Airborne Vibrations Research Articles

Biomechanical properties of non-flight vibrations produced by bees.

Bees use thoracic vibrations produced by their indirect flight muscles for powering wingbeats in flight, but also during mating, pollination, defence and nest building. Previous work on non-flight vibrations has mostly focused on acoustic (airborne vibrations) and spectral properties (frequency domain). However, mechanical properties such as the vibration's acceleration amplitude are important in some behaviours, e.g. during buzz pollination, where higher amplitude vibrations remove more pollen from flowers. Bee vibrations have been studied in only a handful of species and we know very little about how they vary among species. In this study, we conducted the largest survey to date of the biomechanical properties of non-flight bee buzzes. We focused on defence buzzes as they can be induced experimentally and provide a common currency to compare among taxa. We analysed 15,000 buzzes produced by 306 individuals in 65 species and six families from Mexico, Scotland and Australia. We found a strong association between body size and the acceleration amplitude of bee buzzes. Comparison of genera that buzz-pollinate and those that do not suggests that buzz-pollinating bees produce vibrations with higher acceleration amplitude. We found no relationship between bee size and the fundamental frequency of defence buzzes. Although our results suggest that body size is a major determinant of the amplitude of non-flight vibrations, we also observed considerable variation in vibration properties among bees of equivalent size and even within individuals. Both morphology and behaviour thus affect the biomechanical properties of non-flight buzzes.

Calibration technique for airborne vibration sensors based on actuators

Addressing the challenge of in-situ calibration for onboard vibration sensors in aircraft installations, we propose an online calibration method based on actuators. Leveraging the inverse piezoelectric effect, we employ piezoelectric actuators mounted on the vibration sensors to calibrate vibration signals. Experimental results demonstrate that the influence of the actuator on the energy transfer of the measured sensor’s vibration signal during the calibration process can be negligible, meeting the calibration accuracy requirements of onboard vibration sensors. Through validation experiments, we determine the excitation coefficients of the actuators at different frequencies, subsequently obtaining the sensitivity of the vibration sensors equipped with actuators. The results reveal that within the frequency range, the relative error of sensitivity remains within ±3%, satisfying the relevant calibration requirements. Therefore, the actuator-based online calibration technique offers an efficient means of calibrating onboard vibration sensors, carrying significant practical value.

RF-Mic

Eavesdropping on human voice is one of the most common but harmful threats to personal privacy. Glasses are in direct contact with human face, which could sense facial motions when users speak, so human speech contents could be inferred by sensing the movements of glasses. In this paper, we present a live voice eavesdropping method, RF-Mic, which utilizes common glasses attached with a low-cost RFID tag to sense subtle facial speech dynamics for inferring possible voice contents. When a user with a glasses, which is attached an RFID tag on the glass bridge, is speaking, RF-Mic first collects RF signals through forward propagation and backscattering. Then, body motion interference is eliminated from the collected RF signals through a proposed Conditional Denoising AutoEncoder (CDAE) network. Next, RF-Mic extracts three kinds of facial speech dynamic features (i.e., facial movements, bone-borne vibrations, and airborne vibrations) by designing three different deep-learning models. Based on the extracted features, a facial speech dynamics model is constructed for live voice eavesdropping. Extensive experiments in different real environments demonstrate that RF-Mic can achieve robust and accurate human live voice eavesdropping.

Data-Driven Electrical Machines Structural Model Using the Vibration Synthesis Method

This article proposes a data-driven structural modeling approach for electrical machine airborne vibration that can be used both in the design stage for fast optimization routines and in system-level simulations. This method is able to capture both in-plane and out-of-plane modal behavior along with local effects, such as tooth bending. The model relies on fitting unitary force-shape responses to transfer function models using a zero-pole representation. These frequency response functions are obtained from applying the vibration synthesis process to a series of finite-element (FE) stator models that have material properties updated using the experimental modal analysis. The obtained zeros and poles are used to construct three lookup table models with their accuracy varying between the three of them with the number of samples used in the data generation process. The accuracy of these models is validated at the unitary force-shape response level using four stator FE model samples. Also, at the run-up vibration spectrogram level, the models are validated, with good results, using radial and tangential force excitation obtained from an updated electromagnetic FE model of an interior permanent magnet (PM) synchronous machine designed for electric power steering. The computational cost compared to the standard FE vibration synthesis method is shown.

