The results of prediction of the probability for normal situation, failure situations with the fault 1 and 2 are shown in Figure 4 for Data Set 1 and in Figure 5 for Data Set 2. From these results, we can find that the fault probability clearly exhibits large values in the sub-data sets corresponding to the failure situation. More precise prediction of the fault probability is possible by considering correlation information of lower and higher orders, because the correlation characteristics (of lower and higher orders) between sound and vibration change after failure. Thus, the proposed method to detect precisely the change of correlation information is useful in the de- tection of machine failures.
A large amount of work on applying SEA to buildings is summarised by Craik , the work focussed on the determination of subsystem properties and coupling loss factors and the evaluation of SEA models comprising many subsystems. Craik  investigated the use of SEA to predict the sound pressure and vibration level due to direct and flanking sound transmission in a heavyweight building comprising many rooms and plates. The SEA coupling loss factors are validated using simplified ESEA. Comparing the measured and SEA predicted energy levels shows good agreement, with larger errors at low frequencies, presumably where the few local modes of each subsystem dominate the response. It is noted that some of the large errors observed were due to the omission of airborne flanking paths in the SEA model. Craik [27, 28] showed the significance of in-plane waves when dealing with structure-borne sound transmission is large buildings comprising X- and T- junctions, both of which are key in converting bending waves into in-plane waves, and visa versa, across the junction. By comparing SEA models with and without in-plane waves to measured sound pressure and vibration levels, it was shown that that the further away the receiver subsystem is from the source subsystem the larger role in- plane waves, and flanking transmission played in sound transmission. The papers by Crocker, Price and Craik [19, 20, 26-28] amongst others show the development of SEA successfully being used to predict sound pressure and vibration levels for direct sound transmission and flanking transmission. Moving from research that looks at direct sound transmission to those that include flanking sound transmission as well, the SEA models include more structural coupling than radiation coupling, as in large building structural coupling provides the flanking transmission with radiation coupling providing the final path to give a sound pressure level in a room.
In sound or vibration analysis from various rotating objects, it is necessary to know which number of rotations makes the noise louder. Then each component level for the rotation can be analyzed by recording rotation information (pulse vibration etc.) as well as the sound or vibration signals.
Sound & Vibration Technology Ltd. (SVT), located on Millbrook Proving Ground in Bedfordshire, UK, is a provider of sound and vibration test-based consulting. For more than 30 years, SVT has specialised in providing solutions for a wide range of engineering problems through application of advanced noise and vibration testing methods and analysis. SVT provides leading edge, integrated services to automotive, aerospace, rail and industrial clients in Europe, the Far East and the US. These services include:
We conclude that pythons, and possibly all snakes, can hear, but that they lost effective pressure hearing with the loss of a functional outer and middle ear. Instead, snakes have maintained or developed vibration sensitivity as good as that found in any terrestrial vertebrate, enabling them to maintain insensitive sound detection via sound-induced head vibrations. The loss of effective pressure hearing is reinforced by the observation that the same sensory cells detect both substrate vibrations and aerial sounds (Hartline, 1971). The high thresholds to sound pressure measured in the present study suggest that sound-pressure hearing may be of little biological relevance to pythons in the detection of prey or predators, or in interspecific communication. Usually, the frequency of maximum sensitivity of the audiogram matches the peak energy of vocalizations, but in snakes the maximum sensitivity is at much lower frequencies than their sound production (Young, 2003). The peak energy of snake sounds seems to match the sensitivity of lizards (Brittan-Powell et al., 2010), perhaps as a relic from the nearest common ancestor of these two groups. Therefore, snake vocalizations are likely directed at mammalian or bird predators and not towards other snakes. This further implies that snakes, with the loss of the tympanic middle ear, may also have lost the ability to communicate with conspecifics by means of sound pressure. Their high vibration sensitivity, however, enables them to sense vibrations at very low levels, which likely serves a function in communication and for detecting predators and prey.
