Ground Vibrations

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Ground vibrations and airborne sounds generated by motion of rock in a river bed

Ground vibrations and airborne sounds generated by motion of rock in a river bed

Background noises were first measured to help identify ground vibrations and airborne sounds generated during these experiments. Measurements indicated that the back- ground noise for ground vibrations is rather stable, with a small velocity amplitude of 0.004 cm/s and a frequency of 10 Hz. However, background noise seems to be a greater is- sue for airborne sounds because of wind sensitivity. Wind speed was not measured during the experiments. Figure 2 shows the typical background noise for airborne sounds that were detected in field tests performed on 16 May 2007, which was a windy day. Figure 2a plots time-series data, Fig. 2b plots signals in the frequency domain obtained us- ing the Fast Fourier Transform (FFT) and Fig. 2c plots the Gabor coefficients of the time-domain signal. Signals in the frequency and time-frequency domains suggest that most fre- quencies are below 10 Hz.
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A New Method of Estimating Wave Energy from Ground Vibrations

A New Method of Estimating Wave Energy from Ground Vibrations

Performance of explosive energy is rated in a number of ways, obtained either from theoretical calculations or from experimental tests. However, it is difficult to determine the amount of the ex- plosive energy transferred to the rock and converted into efficient work in the application of rock blasting. Although measurement of some of the effects of explosive energy in rock mass is ground vibration, noise, etc., which are usually conducted for blast control/analysis purpose, the results are rarely used on energy content. Energy transferred to the rock in the form of seismic waves is called seismic energy. In conventional analysis of blast results, generally, the ground vibrations generated due to blasting operations are monitored at a known distance from blast site with a geophone/ground vibration monitor, in three mutually orthogonal directions. Using such wave forms, an energy component is estimated from all the wave forms in three directions, using a so- phisticated signal processing software, which is termed as “wave energy”. The wave energy is compared with the estimated seismic energy. An investigating program was taken up involving 31 blasts conducted at a hard rock excavation site to assess the influence of depth of excavation and scaled distance on the seismic energy wasted in the form of ground vibrations.
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Modelling ground vibrations induced by harmonic loads

Modelling ground vibrations induced by harmonic loads

Examples of BEM approaches include the work of Beskos et al. (1986), who presented a comprehensive review of the work carried out on the dynamics of foundations up to the 1980s. The BEM was employed by von Estroff and Schmid (1984) to model the dynamic behaviour of a strip foundation overlying a soil stratum over bedrock and by Abascal and Dominguez (1984), who used the same technique for simulating the dynamic behaviour of strip foundations over half-space. Spyrakos and Beskos (1986) developed a boundary-element time domain method and examined the dynamic response of surface and embedded foundations under plane strain con- ditions. Israil and Ahmad (1989) presented a parametric study using the BEM for modelling the dynamic behaviour of strip foundations over homogeneous half-space media and then over a soil deposit over either half-space or bedrock. The authors investigated the effect of material properties such as damping and relative stiffness between the soil layers. They also con- sidered the effect of the half-space and the stratum depth. A detailed review of BEM, its formulation and applications can be found, for example, in the review paper by Liu et al. (2011) or in text books such as Boundary Element Methods for Soil – Structure Interaction by Hall and Oliveto (2003). More recently, Romero et al. (2013a) used a three-dimensional (3D) non-linear BEM – FEM to deal with soil – structure interaction problems and Romero et al. (2013b) investigated the dynamic soil – bridge interaction in high-speed rail lines. The BEM was also coupled with the FEM to deal with train-induced ground vibrations – for example, Costa et al. (2012) and Barbosa et al. (2015). The FEM has also been extensively used to simulate soil dynamic problems but, given the semi-infinite extent of soil media, as
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PREDICTION OF GROUND VIBRATIONS IN OPENCAST MINE USING NONLINEAR REGRESSION ANALYSIS

PREDICTION OF GROUND VIBRATIONS IN OPENCAST MINE USING NONLINEAR REGRESSION ANALYSIS

In this method by using the variables considered in case 1, by using PPV and frequency equations, the regression coefficients are calculated and predicted the Peak Particle Velocity (PPV) and frequency of the ground vibrations, and then generated an output file which consists of the predicted PPV and frequency. The same procedure is continued for the cases 2 & 3. To know the group of combination of parameters which will produce lesser ground vibrations the total blast design parameters are classified into three cases.

