Akustika

The results of theoretical and experimental research of the impedance of an anisotropic structure in the low frequency range are presented. It is shown that taking into account the inhomogeneous distribution of mass along the length of the structure has a great influence on the value of the impedance of an anisotropic structure. Based on the results obtained in the mathematical model, expressions are proposed for calculating the impedances of anisotropic structures in the low frequency range.

Sergey A. Rykov

Irina Kudryavtseva

Sergey V. Rykov

LOW-FREQUENCY IMPEDANCE OF ANISOTROPIC ENGINEERING DESIGN

各向异性工程设计的低频阻抗

On the contrary the infrasonic region of the spectrum is still under investigation. The first study on the presence of the infrasound in air go back to the end of the 19th century and its effects on the human beings have been investigated since the World War II. In this paper is presented an overview of the technologies used to detect infrasound in different research fields, pointing out their pros and cons. System specification for urban area infrasound noise monitoring require transportability, robustness, reduced dimensions to avoid large space occupation and low cost devices for a distributed monitoring.

Fabio Lo Castro

Andrey Vasilyev

Sergio Larossi

Massimilliano De Luca

INFRASOUND MONITORING TECHNOLOGIES

次声监测技术

This article describes an experimental method of designing mufflers based of finite element modelling and the results of experimental study. We have presented the results of studies, including in the form of sound pressure distribution over the internal volume and transmission losses of the developed designs of the muffler. Based on the results of these studies, a design with the best vibroacoustic features was selected. The results of experimental testing of the developed and manufactured design of a catalytic silencer in a car are presented.

Rakhmatdzon Rakhmatov

Vladimir Galevko

Givi Nadareishvilli

Valeriy Zuzov

IMPROVEMENT OF ACOUSTIC FEATURES OF CATALYTIC MUFFLERS

催化消声器声学特性的改进

The article considers the determination of the impedance of the acoustic liner sample on the basis of numerical simulation of physical processes in a honeycomb resonator with a grazing incidence of sound waves. The computational domain is the test section of a grazing incidence impedance tube with an acoustic liner sample. The liner sample is a single honeycomb resonator with a depth of 14 mm and an open area percent of 4.2%. Numerical simulation is performed based on the direct solution of the non-stationary compressible Navier-Stokes equations in a three-dimensional formulation. The pressure-time and velocity-time signals are recorded in the numerical simulation and processed by Dean's method and the direct method (from the ratio of acoustic pressure to normal acoustic velocity). The comparison of impedances obtained by the two methods demonstrates a good agreement with each other.

Igor Khramtsov

Vadim Palchikovskiy

Oleg Kustov

DETERMINATION OF THE IMPEDANCE OF A HONEYCOMB RESONATOR BY DEAN’S METHOD AND DIRECT METHOD IN A COMPUTATIONAL EXPERIMENT WITH GRAZING INCIDENCE OF WAVES

利用Dean方法和直接方法在掠入射波的计算实验中确定蜂窝谐振器的阻抗

The coefficient of vibrational energy loss is a physical and mechanical characteristic, the accuracy of calculation of vibroacoustic characteristics of corresponding machines at the stage of their design to a great extent depends on its value.

Veronika Krutova

Besarion Meskhi

THEORETICAL STUDY OF THE CLOSED BAR LOOS FACTOR

闭合条松动因子的理论研究

The article applies a methodology for determining the acoustic power of air-borne sound which is generated by the vibration of machinery components or the machine itself. The calculation of the acoustic power level is realized by measuring the vibration acceleration and integrating it to the vibration velocity of the rigid surface of the machinery or its component. The methodology is verified when determining the acoustic power level of operated spinning headstocks on a test facility. Undesirable noise emissions of spinning headstock bearings, as well as their operating condition, can be monitored by measuring kinematic parameters, measuring vibration acceleration and its subsequent integration. The vibration velocity was used to determine the A-weighted level and Z-weighted level of the acoustic power and at the same time to evaluate the operating condition of the two selected spinning units. The article also evaluates the importance of the correct choice of the measuring point of the analyzed spinning headstock on the test equipment when determining the level of acoustic power, which has a decisive influence on the uncertainty of the measurement.

