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The localization of shaking forces acting on an operating machine is an important step to identify vibration and noise sources. The forced vibration response of a linearly vibrating structure is assumed to be linear. However, the energy distribution of a linearly vibrating structure contains “coupled terms” in the modal decomposition of the vibration energy density function. These coupled energy terms represent the cross-modal energy density associated with the exciting force of a dynamic structure under forced vibration. In this research, it is proved analytically that the high-order cross-modal energy densities of a linear dynamic structure are highly correlated to the location of the external exciting force. Using this finding, a new force localization index based on the high-order cross-modal energy densities of a dynamic structure is proposed and tested. Numerical tests on uniform and step beam structures under force excitation with different frequencies and locations have been carried out to test the effectiveness of the proposed force localization method. It is found that the proposed force localization method works well on vibrating beam structures. Experiments are carried out to verify the proposed force localization method.

Annoyance caused by railway operations has gained increasing attention in the Netherlands. This has led to a multimillion research project into different aspects of train passages as a source of vibration. The project is initiated by the Dutch railway operator ProRail. In advance of this project a study has been performed on vibration signals at free field caused by cargo train passages at four different sites. The signals have been compared to trackside measurements. The trackside measurements consist of fibre optic measurements of the rail deflection at pre-installed locations different from the free field vibration measurement sites. Different vibration level indicators have been studied like train speed, axle loads and wheel roughness indicators and their correlation with vibration levels. Vibration levels are defined in several ways, a frequency weighted running mean square value (so-called Veffmax), a 2-second RMS level (unweighted) and levels per frequency band. Special attention is given to the variation in time of the measured vibration signals during the train passage to see whether 'bad quality' wheel passages can be identified. The results give valuable input for a future case study in which wheel quality and its influence on vibration levels will be studied further.

Creation of downhole sources of elastic vibrations for the implementation of vibrowave enhanced oil recovery methods is an urgent task of mining engineering. The paper substantiates the expediency of using an electromagnetic linear drive of a downhole vibration source to generate axial shock pulses. A mathematical model is proposed that describes the dynamics of movement of the striker of electromagnetic impact unit under the action of traction forces of coils, friction forces and aerodynamic resistance, taking into account the elastic constraints at the end of the lower and upper working strokes of the striker. Theoretical dependences of striker displacement and speed on time, obtained using the developed model, are presented, and their high convergence with the experimental data is shown. The mathematical model of electromagnetic impact unit can be used to optimize its parameters, as well as to design new standard sizes of vibration sources that meet the requirements of the oil and gas industry.

There are some studies in the literature in order to make the interpretation of human tissues having different characteristics. Some of these studies focused on the evaluation of human face tissues. Vibration signals generated from vocal cords have been used in these studies about human face tissues. However, any study using the vibration signals recorded by applying the external vibration source having fixed frequency value is not available in the literature. In this study, it is aimed to investigate the frequency characteristics of the vibration signals recorded from the human face. These signals obtained from nine different regions on the faces of subjects are analysed using frequency characteristics. In the analysis stage, median and maximum frequency values are calculated and evaluated. So, the softness and hardness interpretation about these regions on the face can be made and the frequency ranges of these regions can be determined. As a result, it is observed that low-frequency signals are dominant in hard regions and high-frequency signals are dominant in soft regions.

Protecting sensitive and/or valuable facilities is of concern when placing them near a machine foundation. There are methods available and well-studied such as wave barriers to reduce tran...

The article is devoted to the study of the vibrational waves propagation and the estimation of the level of their influence on various objects. The development of adequate mathematical models, methods for the estimation of vibration wave levels at various distances from the earth foundation is an urgent task. In this article, a mathematical model was developed using a variational approach to study the propagation of vibration waves induced by railway transport at various distances. A technique for solving the considered problems was developed using the finite element method. The effect of the level of vibrations propagating from the railway transport motion on buildings located at a certain distance from the vibration source was investigated, when the railroad bed is located at the foundation level or at a certain height from the foundation. It was stated that if the railroad bed is located at a height of 2 m from the level of the earth foundation of the building, then the amplitude of vibration displacements in the building can be reduced from 1.5 to 3.5 times.

Vibration assessment criteria for cosmetic building damage are specified in terms of peak velocity thresholds. For masonry buildings, these thresholds are relatively low compared to vibration levels generated by various sources in the built environment. Therefore they will be exceeded numerous times over the lifetime of most buildings. These exceedances are important when one tries to establish or disprove a causal relation between building damage and a vibration source. Despite the relevance of this information, little is known about the number of times velocity thresholds for cosmetic building damage are exceeded in the built environment. The vibration data collected over a period of more than 5 years in 326 buildings, mostly constructed in masonry and randomly distributed over the Province of Groningen, allowed for a unique opportunity to gain insight. First of all, to determine the number of times these thresholds were exceeded, and secondly to make a comparison between shallow earthquakes and other sources. The number of exceedances and the return period were determined for a set of thresholds (i.e. 0.3, 1, 3, 5, 10, and 20 mm/s), which align with peak velocity thresholds typically encountered in vibration assessment guidelines and standards. The results obtained over a 1 year period with very low seismic activity (only earthquakes with M < 2.0) show that the velocity thresholds for cosmetic damage to masonry buildings (i.e. 1, 3, and 5 mm/s) were exceeded on average less than once a month for 80% of the building sensors. For buildings with a large number of exceedances of these thresholds, the most important sources appear to be traffic, construction work, and hits near the sensor. A subset of 59 building sensors was selected, for which the full operational period of about 5 years was analysed to determine the contribution of earthquakes to the threshold exceedances. Less than 1% of the 1 mm/s exceedances measured by the 59 sensors over their full operational period were caused by earthquakes. Only for building with few exceedances (less than 8), the relative influence of induced earthquakes on the number of exceedances is significant (between 30 and 50%).

