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Wyświetlanie 1-8 z 8
Tytuł:
Noise emission from various shape rods at low-moderate Reynolds number
Autorzy:
Kopania, Joanna Maria
Bogusławski, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/2146658.pdf
Data publikacji:
2021
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
noise
circular square rods
u-shape beam
sound pressure level
hałas
pręt kołowy
pręt kwadratowy
belka w kształcie litery U
poziom ciśnienia akustycznego
Opis:
Aeroacoustic source localization is an important experimental tool and the first step to know the mechanism of noise generation. The flow around the various shape of rods is one of the major aeroacoustic noise source mechanism. Such rods represent simple models for technical applications like part of the landing gear of planes, train pantographs, antennas, vehicles part, ventilation system or bridge. The purpose of this paper is to clarify the influence of the rod shape in the noise generation mechanism in a low-moderate Reynolds number. In this work, the situation when various shape rods are in the area of laminar-turbulent flow was analyzed. The measurements were carried out for single circular, square, c-shape rods to study the noise effect depended on the Reynolds number. The measurements were performed on the specially constructed test stand with the outlet to the anechoic room. The 1/3 SPL differential spectrum as 2-D noise maps were obtained for studied rods. The acoustic differences between circular, square and U-beam rods were observed.
Źródło:
Vibrations in Physical Systems; 2021, 32, 2; art. no. 2021202
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of sound absorbing properties of composite made of recycling materials
Autorzy:
Gaj, Patryk
Kopania, Joanna
Wójciak, Kamil
Bogusławski, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/128049.pdf
Data publikacji:
2019
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
sound absorbing materials
recycling
sound absorption coefficient
composite materials
materiały dźwiękochłonne
recykling
współczynnik pochłaniania dźwięku
materiały kompozytowe
Opis:
In modern world we are searching methods to reuse most of industrial disposals produced during manufacturing. Some kinds of materials, like scraps from acoustic foam, however are not so easily utilized using recycling methods for its primary usage. Disposals produced during the manufacturing process can be compressed and reused as sound absorbing material. The purpose of this article is to examine sound absorbing properties of material made of acoustic foam disposals and compare it with sound protection materials, which are commonly used. Sound absorbing damping were tested using Kundt’s tube and reverberation room examination method. Tests were carried out according to standard PN-EN ISO 354:2005, for reverberation room examination, and according to Bruel&Kjaer electronic instruments technical manual for Kundt’s tube examination.
Źródło:
Vibrations in Physical Systems; 2019, 30, 1; 1-7
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The impact of the damper blade position on the generated noise and pressure losses in plenum box with swirl diffusers
Autorzy:
Wójciak, Kamil
Gaj, Patryk
Kopania, Joanna
Bogusławski, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/127800.pdf
Data publikacji:
2019
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
HVAC
noise emission
sound power level
pressure loss
optimization
emisja hałasu
poziom mocy akustycznej
strata ciśnienia
optymalizacja
Opis:
The article presents the effect of setting the throttle in the plenum box with swirl diffuser on the generated noise and the pressure losses. The sound power levels of the source was determined using the precision method in the reverberation room in accordance with the PN-EN ISO 3741:2011 standard. The examination was carried out for damper blade position set vertically and horizontally for full opening and at a 45 degree angle in both directions. In order to confirm the universality of the conducted experiment, the tests were carried out for two different face swirl diffuser with different shapes of air control blades and holes in the plate and for different flow rates. The multi-criteria optimization methods were used to select the best throttle position.
Źródło:
Vibrations in Physical Systems; 2019, 30, 1; 1-8
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of sound power level by using a microphone array and conventional methods
Autorzy:
Bogusławski, Grzegorz
Kopania, Joanna Maria
Gaj, Patryk
Wójciak, Kamil
Powiązania:
https://bibliotekanauki.pl/articles/127805.pdf
Data publikacji:
2019
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
sound power level
ISO methods
microphone array
intensity probe
poziom mocy akustycznej
metody ISO
macierz mikrofonów
sonda natężeniowa
Opis:
Sound power is measured to make objective comparisons between the same type of products, but also because legislation requires it. To release a new product, it is often compulsory to certify it according to International Organization for Standardization (ISO) standards, and also with national and local regulations. Determining of sound power is not a straightforward process. Sound power can be determined through the measurement of sound pressure (series 3740 methods) or sound intensity (series 9614 methods). Selecting one of the above methods depends on the purpose of the test, as well as the available equipment, desired grade of accuracy, background noise level or the test environment. Nowadays the additional methods, such as microphone arrays are used to located of the noise source and determined of pressure sound level. But the results obtained with acoustic cameras cannot be, for now, used for legislative purposes (are not ISO compliant). In this work the differences in the determination of sound power level by using conventional ISO methods and microphone arrays are determined. The system composed of a loudspeaker and a fan were used as a sound source of the noise. Sound power levels according to ISO 3746 and ISO 9614-1 were determined and were compared with the developed method by using microphone arrays techniques.