Implementation of Tension-Based Compact Necklace-Type Haptic Device Achieving Widespread Transmission of Low-Frequency Vibrations

The haptic sensation of low-frequency vibration plays a vital role in the music listening experience, but it can be enjoyed only in certain facilities and environments. Many haptic devices have been proposed to convey music audio-induced vibration for various situations. Such devices require powerful, low-frequency vibration output and transmission over a wide area. Making such devices small and user-friendly is difficult, hindering their popularity. To promote haptic devices for music listening, this paper describes a method for developing a practical device using motors and a thread and evaluates this method's effectiveness. The proposed necklace-type device is small (about 55 × 58 × 15 mm), lightweight (58.5 g), and easy to wear, making it suitable for use during everyday travel. In addition, it can transmit low-frequency (20 Hz) vibrations, whose amplitude exceeds airborne vibration in a nightclub, to a wide area across the chest and neck, with a total power consumption of approximately 2 W. Our proposed method will contribute to the development of practical and high-performance haptic devices for music listening.

Noise Reduction by Rail Damper Tunable for Individual Rails in Curve

Tuned mass rail dampers are cost effective for the mitigation of the airborne noise and vibration with the ability to be tuned for individual site. TMDs have been developed and installed at a single rail in a curve tunnel and achieve more than 4dB(A) noise reduction in many cases. According to the on-site noise reduction performance during damper installation, half, one, two or three dampers can be installed at each spacing between two baseplates. TMDs with only half-installation provides more than 10dB reduction at vertical pin-pin resonance (~1kHz). With the standard installation, they provide the strong damping to half the corrugation growth rate. The stick-slip phenomena which causes the corrugation will be affected by the damping effect from TMDs. On the other hand, they can also be tuned to the low-frequency (p2 resonance) for grandborne noise control. The high reduction of the grand borne noise proved our claim for effectiveness of the TMDs besides many other studies on the other parameters like the type of the baseplates or the soil types. According to the test results TMDs achieve strong performance in different range of the frequencies.

Sound Transmission between Rooms with Curtain Wall Façades: A Case Study

Curtain walls have reached good performances in terms of façade sound and thermal insulation, as well as solar protection. Nevertheless, the sound insulation performance of the partition between adjoining rooms with continuous curtain wall façades is often reduced by the presence of direct and flanking transmission through the junction with the façade itself. In this work, flanking and direct structural transmissions are analysed with reference to the joints of the mullion of the curtain wall with lightweight plasterboard partitions. Airborne sound insulation and vibration measurements were made in two adjacent rooms affected by the acoustic problems determined by the curtain wall joint. Traditional acoustic measurements, carried out according to EN ISO 16283–1, highlighted problems in sound insulation between rooms, but without any indication on different sound transmission paths through the wall. Vibration measurements were made for every part of the system (frame columns and beams, window panes, plasterboard wall, plasterboard false ceiling, etc.) to better understand the sound transmission paths in these kinds of structures. In this paper the results of this analysis are presented. Moreover, taking into account previous works and measurements made in this research field, different solutions for curtain wall structures are analysed and technical suggestions are given to improve airborne sound insulation between rooms separated by partitions mounted up to metal frames.