We analyze temporal variations in the travel times of both P and S waves (Vp and Vs) for 14 months at Toyohashi (central Japan) with a continuously operating vibration source that could efficiently produce both P and S waves. Seismic waves produced by the source, which is called the accurately controlled routinely operated signal system (ACROSS), are recorded by three nearby seismic stations, and the travel time variation at each station is estimated using the transfer function calculated from the recorded data. Long-term variations in Vp and Vs are observed and can be interpreted by the change in fluid saturation and crack density of the subsurface rocks. The variation in fluid saturation and crack density are consistent with that in the groundwater level, which is measured at the station nearest to the ACROSS. Short-term responses to rainfalls are observed at the station nearest to the ACROSS system; the interpretation of the changes in crack density and saturation is inconsistent with the ground water observation, partly owing to the initial response to rainfall. This can be interpreted as an air–water mixture within pores or cracks on a fine scale.

Indonesia merupakan salah satu negara dengan gunungapi terbanyak di dunia. Rangkaian gunungapi membentang dari Pulau Sumatera, Jawa, Bali dan Nusa Tenggara. Dari kepulauan di Laut Bdana sampai bagian utara Pulau Sulawesi merupakan daerah gunungapi terpanjang di dunia. Indonesia memiliki 129 gunungapi aktif, 70 buah diantaranya berancaman dan 500 buah tidak aktif. Sejak tahun 1800, paling tidak telag tercatat 600 kali letusan oleh 70 gunungapi di Indonesia. Karena itu, Indonesia dapat dikatakan sebagai negara yang rawan bencana, terutama ancaman bencana gunung berapi. Pengamatan, pemantauan, pencatatan, penyebaran informasi dan peringatan tanda bahaya terhadap aktivitas gunungapi menjadi salah satu fokus dalam penanggulangan bencana gunungapi. Untuk mendukung hal tersebut diperlukan instrumentasi deteksi aktivitas vulkanik gunungapi. Salah satu instrumentasi yang digunakan untuk memantau aktivitas gunung berapi Gunung Merapi adalah Real-time Seismic Amplitude Measurement (RSAM). RSAM adalah sistem yang menyediakan pengukuran kontinu dari amplitudo seismik rata-rata absolut dari jumlah stasiun seismik. RSAM menempati peran strategis dalam memantau aktivitas seismik gunung berapi terutama pada saat krisis sebelum letusan. Dalam penelitian ini, perancangan sistem RSAM menggunakan sensor geophone untuk mendeteksi getaran seismik. Frekuensi tes yang diberikan dalam penelitian ini termasuk 10 Hz, 30 Hz, dan 50 Hz. Sistem yang telah dirancang bangun dapat mendeteksi frekuensi dengan baik sebagaimana dibuktikan bahwa semakin besar frekuensi uji maka semakin banyak output grafik yang dihasilkan. Selain itu, besaran yang dihasilkan juga semakin besar. Pada frekuensi 10 Hz, magnitudo yang dihasilkan adalah 0,997, pada 30 Hz magnitudo yang dihasilkan 1,559 sedangkan pada 50 Hz magnitudo yang dihasilkan adalah 1,962. Sistem RSAM yang dirancang bangun menghasilkan amplitudo yang memiliki hubungan linier dengan besarnya getaran sumber disediakan..

The challenges we are faced with in localizing objects are the complex environments, such as tunnels, high-rise areas and underground parking lots. This paper develops a bionic vibration source localization device to estimate the direction of the object which is inspired by the unique and precise hunting localization mechanism of scorpions. The localization device uses the sensor array, which is patterned after the scorpions’ biological sensory structure, and imitates the coding mode of scorpions’ sensory neurons for determination of the prey (vibration source) bearing. To verify the effectiveness of the localization device, some experiments were performed through real collected vibration signals. The Average Estimated Error (AEE) and the Relative Estimated Error (REE) of the experimental results were calculated to be 3.64° ± 2.44° and −1.43° ± 4.14°, respectively. It indicates that the device has a good performance to estimate the bearings of vibration sources at different distances and azimuths. This bionic localization device lays the foundation for the development of locating the moving object in some special conditions.

