Vibration-Assisted Ball Burnishing

Vibration-Assisted Ball Burnishing is a finishing processed based on plastic deformation by means of a preloaded ball on a certain surface that rolls over it following a certain trajectory previously programmed while vibrating vertically. The dynamics of the process are based on the activation of the acoustoplastic effect on the material by means of the vibratory signal transmitted through the material lattice as a consequence of the mentioned oscillation of the ball. Materials processed by VABB show a modified surface in terms of topology distribution and scale, superior if compared to the results of the non-assisted process. Subgrain formation one of the main drivers that explain the change in hardness and residual stress resulting from the process.

The effects of microhabitat specialization on mating communication in a wolf spider

Animal signals experience selection for detectability, which is determined in large part by the signal transmission properties of the habitat. Understanding the ecological context in which communication takes place is therefore critical to understanding selection on the form of communication signals. In order to determine the influence of environmental heterogeneity on signal transmission, we focus on a wolf spider species native to central Florida, Schizocosa floridana, in which males court females using a substrate-borne vibratory song. We test the hypothesis that S. floridana is a substrate specialist by 1) assessing substrate use by females and males in the field, 2) quantifying substrate-specific vibratory signal transmission in the laboratory, and 3) determining substrate-specific mating success in the laboratory. We predict a priori that 1) S. floridana restricts its signaling to oak litter, 2) oak litter best transmits their vibratory signal, and 3) S. floridana mates most readily on oak litter. We find that S. floridana is almost exclusively found on oak litter, which was found to attenuate vibratory courtship signals the least. Spiders mated with equal frequency on oak and pine, but did not mate at all on sand. Additionally, we describe how S. floridana song contains a novel component, chirps, which attenuate more strongly than its other display components on pine and sand, but not on oak, suggesting that the ways in which the environment relaxes restrictions on signal form may be as important as the ways in which it imposes them.

Research of Data Mining of Vibratory Signal Based on Rough Set Theory

This paper sets three fault modes of rotor misalignment, pedestal looseness and rub between rotor and stator by rotor experimental platform and collected corresponding vibratory signals. Part of vibratory signal energy feature was extracted in the time field. As feature parameter of energy, the signal collected was mined using rough set theory, fault diagnosis was established on this basis. Validity of rule was verified by remaining vibratory signal, the result indicates diagnosis are accurate, fault diagnosis rule is meaningful.

Comparison of denoising methods for the early detection of fatigue bearing defects by vibratory analysis

The aim of this article is to show the interest of three major denoising methods for the improvement of the sensitivity of scalar indicators (crest factor, kurtosis) within the application of conditional maintenance by vibratory analysis on ball bearings. The case of a bearing in good condition of use is considered. The distribution of amplitudes in the vibratory signal is of the Gaussian kind. When the bearing is damaged, the appearance of spalling comes to disturb this signal, modifying this distribution. This modification is due to the presence of periodical impulses produced each time a rolling element meets a discontinuity on its way. Nevertheless, the presence of background noise induced by random impulse excitations can have an influence on the values of these temporal indicators. The denoising of these signals allows to improve the sensitivity of these indicators and to increase the reliability of the diagnosis.

Vibratory communication signal produced by male western conifer seed bugs (Hemiptera: Coreidae)

We tested the hypothesis that the western conifer seed bug, Leptoglossus occidentalis Heidemann, uses a substrate-borne vibratory signal for short-range communication. To record such a signal we used computers equipped with data-acquisition hardware and software, microphones sensitive to sonic and (or) ultrasonic frequencies, membrane-type and piezoelectric speakers capable of emitting sonic and ultrasonic sound, and piezoelectric devices capable of emitting low-level, low-frequency vibrations. By tapping their abdomen on substrate, males produced a wide-band vibratory signal 20 dB (sound pressure level; 0 dB = 20 µPa) above ambient sound, with dominant frequencies of 115 ± 10 and 175 ± 15 Hz and a distinct temporal pattern. There was no evidence for (i) ultrasonic signal components; (ii) signals produced by females or nymphs, or (iii) repeated trains of signal pulses. In two-choice arena experiments, males and females preferred the played-back recording of the male-produced substrate-borne signal over silent controls, whereas nymphs showed no preference for either stimulus. In two-choice dowel experiments with hickory wood or lodgepole pine crossbeams, females (unlike males or nymphs) preferred played-back recordings of the same signal over controls. In two-choice field experiments, this signal emitted in the air by piezoelectric devices or transferred through a wire to lodgepole pine branches attracted more L. occidentalis than did silent controls. Our data support the hypothesis that L. occidentalis uses a substrate-borne vibratory signal for short-range communication. The use of such a signal is consistent with reports on communication by other true bug species.

Courtship Communication in Meadow Katydids: Female Preference for Large Male Vibrations

Males of the katydid Conocephalus nigropleurum (Orthoptera: Tettigoniidae) shake their body to produce a substrate-borne vibratory signal in the context of courtship and mate attraction. We measured the physical parameters of this tremulation signal and then tested its effectiveness in eliciting taxis by virgin females. We also investigated the role of these vibrations in the choices made by females of larger males as mates. A search for correlations between male weight and vibratory signal parameters revealed a strong negative relationship to inter-pulse interval (ipi). In two-choice playback experiments females oriented towards tremulation vibration when it was the only vibration stimulus provided. In further playback experiments females also distinguished conspecific tremulation from a control vibration. When offered simultaneous presentations of tremulation signals that differed in ipi, females moved toward the stimulus with the shorter ipi indicative of a larger male. This is the first study to demonstrate that tremulation signalling by male katydids encodes critical information on body size, and that females discriminate among different vibratory signals in favour of those indicating a larger male.