegającymi na pomiarze dźwięku wytwarzanego podczas deformacji produktów spożywczych. Dźwięk jest rodzajem sygnału fizycznego, falą sprężystą (akustyczną), wywołującą określone wrażenie słuchowe i może być zarejestrowany za pomocą mikrofonu lub sensora drgań.

EN

Texture features such as crispness/ crunchiness can be controlled using instrumental methods, including acoustic methods that involve measuring the sound produced during deformation of food products. Sound is a type of physical signal, an elastic (acoustic) wave, causing a specific auditory impression and can be registered using a microphone or a vibration sensor.

10

Spectral Analysis of MRI Sound Signal

Arawade Swapnil, Piechowicz Janusz

International Journal of Electronics and Telecommunications

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2024

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Vol. 70, No. 4

839-847

EN

Magnetic Resonance Imaging (MRI) is a very versatile diagnostic tool for non-invasive analysis of human organ functions, without use of ionizing radiations. Loud operating sound is the major challenge associated with the MRI technology, reaching up to 130dB. This paper analyses and compares the spectral properties of acoustic noise produced in the examination room of the mobile imaging trailer based 1.5 Tesla MRI system, during different scanning sequences of image acquisition. The analysis is useful in understanding the dynamic behavior of the sound generated inside the examination room to develop the noise reduction strategy.

11

Preliminary study: mobile phone as a phonocardiographic signal recorder

Łuczyński Michał

International Journal of Electronics and Telecommunications

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2024

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Vol. 70, No. 3

621-626

EN

The aim of this paper is to analyze the possibility of using a mobile phone with a voice recorder function as a phonocardiographic signal recorder. Test measurements were carried out by placing the phone at various points on the chest. For one selected point, measurements were carried out for a group of 120 people, using different models of mobile phones. Data on weight, height and age were collected through a survey. Participants of the study were also asked about diagnosed heart defects and potential problems related to the measurement. Signal quality was assessed using quality parameters. It was checked how the selected methods of signal pre-processing (editing of recordings, filtering) affect the values of quality parameters. The obtained recordings were subjected to automatic signal classification. The result of this work is an extended analysis of the use of mobile phones as electronic stethoscopes and an analysis of the usefulness of signals obtained using this measurement method. The results of these studies are important for the field of medical diagnostics, especially in situations where access to traditional stethoscopes is limited. If mobile phones prove to be effective recorders of phonocardiographic signals, it will open new possibilities in the field of remote heart monitoring and telemedicine. However, it should be noted that further research, including validation and comparison of results obtained with mobile phones with those obtained with traditional stethoscopes, is needed before this technology is introduced into clinical practice.

12

Problematyka hałasu w energetyce

Karczewski Jacek, Kopania Joanna, Gaj Patryk, Wójciak Kamil

Energetyka

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2024

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nr 10

424--427

PL

W artykule omówiono zagadnienia związane z hałasem generowanym w energetyce. Omówiono źródła hałasu związane z wytwarzaniem (generacja konwencjonalna i OZE) i przesyłem energii elektrycznej. Zwrócono uwagą na związane z hałasem czynniki zagrażające zdrowiu ludzi oraz uwarunkowania środowiskowe. Podano przepisy regulujące zagadnienia związane z walką z hałasem oraz zaprezentowano dopuszczalne poziomy hałasu w środowisku, powodowanego przez poszczególne grupy źródeł hałasu. Omówiono środki i sposoby (bierne i aktywne) redukcji hałasu (tłumiki, osłony akustyczne, ATH).

EN

Discussed are here problems relating to the noise generated in the power industry. Described are noise sources connected with generation (conventional and RES) and transmission of the electric energy. Attention is paid to factors related to the noise and threatening human health as well as to the environmental conditions. Given are regulations concerning the issues connceted with noise reduction and presented are admissible in the environment levels of noise caused by various groups of noise sources. Discussed are ways and means (active and passive) of noise reduction (silencers, acoustic shields, ATH).

13

GTM-120 micro gas turbine engine noise identification

Czarnecki Michał Leszek, Lech Aleksandra

Combustion Engines

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2024

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R. 63, nr 4

52--59

EN

Micro gas turbine engines are a popular subject in research activities; most of them consider performance measurements and vibration analysis, which are related to operating running engines. Operating even small-size engines causes potential risk to operator health. The research problem was to identify the acoustic flow field from the front and back of an operating GTM-120 engine. Research was divided into three parts: identify noise at various rotational speeds, identify the acoustic field of the engine, and identify noise levels at additional points. Obtained results identifies noise, from such a small engine, is at a range of 67 to 109 dBC, which is harmful and unpleasant to people that are within a radius of 15 meters from the engine. The final conclusion is that installing a muffler for any size of turbomachinery should be mandatory.