Due to the structural characteristics of railway turnouts, as well as their vulnerability to damage and other problems, the environmental vibrations induced by urban rail transit often have a greater effect on the railway turnouts than that on an ordinary line. Therefore, it is necessary to carry out an in-depth study on the characteristics of vibration source on the turnouts. In this paper, a group of representative turnouts is selected for field testing on four typical lines of different operational times in a Chinese city. The profile and rail irregularity of the turnouts are measured to evaluate the service condition of the turnouts and the wheel–rail interaction. The vibration acceleration of the track structure and tunnel wall is measured as the train passes the turnout by setting the measuring points in the two main vibration sources, including the switch and the crossing section. The time–frequency domain analysis method is used to analyze these data. It is found that the source strength of the tunnel wall in the crossing section is much greater than that in the switch section, and that the lateral vibration level is often greater than the vertical vibration level. Unexpectedly, there is a low positive correlation between the vibration level and the train speed, while the healthy state of the turnout rails has a great influence on the vibration level. According to the results of the research, the sources of vibration excitation in the turnouts are complex; therefore, it is necessary to comprehensively evaluate their environmental impact and take corresponding vibration control measures.

Vibrations propagating through the soil into the building can not only be harmful to the building structure or cause its accelerated wear, but can also effect on the vibrational comfort in the rooms. They can also be annoying for residents and building users, and in extreme cases can lead to sleep disorders, headaches and neurotic conditions. Especially vibrations from the low frequency range from 5 to 25 Hz are undesirable, because there are resonance frequencies of human internal organs in this frequency range. The human perception of vibrations in buildings, despite many researches made in the past, despite standards and requirements in this area, is still a topic not fully understood mainly due to the subjective nature of the perception of vibrations by various people. It is widely known that the type of transport vibration source has an impact on human perception. Vibrations generated by above-ground sources are more felt on the upper floors as opposed to vibrations generated from the underground. In this paper three types of transport vibrations are analyzed on one chosen building located in Warsaw. Human perception of vibration is evaluated according to two methods: root mean squared (RMS) and vibration dose value (VDV).

Harvesting energy from ambient vibration sources is challenging due to its low characteristic amplitude and frequencies. In this purpose, this work presents a compact hybrid vibration converter based on electromagnetic and magnetoelectric principles working for a frequency bandwidth and under real vibration source properties. The combination of especially these two principles is mainly due to the fact that both converters can use the same changes of the magnetic field for energy harvesting. The converter was investigated using finite element analysis and validated experimentally. Results have shown that a frequency bandwidth up to 12 Hz with a characteristic resonant frequency at 24 Hz and a power density of 0.11mW/cm3 can be reached.

When a high-power vibrating roller compact the subgrade, the vibration wave will quickly propagate along the surface of the subgrade and generate hazards to surrounding environment and structure. To study the vibration propagation rules of the roller, the vibration acceleration of the high-power vibrating roller was measured on the surface of the rock subgrade, coarse-grained soil subgrade and fine-grained soil subgrade. The respective relations between vibration acceleration and the distance from a vibration source in the vertical, horizontal radial and horizontal circumferential direction have been discovered. The research results show that the vibration peak frequency generated by the vibrating roller on the subgrade approximates vibration frequency. The vibration effective influence distance varies from 10m to14m, and the horizontal radial vibration is greater than that of vertical and horizontal circumferential direction. The vibration of the rock subgrade attenuates the most slowly and propagates the most remotely.

The tank vibration of power transformers comes from alternating forces acting on the core and windings. It is meaningful to study the vibration sources and the transmission characteristics in transformers for interpreting the constitution of the tank vibration specifically. This paper experimentally investigates the coupling between the winding vibration and the core vibration, as well as the vibration transmission characteristics on a single phase power transformer the winding vibration coupled with the core vibration has a broader frequency band than the responses caused by the electromagnetic force. For transmission characteristics, the oil-borne transmission is the main path for the winding vibration, while the structure-borne transmission highly depends on the modal characteristics of the tank. This work improves the understanding of the relationship between the internal vibrations and the tank responses.

Operational transfer path analysis is applied in this study to identify the vibration source and its critical transfer path. A simple analytical five-degrees-of-freedom mechanical isolation system is first taken as an example to illustrate the analysis flow and to validate the accuracy of operational transfer path analysis. The acceleration amplitude spectrum of the receiver is used to prove the accuracy, and the path contribution of each path is used to identify the critical path. Operational transfer path analysis is then applied to the cab mount system of a heavy commercial vehicle to identify the vibration source and its critical transfer path. The vibration energy propagation capabilities from the four cab mounts to the driver’s seat are analyzed by operational transfer path analysis with the path contribution analysis, and the maximum vibration source is identified by the path operation contribution analysis. The analysis and evaluation method of the operational transfer path analysis introduced in this study can provide a research foundation and reference for vibration or noise source identification in mechanical systems.

