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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...

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%).

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.

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.

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.

Arachnids including sand scorpions and spiders use their tactile sense organs, called basitarsal compound slit sensilla (BCSS), to detect their prey. The sense organs consisting of mechanoreceptors are located at or near joints in the cuticle, and they can sense a vibrational signal caused by prey movement. The nocturnal sand scorpion Paruroctonus mesaensis has a distinguished capability of finding their prey only with these tactile senses. The sand scorpions show their orientation behaviour of positioning themselves directly towards their prey and then run into the prey when there is a vibration disturbance caused by the prey. According to the biological researches (Brownell & Farley, 1979, Brownell, 1984), it is presumed that the sand scorpions respond to Rayleigh waves, surface waves of sand, to detect the direction of a vibration source and possibly longitudinal vibrations to estimate the distance. Especially, the time delay between arrival of a vibration signal at the BCSS sense organs is an important cue to determine the direction of their prey (Brownell & Farley, 1979). The central nervous system should process stimulus-locked neuron firings of the sense organs on their eight legs to induce the orientation behaviour. How the nervous system is organized to handle the orientation behaviour is still an open question. Only a few studies explain this behaviour mechanism. Stuerzl et al. (2000) introduced a neuronal mechanism to support the orientation behaviour of scorpions, and it is based on the difference of the arrival time of stimulus signals produced at sense organs on their legs. They argued that the brain of sand scorpions receives sensor signals from mechanoreceptors on their eight legs and processes an inhibition mechanism among a set of command neurons projected from the sense organs on each leg. This inhibitory interaction leads to more accumulated firings of the command neurons near the prey source and less firings at the opposite sides. The accumulated neuron firings thus form a tuning curve for a specific resource direction. Then the distribution of neuron firings can vote to determine the resource direction. In fact, arachnids have sensory projections to the central nervous system for each leg (Babu & Barth, 1989, Anton & Barth, 1993). Previously Brownell and Farley (1979) suggested that eight command neurons (or eight clusters of neurons in the brain) accumulate neuron firings from mechanoreceptors on the eight legs of scorpions, respectively and also interact each other with triad inhibitions. According to the triad inhibition hypothesis, early arrival of vibration stimulus to mechanoreceptors on a leg excites the corresponding command O pe n A cc es s D at ab as e w w w .in te ch w eb .o rg

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.

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.

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.

With the rapid development of subway systems, the negative environmental impacts of vibration induced by subways has gradually become a research hotspot. For the purpose of developing predictive models of vibration and designing effective vibration mitigation systems, continuous field dynamic measurements were conducted simultaneously in a subway tunnel, ground, and building in eastern China, the most prosperous region in China. The characteristics of vibration transmission and attenuation induced by subway were analyzed by statistical analysis of large amounts of measurement data. The results showed that most prominent and visible attenuation of vibration is from the track to the ballast bed in the tunnel, where the ground-borne vibration would quickly decrease exponentially with distance. The results also showed that the measured attenuation value of indoor vibration was approximate 0.76 dB on average between each floor. Moreover, the decay ratio of the vibration increased with the increase in the frequency range. Based on these findings, construction gauge of 20&ndash, 25 m outside of the tunnel is recommended. In addition, reducing the vibration source excitation intensity is the most effective vibration isolation method, especially by track structural transformation.

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.

The objectives of this article were to review the literature on endodontic procedures published in various journals during the last two decades. The various obturation techniques, viz. single -cone technique, multiple-cone technique, chemo-plasticized gutta-percha, thermo-plasticized injectable gutta-percha, obturation using pastes, and SPAD/resorcinol formaldehyde, have been described and compared. The various methods used for qualitative and quantitative evaluation of micro-leakage, viz. micro-computed tomography, radiography, CT scans, cone-beam computed tomography, scanning electron microscope, fluid filtration method, dye penetration test, and bacterial leakage technique, have been described and studied by various researchers. The consultation with endodontic experts indicates that substantial improvements can be recommended on obturation procedure, and also, a few modifications may be required in obturation devices from productivity as well as ergonomics point of view. A total of 250 research papers and patents (19 Nos) have been shortlisted for conducting literature survey. The shortlisted paper was classified into various categories, viz. root canal obturation techniques (63 Nos), micro-leakage evaluation techniques (80 Nos), and root canal obturation sealing ability (75 Nos), root canal obturator design (36 Nos), and root canal geometrical parameters (25 Nos). The following statements are deduced from the above literature survey: (1) End outcome of the comparison of the various techniques revealed that warm vertical condensation is the best technique. (2) Consultation with the experts revealed that there is a need of obturator device which combines heat and vibration source. (3) The fluid filtration is the best technique as compared to other experimental techniques. Micro-computed tomography is the best qualitative and nondestructive technique. (4) There is a need for the development of an analytical model which can quantify the root canal obturation.