The similar properties of the VEP and the AEP might be explained if energy contained in one modality were simply channelled into the other. Moran and Rowley (1975), citing earlier authors, indicate that cockroaches can detect sound because it induces substratum motion which is picked up by the vibration-sensitive SGO, a possibility that Autrum (1941) first considered and felt unable to reject, because of uncertainty about the level of induced vibration in his experiments, despite his efforts to reduce this to a minimum. Because of its expected inefficiency, this is a physically implausible suggestion for most potential substrata for all but the loudest sounds, but it is difficult to refute convincingly in principle because the SGO is so sensitive to vibration (Autrum and Schneider, 1948; Schnorbus, 1971), and the idea appears never to have been examined critically. It was tested here using an approach opposite to Autrum’s: an isolated leg was mounted atop a short rigid pillar, and the tarsus was attached to a flexible support with well-understood vibrational properties, a cantilever beam extending from the pillar (Fig. 7A). Reproducible, small-amplitude, self-damped oscillations of the beam at its fundamental frequency were induced by brief taps from a metal probe attached to a small speaker. The voltage drive to this was adjusted to register a strong VEP response (recorded through flexible 75 m m diameter wires implanted in the leg, to uncouple this mechanically from other apparatus). In this configuration (the most sensitive for exciting the SGO according
Knowledge on acoustical materials is essential for the practicing noise control engineer. Without this knowledge, cost effective control of noise become more a matter of chance than of intelligent design. In this journal, (Ancuta, 2011) the author described and compared different type of acoustical materials, such as absorptive barrier materials, silencer, damping treatments and vibration isolators. The major characteristics for each of these categories are summarized. The first categories function is to absorb or attenuate airborne sound waves. Some of the vibrating object that in contact with a medium has created sound waves whose propagation through the medium is to be minimized. The next category function is vibration isolation that is to minimize the transmission of shaking forces into a floor or other solid structure.
63 Based on this structure and operating process, its dynamic responses of surface vibration, airborne sound and acoustic emission can be understood as shown in Figure 3.2. There are two main excitation sources: external forces such as fluctuation loads from system misalignment and imbalance, and internal excitations such as the asperity contact in boundary operation. These excitations will cause structure-borne vibrations and acoustic emissions of the bearing vibrations system. These structure-bore dynamic responses then radiate airborne sound. In addition fluid dynamics such as oil pressure fluctuations and flow turbulences also produces airborne sounds.
Drosophila melanogaster hear with their antennae: sound evokes vibration of the distal antennal segment, and this vibration is transduced by specialized mechanoreceptor cells. The left and right antennae vibrate preferentially in response to sounds arising from different azimuthal angles. Therefore, by comparing signals from the two antennae, it should be possible to obtain information about the azimuthal angle of a sound source. However, behavioral evidence of sound localization has not been reported in Drosophila. Here, we show that walking D. melanogaster do indeed turn in response to lateralized sounds. We confirm that this behavior is evoked by vibrations of the distal antennal segment. The rule for turning is different for sounds arriving from different locations: flies turn toward sounds in their front hemifield, but they turn away from sounds in their rear hemifield, and they do not turn at all in response to sounds from 90 or − 90 deg. All of these findings can be explained by a simple rule: the fly steers away from the antenna with the larger vibration amplitude. Finally, we show that these behaviors generalize to sound stimuli with diverse spectro-temporal features, and that these behaviors are found in both sexes. Our findings demonstrate the behavioral relevance of the antenna ’ s directional tuning properties. They also pave the way for investigating the neural implementation of sound localization, as well as the potential roles of sound-guided steering in courtship and exploration.
manufacturing engineering faculty itself, more specifically in the Block B’s laboratory. The limitation of this project is focused on the investigation of speed and angular misalignment of the rig. It is performed up till the limitation of the machine’s speed as well as the angular misalignment. Vibration is detected using the vibration meter (DIGI VIBRO (Model-1363)) and commercial mobile applications such as Sound Analyser and Frequency Sound Generator is used for sound detection. Other than that, ISO 10816, Vibration Severity Standards is referred for vibration severity of misalignment at different RPM.