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Railway-induced ground vibrations – a review of vehicle effects

Railway-induced ground vibrations – a review of vehicle effects

Figure 2 illustrates three train types according to their network. The trains were classified according to their main excitation mechanisms. HSTs generate ground vibra- tions that are mainly dependent on quasi-static track deflection, because high-speed lines are typically characterized by very high quality rolling surfaces. This hypothesis is, however, available when the vehicle speed is lower than the critical track/soil velocity. On the contrary, light transit vehicles, like trams or metros, are characterized by a low speed and a relatively high density of singular rail surface defects, like rail joints, rail crossings or even simple necessities like switching gears. The dynamic track deflection mainly contributes to ground wave generation. Between these two extremes, domestic intercity trains travelling at moderate speeds present excitation mechanisms that are a combination of those experienced on both high speed and urban railway lines. Quasi-static track deflection has a non-negligible influence on ground vibrations, in addition to its already present effects of singular defects.
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Large scale international testing of railway ground vibrations across Europe

Large scale international testing of railway ground vibrations across Europe

advanced analytical [9] and semi-analytical [10] models have recently been proposed, particularly for predicting vibrations from underground lines [11], however there is an increasing trend for the utilisation of numerical techniques. In particular, time domain and frequency domain finite element method (FEM) ([12], [13], [14], [15], [16], [17]) approaches have been widely developed. A shortcoming of the FEM is that it becomes computationally expensive for large domains and requires the use of an absorbing boundary to truncate the modelling space [18]. To reduce run- times, the computational domain has been reduced to 2.5 dimensions by assuming that the track is invariant in the direction of train passage ([19], [20]). Although this considerably reduces
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Dynamic Performance on Multi Storey Structure Due to Ground Borne Vibrations Input from Passing Vehicles

Dynamic Performance on Multi Storey Structure Due to Ground Borne Vibrations Input from Passing Vehicles

Vibrations could be easily felt if there is any source of vibration being induced to the ground such as from the heavy passing vehicle such as busses. Nevertheless, vibration occurred in the building is often being ignored especially in our country as it happens in a very small frequency as this country is not the earthquake-possibility area. Apart from being neglected, the vibration induced to the building still need to be studied in order to ensure that the level of vibration induced is acceptable and safe for the occupants of the building. It is very important to ensure that the vibration level does not exceed the recommended standard in tolerance of the office equipments such as computers, machines and more, the occupants and the structure of the building itself. Therefore, the objectives had been achieved where as the structural response on the UTHM's Registrar office building subjected to the ground vibrations input is acceptable and does not exceed the vibration level based on the vibration criteria standard.
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Acoustic module of the Acquabona (Italy) debris flow monitoring system

Acoustic module of the Acquabona (Italy) debris flow monitoring system

This study quantifies the relationship between flow depth, acoustic amplitude of debris flow induced ground vibra- tions and front velocity in the experimental catchment of Acquabona, Eastern Dolomites, Italy. The analysis of data brought about the results described in the following. Debris flow depth and amplitude of the flow-induced ground vibra- tions show a good positive correlation. Estimation of both mean front velocity and peak discharge can be simply ob- tained monitoring the ground vibrations, through geophones installed close to the flow channel; the total volume of de- bris flow can be so directly estimated from the integral of the ground vibrations using a regression line. The application of acoustic technique to debris flow monitoring seems to be of the outmost relevance in risk reduction policies and in the correct management of the territory. Moreover this estima- tion is possible in other catchments producing debris flows of similar characteristics by means of their acoustic charac- terisation through quick and simple field tests (Standard Pen- etration Tests and seismic refraction surveys).
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Ground vibration induced by collapse of 235m cooling tower

Ground vibration induced by collapse of 235m cooling tower

A complete approach for the prediction of the ground vibration due to the collapse of a cooling tower with a height of 235 meter is presented in this study. The causes to induce the tower to collapse could be various accident loads, e.g. explosion or strong wind. The purpose for the prediction of the ground vibration is for the safety evaluation and the plant planning of a planned nuclear power station in China. Firstly, falling weight tests were executed using dynamic compaction method at a construction site. The data for the ground vibrations were measured. Then a finite element method based “falling weight - soil” model was developed to simulate the ground vibration induced by the falling weight and it was verified by the in-site test results. Meanwhile, the simulated collapse processes of the cooling tower under various accident loads were completed in a parallel project, and the results were briefly referred in this paper. Finally, based on the “falling weight - soil” model, a “cooling tower - soil” model was developed to predict the ground vibrations induced by two types of the collapses of the cooling tower. To reduce the numerical consumption, appropriate modeling strategies were executed in building the “cooling tower – soil” model. It was found that, when collapsing, severe vibration occurred in near field of the cooling tower. However, the vibration attenuated rapidly with the increase of the distance.
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VIBRATION TESTING AND PERFORMANCE ANALYSIS OF IC ENGINE EXHAUST VALVE USING FINITE ELEMENT TECHNIQUE