全景式航空相机图像拖影与扭曲补偿系统研究

In panoramic aerial camera pendulum sweep imaging process, the dithery scanning mirror position caused by the incomplete isolation of airborne vibration environment, causes a shaking of the visual axis, which makes the image in the sweep direction produce distortion and smear. Aiming at the above problem, the geometric model is established among flight speed, altitude, target level angle and pitching axis speed compensation, with which the causes of the disturbances of image distortion and the influence of compensation precision on image smear pitching axis degree are analyzed. Through the model establishment and parameter analysis, the pitching axis control system dynamics and steady-state performance and robustness requirements are obtained. Laboratory dynamic target generator and parallel light pipe model are used to simulate the relative movement between camera and objects so as to test the precision of the control system. The exterior image in the vibration surroundings is used to test the disturbance compensation performance of the control system. Experiment results show that the steady speed error of pitching axis control system is less than 0.005/s, that almost completely suppresses the image smear phenomenon; the speed compensation residual error under 7 Hz disturbance signal is less than 0.1/s, and the system can effectively compensate the disturbance caused by the image distortions.

Sensors and sensory processing for airborne vibrations in silk moths and honeybees.

Insects use airborne vibrations caused by their own movements to control their behaviors and produce airborne vibrations to communicate with conspecific mates. In this review, I use two examples to introduce how insects use airborne vibrations to accurately control behavior or for communication. The first example is vibration-sensitive sensilla along the wing margin that stabilize wingbeat frequency. There are two specialized sensors along the wing margin for detecting the airborne vibration caused by wingbeats. The response properties of these sensors suggest that each sensor plays a different role in the control of wingbeats. The second example is Johnston's organ that contributes to regulating flying speed and perceiving vector information about food sources to hive-mates. There are parallel vibration processing pathways in the central nervous system related with these behaviors, flight and communication. Both examples indicate that the frequency of airborne vibration are filtered on the sensory level and that on the central nervous system level, the extracted vibration signals are integrated with other sensory signals for executing quick adaptive motor response.

Morphological analysis of the primary center receiving spatial information transferred by the waggle dance of honeybees

The waggle dancers of honeybees encodes roughly the distance and direction to the food source as the duration of the waggle phase and the body angle during the waggle phase. It is believed that hive-mates detect airborne vibrations produced during the waggle phase to acquire distance information and simultaneously detect the body axis during the waggle phase to acquire direction information. It has been further proposed that the orientation of the body axis on the vertical comb is detected by neck hairs (NHs) on the prosternal organ. The afferents of the NHs project into the prothoracic and mesothoracic ganglia and the dorsal subesophageal ganglion (dSEG). This study demonstrates somatotopic organization within the dSEG of the central projections of the mechanosensory neurons of the NHs. The terminals of the NH afferents in dSEG are in close apposition to those of Johnston's organ (JO) afferents. The sensory axons of both terminate in a region posterior to the crossing of the ventral intermediate tract (VIT) and the maxillary dorsal commissures I and III (MxDCI, III) in the subesophageal ganglion. These features of the terminal areas of the NH and JO afferents are common to the worker, drone, and queen castes of honeybees. Analysis of the spatial relationship between the NH neurons and the morphologically and physiologically characterized vibration-sensitive interneurons DL-Int-1 and DL-Int-2 demonstrated that several branches of DL-Int-1 are in close proximity to the central projection of the mechanosensory neurons of the NHs in the dSEG.

The effect of predation risk on spider’s decisions on web-site relocation

Among the costs associated with animal-built structures, the cost of exposure to predators is important, because it affects the survival of builder animals. When predator risk increases, the builder may change the location of a structure or remain on the structure but modify its behaviour. The main purpose of this study was to examine whether builders leave their current structure locations and relocate to a new location upon predator attacks. To assess this, we used orb-web spiders that regularly renew their webs and occasionally relocates their web site upon web-rebuilding. Specifically, adult females of Cyclosa argenteoalba were exposed to the air-borne vibrations from a tuning fork. These vibrations simulate the vibrations from insect predators’ wings and trigger immediate anti-predator responses (jumping off the web to avoid attacks from predators and shaking webs). Spiders that received these simulated predator stimuli relocated more often on the day after treatment than did spiders that were not exposed to predator stimuli. This indicated that spiders estimated future predation risk from their predator-encounter experience and responded to perceived increase in predation risk at current site by abandoning their web site upon web-rebuilding. In addition, we examined whether the frequency of jumping behaviour and web relocation were correlated, but no significant relationship was detected. This result suggests that immediate anti-predator behaviour at the current site and the decision to relocate were independent of each other.

