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1

Experimental response and vibrational characteristics of a slotted rotor  

NASA Astrophysics Data System (ADS)

This paper proposes to perform experimental tests on the vibrational characteristics of a slotted rotor. Changes in the responses of the n× amplitudes are examined for small and deep slots that can be considered as open cracks. The evolutions of the orbital patterns and the 2× harmonic components near one-half of the first critical speed are investigated in details to propose an efficient indicator of the presence of slots in rotor: a special attention is given to both the comparison of the horizontal and vertical maximum amplitudes of the 2× harmonic components, and changes in the size of the inside loop of orbits when the rotor is passing through one-half of the first critical speed. A huge experimental work considering the influences of the slot depth and the orientation of unbalance relative to the slot direction is investigated in order to examine the possibility of detecting the presence of a transverse slot in rotors.

Sinou, Jean-Jacques

2009-07-01

2

Response characteristics of vibration-sensitive neurons in the midbrain of the grassfrog, Rana temporaria.  

PubMed

European grassfrogs (Rana temporaria) were stimulated with pulsed sinusoidal, vertical vibrations (10-300 Hz) and the responses of 46 single midbrain neurons were recorded in awake, immobilized animals. Most units (40) had simple V-shaped excitatory vibrational tuning curves. The distribution of best frequencies (BF's) was bimodal with peaks at 10 and 100 Hz and the thresholds ranged from 0.02 to 1.28 cm/s2 at the BF. Twenty-three neurons showed phasic-tonic and 11 neurons phasic responses. The dynamic range of seismic intensity for most neurons was 20-30 dB. In contrast to the sharp phase-locking in peripheral vibration-sensitive fibers, no phase-locking to the sinusoidal wave-form was seen in the midbrain neurons. The midbrain cells did not respond at low stimulus intensities (below 0.01-0.02 cm/s2) where a clear synchronization response occurs in saccular fibers. Six midbrain neurons had more complex response characteristics expressed by inhibition of their spontaneous activity by vibration or by bi- and trimodal sensory sensitivities. In conclusion, the vibration sensitive cells in the midbrain of the grassfrog can encode the frequency, intensity, onset and cessation of vibration stimuli. Seismic stimuli probably play a role in communication and detection of predators and the vibration-sensitive midbrain neurons may be involved in the central processing of such behaviorally significant stimuli. PMID:2784502

Christensen-Dalsgaard, J; Jørgensen, M B

1989-01-01

3

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

PubMed

Honeybees detect airborne vibration by means of Johnston's organ (JO), located in the pedicel of each antenna. In this study we identified two types of vibration-sensitive interneurons with arborizations in the primary sensory area of the JO, namely, the dorsal lobe-interneuron 1 (DL-Int-1) and dorsal lobe-interneuron 2 (DL-Int-2) using intracellular recordings combined with intracellular staining. For visualizing overlapping areas between the JO sensory terminals and the branches of these identified interneurons, the three-dimensional images of the individual neurons were registered into the standard atlas of the honeybee brain (Brandt et al. [2005] J Comp Neurol 492:1-19). Both DL-Int-1 and DL-Int-2 overlapped with the central terminal area of receptor neurons of the JO in the DL. For DL-Int-1 an on-off phasic excitation was elicited by vibrational stimuli applied to the JO when the spontaneous spike frequency was low, whereas tonic inhibition was induced when it was high. Moreover, current injection into a DL-Int-1 led to changes of the response pattern from on-off phasic excitation to tonic inhibition, in response to the vibratory stimulation. Although the vibration usually induced on-off phasic excitation in DL-Int-1, vibration applied immediately after odor stimulation induced tonic inhibition in it. DL-Int-2 responded to vibration stimuli applied to the JO by a tonic burst and were most sensitive to 265 Hz vibration, which is coincident with the strongest frequency of airborne vibrations arising during the waggle dance. These results suggest that DL-Int-1 and DL-Int-2 are related to coding of the duration of the vibration as sensed by the JO. PMID:19412925

Ai, Hiroyuki; Rybak, Jürgen; Menzel, Randolf; Itoh, Tsunao

2009-07-10

4

Vibrational characteristics of cracked shafts  

NASA Astrophysics Data System (ADS)

The vibrational characteristics of a cracked Timoshenko shaft are investigated in this paper. Analytical expressions and derived curves relating the crack depth and location on the shaft to changes in the first few natural frequencies of the shaft are presented. These expressions are obtained by modeling the crack as bending and shear compliances of equivalent incremental strain energy by using the J-integral concept from fracture mechanics. It is shown that knowledge of the changes in the first three natural frequencies relative to the uncracked shaft is sufficient to estimate the crack depth and crack location in the shaft. Each additional crack in the shaft requires the knowledge of the changes in two more higher natural frequencies.

Rajab, M. D.; Al-Sabeeh, A.

1991-06-01

5

Vibration Characteristics of Pumped Fluid Systems (VCPFS).  

National Technical Information Service (NTIS)

Vibration characteristics of pumped fluid systems were studied to determine possible disturbances of the microgravity environment on board a microgravity mission spacecraft, and to resolve the conflict of using active thermal control systems. Conventional...

D. Eilers G. Racca M. Molzen W. Klask F. Hopfgarten

1986-01-01

6

Vibrational Characteristics of Cracked Cantilever Plates.  

National Technical Information Service (NTIS)

An analytical solution to the vibrational characteristics of a rectangular cantilever plate with a discontinuous boundary condition (crack) at the root is presented. Mechanical damping which may exist as a result of the contact between the crack's free su...

J. S. Ogg

1977-01-01

7

Optimization of passive vibration isolators mechanical characteristics  

Microsoft Academic Search

The contribution of optimization has been essential to the more recent developments in design of new mechanical structures\\u000a and materials. The objective of this work is to apply the models of material and structural optimization to the design of\\u000a passive vibration isolators. A computational tool to identify the optimal viscoelastic characteristics of a nonlinear one-dimensional\\u000a isolator was developed. The cost

Zuzana Dimitrovová; Hélder C. Rodrigues

2010-01-01

8

On the Definitions of Characteristic Molecular Vibrations and the Distribution of Vibrational Energy.  

National Technical Information Service (NTIS)

The relationship of the definition of a completely characteristic normal vibration to the stationary properties of force and compliance constants is examined. The corresponding properties of various distributions of potential, kinetic, and total vibration...

A. J. P. Alix D. E. Freeman A. Mueller

1974-01-01

9

Vibration and acoustic response of a composite plate with inherent material damping in a thermal environment  

Microsoft Academic Search

This paper presents numerical studies on the vibration and acoustic response characteristics of a fiber-reinforced composite plate in a thermal environment by considering the inherent material damping property of the composite material. Initially the critical buckling temperature is obtained, followed by free and forced vibration analyses considering the pre-stress due to the imposed thermal environment. The vibration response predicted is

P. Jeyaraj; N. Ganesan; Chandramouli Padmanabhan

2009-01-01

10

Vibration characteristics about thermal variation of BFP in power plant  

NASA Astrophysics Data System (ADS)

BFPs(Boiler Feedwater Pump) in power plants are used for pumping high pressure and high temperature water. The pressure pulsation of high pressure pumps is the vibration caused by fluid forces. If the frequency of the exciting source is adjacent to one of the natural frequencies of the pump, it can cause high vibration by resonance. The natural vibration characteristics of pump depend on thermal variation. This paper examines vibration characteristics due to thermal variation experimentally and analytically.

Song, A. H.; Song, J. D.; Kim, H. S.; Jung, G. C.

2012-11-01

11

A new method that indicates the peak stress of random vibration response  

NASA Astrophysics Data System (ADS)

It is an important assessment targets that make a quantitative study of the peak stress of random vibration response during the mechanical properties design process of the space payload. Based on the equivalent of the destructive effect of the random vibration peak response and sine vibration response, the paper established the link between the two, obtained the sine vibration input function that equivalent to the destructive effect of the random vibration peak response. Considering the characteristic of the quantitative research that stress of sine vibration can be, the paper analyzed the stress of the sine vibration by the finite element method and indirectly accessed to the random vibration response peak stress which equivalent to the sine vibration destructive effect. This method worked very well to indicate the peak stress of random vibration response during the ground random vibration tests. The paper provided an effective means of predictive and validation method for the mechanical properties design and test during the ground random vibration test evaluation. The developments costs of the engineering can be significant saving and greatly shorten the development cycle by the method of the peak stress of random vibration response indicated during the ground tests. It is also helpful to improve the safety and reliability of the space load structure in order to avoid the failure or fatigue of the ground random vibration tests.

Yan, Yong; Xie, Peng; Xu, Zhen; Jin, Guang

12

Free Vibration Characteristics of Hybrid SPR Beams  

NASA Astrophysics Data System (ADS)

This paper deals with torsional free vibration analysis of single lap-jointed encastre hybrid SPR beams. The finite element analyses are carried out using the commercially-available ANSYS FEA program. The focus of the analysis is to reveal the influence on the natural frequencies, natural frequency ratios and mode shapes of single lap-jointed encastre hybrid SPR beams caused by variations in the material properties of the adhesives. Numerical examples show that the torsional natural frequencies of single lap jointed encastre hybrid SPR beams increase significantly as the Young's modulus of the adhesive increase, but only slight change with an increase in Poisson's ratio. The mode shapes show that there are different deformations in the jointed section of the odd and even modes. These different deformations may result different dynamic response and different stress distributions.

He, Xiaocong; Dong, Biao; Zhu, Xunzhi

2010-05-01

13

Vibration response and harmonic wave propagation of ultrasonic arc drivers  

NASA Astrophysics Data System (ADS)

A piezoelectric curvilinear arc driver designed for an ultrasonic curvilinear motor is evaluated in this study. A design of piezoelectric curvilinear arc driver is proposed and its governing equations, vibration behaviour and wave propagation are investigated. Then, analysis of forced vibration response or driving characteristics to harmonic excitations in the modal domain is conducted. Finite element modelling and analysis of the arc driver are also discussed. Analytical results of free vibration characteristics are compared favourably with the finite element results. Harmonic analyses of the three finite element models reveal changes of dynamic behaviours of three models and also imply operating frequencies with a significant travelling wave component. Parametric study of mathematical and finite element simulation results suggests that stable travelling waves can be generated to drive a rotor on the proposed curvilinear arc motor system.

Smithmaitrie, Pruittikorn; Dehaven, J. G.; Higuchi, K.; Tzou, H. S.

2007-02-01

14

The static characteristic of a vibration isolating system with a low dynamic stiffness characteristic  

Microsoft Academic Search

The most important characteristic of a vibration isolator are its natural frequency and load supporting capacity. The vibration isolation quality in low excited frequencies (input frequencies) is considerably improved by reducing the natural frequency of system. In this way, however, load supporting capacity of a linear vibration isolating system can not maintain without an increase overall dimensions of the elastic

Thanh Danh Le; Kyoung Kwan Ahn

2010-01-01

15

Natural vibration characteristics of gravity structures  

NASA Astrophysics Data System (ADS)

A forced vibration procedure is presented to estimate fundamental and higher frequencies of vibrations and associated mode shapes of gravity structures. The gravity structures considered are retaining walls and gravity dams. The validity of the proposed procedure is tested on three test problems of varying complexity for which the natural vibration frequencies and mode shapes either have known analytical solutions or have been determined via numerical means/field tests by others. Also included are the results of natural vibration frequencies and associated mode shapes for a spillway control structure located near the abutment end of an embankment dam obtained using the proposed procedure. For all problems considered, fundamental frequency and mode shape results using the proposed procedure are compared with the results obtained using an alternative procedure in which static deflections due to the structure's own weight are used as the starting point for free vibrations by setting the gravity vector to zero. All results compare well. The merits of the proposed procedure are discussed. Published in 2006 by John Wiley & Sons, Ltd.

Chugh, Ashok K.

2007-04-01

16

Temperature characteristics of langanite bulk wave vibrations  

Microsoft Academic Search

Langanite (NGL) is the promising material for FC applications. In present work we measured NGL piezoelectric constants at temperature range -196°C-+120°C. This results and previous data on temperature dependencies (TD) other constants enabled to make the complete theoretical analysis of thickness vibration parameters of NGL single and double rotation cuts in wide temperature range. Thermally compensated xybl\\/?\\/? cuts were theoretically

P. A. Senjushenkov; T. V. Hristoforova; B. V. Mill; V. N. Hristoforov; Yu. V. Pisarevsky

1996-01-01

17

Measurement of Structural Response Characteristics of Full-Scale Buildings: Comparison of Results from Strong-Motion and Ambient Vibration Records.  

National Technical Information Service (NTIS)

The report describes the collection and analysis of ambient vibration data from five buildings in the San Francisco Bay area that experienced strong shaking during the Loma Prieta earthquake of October 17, 1989. The buildings represent a range of construc...

R. D. Marshall L. T. Phan M. Celebi

1992-01-01

18

Characteristics of laterally vibrating resonant microcantilevers in viscous liquid media  

NASA Astrophysics Data System (ADS)

The characteristics of microcantilevers vibrating laterally in viscous liquid media are investigated and compared to those of similar microcantilevers vibrating in the out-of-plane direction. The hydrodynamic loading on the vibrating beam is first determined using a numerical model. A semi-analytical expression for the hydrodynamic forces in terms of the Reynolds number and the aspect ratio (beam thickness over beam width) is obtained by introducing a correction factor to Stokes' solution for a vibrating plate of infinite area to account for the effects of the thickness. The results enable the effects of fluid damping and effective fluid mass on the resonant frequency and the quality factor (Q) to be investigated as a function of both the beam's geometry and liquid medium's properties and compared to experimentally determined values given in the literature. The resonant frequency and Q are found to be higher for laterally vibrating microcantilevers compared to those of similar geometry experiencing transverse (out-of-plane) vibration. Compared to transversely vibrating beams, the resonant frequency of laterally vibrating beams is shown to decrease at a slower rate (with respect to changes in viscosity) in media having higher viscosities than water. The theoretical results are compared to experimental data obtained for cantilevers completely immersed in solutions of varying aqueous percent glycerol. The increases in resonant frequency and Q are expected to yield much lower limits of detection in liquid-phase chemical sensing applications.

Cox, Russell; Josse, Fabien; Heinrich, Stephen M.; Brand, Oliver; Dufour, Isabelle

2012-01-01

19

Vibration and acoustic response of a composite plate with inherent material damping in a thermal environment  

NASA Astrophysics Data System (ADS)

This paper presents numerical studies on the vibration and acoustic response characteristics of a fiber-reinforced composite plate in a thermal environment by considering the inherent material damping property of the composite material. Initially the critical buckling temperature is obtained, followed by free and forced vibration analyses considering the pre-stress due to the imposed thermal environment. The vibration response predicted is then used to compute the sound radiation. The critical buckling temperature and vibration response are obtained using the finite element method based on the Classical Laminate Plate Theory (CLPT) while sound radiation characteristics are obtained using a coupled FEM/BEM technique. It is found that the vibration response of the structure reduces with an increase in uniform temperature rise for both Glass Epoxy and PEEK/IM7 materials, but the overall sound radiation of the plate reduces only marginally due to interaction between reduced stiffness and enhanced damping.

Jeyaraj, P.; Ganesan, N.; Padmanabhan, Chandramouli

2009-02-01

20

Experimental investigations on vibration response of misaligned rotors  

NASA Astrophysics Data System (ADS)

Misalignment is one of the most commonly observed faults in rotating machines. However, there have been relatively limited research efforts in the past to understand its effect on overall dynamics of the rotor system. In the existing literature, there is confusing spectral information on the rotor vibration characteristics of misalignment. The present study is aimed at understanding the dynamics of misaligned rotors and reducing the ambiguity so as to improve the reliability of the misalignment fault diagnosis. Influence of misalignment and its type on the forcing characteristics of flexible coupling is investigated followed by experimental investigation of the vibration response of misaligned coupled rotors supported on rolling element bearings. Steady-state vibration response at integer fraction of the first bending natural frequency is investigated. Effects of types of misalignments, i.e. parallel and angular misalignments, are investigated. The conventional Fourier spectrum (i.e. FFT) has limitations in revealing the directional nature of the vibrations arising out of rotor faults. In addition, it has been observed that several other rotor faults generate higher harmonics in the Fourier spectrum and hence there could be a level of uncertainty in the diagnosis when other faults are also suspect. The present work through use of full spectra has shown possibility of diagnosing misalignment through unique vibration features exhibited in the full spectra (i.e. forward/backward whirl). This provides an important tool to separate faults that generate similar frequency spectra (e.g. crack and misalignment) and lead to a more reliable misalignment diagnosis. Full spectra and orbit plots are efficiently used to reveal the unique nature of misalignment fault not clearly brought out by the previous studies, and new misalignment diagnostics recommendations are proposed.

Patel, Tejas H.; Darpe, Ashish K.

2009-10-01

21

Scale-model characterization of flow-induced vibrational response of FFTF reactor internals  

SciTech Connect

Fast Test Reactor core internal and peripheral components were assessed for flow-induced vibrational characteristics under scaled and simulated prototype flow conditions in the Hydraulic Core Mockup as an integral part of the Fast Test Reactor Vibration Program. The Hydraulic Core Mockup was an 0.285 geometric scale model of the Fast Test Reactor internals designed to simulate prototype vibrational and hydraulic characteristics. Using water to simulate sodium coolant, vibrational characteristics were measured and determined for selected model components over the scaled flow range of 36 to 110%. Additionally, in-situ shaker tests were conducted on selected Hydraulic Core Mockup outlet plenum components to establish modal characteristics. Most components exhibited resonant response at all test flow rates; however, the measured dynamic response was neither abnormal nor anomalously flow-rate dependent, and the predicted prototype components' response were deemed acceptable.

Ryan, J. A.; Mahoney, J. J.

1980-10-01

22

Flow-Induced Vibration Characteristics of BWR/6 Jet Pumps.  

National Technical Information Service (NTIS)

Two General Electric boiling water reactor jet pumps, a BWR/6 and a BWR/6-218, were tested for flow-induced vibration (FIV) characteristics in the Large Steam Water Test Facility at Moss Landing, CA, during February and March 1978. Tests were conducted at...

L. V. LaCroix

1982-01-01

23

Free torsional vibration characteristics of compound planetary gear sets  

Microsoft Academic Search

A family of torsional dynamic models of compound gear sets is developed to predict the free vibration characteristics under different kinematic configurations resulting in different speed ratios. The compound gear sets considered consist of two planes of single- or double-planet gear sets connected by a straight long planet. All of the planets are mounted on a single carrier. The system

Ahmet Kahraman

2001-01-01

24

Vibration of mindlin plates using boundary characteristic orthogonal polynomials  

Microsoft Academic Search

The vibration analysis of shear deformable plates formulated on the basis of first order Mindlin theory is presented. The displacement and rotational functions of the plates are approximated by sets of boundary characteristic orthogonal polynomials. The ease of generation and manipulation of these polynomial functions greatly enhances the computational efficiency of the numerical method. The energy functional of the shear

K. M. Liew; K. C. Hung; M. K. Lim

1995-01-01

25

Vibration Exposure and Biodynamic Responses during Whole-Body Vibration Training  

Microsoft Academic Search

ABERCROMBY, A. F. J., W. E. AMONETTE, C. S. LAYNE, B. K. MCFARLIN, M. R. HINMAN, and W. H. PALOSKI. Vibration Exposure and Biodynamic Responses during Whole-Body Vibration Training. Med. Sci. Sports Exerc., Vol. 39, No. 10, pp. 1794-1800, 2007. Purpose: Excessive, chronic whole-body vibration (WBV) has a number of negative side effects on the human body, including disorders of

ANDREW F. J. ABERCROMBY; WILLIAM E. AMONETTE; CHARLES S. LAYNE; BRIAN K. MCFARLIN; MARTHA R. HINMAN; WILLIAM H. PALOSKI

2007-01-01

26

Characteristics and principle of the new cyclostationary and non-Gaussian omni-axis vibration environment  

Microsoft Academic Search

The omni-axis random vibration environment characteristics of repetitive shock machine, a new vibration equipment for reliability enhancement testing, is roundly studied. Firstly the omni-axis vibration acceleration is sampled by using triple axis accelerator under different intensity of vibration. Secondly the all-sided characteristics of the vibration signal is extracted according to related index by using mathematic and physical descriptions such as

Jiang Pei; Hou Jianjun

2010-01-01

27

Flow-induced vibration characteristics of BWR\\/6 jet pumps  

Microsoft Academic Search

Two General Electric boiling water reactor jet pumps, a BWR\\/6 and a BWR\\/6-218, were tested for flow-induced vibration (FIV) characteristics in the Large Steam Water Test Facility at Moss Landing, CA, during February and March 1978. Tests were conducted at normal reactor operating conditions (532°F, 1046 psia and prototypical flow rates) and a variety of off-design conditions. Both jet pumps

1982-01-01

28

Vibrational characteristics of the niobium dichalcogenide. Bulk samples and nanofilms  

NASA Astrophysics Data System (ADS)

A model of the niobium diselenide crystal lattice has been proposed. This model sufficiently describes the vibrational characteristics of both bulk samples and nanofilms with a thickness beyond one three-layered structural element. Calculation of the local Green functions and mean-squared atom amplitudes have been performed using the Jacobi-matrix method. Phonon density of states features stipulated by acoustic branches and low-frequency low-dispersion optical modes cross-over have been analyzed.

Galetich, I. K.; Gospodarev, I. A.; Grishaev, V. I.; Eremenko, A. V.; Kravchenko, K. V.; Sirenko, V. A.; Feodosyev, S. B.

2009-06-01

29

Hormonal responses to whole-body vibration in men  

Microsoft Academic Search

The aim of this study was to evaluate the acute responses of blood hormone concentrations and neuromuscular performance following\\u000a whole-body vibration (WBV) treatment. Fourteen male subjects [mean (SD) age 25 (4.6)?years] were exposed to vertical sinusoidal\\u000a WBV, 10 times for 60?s, with 60?s rest between the vibration sets (a rest period lasting 6?min was allowed after 5 vibration\\u000a sets). Neuromuscular

Carmelo Bosco; M. Iacovelli; O. Tsarpela; M. Cardinale; M. Bonifazi; J. Tihanyi; M. Viru; A. De Lorenzo; A. Viru

2000-01-01

30

Vibration characteristics of aluminum material and its influences on laser Doppler voice acquisition  

NASA Astrophysics Data System (ADS)

Laser Doppler technology is widely used in precision vibration measurement such as voice acquisition. The fundamental of voice acquisition is to detect the vibration of targets induced by sound wave using a Laser Doppler voice acquisition system, and then demodulate the voice signal from interference signal. Therefore the target's vibration characteristics will be the principal factor influencing the effect of voice acquisition. In this paper, we focus on the plane structure's vibration characteristics caused by voice. There are mainly two parts in this paper, simulation and experimental verify. In simulation, the finite element method is used. The Finite Element Analysis method is widely used in material properties analysis, dynamic analysis, and acoustic analysis. Through finite element analysis method, the plane structure models of thick smooth aluminum are established by ANSYS. Then the frequency responses of different constraints are compared. The Laser Doppler voice acquisition system is applied to test and verify the simulation results. The response characteristics of aluminum board under different excitation frequency are measured. The experimental results and simulation results are compared to verify the correctness and reasonableness of simulation. At the same time, this provides theoretical guidance for Laser Doppler voice acquisition system to choose targets and improve voice acquisition performance.

Zhang, Yu-ze; Li, Li-yan; Tong, You-wan; Zeng, Hua-lin; Zhou, Yan

2013-09-01

31

Vibrational dynamics of DNA: IV. Vibrational spectroscopic characteristics of A-, B-, and Z-form DNA's  

NASA Astrophysics Data System (ADS)

Linear and nonlinear IR spectroscopic studies of nucleic acids can provide crucial information on solution conformations of DNA double helix and its complex with other molecules. Carrying out density functional theory calculations of A-, B-, and Z-form DNA's, the authors obtained vibrational spectroscopic properties as well as coupling constants between different basis modes. The vibrational couplings that determine the extent of exciton delocalization are strongly dependent on DNA conformation mainly because the interlayer distance between two neighboring base pairs changes with respect to the DNA conformation. The Z-DNA has comparatively small interlayer vibrational coupling constants so that its vibrational spectrum depends little on the number of base pairs, whereas the A-DNA shows a notable dependency on the size. Furthermore, it is shown that a few distinctively different line shape changes in both IR and two-dimensional IR spectra as the DNA conformation changes from B to A or from B to Z can be used as marker bands and characteristic features distinguishing different DNA conformations.

Lee, Chewook; Cho, Minhaeng

2007-04-01

32

Firmness evaluation of melon using its vibration characteristic and finite element analysis.  

PubMed

The "Huang gua" melons were measured for their physical properties including firmness and static elastic modulus. The vibrational characteristics of fruits and vegetables are governed by their elastic modulus (firmness), mass, and geometry. Therefore, it is possible to evaluate firmness of fruits and vegetables based on their vibrational characteristics. Analysis of the vibration responses of a fruit is suggested for measuring elastic properties (Firmness) non-destructively. The impulse response method is often used to measure firmness of fruits. The fruit was excited using three types of balls (wooden, steel and rubber) and the vibration is detected by an accelerometer. The Instron device was used to measure the static elastic modulus of the inner, middle and outer portions of melon flesh. Finite element (FE) technique was used to determine the optimum excitation location of the chosen measurement sensor and to analyze the mode shape fruits. Four types of mode shapes (torsional or flexural mode shape, first-type, second-type spherical mode and breathing mode shape) were found. Finite element simulation results agreed well with experimental results. Correlation between the firmness and resonant frequency (r2=0.91) and between the resonant frequency and stiffness factor (r2=0.74) existed. The optimum location and suitable direction for excitation and response measurement on the fruit were suggested. PMID:15909331

Nourain, Jamal; Ying, Yi-bin; Wang, Jian-ping; Rao, Xiu-qin; Yu, Chao-gang

2005-06-01

33

Response of a vortex flowmeter to impulsive vibrations  

Microsoft Academic Search

Experiments were performed to study the response of a vortex flowmeter to structural vibrations due to impulsive forces applied on the pipe. Vortex-shedding signals obtained by a piezoelectric sensor embedded in a vortex shedder were examined. Major findings are described as follows. First, by improving the design of the piezoelectric sensor, the sensor sensitivity to structural vibrations could be reduced.

J. J Miau; C. C Hu; J. H Chou

2000-01-01

34

Investigation on the vibration characteristics of a sandwich beam with smart composites — MRF  

Microsoft Academic Search

This paper establishes the vibration model of the smart composites beam featuring magnetorhe- ological fluid (MRF). The vibration analysis is finished under different magnetic field strength. The results show that the natural frequencies and loss factors of the MRF beam are increased with increasing applied magnetic field strength. The structural vibration responses are reduced significantly. The vibration of sand- wich

Baixiang Hu; Dongbing Wang; Pinqi Xia; Qiyin Shi

35

Vibration characteristics of a rotating flexible arm with ACLD treatment  

NASA Astrophysics Data System (ADS)

In this paper, the vibration behavior and control of a clamped-free rotating flexible cantilever arm with fully covered active constrained layer damping (ACLD) treatment are investigated. The arm is rotating in a horizontal plane in which the gravitational effect and rotary inertia are neglected. The stress-strain relationship for the viscoelastic material (VEM) is described by a complex shear modulus while the shear deformations in the two piezoelectric layers are neglected. Hamilton's principle in conjunction with finite element method (FEM) is used to derive the non-linear coupled differential equations of motion and the associated boundary conditions that describe the rigid hub angle rotation, the arm transverse displacement and the axial deformations of the three-layer composite. This refined model takes into account the effects of centrifugal stiffening due to the rotation of the beam and the potential energies of the VEM due to extension and bending. Active controllers are designed with PD for the piezosensor and actuator. The vibration frequencies and damping factors of the closed-loop beam/ACLD system are obtained after solving the characteristic complex eigenvalue problem numerically. The effects of different rotating speed, thickness ratio and loss factor of the VEM as well as different controller gain on the damped frequency and damping ratio are presented. The results of this study will be useful in the design of adaptive and smart structures for vibration suppression and control in rotating structures such as rotorcraft blades or robotic arms.

Fung, E. H. K.; Yau, D. T. W.

2004-01-01

36

Theoretical modeling and characteristic analysis of moving-train induced ground vibrations  

NASA Astrophysics Data System (ADS)

An integrated train-track-subsoil dynamic interaction model of moving-train induced ground vibration is developed on the basis of vehicle dynamics, track dynamics and the Green's functions of subsoil. The model takes account of the vibrations of vehicle components, the quasi-static axle loads and the dynamic excitations between the wheels and track. The analyzed results from an example show that the ground vibration characteristics have a close relationship with train speed and soil properties; the dynamic responses excited by wheel-track irregularity have big influence on the high frequency components of ground vibration; with the increase of distance to the track, the ground acceleration has the tendency of decrease, and the relevance of acceleration curves and train excitation becomes less obvious; the intersections of moving load speed-lines and subsoil dispersion curves are some resonance frequencies that cause the amplification of ground vibrations; there exists a critical speed for moving train that is close to the minimum velocity of the Rayleigh's wave in the subsoil.

Xia, H.; Cao, Y. M.; de Roeck, G.

2010-03-01

37

Effects of sitting postures on biodynamic response of seated occupants under vertical vibration  

Microsoft Academic Search

The biodynamic response characteristics of 13 male and 14 female seated subjects, exposed to vertical vibration, are characterized under different postural conditions. The measurements are performed for a total of 36 different sitting postural configurations realized through variations in hands position (in lap and on steering wheel), three seat heights (510, 460 and 410mm), and seat design factors involving two

W. Wang; S. Rakheja; P.-É. Boileau

2004-01-01

38

Load Characteristics and Vibration Loci at the Driving Surfaces of Ultrasonic Rotary Motor using a Longitudinal-Torsional Vibration Converter  

NASA Astrophysics Data System (ADS)

Characteristics of ultrasonic rotary motors using a longitudinal-torsional vibration converter, 15 to 50 mm in diameter, are studied. To obtain a large torque, ultrasonic motors using one-dimensional longitudinal-torsional converters with diagonal slits are proposed. The converters have simple and tough structures and are driven using only a longitudinal vibration transducer. The vibration converters are fabricated from metal materials and have diagonal slits cut along the converter circumference, adjacent to a nodal position of longitudinal vibration. The ultrasonic motors consist of a vibration converter having a driving part at its free edge, and a rotor part statically pressed to the driving surface using corned disk springs. The vibration characteristics and vibration loci at the driving surfaces of these converters and motors are measured under loaded and nonloaded conditions and at forward and reverse rotating conditions, using two laser Doppler vibrometers. Vibration locus shapes are changed according to the load conditions and frequencies. Maximum torques of over 0.2 N·m are obtained by the converters, 15 to 20 mm in diameter, and at frequencies of 56 to 65 kHz. The maximum revolution speed obtained is over 550 r.p.m. using a 15-mm-diameter motor of 56 kHz.

Tsujino, Jiromaru; Nakai, Kentaro; Sako, Kazuhide; Ikegami, Noritada; Noda, Kohsuke; Suzuki, Ryo

1998-05-01

39

Experimental Investigations on Effect of Damage on Vibration Characteristics of a Reinforced Concrete Beam  

NASA Astrophysics Data System (ADS)

Need for developing efficient non-destructive damage assessment procedures for civil engineering structures is growing rapidly towards structural health assessment and management of existing structures. Damage assessment of structures by monitoring changes in the dynamic properties or response of the structure has received considerable attention in recent years. In the present study, damage assessment studies have been carried out on a reinforced concrete beam by evaluating the changes in vibration characteristics with the changes in damage levels. Structural damage is introduced by static load applied through a hydraulic jack. After each stage of damage, vibration testing is performed and system parameters were evaluated from the measured acceleration and displacement responses. Reduction in fundamental frequencies in first three modes is observed for different levels of damage. It is found that a consistent decrease in fundamental frequency with increase in damage magnitude is noted. The beam is numerically simulated and found that the vibration characteristics obtained from the measured data are in close agreement with the numerical data.

Srinivas, V.; Jeyasehar, C. Antony; Ramanjaneyulu, K.; Sasmal, Saptarshi

2012-02-01

40

Torsion and free vibration characteristics of turbogenerator end windings  

NASA Astrophysics Data System (ADS)

Stator end windings of large turbogenerators are subjected to static and harmonic forces due to electromagnetic interaction of the electric currents in them. In this paper the free vibration characteristics of these end winding coils are analyzed by using a transfer matrix approach, with account taken of the flexural and torsional rigidities of the composite coil section. An analytical method in which Prandtl's stress function and Roth's double infinite series are used is developed for determining the effective torsional rigidity of the composite rectangular sections with jump non-homogeneity along the principal directions of the section. The necessary equations for the space curve representing the end winding coils are developed. The natural frequencies of a single coil have been experimentally determined by an impact hammer test. The theoretical and experimental values are in good agreement.

Narayanan, S.; Krishna Dutt, R. V. S.; Pramanik, A.; Bhave, S. K.

1992-01-01

41

Vibration and damping characteristics of cylindrical shells with active constrained layer damping treatments  

NASA Astrophysics Data System (ADS)

In this paper, the application of active constrained layer damping (ACLD) treatments is extended to the vibration control of cylindrical shells. The governing equation of motion of cylindrical shells partially treated with ACLD treatments is derived on the basis of the constitutive equations of elastic, piezoelectric and visco-elastic materials and an energy approach. The damping of a visco-elastic layer is modeled by the complex modulus formula. A finite element model is developed to describe and predict the vibration characteristics of cylindrical shells partially treated with ACLD treatments. A closed-loop control system based on proportional and derivative feedback of the sensor voltage generated by the piezo-sensor of the ACLD patches is established. The dynamic behaviors of cylindrical shells with ACLD treatments such as natural frequencies, loss factors and responses in the frequency domain are further investigated. The effects of several key parameters such as control gains, location and coverage of ACLD treatments on vibration suppression of cylindrical shells are also discussed. The numerical results indicate the validity of the finite element model and the control strategy approach. The potential of ACLD treatments in controlling vibration and sound radiation of cylindrical shells used as major critical structures such as cabins of aircraft, hulls of submarines and bodies of rockets and missiles is thus demonstrated.