Preservation of historical buildings is a main challenge in civil engineering field. One of the main concerns in this regard is metro induced vibration received by historical structures. There is a need to evaluate effectiveness of vibration mitigation measures in preservation of monumental buildings. The most widely used method of reducing metro vibrations is changes in the structure of the vibration source (not sufficiently investigated in the literature). In response to this need, effectiveness of track stiffness reduction in mitigation of vibration was investigated in this research. Comprehensive field tests were conducted in the Iranian metro lines. The track stiffness as well as the induced vibrations were measured. It was shown that track stiffness has noticeable role in the track levels of vibration, and in turn in metro vibration reduction. The amounts of vibration reduction were derived as a function of track stiffness reduction.

Summary JSC Bashneftegeofizika, the largest domestic oilfield services company with more than 85 years of history, is a group of high-tech companies that specialize in performing a wide range of geophysical research to develop and operate oil and gas fields. Due to the wide spread of the idea of import substitution, Bashneftegeofizika JSC set itself the task of creating a domestic source of excitation of a seismic vibration signal, which by its characteristics will not be inferior to foreign analogues. Technical capabilities of our company allowed us to develop and launch our own vibrating installations “Batyr”. The tests performed showed the results corresponding to the task in hand.

Band saws machine is the most efficient metal cutting machine. By losing less material, material qualitative, having big saw range and having low cutting costs are superiority of band saws. Band saws are acting with most long route and more limited support point in all cutting tools. In band sawing machine, band saws and structure are easy to produce vibration. Affect cutting life, costs of band saws and material surface topography. So this study focuses on analyzing what is vibration cause of band saws by vibration source and establishes the relationship between band saws natural frequency along and change cutting condition. In this research use the C-430GNC band saws machine, and use S45C material for cutting test. Accelerometers are used with a measurement system to capture sawing vibration data. By the fast Fourier transform to analyze spectrogram transform in order to identified characteristic spectrums, and find out vibration feature with band sawing operating conditions and unusual evens came from wear of blade. Minimum cutting vibration and best surface topography were compared to find out the best cutting condition.

Using UDEC discrete element numerical simulation software and a cosine wave as vibration source, the whole process of rockburst failure and the propagation and attenuation characteristics of shock wave in coal-rock medium were investigated in detail based on the geological and mining conditions of 1111(1) working face at Zhuji coal mine. Simultaneously, by changing the thickness and strength of immediate roof overlying the mining coal seam, the whole process of rockburst failure of roadway and the attenuation properties of shock wave were understood clearly. The presented conclusions can provide some important references to prevent and control rockburst hazards triggered by shock wave interferences in deep coal mines.

The propagation of acoustic emission (AE) signal in waveguide is quite important for AE-based prediction of dynamic disasters in coal rocks. In this study, based on some relevant theories in wave mechanics, the elastic mechanical model of one-dimensional (1D) waveguide was firstly established, and the relationship between AE source signal and the signal at the waveguide’s receiving end was derived. On the basis of theoretical analysis, numerical simulation and laboratory test schemes were designed; additionally, using the standard vibration source method, AE response in different sizes of waveguides were investigated, the effects of waveguide size of waveguide were concluded, and the application conditions of the established theoretical model were clarified. Numerical simulation results fit well with the laboratory test results. Meanwhile, the effects of the sensor’s installation method on the propagation rules of AE signal were examined and appropriate installation method was determined.

A finite element model was developed to simulate the crane induced vibration on the steel structural levels of high-tech factories, in which the mesh includes two-node beam elements to simulate building members and rails, four-node plate elements to simulate building floors, spring-damper and moving wheel elements to simulate the crane. In addition, the rail irregularities, which is the major vibration source for moving cranes, were also included in the finite element analysis. The finite element results were then compared with the experimental measurements to investigate the accuracy of the numerical model, and the comparison result indicates a good agreement. Thus, it is helpful to perform parametric studies using this correct finite element model to understand the behavior of vibration induced by the crane moving on the high-tech factory.