14

Badania wpływu minerałów hunterytu/hydromagnezytu oraz kalcytu pod kątem niepalności i właściwości mechanicznych kompozytów drzewnych

Atay Gül Yilmaz, Loboichenko Valentyna, Wilk-Jakubowski Jacek Łukasz

Cement Wapno Beton

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2024

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R. 29, nr 1

40--53

PL

W pracy zbadano właściwości dodatków mineralnych w kompozytach drzewnych, które wpływają na palność materiału, a jednocześnie są przyjazne dla środowiska. W artykule poddano analizie wyniki pomiarów kompozytów drewnianych, będących naturalnym materiałem budowlanym wielu domów, a także elementów ich wyposażenia. Jako matrycę zastosowano trociny drzewne. W pracy zbadano wpływ współobecności kalcytu i minerału mieszanego huntyt/hydromagnezyt. Kalcyt zastosowano jako minerał pomocniczy oprócz huntytu/hydromagnezytu, w celu uzyskania lepszego środka zmniejszającego palność zgodnie z normą UL94 i właściwości mechanicznych kompozytu drzewnego, takich jak wytrzymałość na zginanie i moduł sprężystości przy zginaniu. Uzyskane wyniki oceniano w zależności od zawartości składników mineralnych w kompozytach. Wyniki wykazały, że próbka 40S/50H/10C jest optymalna pod względem stosunku modułu sprężystości do niepalności. Materiały ognioodporne można stosować w budownictwie, a także w elektrotechnice, np. w gaśnicach akustycznych [np. do budowy falowodu].

EN

This work examines the characteristics of mineral additives in wood composites that affect the fire retardant properties of the material, and at the same time are environmentally friendly. The paper analyzes the results of measurements for wood composites, which is the natural building material of many houses, as well as elements of their furnishings. Sawdust waste was applied as a matrix. In the paper, a co-presence effect of calcite and huntite/hydromagnesite mineral was investigated. The calcite mineral was used as auxiliary minerals in addition to the huntite/hydromagnesite mineral to obtain a better flame retardant according to the UL94 standard and mechanical properties in the wood composite, such as flexural strength and flexural modulus. The results obtained were measured and evaluated depending on the mineral content of the composites. The results indicated that sample 40S/50H/10C is the most optimal in terms of the ratio of the modulus of flexibility and fire retardant characteristics. Fire retardant materials can be used in the construction industry, as well as in the electrical engineering applications, such as for acoustic fire extinguishers [e.g. for waveguide construction].

15

Improving Sound Insulation in Low Frequencies by a Three-Component Cladding Acoustic Metamaterial Panel

Tan Na, Yan Xiaowei, Liu Bingfei

Archives of Acoustics

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2024

|

Vol. 49, nr 2

267--276

EN

In this paper, a three-component cladding acoustic metamaterial panel with good sound insulation effect in the low-frequency range is proposed. The sound transmission loss of metamaterial panels under different structural configurations and different material parameters is investigated by combining finite element simulation calculations with experimental research. The results show that the closer the center of gravity of the scatterer is to the substrate, the better the stability of the resonance unit, the wider the range of effective sound isolation frequencies, and the higher the degree of normalization. The filling rate of the scatterer is maintained at about 0.5 to obtain a better sound insulation effect. At the same time, choosing lower density materials for the substrate and metal materials with high density and high modulus of elasticity for the scatterer can maximally widen the bandgap and allows for low-frequency sound insulation below 600 Hz. This approach improves the low-frequency sound insulation efficiency of acoustic metamaterials. The results provide important explanations and references for a deeper understanding of the sound insulation mechanism and the effects of different parameters on sound insulation.