Zheng, Ling; Zhang, Dongdong; Wang, Yi

2011-02-01

42

Characteristics of dual-frequency combined vibrator antenna arrays  

Microsoft Academic Search

The electrodynamic model of Pomomarev et al. (1982) is used to analyze the dependence of mutual distortions in dual-frequency combined vibrator antenna arrays on the thickness and mutual location of the vibrators. Amplitude patterns are obtained for linear phase and equal-amplitude excitation of the vibrators. It is concluded that the results make possible a more complete representation of the distortions

A. S. Ilinskii; L. I. Ponomarev; I. V. Berezhnaia; A. V. Dolgii

1984-01-01

43

Vertical vibration characteristics of seated human bodies and a biodynamic model with two degrees of freedom  

Microsoft Academic Search

Understanding the vibration characteristics of a seated human body is critical for evaluation and improvement of ride comfort\\u000a of various passenger vehicles. There have been very little publications about the vibration characteristics of a seated Chinese\\u000a human body. By using wide-band white noise excitations and a homemade seat sensor, vertical vibration tests were carried out\\u000a on 28 volunteers. Apparent masses

JiangHua Gao; ZhiChao Hou; Le He; QunSheng Xia

44

Vibration Characteristics of Aluminum Plates Reinforced with Boron-Epoxy Composite Material  

Microsoft Academic Search

Vibration characteristics of aluminum plates reinforced with boron epoxy composite material were investigated experimentally and analyt ically. Variations in the natural frequencies, mode shapes, and damping with filament angle were studied. Vibration characteristics of the re inforced plates were also compared with all-aluminum plates.Results of this study demonstrate the merit of using directional com posite materials in design for controlling

Robert R. Clary; Paul A. Cooper

1973-01-01

45

An optimized semiclassical approximation for vibrational response functions  

NASA Astrophysics Data System (ADS)

The observables of multidimensional infrared spectroscopy may be calculated from nonlinear vibrational response functions. Fully quantum dynamical calculations of vibrational response functions are generally impractical, while completely classical calculations are qualitatively incorrect at long times. These challenges motivate the development of semiclassical approximations to quantum mechanics, which use classical mechanical information to reconstruct quantum effects. The mean-trajectory (MT) approximation is a semiclassical approach to quantum vibrational response functions employing classical trajectories linked by deterministic transitions representing the effects of the radiation-matter interaction. Previous application of the MT approximation to the third-order response function R(3)(t3, t2, t1) demonstrated that the method quantitatively describes the coherence dynamics of the t3 and t1 evolution times, but is qualitatively incorrect for the waiting-time t2 period. Here we develop an optimized version of the MT approximation by elucidating the connection between this semiclassical approach and the double-sided Feynman diagrams (2FD) that represent the quantum response. Establishing the direct connection between 2FD and semiclassical paths motivates a systematic derivation of an optimized MT approximation (OMT). The OMT uses classical mechanical inputs to accurately reproduce quantum dynamics associated with all three propagation times of the third-order vibrational response function.

Gerace, Mallory; Loring, Roger F.

2013-03-01

46

Optimization design of vibration characteristics of ship composite brace with rigid vibration isolation mass  

NASA Astrophysics Data System (ADS)

In considering the theory of structural dynamic optimization design, a design method of the structural style of ship composite brace with rigid vibration isolation mass was studied. Two kinds of structural dynamic optimization formulations minimizing the vibration acceleration of the non-pressure hull on the restraining condition of the gross weight of the ship cabin were established: 1) dynamic optimization of the sectional dimensions of the rigid vibration isolation mass in the composite brace; 2) dynamic optimization of the arranging position of the rigid vibration isolation mass. Through the optimization results, sectional dimensions and the arranging position of the rigid vibration isolation mass with better performance in reducing vibration were gained, and some reference was provided for practical engineering designs as well as enrichment of the design method of a novel ship vibration-isolation brace.

Wang, Qiangyong; Yao, Xiongliang; Yu, Danzhu; Pang, Fuzhen

2011-06-01

47

Vibrational coupled cluster response theory: A general implementation  

NASA Astrophysics Data System (ADS)

The calculation of vibrational contributions to molecular properties using vibrational coupled cluster (VCC) response theory is discussed. General expressions are given for expectation values, linear response functions, and transition moments. It is shown how these expressions can be evaluated for arbitrary levels of excitation in the wave function parameterization as well as for arbitrary coupling levels in the potential and property surfaces. The convergence of the method is assessed by benchmark calculations on formaldehyde. Furthermore, excitation energies and infrared intensities are calculated for the fundamental vibrations of furan using VCC limited to up to two-mode and up to three-mode excitations, VCC[2] and VCC[3], as well as VCC with full two-mode and approximate three-mode couplings, VCC[2pt3].

Seidler, Peter; Sparta, Manuel; Christiansen, Ove

2011-02-01

48

On human response to prolonged repeated whole-body vibration  

Microsoft Academic Search

The experiment was aimed at investigating human response to different doses of whole-body vibration (WBV), at checking adaptation to repeated exposures, at further evaluating the frequency weighting, and at examining the effect of a distinct interruption of prolonged exposure. Eight male seated subjects were exposed for 3 h to sinusoidal WBV in the z-axis with the frequencies 4 Hz and

H. SEIDEL; R. BASTEK; D. BRÄUER; Ch. BUCHHOLZ; A. MEISTER; A.-M. METZ; R. ROTHE

1980-01-01

49

Structural damage detection using cross correlation functions of vibration response  

Microsoft Academic Search

Structural damage detection methods based on vibration responses are appealing for a variety of reasons such as their potential to observe damage from sensors placed remote from an unknown damage site. Of particular interest to the authors is online damage detection in which changes in the structure can be flagged up in an automated fashion by permanently installed transducers. In

Le Wang; Zhichun Yang; T. P. Waters

2010-01-01

50

Vibration characteristics of an APS lab facility in Building 401  

SciTech Connect

The vibratory behavior of a lab facility located in Building 401 of the Advanced Photon Source site at Argonne National Laboratory is summarized. Measurements of ambient vibration indicate that acceptable displacement levels are usually maintained (rms value below 0.1 microns) for the measured frequency range, above 0.2 Hz. An exception occurs when strong wind conditions excite a horizontal building resonance near 1.85 Hz to rms levels as high as 0.3 microns. Measurements of the laboratory floor`s dynamic response to directly applied force excitation agree with theoretical predictions. The primary component of the floor construction is a reinforced concrete slab. The slab has a transverse fundamental resonant frequency of 18.5 Hz and an associated damping level of roughly 8.5% of critical. It is also shown via experimental measurements that the linoleum surface adhered to the concrete slab is far more compliant than the slab itself and can significantly influence the floor`s dynamic response to local excitations.

Royston, T.J.

1998-01-01

51

Evaluation of Human Response to Structural Vibration Induced by Sonic Boom.  

National Technical Information Service (NTIS)

This paper addresses the topic of building vibration response to sonic boom and the evaluation of the associated human response to this vibration. The paper reexamines some of the issues addressed in the previous extensive coverage of the topic, primarily...

L. C. Sutherland J. Czech

1992-01-01

52

Linear response of vibrated granular systems to sudden changes in the vibration intensity  

NASA Astrophysics Data System (ADS)

The short-term memory effects recently observed in vibration-induced compaction of granular materials are studied. It is shown that they can be explained by means of quite plausible hypothesis about the mesoscopic description of the evolution of the system. The existence of a critical time separating regimes of ``anomalous'' and ``normal'' responses is predicted. A simple model fitting into the general framework is analyzed in the detail. The relationship between this paper and previous studies is discussed.

Brey, J. Javier; Prados, A.

2001-06-01

53

Semiclassical nonlinear response functions for coupled anharmonic vibrations.  

PubMed

Observables in linear and nonlinear infrared spectroscopy may be computed from vibrational response functions describing nuclear dynamics on a single electronic surface. We demonstrate that the Herman-Kluk (HK) semiclassical approximation to the quantum propagator yields an accurate representation of quantum coherence effects in linear and nonlinear response functions for coupled anharmonic oscillators. A considerable numerical price is paid for this accuracy; the calculation requires a multidimensional integral over a highly oscillatory integrand that also grows without bound as a function of evolution times. The interference among classical trajectories in the HK approximation produces quantization of good action variables. By treating this interference analytically, we develop a mean-trajectory (MT) approximation that requires only the propagation of classical trajectories linked by transitions in action. The MT approximation accurately reproduces coherence effects in response functions of coupled anharmonic oscillators in a regime in which the observables are strongly influenced by these interactions among vibrations. PMID:19947691

Gruenbaum, Scott M; Loring, Roger F

2009-11-28

54

Transmission characteristics of suspension seats in multi-axis vibration environments  

Microsoft Academic Search

The multi-axis vibration transmission characteristics of selected suspension seats were investigated in the laboratory. Subjects were exposed to a flat acceleration spectrum and two low frequency signals extracted from multi-axis acceleration data recorded at the floor of a passenger locomotive. Triaxial accelerations were measured at the floor of the vibration table and at the interfaces between the subject and mounted

Suzanne D. Smith; Jeanne A. Smith; David R. Bowden

2008-01-01

55

Experimental analysis of vibration characteristics of an edge- cracked composite plate by ESPI method  

Microsoft Academic Search

In this paper, the amplitude fluctuation (AF) electronic speckle pattern interferometry (ESPI) method was adopted to investigate\\u000a the vibration characteristics of a composite plate containing an edge crack. The change of the modal shapes was discussed.\\u000a In addition, the stress intensity factors (SIFs) induced by the resonant vibration were evaluated.

Wei-Chung Wang; Chi-Hung Hwang

1998-01-01

56

Research on the low-frequency vibration characteristics of the adaptive isolator based on MR damper  

Microsoft Academic Search

Based on the idea that combining traditional vibration-reduction components parallel with intelligent components, a new approach to the design of isolator which acts as vibration isolator and impact buffer is presented in this paper. With the application of magnetorheological damper (MR damper) and wire rope spring, an adaptive isolator is designed, whose dynamic characteristics is adaptive and controllable. By using

Dongyan Shi; Xianjie Shi

2010-01-01

57

Vibrations  

NASA Astrophysics Data System (ADS)

Low frequent vibrations may cause from disturbing up to damaging effects. There is no precise distinction between structure-borne sound and vibrations. However - depending on the frequency range - measurements and predictions require different techniques. In a wide frequency range, the generation, transmission and propagation of vibrations can be investigated similar to structure-borne sound (see Chap. 9).

Guggenberger, Johannes; Müller, Gerhard

58

Radial Vibration Characteristics of Spherical Nanoparticles Immersed in Fluid Medium  

NASA Astrophysics Data System (ADS)

The vibrational properties of nanoparticles coupled with surrounding media are of recent interest. These nanostructures can be modeled as nanoscale spherical solids. In this paper, new formulation based on the nonlocal elasticity theory is proposed to investigate radial vibrations of the nanoparticles immersed in fluid medium. The nanoparticles with size ranging from 1 nm to 10 nm are discussed. The nanoparticles are considered elastic, homogeneous and anisotropic. Along the contact surface between the nanoparticle and the fluid, the compatibility requirement is applied and the Bessel functions are used to obtain the complex frequency equation. Numerical results are evaluated, and their comparisons are performed to confirm the validity and accuracy of the proposed method. Furthermore, the model is used to elucidate the effect of small scale on the vibration of several nanoparticles. Our results show that the small scale is essential for the radial vibration of nanoparticles when the nanoparticle radius is smaller than 2 nm.

Fazelzadeh, S. Ahmad; Ghavanloo, Esmaeal

2013-10-01

59

Optimization design of vibration characteristics of ship composite brace with rigid vibration isolation mass  

Microsoft Academic Search

In considering the theory of structural dynamic optimization design, a design method of the structural style of ship composite\\u000a brace with rigid vibration isolation mass was studied. Two kinds of structural dynamic optimization formulations minimizing\\u000a the vibration acceleration of the non-pressure hull on the restraining condition of the gross weight of the ship cabin were\\u000a established: 1) dynamic optimization of

Qiangyong Wang; Xiongliang Yao; Danzhu Yu; Fuzhen Pang

2011-01-01

60

Non-linear dual-axis biodynamic response to vertical whole-body vibration  

NASA Astrophysics Data System (ADS)

Seated human subjects have been exposed to vertical whole-body vibration so as to investigate the non-linearity in their biodynamic responses and quantify the response in directions other than the direction of excitation. Twelve males were exposed to random vertical vibration in the frequency range 0.25-25Hz at four vibration magnitudes (0.125, 0.25, 0.625, and 1.25ms-2r.m.s.). The subjects sat in four sitting postures having varying foot heights so as to produce differing thigh contact with the seat (feet hanging, feet supported with maximum thigh contact, feet supported with average thigh contact, and feet supported with minimum thigh contact). Forces were measured in the vertical, fore-and-aft, and lateral directions on the seat and in the vertical direction at the footrest. The characteristic non-linear response of the human body with reducing resonance frequency at increasing vibration magnitudes was seen in all postures, but to a lesser extent with minimum thigh contact. Appreciable forces in the fore-and-aft direction also showed non-linearity, while forces in the lateral direction were low and showed no consistent trend. Forces at the feet were non-linear with a multi-resonant behaviour and were affected by the position of the legs. The decreased non-linearity with the minimum thigh contact posture suggests the tissues of the buttocks affect the non-linearity of the body more than the tissues of the thighs. The forces in the fore-and-aft direction are consistent with the body moving in two directions when exposed to vertical vibration. The non-linear behaviour of the body, and the considerable forces in the fore-aft direction should be taken into account when optimizing vibration isolation devices.

Nawayseh, N.; Griffin, M. J.

2003-11-01

61

Dose-response relationships for hand-transmitted vibration.  

PubMed

Few dose-response relationships have been reported for signs and symptoms resulting from occupational exposure of the hand to vibration. For population groups whose members operate the same vibrating power tool or industrial process throughout the workday, a simple model may be constructed to provide functional dose-response relationships for the onset of episodes of finger blanching. In such groups, the latency interval for various population percentiles may be expressed in terms of a frequency-weighted, root-mean-square, component acceleration at a surface in contact with the hand. Of the two constitutive equations required by the model, one appears to be supported by epidemiologic data published since its derivation, but the second may require modification to be applicable to very short daily exposure durations. PMID:3775313

Brammer, A J

1986-08-01

62

Vibration analysis of shell-and-tube heat exchangers: an overview-Part 2: vibration response, fretting-wear, guidelines  

NASA Astrophysics Data System (ADS)

Design guidelines were developed to prevent tube failures due to excessive flow-induced vibration in shell-and-tube heat exchangers. An overview of vibration analysis procedures and recommended design guidelines is presented in this paper. This paper pertains to liquid, gas and two-phase heat exchangers such as nuclear steam generators, reboilers, coolers, service water heat exchangers, condensers, and moisture-separator-reheaters. Part 2 of this paper covers forced vibration excitation mechanisms, vibration response prediction, resulting damage assessment, and acceptance criteria.

Pettigrew, M. J.; Taylor, C. E.

2003-11-01

63

Transmission Characteristics of Suspension Seats in Multi-Axis Vibration Environments.  

National Technical Information Service (NTIS)

The multi-axis vibration transmission characteristics of selected suspension seats were investigated in the laboratory. Subjects were exposed to a flat acceleration spectrum and two low frequency signals extracted from multi- axis acceleration data record...

D. R. Bowden J. A. Smith S. D. Smith

2008-01-01

64

Seated Occupant Apparent Mass Characteristics Under Automotive Postures and Vertical Vibration  

NASA Astrophysics Data System (ADS)

The biodynamic apparent mass response characteristics of 24 human subjects (12 males and 12 females) seated under representative automotive postures with hands-in-lap (passengers) and hands-on-steering wheel (drivers) are reported. The measurements were carried out under white noise vertical excitations of 0.25, 0.5 and 1.0m/s2r.m.s. acceleration magnitudes in the 0.5-40Hz frequency range and a track measured input (1.07m/s2). The measured data have been analyzed to study the effects of hands position, body mass, magnitude and type of vibration excitation, and feet position, on the biodynamic response expressed in terms of apparent mass. A comparison of the measured response of subjects assuming typical automotive postures involving inclined cushion, inclined backrest and full use of backrest support with data determined under different postural conditions and excitation levels revealed considerable differences. The biodynamic response of automobile occupants seated with hands in lap, peaks in the 6.5-8.6Hz frequency range, which is considerably higher than the reported range of fundamental frequencies (4.5-5Hz) in most other studies involving different experimental conditions. The peak magnitude tends to decrease considerably for the driving posture with hands-on-steering wheel, while a second peak in the 8-12 Hz range becomes more apparent for this posture. The results suggest that biodynamic response of occupants seated in automotive seats and subject to vertical vibration need to be characterized, as a minimum, by two distinct functions for passenger and driving postures. A higher body mass, in general, yields higher peak magnitude response and lower corresponding frequency for both postures. The strong dependence of the response on the body mass is further demonstrated by grouping the measured data into four different mass ranges: less than 60 kg, between 60.5 and 70 kg, between 70.5 and 80 kg, and above 80 kg. From the results, it is concluded that hands position and body mass have the most significant influence on the apparent mass response under automotive posture and vibration. . All rights reserved.

Rakheja, S.; Haru, I.; Boileau, P.-É.

2002-05-01

65

Linear response of vibrated granular systems to sudden changes in the vibration intensity  

SciTech Connect

The short-term memory effects recently observed in vibration-induced compaction of granular materials are studied. It is shown that they can be explained by means of quite plausible hypothesis about the mesoscopic description of the evolution of the system. The existence of a critical time separating regimes of {open_quotes}anomalous{close_quotes} and {open_quotes}normal{close_quotes} responses is predicted. A simple model fitting into the general framework is analyzed in the detail. The relationship between this paper and previous studies is discussed.

Brey, J. Javier; Prados, A.

2001-06-01

66

Vibration and acoustic response of an orthotropic composite laminated plate in a hygroscopic environment.  

PubMed

This paper is a study of the vibration and acoustic response characteristics of orthotropic laminated composite plate with simple supported boundary conditions excited by a harmonic concentrated force in a hygroscopic environment. First the natural vibration of the plate with the in-plane forces induced by hygroscopic stress is obtained analytically. Secondly, the sound pressure distribution of the plate at the far field is obtained using the Rayleigh integral. Furthermore, the sound radiation efficiency is deduced. Third, different ratios of elastic modulus in material principal directions are set to research the effects of increasing stiffness of the orthotropic plate on the vibration and acoustic radiation characteristics. Finally, to verify the theoretical solution, numerical simulations are also carried out with commercial finite software. It is found that the natural frequencies decrease with the increase of the moisture content and the first two order modes interconvert at high moisture content. The dynamic response and sound pressure level float to lower frequencies with elevated moisture content. Acoustic radiation efficiency generally floats to the low frequencies and decreases with an increase of moisture content. The dynamic and acoustic responses reduce and the coincidence frequency decreases with the enhanced stiffness. PMID:23464015

Zhao, Xin; Geng, Qian; Li, Yueming

2013-03-01

67

Studies on vibration characteristics of a pear using finite element method.  

PubMed

The variation of the vibration characteristics of a Huanghua pear was investigated using finite element simulations. A new image processing technique was used to obtain the unsymmetrical and un-spherical geometrical model of a pear. The vibration characteristics of this type of pear with the correlation of its behavior with geometrical configurations and material characteristics were investigated using numerical modal analysis. The results showed that the eigenfrequency increased with the increasing pear Young's modulus, while decreased with increasing pear density, and decreased with increasing pear volume. The results of this study provided foundation for further investigations of the physical characteristics of fruits and vegetables by using finite element simulations. PMID:16691644

Song, Hui-zhi; Wang, Jun; Li, Yong-hui

2006-06-01

68

Causes and Characteristics of the Electromagnetic Vibration of a Capacitor Motor under Load Condition  

NASA Astrophysics Data System (ADS)

The capacitor motors (CRMs) are widely used to drive industrial equipment and electric home appliances. Recently, the reduction of the vibration and noise of CRMs has become increasingly important from the standpoint of environmental improvement. However, electromagnetic vibration of CRMs under load has not been analyzed sufficiently. The present paper theoretically and experimentally discusses the causes and characteristics of CRM electromagnetic vibration under load. The primary conclusions are as follows: (1) The general formula for dominant electromagnetic vibration caused by electromagnetic force wave was derived, including the influences not only of a backward magnetic field but also of magnetic saturation. (2) The dominant electromagnetic vibration of CRMs was theoretically attributed to three types of electromagnetic force waves. Two types of electromagnetic force wave are generated by the interaction of two forward magnetic fluxes, such as those of a three-phase squirrel-cage induction motor, and the other type of electromagnetic force wave is generated under the influence of a backward magnetic flux. (3) The characteristics of dominant electromagnetic vibration depending on load and running capacitor were classified theoretically and experimentally into three types based on the characteristics of the electromagnetic force wave and equivalent circuit current. (4) The influences of magnetic saturation in dominant electromagnetic vibration were verified experimentally and their causes were clarified theoretically in relation to electromagnetic force waves.

Hirotsuka, Isao; Tsuboi, Kazuo

69

Vibration characteristics of vaulted masonry monuments undergoing differential support settlement  

Microsoft Academic Search

This paper assesses the feasibility of vibration testing to detect structural damage caused by the settlement of buttresses in the Beverley Minster, a Gothic church located in the UK. Over the past eight centuries, the accumulated support settlements of the buttresses of Beverley Minster have pulled the main nave walls outward, causing severe separation along the edges of the masonry

Sezer Atamturktur; Luke Bornn; François Hemez

2011-01-01

70

Electrodynamic vibrators  

Microsoft Academic Search

The present work describes current electrodynamic vibrators and vibration rigs for investigating materials, structural elements, machine parts, and certain biological objects subjected to vibrations and large accelerations. Methods of increasing the thrusting force and amplitude of oscillations in electrodynamic vibrators are discussed along with broadening of the frequency range. The characteristics of commercial vibrators are examined. Ways of preventing vibrations

M. D. Genkin; A. M. Rusakov; V. V. Iablonskii

1975-01-01

71

Vibration characteristics in a smart bridge model using shape-memory alloy fiber reinforced composite  

NASA Astrophysics Data System (ADS)

A smart bridge model was proposed for active control on strength and vibration by changing material properties of shape memory alloy embedded in the bridge structure using TiNi/acrylic composite. A systemic experimental study was carried out to investigate the self-strengthening effect by shape recovery of pre-strained TiNi wires as well as vibration control by stiffness changing with direct electric heating method. The deflection and vibration responses are measured by electric strain gages affixed on the bridge floor on which the model train goes through. From these results, we know the smart bridge model of composite material beam has not only been able to reduce the vibration response, but also change the frequency of the structure. The damping and vibration control for the bridge model is confirmed by the measurement.

Shimamoto, A.; Zhao, H.; Abe, H.

2005-05-01

72

Effect of response type and excitation frequency range on the structural damage detection method using correlation functions of vibration responses  

NASA Astrophysics Data System (ADS)

In previous paper by the authors, the inner product vector (IPV) was proposed as a damage detection algorithm which uses cross correlation functions between vibration responses under band pass white noise excitation. As the characteristics of IPVs calculated by different vibration responses (i.e. displacement, velocity and acceleration) under band pass white noise excitation with different frequency range should be different, the effectiveness of the damage detection method may be affected by the response type and excitation frequency range. This paper just investigates the effect of response type and excitation frequency range on the IPV-based structural damage detection method. Firstly, the theoretical formulae of IPVs and the damage index using IPV are reviewed shortly. Then, the effect of response type on the IPVs is analyzed based on the characteristics of the theoretical formulae of IPVs, and the principle for choosing the response type for calculating IPV under band pass white noise excitation with different frequency range is proposed as well. Finally, simulative damage detection examples of a shear frame structure are presented to illustrate the theory and method proposed in this paper.

Wang, Le; Yang, Zhichun

2013-02-01

73

Non-linear torsional vibration characteristics of an internal combustion engine crankshaft assembly  

NASA Astrophysics Data System (ADS)

Crankshaft assembly failure is one of the main factors that affects the reliability and service life of engines. The linear lumped mass method, which has been universally applied to the dynamic modeling of engine crankshaft assembly, reveals obvious simulation errors. The nonlinear dynamic characteristics of a crankshaft assembly are instructionally significant to the improvement of modeling correctness. In this paper, a general expression for the non-constant inertia of a crankshaft assembly is derived based on the instantaneous kinetic energy equivalence method. The nonlinear dynamic equations of a multi-cylinder crankshaft assembly are established using the Lagrange rule considering nonlinear factors such as the non-constant inertia of reciprocating components and the structural damping of shaft segments. The natural frequency and mode shapes of a crankshaft assembly are investigated employing the eigenvector method. The forced vibration response of a diesel engine crankshaft assembly taking into account the non-constant inertia is studied using the numerical integral method. The simulation results are compared with a lumped mass model and a detailed model using the system matrix method. Results of non-linear torsional vibration analysis indicate that the additional excitation torque created by non-constant inertia activates the 2nd order rolling vibration, and the additional damping torque resulting from the non-constant inertia is the main nonlinear factor. The increased torsional angular displacement evoked by the high order excitation torque relates to the non-constant inertia. This research project is aimed at improving nonlinear dynamics theory, and the confirmed nonlinear parameters can be used for the structure design of a crankshaft assembly.

Huang, Ying; Yang, Shouping; Zhang, Fujun; Zhao, Changlu; Ling, Qiang; Wang, Haiyan

2012-07-01

74

Analysis of Thin-Shell Piezoelectric Ceramics with Engineered Resonance Characteristics and Vibration Modes  

Microsoft Academic Search

Piezoelectric ceramic transducers with hollow thin shell forms (cylinder, tube, and cone) were fabricated by slip casting method. Characteristic vibration modes of the thin-shell structures were identified using finite element analysis method. Various vibration modes, such as length extension, radial expansion were obtained from the thin-shell transducers at 50-200 kHz frequencies. The resonance frequencies of these modes were engineered by

Sedat Alkoy

2006-01-01

75

Analysis of radiator characteristics of an antenna array of H-form vibrators  

Microsoft Academic Search

The theory of wire radiators of intersecting wires is presented in [2, 3] and the possibility of a rigorous approach to the analysis of current distribution and input characteristics of similar radiators is demonstrated. The authors of [4] applied this theory to the analysis of the characteristics of a periodic array of vibrators with posts, which permitted determination of the

L. V. Gordienko; L. I. Ponomarev

1989-01-01

76

Variational response-function formulation of vibrational circular dichroism.  

PubMed

The atomic axial tensor (AAT) of vibrational circular dichroism is expressed as the frequency derivative at zero frequency of a linear response function for operators referencing a nuclear displacement and a magnetic field. This is used in the density matrix-based quasienergy derivative Lagrangian approach of Thorvaldsen et al. [J. Chem. Phys., 2008, 129, 214108] to express the AAT in a form where the need to solve response equations for the nuclear displacements is removed, significantly reducing the computation cost compared to existing formulations. The density matrix-based quasienergy derivative Lagrangian approach also allows us straightforwardly to use London atomic orbitals to remove the gauge-origin dependence and to account for the atomic orbitals' dependence on the nuclear coordinates. The formalism is entirely based on atomic-orbital density and integral matrices and therefore amenable to linear scaling for sufficiently sparse matrices and given a linearly scaling response solver. PMID:21283895

Coriani, Sonia; Thorvaldsen, Andreas J; Kristensen, Kasper; Jørgensen, Poul

2011-01-31

77

Vibration and Noise Characteristics of Elliptical Gears due to Non-Uniform Rotation  

NASA Astrophysics Data System (ADS)

Elliptical gear is a typical non-circular gear, which transmits a variable-ratio rotation and power simultaneously. Due to the non-uniform rotation, the vibration and noise of elliptical gears demonstrate particular characteristics which should be paid attention to in practical application. In this paper, two elliptical gears, which are a single elliptical gear and a double elliptical gear, have been investigated to analyze the vibration and noise characteristics of elliptical gears. The corresponding circular gears for comparison are also investigated. General factors including the torque, the rotation speed, the gear vibration acceleration and the gear noise of the four test gears are measured by running test. The root mean square of the Circumferential Vibration Acceleration (CVA) and the sound pressure level of the noise of elliptical gears are obtained from the measured results and compared with those of circular gears to clarify the vibration and noise characteristics of elliptical gears. Furthermore, the frequency analysis of the CVA of elliptical gears is conducted by Fast Fourier Transform Algorithm (FFT) and compared with that of circular gears. The main vibration component of elliptical gear is uncovered according to the obtained frequency spectra. In addition, the Critical Rotation Speeds of Tooth Separation (CRSTS) of elliptical gear is obtained and its relation with load torque is unveiled.

Liu, Xing; Nagamura, Kazuteru; Ikejo, Kiyotaka

78

Effect of dynamic response and displacement\\/stress amplitude on ultrasonic vibration cutting  

Microsoft Academic Search

In this report, the behavior of the cutting force measured through the dynamic response of tool–work piece system in ultrasonic vibration cutting was discussed first. Measured cutting force mainly depends on the ratio of net cutting time to a vibration cycle in vibration cutting (tc\\/T) because the tool–work piece system has much lower natural frequency comparing with the ultrasonic vibration

Kei Harada; Hiroyuki Sasahara

2009-01-01

79

An analytical and experimental study of the vibration response of a clamped ribbed plate  

NASA Astrophysics Data System (ADS)

An analytical solution is presented in this paper for the vibration response of a ribbed plate clamped on all its boundary edges by employing a traveling wave solution. A clamped ribbed plate test rig is also assembled in this study for the experimental investigation of the ribbed plate response and to provide verification results to the analytical solution. The dynamic characteristics and mode shapes of the ribbed plate are measured and compared to those obtained from the analytical solution and from finite element analysis (FEA). General good agreements are found between the results. Discrepancies between the computational and experimental results at low and high frequencies are also discussed. Explanations are offered in the study to disclose the mechanism causing the discrepancies. The dependency of the dynamic response of the ribbed plate on the distance between the excitation force and the rib is also investigated experimentally. It confirms the findings disclosed in a previous analytical study [T.R. Lin, J. Pan, A closed form solution for the dynamic response of finite ribbed plates, Journal of the Acoustical Society of America 119 (2006) 917-925] that the vibration response of a clamped ribbed plate due to a point force excitation is controlled by the plate stiffness when the source is more than a quarter plate bending wavelength away from the rib and from the plate boundary. The response is largely affected by the rib stiffness when the source location is less than a quarter bending wavelength away from the rib.

Lin, Tian Ran

2012-02-01

80

Experimental-theoretical investigation of the vibration characteristics of rotating composite box beams  

NASA Astrophysics Data System (ADS)

The objective of the study was to predict the effect of elastic couplings on the free vibration characteristics of thin-walled composite box beams and to correlate the results with experimental data. The free vibration characteristics of coupled thin-walled composite beams under rotation were determined using the Galerkin method. The theoretical results were found to be in satisfactory agreement with experimental data obtained for graphite/epoxy, kevlar/epoxy, and glass/epoxy composite beams in an in-vacuo test facility at different rotational speeds.

Chandra, Ramesh; Chopra, Inderjit

1992-08-01

81

Simulation Research on Vehicle Semiactive Vibration Isolation System  

Microsoft Academic Search

The simulation model of railway vehicle semi-active vibration isolation system is constructed by application of Matlab \\/ Simulink software, and the dynamics simulation on railway vehicle semi-active vibration isolation system is carried out. In the case of random input, the vibration isolation characteristics (such as distance of vibration isolation, vibration acceleration response variance) of railway vehicle are computed and analyzed,

Hongjie Duan; Hao Tao

2010-01-01

82

Vibration Characteristics of Piezoelectric Lead Zirconate Titanate by Fluid Flow in Intravascular Oxygenator  

NASA Astrophysics Data System (ADS)

In this paper, we describe the enhancement in oxygen transfer rate in hollow-fiber-membrane (HFM) modules using a plumbum piezoelectric lead zirconate titanate (PZT) actuator and a piezoelectric poly vinylidene fluoride (PVDF) sensor. We developed a vibrating intravascular lung assist device (VIVLAD) for patients having chronic respiratory problems and performed experiments on hydrodynamic flow through a bundle of sinusoidal vibrating hollow fibers. These modules were used to provide some insight into how wall vibrations might enhance the performance of an intravascular lung assist device. The experimental design and procedure are then applied to the fabrication of a device used to assess the effectiveness of membrane vibrations. The test section was a cylindrical duct with an inner diameter of 30 mm. The flow rate was controlled by a pump and monitored by a built-in flowmeter. The vibration apparatus was composed of a piezovibrator, a function generator, and a power amplifier. The direction of vibration was radial to the fluid flow. Gas flow rates of up to 6 L/min through 120-cm-long hollow fibers were achieved by exciting the piezovibrator. The time and frequency responses of PVDF sensors were investigated through various frequencies in VIVLAD. In these devices, the flow of blood and the source of oxygen were separated by a semipermeable membrane that allows oxygen and carbon dioxide to diffuse into and out of the fluid, respectively. Results of the experiments have shown that a vibrating intravascular lung assist device performs effectively.

Kim, Gi?Beum; Hong, Chul?Un; Kwon, Tae?Kyu

2006-04-01

83

Vibration testing based on impulse response excited by laser ablation  

NASA Astrophysics Data System (ADS)

This paper proposes an innovative vibration testing method based on impulse response excited by laser ablation. In conventional vibration testing using an impulse hammer, high-frequency elements of over tens of kilohertz are barely present in the excitation force. A pulsed high-power YAG laser is used in this study for producing an ideal impulse force on a structural surface. Illuminating a point on a metal with the well-focused YAG laser, laser ablation is caused by generation of plasma on the metal. As a result, an ideal impulse excitation force generated by laser ablation is applied to the point on the structure. Therefore, it is possible to measure high-frequency FRFs due to the laser excitation. A water droplet overlay on the metal is used to adjust the force magnitude of laser excitation. An aluminum block that has nine natural frequencies below 40 kHz is employed as a test piece. The validity of the proposed method is verified by comparing the FRFs of the block obtained by the laser excitation, impulse hammer, and finite element analysis. Furthermore, the relationship between accuracy of FRF measurements and sensitivity of sensors is investigated.