Resilient wheels are extensively used in urban rail transit, especially for tramway systems, owing to its advantages in noise reduction. A new type of resilient wheel for a metro is designed, and its characteristics of vibration and sound radiation, including the rolling noise of a resilient single wheel coupled with a track, are studied in this paper. A two-step research is presented. Firstly, laboratory experiments were conducted to obtain the vibration response of the designed resilient wheel under the radial excitation on its tread. Secondly, the rolling noise model of the resilient wheel coupled with a slab track used in a metro line is developed. The wheel model is based on the 3D finite element and boundary element methods and verified by using the experimental results obtained from the laboratory. The track vibration model is based on the wavenumber finite element method, and the track sound radiation is calculated by using an efficient frequency-domain Rayleigh method. The interaction of the resilient wheel and the slab track is analyzed considering the measured wheel/rail roughness of the metro. The contribution of the resilient wheel to the reduction of wheel/rail system noise is analyzed. The results show that the resilient wheel can effectively reduce the wheel/rail rolling noise by approximately 2 dB(A) to 3 dB(A), mainly because the radiated noise by the rail is reduced. In addition, the elastic modulus of the rubber has an important influence on the noise reduction of resilient wheels. Keywords: Resilient wheel, Wheel/rail rolling noise, Noise reduction, Laboratory experiment, Finite element and boundary element methods
Because of the complexity of energy storage mechanism and energy storage control process of circuit breaker, power supply fluctuations, drive mechanism jams, shedding of the energy storage spring, and failure of the limit switch may occur, ultimately leading to the circuit breaker cannot complete opening and closing operation normally. Therefore, the experiments of normal energy storage, high energy storage voltage, low energy storage voltage, mechanism jamming, and spring shedding are carried out respectively, and sound-vibration signals are collected under different states. Changing the voltage level in the energy storage process of circuit breaker can simulate the state of high voltage and low voltage. The wooden stick is used to clamp the rotating
Abstract: The wheel of vehicles is not pure rolling on the rail for the track irregularity, but with a small vertical and horizontal relative displacement. The relative displacement produces the wheel rail force and causes the vibration of the wheel and rail, which is transmitted to the air and produces noise. Therefore, it is of great significance to study the wheel's vibration and sound radiation under the track irregularity conditions. In this paper, the wheel-rail coupling dynamic analysis model of metro vehicle was established by using UM software and was researched by numerical calculation method, the wheel-rail contact force under irregularity excitation was obtained. Then the acoustic calculation model of the rigid wheel and the resilient wheel was established. Combined with the structural finite element method and the acoustic boundary element method, the structural response obtained by transient dynamic analysis was used as the boundary condition to study the acoustic radiation characteristics and the noise reduction effect of the resilient wheel. The study results show that under the vertical excitation of wheel-rail, compared with rigid wheel, the use of resilient wheel can inhibit the vibration for rim, tread and web. The vibration acceleration attenuation of the web is most significant, from 97m/s2 to 58m/s2. It is because of the vibration reduction function of the rubber body for the resilient wheel. The sound power level of the resilient wheel has a slight increase in the low frequency range and has a slight decrease in the high frequency range, in the whole calculated frequency range the sound power level of the resilient wheel decreases by 10.1 dB. These provide a good reference for the resilient wheel application in metro vehicle.