16

Evaluation of awareness of existence and potential use of strategic noise maps among residents of the Wawer district in Warsaw

Kumorek Dominika Agnieszka

Architectus

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2024

|

Nr 4 (80)

99--108

EN

Noise pollution currently stands as one of the foremost environmental threats. It has a negative impact on both the physical and mental well-being of users inhabiting affected spaces. It results in difficulties in everyday functioning, and with prolonged exposure, even permanent damage to health. The problem intensifies with the number of newly created noise sources and is particularly oppressive in areas where it did not occur until intensive development. Strategic noise maps (SNM) serve as a valuable tool to help in the fight against the constantly spreading noise. They are used to assess the level of noise in the environment and develop effective protection programs against it. Unfortunately, despite widespread availability, an obvious barrier to the full use of strategic noise maps is low public awareness of their existence, content, and potential utility. The article presents an original study aimed at assessing the awareness of residents of the Wawer district of Warsaw about the existence and possibilities of using strategic noise maps. The study used an online survey in which respondents shared their experiences and opinions about strategic noise maps. The survey results clearly showed that residents’ awareness of the existence and concept of strategic noise maps is low. At the same time, awareness of the benefits of using strategic noise maps is quite high. The respondents also listed a number of barriers that they perceive as obstacles to their full use. The findings of the study led to conclusions, proposing solutions that could increase this awareness.

PL

Hałas jest obecnie jednym z największych zagrożeń środowiskowych. Wpływa negatywnie na kondycję fizyczną i psychiczną użytkowników przestrzeni, w której występuje. Skutkuje trudnościami w codziennym funkcjonowaniu, a w przypadku długotrwałej ekspozycji nawet trwałym uszczerbkiem zdrowia. Problem nasila się wraz z liczbą nowo powstałych źródeł hałasu i jest szczególnie uciążliwy na obszarach, na których do czasu intensywnego rozwoju nie występował. W walce z wciąż rozprzestrzeniającym się hałasem pomóc mają strategiczne mapy hałasu (SMH) służące ocenie poziomu hałasu w środowisku i opracowaniu skutecznych programów ochrony przed nim. Niestety mimo powszechnej dostępności ewidentną barierą w pełnym wykorzystaniu SMH jest niska świadomość społeczeństwa na temat ich istnienia, zawartości i potencjału w walce z hałasem. W artykule zaprezentowano autorskie badanie, którego celem była ocena świadomości mieszkańców warszawskiej dzielnicy Wawer na temat istnienia i możliwości wykorzystania SMH. W badaniu posłużono się ankietą internetową: respondenci podzielili się w takiej formie swoimi doświadczeniami i opiniami na temat SMH. Na podstawie wyników badania jasno wykazano, że świadomość mieszkańców zarówno na temat istnienia, jak i samego pojęcia strategicznych map hałasu jest niska. Jednocześnie świadomość korzyści płynących z wykorzystania SMH jest dosyć wysoka. Ankietowani wymienili także wiele barier stanowiących dla nich przeszkodę w pełnym wykorzystaniu SMH. Uzyskane wyniki posłużyły do sformułowania wniosków w postaci propozycji rozwiązań mogących posłużyć zwiększeniu świadomości w rozpatrywanym zagadnieniu.

17

Architektura teatru dźwiękiem malowana

Telatycka Anna

Zeszyty Naukowe Politechniki Poznańskiej. Architektura, Urbanistyka, Architektura Wnętrz

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2023

|

Z. 17

437--453

PL

Postrzeganie dźwięku może następować na dwóch płaszczyznach – wzrokowej i słuchowej. Oba te wymiary przenikają się wzajemnie. Poprzez tworzenie geometrycznych wzorów dźwięki kreują materię. Cymatyka to nauka, dzięki której możemy zobaczyć kształty wytworzone przez konkretne częstotliwości dźwięku. Wibracje dźwiękowe zagęszczają materię, tworząc rozmaite wzory. Kształty struktur fizycznych również wytwarzają dźwięki (wibracje) zazwyczaj w postaci infradźwięków niesłyszalnych dla ludzkiego ucha. W architekturze można odkryć zależności z figurami powstałymi podczas oddziaływania dźwięku na materię. Każdy obiekt może być generatorem bądź wzmacniaczem energii fal dźwiękowych. Architektoniczne kształty mogą odnosić się do figur Chladniego. Figury te odzwierciedlają miejsca, gdzie występują węzły fali stojącej. Kształt widowni sali widowiskowej (teatralnej) jest ustalany na etapie projektowania architektonicznego. Poprawne rozmieszczenie foteli oraz przejść między nimi na płaszczyźnie widowni może być ściśle związane z jej kształtem i wymiarami. Płaszczyzna ta, drgając, wymusza rozmieszczenie przejść w miejscach, gdzie występują węzły ciśnienia akustycznego, natomiast foteli w miejscach strzałek ciśnienia akustycznego. Jest to nowe podejście do kształtowania architektury wnętrz dla widowni sal widowiskowych.