To assess the vibration influence of punching machine to surrounding buildings, a field test is carried out in a certain mold punching company. After analyzing the intensity of vibration source, Z vibration level (VLZ) and other indicators, the vibration comfort of the buildings is evaluated according to the requirement of standards. Their results show that the operation of the punching machine causes the vertical vibrations in second and third floors for a three-story lightweight steel construction which is 75 m far from the punch machine to be out of limits while the ground floor not. And then they make the staff of these floors uncomfortable. It is indicated that the influence of punching machine to the light steel structure building should be taken into consideration the location, and if necessary, countermeasures should be taken to reduce such effects.

In an increasingly urbanized areas transport vibration source are closer and closer to the receiver which is a building. At the same time residents requirements for comfort in rooms are higher. In this paper influence of transport vibrations from various types of trams on human perception was tested and analysed. Measurements were made in Cracow on 11 buildings located near tramway. Human perception were investigated according to ISO and Polish standard. Basic RMS method and additional VDV method were applied because of high crest factor of recorded signal. Results of both methods were compared.

A comfort analysis for the building at a metro depot is presented in this paper with FEA method. First, the dynamic analysis for the whole building structure is performed and the acceleration response of each floor is calculated and compared with the civil codes, based on which the structural comfort is estimated. And then, the major factor resulting in the comfort problem of shear-wall buildings is obtained by frequency domain analysis and it is the summation of mode participating coefficients according to the peak-amplitude frequency-range of vibration source. And finally, an advice for the modification of building design is presented to avoid the structural comfort problem.

Aiming at a 1220 strip surface, where the Cold Rolling Mill had chatter marks, on which the reasons for the formation was tracked tested for in-depth study. Based on the vibration test, the analysis was given to the dynamic characteristics of the rack [1-3]. It was found that had reaction to the mill that caused the forced vibration mill to further accelerate the formation of chatter marks. In the analysis of the mechanism on the chatter marks, the relationship between chatter marks spacing and vibration source was considered in successfully finding out the cause of the 1220 mill chatter marks generated, and then the chatter marks suppression measures were proposed with satisfied effects.

In this paper, a set of spindle vibration test equipment has been designed by using modern design method, on the basis of in-depth study of spindle vibration source .The device includes three parts: machinery, detection and control .In the mechanical part, using sensor fixed machine mobile systems, the design of the spindle drive part and test board was carried on respectively .In the detection part ,the virtual instrument Labview graphical programming language was adopted to form a spindle vibration test and analysis system, realizing the acquisition, processing and analysis of the vibration signal .In the control part, Yan Hua movement control cards are adopted to realize control of motor speed, through Labview programming.

Vibration exciting theory of working engine was analyzed based on dynamic method. Model of engine system and mounts was established and simulated in multiple working conditions by Power Unit module of dynamics software excite. Vibration acceleration of points on engine block adjacent to each mount was extracted to characterize and evaluate the vibration excited by engine in different working condition.

As regards the reliability of the vehicle electronic devices on the tracklayer getting worse due to severe vibration, isolation theory and mechanical model of the GWF vibration isolator and wire-mesh vibration isolator were analyzed, and the test research on the isolation effectiveness of the two isolators applied to the isolation of the vehicle electronic devices were carried out. The test results show that the vibration source of the foundation of the electronic device is mainly from the structure resonance, and the two dry friction vibration isolators exhibit excellent isolation effectiveness on different roads and at different speed. The wire-mesh vibration isolator shows better performance than GWF vibration isolator on three-dimensional comprehensive isolation.

According to the vibration in a residential building, a field investigation was conducted. Using the elimination strategy, the primary vibration source was determined, the vibration serviceability of the residential building was assessed by the environmental vibration tests, and the measures for vibration reduction were proposed. The results show that the vibration in the residential building is caused by 5 textile mills nearby, among which, Mill II has significant effect on the residential building. By applying the measures for vibration reduction to Mill II and reinforcing the residential building, the vibration serviceability can be improved.