Stridulation byJadera haematoloma(Hemiptera: Rhopalidae): Production Mechanism and Associated Behaviors

AbstractThe Hemiptera displays a notable diversity of vibratory communication signals across its various families. Here we describe the substrate and airborne vibrations (sounds), the mechanism of production, and associated behaviors of Jadera haematoloma Herrich-Schaeffer, a member of the family Rhopalidae. Adult males and females both produce short, stereotyped sound bursts by anterior-posterior movement of abdominal tergites I and II against a stridulitrum located on the ventral surface of the metathoracic wing. Sound bursts are produced by a single adult male or female when physically touched by another adult, and are strongly associated with being crawled on by the approaching individual, but are not produced in response to contact with other arthropods or when pinched with forceps. The propensity to produce sounds when crawled upon decreases during the mating season. These sound bursts by J. haematoloma likely are communication signals. Rhopalidae has been significantly absent from the vibratory communication literature until now. Although the sounds are produced using a mechanism common to vibratory communication systems in closely related Heteropteran Hemiptera, the sounds in these other species function primarily in courtship or in mother-daughter interactions, which suggests that the functions of stridulation and the behavioral contexts have diversified in the Heteroptera.

Antennal sensory structures in Scaphoideus titanus ball (Hemiptera: Cicadellidae)

Scaphoideus titanus Ball (Hemiptera: Cicadomorpha) is a leafhopper vector of a phytoplasma disease, the Flavescence dorée (FD), belonging to the vine yellows group. A scanning and transmission electron microscope study has been carried out to investigate the antennal sensory structures. The first two segments, the scape and the pedicel, are short, covered by cuticular scales and devoid of sensilla, with exception of some scattered hairs on the pedicel. The flagellum consists of a unique, elongated segment in which numerous subunits can be recognized, being separated by a sort of cuticular crown. The proximal five subunits bear most of the sensilla. We discovered the presence of single- and double-walled coeloconic sensilla, campaniform sensilla, basiconic sensilla, and trichoid sensilla. A scolopidium is located within the proximal region of the flagellum. Ultrastructural investigations suggest that the antennal sensilla could be involved in the perception of air-borne vibrations, temperature, and humidity variations. The most relevant feature is the extreme reduction of the olfactory sensilla, both in terms of number of sensory structures and sensory neurons per sensillum. The strong reduction in antennal olfactory sensilla to which this specie has undergone is discussed as possible consequence of the specificity toward the host plant.

Active Process Mediates Species-Specific Tuning of Drosophila Ears

The courtship behavior of Drosophilid flies has served as a long-standing model for studying the bases of animal communication. During courtship, male flies flap their wings to send a complex pattern of airborne vibrations to the antennal ears of the females. These "courtship songs" differ in their spectrotemporal composition across species and are considered a crucial component of the flies' premating barrier. However, whether the species-specific differences in song structure are also reflected in the receivers of this communication system, i.e., the flies' antennal ears, has remained unexplored. Here we show for seven members of the melanogaster species group that (1) their ears are mechanically tuned to different best frequencies, (2) the ears' best frequencies correlate with high-frequency pulses of the conspecific courtship songs, and (3) the species-specific tuning relies on amplificatory mechanical feedback from the flies' auditory neurons. As a result of its level-dependent nature, the active mechanical feedback amplification is particularly useful for the detection of small stimuli, such as conspecific song pulses, and becomes negligible for sensing larger stimuli, such as the flies' own wingbeat during flight.