Offshore wind turbines (OWTs) are more and more widely used to produce electrical energy nowadays. Besides the constant wind and wave loads, earthquake excitation can be another important vibration source to the OWTs since many OWTs have been/will be constructed in the seismic prone areas. Extensive research works have been carried out to understand the dynamic behaviours of OWTs when they are subjected to multi-hazards (e.g. the simultaneous wind, wave and/or earthquake loadings). However, when seismic excitations are considered, the onshore earthquake records are normally used as inputs in the analyses due to the lack of offshore data and the difficulty in synthesizing the offshore seismic motions. This practice may lead to inaccurate structural response estimations since it is well known that the seawater can significantly suppress the seafloor vertical motions near the P wave resonant frequencies of the seawater layer, which in turn results in the different characteristics of onshore and offshore earthquake recordings. Moreover, the earthquake motions along the pile of OWTs are different from those at the ground surface, i.e. the earthquake motions vary with the soil depth. Recently, a method to stochastically simulate the earthquake ground motions on the offshore site was proposed, in which the influence of seawater layer was considered and the earthquake motions at any soil depth could be obtained. This paper carries out numerical simulations on the dynamic behaviours of OWTs subjected to the combined wind, wave and earthquake loadings, and the depth-varying offshore seismic motions are used as inputs in the analyses. The seismic responses of OWTs obtained from the onshore and offshore earthquake motions are calculated and compared. The influence of depth-varying ground motions on the dynamic responses of OWTs is discussed.

The movement and mechanical characteristics of oil-tea camellia fruit coupling with flower simultaneously during the harvest period were studied to provide an indispensable theoretical guideline for the mechanized picking machine. The mechanical properties of Camellia oleifera were obtained by investigating its flowers and fruits, and the vibration harvesting of Camellia oleifera was studied by using dynamic vibration device. The i-Speed3 high-speed camera was used to record the harvesting process, and the image analysis and calculation were carried out by its own Control-Pro software. The results showed that different varieties of Camellia oleifera had different flowering periods, ranging from 30 to 55 days; their weight also varied among varieties; there was no inevitable relationship between the binding force (pulling force and torque) of fruit stalks and their varieties, locations and diameter of fruit stalks. More importantly, during the vibration process, the fruit peeling speed is related to the vibration source clamping position and vibration parameters. Under the condition of short clamping distance and high frequency and low amplitude, the fruit is more likely to fall off.

Requirement of oil and gas industry in increasing of rate of hydrocarbon extraction from deposits contributes to development of science-based methods of oil production increasing. Vibrowave impact to productive seam is related to such methods. This impact can be effectively carried out with hole seismic signal sources. In the work results of study of load-bearing element of hole electro-magnetic pulse source are represented. Objective of the work is the study of static and dynamic strains of casing pipe, determination of values of pressure pulses at modified load-bearing element during its work with electro-magnetic striking center. Values of static and dynamic strains of casing pipe under the action of thrust force are experimentally determined. The values are located in flexible zone and make 1mm at the static load and from 0.35 up to 0.6mm at the pulse load. As the results of tests of vibration source prototype, dependence of pulse pressure value at load-bearing element on voltage of striking center supply under the pressure of preliminary pumping 20MPa is obtained. Pulse amplitude raises proportionally voltage in the range from 14.2 MPa up to 19.7 MPa. Experiments with increasing of pumping pressure in the range from 20 MPa up to 27 MPa have shown that ratio of pulse value to pumping pressure linearly reduces when voltage of striking center supply is constant. Obtained results are scientific basic for designing of load-bearing elements destined for work at pulse impact transfer mode.

The surface finish of ground workpieces often presents periodic marks related to different vibration frequencies. In some cases, however, the identification of the vibration source is not straightforward. Even low amplitude vibrations could create visually unacceptable surface waviness due to beating frequencies appearance. This paper introduces this phenomenon during the dressing process as an origin of the undesirable surface topography in grinding operations. The effect of dynamic and process parameters in this phenomenon has been analysed and a procedure to overcome the problem has been proposed. Finally, an experimental validation to demonstrate the validity of the methodology is shown.

The article describes a project proposed to determine the epicenter of a future short-focus earthquake tens of hours before and to reduce the magnitude of an impending catastrophic earthquake. It focuses on developing a physical model to determine the conditions necessary for the start of an earthquake, for a method based on the registration of flows of mercury vapor in the gas rising from the Earth. This model gives an explanation of why an earthquake precursor appears so early (such a long period of time can range from a few to hundreds of hours). Normally, the characteristic times of an earthquake precursor for seismic methods are tens of seconds. The project is based on the physical and mathematical models of an earthquake. The derived formula for the time of the precursor of a future earthquake allows us to explain and to describe the time increase for the precursor, depending on the magnitude of the earthquake. The method of reducing the magnitude of an impending catastrophic earthquake is based on the proposed physical model of the onset of an earthquake and is implemented by the action of a vibration source in the region of the detected earthquake epicenter. The proposed system should save citizens, lives from future short-focus earthquakes.