The engineering structures which based on laminated composites, have a high probability of unexpected damage development during services. The damage formations must be monitored from the beginning before it headed towards structural failure which could result in substantial damage. This lead to the necessity of Structural Health Monitoring (SHM) system to be installed during the construction of laminated composite structures. However, an understanding of damage area detection and damage characteristics is essential, before a SHM system can be integrated into the structures. This article presents the effects of propagating wave propagation through an existing damage on composite plates. Theoretically, a propagating wave that started from any source will vary when crossing an area with damage. This study shows a high frequency wave propagation (kHz range) show different reactions when passing through the damaged area, compared with the low frequency wave propagation. Results of the study will lead to good damage detection method, which utilizing the available vibration source; especially for the condition monitoring of thin laminated composite structures.

The isolation of vibrations from the surroundings is one of the important problems in the design of machine foundations. The use of open trenches, infilled trenches, single and multiple pile rows have been widely studied. In this paper, the vibration screening efficiency of an inclined secant micro-pile wall positioned as an active vibration barrier is investigated. The study is performed using three-dimensional time domain finite element analyses. Various parameters such as barrier depth, inclination, barrier distance and load excitation frequency were studied. The results show that inclined secant micro-pile walls are a viable vibration isolation option for a multitude of vibration problems. It is shown that varying barrier inclination angle from 90° to 120° improved vibration isolation performance as high as 44% relative to the vertical barrier for the active isolation case. The effectiveness of the barrier increases as its depth increases and also as the excitation frequency increases. The orientation of the inclined barrier towards or against vibration source is shown to be a fundamental design consideration.

This paper presents the estimation of vibration strength obtained from reception structure method. It describes a laboratory-based measurement procedure, which determines the strength of a vibration source in terms of its total squared free velocity. The source used in the experiment is a small electric fan motor. Here instead of using the usual flat rectangular plate, a thin stainless steel beam was used as the reception structure. The aim is to validate the data obtained from the reception method with that from the direct measurement. A good agreement is found between the two results, although small discrepancies occur due to the modal behavior of the beam.

The flow-induced micro-vibration in Shuifu County Town near Xiangjia Dam is studied in this paper. First the characteristics of the micro-vibration are investigated based on the in situ measurement, and then the dynamic property of the still basin which is thought to be the vibration source is analyzed with the effect of fluid-structure interaction (FSI) considered. Finally, the reason of the micro-vibration in Shuifu county town is discussed and several possible engineering suggestions for vibration reduction are also proposed.

Building up the 3D numerical analysis and computing model, force properties of buried pipelines under vibration loads induced by bridge pile foundation construction were researched, to evaluate and control the influence of construction vibration on adjacent buried pipeline. It was concluded that the most adverse position of impact loads effect on pipeline appeared in the upper right and lower left parts of the pipeline closed to the side away from the pile hole about a quarter of an arc. And the peritubular stress distribution curve with the change of the vibration source location were approximately sinusoidal line, parabola and the cosine line changes. Another, under the same conditions, the vibration velocity of ground above the pipeline was significantly greater than the pipeline itself vibration velocity, so through a reasonable assessing and controlling the vibration velocity of ground above the pipeline, it could be made security decisions for buried pipelines. Finally, according to the horizontal spacing of the buried pipeline and shock vibration source, the pipeline grading protection measures were proposed, with achieving better results in engineering application. Research results could provide some evidence both for the force calculation and design construction of the pipeline project, and support for scientific decision-making of the bridge pile foundation construction. It has an important social and economic efficiency.

Zhengyang Men which is located on the north-south axis line of Beijing, is surrounded by the vital communication lines, and suffered from the environmental vibration induced by the busy ground traffic. In order to study the dynamic response of Zhengyang Men city gate and arrow tower, which is caused by ground traffic, the vibration characteristic of ground traffic is the basic research content. The motion equation, which is established by means of the vehicle dynamic model, and the ground traffic characteristic, which is summarized based on the traffic site investigation, are used to derive the vibration source form of a single type vehicle, further more the form of different type vehicle. And then the vibration source can be used for studying the dynamic response of city gate and arrow tower.

A novel vibration source separation and identification method using the denoising source separation (DSS) technique is proposed for the mixed mechanical vibration signals from engines in ships. Denoising source separation enables us to extract the source signals from the mixed signals without prior knowledge of sources and their mixing mode, and thus the important source information extracted by DSS can be used to monitor or actively control engine noises. Different denoising functions such as energy, skew, kurtosis, and tangential functions in DSS are applied to both simulation studies and experimental data to evaluate their separating performances. The tangential function provides the best outperformance with both numerical study and engineering application. In addition, the effectiveness of the proposed DSS method is validated by correlation analysis and the frequency marker tracking method.