VIBRATION TESTING AND PERFORMANCE ANALYSIS OF IC ENGINE EXHAUST VALVE USING FINITE ELEMENT TECHNIQUE

Two stroke engine valves operated at high loading condition. Due to this failure chances are more. So it needs regular inspection and maintenance so as to reduce failure chances. Hence the operating cost will gate reduced and the life of component is more. Wear effects will produce various issues related to failure, but due to regular inspection and maintenance we are able to increase the life of component. As the valve material is hardest and having good working properties, there are less chances of damage due to the resonance effect. But we know that exhaust valve operates at high temperature and hence at high working temperature there are chances of losing the properties and may get damaged due to vibration. The vibrations are specified in the form of frequency in this paper. The study illustrates the effects of vibration on exhaust valve at high temperature.
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International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com ( ISSN 2250-2459, ISO 9001:2008 Certified Journal,(Volume 4, Issue 12, December 2014)

International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com ( ISSN 2250-2459, ISO 9001:2008 Certified Journal,(Volume 4, Issue 12, December 2014)

character stretching vibrations in the infrared spectrum. The frequencies could not be precisely determined from the experimental spectra in this range due to their low intensities and overlap of the bands 4) The simulated infrared intensities of C 120 O which are

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Vibrations and Waves

Vibrations and Waves

Destructive interference occurs at any location along the medium when the two interfering waves have a displacement in opposite directions,.. resulting in a decreased amplitude.[r]

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The Relative Transversal Vibrations of Printing-Press Cylinders that are Pressed Against Each Other via an Elastic Blanket

The Relative Transversal Vibrations of Printing-Press Cylinders that are Pressed Against Each Other via an Elastic Blanket

The printing press consists of the following cylinders that rotate during its operation and are pressed against each other via a thin (about 2 mm) elastic, rubberized cloth (called a blanket): two plate cylinders, with printing forms attached to them, and two blanket cylinders, with a paper tape moving between them for the printing. During the investigation, the deflections of the cylinders as well as the elasticity and damping of the blanket and the cylinders’ bearing units were assessed. These vibrations caused changes in the pressure between the cylinders, thus reducing the quality of the prints. After investigating the features of the free and forced relative vibrations of the cylinders, it was decided to reduce the intensity of the vibrations by using cylinders with identical dynamic responses. Data from the experimental investigation that show the impact of the variations of the pressure between the cylinders on the quality of the prints are presented. © 2004 Journal of Mechanical Engineering. All rights reserved.
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CFD modelling of the cross flow through normal triangular tube arrays with one tube undergoing forced vibrations or fluidelastic instability

CFD modelling of the cross flow through normal triangular tube arrays with one tube undergoing forced vibrations or fluidelastic instability

A CFD methodology involving structure motion and dynamic re-meshing has been optimized and applied to simulate the unsteady flow through nor- mal triangular cylinder arrays with one single tube undergoing either forced oscillations or self-excited oscillations due to damping-controlled fluidelastic instability. The procedure is based on 2D URANS computations with a com- mercial CFD code, complemented with user defined functions to incorporate the motion of the vibrating tube. The simulation procedure was applied to several configurations with experimental data available in the literature in order to contrast predictions at different calculation levels. This included static conditions (pressure distribution), forced vibrations (lift delay relative to tube motion) and self-excited vibrations (critical velocity for fluidelastic instability). Besides, the simulation methodology was used to analyze the propagation of perturbations along the cross-flow and, finally, to explore the effect on the critical velocity of the Reynolds number, the pitch-to-diameter ratio and the degrees of freedom of the vibrating cylinder.
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Vibration response on MiNT SRC building due to ground borne vibrations from humans using finite element modeling

Vibration response on MiNT SRC building due to ground borne vibrations from humans using finite element modeling

Abstract. Low amplitude of vibration response on laboratory is important problem to explore due to human activity like footstep or walking. Human activity such as walking will produce low vibration amplitude that can affect the sensitivity of sensitive equipment inside the research or laboratories facilities. Microelectronic and Nanotechnology-Shamsuddin Research Center (MiNT- SRC) building at UTHM is selected to be a location for ground borne vibration measurement due to human activities. The research center is chosen due to sensitivity equipment in the building that prone to vibration effect. Finite element modelling is used to analyse the vibration response distribution to overall building. Vibration data input from field measurement is analysed in ANSYS software based on finite element method, and then further analysis in MATLAB software. A ModalV analysis program in MATLAB is used to produce one third octave velocity spectra and vibration criterion curve for the observed floor. The study shows that the vibration criterion for MiNT-SRC building is classified as VC-E at ground floor and VC-B at the first floor. Thus, based on the result analysis, the sensitive equipment is most suitable to locate at the ground floor of MiNT-SRC building.
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Maladie des vibrations

