Wyniki wyszukiwania - BazTech

1

Analysis of noise pollution in an andesite quarry with the use of simulation studies and evaluation indices

Kosała K., Stępień B.

International Journal of Occupational Safety and Ergonomics

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2016

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Vol. 22, No. 1

92--101

EN

This paper presents the verification of two partial indices proposed for the evaluation of continuous and impulse noise pollution in quarries. These indices, together with the sound power of machines index and the noise hazard index at the workstation, are components of the global index of assessment of noise hazard in the working environment of a quarry. This paper shows the results of acoustic tests carried out in an andesite quarry. Noise generated by machines and from performed blasting works was investigated. On the basis of acoustic measurements carried out in real conditions, the sound power levels of machines and the phenomenon of explosion were determined and, based on the results, three-dimensional models of acoustic noise propagation in the quarry were developed. To assess the degree of noise pollution in the area of the quarry, the continuous and impulse noise indices were used.

2

Acoustic models of bus interior regarding the different points of working combustion engine

Komorski P., Szymański G. M.

Combustion Engines

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2015

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R. 54, nr 3

619--625

EN

The article presents an analysis of sound propagation inside the selected road transport vehicles in the city of Poznan. The research was based on the measurements of the levels of acoustic pressure generated by several bus combustion engines during an acceleration process – at various rotation speed of the crankshaft in combustion engines. Then taking into consideration the measurements and the assumptions of acoustic holography in domain of time, several acoustic models of sound propagation inside the buses at various points on the working combustion engines were elaborated.

PL

W artykule przedstawiono analizę propagacji dźwięku wewnątrz wybranych pojazdów drogowych komunikacji miejskiej miasta Poznań. Przeprowadzono badania polegające na pomiarach ciśnienia akustycznego generowanego przez autobusowe silniki spalinowe w trakcie przyspieszania – przy różnych prędkościach obrotowych wału korbowego silników spalinowych. Następnie na podstawie wyników pomiarów oraz założeń holografii akustycznej w dziedzinie czasu, opracowano modele akustyczne rozkładu poziomu dźwięku wewnątrz autobusów w różnych punktach pracy silników spalinowych.

3

Modelowanie rozkładu wskaźników hałasu ulotu w otoczeniu linii wysokiego napięcia

Wszołek T.

Przegląd Elektrotechniczny

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2010

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R. 86, nr 11b

111-114

PL

W pracy pokazano model do obliczania poziomu mocy akustycznej jednostkowej długości przewodów fazowych w funkcji intensywności opadów, stanu technicznego oraz wysokości zawieszenia przewodów dla dowolnego układu geometrycznego linii WN. Przykładowe obliczenia rozkładu wskaźników długookresowych hałasu ulotu przeprowadzono w przekrojach poprzecznych oraz w postaci mapowej dla zróżnicowanych uwarunkowaniach terenowych.

EN

The paper shows a model to calculate the sound power level of unit length phase conductors as a function of rainfall intensity, the technical condition and the height of the suspended conductors for any geometric arrangement of power line. Sample calculations of the distribution of the long-term noise indicators were performed in cross sections and the form of maps in diverse terrain considerations.

4

Study of the Effect of the Orchestra Pit on the Acoustics of the Kraków Opera Hall

Kamisiński T., Burkot M., Rubacha J., Brawata K.

Archives of Acoustics

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2009

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Vol. 34, No. 4

481-490

EN

The orchestra pit acoustics are mostly assessed by musicians and directors of musical performances using the sense of hearing, i.e. in a subjective manner. This paper proposes a method for an objective assessment using such parameters as Support (ST) and Sound Strength (G), which are obtained by measurements. ST defines the quality of how orchestral musicians hear one another in the orchestra pit, whereas G determines the impression of loudness at selected points of the auditorium. To determine the value of these parameters, acoustic measurements were performed in the orchestra pit and the auditorium of the Kraków Opera Hall. A numerical model was also developed, which was employed for multivariant computer simulations using the CATT-acoustic software. The purpose of the paper is to present a methodology for objective assessment of the orchestra pit acoustics.

5

Acoustic modelling of machines using the inversion method for the purposes of the acoustic assessment of machines

Pleban D.

Archives of Acoustics

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2007

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Vol. 32, No. 2

321-327

EN

Issues related to the development of acoustic models of machines are important factors both in the design of low-noise machines and in the prediction of machines noise. The acoustic modelling of machines may be carried out using a set of omni-directional substitute sound sources, located in points related to the functional elements of machines. The optimal parameters of these sources may be determined using an inversion method. To calculate these parameters by using the inversion method one must know the real distribution of sound pressure around the machine. This requires the determination, on the surface of hemisphere, of both the distribution of the amplitude of sound pressures, as well as the distribution of phase shift angles between acoustic signals. Computer simulations yield optimal parameters (sound power) for the individual omni-directional sound sources. Using the calculated parameters of the substitute sources it is possible to determine the radiation characteristics and to carry the acoustic assessment of the machine.

6

Seismic structure of the crust-mantle transition zone of the Ukrainian shiels

Starostenko V., Kharitonov O., Tripolsky A.

Acta Geophysica Polonica

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1999

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Vol. 47, nr 2

185-201

EN

The Ukrainian shield is one of the largest heterogeneities of the East European Platform. The deep seismic sounding results indicate a blocked layred structure of the shieldsand enabled us to separate several long submeridonal crustal blocks, notably differing from each other in thickness, which are cut deep falts of mantle origin. The geologic and geophysical features of these blokcs suggest that they belong to protoplatform structures with 38-51 km thick crust and protogeosynclines with Moho-discontinuity depth to 65 km. An analysis of dynamic characteristics of reflection waves shows that within the protoplatform blokcs the Moho-discontinuity is mainly a sharp boundary of the first order with longitudinal waves velocity contrast corresponding to the basic-ultrabasic rocks contact. In the protogeosynclinal systems, a 3-9 km thick crust-mantle transition zone is distinguished. By using of combinated kinematic-dynamic analysis for the Ukrainian shielld, several of acoustic models of the crust-mantle transition zone were distinguished. The nature of this zone may be either a gradual transition from mafic to ultramafic rocks or its origin may be results of the underplanting.

7

Uniform decay rates for solutions to a structural acoustics model with nonlinear dissipation

Avalos G., Lasiecka I.

Applied Mathematics and Computer Science

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1998

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Vol. 8, no 2

287-312

EN

In this work, the asymptotic behavior of solutions to a coupled hyperbolic/parabolic-like system is investigated. It is shown that with both components of the equation being subjected to nonlinear damping (boundary damping for the wave component, interior for the beam), a global uniform stability is attained for all (weak) solutions.