Stanislav Žiaran

DETERMINATION OF THE ACOUSTIC POWER LEVEL EMITTED BY A MACHINE COMPONENT BY MEASURING VIBRATION

通过测量振动确定机器部件发出的声功率级

In this investigation a novel hybrid spiral microphone array system is designed and constructed to maximize the overall performance of the array under the constraint that the array must be portable and capable of being transported in a small hatchback vehicle. Several microphone array designs are considered before settling on a modified Fermat spiral with microphones located exclusively on the axes of the array, enabling the array to be quickly disassembled into a small number of sections, transported to a remote location, and then re-assembled. The performance of the new microphone array is tested against an existing microphone array that was also designed for portability but with a more conventional logarithmic spiral design. The resolution of the new hybrid spiral array is found to greatly exceed the resolution of the conventional portable microphone array.

Matthew R. Aldeman

Jin Ho Jo

TESTING A NOVEL HYBRID SPIRAL MICROPHONE ARRAY DESIGNED FOR PERFORMANCE AND PORTA

测试一种新型混合螺旋微型麦克风阵列的设计，旨在实现性能和便携性

There are not only theory but also the empirical formula to deal with the problem of sound propagation in ocean. As such the Normal mode and Francois-Garrison are typical methods. Optimum sound propagation in ocean is the way we unify these two methods. In this paper, we investigate the transmission losses of both Normal mode and Francois- Garrison at some frequencies (170Hz, 800Hz, 100 KHz) at shallow water conditions (Tonkin gulf). The calculated and simulation results show that the optimum is achieved when the Normal mode is used at low frequencies whereas the Francois-Garrison is used at high frequencies.

Tran Cao Quyen

OPTIMUM PROPAGATION IN OCEAN: THE COMPARISON BETWEEN NORMAL MODE AND EMPIRICAL FRANCOIS-GARRISON FORMULA

海洋中最佳传播：正规模型与经验Francois-Garrison公式的比较

The problem of diffraction of a spherical sound wave by a thin hard half-plane is considered. The expression of the total field at any position in the space around the half-plane is composed of two geometrical components and a third one which originating from the edge of the half-plane. This paper takes the expression of the edge-diffracted field due to a sound doublet, as formulated in the Biot-Tolstoy theory of diffraction, BTD, but rearranged for the Dirac-like pulse by Medwin. The present paper presents a development in the frequency domain of the Fourier transform of the exact expression of the edge-diffracted field as given in the time domain. This solution is composed of a serial development, expressed in simple trigonometric integral functions, and which away from the geometrical optics boundaries shows a quite rapid convergence to the numerical Fourier transform of the exact time-domain expression. The presented solution may be used as a good approximation in simulations and in real case predictions of sound scattering by thin straight-edged noise barriers.

Djamel Ouis

DIFFRACTION OF A SPHERICAL WAVE BY A HARD HALF-PLANE: POLYNOMIAL FORMULATION OF EDGE-DIFFRACTED FIELD IN THE FREQUENCY DOMAIN

硬半平面上的球面波衍射：频域中边缘衍射场的多项式公式

The contribution is devoted to the issue of measuring vibrations and possibly also noise using microcontroller technology. The contribution contains a theoretical introduction to the issue, and further describes the practical hardware implementation of the measuring system, the basis of which is a suitable microcontroller. Part of the contribution is also an analysis of the appropriateness of using such a measurement technique for application specifically in the field of railway constructions and buildings. The conclusion includes recommendations for other workplaces that would like to use this method of measurement.

Abbreviation
Journal Impact	0.22
Quartiles(Global)	ACOUSTICS(Q4)

ISSN	1801-9064, 2570-8775
h-index	12

Publication Information	Publisher: Studio D - akustika s. r. o.，Publishing cycle: ，Journal Type: journal，Open Access Journals: No
Basic data	Year of publication: 2012，Proportion of original research papers: 100.00%，Self Citation Rate:0.00%， Gold OA Rate: 0.78%

Akustika

Journal Citation Format

A journal article with 1 author

A journal article with 2 authors

A journal article with 3 authors

A journal article with 5 or more authors

Books Citation Format

Thesis Citation Format

Web sites Citation Format

Patent Citation Format

Staying up late manually editing references? ivySCI automatically matches journals and helps you generate references with a single click.

Share Submission Experience