African tick-bite fever: a new entity in the differential diagnosis of multiple eschars in travelers. Description of five cases imported from South Africa to Switzerland

African tick-bite fever (ATBF) is a newly described spotted fever rickettsiosis that frequently presents with multiple eschars in travelers returning from sub-Saharan Africa and, to a lesser extent, from the West Indies. It is caused by the bite of an infected Amblyomma tick, whose hunting habits explain the typical presence of multiple inoculation skin lesions and the occurrence of clustered cases. The etiological agent of ATBF is Rickettsia africae, an emerging tick-borne pathogenic bacterium. We describe herein a cluster of five cases of ATBF occurring in Swiss travelers returning from South Africa. The co-incidental infections in these five patients and the presence of multiple inoculation eschars, two features pathognomonic of this rickettsial disease, suggested the diagnosis of ATBF. Indeed, the presence of at least one inoculation eschar is observed in 53-100% of cases and multiple eschars in 21-54%. Two patients presented regional lymphadenitis and one a mild local lymphangitis. Though a cutaneous rash is described in 15-46% of cases, no rash was observed in our series. ATBF was confirmed by serology. Thus, ATBF has recently emerged as one of the most important causes of flu-like illness in travelers returning from Southern Africa. The presence of one or multiple eschars of inoculation is an important clinical clue to the diagnosis. It can be confirmed by serology or by PCR of a biopsy of the eschar. Culture can also be done in reference laboratories. Dermatologists and primary care physicians should know this clinical entity, since an inexpensive and efficient treatment is available.

The sensory structures of the antennal flagellum in Hyalesthes obsoletus (Hemiptera: Fulgoromorpha: Cixiidae): A functional reduction?

Despite their relevance as harmful pests on plants of economic importance, Hemiptera Fulgoromorpha have been poorly studied as regards their antennal sensory structures. In particular, the flagellum has been neglected and, therefore, to date there are no data on its structural organization and sensory equipment. In order to fill this gap, we carried out a study on the sensillum types and distribution on the flagellum of the planthopper Hyalesthes obsoletus Signoret, an efficient vector of the stolbur phytoplasma, the cause of various crop diseases. In this cixiid species the antenna is composed of three segments, the scape, an enlarged pedicel and a long flagellum. This latter is made of a single segment and presents a basal, bulb-like enlargement from which two processes arise, a short spur and a long arista. Combining scanning electron microscopy, transmission electron microscopy and focused ion beam investigations, we discovered the presence of a total number of 6 sensilla, belonging to 4 different types: a single scolopidium extending from the bulb to the arista, three sensilla styloconica within the cuticular spur and two different sensilla coeloconica inside the bulb. As far as structural data can suggest, these sensilla might be involved in the perception of mechanical stimuli (possibly air-borne vibrations), temperature and humidity variations and CO 2 concentration. The strong reduction in sensillum number in this species is discussed as possible functional specialization of the flagellum itself. The ultrastructure of the sensilla in the flagellum of a species of Fulgoromorpha is here presented for the first time.

Response characteristics of vibration‐sensitive interneurons related to Johnston's organ in the honeybee, Apis mellifera

Honeybees detect airborne vibration by means of Johnston's organ (JO), located in the pedicel of each antenna. In this study we identified two types of vibration-sensitive interneurons with arborizations in the primary sensory area of the JO, namely, the dorsal lobe-interneuron 1 (DL-Int-1) and dorsal lobe-interneuron 2 (DL-Int-2) using intracellular recordings combined with intracellular staining. For visualizing overlapping areas between the JO sensory terminals and the branches of these identified interneurons, the three-dimensional images of the individual neurons were registered into the standard atlas of the honeybee brain (Brandt et al. [2005] J Comp Neurol 492:1-19). Both DL-Int-1 and DL-Int-2 overlapped with the central terminal area of receptor neurons of the JO in the DL. For DL-Int-1 an on-off phasic excitation was elicited by vibrational stimuli applied to the JO when the spontaneous spike frequency was low, whereas tonic inhibition was induced when it was high. Moreover, current injection into a DL-Int-1 led to changes of the response pattern from on-off phasic excitation to tonic inhibition, in response to the vibratory stimulation. Although the vibration usually induced on-off phasic excitation in DL-Int-1, vibration applied immediately after odor stimulation induced tonic inhibition in it. DL-Int-2 responded to vibration stimuli applied to the JO by a tonic burst and were most sensitive to 265 Hz vibration, which is coincident with the strongest frequency of airborne vibrations arising during the waggle dance. These results suggest that DL-Int-1 and DL-Int-2 are related to coding of the duration of the vibration as sensed by the JO.