This paper provides a illustration of the micro vibration measurement as well as the major vibration source of precision equipment. According to propagation and attenuation law of vibration in the soil, this paper gives some methods of control vibration which used in practical projects. And it inntroduces the anti-micro vibration measures in the design of precision equipment.

The location of a vibration source within a machine is sometimes found to have a significant impact upon the machine's radiated sound power. Radiation mode analysis is known to be a powerful tool for interpreting and predicting sound radiation from a vibrating object since radiation modes are independent of a structure's surface vibration. However, knowledge of the radiation modes alone cannot be used directly to understand the relationship between vibration source location and sound power radiation. Previously, it was suggested that the radiation mode concept could be extended to understand the relationship between the sound power and the driving force distribution by combining a structure's mobility matrix and its radiation modes to form force radiation modes (frad-modes). It was demonstrated by simulation that the radiated sound power can be reduced by choosing the driving force location to be at or near the nodes of the force radiation modes. Here, to further validate the usefulness of the force radiation mode concept, the acoustic transfer vectors and the mobility matrix of a thin steel strip mounted in a rigid baffle were first measured. Then, the force radiation modes were calculated by using the experimental data and it was confirmed that the force radiation modes can serve as a practical guide for choosing a vibration source location that minimizes the radiated sound power, especially at low frequencies.

A new stiffness identification method for a high-rise building is proposed when the building includes an unknown vibration source at the top. By performing limit manipulation, the ratios between shear stiffness coefficients of consecutive stories can be obtained from the floor acceleration data and the ratios of the rotational stiffness to the shear stiffness (SR stiffness ratio). The level of stiffness coefficients can be determined to satisfy the recorded lowest natural frequency and the SR stiffness ratios can be obtained to satisfy the compatibility of higher-order natural frequencies. The validity of the proposed method is examined through actual recorded data.

The existing blind source separation algorithm has two problems for the separation of the vibration signal of the transformer. One is the uncertain number of the transformer vibration source. The other is the vibration measuring point, which is not sure after the signal separation. Aiming at these problems, this paper apply the Wavelet-SVD-Clustering analysis method on determinating the number of sources by using one single sensor acquisition of transformer tank vibration signal. The effectiveness of the method is verified by simulation and experimental data analysis. The method of this paper provides guarantee for the correct analysis and separation of the transformer vibration signal.

Regenerative shock absorber is able to improve the energy conservation, ride comfort and handling of vehicles by suppressing oscillatory motion due to road roughness. This paper presents the performance studies of modelling and testing for a hydraulic regenerative shock absorber system with different sizes of gas-charged accumulator in order to improve the stability of hydraulic behaviour and power regeneration. The model is proposed to stabilize hydraulic flow with variable accumulator capacity with the impressive power regeneration efficiency which is almost constant, and obtained agreeable results between predicted and measured in sinusoidal oscillation. In addition, Random road profiles are also generated as vibration source to investigate the capability of power regeneration experimentally. The results show that the stability and continuity of power regeneration is observably improved by adjusting accumulator capacity.

The environment vibration induced by urban rail transit becomes one of the severe environmental hazards and attracted great attention for researcher at home and abroad. Firstly，on the basis of track irregularity theory, an exciting force function of vibration source induced by ground line train is established. Then, the exciting force acts on the three-dimensional models of rail bearing structure and soil propagation path by utilizing the finite element software. The surrounding environment vibration response caused by train operation is simulated and the numerical results are compared and verified by the field measurement data. Furthermore, the parameter effects of train speed and properties of site soil on environment vibration are studied. The researches show that the numerical simulation in the paper can truly reflect the actual environment vibration caused by urban rail transit with ground line.