EN

Sound perception can occur on two levels – visual and auditory. Both of these dimensions interpenetrate each other. By creating geometric patterns, sounds create matter. Cymatics is the science that allows us to see the shapes created by specific sound frequencies. Sound vibrations compact matter, creating various patterns. The shapes of physical structures also produce sounds (vibrations), usually in the form of infrasound that is inaudible to the human ear. In architecture, you can discover relationships with figures created when sound interacts with matter. Any object can be a generator or amplifier of sound wave energy. The architectural shapes may refer to Chladni’s figures. These figures reflect the places where the nodes of the standing wave occur. The shape of the audience of the auditorium (theater) is determined at the architectural design stage. The correct arrangement of seats and transitions between them in the audience area may be closely related to its shape and dimensions. This plane, vibrating, forces the arrangement of transitions in places where there are sound pressure nodes, and seats in places of maximum sound pressure level. This is a new approach to shaping interior architecture for the audience of auditoriums.

18

Determination of rail vehicle speed with acoustic signal processed using continuous wavelet transform

Mokrzan Daniel, Nowakowski Tomasz, Szymański Grzegorz M.

Vibrations in Physical Systems

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2023

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Vol. 34, nr 2

art. no. 2023223

EN

The paper presents the course of research and analysis on the possibility of using time-frequency methods of acoustic signal processing to determine the speed of moving rail vehicles. An experiment was conducted in the form of a trackside pass-by test of the acoustic pressure emitted by passing trams representing the rolling stock of the Municipal Transport Company in Poznan. The recorded signal was then processed using the Continuous Wavelet Transform (CWT), resulting in a scalogram that is a variation of the time-frequency characteristics. This made it possible to identify in the signal the travel time of individual bogies and their wheelsets, as well as the most sensitive value of the scale parameter. The waveform of the scalogram fragment for the selected value of the scale parameter was processed using the RMS envelope, and then the peak values were identified. Juxtaposing the obtained results with the knowledge of the structural dimensions of the tested vehicle, it was possible to determine its moving speed. To validate the results of the experiment, photocells located on both sides of the measurement track were used, which generated voltage when the test vehicle passed between them, allowing the determination of its average moving speed. The result of the study was the formulation of a method that can be used to determine the speed of a vehicle based on the time elapsed between the identification in the signal of the components corresponding to the passage of successive sets of wheels.

19

Scattering problems in 2D space within the Rayleigh regime

Sikora Jan

Przegląd Elektrotechniczny

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2023

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R. 99, nr 2

173--177

EN

In this paper, the application of the classic method of boundary elements to analyse the scattering problems of acoustic waves by a rigid object with a circular cross-section in 2D space is presented. The analysis is presented on the example of a flat wave falling on an object along the x-axis positive direction. The accuracy of the solution for two different cases meeting the Rayleigh regime was analysed. The criteria that must be met in order to expect a reliable solution are provided.

PL

W pracy przedstawiono zastosowanie klasycznej metody elementów brzegowych do analizy problemów rozpraszania fal akustycznych przez sztywny obiekt o przekroju kołowym w przestrzeni 2D. Analizę przedstawiono na przykładzie fali płaskiej padającej na obiekt zgodny z dodatnim kierunkiem osi x. Przeanalizowano dokładność rozwiązania dla dwóch różnych przypadków spełniających wymagania reżimu Rayleigh’a. Podano kryteria jakie muszą być spełnione, aby można było oczekiwać wiarygodnego rozwiązania.

20

Rola izolacji technicznych w zapewnieniu standardu akustycznego

Ryńska Joanna

Izolacje

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2023

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T. 28, nr 11/12

96--98

PL

Izolacje techniczne często omawiane są przede wszystkim pod kątem parametrów cieplnych. Warto jednak pamiętać także o ich innych funkcjach, np. o izolowaniu akustycznym. Własności akustyczne instalacji HVAC czy sanitarnych zyskują coraz większe znaczenie, gdy mowa o standardzie budynków albo poszczególnych lokali w kontekście odpowiedniego komfortu czy rosnących wymagań użytkowników.