cynosure of religious chant up to the present day (Beck, p. 9). Meditation and chanting, like light and colour, are all methods still used in complementary medicine to create emotional, neurological and physical changes. ‘External stimuli, like sound, light and colour can interfere with and/or cancel out other incoming sense stimulus and can clear thought activity’ (Ellingson, 1979, p. 149). ‘Sounds can also modulate simultaneous changes in the autonomic, immune, endocrine, and neuropeptide systems’ (Campbell, 2000, p. 148). Buddhist adepts of sound chant Om, a syllable they consider to be sacred for its ability to draw the practitioner into a meditative state, bringing focus and concentration. As a chant, the sound Om is voiced in three parts, A, U, M and intends to lead the adept towards their highest faculty of consciousness. ‘A’ stands for the waking state of consciousness, ‘U’ for the dream state of consciousness and ‘M’ for the deep sleep phase of consciousness. Elocution and phonetic treatment are regarded to be important factors when attempting to achieve desired brain-mind outcomes. Kay Gardner (1941–2002), was a musician, composer, author, and musical producer involved in creating music for healing purposes. Gardner identified drone, repetition, harmonics, harmony, vibration, vibrato, melody, resonance, rhythm and beat as musical elements which can psychologically impact on humans (Gardner 1990, pp. 227–229 cited by Bergquist, 1997). Some sounds can be produced in a resonant and nasal manner while others are full and resonant. Mantra yoga is an art of chanting in which precise mouth postures (formants) and repetition of exact intervals are adopted. The sound, if created with clear intent and execution can elevate the perceptual sensitivity of the performer, transforming their sensibility, way of thinking, state of soul and moral character. ‘All vowels should be pronounced strong and sonant and with the thought affirmation of intent’ (Beck, 1995, p. 27). If the phoneme is properly constructed with the mouth, a plethora of harmonics can be created, which vibrate within the practitioner; a sensation beyond standard experience.
The location of a single-point defect due to the load zone can affect fault-signature saliency. Inner-race faults periodically rotate in and out of the load zone this model was developed to investigate this problem. This model showed the power spectrum of machine vibration of inner-race defect to be comprised of peaks separated by FIRF and peaks within the groups separated by FS. This detector was then applied to machine-vibration data, and the peaks it exhibited that were spaced by FIRF were counted and used as the fault index. Inner-race defects fault-index counts are one to two orders of magnitude greater than healthy bearings for most values of m. Single-point defects fault-index counts are low (between 0–5) for all values of m. Rolling-element defects when FIRF is an integer multiple of FRE. This fault-signature model and detection scheme to handle rolling-element or cage defects.
Fig. 33: Amplitude of the frequency response function between the output signal of a microphone placed at about 0.5 m over the centre of the panel and the force transmitted by a shaker to the panel in the 20 Hz-1 kHz frequency range (left hand side) and in the 20 Hz-2kHz frequency range (right hand side). The solid line represents the sound pressure when the control system is off and the faint line when all the five control loops are implemented with maximum stable gains.
Tolerance limits of noise and vibration Limit values in the human sphere are minutely regulated by standards and regulations to meet particular needs (ISO 2631-1, 1997). However, no in- formation is available in the sphere of farm animals at all. Vets and ethologists agree that animals are just as sensitive as humans. Sensitivity in animals assumes even greater importance when optimum yield is at stake.
three aforementioned methods are hard to be implemented and not really effective due to design complexity, costly, and unfeasible at lower frequency. The latter approach using discrete masses or known as passive vibration absorbers, however, are more sound because they do not contribute significant additional vibration energy to the structure, besides demonstrated to yield substantial attenuation in structural vibration [8-10]. Nevertheless, it produces drawbacks such as the obvious weight increase, and improperly placement and frequency tuning of vibration absorber may result in large increase of vibration level [9,10].
In spite of these studies and knowledge gained thus far, it has not yet reached a situation where a person able to find a vibration control method to fit all vibration situations. In fact, the first three aforementioned methods are hard to be implemented and not really effective because of its design complexity, costly and unfeasible at lower frequency . The latter approach using discrete masses or known as vibration neutralizers, however, is more sound because it does not contribute significant additional vibration energy to the structure, plus proven to yield substantial attenuation in structural vibration [6, 14]. Fig. 1 illustrates the application of vibration neutralizer which comprises of mass, spring and damper attached to a machine.