*Department of Naval Architecture, Tongmyong University, Busan, KoreaKEY WORDS: Blind source separation 블라인드소스 분리, Plate structure 평판구조물, Vibration source 진동원, Contribution analysis 기여도분석, Independent component analysis 독립성분분석ABSTRACT: The independent component analysis (ICA) technique is a source identification method that uses statistical independence to sep arate source signals from measured signals. It has been successfully applied to various fields such as medical care and communication. In this study, the ICA technique was adopted to analyze the vibration source contr ibution of plate structures. The theory of the ICA technique is introduced and the procedure of the vibration source contribution analysis based o n the ICA technique is proposed. To investigate the applicabili ty of the proposed method to plate structures, numerical examples are presented fo r a rectangular plate under harmonic force excitations. The res ults show that the proposed method could become an effective tool for the vibratio n source contribution analysis of a plate structure.교신저자 김국현: 부산광역시 남구 신선로 428(용당동), 051-629-1658, kimk@tu.ac.kr

Vibration intensity (VI) method is used to reduce sound source generated from air-conditioning rotary compressor. Generally VI method is a good tool to find a sound source through vibration power flow. In this paper, the vibrations are measured by using the 3 uni-axial accelerometer from both the shells of the normal compressor and the fault compressor. The VI method successfully found out the sound source position on the surface of the compressor. In addition, the main noise (3kHz ~ 6.3kHz) was deminished by applying the newly designed compressor inner part which is related to the orginal noise source. Key Words : Vibration Intensity(VI), Rotary compressor, Visualization 1. 서론 우리들의 주거 환경속에서 가정용 공조기(에어컨)는 가정의 필수품으로 여겨지는 가정용 공조기(에어컨)는 가전기기 중의 하나이다. 생활 수준이 높아짐에 따라 일반 가정의 침실 혹은 거실에서 사용되어지는 에어컨에 대한 저진동, 저소음에 대한 사용자의 욕구는 점차 증대되고 있는데, 에어컨의 경우, 다른 가전 제품에 비해 단속 운전에 따른 진동, 소음의 인지도가 커 소비자의 저진동, 저소음화에 대한 욕구가 증대되고 있다. 압축기(rotary compressor)는 에어컨의 주 소음원(noise source)이며 동시에 주 진동원(vibration source)이여서, 전체 에어컨 소음 중 압축기 진동, 소음이 차지하는 비율은 타 부품보다 비교적 크다. 공조용 압축기의 주요 소음원은 로울러, 베인, 컴프레서와 에어컨 프레임과 연결된 배관 진동, 컴프레서 내부의 모터 구동에 의한 모터 구동 소음등 다양한 소음원이 존재한다. 이러한 소음원으로부터 발생한 소음이 컴프레서 내부에서 발생하여 쉘을 통하여 외부로 전달된다. 특히 공조용 컴프레서는 쉘에 직접적으로 내부 구성물들이 용접되어 결합되어 있으므로 내부 소음원별로 발생 위치나 그 전달 경로를 알기 어렵다 [1]. 소음원의 위치를 알아내는 방법으로 일련의 마이크로폰을 사용하는 음향 홀로그래피 방법 [2]과 진동 픽업으로 진동 에너지의 흐름을 측정하는 진동 인텐시티 해석방법이 있다[3]. 진동 인텐시티 기법은 1970년에 Noiseux 에 의해서 처음으로 도입되었는데, “판 또는 보내를 굽힘파에 전파

Purpose: To test patient acceptance and reproducibility of the 3D magnetic resonance elastography (MRE) brain exam using a soft vibration source, and to determine if MRE could noninvasively measure a change in the elastic properties of the brain parenchyma due to Alzheimer's disease (AD). Materials and Methods: MRE exams were performed using an accelerated spin-echo echo planar imaging (EPI) pulse sequence and stiffness was calculated with a 3D direct inversion algorithm. Reproducibility of the technique was assessed in 10 male volunteers, who each underwent four MRE exams separated into two imaging sessions. The effect of AD on brain stiffness was assessed in 28 volunteers, 7 with probable AD, 14 age- and gender-matched PIB-negative (Pittsburgh Compound B, a PET amyloid imaging ligand) cognitively normal controls (CN−), and 7 age- and gender-matched PIB-positive cognitively normal controls (CN+). Results: The median stiffness of the 10 volunteers was 3.07 kPa with a range of 0.40 kPa. The median and maximum coefficients of variation for these volunteers were 1.71% and 3.07%. The median stiffness of the 14 CN− subjects was 2.37 kPa (0.44 kPa range) compared to 2.32 kPa (0.49 kPa range) within the CN+ group and 2.20 kPa (0.33 kPa range) within the AD group. A significant difference was found between the three groups (P = 0.0055, Kruskal–Wallis one-way analysis of variance). Both the CN+ and CN− groups were significantly different from the AD group. Conclusion: 3D MRE of the brain can be performed reproducibly and demonstrates significantly reduced brain tissue stiffness in patients with AD. J. Magn. Reson. Imaging 2011;. © 2011 Wiley-Liss, Inc.