Wave barrier of lime–cement columns against train-induced ground-borne vibrations

This paper presents a comparison between measured train-induced ground vibrations in the free-field before and after countermeasures had been taken at Kåhög near Gothenburg in Sweden. A wave barrier of lime–cement columns was constructed parallel to the railway in order to reduce the ground-borne vibrations inside nearby buildings. On top of the barrier an embankment was built to reduce air-borne vibrations. Due to the wave barrier design, part of the energy content of the waves was expected to be reflected by the screen and transmitted energy was expected to be partly scattered. Contribution from the noise-embankment was not thought likely but could not be ruled out due to its fairly large mass and its close proximity to the railway. The effect of the mitigating measures resulted in a 67% reduction of the maximum particle velocity at 30 m and 41% at 60 m from the railway. A simple two-dimensional finite element model has been used to study the relative importance of the wave barrier and the noise-embankment as contributors to the mitigation recorded of the ground vibrations in the field. It is concluded with respect to ground vibrations that both the barrier and the embankment had a mitigating effect but that the contribution from the barrier dominated. Furthermore, it is seen from the field results as well as the simulation that the effect of the mitigating action is reduced with increasing distance from the railway.

Spiders Use Airborne Cues to Respond to Flying Insect Predators by Building Orb-Web with Fewer Silk Thread and Larger Silk Decorations

Orb-web spiders are an important group of trap-building animals that feed upon an array of insect prey and are themselves the prey of wasps and parasitoid flies. The purpose of this study was to examine whether spiders use airborne vibration cues to respond to these flying insect predators by changing their web-building behavior. While on its web waiting for prey, the orb-web spider Eriophora sagana was exposed to a vibrating tuning fork that emitted an airborne vibration signal. The signal mimicked the approach of flying insect predators and its effect on the subsequent web building was examined. No stimulus was provided during web building. A significant treatment effect was observed with respect to the total thread length (TTL) and area of the silk decoration (conspicuous white structure attached to the orb-webs of diurnal spiders) of their webs. While control spiders increased the TTL in their second web, the stimulus group spiders did not, providing the first evidence that orb-web spiders use airborne vibration cues to assess the predation risk and change their foraging activity. It also indicates that spiders remember an encounter with a predator on their webs and use this information later to adjust their web building. My findings imply that spiders devote less effort to foraging (i.e. web building) in response to the presence of their predators, which is considered to reduce their foraging efficiency. In contrast, the stimulus group spiders increased the area of their silk decoration significantly more in their second webs than did the control spiders. This is considered an experimental support for the hypothesis that silk decorations have an anti-predator function.

On the Dispersal of Males of Cicada orni in Portugal (Hemiptera: Cicadidae)

Males of Cicada orni Linnaeus 1758 communicate through airborne vibrations producing calling songs, sometimes aggregating at high densities and exhibiting chorus activity. Previous work suggested that males were induced to sing when nearby conspecific males were calling, this resulting in male concentrations and also in poor dispersal ability. The present paper is an introductory investigation of the range of dispersal of the adults in this species, following a mark-recapture method, as well as of the length of adult life. Results show that at the site of the experiment - Sousel (southern Portugal) - the peak of adult emergence occurred before the 23 rd of June in 2006. Males of this species can survive for about two weeks, but most of them probably live less than a week. Moreover, almost 90% of the males fly less than 100 m and none was found to disperse beyond 150 m. Present results provide evidence that young males are maximizing their chances of mating by a strong singing activity without pre-mating dispersal. Therefore, it is likely that these cicadas do not disperse far to mate and that both sexes probably mate relatively close to the place where they have emerged.