Kajiwara, Itsuro; Hosoya, Naoki

2011-10-01

84

Non-linear dual-axis biodynamic response to vertical whole-body vibration  

Microsoft Academic Search

Seated human subjects have been exposed to vertical whole-body vibration so as to investigate the non-linearity in their biodynamic responses and quantify the response in directions other than the direction of excitation. Twelve males were exposed to random vertical vibration in the frequency range 0.25–25Hz at four vibration magnitudes (0.125, 0.25, 0.625, and 1.25ms?2r.m.s.). The subjects sat in four sitting

N. Nawayseh; M. J Griffin

2003-01-01

85

The vibration characteristics of a tensioned plate containing a fatigue crack  

Microsoft Academic Search

The vibration characteristics of a simplified model of an aircraft fuselage panel, containing a fatigue crack, are obtained using the finite element displacement method. This study is a preliminary to the determination of the fluctuating stresses at the tip of the crack. The model considered is a rectangular plate subject to a tensile load representing the fuselage hoop stress. The

M. Petyt

1968-01-01

86

Dynamic characteristics and human perception of vibration aboard a military propeller aircraft  

Microsoft Academic Search

This study investigated the dynamic characteristics and human perception of higher-frequency multi-axis vibration associated with a military propeller aircraft environment. Triaxial accelerations were measured at the interfaces between the occupant and aircraft seat surface (seat pan and seat back) to evaluate and compare the effects of the aircraft seat fitted with different cushions. While all cushions showed a significant reduction

Suzanne D. Smith

2008-01-01

87

Vibration-Absorbing Characteristics of Metal-Polymer Shells (Abstract Only),  

National Technical Information Service (NTIS)

The vibration absorbing characteristics of metal shells with elastic polymer damper coatings are calculated by the energy method on the basis of Kirchoff-Love hypotheses. All layers of the multilayer coating are assumed to cooperate so that all strain com...

V. M. Chernyshev

1987-01-01

88

Some constructions and characteristics of rod-type piezoelectric ultrasonic motors using longitudinal and torsional vibrations  

Microsoft Academic Search

Ultrasonic motors using longitudinal and torsional motions of rod vibrators have previously been proposed. Several motor constructions, whose forms are different from the previous ones, are proposed and their characteristics are experimentally examined in order to develop the ultrasonic motors of this type; that is, they are expected to have much different uses, according to how their forms are modified.

Yoshiro Tomikawa; Kazunari Adachi; Manabu Aoyagi; Tadaatsu Sagae; Takehiro Takano

1992-01-01

89

Bone cell responses to high-frequency vibration stress: does the nucleus oscillate within the cytoplasm?  

Microsoft Academic Search

Mechanosensing by cells directs changes in bone mass and structure in response to the chal- lenges of mechanical loading. Low-amplitude, high- frequency loading stimulates bone growth by enhancing bone formation and inhibiting disuse osteoporosis. However, how bone cells sense vibration stress is unknown. Hence, we investigated bone cell responses to vibration stress at a wide frequency range (5-100 Hz). We

Rommel G. Bacabac; Theo H. Smit; Jack J. W. A. Van Loon; Behrouz Zandieh Doulabi; Marco Helder; Jenneke Klein-Nulend

2006-01-01

90

Methods for deriving a representative biodynamic response of the hand-arm system to vibration  

NASA Astrophysics Data System (ADS)

Vibration-induced biodynamic responses (BR) of the human hand-arm system measured with subjects participating in an experiment are usually arithmetically averaged and used to represent their mean response. The mean BR data reported from different studies are further arithmetically averaged to form the reference mean response for standardization and other applications. The objectives of this study are to clarify whether such a response-based averaging process could significantly misrepresent the characteristics of the original responses, and to identify an appropriate derivation method. The arithmetically averaged response was directly compared with the response derived from a property-based method proposed in this study. Two sets of reported mechanical impedance data measured at the fingers and the palms of the hands were used to derive the models required for the comparison. This study found that the response-based arithmetic averaging could generate some systematic errors. The range of the subjects’ natural frequencies in each resonance mode, the mode damping ratio, and the number of subjects participating in the experiment are among the major factors influencing the level of the errors. An effective and practical approach for reducing the potential for error is to increase the number of subjects in the BR measurement. On the other hand, the property-based derivation method can be generally used to obtain the representative response, but it is less efficient than the response-based derivation method.

Dong, Ren G.; Welcome, Daniel E.; McDowell, Thomas W.; Wu, John Z.

2009-09-01

91

Biodynamic characteristics of upper limb reaching movements of the seated human under whole-body vibration.  

PubMed

Simulation of human movements is an essential component for proactive ergonomic analysis and biomechanical model development (Chaffin, 2001). Most studies on reach kinematics have described human movements in a static environment, however the models derived from these studies cannot be applied to the analysis of human reach movements in vibratory environments such as in-vehicle operations. This study analyzes three-dimensional joint kinematics of the upper extremity in reach movements performed in static and specific vibratory conditions and investigates vibration transmission to shoulder, elbow, and hand along the body path during pointing tasks. Thirteen seated subjects performed reach movements to five target directions distributed in their right hemisphere. The results show similarities in the characteristics of movement patterns and reach trajectories of upper body segments for static and dynamic environments. In addition, vibration transmission through upper body segments is affected by vibration frequency, direction, and location of the target to be reached. Similarities in the pattern of movement trajectories revealed by filtering vibration-induced oscillations indicate that coordination strategy may not be drastically different in static and vibratory environments. This finding may facilitate the development of active biodynamic models to predict human performance and behavior under whole body vibration exposure. PMID:22814094

Kim, Heon-Jeong; Martin, Bernard J

2012-07-06

92

Individual Variability in Human Response to Whole-body Vibration  

Microsoft Academic Search

This paper reports an experiment to obtain an equal sensation contour for whole-body vibration using an entirely new, but demonstrably valid and reliable, paradigm. Instead of requiring subjects to equate variable vibration stimuli of different frequencies with a fixed standard stimulus, the paradigm employed a series of matching tasks with the standard stimulus being produced by the subject in the

D. J. OBORNE; D. A. HUMPHREYS

1976-01-01

93

Mechanical and Vibration Characteristics of Laminated Composite Plates Embedding Shape Memory Alloy Superelastic Wires  

NASA Astrophysics Data System (ADS)

Currently, there is a great interest in the study of shape memory alloy (SMA) composites, since SMA wires with a small diameter have become commercially available. Many potential uses have been found for SMA composites in shape control, vibration control, and for the realization of structures with improved damage tolerance. In this work, two types of SMA-hybridized composites are presented for investigating the mechanical and vibration characteristics. The first one contains unidirectional superelastic SMA wires, while the other has been realized with embedded knitted SMA layers. The samples from these laminates have been tested according to “Charpy method” (ASTM D256) and static flexural test method (ASTM D790) to evaluate the influence of the integration of thin superelastic SMA wires on the impact behavior and the mechanical properties of the hybrid composites. Moreover, since the SMA wires are expected to give damping capacity, by measuring the vibration mode of a clamped cantilever using laser vibrometry, the influence of both SMA arrangements on the vibration characteristics has been investigated. Finally, further tests have been carried out on composite panels realized by embedding unidirectional steel wires to distinguish the influence of the martensitic transformation from the pure introduction of a metallic wire into the polymeric matrix.

Pappadà, Silvio; Gren, Per; Tatar, Kourosh; Gustafson, Tord; Rametta, Rocco; Rossini, Ettore; Maffezzoli, Alfonso

2009-08-01

94

Response of vibration-isolated object to ground motions with intense vertical accelerations  

Microsoft Academic Search

This paper reports the results of shaking table tests performed to assess the response of an object placed on a vibration isolator to intense ground motions whose peak accelerations are close to or over the gravity acceleration in both vertical and horizontal directions. The passive vertical and horizontal vibration isolator, developed by the authors, has rolling load-bearing elements and constant-force

Yoshikazu Araki; Shinya Kawabata; Takehiko Asai; Takeshi Masui

2011-01-01

95

Antagonist motor responses correlate with kinesthetic illusions induced by tendon vibration  

Microsoft Academic Search

In humans, vibration applied to muscle tendons evokes illusory sensations of movement that are usually associated with an\\u000a excitatory tonic response in muscles antagonistic to those vibrated (antagonist vibratory response or AVR). The aim of the\\u000a present study was to investigate the neurophysiological mechanisms underlying such a motor response. For that purpose, we\\u000a analyzed the relationships between the parameters of

Sarah Calvin-Figuière; Patricia Romaiguère; Jean-Claude Gilhodes; Jean-Pierre Roll

1999-01-01

96

Simplified formulae to investigate flexural vibration characteristics of piezoelectric tubes in ultrasonic micro-actuators.  

PubMed

Based on the Rayleigh energy theory combining with Timoshenko beam model, the flexural vibration characteristics of piezoelectric tubes in ultrasonic micro-actuators are investigated. Additionally, the simplified formulae are derived to study the fundamental flexural resonance frequencies of the piezoelectric tubes with free-free ends and cantilevers. By changing the sizes of the tubes and the mass loads at the free ends, the variations of the flexural resonance frequencies of the piezoelectric tubes and cantilevers are calculated theoretically. To verify accuracy of the simplified formulae, by changing the lengths of the tubes and the mass loads the flexural resonance frequencies of the piezoelectric tube with free-free ends are measured experimentally. The theoretical results agree well with the experimental measurements, which demonstrate that the simplified formulae are accurate and effective for analyzing the flexural vibration characteristics of the piezoelectric tubes in the ultrasonic micro-actuators. PMID:19818979

Zhang, Hui; Zhang, Shu-Yi; Fan, Li

2009-09-18

97

Adaptive characteristics of the magnetostrictive alloy, Terfenol-D, for active vibration control  

SciTech Connect

A recently developed magnetostrictive material is applied to development of a class of adaptive actuators for vibration control. The material offers the highest strain and energy density of any commercially available material. This paper reviews the material properties of the alloy with emphasis on characteristics which adapt to external variables. Performance data of some basic actuators and a discussion of essential design elements is presented, along with engineering data of value to designers of 'smart' actuators. 12 refs.

Goodfriend, M.J.; Shoop, K.M. (Etrema Products, Inc., Ames, IA (United States))

1992-04-01

98

Flow-induced vibration characteristics of the BWR\\/5-201 jet pump  

Microsoft Academic Search

A General Electric boiling water reactor BWR\\/5-201 jet pump was tested for flow-induced vibration (FIV) characteristics in the Large Steam Water Test Facility at Moss Landing, CA, during the period June-July 1978. High level periodic FIV were observed at reactor operating conditions (1027 psia, 532°F and prototypical flow rates) for the specific single jet pump assembly tested. High level FIV

1982-01-01

99

A study on micro-grooving characteristics of planar lightwave circuit and glass using ultrasonic vibration cutting  

Microsoft Academic Search

Micro-grooving of brittle materials such as glass, which are widely used as optical components, was accomplished using a polycrystalline diamond tool with ultrasonic vibration. To determine the cutting characteristics of brittle materials, the machining system with an ultrasonic vibration tool was built. Experiments for micro-grooving of the planar lightwave circuits (PLCs) and glass were performed and their shapes were measured

Jun-Seok Lee; Deug-Woo Lee; Yoong-Ho Jung; Woo-Seop Chung

2002-01-01

100

Evaluating longitudinal vibration characteristics of bonded strands embedded in prestressed concrete beams by a system identification approach  

Microsoft Academic Search

This study is to investigate the wire rope governing equation in order to establish the longitudinal vibration characteristics of bonded PSC strands. For this purpose, the longitudinal vibration tests have been conducted for six bonded PSC specimens with the different stress levels. Subsequently, the wave velocities of the strands have been estimated from the test results. Then, a sensitivity-based system

Byeong Hwa Kim; Jung Bum Jang; Hong Pyo Lee; Do Hyung Lee

101

Frequency response of distributed fiber-optic vibration sensor based on nonbalanced Mach-Zehnder interferometer  

NASA Astrophysics Data System (ADS)

We set up the analytical model for the frequency response of a distributed fiber-optic vibration sensor based on the nonbalanced Mach-Zehnder interferometer, the frequency response of which is related to both of the length difference of the delay fibers and the location of the vibration. In addition, a series of null frequencies, in which the vibration cannot be detected, is also found. The distributed fiber-optic vibration sensor with the delay fiber of 25 km and the sensing fiber of 10 km is built experimentally. Two null frequencies of 8013 Hz and 5011 Hz, which are induced from the delay fibers and the location of vibration respectively, are obtained. The results can serve as an important guidance for designing the sensor.

Wei, Pu; Shan, Xuekang; Sun, Xiaohan

2013-01-01

102

Optimisation of the vibrational response of ultrasonic cutting systems  

NASA Astrophysics Data System (ADS)

This paper provides an account of an investigation into possible dynamic interactions between two coupled non-linear sub-systems, each possessing opposing non-linear overhang characteristics in the frequency domain in terms of positive and negative cubic stiffnesses. This system is a two-degree-of-freedom Duffing oscillator in which certain non-linear effects can be advantageously neutralised under specific conditions. This theoretical vehicle has been used as a preliminary methodology for understanding the interactive behaviour within typical industrial ultrasonic cutting components. Ultrasonic energy is generated within a piezoelectric exciter, which is inherently non-linear, and which is coupled to a bar- or block-horn, and to one or more material cutting blades, for example. The horn/blade configurations are also non-linear, and within the whole system there are response features which are strongly reminiscent of positive and negative cubic stiffness effects. The two-degree-of-freedom model is analysed and it is shown that a practically useful mitigating effect on the overall non-linear response of the system can be created under certain conditions when one of the cubic stiffnesses is varied. It has also been shown experimentally that coupling of ultrasonic components with different non-linear characteristics can strongly influence the performance of the system and that the general behaviour of the hypothetical theoretical model is indeed borne out in practice. Further experiments have shown that a multiple horn/blade configuration can, under certain circumstances, display autoparametric responses based on the forced response of the desired longitudinal mode parametrically exciting an undesired lateral mode. Typical autoparametric response phenomena have been observed and are presented at the end of the paper.

Cartmell, M. P.; Lim, F. C. N.; Cardoni, A.; Lucas, M.

2005-10-01

103

Nonlinear subjective and dynamic responses of seated subjects exposed to horizontal whole-body vibration  

NASA Astrophysics Data System (ADS)

The effect of the magnitude of fore-and-aft and lateral vibration on the subjective and mechanical responses of seated subjects has been investigated experimentally using simultaneous measurements of relative discomfort and apparent mass. Twelve male subjects were exposed to sinusoidal vibration at nine frequencies (between 1.6 and 10 Hz) at four magnitudes (in the range 0.125-1.0 m s-2 r.m.s.) in both horizontal directions (fore-and-aft and lateral). The method of magnitude estimation was used to estimate discomfort relative to that caused by a 4 Hz reference vibration in the same axis. The apparent mass was calculated from the acceleration and the applied force so as to quantify the mechanical response of the body. With each direction of excitation, the apparent mass was normalised by dividing it by the apparent mass obtained at 4 Hz, so that the mechanical responses could be compared with the subjective responses. The relative discomfort and the normalised apparent mass were similarly affected by the frequency and magnitude of vibration, with significant correlations between the relative discomfort and the normalised apparent mass. The results indicate that the discomfort caused by horizontal whole-body vibration is associated with the apparent mass in a frequency range where motion of the whole body is dominant. In this frequency range, the nonlinear subjective responses may be attributed, at least in part, to the nonlinear dynamic responses to horizontal whole-body vibration.

Subashi, G. H. M. J.; Nawayseh, N.; Matsumoto, Y.; Griffin, M. J.

2009-03-01

104

Hydrodynamic Impact-Induced Vibration Characteristics of a Uniform Euler-Bernoulli Beam  

Microsoft Academic Search

A hydroelastic analysis of slam-induced beam vibration is presented. The objective of the paper is to provide response spectra for transient water-structure dynamics subject to typical impact loads and time scales. Assuming small deflections of the\\u000a Euler-Bernoulli beam, normal mode summation is used to calculate the dynamic deflections in space and time. The modal governing\\u000a differential equation is non-dimensionalized in

Nabanita Datta; Dae-Hyun Kim; Armin W. Troesch

105

ATOMIC AND MOLECULAR PHYSICS: Ultrafast multiplex CARS investigation of vibrational characteristics in chloroform and PMMA  

NASA Astrophysics Data System (ADS)

This paper demonstrates the femtosecond time-resolved coherent anti-Stokes Raman scattering by using folded BOXCARS geometry where an ultrashort broadband coherent white light continuum was used as Stokes pulse, and carries out the non-contact detection at long distance. The CARS signal is so easy to be detected that it can be seen even by nude eye. The C-H bonds of chloroform or PMMA were detected and the vibration modes belonging to the side chain and the main chain in PMMA were also compared. Their vibrational characteristics involved decay process and quantum beating were discussed. This modified CARS experimental technique could make up the deficiency of traditional CARS technique.

Wang, Ying-Hui; Peng, Ya-Jing; He, Xing; Song, Yun-Fei; Yang, Yan-Qiang

2009-04-01

106

Teacher Characteristics for Culturally Responsive Pedagogy  

ERIC Educational Resources Information Center

|Culturally responsive pedagogy, as defined by one of the most prominent authors in the field, Geneva Gay (2002), is "using the cultural characteristics, experiences, and perspectives of ethnically diverse students as conduits for teaching them more effectively". Culturally responsive pedagogy can be thought of, then, as teaching practices that…

Rychly, Laura; Graves, Emily

2012-01-01

107

ADAPTIVE RESPONSES OF HUMAN SKELETAL MUSCLE TO VIBRATION EXPOSURE  

Microsoft Academic Search

Summary The aim of this study was to investigate the effects of whole-body vibrations (WBV) on the mechanical behaviour of human skeletal muscle. For this purpose, six female volleyball players at national level were recruited voluntarily. They were tested with maximal dynamic leg press exercise on a slide machine with extra loads of 70, 90, 110 and 130 kg. After

C. Bosco; R. Colli; E. Introini; M. Cardinale; M. Iacovelli; A. Madella; J. Tihanyi; A. Viru

1999-01-01

108

Model-based dynamic compensation of load cell response in weighing machines affected by environmental vibrations  

NASA Astrophysics Data System (ADS)

This work proposes and validates experimentally a model-based scheme for the compensation of environmental vibrations affecting load cell measurements in automatic weighing machines. Weighing machines are often adversely affected by low frequency vibrations which may arise from the coupled effects of machine frame flexibility and the excitation induced by internal (inertial) or external (impact) vibration sources. These vibrations are generally named “environmental vibrations”, since they seem to arise from the environment around the machine. Environmental vibrations have a detrimental effect on load cell responses and can in turn deteriorate machine performances. It is usually ineffective to try overcoming this problem by low-pass filtering load cell measurements: low cut-off frequencies usually downgrade machine speed by both introducing delay and increasing filtered signal rise time. Since automatic weighing machines need to operate at ever increasing speed, alternative approaches must be investigated. In this work it is suggested to make use of the mechanical models of the weighing machine and the load cells to process supplementary accelerometer measurements and compute an effective compensation of the effect of environmental vibrations on load cell response. The technique is here applied to a multi-head weighing machine in order to prove its effectiveness and implementability in industrial devices with real-time controllers.

Boschetti, Giovanni; Caracciolo, Roberto; Richiedei, Dario; Trevisani, Alberto

2013-01-01

109

The role of helicopter noise-induced vibration and rattle in human response  

NASA Astrophysics Data System (ADS)

The role of perceived building vibrations and rattle in human response to helicopter noise (in terms of percentage of population highly annoyed) was studied using the A-weighting and C-weighting to assess response. Test participants were placed in a wood-frame home, a mobile home, or outdoors. To create a wide range of single-event flyby SELs, the helicopter's slant distance from the test structures was varied. It was found that when the noise induced noticeable vibrations, negative response increased significantly. However, neither A-weighting nor C-weighting could properly assess human response when the helicopter noise excited high levels of vibration and rattle. The presence or absence of high levels of noise-induced vibration was strongly dependent on the helicopter's slant distance: slant distances shorter than 500 ft virtually ensured high levels of noise-induced vibration and rattles, whereas at slant distances in excess of 1000 ft there occurred little or no vibration or rattle.

Schomer, Paul D.; Neathammer, Robert D.

1987-04-01

110

Nonlinear response of vibrational excitons: Simulating the two-dimensional infrared spectrum of liquid water  

PubMed Central

A simulation formalism for the nonlinear response of vibrational excitons is presented and applied to the OH stretching vibrations of neat liquid H2O. The method employs numerical integration of the Schrödinger equation and allows explicit treatment of fluctuating transition frequencies, vibrational couplings, dipole moments, and the anharmonicities of all these quantities, as well as nonadiabatic effects. The split operator technique greatly increases computational feasibility and performance. The electrostatic map for the OH stretching vibrations in liquid water employed in our previous study [A. Paarmann et al., J. Chem. Phys. 128, 191103 (2008)] is presented. The two-dimensional spectra are in close agreement with experiment. The fast 100 fs dynamics are primarily attributed to intramolecular mixing between states in the two-dimensional OH stretching potential. Small intermolecular couplings are sufficient to reproduce the experimental energy transfer time scales. Interference effects between Liouville pathways in excitonic systems and their impact on the analysis of the nonlinear response are discussed.

Paarmann, A.; Hayashi, T.; Mukamel, S.; Miller, R. J. D.

2009-01-01

111

Characteristics of ultrasonic vibration-assisted ductile mode cutting of tungsten carbide  

Microsoft Academic Search

In this study, investigations were carried out to evaluate the characteristics of ultrasonic vibration-assisted cutting of\\u000a tungsten carbide material using a CNC lathe with CBN tool inserts. The cutting forces were measured using a three-component\\u000a dynamometer, and the machined workpiece surfaces and chip formation were examined using a SEM. The experimental results showed\\u000a that the radial force F\\u000a \\u000a x\\u000a was

K. Liu; X. P. Li; M. Rahman

2008-01-01

112

The Influence of Ethanol–Gasoline Blends on Spark Ignition Engine Vibration Characteristics and Noise Emissions  

Microsoft Academic Search

Engine vibration characteristics and noise emission of a two stroke spark ignition engine were investigated by using blends of ethanol–gasoline–oil (25% E–70% G–5% O and 50% E–45% G–5% O) and pure gasoline. Engine test conditions were 0.86 kW (5.5 Nm) at 1,500 rpm, 1.25 kW (6.0 Nm) at 2,000 rpm, and 1.83 kW (7.0 Nm) at 2,500 rpm. A high

A. Keskin

2010-01-01

113

Comparison between Deflection and Vibration Characteristics of Rectangular and Trapezoidal profile Microcantilevers  

PubMed Central

Arrays of microcantilevers are increasingly being used as physical, biological, and chemical sensors in various applications. To improve the sensitivity of microcantilever sensors, this study analyses and compares the deflection and vibration characteristics of rectangular and trapezoidal profile microcantilevers. Three models of each profile are investigated. The cantilevers are analyzed for maximum deflection, fundamental resonant frequency and maximum stress. The surface stress is modelled as in-plane tensile force applied on the top edge of the microcantilevers. A commercial finite element analysis software ANSYS is used to analyze the designs. Results show paddled trapezoidal profile microcantilevers have better sensitivity.

Ansari, Mohd. Zahid; Cho, Chongdu; Kim, Jooyong; Bang, Booun

2009-01-01

114

Variation in Neuromuscular Responses during Acute Whole-Body Vibration Exercise  

Microsoft Academic Search

ABERCROMBY, A. F. J., W. E. AMONETTE, C. S. LAYNE, B. K. MCFARLIN, M. R. HINMAN, and W. H. PALOSKI. Variation in Neuromuscular Responses during Acute Whole-Body Vibration Exercise. Med. Sci. Sports Exerc., Vol. 39, No. 9, pp. 1642-1650, 2007. Purpose: Leg muscle strength and power are increased after whole-body vibration (WBV) exercise. These effects may result from increased neuromuscular

ANDREW F. J. ABERCROMBY; WILLIAM E. AMONETTE; CHARLES S. LAYNE; BRIAN K. MCFARLIN; MARTHA R. HINMAN; WILLIAM H. PALOSKI

2007-01-01

115

Head position-based electrotactile tongue biofeedback affects postural responses to Achilles tendon vibration in humans  

Microsoft Academic Search

The purpose of the present experiment was to investigate whether postural responses to ankle proprioceptive perturbation Achilles\\u000a tendon vibration were affected by the availability of augmented sensory information about head orientation\\/motion with respect\\u000a to gravitational vertical, i.e., normally provided by the vestibular system. To achieve this goal, ten standing subjects were\\u000a exposed to Achilles tendon vibration in two No Biofeedback

Nicolas Vuillerme; Rémy Cuisinier

2008-01-01

116

Prediction of vibration amplitude from machining parameters by response surface methodology in end milling  

Microsoft Academic Search

Decreasing vibration amplitude during end milling process reduces tool wear and improves surface finish. Mathematical model\\u000a has been developed to predict the acceleration amplitude of vibration in terms of machining parameters such as helix angle\\u000a of cutting tool, spindle speed, feed rate, and axial and radial depth of cut. Central composite rotatable second-order response\\u000a surface methodology was employed to create

P. S. Sivasakthivel; V. Velmurugan; R. Sudhakaran

2011-01-01

117

Nonlinear finite element analysis of the vibration characteristics of the maxillary central incisor related to periodontal attachment  

Microsoft Academic Search

The vibration characteristics of a maxillary central incisor were investigated by using the finite element method (FEM) according\\u000a to nonlinear behavior of the human periodontal ligament (PDL). The effect of alveolar bone loss was also studied to obtain\\u000a the relationship between the vibration property of the tooth in the periodontal system and the level of periodontal attachment\\u000a for assessing the

Haitao Xin; Yulong Li; Lingcheng Zhao; Weiguo Guo

2009-01-01

118

Vibration characteristics of thin rotating cylindrical shells with various boundary conditions  

NASA Astrophysics Data System (ADS)

An analysis is presented for the vibration characteristics of thin rotating cylindrical shells with various boundary conditions by use of Fourier series expansion method. Based on Sanders’ shell equations, the governing equations of motion which take into account the effects of centrifugal and Coriolis forces as well as the initial hoop tension due to rotating are derived. The displacement field is expressed as a product of Fourier series expressions which represents the axial modal displacements and trigonometric functions which represents the circumferential modal displacements. Stokes’ transformation is employed to derive the derivatives of the Fourier series expressions. Then, through the process of formula derivation, an explicit expression of the exact frequency equation can be obtained for a thin rotating cylinder with classical boundary conditions of any type. Once the frequency equation has been determined, the frequencies are calculated numerically. To validate the present analysis, comparisons between the results of the present method and previous studies are performed and very good agreement is achieved. Finally, the method is applied to investigate the vibration characteristics of thin rotating cylindrical shells under various boundaries, and the results are presented.

Sun, Shupeng; Chu, Shiming; Cao, Dengqing

2012-08-01

119

Vibration characteristics of piezoelectric fiber composites under thermo-electro-mechanical loadings  

NASA Astrophysics Data System (ADS)

In this paper, vibration characteristics of piezoelectric fiber composite beams are presented. An asymptotic method based on virtual work principle is introduced first. The primary variables in thermo-electro-mechanical problems are asymptotically expanded in terms of the small parameter, which is done by taking the geometric slenderness of the beams. This subsequently renders a set of recursive virtual works at each order, in which the virtual works are separated into two parts: 2D microscopic problems and 1D macroscopic problems. These microscopic and macroscopic problems are systematically associated with each other, and thus the boundary conditions are affected by both of them. Cantilever beams under multiphysics environment are taken as a test-bed in order to illustrate the significance of edge effects and asymptotical correctness to the vibration characteristics of the beams. For the displacement prescribed boundary such as the clamped boundary, the stress weighted average conditions are applied to obtain the accurate prediction, which are known to be a good approximation (possibly the best candidate up to date).

Kim, Jun-Sik

2011-11-01

120

Response characteristics of a fractional oscillator  

Microsoft Academic Search

The integral equation of motion of a driven fractional oscillator is obtained by generalizing the corresponding equation of motion of a driven harmonic oscillator to include integrals of arbitrary order according to the methods of fractional calculus. The Green's function solution for the fractional oscillator is obtained in terms of Mittag-Leffler functions using Laplace transforms. The response and resonance characteristics

B. N. Narahari Achar; John W. Hanneken; T. Clarke

2002-01-01

121

Response characteristics of a fractional oscillator  

Microsoft Academic Search

The integral equation of motion of a driven fractional oscillator is obtained by generalizing the corresponding equation of motion of a driven harmonic oscillator to include integrals of arbitrary order according to the methods of fractional calculus. The Green's function solution for the fractional oscillator is obtained in terms of Mittag–Leffler functions using Laplace transforms. The response and resonance characteristics

B. N. Narahari Achar; John W. Hanneken; T. Clarke

2002-01-01

122

Measurement and vibration control of dynamic characteristics of feed table for machine tool  

Microsoft Academic Search

Vibration control of feed table on NC positioning control is one of the most important problems in machine tools, because the amplitude of vibration itself causes the degradation of machined profiles and surface roughness. Previous studies looked at the low frequency range in which conventional NC feed table responds and deal with the vibration problem while positioning. Another vibration problem

Yoshitaka Morimoto; Yoshio Ichida; Ryunosuke Sato; T. Unno

2002-01-01

123

Dose-response relation for vascular disorders induced by vibration in the fingers of forestry workers.  

PubMed Central

OBJECTIVES--To study the relation between the prevalence of vascular disorders (white finger) and vibration exposure in a group of 222 forestry workers, of whom 164 (73.9%) had work experience limited to antivibration (AV) chain saws only and 58 (26.1%) had operated both non-AV and AV chain saws. METHODS--The chain saw operators and 195 control workers never exposed to hand transmitted vibration were interviewed with health and workplace assessment questionnaires. The diagnosis of vibration induced white finger (VWF) was made on the basis of subjective symptoms of finger blanching and the results of a cold test with plethysmographic measurement of systolic blood pressure of the finger. Vibration was measured on a representative sample of AV and non-AV chain saws. Daily vibration exposure was assessed as eight hour energy equivalent frequency weighted acceleration (A(8)). A lifetime vibration dose was estimated for each of the forestry workers. RESULTS--The overall prevalence of VWF among the forestry workers was 23.4%. The diagnosis of VWF was made in 13.4% of the forestry workers who handled only AV chain saws and in 51.7% of those who had also operated non-AV chain saws in the past. Raynaud's phenomenon was found in 2.6% of the controls. In the forestry workers, the risk for VWF showed positive increments with each increment of vibration dose, suggesting a monotonic dose-response relation. The responsiveness to cold in the digital arteries of the forestry workers was also found to increase with increasing vibration dose and severity of VWF. The estimated relation between VWF and vibration exposure showed that the expected prevalence of VWF increased almost linearly to either A(8) (with exposure duration unchanged) or the number of years of exposure (with equivalent acceleration unchanged). CONCLUSIONS--In this study of VWF among forestry workers, the estimated dose-response relation showed that if the magnitude of vibration acceleration is doubled, the total duration of exposure should be halved to produce an equivalent effect. On the basis of the assessment of vibration exposure, the estimated risk for VWF in the study population was found to be lower than that predicted by the international standard ISO 5349. These findings suggest a revision of the risk estimates for VWF currently provided by ISO 5349.

Bovenzi, M; Franzinelli, A; Mancini, R; Cannava, M G; Maiorano, M; Ceccarelli, F

1995-01-01

124

Vibrational Response of Au-Ag Nanoboxes and Nanocages to Ultrafast Laser-Induced Heating  

PubMed Central

Time-resolved spectroscopy has been used to investigate the vibrational properties of hollow cubic nanoparticles: Au-Ag nanoboxes and nanocages. In these experiments laser-induced heating was used to coherently excite the breathing vibrational modes of the particle. The vibrational periods scale with the edge length of the particle, and the nanocages and nanoboxes showing equivalent responses despite a large difference in their morphology. The measured vibrational periods are compared to finite element calculations, where the particles are modeled as a hollow cube, with the principle crystal axes parallel to the sides of the cube. Very good agreement is obtained between the calculations and the experimental data, with the experimental frequencies being slightly lower than the calculated values (by ? 7 %). These results demonstrate the importance of accurately modeling the particles in order to interpret experimental data.

Petrova, Hristina; Lin, Chien-Hua; Hu, Min; Chen, Jingyi; Siekkinen, Andrew R.; Xia, Younan; Sader, John E.; Hartland, Gregory V.

2008-01-01

125

Transient response of piezoelectric thin-film vibration sensor under pulse excitation  

NASA Astrophysics Data System (ADS)

We present an analytical model to describe the transient response of a piezoelectric thin-film vibration sensor under pulse excitation. The structure of the thin-film vibration sensor consists of four suspended flexural piezoelectric lead zirconate titanate-on-silicon beam transducers and a central seismic mass. The model takes into account the effect of device geometry and materials properties of the piezoelectric thin film. The relationships between the dynamic behavior and voltage sensitivity with the device's structure are established. It is found that with the increase of initial vibration magnitude U0 and reciprocal time constant ? (?=1/?) of the excitation, the maximum voltage sensitivity increases, and the maximum output voltage decreases with the increase of the resonance frequency. When damping is taken into account, the output voltage of the device under pulse excitation is simply an exponentially decaying function of time. The results can be readily applied for design and fabrication of the on-chip vibration sensor or accelerometer.