Operators of hand tractors are exposed to high levels of hand transmitted vibration (HTV). This vibration, which can be both irksome and hazardous to human health, is imparted to the operator via his or her hands and arms. However, a standardized method for measuring HTV of hand tractors has yet to be defined. The aim of the study was to present an experimental method for the investigation of the biodynamic response and vibration transmissibility of the hand-arm system during the operation of a hand tractor in a stationary mode. Measurements were performed with ten subjects using three grip forces and three handle vibration levels to examine the influences of the hand pressure and frequency on hand transmitted vibration (HTV). The results indicate that the tightness of grip on the handle influences the vibration response of the hand-arm system, especially at frequencies between 20 and 100 Hz. The transmission of lower frequencies in the hand-arm system was relatively unattenuated. In comparison, attenuation was found to be quite marked for higher frequencies during the operation of the hand tractor. The vibration transmissibility to different parts of the hand-arm system decreased with the increase of the distance from the vibration source. The proposed methodology contributes to the collection of consistent data for the evaluation of operator vibration exposure and the ergonomics development of hand tractors.

This study investigated the localization ability of an impulse vibration source outside the body in two-dimensional space. We tested whether humans can recognize the direction or distance of an impulse vibration source when using their hand to detect spatiotemporal vibrotactile information provided by the propagated vibrational wave from the source. Specifically, we had users put their hands on a silicone rubber sheet in several postures. We asked users to indicate the position of the vibration source when a location on the sheet was indented. Experimental results suggested that the direction of the impact vibration source can be recognized to some extent, although recognition accuracy depends on hand posture and the position of the vibration source. The best results were achieved when the fingers and palm were grounded and a vibration source was presented around the middle fingertip, and the directional recognition error in this case was 6 degree. In contrast, results suggest it is difficult to accurately recognize the distance of the vibration. The results of this study suggest a new possibility for directional display where vibrotactile actuators are embedded at a distance from the user's hand.

Background and Objective Chronic exposure to resonant environment may cause more serious injuries to human lumbar spine than other vibrations. On the condition that the natural frequency of human lumbar spine is known, excitation frequency from an external vibration source can be optimized to keep away from the natural frequency and thus avoid lumbar resonance. Therefore, this study aimed to present an approach to predict the natural frequency of the human lumbar spine. Methods Four poroelastic finite element models of human L2–L3 spinal motion segments with different degrees of degeneration were established. Dynamic finite element analyses of these models during 1 h of vibration were then conducted. The mechanical parameters of these models under vibrations at different excitation frequencies were predicted. The excitation frequencies that resulted in the greatest changes in the lumbar mechanical parameters were identified as the natural frequencies of the established L2–L3 spinal motion segments. Results Simulation results showed that the natural frequencies of the healthy and mildly degenerated L2–L3 spinal motion segments, moderately degenerated L2–L3 spinal motion segments, and seriously degenerated L2–L3 spinal motion segments were in the range of 5–7, 3–5, and 1–3 Hz, respectively. Conclusions The predicted results indicated that the natural frequencies of the human L2–L3 spinal motion segments gradually decreased with the severity of degeneration. These phenomena may be related to changes in the lumbar structures and materials because of degeneration. This study provided a feasible method to predict the lumbar natural frequencies for different populations, which may be helpful in optimizing external vibration sources to avoid lumbar resonance.

During a print, friction-induced vibration can occur in a toner fixing device of a recent copier and a printer. The toner fixing device comprises a fixing sleeve, a heat source, a pressure roller including an elastic layer, and a pad. The inner surface of the fixing sleeve slides on the pad. In some operational conditions, the uncomfortable noise occurs by friction-induced vibration. The purpose of this study is to clarify the generation mechanism of friction-induced vibration. The present study investigates the friction torque between the fixing sleeve and the pad and the main vibration sources experimentally. As a result of experiments, it was made clear that the noise is likely to occur in a region where the friction torque has a negative slope with respect to velocity. Further, it is clarified that the vibration mode of the fixing sleeve is the main vibration source of friction-induced vibration from the measurement of the actual operating vibration mode of the fixing sleeve and the pressure roller.

In order to improve the utilization rate of expensive and very limited urban land, a new structure system, underground metro depot, has been developed and applied in several cities in China. The underground metro depot, which is built underground, can be multiple stories, and allows other developments on top, has become increasingly popular in recent years. Since there are other developments on top, the vibration induced by the trains frequently entering and exiting the depot cannot be ignored. To better understand the characteristics of the train-induced vibration in the underground metro depot, a series of field tests were conducted on a two-story underground depot which is the largest underground metro depot in Asia. The results show that the main frequency components of vibration source are between 50 and 200 Hz and the level of that in the first floor underground is larger than that in the second floor underground due to the train floor structure interaction when the train running on the first floor underground. The vibration in the top platform decreases linearly with the distance from the measuring point to the center line of the track. When the train is running on the track at the edge area, the linear attenuation rate was about 0.2dB/m. It is easy to excite the vibration mode of the floor structure when the train is running on the first floor underground, so the vibration in the top platform induced by the train running on the first floor underground was much larger than the train running on the second floor underground. In the future design, if the underground depot has more than one floor, the structural dynamic behavior of over-track buildings induced by the train running on the floor slab underground should be the focus. The throat area has many rail joints and turnouts which can lead to a larger vibration level, the level easy to exceed the limit given for human vibration comfort. If developments are proposed on top of the throat area, the vibration level should be carefully checked in the area within 30 m from the track to avoid potential later vibration problem.

