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Abstract

This article presents results of investigations of the angle of directional hearing acuity (ADHA) as a measure of the spatial hearing ability with a special emphasis on people with hearing impairments. A modified method proposed by Zakrzewski has been used - ADHA values have been determined for 8 azimuths in the horizontal plane at the height of the listeners' head. The two-alternative-forced-choice method (2AFC), based on a new system of listeners' responses (left - right instead of no difference - difference in location of sound sources) was the procedure used in the experiment. Investigations were carried out for two groups of subjects: normal hearing people (9 persons) and hearing impaired people (sensorineural hearing loss and tinnitus - 9 persons). In the experiment different acoustic signals were used: sinusoidal signals (pure tones), 1/3 octave noise, amplitude modulated 1/3 octave noise, CCITT speech and traffic noises and signals corresponding to personal character of tinnitus for individual subjects. The results obtained in the investigations showed, in general, a better localization of the sound source for noise type signals than those for tonal signals. Inessential differences exist in ADHA values for particular signals between the two groups of subjects. On the other hand, significant differences for tinnitus signals and traffic noise signals were stated. A new system of listeners' responses was used and appeared efficient (less dispersion of results compared to the standard system).

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Authors and Affiliations

Marek Niewiarowicz
Tomasz Kaczmarek
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Abstract

The research on the coupling electromagnetic effect was studied in this paper, in consideration of the wreaking damage of the powerful electromagnetic pulse to the electronic products. The characteristic of the metallic via and stub interconnect with the coupling voltage was calculated by the model, which was the transfer function F( f ) of the protection circuit parameters of DC power source. The research showed that: the smaller radius of Metallic via, the lower amplitude of F( f ), the less energy of a power electro- magnetic pulse (PEP); the higher increase of the width of the stub interconnect, the bigger reduction of the characteristic impedance of plane wave coupling, the depth of the notch band significantly narrowed. The simulations and experiments were done to compare the protection effects of protection circuits with different parameters at last. The results showed that the protection circuit designed could be highly advantageous in protecting the DC power source in this article.

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Authors and Affiliations

Xiaofei Xu
Denghua Li
Shuhui Yang
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Abstract

In this work, the effect of heat transfer during explosive welding (EXW) and post-processing annealing on the microstructural and chemical composition changes have been thoroughly analysed using scanning and transmission electron microscopies and X-ray synchrotron radiation. Several combination of explosively welded metal compositions were studied: Ti with Al, Cu with Al, Ta or stainless steel, stainless steel with Zr or Ta and Ti with carbon steel. It was found that the melted metals exhibit a strong tendency to form brittle crystalline, nano-grained or even amorphous phases during the solidification. For all analysed metal combinations most of the phases formed in the zones of solidified melt do not appear in the equilibrium phase diagrams. Concurrently, the interfacial layers undergo severe plastic deformation forming nano-grained structures. It has been established that these heavily deformed areas can undergo dynamic recovery and recrystallization already during clad processing. This leads to the formation of new stress-free grains near the interface. In the case of low temperature and short time post processing annealing only the melted zones and severely deformed layers undergo recovery and recrystallization. However, drastic changes in the microstructure occurs at higher temperature and for longer annealing times. Applying such conditions leads to diffusion dominant processes across the interface. As a consequence continuous layers of intermetallic phases of equilibrium composition are obtained.

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Authors and Affiliations

H. Paul
M.M. Miszczyk
A. Gałka
R. Chulist
Z. Szulc

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