Yang, Zhaochun; Wang, Qing-Ming

2006-01-01

126

Non-linear dual-axis biodynamic response to fore-and-aft whole-body vibration  

NASA Astrophysics Data System (ADS)

Seated subjects have participated in two experiments with fore-and-aft whole-body vibration to investigate dynamic responses at the seat and footrest in the direction of vibration and in other directions. In the first experiment, 12 males were exposed to fore-and-aft random vibration (0.25 20 Hz) at four magnitudes (0.125, 0.25, 0.625, and 1.25 m s-2 rms) while sitting on a seat with no backrest in four postures with varying foot heights to produce differing thigh contact with the seat (feet hanging, feet supported with maximum thigh contact, feet supported with average thigh contact, and feet supported with minimum thigh contact). In the second experiment, six subjects were exposed to three vibration magnitudes (0.125, 0.25, 0.625 m s-2 rms) in the average thigh contact posture, both with and without a rigid backrest. Forces were measured in the vertical, fore-and-aft, and lateral directions on the supporting seat surface (in the first experiment) and in the fore-and-aft and vertical directions at the footrest (in the second experiment). On the seat, there were three vibration modes in the fore-and-aft apparent mass on the seat at frequencies below 10 Hz in all postures (around 1 Hz, between 1 and 3 Hz, and between 3 and 5 Hz); large vertical forces were dependent on foot support while lateral forces were relatively small. At the feet, the fore-and-aft apparent mass showed a resonance between 3 and 5 Hz, which increased in frequency and magnitude when a backrest was used. The fore-and-aft vibration produced high vertical forces at the footrest. At frequencies below resonance, the backrest reduced vertical and fore-and-aft forces at the footrest. On the seat and the footrest, the forces showed a nonlinear characteristic that varied between postures. The presence of appreciable vertical forces indicate that during fore-and-aft excitation the body moved in two dimensions. It is concluded that forces in directions other than the direction of excitation should be taken into account when considering biodynamic responses to fore-and-aft whole-body vibration.

Nawayseh, N.; Griffin, M. J.

2005-04-01

127

Biodynamic response of the hand-arm system to vibration from an impact hammer and a grinder  

Microsoft Academic Search

The dynamic response of the hand\\/arm system due to exposure of two types of vibrations, one from an impact hammer and one from a grinder, were studied. The aim of the investigation was to study whether the dynamic response was dependent of the type of exposure and\\/or the frequency of the vibration. The dynamic responses studied were driving point impedance,

Steve Kihlberg

1995-01-01

128

Machinery vibration: Origins, impressions and cures  

SciTech Connect

The current trend toward high performance (speed, power, flow, etc.) and low eight are causing new machinery dynamics problems. Vibration diagnostics engineering of rotor-bearing-casing systems must consider both internal and external influences to effectively predict and diagnose these problems. It is assumed that machinery vibration data are free from ambiguity, error, conform to a standard and clearly identify the physical cause(s) responsible for vibration. Rotor vibration due to internal forces are described: unbalance force characteristics; response characteristics; and rules of rotor fundamental response. Rotor vibration due to external forces include: rotating aerodynamic stall; oil whirl; oil whip; structural resonance; vane/blade passing vibration; misalignment; rotor rubbing; gear mesh vibrations; and shaft crack. These are also discussed.

Haq, I. (Bechtel Petroleum Operations, Inc., Tupman, CA (United States))

1995-01-01

129

Suppression of Subsynchronous Vibrations Due to Aerodynamic Response to Surge in a Two-Stage Centrifugal Compressor with Air Foil Bearings  

Microsoft Academic Search

An investigation was conducted on the suppression of subsynchronous vibrations due to aerodynamic response to surge in a two-stage centrifugal compressor with air foil bearings. Unsteady aerodynamic response to surge caused excessive subsynchronous shaft vibration which might result in reduced bearing life. Notably, subsynchronous vibrations associated with rigid mode frequencies were more severe than any other subsynchronous vibrations. The objective

Y. B. Lee; T. H. Kim; C. H. Kim; N. S. Lee

2003-01-01

130

Flow-induced vibration characteristics of the BWR/5-201 jet pump  

SciTech Connect

A General Electric boiling water reactor BWR/5-201 jet pump was tested for flow-induced vibration (FIV) characteristics in the Large Steam Water Test Facility at Moss Landing, CA, during the period June-July 1978. High level periodic FIV were observed at reactor operating conditions (1027 psia, 532/sup 0/F and prototypical flow rates) for the specific single jet pump assembly tested. High level FIV of similar amplitude and character have been shown capable of damaging jet pump components and associated support hardware if allowed to continue unchecked. High level FIV were effectively suppressed in two special cases tested: (1) lateral load (>500 lb) at the mixer to diffuser slip joint; and (2) a labyrinth seal (5 small, circumferential grooves) on the mixer at the slip joint. Stability criteria for the particular jet pump tested were developed from test data. A cause-effect relationship between the dynamic pressure within the slip joint and the jet pump vibration was established.

LaCroix, L.V.

1982-09-01

131

Linear response analysis of vibrational resonance in over-damped systems  

NASA Astrophysics Data System (ADS)

The phenomenon whereby the response to a weak low-frequency input signal is maximized in an oscillatory system with additional high-frequency input signals of appropriate amplitude is known as vibrational resonance (VR). In this study, the occurrence of VR in over-damped systems is analytically and numerically explained in the framework of linear response theory. The origin of the large response of VR is shown to be the dynamical bifurcation caused by tuning the input signals.

Ichiki, Akihisa; Tadokoro, Yukihiro; Takanashi, Masaki

2012-09-01

132

Biodynamic response of the human body in the sitting position when subjected to vertical vibration  

NASA Astrophysics Data System (ADS)

Previous studies of the location of those areas in which the sensation of vibration is perceived under whole body vertical vibration have underlined the predominance of the relative movement between thorax and pelvis. Experiments were designed to explore systematically the transmissibility between the pelvis and thorax. These were supplemented by measurements of mechanical impedance of the body and absorbed power. To determine the body impedance, a procedure was developed to remove the effect of the load platform itself. Fifteen subjects were presented first with a swept sinusoidal vibration, and then with a broad band random vibration, to see how the wave form of the motion might affect the mechanical response of the body. The results obtained for the seat to thorax transmissibility suggest that within the range of vertical vibration investigated (1-10 Hz, 1.6 m/s2 r.m.s.) the human body in the sitting position can be modelled by a linear system with one or two degrees of freedom according to the subject. Data from the impedance function, which is a more complete description of the response of the body as a mechanical system, lead to systems with one further degree of freedom.

Donati, P. M.; Bonthoux, C.

1983-10-01

133

Simulation research on the dynamic characteristics of a novel electrohydraulic vibration exciter  

Microsoft Academic Search

The novel electrohydraulic vibration exciter consists of two-dimension servo control valve (abbr.2D valve) and double acting hydraulic cylinder. Vibration frequency and amplitude of electrohydraulic vibration exciters are controlled by the rotation and linear motion of the 2D valve spool respectively. The frequency of the 2D valve controlled vibration exciter is determined by the rotary speed and the number of grooves

Jiping Bai; Jian Ruan; Guoqiang Pan; Genghong Jiang

2009-01-01

134

Biodynamic Response at the Palm of the Human Hand Subjected to a Random Vibration  

Microsoft Academic Search

This study investigated the biodynamic response (BR) distributed at the palm of the hand subjected to a random vibration. Twelve male subjects were used in the experiment. Each subject applied three coupling actions (grip-only, push-only, and combined grip and push) on a simulated tool handle at three different levels (50, 75, and 100 N) of palm force. This study found

Ren G. DONG; Thomas W. McDOWELL; Daniel E. WELCOME

2005-01-01

135

Effects of layer thickness on the vibration response of a plate-fluid layer system  

Microsoft Academic Search

Dynamic interaction between the bending vibrations of a plate and a fluid layer is investigated by using analytical and experimental methods. The frequency response behavior of the coupled plate-fluid layer system is studied, with emphasis on the influence of the layer thickness. The effects of compressibility, viscosity, and inertia of the fluid are included in the analytical model. A critical

T. Onsay

1993-01-01

136

Human response to blast-induced vibration and air-overpressure: an Indian scenario  

Microsoft Academic Search

Ground vibration ( V max) and air-overpressure\\/noise ( p) are some of the negative effects of blasting. The associated human annoyance and complaints are expected to show an increasing trend in the future as there is no economically viable alternative to blasting in mines in India. A study of the human response to blasting in four mining localities across India

A. K. Raina; A. Haldar; A. K. Chakraborty; P. B. Choudhury; M. Ramulu; C. Bandyopadhyay

2004-01-01

137

Comparison of Subjective Responses to Vibration and Shock with Standard Analysis Methods and Absorbed Power  

NASA Astrophysics Data System (ADS)

Evaluation of human exposure whole-body vibration (WBV) and shock can be carried out in a variety of ways. The most commonly used standards for predicting discomfort from WBV are BS6841 (1987) and ISO2631-1 (1997) which offer different frequency weightings (Wband Wk) and three methods of assessment: vibration dose value (VDV), estimated VDV (eVDV) and maximum transient vibration value (MTVV). Previous studies have also used DRI and absorbed power for assessments of shock and WBV. This paper reports a laboratory study in which 24 human subjects were exposed to 15 vertical vibration stimuli comprising of random vibration, repeated shocks and combinations of random vibration and shocks at 0.5, 1.0 and 1.5 m/s2r.m.s. Subjects rated the discomfort from the vibration on a numerical scale after each exposure. Acquired acceleration signals were analyzed using VDV, r.m.s. and MTVV for unweighted, Wb, Wkand DRI weighted signals. Acceleration and force were combined to give a measure of absorbed power. Subjective responses were correlated to vibration magnitude for the 13 analysis types. VDV was the best standard method of assessment; MTVV was the worst. Wband Wkfrequency weightings showed slightly greater correlations between vibration magnitude and discomfort than DRI weighted or unweighted signals. For VDV, there were no significant differences between the correlations obtained using any frequency weighting. For assessment of all stimuli types together, absorbed power gave higher correlations with subjective discomfort than acceleration-based methods. It is concluded that the methods described in ISO2631-1 should be clarified and simplified. Due to the difficulty in measuring absorbed power in the field, methods proposed in BS6841 are recommended as the most appropriate for assessment of discomfort from continuous vibration or repeated shocks.

Mansfield, N. J.; Holmlund, P.; Lundström, R.

2000-02-01

138

[Possibility of using vibration response imaging in resuscitation and intensive care].  

PubMed

Lung monitoring and visualization in intensive care unit (ICU) patients is a difficult task. Chest X-ray and auscultation are the most commonly used methods today. The new technique vibration response imaging (VRI) based on the vibration that is generated by airflow in the lung and that is its surrogate manifestation allows visualization of lung function. This method provides clinicians with an easy-to-use, non-radiation, non-invasive acoustic-based imaging technique of visual and quantitative evaluation of the lung. VRI objective dynamic image is a clinical addition to the existing static visual modalities used in the ICU. PMID:21395149

Vinshtok, Iu L; Zelenin, G B; Gulitski?, K E

139

Effect of prior exposure to hand-transmitted vibration on cold response of digital arteries  

Microsoft Academic Search

Objectives  To investigate whether prior exposure to hand-transmitted vibration on the day of a cold provocation test affects the cold\\u000a response of digital arteries.\\u000a \\u000a \\u000a \\u000a Methods  Each of ten healthy men attended two experimental sessions in which their right hands were exposed for 60 min to either contact\\u000a force alone (5 N) or a combination of contact force (5 N) and 125-Hz vertical vibration with an

Massimo Bovenzi; Alexandra J. L. Welsh; Michael J. Griffin

2007-01-01

140

Study on Vibration Characteristics of a High-rise Building using results of Microtremor, Manpower Excitation Measurements, Earthquake Observations and Simulations of a 3D Moment-frame structure  

NASA Astrophysics Data System (ADS)

In the Tokyo metropolitan area, high-rise buildings will suffer strong ground motions in near future. In order to estimate damage of the buildings and to carry out counter measures for reducing the damage, it is necessary to know the accurate vibration characteristics of the buildings during the strong ground motions. The purpose of the paper is to investigate vibration characteristics of the Shinjuku Campus building of the 28th floors in Shinjuku, Tokyo, which is a steel structure of moment frames with143 m height. First, we constructed a 3D moment frame model and compared vibration characteristics, such as the natural periods and the corresponding mode shapes, with those obtained by microtremors measurements and manpower excitations. We obtained excellent agreements between them. Second, we compared the observed building response during earthquakes with those of the simulations; we again obtained agreements.

Hoshi, Yukio; Hisada, Yoshiaki; Yamashita, Tetsuo; Masuzawa, Yoe; Shimamura, Kenta

141

Free-Vibration Characteristics of a Large Split-Blanket Solar Array in a 1-G Field.  

National Technical Information Service (NTIS)

Two methods for studying the free vibration characteristics of a large split blanket solar array in both a 0-g and a 1-g cantilevered configuration are presented. The 0-g configuration corresponds to an in-orbit configuration of the array; the 1-g configu...

F. J. Shaker

1976-01-01

142

Theoretical relationship between vibration transmissibility and driving-point response functions of the human body  

NASA Astrophysics Data System (ADS)

The relationship between the vibration transmissibility and driving-point response functions (DPRFs) of the human body is important for understanding vibration exposures of the system and for developing valid models. This study identified their theoretical relationship and demonstrated that the sum of the DPRFs can be expressed as a linear combination of the transmissibility functions of the individual mass elements distributed throughout the system. The relationship is verified using several human vibration models. This study also clarified the requirements for reliably quantifying transmissibility values used as references for calibrating the system models. As an example application, this study used the developed theory to perform a preliminary analysis of the method for calibrating models using both vibration transmissibility and DPRFs. The results of the analysis show that the combined method can theoretically result in a unique and valid solution of the model parameters, at least for linear systems. However, the validation of the method itself does not guarantee the validation of the calibrated model, because the validation of the calibration also depends on the model structure and the reliability and appropriate representation of the reference functions. The basic theory developed in this study is also applicable to the vibration analyses of other structures.

Dong, Ren G.; Welcome, Daniel E.; McDowell, Thomas W.; Wu, John Z.

2013-11-01

143

Response of the Cardiovascular System to Vibration and Combined Stresses.  

National Technical Information Service (NTIS)

Contents: Heart Rate Responses of Humans to Sinusoidally Varying + or - 1 Gz Gravitational Stress; A new chronically instrumented animal preparation in which heart rate (via AV sequential pacing) can be computer controlled in either an open or closed-loop...

C. F. Knapp J. M. Evans D. C. Randall J. B. Charles B. S. Kelley

1983-01-01

144

Non-linear dual-axis biodynamic response to fore-and-aft whole-body vibration  

Microsoft Academic Search

Seated subjects have participated in two experiments with fore-and-aft whole-body vibration to investigate dynamic responses at the seat and footrest in the direction of vibration and in other directions. In the first experiment, 12 males were exposed to fore-and-aft random vibration (0.25–20Hz) at four magnitudes (0.125, 0.25, 0.625, and 1.25ms?2 rms) while sitting on a seat with no backrest in

N. Nawayseh; M. J. Griffin

2005-01-01

145

DEFINITION OF A RANGE OF IDEALIZED VALUES TO CHARACTERIZE SEATED BODY BIODYNAMIC RESPONSE UNDER VERTICAL VIBRATION  

Microsoft Academic Search

While a considerable quantity of data has been published on driving-point mechanical impedance, apparent mass and seat-to-head transmissibility magnitude and phase characteristics of seated subjects under vertical whole-body vibration, significant variation is known to exist between various data sets. Such variations may be partly attributed to differences associated with the methodology, experimental conditions or subject population used by various investigators

P.-É. Boileau; X. Wu; S. Rakheja

1998-01-01

146

Response characteristics of selected personnel neutron dosimeters  

SciTech Connect

Performance characteristics of selected personnel neutron dosimeters in current use at Department of Energy (DOE) facilities were determined from their evaluation of neutron dose equivalent received after irradiations with specific neutron sources at either the National Bureau of Standards (NBS) or the Pacific Northwest Laboratory (PNL). The characteristics assessed included: lower detection level, energy response, precision and accuracy. It was found that when all of the laboratories employed a common set of calibrations, the overall accuracy was approximately +-20%, which is within uncertainty expected for these dosimeters. For doses above 80 mrem, the accuracy improved to better than 10% when a common calibration was used. Individual differences found in this study may reflect differences in calibration technique rather than differences in the dose rates of actual calibration standards. Second, at dose rates above 100 mrem, the precision for the best participants was generally below +-10% which is also within expected limits for these types of dosimeters. The poorest results had a standard deviation of about +-25%. At the lowest doses, which were sometimes below the lower detection limit, the precision often approached or exceeded +-100%. Third, the lower level of detection for free field /sup 252/Cf neutrons generally ranged between 20 and 50 mrem. Fourth, the energy dependence study provided a characterization of the response of the dosimeters to neutron energies far from the calibration energy. 11 references, 22 figures, 26 tables.

McDonald, J.C.; Fix, J.J.; Hadley, R.T.; Holbrook, K.L.; Yoder, R.C.; Roberson, P.L.; Endres, G.W.R.; Nichols, L.L.; Schwartz, R.B.

1983-09-01

147

Study of closed orbit response to magnet vibrations at the SSRF storage ring  

NASA Astrophysics Data System (ADS)

This paper presents the analytical and simulation responses of the closed orbit distortion in the SSRF storage ring to random and plane wave like magnet vibrations respectively. It is shown that the use of girder is very beneficial in the view of suppressing this response function. Effect of the independently supported gradient bending magnets to the closed orbit response is given. An analytic formula is written to give a rough estimate of the closed orbit distortion due to ground motion, taking into account the closed orbit response function and girder transfer function. As an example, the result of SSRF case is given. Supported by SSRF Project

Chen, Jian-Hui; Zhao, Zhen-Tang; Dai, Zhi-Min; Liu, Gui-Min

2008-07-01

148

Observations on the time course of the electromyographic response reflexly elicited by muscle vibration in man.  

PubMed Central

Surface electromyography has been used to study the initial reflex response of various muscles to vibration, applied to their tendons, when the subject was already contracting them voluntarily. The response at the onset of vibration was of a latency appropriate for Ia monosynaptic action and was always highly phasic with an initial wave rising far above any maintained increase in electromyogram (e.m.g.) activity; its duration was typically well below 20 ms in the rectified average. Thus, there is nothing peculiar, in this respect, about flexor pollicis longus for which such behaviour has already been described, and used to draw certain wide-ranging conclusions about the stretch reflex. Theoretical considerations, developed in an Appendix, show that quite apart from the operation of any inhibitory mechanisms such a phasic response is to be expected from a population of tonically discharging motoneurones when there is a step increase in the level of their excitatory drive.

Matthews, P B

1984-01-01

149

A method for assessing the effectiveness of anti-vibration gloves using biodynamic responses of the hand arm system  

NASA Astrophysics Data System (ADS)

Anti-vibration gloves are widely used to help minimize hand arm vibration exposure. In this study, an alternative method is proposed to assess the vibration isolation effectiveness of these gloves using the biodynamic responses of the bare- and gloved-hand arm system exposed to vibration. The laboratory experiments were performed with a total of five human subjects using a typical anti-vibration air bladder glove subjected to a broad-band random vibration spectrum in conjunction with a specially designed instrumented handle. The measured data were analyzed to derive the biodynamic responses of the bare as well as gloved human hand arm system in terms of the apparent mass and the mechanical impedance. The two biodynamic responses were applied to estimate the vibration isolation effectiveness of the glove. The validity of the proposed concept was examined by comparing the estimated vibration transmissibility magnitudes of the glove with those obtained using a palm adapter method. The comparison of the results suggests that the proposed method offers a good alternative for estimating glove vibration transmissibility. The measured data and the proposed method based upon the biodynamic responses were further used to investigate the effect of the palm adapter on the vibration transmissibility of the glove. The results suggest that the presence of the palm adapter between the subject's palm and the glove may not alter the basic trends in the transmissibility response, but it would affect the transmissibility magnitudes in the middle- and high-frequency ranges. A distinct advantage of the proposed method is that it eliminates the use of an adapter in assessing the vibration isolation effectiveness of the gloves.

Dong, R. G.; Rakheja, S.; McDowell, T. W.; Welcome, D. E.; Wu, J. Z.; Warren, C.; Barkley, J.; Washington, B.; Schopper, A. W.

2005-04-01

150

The Effect of Surface Wave Propagation on Neural Responses to Vibration in Primate Glabrous Skin  

PubMed Central

Because tactile perception relies on the response of large populations of receptors distributed across the skin, we seek to characterize how a mechanical deformation of the skin at one location affects the skin at another. To this end, we introduce a novel non-contact method to characterize the surface waves produced in the skin under a variety of stimulation conditions. Specifically, we deliver vibrations to the fingertip using a vibratory actuator and measure, using a laser Doppler vibrometer, the surface waves at different distances from the locus of stimulation. First, we show that a vibration applied to the fingertip travels at least the length of the finger and that the rate at which it decays is dependent on stimulus frequency. Furthermore, the resonant frequency of the skin matches the frequency at which a subpopulation of afferents, namely Pacinian afferents, is most sensitive. We show that this skin resonance can lead to a two-fold increase in the strength of the response of a simulated afferent population. Second, the rate at which vibrations propagate across the skin is dependent on the stimulus frequency and plateaus at 7 m/s. The resulting delay in neural activation across locations does not substantially blur the temporal patterning in simulated populations of afferents for frequencies less than 200 Hz, which has important implications about how vibratory frequency is encoded in the responses of somatosensory neurons. Third, we show that, despite the dependence of decay rate and propagation speed on frequency, the waveform of a complex vibration is well preserved as it travels across the skin. Our results suggest, then, that the propagation of surface waves promotes the encoding of spectrally complex vibrations as the entire neural population is exposed to essentially the same stimulus. We also discuss the implications of our results for biomechanical models of the skin.

Manfredi, Louise R.; Baker, Andrew T.; Elias, Damian O.; Dammann, John F.; Zielinski, Mark C.; Polashock, Vicky S.; Bensmaia, Sliman J.

2012-01-01

151

Damage identification and health monitoring of structural and mechanical systems from changes in their vibration characteristics: A literature review  

Microsoft Academic Search

This report contains a review of the technical literature concerning the detection, location, and characterization of structural damage via techniques that examine changes in measured structural vibration response. The report first categorizes the methods according to required measured data and analysis technique. The analysis categories include changes in modal frequencies, changes in measured mode shapes (and their derivatives), and changes

S. W. Doebling; C. R. Farrar; M. B. Prime; D. W. Shevitz

1996-01-01

152

Static analysis of a passive vibration isolator with quasi-zero-stiffness characteristic  

NASA Astrophysics Data System (ADS)

The frequency range over which a linear passive vibration isolator is effective, is often limited by the mount stiffness required to support a static load. This can be improved upon by employing nonlinear mounts incorporating negative stiffness elements configured in such a way that the dynamic stiffness is much less than the static stiffness. Such nonlinear mounts are used widely in practice, but rigorous analysis, and hence a clear understanding of their behaviour is not readily available in the literature. In this paper, a simple system comprising a vertical spring acting in parallel with two oblique springs is studied. It is shown that there is a unique relationship between the geometry and the stiffness of the springs that yields a system with zero dynamic stiffness at the static equilibrium position. The dynamic stiffness increases monotonically with displacement either side of the equilibrium position, and this is least severe when the oblique springs are inclined at an angle between approximately 48° and 57°. Finally, it is shown that the force displacement characteristic of the system can be approximated by a cubic equation.

Carrella, A.; Brennan, M. J.; Waters, T. P.

2007-04-01

153

Characteristics of chip formation in micro V-grooving using elliptical vibration cutting  

Microsoft Academic Search

The chip and burr formation in micro V-grooving using elliptical vibration cutting (EVC) was investigated. Elliptical vibration of the cutting tool was achieved by employing two parallel piezoelectric actuators excited with two sinusoidal voltages of 90° phase difference. Changes in the shape of the chip and the cutting force, and the surface texture in micro V-grooving with EVC were investigated.

Gi Dae Kim; Byoung Gook Loh

2007-01-01

154

Mechanical and Electrical Characteristics of the Electromagnetic Relay under Vibration and Shock Environment  

Microsoft Academic Search

The electromagnetic relay, which has mechanical structure and break\\/make contacts, is affected by vibration and shock environment greatly. Contact wear and failure will be result from serious mechanical conditions. The samples used in this study were relays consisting two spring sets connected with armature component. Simulation results for a variety of vibration levels, frequencies, and shock levels are presented. Thereafter

Wanbin Ren; Huimin Liang; Yinghua Chen; Li Cui; Lizhong Wang; Yunzhi Kang

2009-01-01

155

Seated occupant interactions with seat backrest and pan, and biodynamic responses under vertical vibration  

Microsoft Academic Search

The relative interactions of the seated occupants with an inclined backrest were investigated in terms of apparent mass (APMS) responses at the two driving-points formed by the buttock–seat pan and the upper body-backrest under exposure to broad-band and road-measured vertical vibration. The measurements were performed using 24 adult subjects seated with full contact with the back support and two different

S. Rakheja; I. Stiharu; H. Zhang; P.-É. Boileau

2006-01-01

156

Effect of cross-wind on spatial vibration responses of train and track system  

Microsoft Academic Search

By taking cross-wind forces acting on trains into consideration, a dynamic analysis method of the cross-wind and high-speed\\u000a train and slab track system was proposed on the basis of the analysis theory of spatial vibration of high-speed train and\\u000a slab track system. The corresponding computer program was written by FORTRAN language. The dynamic responses of the high-speed\\u000a train and slab

Jun Xiang; Dan He; Qing-yuan Zeng

2009-01-01

157

Free vibration and dynamic response analysis by Petrov-Galerkin natural element method  

Microsoft Academic Search

In this paper, a Petrov-Galerkin natural element method (PG-NEM) based upon the natural neighbor concept is presented for\\u000a the free vibration and dynamic response analyses of twodimensional linear elastic structures. A problem domain is discretized\\u000a with a finite number of nodes and the trial basis functions are defined with the help of the Voronoi diagram. Meanwhile, the\\u000a test basis functions

Jin-Rae Cho; Hong-Woo Lee

2006-01-01

158

Wind-Induced vibration responses of prestressed double-layered spherical latticed shells  

Microsoft Academic Search

This paper focuses on the wind-induced vibration response of prestressed double-layered spherical latticed shell (PDSLS) structures\\u000a by adopting time-domain analysis method. Welch spectrum analysis method is used to make precision evaluation of power spectrum\\u000a of fluctuating wind speed time history simulated by weighted amplitude wavelet superposition (WAWS) method and linear filtering\\u000a method of auto-regression (AR) model. Results show that the

Zhen Zhou; Zhi-ming Li; Shao-ping Meng; Jing Wu

2011-01-01

159

The application of finite element analysis to investigate the vibrational response of a turbine blade under thermosonic excitation  

NASA Astrophysics Data System (ADS)

This paper presents a methodology, using a combination of experimental vibration measurements and finite element analysis (FEA), to model the vibrational energy within a turbine blade corresponding to a typical thermosonic inspection scenario. Laser vibrometry measurements were used to determine the steady-state vibration response at several locations on a blade and used to identify the prominent spectral components. These were then used to generate an excitation function for the FEA approach. After validation of the FEA model, the vibration response across the whole blade was simulated. Finally, the predicted displacement field was used to determine the vibrational energy at every point on the blade which was mapped onto a CAD representation of the blade, thereby highlighting areas on the blade that may be below the defect detection threshold.

Bolu, Gabriel; Gachagan, Anthony; Pierce, Gareth; Barden, Tim

2013-01-01

160

A longitudinal study of vibration white finger, cold response of digital arteries, and measures of daily vibration exposure  

Microsoft Academic Search

Purpose  To investigate prospectively the relation between vibration-induced vascular disorders and measures of daily exposure to hand-transmitted\\u000a vibration (HTV).\\u000a \\u000a \\u000a \\u000a Methods  Two hundred and forty-nine HTV workers and 138 control men of the same companies participated in a 3-year follow-up study.\\u000a The diagnosis of vibration induced white finger (VWF) in the HTV workers and that of Raynaud’s phenomenon in the controls\\u000a was based

Massimo Bovenzi

2010-01-01

161

Mathematical model of low-frequency electromagnetic horizontal vibration platform  

NASA Astrophysics Data System (ADS)

In this paper, the mathematical model of low frequency electromagnetic vibration platform is established on the basis of its mechanical structure and electrical structure. Its frequency response characteristics are also analyzed in detail. The correctness of the mathematical model is verified by a lot of testing data. Subsequently, nonlinear factors of the vibration platform are discussed, including magnetic field's nonlinear, moving-coil response and nonlinear output of power amplifiers, and so on. These factors lead to a lot of harmonic vibration and severe vibration waveform distortion. Some measures to decrease the magnetic field's nonlinear and the effect of moving-coil response are proposed for the low frequency electromagnetic vibration platform.

Li, Xiaolei; Fan, Shangchun

2003-09-01

162

2-D differential quadrature solution for vibration characteristics of two-dimensional functionally graded metal\\/ceramic open cylindrical shells  

Microsoft Academic Search

In this paper, Semi-analytical 3-D elasticity solutions are presented to study the vibration characteristics of two-dimensional functionally graded (2-D FGM) metal\\/ceramic open cylindrical shells under various boundary conditions. In the present formulation, the shell has a smooth variation of volume fractions of metal and ceramic in the radial and axial directions with power law functions. The study is carried out

H. Hedayati; M. Hedayati; B. Sobhani Aragh; E. Borzabadi Farahani

2012-01-01

163

Calibration Characteristics of IRAD GAGE Vibrating Wire Stressmeter at Normal and High Temperature. Volume 1.  

National Technical Information Service (NTIS)

This report describes calibration studies of the IRAD GAGE Vibrating Wire Stressmeter. The work has been performed for the University of California, Lawrence Livermore Laboratory, to understand and interpret the behavior and performance of the stressmeter...

P. K. Dutta R. W. Hatfield P. W. Runstadler

1981-01-01

164

Vibrational characteristics of cracks in two-dimensional annular networks: numerical study of spectral dimensions  

NASA Astrophysics Data System (ADS)

The spectral dimensions of vibrations of cracks in an annular geometry were computed. The numerical cracks used here were calculated using the Random Fuse Model with a given disorder in the fuse burnout thresholds. Like the Hurst exponents, and hence the fractal dimension of these fractures, which depend on the imposed disorders in the fuse's burnout threshold, the spectral dimensions are different for each case. This allows the experimental analysis of the fractal features of cracks via their vibrational emissions.

Olivi-Tran, N.

2003-01-01

165

Effects of tendon vibration on the spatiotemporal characteristics of human locomotion  

Microsoft Academic Search

The present study addressed the involvement of proprioceptive input of the muscle spindles in the spatiotemporal control of\\u000a human locomotion. Blindfolded subjects walked along a walkway while tendon vibration, a powerful stimulus of Ia afferents,\\u000a was applied to various muscles of the lower limb. The effects of tendon vibration were measured on joint kinematics and on\\u000a intralimb and interlimb coordination.

Sabine M. P. Verschueren; Stephan P. Swinnen; Kaat Desloovere; Jacques Duysens

2002-01-01

166

Characteristics of Blood Flow Resistance Under Transverse Vibration: Red Blood Cell Suspension in Dextran40  

Microsoft Academic Search

Vibration under shear flow causes the reduction of flow resistance for shear-thinning fluids. The present study investigates the effect of vibration on the flow resistance of a nonaggregating red blood cell (RBC) suspension with a newly designed pressure-scanning capillary viscometer (PSCV). The PSCV was originally designed to measure non-Newtonian viscosity continuously over a range of shear rates at a time,

Sehyun Shin; Yunhee Ku; Jang-Soo Suh; Su-Yeon Moon; Jong-Yun Jang

2003-01-01

167

Analyses of biodynamic responses of seated occupants to uncorrelated fore-aft and vertical whole-body vibration  

NASA Astrophysics Data System (ADS)

The apparent mass and seat-to-head-transmissibility response functions of the seated human body were investigated under exposures to fore-aft (x), vertical (z), and combined fore-aft and vertical (x and z) axis whole-body vibration. The coupling effects of dual-axis vibration were investigated using two different frequency response function estimators based upon the cross- and auto-spectral densities of the response and excitation signals, denoted as H1 and Hv estimators, respectively. The experiments were performed to measure the biodynamic responses to single and uncorrelated dual-axis vibration, and to study the effects of hands support, back support and vibration magnitude on the body interactions with the seatpan and the backrest, characterized in terms of apparent masses and the vibration transmitted to the head. The data were acquired with 9 subjects exposed to two different magnitudes of vibration applied along the individual x- and z-axis (0.25 and 0.4 m/s2 rms), and along both the axis (0.28 and 0.4 m/s2 rms along each axis) in the 0.5-20 Hz frequency range. The two methods resulted in identical single-axis responses but considerably different dual-axis responses. The dual-axis responses derived from the Hv estimator revealed notable effects of dual-axis vibration, as they comprised both the direct and cross-axis responses observed under single axis vibration. Such effect, termed as the coupling effect, was not evident in the dual-axis responses derived using the commonly used H1 estimator. The results also revealed significant effects of hands and back support conditions on the coupling effects and the measured responses. The back support constrained the upper body movements and thus showed relatively weaker coupling compared to that observed in the responses without the back support. The effect of hand support was also pronounced under the fore-aft vibration. The results suggest that a better understanding of the seated human body responses to uncorrelated multi-axis whole-body vibration could be developed using the power-spectral-density based Hv estimator.

Mandapuram, Santosh; Rakheja, Subhash; Marcotte, Pierre; Boileau, Paul-Émile

2011-08-01

168

Free vibration of Euler and Timoshenko nanobeams using boundary characteristic orthogonal polynomials  

NASA Astrophysics Data System (ADS)

Vibration analysis of nonlocal nanobeams based on Euler-Bernoulli and Timoshenko beam theories is considered. Nonlocal nanobeams are important in the bending, buckling and vibration analyses of beam-like elements in microelectromechanical or nanoelectromechanical devices. Expressions for free vibration of Euler-Bernoulli and Timoshenko nanobeams are established within the framework of Eringen's nonlocal elasticity theory. The problem has been solved previously using finite element method, Chebyshev polynomials in Rayleigh-Ritz method and using other numerical methods. In this study, numerical results for free vibration of nanobeams have been presented using simple polynomials and orthonormal polynomials in the Rayleigh-Ritz method. The advantage of the method is that one can easily handle the specified boundary conditions at the edges. To validate the present analysis, a comparison study is carried out with the results of the existing literature. The proposed method is also validated by convergence studies. Frequency parameters are found for different scaling effect parameters and boundary conditions. The study highlights that small scale effects considerably influence the free vibration of nanobeams. Nonlocal frequency parameters of nanobeams are smaller when compared to the corresponding local ones. Deflection shapes of nonlocal clamped Euler-Bernoulli nanobeams are also incorporated for different scaling effect parameters, which are affected by the small scale effect. Obtained numerical solutions provide a better representation of the vibration behavior of short and stubby micro/nanobeams where the effects of small scale, transverse shear deformation and rotary inertia are significant.