Machine-induced vibrations and their control represent, for several reasons, a crucial design issue for buildings, and especially for industrial facilities. A special attention is required, at the early design stage, for the structural and dynamic performance assessment of the load-bearing members, given that they should be optimally withstand potentially severe machinery operations. To this aim, however, the knowledge of the input vibration source is crucial. This paper investigates a case-study eyewear factory built in Italy during 2019 and characterized by various non-isolated computer numerical control (CNC) vertical machinery centers mounted on the inter-story floor. Accordingly, the structure started to suffer for pronounced resonance issues. Following the past experience, this paper reports on the efficiency of a coupled experimental-numerical method for generalized predictive and characterization studies. The advantage is that the machinery features are derived from on-site experiments on the equipment, as well as on the floor. The experimental outcomes are then assessed and integrated with the support of Finite Element (FE) numerical simulations, to explore the resonance performance of the floor. The predictability of marked resonance issues is thus analyzed, with respect to the reference performance indicators.

When the combat platform is running on the road at a constant speed, it will have different vibration responses due to the different speed and road roughness. Road excitation is the main vibration source of the vibration system of the combat platform. Obtaining accurate road information is the key to analyze and evaluate the impact of the combat platform system on the road. In this paper, based on the fitting expression of road power spectral density recommended by GB/T7031-2005 and Simulink simulation software, the simulation model of combat platform is established when it is moving, and then the time-domain response of 1/2 combat platform system dynamics model under road random excitation is analyzed. The influence of road roughness and running speed on the vibration response of platform body is analyzed. It provides a theoretical basis for the design and structure optimization of combat platform.

Metal structure workpieces (such as steel plates, aluminum plates, and composite plates, etc.) have some damage and defects during processing and use, so the health detection of metal plate structures is a necessary link in the project. Non-destructive testing technology based on elastic wave is a potential research direction. This method has the advantages of high efficiency, convenience, fastness, non-contact, and online detection when used to detect defects of metal components. In order to excite the elastic wave in the metal plate structure, this paper researchs and designs a super magnetostriction vibration source based on the magnetostriction effect. The goal of this paper is to manufacture an economical, convenient and excellent performance magnetostriction vibration source, so it’s signifanctant to carry out structural design, optimization and performance testing of the vibration source. Finally, experiments verify that the designed super magnetostriction vibration source can excite elastic waves in the metal plate structure.

With the rapid development of urbanization and industrialization in modern society, the large-scale integrated hub must meet the seamless connection of various modes of transportation, thus the railway undepassing the airport terminal has become the main choice for engineering construction scheme. When the train under passes the airport, the vibration due to the wheel-rail excitation will affect the airport office area, commercial area and passenger waiting room in the terminal. With consideration of vibration source system, transmission process and vibration receiving body, this paper established the vehicle-track coupled model and the tunnel-soil-surface building integrated coupled model respectively to analyze the vibration characteristics of railway underpassing airport terminal as well as the effect of the corresponding vibration isolation measures.

The paper aims to summarize a modern approach to design of new or optimization of the existing vibration technologies, respectively. The optimization method consists of several necessary phases, which need to take place with utmost precision. In the first phase, a study of the current state of the solved problem is carried out along with analysis of the used bulk material performed as a measurement of mechanical-physical properties. Furthermore, a model of a new structural solution is designed and subjected to a number of simulation experiments using the DEM method. The parameters obtained from the performed simulations are used for manufacturing the vibration separator prototype including the design of a suitable vibration source. Operational tests of the vibration separator are carried out followed by putting the technology into operation.

Summary The paper presents the results of mine seismic surveys of safety pillars at the Upper-Kama potash deposit. The orientation of vibration source at generation of waves into wall of mine working is considered. It is established that the direction of propagation of elastic waves of the P-type, in contrast to S-type waves, is characterized by a certain selectivity and corresponds to the direction of emission. The possibility of high-quality separation of P and S waves in digital data processing is shown. In case of lateral half-space transmission on reflected waves, structural and lithological features of the rock mass are distinguished due to joint analysis of seismic sections and their velocity characteristics.

The attention of this work is focused on the achievable dynamic responses, i.e., the sets of all possible frequency responses of system transfer functions with all possible proper rational stabilizing controllers, of general undamped mass-chain systems. The Youla parametrization is adopted to obtain all possible proper rational stabilizing controllers and all possible frequency spectrums of a transfer function of the general undamped mass-chain system according to different system measurements. Some conclusions are presented to show the relation of the achievable responses of a transfer function using different system measurements. The achievable dynamic responses of the transfer function from the vibration source to the top mass block using some two-feedback-signal measurements and the full-signal measurement are first obtained, from which the achievable dynamic disturbance responses of other transfer functions are then deduced. The conclusions, which are obtained in this work, explain some classical results of 2-degree-of-freedom undamped vibration systems, and generalizes these results into arbitrary n -degree-of-freedom undamped systems.

