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Evaluation of Uncertainty Contributions of Measurement Surface and Number of Microphone Positions in Determination of Sound Power Levels

100%
Bilgic E., Mutaf H., Kirbas C., Sadikoglu E.
Acta Physica Polonica A
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2017
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vol. 132
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issue 3
642-649
EN
Sound power level of a noise source is determined by means of sound pressure level or sound intensity level measurements performed in accordance to relevant ISO standards. The determination of sound power level according to ISO 3744, 3745 and 3746 standards is used for free field or for approximated free field conditions. Kinds of measurement surfaces, enveloping the noise source, number of microphones and their positions over the measurement surface are stated in the applied ISO standard. The effects of measurement surface and number of microphone positions on the determination of sound power level were investigated theoretically. As a measurement surface; hemisphere, parallelepiped rectangular box and cylindrical surfaces were selected. Key and additional microphone positions were taken into account in the calculations as well. Sound pressure levels of a commercially available reference sound source were measured in hemi-anechoic room using FFT with 4 Hz steps and also at 1/1, 1/3, 1/12 and 1/24 octave bands for all surfaces defined in ISO 3744 and 3746 standards. Sound power level, directivity index and uncertainty contributions resulting from measurement surfaces and number of microphone positions were calculated by using data obtained in measurements. In this paper the theoretical and experimental results are presented.
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Determination of Pulse Width and Pulse Amplitude Characteristics of Materials Used in Pendulum Type Shock Calibration Device

100%
Bilgic E.
Acta Physica Polonica A
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2017
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vol. 132
|
issue 3
857-860
EN
Calibration of shock and vibration transducers is performed by using the methods described in ISO 16063-13 and 16063-22 standards, at primary and secondary levels respectively. At secondary level, the devices, generating mechanical shock, are pendulum shock calibrator, dropball shock calibrator, pneumatically operated piston shock calibrator and Hopkinson bar shock calibrator. The main parameters and requirements of the shock calibrator devices, named here, are also given in ISO 16063-22 standard. Pulse width and pulse amplitude are the important parameters in calibration of the shock and vibration transducers. Pulse width and shape depend on the material properties. In this paper the determination of pulse width and pulse amplitude characteristics of materials used in pendulum type shock calibration device, designed in TUBİTAK UME, is presented.
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Gauss’ law of error revisited in the framework of Sharma-Taneja-Mittal information measure

64%
Scarfone A., Suyari H., Wada T.
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EN
We reformulate the Gauss’ law of error in presence of correlations which are taken into account by means of a deformed product arising in the framework of the Sharma-Taneja-Mittal measure. Having reviewed the main proprieties of the generalized product and its related algebra, we derive, according to the Maximum Likelihood Principle, a family of error distributions with an asymptotic power-law behavior.
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