Behera, Laxmi; Chakraverty, S.

2013-02-01

169

Nonlinear dual-axis biodynamic response of the semi-supine human body during vertical whole-body vibration  

NASA Astrophysics Data System (ADS)

Nonlinear biodynamic responses are evident in many studies of the apparent masses of sitting and standing subjects in static postures that require muscle activity for postural control. In the present study, 12 male subjects adopted a relaxed semi-supine posture assumed to involve less muscle activity than during static sitting and standing. The supine subjects were exposed to two types of vertical vibration (in the x-axis of the semi-supine body): (i) continuous random vibration (0.25 20 Hz) at five magnitudes (0.125, 0.25, 0.5, 0.75, and 1.0 m s-2 rms); (ii) intermittent random vibration (0.25 20 Hz) alternately at 0.25 and 1.0 m s-2 rms. With continuous random vibration, the dominant primary resonance frequency in the median normalised apparent mass decreased from 10.35 to 7.32 Hz as the vibration magnitude increased from 0.125 to 1.0 m s-2 rms. This nonlinear response was apparent in both the vertical (x-axis) apparent mass and in the horizontal (z-axis) cross-axis apparent mass. As the vibration magnitude increased from 0.25 to 1.0 m s-2 rms, the median resonance frequency of the apparent mass with intermittent random vibration decreased from 9.28 to 8.06 Hz whereas, over the same range of magnitudes with continuous random vibration, the resonance frequency decreased from 9.62 to 7.81 Hz. The median change in the resonance frequency (between 0.25 and 1.0 m s-2 rms) was 1.37 Hz with the intermittent random vibration and 1.71 with the continuous random vibration. With the intermittent vibration, the resonance frequency was higher at the high magnitude and lower at the low magnitude than with continuous vibration of the same magnitudes. The response was typical of thixotropy that may be a primary cause of the nonlinear biodynamic responses to whole-body vibration.

Huang, Ya; Griffin, Michael J.

2008-04-01

170

Characterization of the tendon vibration reflex response in hemi-spastic stroke individuals.  

PubMed

The objective of our study was to assess the role of persistent inward currents, or PICs, on the excitability of motoneurons innervating spastic muscle in hemi-spastic stroke individuals. This was accomplished by examining the effects of tonic vibration applied to the tendon of the biceps brachii muscle. The elicited TVR (tonic vibration reflex) provides a useful way to assess the degree of excitability of spinal neurons in spastic syndromes, and it has additional features that may signify the presence of PICs in spastic motoneurons. We applied sinusoidal stretches of varied duration to the biceps tendon of two hemi-spastic stroke individuals and one neurologically intact individual. We recorded the resulting TVR response from electromyographic(EMG) signals obtained from the biceps as well as force recorded at the wrist. The results of our preliminary study show that the initial rise of the TVR force response as well as the force magnitude are generally greater in spastic muscle, perhaps a marker of motoneuron excitability. Additionally, a shorter vibration duration was sufficient to evoke a response on the spastic side of our tested stroke subjects. However, the key marker of PICs--the decay of the force response as well as sustained after-discharge did not exhibit clear differences. Our present data suggests that motoneurons innervating spastic muscle are more readily activated, and thus exhibit increased excitability, which could possibly be a function of greater depolarization, without a change in PIC magnitude. Our data does not rule out the possibility of subthreshold activation of the PIC resulting in enhanced motoneuron depolarization. PMID:22254740

Suresh, Nina L; Wang, Inga; Heckman, C J; Rymer, W Zev

2011-01-01

171

Nonlinear dual-axis biodynamic response of the semi-supine human body during longitudinal horizontal whole-body vibration  

NASA Astrophysics Data System (ADS)

The resonance frequencies in frequency response functions of the human body (e.g. apparent mass and transmissibility) decrease with increasing vibration magnitude. This nonlinear biodynamic response is found with various sitting and standing postures requiring postural control. The present study measured the apparent mass of the body in a relaxed semi-supine posture with two types of longitudinal horizontal vibration (in the z-axis of the semi-supine body): (i) continuous random excitation (0.25 20 Hz) at five magnitudes (0.125, 0.25, 0.5, 0.75 and 1.0 ms-2 rms); (ii) intermittent random excitation (0.25 20 Hz) alternately at 0.25 and 1.0 ms-2 rms. With continuous random vibration, the dominant primary resonance frequency in the median normalised apparent mass decreased from 3.7 to 2.4 Hz as the vibration magnitude increased from 0.125 to 1.0 ms-2 rms. A nonlinear response was apparent in both the horizontal (z-axis) apparent mass and the vertical (x-axis) cross-axis apparent mass. With intermittent random vibration, as the vibration magnitude increased from 0.25 to 1.0 ms-2 rms, the median resonance frequency of the apparent mass decreased from 3.2 to 2.5 Hz whereas, with continuous random vibration over the same range of magnitudes, the resonance frequency decreased from 3.4 to 2.4 Hz. The median change in the resonance frequency (between 0.25 and 1.0 ms-2 rms) was 0.6 Hz with the intermittent random vibration and 0.9 Hz with the continuous random vibration. With intermittent vibration, the resonance frequency was higher at the high magnitude and lower at the low magnitude than with continuous vibration at the same magnitudes. The responses were consistent with passive thixotropy being a primary cause of nonlinear biodynamic responses to whole-body vibration, although reflex activity of the muscles may also have an influence.

Huang, Ya; Griffin, Michael J.

2008-04-01

172

Nonlinear subjective and biodynamic responses to continuous and transient whole-body vibration in the vertical direction  

NASA Astrophysics Data System (ADS)

The effect of the magnitude of continuous and transient whole-body vibration in the vertical direction on both subjective and biodynamic responses of human subjects has been investigated experimentally. Additionally, the relation between the subjective responses and the dynamic responses has also been studied. Twelve subjects were exposed to sinusoidal continuous vibrations at five frequencies (3.15 8.0 Hz) and at three magnitudes (0.5 2.0 m s-2 rms). They were also exposed to transient vibrations that were modulated one-and-half cycle sinusoidal waveforms at the same frequencies as the continuous vibrations and at three magnitudes corresponding to the magnitudes used for the continuous vibrations. Discomfort was measured by the method of magnitude estimation with reference stimuli having frequency components in the middle of the frequency range used in this study. The driving-point dynamic responses (the ratio between the force and the motion, i.e., acceleration and velocity, at the driving point) were also measured and divided by the responses to the reference stimuli used in the measurement of discomfort so as to allow the comparison of the dynamic responses with the discomfort responses. Both the discomfort estimates and the normalised driving-point dynamic responses were influenced by the stimuli magnitudes, especially with the continuous vibration. At 3.15 and 4.0 Hz, the discomfort estimates and the normalised mechanical impedance and apparent mass increased significantly with increases in vibration magnitude from 0.5 2.0 m s-2 rms. Magnitude estimates for discomfort were correlated with the normalised mechanical impedance and apparent mass in the frequency range investigated. For the transient vibrations, the discomfort estimates and the driving-point dynamic responses were interpreted as responses in frequency bands around the fundamental frequency of the input motion. The results indicate similar nonlinearities in discomfort and driving-point dynamic responses associated with the principal body response within the range 3.15 8 Hz. The nonlinearity in discomfort at these frequencies may be partially caused by the nonlinear dynamic response of the body and is sufficient to require consideration in methods of predicting discomfort caused by vertical whole-body vibration.

Matsumoto, Yasunao; Griffin, Michael J.

2005-11-01

173

Tendon vibration attenuates superficial venous vessel response of the resting limb during static arm exercise  

PubMed Central

Background The superficial vein of the resting limb constricts sympathetically during exercise. Central command is the one of the neural mechanisms that controls the cardiovascular response to exercise. However, it is not clear whether central command contributes to venous vessel response during exercise. Tendon vibration during static elbow flexion causes primary muscle spindle afferents, such that a lower central command is required to achieve a given force without altering muscle force. The purpose of this study was therefore to investigate whether a reduction in central command during static exercise with tendon vibration influences the superficial venous vessel response in the resting limb. Methods Eleven subjects performed static elbow flexion at 35% of maximal voluntary contraction with (EX + VIB) and without (EX) vibration of the biceps brachii tendon. The heart rate, mean arterial pressure, and rating of perceived exertion (RPE) in overall and exercising muscle were measured. The cross-sectional area (CSAvein) and blood velocity of the basilic vein in the resting upper arm were assessed by ultrasound, and blood flow (BFvein) was calculated using both variables. Results Muscle tension during exercise was similar between EX and EX + VIB. However, RPEs at EX + VIB were lower than those at EX (P <0.05). Increases in heart rate and mean arterial pressure during exercise at EX + VIB were also lower than those at EX (P <0.05). CSAvein in the resting limb at EX decreased during exercise from baseline (P <0.05), but CSAvein at EX + VIB did not change during exercise. CSAvein during exercise at EX was smaller than that at EX + VIB (P <0.05). However, BFvein did not change during the protocol under either condition. The decreases in circulatory response and RPEs during EX + VIB, despite identical muscle tension, showed that activation of central command was less during EX + VIB than during EX. Abolishment of the decrease in CSAvein during exercise at EX + VIB may thus have been caused by a lower level of central command at EX + VIB rather than EX. Conclusion Diminished central command induced by tendon vibration may attenuate the superficial venous vessel response of the resting limb during sustained static arm exercise.

2012-01-01

174

A Method of Analyzing Fatigue Cracks in Cast Iron by Measuring Vibration Characteristics Caused by Impact Striking  

NASA Astrophysics Data System (ADS)

This paper describes a technique for evaluating fatigue cracks in cast iron by analyzing vibration caused by hammer striking. The relationship between the vibration characteristics and cracking damage is quantitatively investigated for gray cast iron by using bending load tests and slitting. It is found that the resonant frequency decreases and the attenuation constant increases as cracks extend. The stage of crack extension can therefore be quantified by determining the typical relation between the attenuation constant and resonant frequency. We theoretically investigate the speed of crack growth and the destruction process of cast iron by determining the relationship between the reduction of resonant frequency caused by cracks to the stress intensity factor and stress cycles in the fatigue model. Based on the experimental results, we have devised a manhole cover diagnosis technique and we have developed a portable tester that can evaluate cracking damage of covers in the field.

Honjoh, Katsuhiko; Masuda, Jun-ichi

1995-03-01

175

Myoelectric Response of Back Muscles to Vertical Random Whole-Body Vibration with Different Magnitudes at Different Postures  

NASA Astrophysics Data System (ADS)

Back muscle forces contribute essentially to the whole-body vibration-induced spinal load. The electromyogram (EMG) can help to estimate these forces during whole-body vibration (WBV). Thirty-eight subjects were exposed to identical random low-frequency WBV (0.7, 1.0 and 1.4 m/s-2 r.m.s. weighted acceleration) at a relaxed, erect and bent forward postures. The acceleration of the seat and the force between the seat and the buttocks were measured. Six EMGs were derived from the right side of the m. trapezius pars descendens, m. ileocostalis lumborum pars thoracis, m. ileocostalis lumborum pars lumborum; m. longissimus thoracis pars thoracis, m. longissimus thoracis pars lumborum, and lumbar multifidus muscle. All data were filtered for anti-aliasing and sampled with 1000 Hz. Artefacts caused by the ECG in the EMG were identified and eliminated in the time domain using wavelets. The individually rectified and normalized EMGs were averaged across subjects. The EMGs without WBV exhibited characteristic patterns for the three postures examined. The coherence and transfer functions indicated characteristic myoelectric responses to random WBV with several effects of posture and WBV magnitude. A comprehensive set of transfer functions from the seat acceleration or the mean normalized input force to the mean processed EMG was presented. The results can be used for the development of more sophisticated models with a separate control of various back muscle groups. However, the EMG-force relationship under dynamic conditions needs to be examined in more detail before the results can be implemented. Since different reflex mechanisms depending on the frequency of WBV are linked with different types of active muscle fibres, various time delays between the EMG and muscle force may be necessary. . All rights reserved.

Blüthner, R.; Seidel, H.; Hinz, B.

2002-05-01

176

Characteristics of atomic vibrational motion in a one-component defective crystal  

NASA Astrophysics Data System (ADS)

Vibrations of atoms in a defective argon crystal are considered. Frequencies are calculated in the harmonic approximation and Mie and Einstein approximations. The vibrations are calculated for a set of local clusters differing in the position of a vacancy at different distances from a selected atom. Probabilities for these clusters are calculated within a quasichemical approximation of the lattice gas model. It is shown that when combined contributions from lateral interactions and vibrational motions are allowed for in the free crystal energy, there is an increase in the lattice constant upon a rise in temperature in all approximations. It is found that the frequencies calculated using the Mie model become closer to the frequency distribution in the harmonic approximation as the degree of crystal defectiveness increases.

Tovbin, Yu. K.; Titov, S. V.

2013-10-01

177

Energy-dependent characteristics of collisinal vibration-energy exchange in vapors of polyatomic molcules  

SciTech Connect

CO{sub 2} laser-induced delayed fluorescence was used to study the collisional vibration-energy exchange between the polyatomic molecules in gases. The efficiency of collisional exchange, the mean amount of energy transfer in one collision, as well as their correlation with the vibration energy and with the size of excited molecule were determined for diacetyl, acetophenone, benzophenone, and anthraquinone molecules form the experimentally observed pressure dependences of the decay rates and fluorescence intensities. It was shown that the mean amount of energy transfer per collision decreases with the molecular size and increases as E{sup m}, with m>2, with increasing the vibration energy. 25 refs., 4 figs., 1 tab.

Zalesskaya, G.A.; Yakovlev, D.L. [Institute of Molecular and Atomic Physics, Minsk (Belarus)

1995-02-01

178

Dynamic model for free vibration and response analysis of rotating beams  

NASA Astrophysics Data System (ADS)

A new modeling method for the vibration analysis of a rotating cantilever beam is proposed and compared to the other modeling methods. Applying the Hamilton principle, the equations for the axial, chordwise and flapwise motions are derived. During the derivation of these equations, the nonlinear von Karman strain and the corresponding linear stress are used to consider the stiffening effect due to rotation. The derived equations of motion obtained from the proposed method are analytically and numerically compared to equations from the previous modeling methods. Computations of the natural frequencies and time responses show that the described equations of motion are more reliable than the equations of the other modeling methods.

Kim, Hyungrae; Hee Yoo, Hong; Chung, Jintai

2013-10-01

179

Seated occupant interactions with seat backrest and pan, and biodynamic responses under vertical vibration  

NASA Astrophysics Data System (ADS)

The relative interactions of the seated occupants with an inclined backrest were investigated in terms of apparent mass (APMS) responses at the two driving-points formed by the buttock seat pan and the upper body-backrest under exposure to broad-band and road-measured vertical vibration. The measurements were performed using 24 adult subjects seated with full contact with the back support and two different positions of the hands (in lap and on steering wheel), while exposed to three different levels of broad band (0.25, 0.5 and 1.0 m/s2 rms acceleration) vibration in the 0.5 40 Hz frequency range, and a track-measured vibration spectrum (1.07 m/s2 rms acceleration). The forces developed on the seat pan and the backrest in directions normal to the supporting surfaces were measured to derive the APMS responses at both the driving-points. The results showed significant interactions of the upper body with the back support in a direction normal to the backrest, even though the vibration is applied along the vertical axis. At low frequencies, the backrest APMS magnitude was smaller than that measured at the seat pan, but it either exceeded or approached that of the seat pan APMS in the vicinity of the primary resonant frequencies. The results also suggested considerable effect of the hands position on the APMS magnitudes measured at both the driving-points. The effects of variations in the excitation type and magnitude, considered in this study, were observed to be small compared to those caused by the hands position and individual body masses. Owing to the strong effects of the body mass on the measured APMS responses at both driving-points, a total of 8 target data sets were identified corresponding to four mass groups (<60, 60.6 70, 70.5 80 and >80 kg) and two hands positions for formulating mechanical equivalent models. The model parameters identified for the target functions suggested that the models mass, stiffness and damping parameters increase with increasing body mass. The observed variations in the identified parameters could be applied for predicting the APMS responses reflected on the pan as well as backrest of the human occupants with specific body mass.

Rakheja, S.; Stiharu, I.; Zhang, H.; Boileau, P.-É.

2006-12-01

180

Vibration Characteristics of Acoustically Levitated Object with Rigid and Elastic Reflectors  

NASA Astrophysics Data System (ADS)

Levitation stability is a crucial factor that influences acoustic levitation capability. We present two sample-including models for a single-axis acoustic levitator with either a rigid or elastic reflector. Numerical analysis shows that, with the rigid reflector, both the decay time from initial disturbance and the vibration amplitude increase with sample density, which is unfavorable for levitation stability. However, with the elastic reflector, the decay time and the vibration amplitude are greatly reduced by choosing appropriate parameters of the reflector. Experimental results agree well with theoretical predictions, indicating that levitation stability can be remarkably enhanced by replacing the rigid reflector with an elastic reflector.

Hong, Zhen-Yu; Xie, Wen-Jun; Wei, Bing-Bo

2010-01-01

181

The Response of Vocal Fold Fibroblasts and Mesenchymal Stromal Cells to Vibration  

PubMed Central

Illumination of cellular changes caused by mechanical forces present within the laryngeal microenvironment may well guide strategies for tissue engineering the vocal fold lamina propria. The purpose of this study was to compare the response of human vocal fold fibroblasts (hVFF) and bone marrow mesenchymal stem cells (BM-MSC) to vibratory stimulus. In order to study these effects, a bioreactor capable of vibrating two cell seeded substrates was developed. The cell seeded substrates contact each other as a result of the sinusoidal frequency, producing a motion similar to the movement of true vocal folds. Utilizing this bioreactor, hVFF and BM-MSC were subjected to 200 Hz vibration and 20% strain for 8 hours. Immunohistochemistry (Ki-67 and TUNEL) was performed to examine cell proliferation and apoptosis respectively, while semi-quantitative RT-PCR was used to assess extracellular matrix related gene expression. HVFF significantly proliferated (p?=?0.011) when subjected to 200 Hz vibration and 20% strain, while BM-MSC did not (p?=?1.0). A statistically significant increase in apoptosis of BM-MSC (p?=?0.0402) was observed under the experimental conditions; however high cell viability (96%) was maintained. HVFF did not have significantly altered apoptosis (p?=?0.7849) when subjected to vibration and strain. Semi-quantitative RT-PCR results show no significant differences in expression levels of collagen I (BM-MSC p?=?0.1951, hVFF p?=?v0.3629), fibronectin (BM-MSC p?=?0.1951, hVFF p?=?0.2513), and TGF-?1 (BM-MSC p?=?0.2534, hVFF p?=?0.6029) between vibratory and static conditions in either cell type. Finally, smooth muscle actin mRNA was not present in either vibrated or static samples, indicating that no myofibroblast differentiation occurred for either cell type. Together, these results demonstrate that BM-MSC may be a suitable alternative to hVFF for vocal fold tissue engineering. Further investigation into a larger number of gene markers, protein levels, increased number of donors and vibratory conditions are warranted.

Gaston, Joel; Quinchia Rios, Beatriz; Bartlett, Rebecca; Berchtold, Craig; Thibeault, Susan L.

2012-01-01

182

Static analysis of a passive vibration isolator with quasi-zero-stiffness characteristic  

Microsoft Academic Search

The frequency range over which a linear passive vibration isolator is effective, is often limited by the mount stiffness required to support a static load. This can be improved upon by employing nonlinear mounts incorporating negative stiffness elements configured in such a way that the dynamic stiffness is much less than the static stiffness. Such nonlinear mounts are used widely

A. Carrella; M. J. Brennan; T. P. Waters

2007-01-01

183

Vibration characteristics of a circular plate with a concentric reinforcing ring  

Microsoft Academic Search

The problem of the axisymmetric vibration of a uniform circular plate reinforced by a concentric ring of arbitrary cross-section is studied. A general solution to the differential equation is taken and required to satisfy exactly the two boundary conditions at the edge 0f the plate and the four conditions of continuity at the junction of the plate and the reinforcing

C. L. Kirk; A. W. Leissa

1967-01-01

184

A study of the temperature characteristics of vibration mode axes for vibratory cylinder gyroscopes.  

PubMed

The zero bias stability, which is an important performance parameter for vibratory cylinder gyroscopes, is high sensitive to temperature change. It is considered that the varying temperature makes the vibration mode axes unstable, which has significant influence on the zero bias stability. This paper will investigate this problem in detail. First, the relationships between the angular positions of vibration mode axes and the zero bias are analyzed. Secondly, the thermal-modal model of the cylinder resonator with several defects such as mass imbalance, frequency split (FS), and geometry errors are developed by ANSYS. Simulation results show that with the increase of temperature, angular positions of the vibration mode axes obviously change, which leads to a dramatic zero bias drift. Finally, several major influence factors on the angular position stability of vibration mode axes, including frequency split, geometry errors, thermal elastic modulus coefficient (TEMC) and thermal expansion coefficient (TEC) are analyzed in detail. Simulation results in this paper will be helpful for deep understanding of the drift principle of zero bias induced by temperature for vibratory cylinder gyroscopes and also be helpful for further temperature compensation or control. PMID:22164038

Wu, Yulie; Xi, Xiang; Tao, Yi; Wu, Xiaomei; Wu, Xuezhong

2011-08-04

185

Dispersive Characteristics Analysis and Vibration Isolation Simulation of Floating Slab Track System  

Microsoft Academic Search

A double-beam model on rigid foundation subject to a harmonic moving load is employed in this paper to assess vibration isolation performance of floating slab system with various parameters. The track is assumed to act as infinitely long double Euler-Bernoulli beam on elastic foundation. By means of moving coordinate and Fourier transformation method, the differential equations of floating slab track

Jun Yuan; Zhao-bo Meng; Min-zhe Wu; Lin Song

2008-01-01

186

Vibrational power flow characteristics of circular plate structures with peripheral surface crack  

Microsoft Academic Search

In the view of structure-borne sound, the vibrational power flow of circular plates with peripheral surface crack is investigated. The peripheral surface crack is modelled as a joint of a local spring. The local stiffness of the rotational spring is deduced by using fracture mechanics and strain energy arguments. At high frequencies, the motion of bending wave and the input

T. Y Li; J. X. Liu; T. Zhang

2004-01-01

187

Characteristics of an active feedback system for the control of plate vibrations  

Microsoft Academic Search

In the interests of improving airborne insulation of panels and of controlling room reverberation, a technique is studied for establishing control of the transverse vibrations of a thin plate by the application of active energy feedback. A localized point control force is derived from the sensed motion of some point on the plate surface. The superposition principle is applied in

L. A. Walker; P. P. Yaneske

1976-01-01

188

Measurement of vibration characteristics of a magnet prototype girder for ALBA  

Microsoft Academic Search

The 3 GeV third generation synchrotron light source ALBA is under construction near Barcelona. The machine is foreseen to operate with a low emittance (less than 5 nm·rad) and small size (under 150 µm in horizontal and 8 µm in vertical) electron beam. Uncorrelated mechanical vibrations of the magnets, amplified by the lattice transfer function, could degrade the beam stability

Ramila Amirikas; Alessandro Bertolini; Wilhelm Bialowons

189

A Study of the Temperature Characteristics of Vibration Mode Axes for Vibratory Cylinder Gyroscopes  

PubMed Central

The zero bias stability, which is an important performance parameter for vibratory cylinder gyroscopes, is high sensitive to temperature change. It is considered that the varying temperature makes the vibration mode axes unstable, which has significant influence on the zero bias stability. This paper will investigate this problem in detail. First, the relationships between the angular positions of vibration mode axes and the zero bias are analyzed. Secondly, the thermal-modal model of the cylinder resonator with several defects such as mass imbalance, frequency split (FS), and geometry errors are developed by ANSYS. Simulation results show that with the increase of temperature, angular positions of the vibration mode axes obviously change, which leads to a dramatic zero bias drift. Finally, several major influence factors on the angular position stability of vibration mode axes, including frequency split, geometry errors, thermal elastic modulus coefficient (TEMC) and thermal expansion coefficient (TEC) are analyzed in detail. Simulation results in this paper will be helpful for deep understanding of the drift principle of zero bias induced by temperature for vibratory cylinder gyroscopes and also be helpful for further temperature compensation or control.

Wu, Yulie; Xi, Xiang; Tao, Yi; Wu, Xiaomei; Wu, Xuezhong

2011-01-01

190

Lateral stiffness and vibration characteristics of composite plated RC shear walls with variable fibres spacing  

Microsoft Academic Search

In this paper, a finite element model for static and free vibration analysis of reinforced concrete (RC) shear walls structures strengthened with thin composite plates having variable fibres spacing is presented. An efficient analysis method that can be used regardless to the sizes and location of the bonded plates is proposed in this study. In the numerical formulation, the adherents

S. A. Meftah; R. Yeghnem; A. Tounsi; E. A. Adda Bedia

2008-01-01

191

Semi-analytical study of free vibration characteristics of shear deformable filament wound anisotropic shells of revolution  

NASA Astrophysics Data System (ADS)

Free vibration characteristics of filament wound anisotropic shells of revolution are investigated by using multisegment numerical integration technique in combination with a modified frequency trial method. The applicability of multisegment numerical integration technique is extended to the solution of free vibration problem of anisotropic composite shells of revolution through the use of finite exponential Fourier transform of the fundamental shell equations. The governing shell equations comprise the full anisotropic form of the constitutive relations, including first-order transverse shear deformation, and all components of translatory and rotary inertia. The variation of the stiffness coefficients along the axis of the shell is also incorporated into the solution method. Filaments are assumed to be placed along the geodesic fiber path on the shell of revolution resulting in the variation of the stiffness coefficients along the axis of the composite shell of revolution with general meridional curvature. Sample solutions have been performed on the effect of the variation of the stiffness coefficients on the free vibration behavior of filament wound truncated conical and spherical shells of revolution.

Kayran, Altan; Yavuzbalkan, Erdem

2009-01-01

192

Stationary transducer response to planetary-gear vibration excitation II: Effects of torque modulations  

NASA Astrophysics Data System (ADS)

The frequency spectra of the outputs of transducers fixed to the ring gears of planetary-gear systems contain useful information pertaining to the health of such systems. The effects on such frequency spectra arising from non-uniform loading carried by the M planets in such systems was derived and illustrated in “Stationary transducer response to planetary-gear vibration excitation with non-uniform planet loading,” by Mark and Hines [W.D. Mark, J.A. Hines, Stationary transducer response to planetary-gear vibration excitation with non-uniform planet loading, Mechanical Systems and Signal Processing 23 (2009) 1366-1381]. The present paper extends this earlier analysis by predicting the added effects on such frequency spectra caused by planet-carrier torque modulations. It is shown that such torque modulations produce “sideband” harmonics on the harmonic contributions arising from uniform loading carried by the planets, and additional “sideband” harmonics on the harmonic contributions arising from the lack of uniformity of loading carried by the planets. An example is discussed for torque modulations with a period of 1/B times the planet-carrier rotation period. This example illustrates the effects of torque modulations on the transducer output spectra of a UH-60A rotorcraft with a B=4 blade rotor and M=5 planets.

Mark, W. D.

2009-10-01

193

Method for Vibration Response Simulation and Sensor Placement Optimization of a Machine Tool Spindle System with a Bearing Defect  

PubMed Central

Bearing defects are one of the most important mechanical sources for vibration and noise generation in machine tool spindles. In this study, an integrated finite element (FE) model is proposed to predict the vibration responses of a spindle bearing system with localized bearing defects and then the sensor placement for better detection of bearing faults is optimized. A nonlinear bearing model is developed based on Jones' bearing theory, while the drawbar, shaft and housing are modeled as Timoshenko's beam. The bearing model is then integrated into the FE model of drawbar/shaft/housing by assembling equations of motion. The Newmark time integration method is used to solve the vibration responses numerically. The FE model of the spindle-bearing system was verified by conducting dynamic tests. Then, the localized bearing defects were modeled and vibration responses generated by the outer ring defect were simulated as an illustration. The optimization scheme of the sensor placement was carried out on the test spindle. The results proved that, the optimal sensor placement depends on the vibration modes under different boundary conditions and the transfer path between the excitation and the response.

Cao, Hongrui; Niu, Linkai; He, Zhengjia

2012-01-01

194

Vibration Characteristics of Functionally Graded Plates with Non-Ideal Boundary Conditions  

Microsoft Academic Search

An analytical investigation is carried out to determine the vibration behavior of functionally graded plates with non-ideal boundary conditions. The plate has three edges simply supported while the other edge has a small non-zero deflection and moment. The effective material properties are estimated by the Mori-Tanaka scheme. The classical plate theory is employed to obtain the frequency equation. The proposed

M. M. Najafizadeh; J. Mohammadi; P. Khazaeinejad

2012-01-01

195

Human vibration characteristic and experiment research on man-machine system in dynamic environment  

Microsoft Academic Search

According to the design and analysis needs of man-machine interface in mechanical system in dynamic environment, a 4-DOF vertical vibration model of the human upper body of man-machine system is set up based on multi-body dynamics. The kinetic parameters of this model are obtained by the method of parameter identification and optimization theory (equivalent mass, equivalent stiffness and equivalent damping).

Xu Linan; E. Zhang; Liu Mingli; Shao Xiaochun; Zhang Fan

2008-01-01

196

The effect of van der Waals interaction modeling on the vibration characteristics of multiwalled carbon nanotubes  

Microsoft Academic Search

An elastic multiple shell model is used for the vibration analysis of multiwalled carbon nanotubes (MWCNTs). The van der Waals (vdW) interaction between any two layers of the MWCNT is modeled as the radius-dependent function. Based on the simplified Donnell shell equations, explicit formulas are obtained for the radial-dominated natural frequencies and mode shapes of double- and triple-walled carbon nanotubes.

X. Q. He; M. Eisenberger; K. M. Liew

2006-01-01

197

Verification test and evaluation of vibration characteristics for the ASTER cryocoolers  

NASA Astrophysics Data System (ADS)

The advanced spaceborne thermal emission and reflection radiometer (ASTER) is an instrument which was selected by NASA to fly on the EOS-AM1 platform in 1998. Two cryocoolers are required to cool infrared detectors for the short-wave infrared radiometer (SWIR) and thermal infrared radiometer (TIR). The mission lifetime of the EOS-AM1 platform is expected to be 5 years, and accordingly, an operation lifetime more than 5 years is required for ASTER cryocoolers. The goals in the development of the ASTER cryocoolers are realization of a operation lifetime of over 50,000 hours and mechanical vibration forces below 0.1 N in the frequency range from 40 Hz to 135 Hz in the driection of all three axes. A split- Stirling cycle cryocoolers with clearance seals and linear motors is employed for this purpose. The compressor design adopts a piston driving mechanism which has a twin-opposed piston configuration in one compression space. The mechanical vibration caused by a displacer in the expander unit is reduced by an active balancer. Cryocoolers for SWIR and TIR have cooling capacity of 1.2 W at 70 K with power consumption lower than 55 W without control electronics. Several engineering models (EM) have been fabricated and are presently undergoing performance and life tests. Results of cryocooler verification tests and effects of jitter of mechanical vibration on the ASTER instrument are described.

Kawada, Masakuni; Fujisada, Hiroyuki; Kobayashi, Minoru; Akao, Hiroshi; Nishihara, Osamu; Nishimoto, Atsushi

1995-09-01

198

Fission fragment response characteristics of thin film plastic scintillators  

Microsoft Academic Search

Results are presented of measurements of the energy loss response of thin film plastic scintillators using fission fragments for a range of film thicknesses from 0.8 to 6 mum. Previously reported anomalous response behaviour of the thin film plastic scintillators of 4-5 mum thickness was not observed. The improved understanding of the light response characteristics of TFPS makes possible their

C. B. Franklyn

1988-01-01

199

Effect of supplemental tryptophan, vitamin E, and a herbal product on responses by pigs to vibration.  

PubMed

Economic losses related to increased stress during the transport of pigs are well documented. The effects of supplementing of tryptophan (Trp), vitamin E, or a herbal product via feed or drinking water were investigated in terms of effects on stress response in pigs during transport simulation. The study consisted of three analogous experiments. For the testing in each experiment, the pigs (23.5+/-3.2 kg) were allocated to one of two treatments, with and without supplementation of a product. The applied doses were Trp (5 g/L drinking water for 3 d), vitamin E (additional amount of 300 mg/kg feed for 21 d, as-fed basis), and Sedafit (2.5 g/L drinking water for 2 d). Sedafit is a commercial herbal product containing Valeriana officinalis L. and Passiflora incarnata L. as active components. In each experiment of the study, at least 47 pigs were involved, which were treated in groups of 3. The day before transport simulation, a Holter device was attached to the pigs to produce an electrocardiogram during the night (rest values), as well as during vibration in the transport simulator (1.2 Hz, 1 m/s2), where the behavior of the pigs (standing-sitting-lying) was also observed. Samples of saliva (taken before, during, and after [3x] vibration) and blood (taken before and after vibration) were analyzed for cortisol and intermediate metabolites (glucose, lactate, creatine kinase, and nonesterified fatty acids), respectively. Pigs supplemented with Trp tended to spend more time lying down during the second hour of vibration (P < 0.05). Vitamin E decreased the peak heart rate (P < 0.05), ventricular ectopic beats (P < 0.01), and ST elevation (P < 0.10). The supplementation of Sedafit resulted in smaller increases of the investigated heart variables (minimum heart rate, P < 0.05; ventricular ectopic beats, P < 0.05; ST elevation, P < 0.01) during and after stress evocation compared with the control group. None of the tested products influenced the intermediate metabolites; one possible explanation for this finding may be that peak values were reached before the time of bleeding. In conclusion, Trp had a positive behavioral effect in this experiment, and vitamin E and Sedafit mediated an increase in some heart variables, suggesting sedative and antianxiety effects. PMID:15318742

Peeters, E; Driessen, B; Steegmans, R; Henot, D; Geers, R

2004-08-01

200

Directionality in the mechanical response to substrate vibration in a treehopper (Hemiptera: Membracidae: Umbonia crassicornis )  

Microsoft Academic Search

The use of substrate vibrations in communication and predator-prey interactions is widespread in arthropods. In many contexts, localization of the vibration source plays an important role. For small species on solid substrates, time and amplitude differences between receptors in different legs may be extremely small, and the mechanisms of vibration localization are unclear. Here we ask whether directional information is

Reginald B. Cocroft; Tai D. Tieu; Ronald R. Hoy; Ronald N. Miles

2000-01-01

201

Biodynamic response of the seated human body to single-axis and dual-axis vibration: effect of backrest and non-linearity.  