This paper investigates the responses of cohesive sediment to mechanical vibration by experimental observation, containing: (1) the dynamic soil pressure, dynamic pore water pressure and dynamic acceleration to the vibration source; (2) the soil pressure distribution in the near field centered in an artificial columnar vibration source. Under the mechanical vibration with a frequency of 200 Hz and an amplitude of 1.15 mm, the dynamic soil pressure, dynamic pore water pressure and dynamic acceleration of underwater viscous sediment were measured in the sediment of four different depositing conditions. Results of the dynamic soil pressure, dynamic pore water pressure and dynamic acceleration of underwater viscous sediment in the near field responding to artificial vibration source are exhibited and discussed. It is found that, excited by the sinusoidal vibrator, the soil pressure presents a response of statistical sinusoidal fluctuation with the same frequency to the vibration source. In the sediment of lower initial yield stresses, the soil pressure distribution distinctly tends to firstly increase and then decrease with distance. The amplitude of the soil pressure is attenuated exponentially with distance.

In the paper, modeling of the effect of road vibrations on displacements in the slide zone, taking into account impulse waves is presented. The analysis was carried out for an area in which landslide movements occurred in 2010. The analysis concerning the influence of the vibration source’s speed was carried out. The influence of the generated load on the values of vertical displacements created in the slide zone was analyzed. Loads from moving trucks have been included in the form of kinematic impact. Numerical simulations were carried out using a program based on the Finite Element Method.

Environmental ground vibrations induced by construction operations, machine foundations, vehicular and railway traffic may cause discomfort to the dwellers in their immediate vicinity and malfunctioning of sensitive equipment in nearby structures. Associated with technological development and rapid industrialization, undesired vibrations around the residential areas have increased. Hence, the isolation of those vibrations has become an important issue. Open trenches are mainly employed as wave barriers in mitigation of undesired vibrations. Recent studies have focused on the parameters affecting the vibration isolation performance of open and in-filled trenches. It is stated that screening effectiveness mainly depends on the type of the vibration source and geometric dimensions of open trenches along with the local site conditions. In the present study, a series of full-scale field experiments were conducted to identify the effects of governing parameters on efficiency. The amplitudes of ground vibrations, artificially generated on the site, were measured through highly sensitive accelerometers at different test configurations. It was concluded that the frequency of vibrations had more influence than the actual depth of the barrier on screening effectiveness. Better isolation can be achieved in a region close to the trench while the effectiveness decreases at great distances. In addition, the results were compared with those of recently reported in experimental studies.

This paper presents an advanced method of selecting the number of poles slots so as to reduce the vibration of a traction motor for a gearless elevator system. The vibration source, i.e., the radial electromagnetic force, of the prototype was examined through its analytical derivation. The expression indicated the vibration orders and frequencies of the radial electromagnetic force that was caused by the interactions within or between armature reaction and permanent magnet fields including the stator slotting effect. More specifically, the prototype with 14 poles and 18 slots displayed a problem in terms of the vibration at the two times line frequency; this was due to the lowest vibration order 2. The vibration at two times line frequency was decreased by approximately 77.27% through a selection of 24 poles and 54 slots with a lowest vibration order of 6. A tower test was then conducted in order to validate the proposed method. Finally, an experiment on models having other rated load and pole-slot combinations was also carried out to improve the overall reliability.

Vibrations exist widely in the ocean, and the one caused by sound and biological movement plays an important role in the sensory system of marine organisms. The vibration caused by sound has many characteristics that make it a good candidate for modifying the movements of marine organisms. However, few studies have tested whether hydraulic vibration caused by sound has effects on the migration of sea cucumbers, and this has never been systematically studied previously in Apostichopus japonicus (Selenka). In order to understand whether hydraulic vibration caused by sound at different frequencies could affect the migration of sea cucumbers, in the present study, hydraulic vibration caused by sound at various frequencies was tested in the laboratory to determine their effects on the migration of A. japonicus at different sizes. The mean probability distribution was used as a statistical index to demonstrate the moving tendencies of the species. The experimental results showed that medium and small A. japonicus (

The contribution deals about determination of vibration source and mechanical system by using Short Time Fourier Transformation. To understand the degradation mechanisms in a machine would be required to perform dynamic analysis to identify the source of vibration and their interactions. To excitation of measured object we used run-up and shut down expected rotational excitation source in the system. After performing the measurement has been carried out with determining the interaction between the natural frequencies of the system and excitation frequency. Since it was present for more than one excitation source, the effect of the first was characterized by the independent variable and the second excitation source as the measurement parameter. Based on the measurements can also be adjusted by controlling operating modes of the excitation source.