Maladie des vibrations

phie par sonde Doppler des artères des membres supé- rieurs pourrait aussi éliminer les lésions obstructives des gros vaisseaux. Les tests de la conduction nerveuse, qui évaluent la fonction des grosses fibres nerveuses myéli- nisées près des doigts, contribuent à éliminer la com- pression des nerfs médian et ulnaire. Les tests sensoriels quantitatifs, tels que les seuils de perception du courant, de perception des vibrations et de perception de la tem- pérature, peuvent aussi servir à mesurer la fonction des fibres nerveuses fines dans les doigts. Dans le cadre de l’évaluation des caractéristiques musculosquelettiques, la force de préhension est évaluée à l’aide d’un dynamo- mètre. Le Purdue Pegboard Test est souvent utilisé pour évaluer la dextérité générale et la fonction de la main.
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MONITORING DIAGNOSTIC INDICATORS DURING OPERATION OF A PRINT MACHIN

MONITORING DIAGNOSTIC INDICATORS DURING OPERATION OF A PRINT MACHIN

This article deals with monitoring diagnostic indicators during the operation of a ma- chine used for production of packing materials with a print. It analyses low-frequency vibrations measured in individual spherical roller bearings in eight print positions. The rollers in these positions have a different pressure based on positioning these roll- ers in relation to the central roller. As a result, the article also deals with a correlation of pressure and level of measured low-frequency vibrations. The speed of the print machine (the speed of a line in meters per minute) is a very important variable during its operation, this is why it is important to verify the values of vibrations in various speeds of the line, what can lead to revelation of one or more resonance areas. More- over, it examines vibrations of the central roller drive and measurement of backlash of transmission cogs of this drive. Based on performed analyses recommendations for an operator of the machine have been conceived.
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Vibration Analysis of an Infinite Poroelastic Circular Cylindrical Shell Immersed in Fluid

Vibration Analysis of an Infinite Poroelastic Circular Cylindrical Shell Immersed in Fluid

Gazis [1] discussed the propagation of free harmonic waves along a hollow elastic circular cylinder of infinite extent and presented numerical results. Bjorno and Ram Kumar [2] presented theoretical and experimental results of propagation of axially symmetric waves in submerged elastic rods. Chandra et al. [3] studied the axially sym- metric vibrations of cylindrical shells immersed in an acoustic medium. Employing Biot’s [4] theory, Tajuddin and Sarma [5] studied the torsional vibrations of poroe- lastic cylinders. Wisse et al. [6,7] presented the experi- mental results of guided wave modes in porous cylinders and extended the classical theory of wave propagation in elastic cylinders to poroelastic mandrel modes. Chao et al. [8] studied the shock-induced borehole waves in po- rous formations. Vashishth and Poonam Khurana [9] pre- sented the solutions of elastic wave propagation along a cylindrical borehole in an anisotropic poroelastic solid and derived frequency equations for empty and fluid- filled boreholes. Farhang et al. [10] investigated the wave propagation in transversely isotropic cylinders. Tajuddin and Ahmed Shah [11,12] studied the circum- ferential waves and torsional vibrations of infinite hollow poroelastic cylinders in presence of dissipation. Ahmed Shah [13,14] studies the axially symmetric vibrations of fluidfilled poroelastic circular cylindrical shells and
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Synthesis and Effect of Lattice Strain on the Debye-Waller Factors of Zinc Nanoparticles

Synthesis and Effect of Lattice Strain on the Debye-Waller Factors of Zinc Nanoparticles

The values of the particle size, lattice strain, root mean square amplitude of vibrations, Debye-Waller factor and Debye temperature of Zn powders, ground for different durations, obtained in the present study are given in Table1. Although, values of Deby-Waller factor, amplitude of vibration and Debye temperature in the ‘a’ and ‘c’ directions have been determined separately, the average values of these quantities are given in Table1. As the objective of the present work is to investigate the strain dependence of Debye-Waller factors.
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Smart Helmet

Smart Helmet

By means of this project we will provide information including location about the accident to the nearby hospital , so we have chosen GSM and GPS technology to provide such information through SMS and call to their respective family members . We are using GSM module which has SIM card slot to place the SIM and with help of GPS a message with location will be send via SMS. This is the methodology used in the project, let me once again give a brief description about the working of project, The vibration sensor is placed in the helmet such that it detects vibrations of the helmet which can easily sense the impact and perform its fuction before getting any harm to the circuit . When the rider crashes, the helmet hits the ground and the vibration sensor detects the vibrations that are created when the helmet hits the ground and then the Microcontroller will send a SMS an containing information about the accident as well as of location of accident.
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