PubMed

The biodynamic responses to the human body give an understanding of why human responses to vibration (changes in health, comfort, and performance) vary with the frequency and direction of vibration. Studies have shown that biodynamic responses also vary with the magnitude of vibration and that the backrests of seats influence the transmission of vibration to the seated human body. There has been little study of the nonlinearity in the biodynamic responses of the body to dual-axis excitation and no study of the influence of backrests during dual-axis excitation. This study investigated the apparent mass and cross-axis apparent mass of the human body exposed to random vibration (0.2 to 20 Hz) in all 15 possible combinations of four magnitudes (0, 0.25, 0.5 and 1.0 ms(-2) r.m.s.) of fore-and-aft vibration and the same four magnitudes of vertical vibration. Nonlinearity was evident, with the body softening with increasing magnitude of vibration when using a fixed magnitude of vibration in one direction and varying the magnitude of vibration in the other direction. The fore-and-aft apparent mass on the seat was greater without a backrest at the lower frequencies but greater with a backrest at the higher frequencies. The vertical apparent mass on the seat was decreased by the backrest at low frequencies. Cross-axis coupling was evident, with excitation in one axis producing a response in the other axis. It is concluded that the nonlinearity of the body evident during single-axis and multi-axis vibration, and the influence of backrests, should be taken into account when determining frequency weightings for predicting human responses to vibration and when optimising the dynamics of seating to minimise exposure to vibration. PMID:22146145

Qiu, Yi; Griffin, Michael J

2011-12-06

202

Separating Fluid Shear Stress from Acceleration during Vibrations in Vitro: Identification of Mechanical Signals Modulating the Cellular Response  

PubMed Central

The identification of the physical mechanism(s) by which cells can sense vibrations requires the determination of the cellular mechanical environment. Here, we quantified vibration-induced fluid shear stresses in vitro and tested whether this system allows for the separation of two mechanical parameters previously proposed to drive the cellular response to vibration – fluid shear and peak accelerations. When peak accelerations of the oscillatory horizontal motions were set at 1g and 60Hz, peak fluid shear stresses acting on the cell layer reached 0.5Pa. A 3.5-fold increase in fluid viscosity increased peak fluid shear stresses 2.6-fold while doubling fluid volume in the well caused a 2-fold decrease in fluid shear. Fluid shear was positively related to peak acceleration magnitude and inversely related to vibration frequency. These data demonstrated that peak shear stress can be effectively separated from peak acceleration by controlling specific levels of vibration frequency, acceleration, and/or fluid viscosity. As an example for exploiting these relations, we tested the relevance of shear stress in promoting COX-2 expression in osteoblast like cells. Across different vibration frequencies and fluid viscosities, neither the level of generated fluid shear nor the frequency of the signal were able to consistently account for differences in the relative increase in COX-2 expression between groups, emphasizing that the eventual identification of the physical mechanism(s) requires a detailed quantification of the cellular mechanical environment.

Uzer, Gunes; Manske, Sarah L; Chan, M Ete; Chiang, Fu-Pen; Rubin, Clinton T; Frame, Mary D; Judex, Stefan

2012-01-01

203

Vibration response of double-walled carbon nanotubes subjected to an externally applied longitudinal magnetic field: A nonlocal elasticity approach  

NASA Astrophysics Data System (ADS)

The magnetic properties of carbon nanotubes and their mechanical behaviour in a magnetic field have attracted considerable attention among the scientific and engineering communities. This paper reports an analytical approach to study the effect of a longitudinal magnetic field on the transverse vibration of a magnetically sensitive double-walled carbon nanotube (DWCNT). The study is based on nonlocal elasticity theory. Equivalent analytical nonlocal double-beam theory is utilised. Governing equations for nonlocal transverse vibration of the DWCNT under a longitudinal magnetic field are derived considering the Lorentz magnetic force obtained from Maxwell's relation. Numerical results from the model show that the longitudinal magnetic field increases the natural frequencies of the DWCNT. Both synchronous and asynchronous vibration phases of the tubes are studied in detail. Synchronous vibration phases of DWCNT are more affected by nonlocal effects than asynchronous vibration phases. The effects of a longitudinal magnetic field on higher natural frequencies are also presented. Vibration response of DWCNT with outer-wall stationary and single-walled carbon nanotube under the effect of longitudinal magnetic field are also discussed in the paper.

Murmu, T.; McCarthy, M. A.; Adhikari, S.

2012-11-01

204

Parametric reduced order models for predicting the nonlinear vibration response of cracked structures with uncertainty  

NASA Astrophysics Data System (ADS)

Modeling and re-analysis techniques are proposed for predicting the dynamic response of complex structures that have suffered damage in one or more of their components. When such damages are present, the model of the healthy structure may no longer capture the system-level response or the loading from the rest of the structure on the damaged components. Hence, novel models that allow for an accurate re-analysis of the response of damaged structures are needed in important applications, including damage detection. Herein, such models are obtained by using a reduced order modeling approach based on component mode synthesis. Because the resonant response of a complex structure is often sensitive to component uncertainties (in geometric parameters such as thickness, material properties such as Young's modulus, etc.), novel parametric reduced order models (PROMs) are developed. In previous work, PROMs have been applied for handling uncertainties in a single substructure. Herein, PROMs are extended to the general case of multiple substructures with uncertain parameters or damage. Two damage cases are considered: severe structural deformation (dents), and cracks. For the first damage case, an approximate method based on static mode compensation (SMC) is used to perform fast re-analysis of the vibration response of the damaged structure. The re-analysis is performed through a range of locations and severity levels of the damage. For selected damage locations and levels, the SMC approximation is compared to full finite element analysis to demonstrate the accuracy and computational time savings for the new method. For the second damage case (cracks), the vibration problem becomes nonlinear due to the intermittent contact of the crack faces. Therefore, to estimate the resonant frequencies for a cracked structure, the bi-linear frequency approximation (BFA) is used for cracks of various lengths. Since BFA is based on linear analyses, it is fast and particularly well suited for implementation with PROMs for structural re-analysis. In contrast, most other nonlinear techniques for predicting the dynamic response are computationally intensive and cumbersome. For validating the proposed PROMs, resonant frequencies predicted using BFA and PROMs are shown to agree very well with results obtained using a much more expensive commercial finite element tool.

Hong, Sung-Kwon; Castanier, Matthew P.; Epureanu, Bogdan I.

2009-03-01

205

A hybrid analytical model for the transverse vibration response of a micro-end mill  

NASA Astrophysics Data System (ADS)

As a result of its detrimental effect on tool life and product quality, vibration analyses are crucial if the full potential of micro-milling operation is to be attained. In this paper, a hybrid analytical model (HAM) developed for estimating the transverse response of a micro-end mill is presented. The HAM is a combination of discrete and distributed structural elements. The discrete elements account for the stiffness and damping coefficients of the machining system, while the distributed elements idealize the geometrical representation of the micro-end mill with a novel model of the micro-flute. A number of slot micro-end milling operations, carefully designed with the Taguchi method of design of experiments, are carried out to examine the accuracy of the HAM. The comparison of the response profile from the experiment and the developed model shows reasonably close similarity. The influence of the helix angle is found to be far greater on the response of the micro-end mill than the other geometric variables. By making use of the root mean square of the response, it is further observed that the representation of the micro-flute of the micro-end mill with a less accurate model deteriorates the prediction of the HAM.

Mustapha, K. B.; Zhong, Z. W.

2013-01-01

206

Trends in design for the shock and vibration environment  

NASA Astrophysics Data System (ADS)

Trends in mechanical and structural design are discussed in relation to the dynamic response of structures to a vibration and shock environment. The possible consequences of vibration for material wear, fretting and fatigue, and systems malfunctions and reliability are indicated, and noise and vibrations standards for people and mechanical devices are considered, with attention given to the difficulty of the general design of structures to obtain a specified dynamic performance. Expressions for the dynamic characteristics of a structure are presented, and methods of analytical dynamic response prediction and shock and vibration testing are discussed, with attention given to conventional linear electromagnetic vibrator tests as well as torsional vibration tests. It is noted that considerable progress has been achieved in analytical and laboratory techniques for vibration analysis and modal analysis, to aid in designs in compliance with new specifications and standards.

Grootenhuis, P.

1980-06-01

207

Optical measurement of the weak non-linearity in the eardrum vibration response to auditory stimuli  

NASA Astrophysics Data System (ADS)

The mammalian hearing organ consists of the external ear (auricle and ear canal) followed by the middle ear (eardrum and ossicles) and the inner ear (cochlea). Its function is to convert the incoming sound waves and convert them into nerve pulses which are processed in the final stage by the brain. The main task of the external and middle ear is to concentrate the incoming sound waves on a smaller surface to reduce the loss that would normally occur in transmission from air to inner ear fluid. In the past it has been shown that this is a linear process, thus without serious distortions, for sound waves going up to pressures of 130 dB SPL (˜90 Pa). However, at large pressure changes up to several kPa, the middle ear movement clearly shows non-linear behaviour. Thus, it is possible that some small non-linear distortions are also present in the middle ear vibration at lower sound pressures. In this thesis a sensitive measurement set-up is presented to detect this weak non-linear behaviour. Essentially, this set-up consists of a loud-speaker which excites the middle ear, and the resulting vibration is measured with an heterodyne vibrometer. The use of specially designed acoustic excitation signals (odd random phase multisines) enables the separation of the linear and non-linear response. The application of this technique on the middle ear demonstrates that there are already non-linear distortions present in the vibration of the middle ear at a sound pressure of 93 dB SPL. This non-linear component also grows strongly with increasing sound pressure. Knowledge of this non-linear component can contribute to the improvement of modern hearing aids, which operate at higher sound pressures where the non-linearities could distort the signal considerably. It is also important to know the contribution of middle ear non-linearity to otoacoustic emissions. This are non-linearities caused by the active feedback amplifier in the inner ear, and can be detected in the external and middle ear. These signals are used for diagnostic purposes, and therefore it is important to have an estimate the non-linear middle ear contribution to these emissions.

Aerts, Johan

208

Normal-mode characteristics of chlorophyll models. Vibrational analysis of metallooctaethylchlorins and their selectively deuterated analogues  

SciTech Connect

The resonance Raman (RR) and infrared (IR) spectra of the Zn, Cu, and Ni complexes of trans-octaethylchlorin (OEC) reveal significant differences in the vibrational-mode properties of metallochlorins and metalloporphyrins. Modes with a contribution from the C{sub a}C{sub m} stretching coordinate are distinguished by their sensitivity to metal substitution and to selective d{sub 2} and d{sub 4} methine deuteration. Comparison of the resonance Raman spectrum of CuOEC with that of CuECI (ECI = etiochlorin I) identifies those modes with a contribution from C{sub b}C{sub b} and C{sub b}C{sub s} stretching and C{sub b}C{sub s} bending coordinates. The results obtained show that there is substantial mixing of C{sub a}C{sub m} and C{sub b}C{sub b} stretching character in the high-frequency modes of MOEC. The suggestion that the symmetry reduction that occurs in metallochlorins relative to metalloporphyrins produces vibrational-mode localization to specific hemispheres or quadrants of the macrocycle has been tested and confirmed by specific d{sub 2} deuteration at the methine carbons. Resonance Raman spectra of CuOEP-d{sub 2} (OEP = octaethylporphyrin) and CuOEP-d{sub 4} establish that, for a delocalized mode, methine d{sub 2} deuteration can be expected to produce half the d{sub 4} shift. For CuOEC, selective deuteration at the {alpha}{beta} and {gamma},{delta} methine positions causes different patterns of frequency shifts that indicate the extent of mode localization.

Fonda, H.N.; Oertling, W.A.; Salehi, A.; Chang, C.K.; Babcock, G.T. (Michigan State Univ., East Lansing (United States))

1990-12-19

209

An on-road shock and vibration response test series utilizing worst case and statistical analysis techniques  

SciTech Connect

Defining the maximum expected shock and vibration responses for an on-road truck transportation environment is strongly dependent on the amount of response data that can be obtained. One common test scheme consists of measuring response data over a relatively short prescribed road course and then reviewing that data to obtain the maximum response levels. The more mathematically rigorous alternative is to collect an unbiased ensemble of response data during a long road trip. This paper compares data gathered both ways during a recent on-road certification test for a tractor trailer van being designed by Sandia.

Cap, J.S. [Sandia National Labs., Albuquerque, NM (US). Mechanical and Thermal Environments Dept.

1997-11-01

210

Vibration Response Imaging: evaluation of rater agreement in healthy subjects and subjects with pneumonia  

PubMed Central

Background We evaluated pulmonologists variability in the interpretation of Vibration response imaging (VRI) obtained from healthy subjects and patients hospitalized for community acquired pneumonia. Methods The present is a prospective study conducted in a tertiary university hospital. Twenty healthy subjects and twenty three pneumonia cases were included in this study. Six pulmonologists blindly analyzed images of normal subjects and pneumonia cases and evaluated different aspects of VRI images related to the quality of data aquisition, synchronization of the progression of breath sound distribution and agreement between the maximal energy frame (MEF) of VRI (which is the maximal geographical area of lung vibrations produced at maximal inspiration) and chest radiography. For qualitative assessment of VRI images, the raters' evaluations were analyzed by degree of consistency and agreement. Results The average value for overall identical evaluations of twelve features of the VRI image evaluation, ranged from 87% to 95% per rater (94% to 97% in control cases and from 79% to 93% per rater in pneumonia cases). Inter-rater median (IQR) agreement was 91% (82-96). The level of agreement according to VRI feature evaluated was in most cases over 80%; intra-class correlation (ICC) obtained by using a model of subject/rater for the averaged features was overall 0.86 (0.92 in normal and 0.73 in pneumonia cases). Conclusions Our findings suggest good agreement in the interpretation of VRI data between different raters. In this respect, VRI might be helpful as a radiation free diagnostic tool for the management of pneumonia.

2010-01-01

211

The Shock and Vibration Bulletin. Part I.  

National Technical Information Service (NTIS)

Contents: Vibration responses of simple curved panels to high intensity random and discrete frequency noise; Random vibration using finite element approach; Frequency analysis of repetitive bursts of random vibration; Simplified random vibration computati...

1968-01-01

212

Effects of ischaemia upon reflex electromyographic responses evoked by stretch and vibration in human wrist flexor muscles.  

PubMed Central

1. The reflex electromyographic responses evoked in a wrist flexor muscle, flexor carpi radialis (f.c.r.), by forcible extension of the wrist ('stretch') and by vibration of the flexor tendon have been studied in normal subjects. Reflexes were elicited during the maintenance of a low level of voluntary flexor contraction (5% maximum). Stretch regularly produced a relatively prolonged (ca. 100 ms duration) increase in e.m.g. activity which was usually divisible into short-latency (ca. 25 ms, M1) and long-latency (ca. 50 ms, M2) peaks. Vibration produced a single, phasic peak, at short latency, with no sign of an accompanying long-latency wave comparable to the M2 stretch response. 2. Ischaemia was induced by inflation of a blood-pressure cuff around the upper arm and its effects upon the reflex patterns were studied. During ischaemia M1 stretch responses showed a more rapid and pronounced decline than did M2 responses and were abolished before voluntary power was appreciably affected. Vibration-evoked short-latency peaks changed in an essentially parallel manner to M1 stretch reflexes. During recovery from ischaemia M2 reflexes were restored before short-latency responses. 3. The patterns of reflex reductions in e.m.g. upon withdrawal of stimulation were also studied. Such troughs in activity, under non-ischaemic conditions, regularly commenced at short latency and were of relatively small amplitude. The records of several of the subjects, and particularly ones obtained during ischaemia, suggested that release of stretch (with concomitant stretch of antagonists) could elicit an additive, long-latency decline in e.m.g. The existence of any such separate, delayed component was never observed upon termination of vibration. 4. Measurements of changes in the latencies and durations of reflex components, accompanying the progression of ischaemia, indicated that depression of early reflex activity resulted in part from increases in the latencies of these initial peaks but predominantly reflected simultaneous and separate reductions in their amplitudes. 5. The generation of short-latency reflexes by stretch and vibration, both of which stimuli powerfully excite muscle spindle primary endings, and the marked susceptibility of these responses to ischaemia supports their being mediated by group Ia afferents. The contrasting behaviour of M2 stretch responses, both regarding their absence with vibration and their resistance to ischaemia, suggests that they depend crucially upon a separate group of reflex afferents.(ABSTRACT TRUNCATED AT 400 WORDS)

Cody, F W; Goodwin, C N; Richardson, H C

1987-01-01

213

Biodynamic response of the human body in the sitting position when subjected to vertical vibration  

Microsoft Academic Search

Previous studies of the location of those areas in which the sensation of vibration is perceived under whole body vertical vibration have underlined the predominance of the relative movement between thorax and pelvis. Experiments were designed to explore systematically the transmissibility between the pelvis and thorax. These were supplemented by measurements of mechanical impedance of the body and absorbed power.

P. M. Donati; C. Bonthoux

1983-01-01

214

The use of an Intensity Matching Technique to Evaluate Human Response to Whole-Body Vibration  

Microsoft Academic Search

Previous whole-body vibration intensity matching experiments have been reviewed and some of the different experimental methods and findings are discussed. An experiment has been conducted to investigate ‘ between ’ and ‘ within ’ subject variability in such experiments and to determine the effect of varying the frequency of the standard vibration against which other frequencies are matched. Although subjects

L. C. FOTHERGILL; M. J. GRIFFIN

1977-01-01

215

Dynamic responses of the in-plane and out-of-plane vibrations for an axially moving membrane  

NASA Astrophysics Data System (ADS)

The dynamic responses of both the in-plane and out-of-plane vibrations are investigated for an axially moving membrane. Using the extended Hamilton principle, equations of motion are derived for the moving membrane with no-slip boundary conditions at rollers. The equations of motion are discretized by using the Galerkin method and then the generalized-? time integration method is applied to compute the dynamic responses of the membrane. Based on the computed results, the responses are compared between the in-plane and out-of-plane vibrations. In addition, the effects of translating velocity/acceleration, critical speeds and velocity profiles on the dynamic behaviours for displacements and stresses are investigated and discussed.

Shin, Changho; Chung, Jintai; Hee Yoo, Hong

2006-11-01

216

A laboratory study to quantify the biomechanical responses to whole-body vibration: The influence on balance, reflex response, muscular activity and fatigue  

Microsoft Academic Search

To determine the acute effects of whole-body vibration (WBV) on the sensorimotor system and potentially on the stability of the spine, different biomechanical responses were tested before and after 60min of sitting, with and without vertical WBV, on four different days. Postures adopted while sitting and the simulated WBV exposure corresponded to large mining load haul dump (LHD) vehicles as

Brenda R. Santos; Christian Larivière; Alain Delisle; André Plamondon; Paul-Émile Boileau; Daniel Imbeau

2008-01-01

217

An ultrasonic elliptical vibration cutting device for micro V-groove machining: Kinematical analysis and micro V-groove machining characteristics  

Microsoft Academic Search

Micro V-groove machining characteristics of an ultrasonic elliptical vibration cutting (UEVC) device have been experimentally investigated and compared with the conventional micro V-grooving. From the initial experiments performed on ductile material such as aluminum and brass with a single crystal diamond cutting tool, it was found that the cutting force was significantly decreased and the formation of burrs at the

Gi Dae Kim; Byoung Gook Loh

2007-01-01

218

Research on the characteristics of the cutting force in the vibration cutting of a particle-reinforced metal matrix composites SiCp\\/Al  

Microsoft Academic Search

In this paper, turning experiments on the machining of composites SiCp\\/Al with a polycrystal diamond (PCD) tool have been carried out. The cutting force characteristics in ultrasonic vibration turning compared with those in common turning were studied. Through single factor experiments and multiple factor orthogonal experiments, the influences of three cutting parameters, namely cutting velocity, amount of feed and cutting

C. S Liu; B Zhao; G. F Gao; F Jiao

2002-01-01

219

Characteristics of cellulose sulfates with low degrees of substitution based on infrared spectra in the stretching vibration range of the hydroxyl groups  

Microsoft Academic Search

Various characteristics of the complex absorption band due to the stretching vibrations of the OH groups in the spectra of cellulose derivatives have been used by a number of authors to characterize intermolecular or intramolecular bonds [1], the process of esterification or ester hydrolysis [2, 3], etc. In [4], methylcelluloses with low degrees of substitution, in the form of films,

G. A. Petropavlovskii; G. G. Vasil'eva

1967-01-01

220

Equivalence of the Impedance Method and the Method of Amplitude?Frequency Characteristics for Investigations of Vibrations in Hydraulically Powered Supports  

Microsoft Academic Search

Two approaches to investigation of hydroelastic shock absorbers ensuring an efficient decrease in vibrations and noise in mobile machines have been presented. It has been shown that the parameters obtained by the method of amplitude-frequency characteristics more accurately correspond to the parameters of the physical model than the data computed with the impedance method.

N. A. Dokukova; P. N. Konon

2003-01-01

221

High-order Vibration Characteristics of Rotating Thin Shells and Hard-coating Damping Effects  

NASA Astrophysics Data System (ADS)

The high-order modes and the moving wave characteristics of rotating thin shell are investigated in this paper based on transfer matrix method when the damping effects of the hard-coating layers are applied on the shell. Firstly, the dynamic model of the thin shell is obtained based on the Love theory, with introducing centrifugal force and Coriolis force. Then, the transfer matrix formulas of the shell with partially coated layers at different segments are obtained under the clamped-free boundary condition, in which the mechanical property of the hard-coating material is simplified to be linear and isotropic. The modal characteristics of the shell are calculated numerically. The obtained higher order modal frequencies of the partially coated shells are compared with those of the bare shell. The effects of the material parameters and locations of the hard-coating layers are also illustrated based on the different modal characteristics., great care should be taken in constructing both.

Song, X. Y.; Ren, H. J.; Wang, X. P.; Li, X. J.; Han, Q. K.

2013-07-01

222

Display of response characteristics of seismic source arrays  

SciTech Connect

In seismic exploration wherein an array of seismic sources is moved along a line of exploration on the earth's surface and the reflections and/or refractions of seismic energy from the sources are recorded as seismograms, a method of displaying the response characteristics of the array is described which consists of: determining the amplitude response of the array at a plurality of locations at different azimuth angles and at different dip angles from the array; selecting equal values of determined amplitude response; and displaying contours of the equal values of amplitude response as a function of azimuth and dip angle in a stereoscopic polar projection.

Bowman, B.F.; Pann, K.; Pedeker, M.S.

1986-05-20

223

Musculoskeletal Response to Whole-Body Vibration During Fracture Healing in Intact and Ovariectomized Rats  

PubMed Central

This study investigated the effect of vibration on bone healing and muscle in intact and ovariectomized rats. Thirty ovariectomized (at 3 months of age) and 30 intact 5-month old female Sprague-Dawley rats underwent bilateral metaphyseal osteotomy of tibia. Five days later, half of the ovariectomized and of the intact rats were exposed to whole-body vertical vibration (90 Hz, 0.5 mm, 4 × g acceleration) for 15 min twice a day during 30 days. The other animals did not undergo vibration. After decapitation of rats, one tibia was used for computed tomographic, biomechanical, and histological analyses; the other was used for gene expression analyses of alkaline phosphatase (Alp), osteocalcin (Oc), tartrate-resistant acid phosphatase 1, and insulinlike growth factor 1. Serum Alp and Oc were measured. Mitochondrial activity, fiber area and distribution, and capillary densities were analyzed in M. gastrocnemius and M. longissimus. We found that vibration had no effect on body weight and food intake, but it improved cortical and callus densities (97 vs. 99%, 72 vs. 81%), trabecular structure (9 vs. 14 trabecular nodes), blood supply (1.7 vs. 2.1 capillaries/fiber), and oxidative metabolism (17 vs. 23 pmol O2/s/mg) in ovariectomized rats. Vibration generally increased muscle fiber size. Tibia biomechanical properties were diminished after vibration. Oc gene expression was higher in vibrated rats. Serum Alp was increased in ovariectomized rats. In ovariectomized rats, vibration resulted in an earlier bridging; in intact rats, callus bridging occurred later after vibration. The chosen vibration regimen (90 Hz, 0.5 mm, 4 × g acceleration, 15 min twice a day) was effective in improving musculoskeletal tissues in ovariectomized rats but was not optimal for fracture healing.

Stuermer, Ewa K.; Werner, Carsten; Wicke, Michael; Kolios, Leila; Sehmisch, Stephan; Tezval, Mohammad; Utesch, Clara; Mangal, Orzala; Zimmer, Sebastian; Dullin, Christian; Stuermer, Klaus M.

2010-01-01

224

Design and Characteristics of Mode-Coupling LiNbO3 Ultrasonic Motor Depended on Width-to-Length Ratio of the Stator Vibrator  

NASA Astrophysics Data System (ADS)

A miniature ultrasonic motor fabricated from a LiNbO3 rectangular plate was studied to improve its rotation characteristics. In this motor, the coupling modes of in-plane longitudinal and flexural modes caused by crystal anisotropy are used to realize a single-phase drive motor. The mode coupling vibrator is designed to have crystal cut angles and the width-to-length ratio W/L of the vibrator shape. In this study, we noted the new coupling condition of W/L? 0.84 compared with the conventional ratio of W/L=0.255. We considered the mechanism of the mode coupling and the design of the stator vibrator by finite element method analysis and experiments. From the results, we fabricated and investigated prototype motors of the vibrator with dimensions of 10× 2.55× 0.5 and 4.10× 3.48× 0.5 mm3. The newly designed motor with the vibrator of W/L=0.849 improved the motor characteristics for the equalization of rotation in both directions.

Hideki Tamura,; Takanori Morooka,; Yasuhiro Yamayoshi,; Manabu Aoyagi,; Takehiro Takano,; Seiji Hirose,

2010-07-01

225

Influence of resonators on the acoustic and propulsion performance characteristics of a ramjet ejector chamber under conditions with vibration hydrogen combustion  

NASA Astrophysics Data System (ADS)

The influence of acoustic resonators on the acoustic and propulsion performance characteristics of a ramjet ejector chamber under conditions with vibration hydrogen combustion was experimentally examined. In the study, resonators having identical throats and different cavity diameters were used. For fixed-volume resonators the best propulsion performance characteristics were achieved in the case in which the cavity diameter differed little from the resonator throat diameter.

Potapkin, A. V.; Moskvichev, D. Yu.

2008-09-01

226

Adaptive nonlinear vibration control of a Cartesian flexible manipulator driven by a ballscrew mechanism  

NASA Astrophysics Data System (ADS)

A flexible Cartesian manipulator is a coupling system with a moving rigid body and flexible structures. Thus, vibration suppression problem must be solved to guarantee the stability and control accuracy. A characteristic model based nonlinear golden section adaptive control (CMNGSAC) algorithm is implemented to suppress the vibration of a flexible Cartesian smart material manipulator driven by a ballscrew mechanism using an AC servomotor. The system modeling is derived to recognize the dynamical characteristics. The closed loop stability is analyzed based on the model. Also, an experimental setup is constructed to verify the adopted method. Experimental comparison studies are conducted for modal frequencies' identification and active vibration control of the flexible manipulator. The active vibration control experiments include set-point vibration control responses, vibration suppression under resonant excitation and simultaneous translating and vibration suppression using different control methods. The experimental results demonstrate that the controller can suppress both the larger and the lower amplitude vibration near the equilibrium point effectively.

Qiu, Zhi-cheng

2012-07-01

227

Relationship between measured apparent mass and seat-to-head transmissibility responses of seated occupants exposed to vertical vibration  

NASA Astrophysics Data System (ADS)

The “to-the-body” and “through-the-body” biodynamic response functions of the seated human body exposed to vertical vibration are measured and analyzed in an attempt to identify relationships between the apparent mass and seat-to-head transmissibility measures. The experiments involved 12 male subjects exposed to three magnitudes of whole-body vertical random vibration (0.25,0.5,1.0 m/s2 rms acceleration) in the 0.5 15 Hz frequency range, and seated with three back support conditions (none, vertical and inclined), and two different hands positions (hands in lap and hands on the steering wheel). The vertical apparent mass and seat-to-head transmissibility responses were acquired during the experiments, where the head acceleration was measured using a light and adjustable helmet-strap mounted accelerometer. The results showed that both the measured responses show good agreements in the primary resonances, irrespective of the back support condition, while considerable differences between the normalized apparent mass and seat-to-head transmissibility could be seen in the secondary resonance range for the two back supported postures. The seat-to-head transmissibility responses are further shown to be relatively sensitive to back supported postures compared with that of apparent mass responses. Relatively stronger effects of hands position were observed on the seat-to-head transmissibility responses compared with the apparent mass responses under back supported conditions. From the results, it is further concluded that seat-to-head transmissibility emphasizes the biodynamic response in the vicinity of the secondary resonance compared to the apparent mass. The seat-to-head transmissibility measure is thus considered to be more appropriate for describing seated body response to higher frequency vibration.

Wang, W.; Rakheja, S.; Boileau, P.-É.

2008-07-01

228

Identification of vibration loads on hydro generator by using hybrid genetic algorithm  

Microsoft Academic Search

Vibration dynamic characteristics have been a major issue in the modeling and mechanical analysis of large hydro generators. An algorithm is developed for identifying vibration dynamic characteristics by means of hybrid genetic algorithm. From the measured dynamic responses of a hydro generator, an appropriate estimation algorithm is needed to identify the loading parameters, including the main frequencies and amplitudes of

Shouju Li; Yingxi Liu

2006-01-01

229

THE PRINCIPLES UNDERLYING FORCE-LIMITED VIBRATION TESTING USING THE FREQUENCY-SHIFT METHOD  

Microsoft Academic Search

The traditional vibration test methodology of controlling the interface environment only to a motion based specification is often too conservative, inducing potentially excessive vibration responses at hardware resonant frequencies. This overtesting problem occurs because the smooth, input acceleration specification used in the test configuration is characteristic of a rigid, infinite impedance equipment mount; and not characteristic of the compliant, finite

Gregory L. Davis

230

Density response of a trapped Fermi gas: A crossover from the pair vibration mode to the Goldstone mode  

SciTech Connect

We consider the density response of a trapped two-component Fermi gas. Combining the Bogoliubov-deGennes method with the random phase approximation allows the study of both collective and single-particle excitations. Calculating the density response across a wide range of interactions, we observe a crossover from a weakly interacting pair vibration mode to a strongly interacting Goldstone mode. The crossover is associated with a depressed collective mode frequency and an increased damping rate, in agreement with density response experiments performed in strongly interacting atomic gases.

Korolyuk, A.; Kinnunen, J. J. [Department of Applied Physics, School of Science, Aalto University, P.O. Box 15100, FIN-00076 Aalto (Finland); Toermae, P. [Department of Applied Physics, School of Science, Aalto University, P.O. Box 15100, FIN-00076 Aalto (Finland); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106-4030 (United States)

2011-09-15

231

Combined dynamic stiffness matrix and precise time integration method for transient forced vibration response analysis of beams  

NASA Astrophysics Data System (ADS)

A method has been developed for determining the transient response of a beam. The beam is divided into several continuous Timoshenko beam elements. The overall dynamic stiffness matrix is assembled in turn. Using Leung's equation, we derive the overall mass and stiffness matrices which are more suitable for response analysis than the overall dynamic stiffness matrix. The forced vibration of the beam is computed by the precise time integration method. Three illustrative beams are discussed to evaluate the performance of the current method. Solutions calculated by the finite element method and theoretical analysis are also enumerated for comparison. In these examples, we have found that the current method can solve the forced vibration of structures with a higher precision.

Tang, Bin

2008-01-01

232

Dynamic Characteristics of Retinal Ganglion Cell Responses in Goldfish  

Microsoft Academic Search

A cross-correlation technique has been applied to quantify the de- pendence of the dynamic characteristics of retinal ganglion cell responses in goldfish on intensity, wavelength, spatial configuration, and spot size. Both theoretical and experimental evidence justify the use of the cross-correlation procedure which allows the completion of rather extensive measurements in a relatively short time. The findings indicate the following.

NICO A. M. SCHELLART; HENK SPEKREIJSE

1972-01-01

233

The roles, responsibilities and characteristics of audit committee in China  

Microsoft Academic Search

Purpose – The purpose of this paper is to investigate the perceptions of the roles, responsibilities and basic characteristics of audit committees (ACs) in the current business environment in China, from the perspectives of investors\\/creditors, independent directors (AC members), company officers and auditors. Design\\/methodology\\/approach – The study is conducted through a questionnaire survey of the four groups of stakeholders with

Z. Jun Lin; Jason Z. Xiao; Qingliang Tang

2008-01-01

234

Validation of Intra-Subject Variation in Biodynamic Responses of Seated Human Exposed to Whole-Body Vibration  

NASA Astrophysics Data System (ADS)

Many studies have been conducted to investigate the change in human response under various experimental conditions. Usually, these experiments were conducted using many subjects and the inter-subject variation was evaluated. However, the intra-subject variation in human response is also necessary for understanding the change in an individual's physical response to whole-body vibration (WBV). The aim of this study is to investigate the intra-subject variation in biodynamic responses (both apparent mass and seat-to-head transmissibility) of a seated human exposed to vertical whole-body vibration over time. In the experiments, nine male subjects were exposed to vertical random vibration (0.2-0.3 m/s2 in r.m.s.) in the 0-30Hz frequency range. The measurement variation was also evaluated, wherein the measurements were repeated five times without any change to form the “baseline” for each subject, and the intra-subject variations were evaluated by comparing their responses with these “baseline.” The intra-subject variation was examined from two different viewpoints: variation “within a day” and that “over several days.” To determine the intra-subject variation “within a day”, the five measurements were obtained at two-hour intervals on the same day. In the intra-subject variation “over several days”, the five measurements were obtained again, but at the same time of the day on five consecutive days. The results show that the intra-subject variations (both “within a day” and “over several days”) in biodynamic responses are larger than the “baseline.” However, when the variation “within a day” in biodynamic responses is compared to that “over several days,” no common trend is observed among subjects. Although the magnitude of intra-subject variation in biodynamic responses depends on each subject, both variations “within a day” and that “over several days” have a similar range of variation.