Źródło:
Vibrations in Physical Systems; 2019, 30, 1; 1-8
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Noise radiation from circular rods at low-moderate Reynolds number
Autorzy:
Kopania, Joanna Maria
Bogusławski, Grzegorz
Gaj, Patryk
Wójciak, Kamil
Powiązania:
https://bibliotekanauki.pl/articles/128113.pdf
Data publikacji:
2019
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
aeroacoustic noise
circular rod
low Reynolds number
hałas aeroakustyczny
pręt kołowy
niska liczba Reynoldsa
Opis:
The well-known dominant sources of airframe noise are associated with unsteadiness of separated and/or vortical flow regions around the high-lift system (flaps, slats) and the aircraft undercarriage (landing gear). Current practical landing gear noise prediction models are individual component - based, which means that the various components are divided into groups according to the frequency range, in which they predominantly radiate noise. Since the far-field noise spectra are approximately Strouhal - based, the emitted frequency is assumed to be directly related to their size: the large elements are responsible for the low frequency region of the spectra, and the small components for the high frequency region. On the basis of such understanding of the noise generation mechanism, the special configurations that lead to considerable noise suppression were proposed. One element of these configurations are rods with different shape and cross section. In this work the situation when circular rods are in area of laminar-turbulent flow were analysed. The measurements were carried out for single circular rod with different diameters to study the noise effect depended on Reynolds number. Far field noise for broad range of Reynolds numbers was also examined depending on distance from the source of noise.
Źródło:
Vibrations in Physical Systems; 2019, 30, 1; 1-8
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aeroacoustical study of the serrated ventilation dampers
Autorzy:
Kopania, Joanna Maria
Bogusławski, Grzegorz
Wójciak, Kamil
Gaj, Patryk
Powiązania:
https://bibliotekanauki.pl/articles/24201973.pdf
Data publikacji:
2022
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
aeroacoustics
ventilation
plane damper
serrated edge
aeroakustyka
wentylacja
przepustnica jednopłaszczyznowa
krawędź ząbkowana
Opis:
The serrated ventilation dampers for regulation of airflow volume were tested. The computer fluid flow analysis was conducted using the Comsol program. The nature of the flow through the serrated ventilation damper was analyzed to identify the different turbulence regions formed on the airflow field. Additionally, the aerodynamical and acoustical parameters of these blades of ventilation dampers with different serrated trailing and/or leading-edge were studied. The aeroacoustic studies were done in the reverberation room. The sound power level and loss coefficient were determined for the studied models.
Źródło:
Vibrations in Physical Systems; 2022, 33, 3; art. no. 2022313
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of diabetes-related complications and the cost of diabetes in Poland. The methodology and the research sample used in Economedica DM-PL Survey
Autorzy:
Bogusławski, Stefan
Wojciechowska, Agata
Smaga, Anna
Strojek, Krzysztof
Wróbel, Katarzyna
Wojtyniak, Bogdan
Juszczyk, Grzegorz
Czech, Marcin
Zdrojewski, Tomasz
Powiązania:
https://bibliotekanauki.pl/articles/2203241.pdf
Data publikacji:
2023-06-07
Wydawca:
Gdański Uniwersytet Medyczny
Tematy:
diabetes mellitus
prevalence
cost of illness
research design
Opis:
Background: Knowledge about diabetes mellitus (DM)-related complications, the direct and indirect costs incur red by patients with DM is still insufficient in Poland. Economedica DM-PL (Economedica) survey was a cross-sectional observational study that aimed to assess these issues. Material and methods: The survey was carried out in 2016 on a representative sample of 2032 diabetic patients recruited by 195 general practioners (GP) and 48 diabetologists (D) randomly selected from the national registry of physicians. Each GP and D recruited 8 to 10 patients with DM according to the specified protocol. The study included 1938 medical questionnaires (comple ted by the GPs and Ds), 1938 questionnaires about costs (completed by the patients) and 1532 treatment adherence questionnaires. Results: The Economedica survey provided new insights into DM epidemiological and cost data. 70% of patients with type-1 DM were diagnosed with the disease before the age of 40. For 76% patients with type-2 DM, it was diagnosed aeftr the age of 50. The average monthly out-of-pocket medical costs for DM patients in 2016 reached 66.2 EUR, while their non-medical costs were 36.8 EUR. Conclusions: The methodology applied in our study proved useful for providing new dimensions of DM epidemiological and cost data in Poland.
Źródło:
European Journal of Translational and Clinical Medicine; 2023, 6, 1; 31-40
2657-3148
2657-3156
Pojawia się w:
European Journal of Translational and Clinical Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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