Search results for " ultrasonic"

High spin polarization in Co2CrAl–Cr superlattice

2009

The electronic structure, magnetic properties and interface effects in Co2CrAl?Cr superstructures have been investigated by the use of first principle calculations. The results show that at the interface, a large magnetic moment and a high spin polarization can be induced by a strong ferromagnetic exchange interaction at the Cr?Co interface. However, at the CrAl?Cr interface, both the magnetic moment and the spin polarization of the Cr atoms are decreased due to a Cr?Cr antiferromagnetic interaction. It can also be found that the interface effect is only a short range effect. So, high spin polarization in Co2CrAl?Cr superlattice can be obtained. Based on this theoretical analysis, a large g…

Subjective ranking of concert halls substantiated through orthogonal objective parameters.

2015

[EN] This paper studies the global subjective assessment, obtained from mean values of the results of surveys addressed to members of the audience of live concerts in Spanish auditoriums, through the mean values of the three orthogonal objective parameters (Tmid, IACCE3, and LEV), expressed in just noticeable differences (JNDs), regarding the best-valued hall. Results show that a linear combination of the relative variations of orthogonal parameters can largely explain the overall perceived quality of the sample. However, the mean values of certain orthogonal parameters are not representative, which shows that an alternative approach to the problem is necessary. Various possibilities are pr…

Thermoelectric properties of CoTiSb based compounds

2009

Several CoTiSb based compounds were synthesized and investigated on their thermoelectric properties. The aim was to improve the thermoelectric properties of CoTiSb by the systematic substitution of atoms or the introduction of additional Co into the vacant sublattice. The solid solutions Co1+xTiSb, Co1?yCuyTiSb and CoTiSb1?zBiz were synthesized. X-ray diffraction was used to investigate the crystal structure. The resistivity, the Seebeck coefficient and the thermal conductivity were determined for all compounds in the temperature range from 2 to 400?K. The highest figure of merit for each solid solution is presented. We were able to improve the figure of merit by a factor of approximately s…

Technical Possibilities of Reducing the Sound Pressure Level Emitted into the Environment by a Power Transformer

2011

The subject presented in this paper refers to measurements and assessment of the corrected sound pressure level values (noise) occurring around a medium-power transformer. The paper presents the values of noise accompanying the operation of the power object before and after its modernization, which consisted in repeated core pressing and replacement of the cooling system. The main aim of the research work was the assessment of the influence of the repair work on the noise level emitted into the environment.

The modelling of the cathode sheath of an electrical arc in vacuum

2003

This paper presents a simple model of the fragment in the cathode electrical arc root taking into account the physical phenomena occuring on the cathode surface and the sheath. The goal is the obtainment of characteristics values of the heat flux, the electrons, and atoms density in the sheath. Computation is carried out on a one-dimensional model with a coupling between the equation obtained in the sheath and an enthalpy model of the cathode to describe the temperature evolution. In the modelling, we introduce a friction zone above the sheath edge to characterize the heavy particle interactions. Numerical simulation shows that the ionic friction phenomenon deriving from ion–atom collision …

Inspection of Laser Powder Deposited Layers

2014

Evidence for a spatial bias in the perception of sequences of brief tones

2013

Listeners are unable to report the physical order of particular sequences of brief tones. This phenomenon of temporal dislocation depends on tone durations and frequencies. The current study empirically shows that it also depends on the spatial location of the tones. Dichotically testing a three-tone sequence showed that the central tone tends to be reported as the first or the last element when it is perceived as part of a left-to-right motion. Since the central-tone dislocation does not occur for right-to-left sequences of the same tones, this indicates that there is a spatial bias in the perception of sequences. © 2013 Acoustical Society of America.

Temporal weighting of loudness: Comparison between two different psychophysical tasks

2016

International audience; Psychophysical studies on loudness have so far examined the temporal weighting of loudness solely in level-discrimination tasks. Typically, listeners were asked to discriminate hundreds of level-fluctuating sounds regarding their global loudness. Temporal weights, i.e., the importance of each temporal portion of the stimuli for the loudness judgment, were then estimated from listeners' responses. Consistent non-uniform " u-shaped " temporal weighting patterns were observed, with greater weights assigned to the first and the last temporal portions of the stimuli, revealing significant primacy and recency effects, respectively. In this study, the question was addressed…

The mid-difference hump in forward-masked intensity discrimination

2008

Forward-masked intensity-difference limens (DLs) for pure-tone standards presented at low, medium, and high levels were obtained for a wide range of masker-standard level differences. At a standard level of 25 dB SPL, the masker had a significant effect on intensity resolution, and the data showed a mid-difference hump: The DL elevation was greater at intermediate than at large masker-standard level differences. These results support the hypothesis that the effect of a forward masker on intensity resolution is modulated by the similarity between the masker and the standard. For a given masker-standard level difference, the effect of the masker on the DL was larger for a 55-dB SPL than for t…

Modeling the impact of soft tissue on axial transmission measurements of ultrasonic guided waves in human radius

2008

Recent in vitro and simulation studies have shown that guided waves measured at low ultrasound frequencies (f=200 kHz) can characterize both material properties and geometry of the cortical bone wall. In particular, a method for an accurate cortical thickness estimation from ultrasound velocity data has been presented. The clinical application remains, however, a challenge as the impact of a layer of soft tissue on top of the bone is not yet well established, and this layer is expected to affect the dispersion and relative intensities of guided modes. The present study is focused on the theoretical modeling of the impact of an overlying soft tissue. A semianalytical method and finite-differ…