Park, Min Soo; Yoshimura, Takuya; Tamaoki, Gen

235

On the use of three-dimensional h- and p-version finite elements in solving vibration response problems  

Microsoft Academic Search

The potential for reliably solving vibration response problems by using h- and p-versions of the finite element (FE) method is investigated. Each FE model is based on full three-dimensional (3-D) displacement-based continuum theory. Special attention is given to the ability to handle thin and\\/or nearly incompressible elastic and viscoelastic materials. Steady-state time-harmonic problems in the low- and mid-frequency ranges are

M. Dalenbring; A. Zdunek

2005-01-01

236

Orbiting response in vortex-induced vibrations of a two-degree-of-freedom pivoted circular cylinder  

Microsoft Academic Search

Vortex-induced vibrations of a pivoted, rigid and circular cylinder were investigated experimentally. A cylinder with a mass ratio of 15.9 and a moment of inertia ratio of 66.8 was investigated at a constant Reynolds number of 2100 for a range of reduced velocities, 3.4?U??11.3, and damping ratios, 0.4%???1.1%. A novel experimental setup was designed to reproduce the orbiting response observed

S. Kheirkhah; S. Yarusevych; S. Narasimhan

237

EXPERIMENTAL STUDY ON BEHAVIOR OF KENCHI BLOCK MASONRY WALL WITH THE SHAKING TABLE TEST DURING BY VIBRATION CHARACTERISTICS AND FAILURE MECHANISM  

NASA Astrophysics Data System (ADS)

There are many earthquake damages of kenchi block masonry wall. So, we carried out experimental studies on the collapse mechanism of kenchi block masonry wall during earthquake. From these experimental data, i.e. acceleration response magnification, displacement and soil pressure were found to destroy the central wall vibrations caused by the subsidence of the embankment.

Ikemoto, Toshikazu; Mori, Masashi; Miyajima, Masakatsu; Hashimoto, Takao; Murata, Akira

238

Damage identification and health monitoring of structural and mechanical systems from changes in their vibration characteristics: A literature review  

SciTech Connect

This report contains a review of the technical literature concerning the detection, location, and characterization of structural damage via techniques that examine changes in measured structural vibration response. The report first categorizes the methods according to required measured data and analysis technique. The analysis categories include changes in modal frequencies, changes in measured mode shapes (and their derivatives), and changes in measured flexibility coefficients. Methods that use property (stiffness, mass, damping) matrix updating, detection of nonlinear response, and damage detection via neural networks are also summarized. The applications of the various methods to different types of engineering problems are categorized by type of structure and are summarized. The types of structures include beams, trusses, plates, shells, bridges, offshore platforms, other large civil structures, aerospace structures, and composite structures. The report describes the development of the damage-identification methods and applications and summarizes the current state-of-the-art of the technology. The critical issues for future research in the area of damage identification are also discussed.

Doebling, S.W.; Farrar, C.R.; Prime, M.B.; Shevitz, D.W.

1996-05-01

239

Bonding, vibrational, and electrical characteristics of CdS nanostructures embedded in polyvinyl alcohol matrix  

SciTech Connect

CdS nanocomposites have been grown in polyvinyl alcohol matrix by a chemical synthesis process. The transmission electron micrographs of nanocomposites synthesized at 70-90 deg. C temperature showed the growth of needlelike and junctionlike nanostructures. X-ray photoelectron spectroscopy analysis revealed the growth of stoichiometric CdS without the formation of any intermediate phases at the CdS-polyvinyl alcohol interface. Raman spectra of first order longitudinal optical phonon peak has been analyzed using phonon dispersion model to detect the surface phonon modes in CdS nanoneedles and wires. The origin of negative differential resistance behavior in current-voltage characteristics for junctionlike CdS nanocomposites has been discussed.

Mondal, S. P.; Dhar, A.; Ray, S. K. [Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur-721 302 (India); Chakraborty, A. K. [Laboratory for Mechanical Systems Engineering EMPA, Duebendorf, Zurich, CH-8600 (Switzerland)

2009-04-15

240

Characteristics of Electrorheological Responses in an Emulsion System  

PubMed

The characteristics of electrorheological (ER) responses in an emulsion system have been examined for the first time. The emulsion system consists of a chlorinated paraffin oil and a silicone oil; these two liquids have similar dielectric constants, but the former liquid is 1000 times more conductive than the latter liquid. The mismatch in electric properties between the dispersed phase and the dispersing medium can be reversed in an emulsion by inverting the phase distribution. Transient ER responses in the emulsion system have been studied over a range of shear rates following step changes (on/off) of an external dc electric field. The relative response strength characterizing the ER effect increases with the field strength and with the volume fraction of silicone oil, but decreases with increasing shear rate imposed. The paraffin oil-in-silicone oil emulsion exhibits a response much stronger than that observed in the phase-reversed silicone oil-in-paraffin oil emulsion. No negative ER response is detected in the silicone oil-in-paraffin oil emulsion. With an optical microscope, very different microscopic response characteristics are observed for the phase-reversed emulsions under static conditions, and this can be explained according to the leaky dielectric liquid model of Taylor. Copyright 1997 Academic Press. Copyright 1997Academic Press PMID:9441611

Pan; McKinley

1997-11-01

241

The effect of pinhole defect on vibrational characteristics of single walled carbon nanotube  

NASA Astrophysics Data System (ADS)

Carbon nanotubes are widely used in the design of nano sensors and actuators. Any defect in the manufactured nanotube affects its sensing performance and also influences its dynamic behavior. In this paper, the effect of pinhole defects on the dynamic characteristics of carbon nanotubes is investigated using continuum mechanics and the molecular structural mechanics approach. Dynamic analysis is performed for achiral nanotubes using the continuum mechanics approach with cantilever boundary condition, while for chiral nanotubes the molecular structural mechanics method is used. The shift of the principal frequency of the nanotube with number of pinhole defects on the length is observed and analyzed. The simulation results indicate that the existence of defects mostly affects the resonant frequency (bending rigidity) of single walled carbon nanotubes as the number of defects (pinhole) increase. Further, it is also observed that with the reduction in tube length, the variations in resonant frequency are enhanced. However, it is found that the frequency variation is less sensitive to the nanotube diameter.

Joshi, Anand Y.; Sharma, Satish C.; Harsha, S. P.

2011-03-01

242

Characteristic Timescales of Shoreface Response to Sea-Level Rise  

NASA Astrophysics Data System (ADS)

On open ocean, wave-dominated, sandy coasts, the response of the shore to sea-level rise is dominated not by inundation, but rather by the dynamic response of sediment transport processes to perturbations of the sea level. In a regime of sea level change, the predominant response of the wave-dominated shoreface depends upon the time-dependent response of the shoreface itself to changes in sea level as well as the potential changes to the shoreline. On a barrier coast, persistent, long-term changes to the shoreline are caused by storm overwash, which transports marine sediment landward, moving the shoreline boundary. Raised sea levels increase the impact and frequency of this overwash as relative barrier elevation is reduced. Overall, sediment transport processes on the shoreface remain poorly understood, complicating predictions of equilibrium shoreface shapes and even net sediment transport directions. However, presuming an equilibrium geometry, energetics-based, time-averaged relationships for cross-shore sediment transport provide a framework to understand the characteristic rates and types of shoreface response to perturbations to either the sea level or the shoreline boundary. In the case of a sea-level rise, we find that the dominant perturbation for a barrier system is not the sea-level rise itself, but rather the movement of the shoreline by overwash. The characteristic response time of the shoreface itself increases significantly at depth, suggesting that the lower shoreface response to a sea level change can be significantly delayed. We estimate the importance of extreme events on shoreface evolution by analyzing decade-long data series of wave characteristics along different open ocean coasts with barriers (Florida Gulf Coast, North Carolina, Marthas Vineyard). Analogous to the effect of floods in fluvial systems, although storm events can move significant sediment, the infrequency of the larger events limits their effect on the shoreface-the morphologically significant event for shoreface evolution has a return interval of less than two years. However, numerical simulations of tens of thousands of synthetic storm strikes at the same locations suggest that the return interval of storm events expected to cause significant overwash is longer, on the order of at least 50 years. To study the interactions between the characteristic timescales of shoreface evolution and barrier overwash, we apply a numerical model of barrier profile evolution that couples shoreface evolution with barrier overwash. This integrated model provides a tool to understand the response of barrier systems to changes in sea level over the late Holocene to the modern. The model also investigates the potential behavior of barrier systems as they (and their human occupants) respond to predicted increased rates of sea-level rise over the coming centuries.

Ashton, A. D.; Ortiz, A.; Lane, P.; Donnelly, J. P.

2011-12-01

243

Temperature-dependent fiber optic hydrogen gas sensor response characteristics  

Microsoft Academic Search

Dynamic response characteristics of silica fiber long-period grating with a modified cladding, composed of ˜10-100 nm nanoparticle palladium oxides thin film material prepared by a magnetron sputtering technique, have been investigated at several elevated temperatures with a 2%H2\\/98%N2 mixing gas concentration. The fiber cladding modified grating, without cladding chemical etching process, demonstrates 540 pm per 1% H2 sensitivity, a better

Hua Xia; Kung-Li Deng; Ken Bousman; Juntao Wu; Boon Lee; Renato Guida; Kevin McCarthy

2006-01-01

244

The negative and positive electrorheological behavior and vibration damping characteristics of colemanite and polyindene/colemanite conducting composite  

NASA Astrophysics Data System (ADS)

In this study, the electrorheological (ER) properties of colemanite and polyindene (94.8% PIn)/colemanite (5.2%) conducting composite were investigated by dispersion in silicone oil (SO). The zeta (?)-potentials and antisedimentation ratios of the materials were determined. Some parameters which affect the ER properties of all the dispersions such as the volume fraction, electric field strength (E), shear rate, frequency and temperature were investigated. The rather unusual behavior known as the negative ER effect was observed for colemanite/SO above E = 1.5 kV mm-1 and for PIn/colemanite/SO under all values of the electric field strength even at high volume fraction. This negative ER response was converted to a positive one by the addition of non-ionic surfactant. Furthermore, glycerol was used as a polar promoter and observed to enhance the ER activity of the colemanite/SO system. Creep-recovery tests were applied to all the dispersions studied to investigate their behavior under sustained shear stress. Finally, 28% and 30% vibration damping capacities were achieved using an automobile shock absorber for the glycerol/colemanite/SO and non-ionic surfactant/PIn/colemanite/SO systems under the E = 0.17 kV mm-1 condition, respectively.

Cetin, B.; Unal, H. I.; Erol, O.

2012-12-01

245

Experimental study of the characteristics of idle vibrations that result from axial forces and the spider positions of constant velocity joints  

Microsoft Academic Search

The vibrational characteristics of automotives during idling were studied experimentally by considering the axial forces of\\u000a the drive shaft and the spider positions in a constant-velocity joint. The generated forces, such as PF (plunging force) and\\u000a GAF (generated axial force) in the assembly of the drive-shaft module, were measured directly by an experimental apparatus.\\u000a Measurements of the GAF and PF

J. S. Sa; T. W. Kang; C. M. Kim

2010-01-01

246

Online adaptation to maximize the tradeoff between tuned vibration absorbers and tuned vibration dampers  

NASA Astrophysics Data System (ADS)

Tuned vibration absorbers and tuned vibration dampers are structurally similar, but there are significant differences in their implementation and tuning laws. Lightly damped absorbers are typically applied to primary systems experiencing tonal excitation and achieve a "near-zero" in the frequency response of the primary system. An additional resonant peak is added to the system, such, transients or a mismatch in the absorber's tuned condition may result in poor performance. In contrast, a mini-max approach is used in the design of tuned vibration dampers. The stiffness and damping are designed such that the maximum frequency response across a band of frequencies is minimized. The vibration damper is insensitive to changes in the excitation frequency, but does not generally achieve high performance, due to the added damping in the vibration damper. This paper presents a novel approach whereby the characteristics of both a vibration absorber and a vibration damper are utilized in a single device. During transients, the damping is increased with the goal of helping the system to settle quickly and to avoid operation at resonant conditions. As the vibration becomes tonal, the damping is reduced and good steady state performance is achieved.

Williams, Keith A.

2004-07-01

247

Actions of afferent impulses from muscle receptors on cerebellar purkyn? cells I. Responses to muscle vibration  

Microsoft Academic Search

Summary  Investigations were made in the decerebrate cat of the effect of muscle vibration on the activity of 342 Purkyn cells in the ipsilateral anterior lobe of the cerebellum. The effects were studied for three different muscle groups: in the hindlimb, the anterior tibial group (extensor digitorum longus, peroneus longus, brevis and tertius, and tibialis anterior) and gastrocnemius-soleus; and in the

K. Ishikawa; S. Kawaguchi; M. J. Rowe

1972-01-01

248

Nonlocal elasticity based magnetic field affected vibration response of double single-walled carbon nanotube systems  

NASA Astrophysics Data System (ADS)

The behaviour of carbon nanotubes in a magnetic field has attracted considerable attention in the scientific community. This paper reports the effects of a longitudinal magnetic field on the vibration of a magnetically sensitive double single-walled carbon nanotube system (DSWNTS). The two nanotubes of the DSWNTS are coupled by an elastic medium. The dynamical equations of the DSWNTS are derived using nonlocal elasticity theory. The two nanotubes are defined as an equivalent nonlocal double-Euler-Bernoulli beam system. Governing equations for nonlocal bending-vibration of the DSWNTS under a longitudinal magnetic field are derived considering the Lorentz magnetic force obtained from Maxwell's relation. An analytical method is proposed to obtain nonlocal natural frequencies of the DSWNTS. The influence of (i) nanoscale effects and (ii) strength of longitudinal magnetic field on the synchronous and asynchronous vibration phase of the DSWNTS is examined. Nonlocal effects with and without the effect of magnetic field are illustrated. Results reveal the difference (quantitatively) by which the longitudinal magnetic field affects the nonlocal frequency in the synchronous and asynchronous vibration modes of a DSWNTS.

Murmu, T.; McCarthy, M. A.; Adhikari, S.

2012-06-01

249

The Effect of Vibration on Postural Response of Down Syndrome Individuals on the Seesaw  

ERIC Educational Resources Information Center

|In order to better understand the role of proprioception in postural adjustments on unstable surfaces, we analyzed the effect of vibration on the pattern of muscle activity and joint displacements (ankle, knee and hip) of eight intellectually normal participants (control group-CG) and eight individuals with Down syndrome (DS) while balancing on…

Carvalho, Regiane Luz; Almeida, Gil Lucio

2009-01-01

250

Correlations between biodynamic characteristics of human hand–arm system and the isolation effectiveness of anti-vibration gloves  

Microsoft Academic Search

The objective of this study was to identify major individual factors that are directly associated with the effectiveness of anti-vibration gloves. Two series of experiments were performed. The first experiment measured the apparent mass of hand–arm system. The second one measured the transmissibility of a typical anti-vibration glove using a palm adapter method recommended in ISO 10819 (International Organisation for

R. G. Dong; T. W. McDowell; D. E. Welcome; W. P. Smutz

2005-01-01

251

Dose-response characteristics of an amorphous silicon EPID.  

PubMed

Electronic portal imaging devices (EPIDs) were originally developed for the purpose of patient setup verification. Nowadays, they are increasingly used as dosimeters (e.g., for IMRT verification and linac-specific QA). A prerequisite for any clinical dosimetric application is a detailed understanding of the detector's dose-response behavior. The aim of this study is to investigate the dosimetric properties of an amorphous silicon EPID (Elekta IVIEWGT) with respect to three photon beam qualities: 6, 10, and 25 MV. The EPID showed an excellent temporal stability on short term as well as on long term scales. The stability throughout the day was strongly influenced by warming up, which took several hours and affected EPID response by 2.5%. Ghosting effects increased the sensitivity of the EPID. They became more pronounced with decreasing time intervals between two exposures as well as with increasing dose. Due to ghosting, changes in pixel sensitivity amounted up to 16% (locally) for the 25 MV photon beam. It was observed that the response characteristics of our EPID depended on dose as well as on dose rate. Doubling the dose rate increased the EPID sensitivity by 1.5%. This behavior was successfully attributed to a dose per frame effect, i.e., a nonlinear relationship between the EPID signal and the dose which was delivered to the panel between two successive readouts. The sensitivity was found to vary up to 10% in the range of 1 to 1000 monitor units. This variation was governed by two independent effects. For low doses, the EPID signal was reduced due to the linac's changing dose rate during startup. Furthermore, the detector reading was influenced by intrabeam variations of EPID sensitivity, namely, an increase of detector response during uniform exposure. For the beam qualities which were used, the response characteristics of the EPID did not depend on energy. Differences in relative dose-response curves resulted from energy dependent temporal output characteristics of the accelerator. If ghosting is prevented from affecting the results and all dose-response effects are properly corrected for, the EPID signal becomes independent of dose rate, dose, and exposure time. PMID:16279061

Winkler, Peter; Hefner, Alfred; Georg, Dietmar

2005-10-01

252

Dose-response characteristics of an amorphous silicon EPID  

SciTech Connect

Electronic portal imaging devices (EPIDs) were originally developed for the purpose of patient setup verification. Nowadays, they are increasingly used as dosimeters (e.g., for IMRT verification and linac-specific QA). A prerequisite for any clinical dosimetric application is a detailed understanding of the detector's dose-response behavior. The aim of this study is to investigate the dosimetric properties of an amorphous silicon EPID (Elekta IVIEWGT) with respect to three photon beam qualities: 6, 10, and 25 MV. The EPID showed an excellent temporal stability on short term as well as on long term scales. The stability throughout the day was strongly influenced by warming up, which took several hours and affected EPID response by 2.5%. Ghosting effects increased the sensitivity of the EPID. They became more pronounced with decreasing time intervals between two exposures as well as with increasing dose. Due to ghosting, changes in pixel sensitivity amounted up to 16% (locally) for the 25 MV photon beam. It was observed that the response characteristics of our EPID depended on dose as well as on dose rate. Doubling the dose rate increased the EPID sensitivity by 1.5%. This behavior was successfully attributed to a dose per frame effect, i.e., a nonlinear relationship between the EPID signal and the dose which was delivered to the panel between two successive readouts. The sensitivity was found to vary up to 10% in the range of 1 to 1000 monitor units. This variation was governed by two independent effects. For low doses, the EPID signal was reduced due to the linac's changing dose rate during startup. Furthermore, the detector reading was influenced by intrabeam variations of EPID sensitivity, namely, an increase of detector response during uniform exposure. For the beam qualities which were used, the response characteristics of the EPID did not depend on energy. Differences in relative dose-response curves resulted from energy dependent temporal output characteristics of the accelerator. If ghosting is prevented from affecting the results and all dose-response effects are properly corrected for, the EPID signal becomes independent of dose rate, dose, and exposure time.

Winkler, Peter; Hefner, Alfred; Georg, Dietmar [Division of Medical Radiation Physics, Department of Radiotherapy and Radiobiology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Health Physics Division, ARC Seibersdorf Research GmbH, A-2444 Seibersdorf (Austria); Division of Medical Radiation Physics, Department of Radiotherapy and Radiobiology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria)

2005-10-15

253

Random vibration of mechanical and structural systems  

Microsoft Academic Search

This book addresses random vibration of mechanical and structural systems commonly encountered in aerospace, mechanical, and civil engineering. Techniques are examined for determining probabilistic characteristics of the response of dynamic systems subjected to random loads or inputs and for calculating probabilities related to system performance or reliability. Emphasis is given to applications.

T. T. Soong; Mircea Grigoriu

1993-01-01

254

A preliminary investigation into optimising the response of vibrating systems used for ultrasonic cutting  

NASA Astrophysics Data System (ADS)

The coupling of two non-linear oscillators is investigated, each with opposing non-linear overhang characteristics in the frequency domain as a result of positive and negative cubic stiffness. This leads to the definition of a two-degree-of-freedom Duffing oscillator in which such non-linear effects can be neutralised under certain dynamic conditions. The physical motivation for this system stems from applications in ultrasonic cutting in which an exciter drives a tuned blade. The exciter and the blade are both strongly non-linear, with features strongly reminiscent of positive and negative cubic effects. It is shown by means of approximate analysis that in the case of simple idealised coupled oscillator models a practically useful mitigating effect on the overall non-linear response of the system is observed when one of the cubic stiffnesses is varied. Experimentally, it has also been demonstrated that coupling of ultrasonic components with different non-linear characteristics can strongly influence the performance of the system and that the general behaviour of the hypothetical theoretical model is indeed borne out in practice.

Lim, F. C. N.; Cartmell, M. P.; Cardoni, A.; Lucas, M.

2004-05-01

255

The effects of acceleration on the mechanical impedance response of a primate model exposed to sinusoidal vibration.  

PubMed

Criteria for developing active and passive isolation mechanisms for reducing the effects of whole-body vibration exposure rely on a thorough understanding of the stiffness, damping, and resonance behaviors of the human or human surrogate body. Three Rhesus monkeys were exposed to seated whole-body sinusoidal vibration between 3 and 20 Hz at 0.69 and 3.47 msec-2 rms (0.1 and 0.5 g peak) accelerations. The mechanical impedance magnitude and phase were calculated as the ratio and phase relation between the transmitted force and input velocity, respectively, at the seat. The resultant profiles showed a significant decrease in the primary resonance frequency with increasing acceleration. At the lower acceleration level, a second lower impedance peak was observed at approximately 5 Hz. A three-mass, two degree-of-freedom model, which included upper torso and leg representation, was used to determine the mechanical parameters that best described the measured responses. The mean stiffness coefficients and the mean undamped natural frequencies associated with the upper torso and leg subsystems showed a significant decrease with increases in the acceleration level. The results of this study strongly suggested that nonlinear stiffness properties were responsible for the observed differences in the biodynamic response of the Rhesus monkey with acceleration level. PMID:8060029

Smith, S D; Kazarian, L E

256

Galerkin method for steady-state response of nonlinear forced vibration of axially moving beams at supercritical speeds  

NASA Astrophysics Data System (ADS)

The present paper investigates the steady-state periodic response of an axially moving viscoelastic beam in the supercritical speed range. The straight equilibrium configuration bifurcates in multiple equilibrium positions in the supercritical regime. It is assumed that the excitation of the forced vibration is spatially uniform and temporally harmonic. Under the quasi-static stretch assumption, a nonlinear integro-partial-differential equation governs the transverse motion of the axially moving beam. The equation is cast in the standard form of continuous gyroscopic systems via introducing a coordinate transform for non-trivial equilibrium configuration. For a beam constituted by the Kelvin model, the primary resonance is analyzed via the Galerkin method under the simply supported boundary conditions. Based on the Galerkin truncation, the finite difference schemes are developed to verify the results via the method of multiple scales. Numerical simulations demonstrate that the steady-state periodic responses exist in the transverse vibration and a resonance with a softening-type behavior occurs if the external load frequency approaches the linear natural frequency in the supercritical regime. The effects of the viscoelastic damping, external excitation amplitude, and nonlinearity on the steady-state response amplitude for the first mode are illustrated.

Zhang, Guo-Ce; Ding, Hu; Chen, Li-Qun; Yang, Shao-Pu

2012-03-01

257

DOSE–RESPONSE RELATIONSHIPS BETWEEN WHOLE-BODY VIBRATION AND LUMBAR DISK DISEASE—A FIELD STUDY ON 388 DRIVERS OF DIFFERENT VEHICLES  

Microsoft Academic Search

In a longitudinal study, the dose–response relationships between long term occupational exposure to whole-body vibration and degenerative processes in the lumbar spine caused by the lumbar disks were examined. From 1990 to 1992, 388 vibration-exposed workers from different driving jobs were examined medically and by lumbar X-ray. For each individual, a history of all exposure conditions was recorded, and a

S. Schwarze; G. Notbohm; H. Dupuis; E. Hartung

1998-01-01

258

Corticosteroid responsiveness and clinical characteristics in childhood difficult asthma  

PubMed Central

This study describes the clinical characteristics and corticosteroid responsiveness of children with difficult asthma (DA). We hypothesised that complete corticosteroid responsiveness (defined as improved symptoms, normal spirometry, normal exhaled nitric oxide fraction (FeNO) and no bronchodilator responsiveness (BDR <12%)) is uncommon in paediatric DA. We report on 102 children, mean±SD age 11.6±2.8 yrs, with DA in a cross-sectional study. 89 children underwent spirometry, BDR and FeNO before and after 2 weeks of systemic corticosteroids (corticosteroid response study). Bronchoscopy was performed after the corticosteroid trial. Of the 102 patients in the cross-sectional study, 88 (86%) were atopic, 60 (59%) were male and 52 (51%) had additional or alternative diagnoses. Out of the 81 patients in the corticosteroid response study, nine (11%) were complete responders. Of the 75 patients with symptom data available, 37 (49%) responded symptomatically, which was less likely if there were smokers in the home (OR 0.31, 95% CI 0.02–0.82). Of the 75 patients with available spirometry data, 35 (46%) had normal spirometry, with associations being BAL eosinophilia (OR 5.43, 95% CI 1.13–26.07) and high baseline forced expiratory volume in 1 s (FEV1) (OR 1.08, 95% CI 1.02–1.12). Of these 75 patients, BDR data were available in 64, of whom 36 (56%) had <12% BDR. FeNO data was available in 70 patients, of whom 53 (75%) had normal FeNO. Airflow limitation data was available in 75 patients, of whom 17 (26%) had persistent airflow limitation, which was associated with low baseline FEV1 (OR 0.93, 95% CI 0.90–0.97). Only 11% of DA children exhibited complete corticosteroid responsiveness. The rarity of complete corticosteroid responsiveness suggests alternative therapies are needed for children with DA.

Bossley, C.J.; Saglani, S.; Kavanagh, C.; Payne, D.N.R.; Wilson, N.; Tsartsali, L.; Rosenthal, M.; Balfour-Lynn, I.M.; Nicholson, A.G.; Bush, A.

2012-01-01

259

Method to characterize the vibrational response of a beetle type scanning tunneling microscope  

SciTech Connect

We describe a method for analyzing the external vibrations and intrinsic mechanical resonances affecting scanning probe microscopes by using the microscope as an accelerometer. We show that clear correlations can be established between the frequencies of mechanical vibrational modes and the frequencies of peaks in the tunnel current noise power spectrum. When this method is applied to our {open_quotes}beetle{close_quotes} type scanning tunneling microscope (STM), we find unexpected low frequency {open_quotes}rattling resonances{close_quotes} in the 500{endash}1700 Hz range that depend on the exact lateral position of the STM, in addition to the expected mechanical resonances of the STM above 4 kHz which are in good agreement with theoretical estimates. We believe that these rattling resonances may be a general problem for scanning probe microscopes that use some type of kinetic motion for coarse positioning. {copyright} {ital 1997 American Institute of Physics.}

Behler, S.; Rose, M.K.; Ogletree, D.F.; Salmeron, M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

1997-01-01

260

Hormonal responses to a single session of wholebody vibration exercise in older individuals  

Microsoft Academic Search

ObjectiveWhole-body vibration (WBV) has been recently suggested as an alternative form of exercise. In this study, the acute effects of a single session of WBV exercise on anabolic hormones in aged individuals were analysed.DesignA randomised cross-over trial design was used.SettingsGeriatrics Department, Woodend Hospital.Participants20 individuals (9 men and 11 women; median age 70 years (range 66 to 85 years) volunteered in

M. Cardinale; R. L. Soiza; J. B. Leiper; A. Gibson; W. R. Primrose

2010-01-01

261

Epidemiological study of vibration syndrome in response to total hand-tool operating time  

Microsoft Academic Search

The correlation between the severity of vibration syndrome and hand-tool operating time in chain saw workers has been studied. The total chain saw operating time was calculated by using the equation: chain saw operating hours\\/day X days\\/year X years, and 266 chain saw operators were classified into four groups (0-2000 h, 2000-5000 h, 5000-8000 h, over 8000 h). Forty-six forestry

K Miyashita; S Shiomi; N Itoh; T Kasamatsu; H Iwata

1983-01-01

262

Secondary Periodicity in the Structural and Vibrational Characteristics of 3,3-DIMETHYLCYCLOPROPENES - and Monosubstituted by -X{(CH_3)}_3 (x = C, Si, Ge, Sn, Pb)  

NASA Astrophysics Data System (ADS)

The regularities of changes in the structural parameters and vibrational wavenumbers have been traced for certain moieties of the title compounds. The optimized geometrical parameters and the force fields of disubstituted 3,3-dimethylcyclopropenes and monosubstituted 3,3-dimethylcyclopropenes were determined at the HF/3-21G* and DDAll levels, respectively. The choice of these theoretical levels was brought about by peculiarities of GAUSSIAN 03 suite of programs for Sn and Pb atoms. The theoretical vibrational wavenumbers were calculated from the corresponding scaled force fields. The regularities obtained in the form of the zigzag lines are analogous to regularities that are characteristic to the atoms of the 14 (IVA) group of the Mendeleyev Periodic Table. This is known as the secondary periodicity phenomenon. Yu. N. Panchenko, G. R. De Maré, A. V. Abramenkov, and A. de Meijere, Spectrochim. Acta 65A, 575 (2006). G. R. De Maré, Yu. N. Panchenko, and A. V. Abramenkov, Spectrochim. Acta 67A, 1094 (2007).

Panchenko, Yu. N.; Abramenkov, A. V.; de Maré, G. R.

2009-06-01

263

Linear Response Properties Required to Simulate Vibrational Spectra of Biomolecules in Various Media  

NASA Astrophysics Data System (ADS)

We here present a combined VA, VCD, Raman and ROA vibrational study of phenyloxirane. We have simulated the vibrational absorption (VA), also called IR, vibrational circular dichroism (VCD), Raman scattering and Raman optical activity (ROA) intensities utilizing the density functional theory (DFT) B3LYP hybrid exchange correlation functional and other exchange-correlation functionals (PBE, PW91, PBE1) with the 6-31G(d,p), 6-31++G(d,p), cc-pVDZ, aug-cc-pVDZ, cc-pVTZ and augmented correlation consistent polarized valence triple zeta (aug-cc-pVTZ) basis sets. Previously authors have focused on either the VA and VCD spectra or the Raman and ROA spectra of molecules, since the experimental and theoretical instruments and methods for calculating these quantities are quite distinct. Here we show that the combined analysis gives more information, especially with respect to the electric dipole, magnetic dipole, electric dipole - electric dipole polarizability, electric dipole - electric quadrupole polarizability and electric dipole - magnetic dipole polarizability changes during the various induced transitions. The coupling of vibrational and electronic excitations may be used to aid in understanding the photo induced chemical reactivity observed in many systems. This work is a continuation of our goal to interpret the results of experimental studies on the basis of theoretical results, which can help to understand the structure and function of proteins, other biomolecules and ligands in their native environments. As the physical tools used to observe and study biological processes have evolved, so have the theoretical methods and models to interpret, understand and completely utilize the results of these new measurements. The work on developing methods for modeling amino acids, peptides, proteins and ligands in both the non aqueous (lipid) and aqueous environments has involved, of course, many groups. A review of our contributions to this field has recently been presented. In addition to interpreting existing and new experimental results, we will discuss structural, energetic, conformational, and vibrational studies on a variety of systems that have been used to test and validate levels of theory, and in addition to suggest modifications to existing levels of theory, which can make them even more useful than they currently are.

Jalkanen, K. J.; Würtz Jürgensen, V.; Degtyarenko, I. M.

264

Comparison of the Driving-Point Impedance and Transmissibility Techniques in Describing Human Response to Whole-Body Vibration.  

National Technical Information Service (NTIS)

The driving-point impedance and transmissibility techniques were applied and compared to further evaluate the contribution of specific anatomical structures or regions in producing resonance behavior and nonlinear response characteristics. Five human subj...