Vibration sources, which caused the vibration of a shear-wall residential building, are inversed in this paper. In light of the test data, frequency-domain analysis is presented, and a finite element model is established. Furthermore, the time-domain acceleration responses of the structure are obtained. In compare with the British standard Vibration Dose Value (VDV) method, an Annoyance-Based Checking Procedure (ABCP) is proposed to evaluate the vibration of the building. The analysis indicates that both results agree reasonably well. A suggestion for structure engineers is proposed to consider the effect of environment vibration in the vicinity of the building.

This paper is a critical review of information pertinent to the behaviour of stadia structures subjected to dynamic crowd loading. It is intended to introduce and explain key concepts in the field as well as summarise the development of current guidance and methods for modelling and assessing crowd occupancy. The review is structured by presenting a field overview and then rationalising the materials found into a standard vibration serviceability problem defined by the vibration source, path and receiver. After briefly introducing the problems associated with dynamic crowd loading, the loads generated by various actions of occupants are discussed. This leads into methods for modelling these activities. The derivation of relevant dynamic structural properties, through both FE modelling and field dynamic testing, is briefly investigated. The concept of human–structure interaction, the merging of dynamic properties of occupants and structure, is considered in depth. Finally, methods for assessing vibration levels are discussed and currently available codes and guidance are appraised in the context of the issues outlined. Further work is required at all stages of the excitation/source (crowd load models which account for flexible structures and large, distributed crowds), system/path (methods for accounting for the effects of occupancy upon system dynamic properties) and response/receiver (occupant tolerance levels) serviceability assessment approach in order to be able to understand and model the outlined phenomena accurately.

The effect on the feeding rate and feeding stability of the multi-point piezoelectric vibratory feeder, of various factors such as driving mode, operating frequency and input signal phase difference is analyzed in detail through many experimental researches by means of the multi-point piezoelectric vibratory feeder developed by ourselves. It is found that the driving mode has critical influence on the conveying performance of the multi-point piezoelectric vibratory feeder. Symmetrical two-point, front single-point and rear single-point vibration sources, these three driving modes have their conveying performance relatively stable. However, three-point, asymmetrical two-point and bottom single-point vibration sources, these three driving modes have their feeding rate somewhat lower than that of the former three modes in the same conditions and their conveying performance is extremely unstable. In particular for the driving mode of single-point vibration source with the bottom close to the rear, conveyance of materials is almost impossible. The effect of phase difference is represented in the driving mode of multi-point vibration sources.

The application of vibration analysis in fault diagnosis of rotary machine becomes more and more popular. Aiming at an abnormal high frequency vibration of a stern bearing, this paper proposed a method of fault diagnosis based on the analysis of vibration characteristics and the spectral analysis. From the gathered vibration data of a stern shaft bench through Pulse Vibration Analysis Platform, using the speed spectrum array to determine the characteristics of vibration source, with the analysis of vibration characteristics of the bench, it concluded that the abnormal high frequency vibration source of the stern bearing is a weak rigidity part of bench─ tacho-torque meter. The vibration data of again test after strengthening the part illustrated the validity of this diagnostic mode.

Accord to the vibration of the floor of one light bus ,the analysis based on experiment is done to confirm that the vibration source is resonance of the subframe. The modal analysis and optimal design is done with Hyper-OptiStruct .The experimental validation of real car is completed and the results show that the optimization is effective and reasonable

This paper presents a novel cost-effective non-destructive evaluation (NDE) method for detecting defects in tiled-walls of high-rise buildings. The method is based on impact acoustic technique which identifies the bonding quality of tiles by analyzing the acoustic vibration signals generated by tapping a structure with an impacting device. However, the basic impact acoustic method, which uses a single impacting device, can only provide a single-point inspection and will take time to inspect a large high-rise building. To speedup the evaluation process, impacting the structure simultaneously with multiple impacting devices are being developed to increase the coverage area of the inspection. However, the sound signals generated by multiple impacting devices are more complicated than those from a single impacting device. Through the analysis of the raw sound data, this paper proposes a regional integrated bispectra method to extract the feature vector and a threshold method for classifying the bonding quality of tiles for multiple impacting devices. The experimental results confirm the validity of the proposed method.