The density of high-rise building is increasing over recent years in urban city. Construction activities, particularly piling processes, D-wall excavation, are paid attention due to ground borne vibrations. The impact of construction-induced vibrations on existing buildings is discussed in the past and so on. However, the impact of some special source such as grab shocking the Metro Line 3 (Hanoi) hasnot beenmentioned in literature. This paper evaluates the potential effect of ground vibrations induced by grab shock on sensitive existing buildings through field experiences, alsothe analytical closed-form formulation of construction-induced vibrations on existing building in Hanoi is proposed. This formulation is applied to investigate the construction-induced vibrations on existing building in Metro Line 3 project. This application is useful to control the grab drop length as well as the distance of existing building to vibration source.

Different researches have been conducted in order to make the interpretation of tissues belonging to different individuals carrying different characteristics. These investigations are generally based on vibration signals. In the studies in the literature, the vibration signals that usually appear in the vocal cords during speech are examined. However, there is no study on vibration signals recorded by applying any vibration source. The investigation of the frequency characteristics of the vibration source which has a fixed frequency on the tissues is of great importance both for the information about the tissue and the investigation of the related diseases. In this study, it is aimed to design the user interface to measure the vibration signals taken from certain distances to the vibration source applying vibration at a constant frequency to the living tissues determined on the human face and to analyze these vibration signals. The first part of the equipment consists of a motor and a drive part that provides vibration. Another part consists of accelerometer sensors and drives in MEMs structure which enable the detection of vibrations at certain points of the face region. The control of the hardware is carried out with a microcontroller-based module. With the help of this designed device, it is thought that vibration signals from living tissues can help soft and hardness interpretation of related tissues and body conductivity interpretation of related tissues can be done in future studies.

In this study we propose a novel method for drone surveillance that can simultaneously analyze time-frequency responses in all pixels of a high-frame-rate video. The propellers of flying drones rotate at hundreds of Hz and their principal vibration frequency components are much higher than those of their background objects. To separate the pixels around a drone's propellers from its background, we utilize these time-series features for vibration source localization with pixel-level short-time Fourier transform (STFT). We verify the relationship between the number of taps in the STFT computation and the performance of our algorithm, including the execution time and the localization accuracy, by conducting experiments under various conditions, such as degraded appearance, weather, and defocused blur. The robustness of the proposed algorithm is also verified by localizing a flying multi-copter in real-time in an outdoor scenario.

In this paper, the methods of mathematical modeling investigate the possibility, under certain conditions, of the propagation of elastic waves in a block-fractured geological environment, generated by a source located on the surface, without significant scattering. A computational model has been created that includes a geological environment within which internal boundaries (cracks) can exist with different conjugation conditions on them (conditions of “complete sticking”, conditions of “slipping with friction”, etc.). On the surface, there is a permanently acting vibration source of elastic waves. The paper theoretically substantiates and implements the original computational algorithm for solving the initial-boundary value problem, based on the construction of a fundamental solution of the problem operator. The algorithm showed high efficiency and allowed to conduct a series of resource-intensive experiments. The carried out computational experiments showed that if the slip conditions are realized at the internal boundaries, then the elastic wave propagates in the channel between these cracks, almost not penetrating beyond their limits. The relationship between the nature of the propagation of elastic waves and the frequency of the vibration source is tested. It is shown that with an increase in the frequency of the vibration source operation, the degree of penetration of elastic waves beyond the channel boundaries determined by cracks increases. And at sufficiently high frequencies, the wave pattern becomes similar to what is happening in a continuous medium.

It has been reported that ultrasonic welding using planar vibrations results in higher weld strength and less damage to the work pieces compared with ultrasonic welding using linear vibrations. However, torsional vibration transducers are small and expensive, thus reducing flexibility in the use of the vibration source. Therefore, in this study, we developed an ultrasonic longitudinal-torsional vibration source using longitudinal vibration transducers and a uniform rod with diagonal slits. The proposed vibration source generates torsional vibration by using a uniform rod with diagonal slits instead of a conventional torsional vibration transducer. As a result, it is found that a planar vibration locus is obtained by inputting two resonance frequencies simultaneously.

We design a kind of vertical vibration experiment bench with small vibration source and large load, and demonstrate that the support spring has no influence on the vibration transmissibility. The spring parameters are designed based on the resonance characteristic of the spring, and the transfer plate is simulated and optimized by Workbench and Hyperworks. The experiment bench makes the large load can be vibrated under the excitation of small vibration source, which provides a reference design for the vibration isolator and other equipment that need to carry out the large load vibration experiment.

Vibrations during the fermentation of yogurt and related milk products have recently been reported to disturb the gelation and result in quality defects such as particle formation, graininess, and syneresis. However, primary research on this topic was focused on experiments performed on a laboratory and pilot-plant scale. In this study, three large dairy factories were visited, and yogurt samples were directly taken out of various fermentation tanks, showing great differences in terms of graininess and particle content. Thereupon, vibration measurements were conducted at three industrial yogurt plants. Particularly, pumps and their influence on the vibrational excitation of the fermentation tanks were examined. The major structural and mechanical differences of these plants, such as distances between the vibration source and the tank or the types of pumps used, led to varying vibrational states at the fermentation tanks. We concluded that the vibrational excitation of each plant must be evaluated individually in order to estimate the potential for vibration-induced texture defects.