S. D. Smith

1994-01-01

265

EFFECTS OF 6-WEEK WHOLE BODY VIBRATION TRAINING ON THE REFLEX RESPONSE OF THE ANKLE MUSCLES: A RANDOMIZED CONTROLLED TRIAL  

PubMed Central

Background: The ligament sprain of the lateral ankle is the most frequent injury that occurs when participating in sports. Whole body vibration (WBV) is a training method that has been recently introduced as a rehabilitative tool for treatment of athletes. It has been hypothesized that the transmission of mechanical oscillations from the vibrating platform may lead to physiological changes in muscle spindles, joint mechanoreceptors, as well as improve balance. Propose: The aim of this study was to assess the effects of a 6?week WBV training program on the reflex response mechanism of the peroneus longus (PL), peroneus brevis (PB) and anterior tibialis (AT) muscles in ankle inversion at 30º from horizontal, in a static position. Methods: This study was a single?blinded and randomized controlled trial. Forty?four healthy, physically active participants were randomly split into two groups: the experimental group (n = 26) (the WBV training) and control group (n = 18). Reaction time (RT), maximum electromyographic (EMG) peak (peak EMG), time to the maximum peak EMG (peak EMG time) and reflex electrical activity of all the muscles were assessed before and after the WBV training through surface EMG. Results: After 6?weeks WBV training, there were no significant changes in the variables analysed for all the muscles involved. Conclusion: A 6?week WBV training does not improve the reflex response mechanism of the lateral stabilizing muscles of the ankle. Level of evidence: 1b

Rubio, Jacobo A.; Ramos, Domingo J.; Esteban, Paula; Mendizabal, Susana; Jimenez, Fernando

2013-01-01

266

Response characteristics of muscle afferents in the domestic duck  

PubMed Central

1. Response patterns of 116 muscle stretch receptor units isolated from the sciatic nerve of the duck have been studied, and the units classified as muscle spindles and tendon organs. 2. Units classified as spindles had low threshold tensions for maintained discharge. From conduction—velocity measurements, the calculated fibrediameter spectrum appears to be unimodal, ranging from 5 to 11-12 ?m. 3. Spindle units showed essentially `in parallel' behaviour, though increase in initial tension often led to the appearance of `in series' responses. Although apparent `?-excitation' during maximal tetanic contractions was a common occurrence, no direct evidence of ?-innervation of spindles was obtained. 4. Evidence has been obtained for motor innervation of spindles by fibres distinct from those constituting the alpha supply to extrafusal muscle fibres. Afferent response attributable to this fusimotor innervation is influenced by initial tension and stimulus-frequency. Electrical thresholds for fusimotor responses ranged from 1·1 to 4·03 times ? maximum. 5. Tendon organ units consistently showed `in series' response patterns during muscle contractions. They were not influenced by stimulation of the high-threshold efferent nerve supply to the muscles. 6. Threshold tensions required for maintained discharge in tendon organ units from m. gastrocnemius pars lateralis were characteristically high; however, many units from m. flexor perforans et perforatus d. 3 had unexpectedly low mechanical thresholds. The calculated fibre-diameter spectrum for tendon organ units is unimodal, ranging from 4-7 to 10-11 ?m. As in mammals, they contribute to the coarse-fibre component in the muscle nerve and include the fastest fibres present.

Dorward, Patricia K.

1970-01-01

267

MODEL REDUCTION IN STRUCTURAL VIBRATION CONTROL AND ITS APPLICATION  

Microsoft Academic Search

In this paper, a model reduction method for structural vibration control is presented. The method directly uses a set of physical coordinates as the states of the reduced order model to be constructed such that it will provide the same frequency response characteristics as the original full model within the frequency range of interests. Frequency characteristics of a reduced order

Wei Liu

268

A theoretical study on the influence of the track on train-induced ground vibration  

Microsoft Academic Search

An investigation is presented on the nature of train-induced ground vibration propagation. It is based on a theoretical model for the track and a layered ground. Results are given of the responses of the ground and track to a moving harmonic or quasi-static load on the rails. The dispersion characteristics of the propagating modes of vibration in the track and

X. Sheng; C. J. C. Jones; D. J. Thompson

2004-01-01

269

Blasting vibration criterion for a rock-anchored beam in an underground powerhouse  

Microsoft Academic Search

The design approach for a rock-anchored beam (RAB) in an underground powerhouse is briefly introduced, and the dynamic response characteristics of an RAB under blasting vibration are presented. It is found that the key to ensure the safety of RAB under blasting vibration is to prevent the split of the bonding interface between the RAB and a vertical rock wall,

Ming Chen; Wenbo Lu; Changping Yi

2007-01-01

270

Vibration study of the APS storage ring 0. 8 meter quadrupole magnet/magnet support assembly  

SciTech Connect

The objectives of this study are as follows: Determine the vibration characteristics (frequency, damping, and mode shapes) of the magnet on prototypic supports (the actual mounting system used to mount the magnet on the girder). Measure system response to ambient floor motion. Measure the effect of various modifications to determine if the magnet response can be modified to minimize unwanted response characteristics. Modifications investigated include support schemes, increasing system damping, and increasing mechanical rigidity. Measure system response to coolant flow. Determine vibrational characteristics of a large concrete block placed on a concrete floor, including response to ambient floor motions.

Jendrzejczyk, J.A.; Wambsganss, M.W.; Smith, R.K.

1991-06-01

271

Ultrasonic vibration-assisted pelleting of wheat straw: a predictive model for energy consumption using response surface methodology.  

PubMed

Cellulosic biomass can be used as a feedstock for biofuel manufacturing. Pelleting of cellulosic biomass can increase its bulk density and thus improve its storability and reduce the feedstock transportation costs. Ultrasonic vibration-assisted (UV-A) pelleting can produce biomass pellets whose density is comparable to that processed by traditional pelleting methods (e.g. extruding, briquetting, and rolling). This study applied response surface methodology to the development of a predictive model for the energy consumption in UV-A pelleting of wheat straw. Effects of pelleting pressure, ultrasonic power, sieve size, and pellet weight were investigated. This study also optimized the process parameters to minimize the energy consumption in UV-A pelleting using response surface methodology. Optimal conditions to minimize the energy consumption were the following: ultrasonic power at 20%, sieve size at 4 mm, and pellet weight at 1g, and the minimum energy consumption was 2.54 Wh. PMID:23859359

Song, Xiaoxu; Zhang, Meng; Pei, Z J; Wang, Donghai

2013-07-01

272

Resonance response of vibrational transitions in amino acid crystals to millimeter radiation  

NASA Astrophysics Data System (ADS)

Results of study of resonance interaction of low-energy radiation in the interval of 37 - 53 GHz with (beta) -alanine and (alpha) -glycine monocrystals have been presented. The role of form-factor effect was investigated. It was revealed that the MMW irradiation of aminoacid crystal in a process of infrared reflection spectra registration led to considerable intensity redistribution and to bands thin structure manifestation of the deformational vibrations of NH3+ and CO2- groups near 15000 cm-1. Resonance character of millimeter wave influence was determined. In the action spectra numerous resonances with the halfwidths from 40 to 80 MHz were observed.

Berezhinsky, Leonid I.; Dovbeshko, Galina I.; Lisitsa, Mikhail P.; Litvinov, Grigory S.; Andreev, E. A.

1994-08-01

273

Seasonal variations in vibrational spectra of the sea surface nanolayer and their relation to characteristic parameters for phytoplankton activity  

NASA Astrophysics Data System (ADS)

The sea surface nanolayer is a very thin organic substance layer, down to monomolecular thickness. It is found on top of the sea surface microlayer, which in turn comprises roughly the uppermost millimeter of the water column. The nanolayer constitutes the actual interface between ocean and atmosphere and plays an important role in all exchange processes of matter and energy between ocean and atmosphere. Nevertheless, knowledge about formation and development of the sea surface nanolayer in the course of the year is very limited. In this study we present surface-specific observations of the sea surface nanolayer development over a period of three and a half years. Samples of the sea surface have been taken monthly at Boknis Eck Time Series Station (Eckernförde Bay, southwestern Baltic Sea) by screen sampling. From surface-sensitive vibrational spectra obtained by nonlinear sum frequency generation spectroscopy (SFG), information on amount, structure and composition of the organic nanolayer material was extracted. SFG has been introduced by us as a new method to study the ocean nanolayer quite recently [1,2]. The abundance of nanolayer material was found to follow a pronounced yearly periodicity, with larger amounts of material present from mid to end of summer. A substantial time lag of about 2.5 months between spring algal bloom maxima and abundance maxima of nanolayer material has been observed. In contrast to common perception, this shows that high phytoplankton abundance and pronounced nanolayers are not directly related to each other. Variations in the appearance of the spectra serve as indicators for changes in structure and chemical composition of the nanolayer. The accumulation of carbohydrate-rich material in late summer provides a possible explanation for the observed spectral changes. We propose that sloppy feeding of zooplankton as well as photochemical and/or microbial processing of organic material present in the microlayer is responsible for the periodicity of nanolayer intensity and its temporal shift with respect to other influential factors. References [1] K. Laß, G. Friedrichs, J. Geophys. Res. 116 (2011) C08042/1-15 [2] K. Laß, J. Kleber, G. Friedrichs, Limnol. Oceanogr.: Methods 8 (2010) 216-228

Laß, Kristian; Bange, Hermann W.; Friedrichs, Gernot

2013-04-01

274

Effects of a perilymphatic fistula on the passive vibration response of the basilar membrane.  

PubMed

In this study, a three-dimensional finite-element model of the passive human cochlea was created. Dynamic behavior of the basilar membrane caused by the vibration of the stapes footplate was analyzed considering a fluid-structure interaction with the cochlear fluid. Next, the effects of a perilymphatic fistula (PLF) on the vibration of the cochlea were examined by making a small hole on the wall of the cochlea model. Even if a PLF existed in the scala vestibuli, a traveling wave was generated on the basilar membrane. When a PLF existed at the basal end of the cochlea, the shape of the traveling wave envelope showed no remarkable change, but the maximum amplitude became smaller at the entire frequency range from 0.5 to 5kHz and decreased with decreasing frequency. In contrast, when a PLF existed at the second turn of the cochlea, the traveling wave envelope showed a notch at the position of the PLF and the maximum amplitude also became smaller. This model assists in elucidating the mechanisms of hearing loss due to a PLF from the view of dynamics. PMID:22115725

Koike, Takuji; Sakamoto, Chiaki; Sakashita, Tasuku; Hayashi, Ken; Kanzaki, Sho; Ogawa, Kaoru

2011-11-15

275

High-temperature vibrational response and high-pressure melting curve of lead  

NASA Astrophysics Data System (ADS)

The concept of mean-field potential (MFP) is an adequate description to evaluate vibrational contribution to the Helmholtz free energy at finite temperatures and pressures for condensed-state of matter. Once the total free energy is available, as an explicit function of temperature and volume (?pressure), several thermodynamic properties can be calculated numerically using the text-book equations. While the MFP approach is robust, its applicability is extended to estimate atomic and vibrational properties of materials within the Debye model. In the present scheme, we propose energy-calculation based formula to calculate the Debye temperature. We discuss temperature dependence of Debye temperature, entropy and atomic mean-square displacements for elemental fcc-Pb. It is demonstrated that the present extended MFP (EMFP) scheme, allows one to include the effect of three choices for thermodynamic Grüneisen parameter, namely, due to Slater, due to Dugdale and MacDonald and the one due to free volume theory, on different physical properties. A much debatable dynamical phenomenon, a high pressure melting curve is also obtained, where melting temperature is now explicitly dependent on these three assumptions for the Grüneisen parameter. Results so obtained are discussed and compared with the recent first principles theoretical and experimental findings.

Bhatt, N. K.; Thakore, B. Y.; Vyas, P. R.; Jani, A. R.

2010-08-01

276

The response characteristics of tetrazolium violet solutions to gamma irradiation  

NASA Astrophysics Data System (ADS)

The dosimetry characteristics of various solutions of tetrazolium violet, TV, (2,5-diphenyl-3-(1-naphthyl)-2H-tetrazolium chloride) to gamma irradiation are reported. The optical absorption spectra of these solutions show peaks between 400 and 600 nm with a shoulder at around 550 nm. The dose response of the optical absorbance values of aqueous and aqueous-alcoholic solutions containing different concentrations of TV was measured in the 250 Gy up to 75 kGy dose range. The formation of formazan product was observed due to radiolytic reduction in both solutions. Its formation was found more pronounced in N2-saturated as well as in alkaline solutions. The results indicate that the 1 mM TV solution can be used for food irradiation and medical sterilization dosimetry at gamma irradiation facilities.

Emi-Reynolds, G.; Kovács, András; Fletcher, J. J.

2007-08-01

277

Experimental IR and Raman spectra and quantum chemical studies of molecular structures, conformers and vibrational characteristics of L-ascorbic acid and its anion and cation  

NASA Astrophysics Data System (ADS)

IR and spectra of the L-ascorbic acid ( L-AA) also known as vitamin C have been recorded in the region 4000-50 cm -1. In order to make vibrational assignments of the observed IR and Raman bands computations were carried out by employing the RHF and DFT methods to calculate the molecular geometries and harmonic vibrational frequencies along with other related parameters for the neutral L-AA and its singly charged anionic ( L-AA -) and cationic ( L-AA +) species. Significant changes have been found for different characteristics of a number of vibrational modes. The four ?(O-H) modes of the L-AA molecule are found in the order ?(O 9-H 10) > ?(O 19-H 20) > ?(O 7-H 8) > ?(O 14-H 15) which could be due to complexity of hydrogen bonding in the lactone ring and the side chain. The C dbnd O stretching wavenumber ( ?46) decreases by 151 cm -1 in going from the neutral to the anionic species whereas it increases by 151 cm -1 in going from the anionic to the cationic species. The anionic radicals have less kinetic stabilities and high chemical reactivity as compared to the neutral molecule. It is found that the cationic radical of L-AA is kinetically least stable and chemically most reactive as compared to its neutral and anionic species.

Yadav, R. A.; Rani, P.; Kumar, M.; Singh, R.; Singh, Priyanka; Singh, N. P.

2011-12-01

278

Nonlinear Analysis and Experiments on Torsional Vibration of a Rotor with a Centrifugal Pendulum Vibration Absorber  

Microsoft Academic Search

In the rotating machinery, such as automobile engines, the driving torque changes periodically and torsional vibrations occur. In this study, the dynamic characteristics of centrifugal pendulum vibration absorbers which are used to suppress torsional vibrations are investigated both theoretically and experimentally. In the theoretical analysis, the nonlinear characteristics are taken into consideration under the assumption that the pendulums vibrate with

Yukio Ishida; Tsuyoshi Inoue; Taishi Kagawa; Motohiko Ueda

2008-01-01

279

Flow-induced vibration and instability of some nuclear-reactor-system components. [PWR  

SciTech Connect

The high-velocity coolant flowing through a reactor system component is a source of energy that can induce component vibration and instability. In fact, many reactor components have suffered from excessive vibration and/or dynamic instability. The potential for detrimental flow-induced vibration makes it necessary that design engineers give detailed considerations to the flow-induced vibration problems. Flow-induced-vibration studies have been performed in many countries. Significant progress has been made in understanding the different phenomena and development of design guidelines to avoid damaging vibration. The purpose of this paper is to present an overview of the recent progress in several selected areas, to discuss some new results and to indentify future research needs. Specifically, the following areas will be presented: examples of flow-induced-vibration problems in reactor components; excitation mechanisms and component response characteristics; instability mechanisms and stability criteria; design considerations; and future research needs.

Chen, S.S.

1983-01-01

280

Vestibular evoked myogenic potentials to sound and vibration: characteristics in vestibular migraine that enable separation from Menière’s disease  

Microsoft Academic Search

Objectives: It can be difficult to distinguish vestibular migraine (VM) from Menière’s disease (MD) in its early stages. Using vestibular-evoked myogenic potentials (VEMPs), we sought to identify test parameters that would help discriminate between these two vestibular disorders.Methods: We first recorded ocular and cervical VEMPs (oVEMP\\/cVEMP) to air-conducted clicks and bone-conducted vibration in 30 control participants, 30 participants with clinically

Rachael L Taylor; Alessandro S Zagami; William PR Gibson; Deborah A Black; Michael G Halmagyi; Miriam S Welgampola

2012-01-01

281

A stochastic averaging approach for printed circuit boards with nonlinear damping characteristics subjected to random vibration loads  

Microsoft Academic Search

Today many electronic devices consist of plate-like printed circuit boards carrying electric and electronic components mounted in some sort of housing. Depending on the application, these electronic devices may be subjected to severe random vibration loads over their lifetime, e.g. in automotive or aerospace environments. The present work shows that although state-of-the-art printed circuit boards are typically structurally linear with

N. Hoffmann; L. Gaul

2006-01-01

282

[Characteristics of work schedules of miners exposed to vibration in placer and ore mines in the North-West].  

PubMed

The contributors review the peculiarities of modelling the labour regimen for the vibration-affected professions in the North-West, based on the dosage-related approach, inasmuch as the existing techniques of ore deposits elaboration (chamber-long face and magnification of ore), and the organization of pit works on cyclogrammes, did not allow a practical application of the labour regimen recommendations proposed by the USSR Ministry of Health. PMID:1817080

Loginov, A A; Kim, G N

1991-01-01

283

Short latency responses in the averaged electro-oculogram elicited by vibrational impulse stimuli applied to the skull: could they reflect vestibulo-ocular reflex function?  

PubMed Central

Objectives: To investigate whether vibrational impulse stimuli applied to the skull can be used to evoke the vestibulo-ocular reflex (VOR) and detect vestibular lesions. Methods: Twenty four patients with unilateral vestibular loss (UVD), five with bilateral vestibular loss, two with ocular palsies, and 10 healthy subjects participated. Vibrations of the skull were induced with head taps and with a single period of 160 Hz tone burst on the inion, vertex, and the mastoids while the patients viewed a distant target. Several patients were also examined while viewing a near target, with eccentric gaze and in tilted postures. Responses were recorded by EOG. Results: Responses occurred between 5 ms and 20 ms and seemed to be compensatory to the second phase of the sine wave of vibration impulse and were greatly diminished/absent in patients with bilateral VD and ocular palsies. The patients with UVD had asymmetrical responses in the vertical EOG with stimuli applied on the inion and vertex, with enhancement of the response amplitude on the side of vestibular loss and/or diminution on the healthy side. The asymmetry ratios between the healthy subjects and patients with UVD, and among patients with UVD were statistically significant. Some gaze and positional influences could be demonstrated consistent with otolithic reflexes. Conclusion: If the asymmetric responses to skull vibration in UVD result from passive oscillatory movements of the orbital tissues they may reflect the otolith mediated sustained skew torsion. Conversely, if generated by active eye movements, their likely origin is a phasic VOR.

Jombik, P; Bahyl, V

2005-01-01

284

Whole-body vertical biodynamic response characteristics of the seated vehicle driver  

Microsoft Academic Search

The vertical driving-point mechanical impedance characteristics applicable to seated vehicle drivers are measured in the 0.625–10Hz frequency range with excitation amplitudes ranging from 1.0 to 2.0ms?2 using a whole-body vehicular vibration simulator. The measurements are performed for seated subjects with feet supported and hands held in a driving position. Variations in the seated posture, backrest angle, and nature and amplitude

P.-É. Boileau; S. Rakheja

1998-01-01

285

Structural-dynamic-response characteristics of Darrieus vertical-axis wind turbines  

SciTech Connect

Operational experience at Sandia National Laboratories (SNL) with Darrieus-type vertical axis wind turbines (VAWTs) has indicated that a variety of dynamic issues can affect structural performance of the system. The observation and analysis of structural dynamic responses in the VAWT have been divided among three major aspects of the system; namely rotor vibrations, torsional response of the drive train, and transverse vibrations of the cables. This division is not arbitrary, but is rather because the response of these subsystems can be accurately decoupled from each other in most circumstances. This paper will present only a brief summary of the efforts now underway at SNL in the area of structural dynamics. The emphasis will be on discussing the status of our analytical tools, the quantity and quality of existing experimental confirmation data, and the implications structural dynamic issues have on rotor design.

Sullivan, W.N.

1981-01-01

286

Vibration in Grease Lubricated Bearing Systems  

Microsoft Academic Search

In this study a dynamic bearing apparatus is designed, developed and used to evaluate noise and vibration of bearings lubricated with various greases under different operating conditions. Eight different greases are evaluated for their vibration and noise characteristics. The threshold, kurtosis and mean square methods are used to quantify grease vibration and rank the greases based on their bearing vibration.

Sundar Ramamurthy; Charles M. Krousgrill; Farshid Sadeghi

2000-01-01

287

Qy-excitation resonance Raman spectra of chlorophyll a and bacteriochlorophyll c/d aggregates. Effects of peripheral substituents on the low-frequency vibrational characteristics.  

PubMed

Low-frequency (80-700 cm-1) Qy-excitation resonance Raman (RR) spectra are reported for thin-solid-film aggregates of several chlorophyll (Chl) a and bacteriochlorophyll (BChl) c/d pigments. The pigments include Chl a, pyrochlorophyll a (PChl a), methylpyrochloropyllide a (MPChl a), methylbacteriochloropyllide d (MBChl d), [E,M] BChl cS, [E,E] BChl cF, and [P,E] BChl cF. The BChl c/d's are the principal constituents of the chlorosomal light-harvesting apparatus of green photosynthetic bacteria. Together, the various Chl a's and BChl c/d's represent a series in which the peripheral substituent groups on the chlorin macrocycle are varied in systematic fashion. All of the Chl a and BChl c/d aggregates exhibit rich low-frequency vibrational patterns. In the case of the BChl c/d's, certain modes in the very low-frequency region (100-200 cm-1) experience exceptionally strong Raman intensity enhancements. The frequencies of these modes are qualitatively similar to those of oscillations observed in femtosecond optical experiments on chlorosomes. The RR data indicate that the low-frequency vibrations are best characterized as intramolecular out-of-plane deformations of the chlorin macrocycle rather than intermolecular modes. The coupling of the out-of-plane modes in turn implies that the Qy electronic transition(s) of the aggregate have out-of-plane character. The RR spectra of the BChl c/d's also reveal that the nature of the alkyl substituents at the 8 and 12 positions of the macrocycle plays an important role in determining the detailed features of the low-frequency vibrational patterns. The frequencies of the modes are particularly sensitive to larger substituent groups whose conformations may be more easily perturbed in the tightly packed aggregates. These factors also make aggregates of pigments containing larger substituents more susceptible to structural, electronic, and vibrational inhomgeneities. Collectively, the RR studies of the various pigments delineate the factors which influence the low-frequency vibrational characteristics of chlorosomal aggregates. PMID:11539301

Diers, J R; Zhu, Y; Blankenship, R E; Bocian, D F

1996-05-16

288

Determination of reference values of apparent mass responses of seated occupants of different body masses under vertical vibration with and without a back support  

Microsoft Academic Search

The biodynamic response of human body seated without a back support and exposed to vertical whole-body vibration have been standardized in ISO 5982 and DIN 45676 in terms of driving-point mechanical impedance and apparent mass. A comparison of ranges defined in two standards, however, reveal considerable differences in both the magnitude and phase. Greater differences are more evident for the

S. K. Patra; S. Rakheja; H. Nelisse; P.-É. Boileau; J. Boutin

2008-01-01

289

Active Magnetic Control of Oscillatory Axial Shaft Vibrations in Ship Shaft Transmission Systems Part 2: Control Analysis and Response of Experimental System  

Microsoft Academic Search

This is a companion paper to “ACTIVE MAGNETIC CONTROL OF OSCILLATORY AXIAL SHAFT VIBRATIONS IN SHIP SHAFT TRANSMISSION SYSTEMS—Part 1: System Natural Frequencies and Laboratory Scale Model.” Details of the modeling process were presented in that paper. In this work, the control analysis and some initial response results of the experimental system, which consists of a simulated fluid film thrust

David W. Lewis; Robert R. Humphris; Peter W. Thomas

1989-01-01

290

Response surface modeling of vibrating omega tube (Copper) electromechanical Coriolis mass flow sensor  

Microsoft Academic Search

Response Surface Methodology (RSM) is a combination of statistical and mathematical techniques to represent the relationship between the inputs and outputs of a physical system by explicit functions. This methodology has been widely employed in many applications such as design optimization, response prediction and model validation. But so far the literature related to its application in Coriolis mass flow sensing

Pravin P. Patil; Satish C. Sharma; Satish C. Jain

291

PVDF copolymer dust detectors: particle response and penetration characteristics  

NASA Astrophysics Data System (ADS)

Experiments using glass impactors with diameters in the range ~ 10-200 ?m and impact velocities in the range 0.9-14.4 km/s were carried out to measure the signal characteristics, velocity loss and degree of fragmentation for particles penetrating single and multiple polyvinylidene fluoride (PVDF) copolymer sensors with thicknesses 1.5-3.5 ?m. Pure PVDF sensors were also studied for comparison. Up to three sensors were placed in a time-of-flight (TOF) telescope arrangement which was followed by capture cell devices. The experimental results showed that PVDF copolymer sensors are xcellent dust detectors and have a response to dust impacts 30% higher than that of pure PVDF sensors. For impactors having velocities > 9 km/s and diameters s ~ 40 ?m, the particles vaporize upon single sensor penetration. For larger particles, ~ 50% are totally vaporized and ~ 50% provide TOF information but result in little or no debris in the capture cells. For impact velocities < 9.0 km/s, ~ 75% of the impactors suffer mild fragmentation, or no fragmentation, following single sensor penetration, with fractional velocity losses which range from < 0.5% for larger particles to ~ 15% for smaller particles. For impactors with diameter greater than ~ 10 times the sensor thickness, the diameter of the penetration hole in the sensor is less than 20% larger than the impactor diameter, and fragment spray angles of single and double sensor penetration are small (~ 2.5°) . The results for combined PVDF trajectory-capture cell systems established that, for ~ 75% of the impactors with velocities < ~ 8 km/s, thin sensor trajectory systems satisfy the requirements of velocity/trajectory determination, of identification of the location of particle fragments in capture cells, and of sufficient fragment mass following penetration of the trajectory sensors for successful capture and subsequent chemical and isotopic analysis.

Tuzzolino, A. J.

1992-06-01

292

Vibration study of the APS storage ring 0.8 meter quadrupole magnet/magnet support assembly  

SciTech Connect

The objectives of this study are as follows: Determine the vibration characteristics (frequency, damping, and mode shapes) of the magnet on prototypic supports (the actual mounting system used to mount the magnet on the girder). Measure system response to ambient floor motion. Measure the effect of various modifications to determine if the magnet response can be modified to minimize unwanted response characteristics. Modifications investigated include support schemes, increasing system damping, and increasing mechanical rigidity. Measure system response to coolant flow. Determine vibrational characteristics of a large concrete block placed on a concrete floor, including response to ambient floor motions.

Jendrzejczyk, J.A.; Wambsganss, M.W.; Smith, R.K.

1991-06-01

293

The genesis of torsional drillstring vibrations  

Microsoft Academic Search

Inherent drilling characteristics of polycrystalline diamond compact (PDC) bits alone can be sufficient to excite severe torsional drillstring vibrations. The work presented in this paper augments previous findings that torsional vibrations can result from the drilling characteristics of the bit itself. Laboratory and field torsional measurements are compared with model results to show that the observed vibrations can be explained

J. F. Brett

1992-01-01

294

Vibrational structure theory: new vibrational wave function methods for calculation of anharmonic vibrational energies and vibrational contributions to molecular properties.  

PubMed

A number of recently developed theoretical methods for the calculation of vibrational energies and wave functions are reviewed. Methods for constructing the appropriate quantum mechanical Hamilton operator are briefly described before reviewing a particular branch of theoretical methods for solving the nuclear Schrödinger equation. The main focus is on wave function methods using the vibrational self-consistent field (VSCF) as starting point, and includes vibrational configuration interaction (VCI), vibrational Møller-Plesset (VMP) theory, and vibrational coupled cluster (VCC) theory. The convergence of the different methods towards the full vibrational configuration interaction (FVCI) result is discussed. Finally, newly developed vibrational response methods for calculation of vibrational contributions to properties, energies, and transition probabilities are discussed. PMID:17551617

Christiansen, Ove

2007-03-23

295

Flexural rigidity of layers and its manifestation in the vibrational characteristics of strongly anisotropic layered crystals. Characteristic frequencies and stability conditions in quasi-two-dimensional systems  

NASA Astrophysics Data System (ADS)

The reasons for the appearance of flexural rigidity of layers in strongly anisotropic layered crystals are investigated. Structures consisting of loosely bound monatomic layers (specifically, graphite) as well as formed loosely bound structural elements each consisting of several monolayers which are coupled much more strongly with one another (for example, in dichalcogenide transition metals) are examined. The effect of the flexural rigidity on the phonon spectra of these compounds-quasi-flexural bending of the dispersion curves of phonon modes polarized in a direction normal to the layers-and the particularities appearing in the phonon densities of states as a result of quasi-flexural vibrational branches crossing low-frequency optical modes are analyzed.

Syrkin, E. S.; Feodos'ev, S. B.; Kravchenko, K. V.; Eremenko, A. V.; Kantor, B. Ya.; Kosevich, Yu. A.

2009-02-01

296

Effect of transport vibration levels on mechanical damage and physiological responses of Huanghua pears ( Pyrus pyrifolia Nakai, cv. Huanghua)  

Microsoft Academic Search

The effect of transport vibration on the quality of Huanghua pears (Pyrus pyrifolia Nakai, cv. Huanghua) during commercialization (room temperature) after transport was tested. Different vibration levels on the front and rear floors in a 2-tonne truck with leaf-spring suspensions were evaluated for their effect on mechanical damage to fruit during transport. Changes in color and cell membrane permeability of

Ran Zhou; Shuqiang Su; Liping Yan; Yunfei Li

2007-01-01

297

BENDING AND FORCED VIBRATION RESPONSE OF A CLAMPED ORTHOTROPIC THICK PLATE AND SANDWICH PANEL  

Microsoft Academic Search

A closed-form solution for the forced response of an orthotropic thick plate and sandwich panel has been developed and is presented in this paper. The paper outlines the methodology and develops the formulation to enable the solution to be derived. A novel truss-core sandwich panel is introduced and a method is outlined in which the panel is represented as an

T. S. LOK; Q. H. CHENG

2001-01-01

298

Bending and Forced Vibration Response of a Clamped Orthotropic Thick Plate and Sandwich Panel  

Microsoft Academic Search

A closed-form solution for the forced response of an orthotropic thick plate and sandwich panel has been developed and is presented in this paper. The paper outlines the methodology and develops the formulation to enable the solution to be derived. A novel truss-core sandwich panel is introduced and a method is outlined in which the panel is represented as an

T. S. Lok; Q. H. Cheng

2001-01-01

299

Noninvasive Determination of Bone Mechanical Properties using Vibration Response: A Refined Model and Validation in vivo.  

National Technical Information Service (NTIS)

Accurate non-invasive mechanical measurement of long bones is made difficult by the masking effect of surrounding soft tissues. Mechanical Response Tissue Analysis (MRTA) offers a method for separating the effects of the soft tissue and bone; however, a d...

S. G. Roberts T. M. Hutchinson S. B. Arnaud C. R. Steele B. J. Kiratli R. B. Martin

1996-01-01

300

Noninvasive Determination of Bone Mechanical Properties Using Vibration Response: A Refined Model and Validation in vivo.  

National Technical Information Service (NTIS)

Accurate non-invasive mechanical measurement of long bones is made difficult by the masking effect of surrounding soft tissues. Mechanical response tissue analysis (MRTA) offers a method for separating the effects of the soft tissue and bone; however, a d...

S. G. Roberts T. M. Hutchinson S. B. Arnaud B. J. Kiratli C. R. Steele

1996-01-01

301

Scanning LDV for Vibration Measurement of Filiform Hairs in Crickets in Response to Induced Airflow  

Microsoft Academic Search

Cercal hairs represent in cricket a wind sensitive escape system, able to detect the airflow generated from predating species. These sensors have been studied as a biomimetic concept to allow the development of MEMS for biomedical use. In particular, the behaviour of the hairs, including airflow response, resonant frequency and damping, has been investigated up to a frequency of 20

C. Santulli; T. J. Finn; R. Seidel; G. Jeronimidis

302

14 CFR 33.43 - Vibration test.  

Code of Federal Regulations, 2013 CFR

...vibration characteristics of the crankshaft and the propeller shaft or...shaft, over the range of crankshaft speed and engine power...vibration stresses of the crankshaft and the propeller shaft...sustained without fatigue failure and, for other shafts,...

2013-01-01

303

Ambient Vibration Survey of Newport Bridge.  

National Technical Information Service (NTIS)

The ambient vibration survey is a practical method of determining the dynamic properties of a structure. The characteristic mode shapes, their associated frequencies and the value of damping at low vibration levels are measured experimentally. The natural...

V. R. McLamore

1970-01-01

304

Ambient Vibration Survey of Chesapeake Bay Bridge.  

National Technical Information Service (NTIS)

The ambient vibration survey is a practical method of determining the dynamic properties of a structure. The characteristic mode shapes, their associated frequencies and the value of damping at low vibration levels are measured experimentally. The natural...

V. R. McLamore

1970-01-01

305

Structural and Machinery Vibrations of Hydrofoil Ships.  

National Technical Information Service (NTIS)

A study was made of the structural and machinery characteristics of several hydrofoil ships in order to determine parameters which are of main importance for vibration analyses. A preliminary hull vibration calculation of a hydrofoil ship was performed. I...

D. C. Robinson

1964-01-01

306

Yagi-Uda antenna with impedance vibrators  

Microsoft Academic Search

The solution of a problem of current distribution in Yagi-Uda antenna with impedance vibrators is represented. The influence of surface impedance of the vibrators on electrodynamical characteristics of considered structure has been investigated.

M. V. Nesterenko; V. A. Katrich; S. L. Berdnik; Y. M. Penkin

2010-01-01

307

String Vibrations  

NSDL National Science Digital Library

This site, by Andrew Davidhazy at the Rochester Institute of Technology, describes how to make interesting and artistic photographs of a vibrating string. Davidhazy explains how the string is vibrated, how the string is lit, and even the exposure time and the effect it has on the resulting image. Four images of the vibrating string are included.

2006-12-29

308

Verification of Vibration Characteristic of Hermetically Sealed Differential Floating Mass Transducer for Implantable Middle Ear Hearing Device Using Mock-Up of Ear  

Microsoft Academic Search

Several types of implantable middle ear hearing devices (IMEHDs) have been developed to overcome disadvantages of the conventional hearing aids. IMEHDs are divided into three parts which are a microphone, a signal processing unit, and a vibration transducer. In particular, the vibration transducer is very important component because it directly generates the mechanical vibration in the ossicles so that the

Min-Woo Kim; Ki-Woong Seong; Hyung-Gyu Lim; Eui-Sung Jung; Jang-Woo Lee; Dong-Wook Kim; Myoung-Won Lee; Ji-Hun Han; Jyung-Hyun Lee; Jin-Ho Cho

2008-01-01

309

An experimental study of changes in the impulse response of a wood plate that is subject to vibrational stimulus  

NASA Astrophysics Data System (ADS)

It is a well-known dictum among players of stringed instruments that the tone of a new instrument improves with playing and that a fine instrument needs to be played if it is to maintain its optimum sound quality. This process is sometimes referred to as ``playing in'' an instrument. There is scant mention in the scientific literature, however, of a quantitative analysis of this phenomenon. As a first step in rigorously testing this hypothesis, measurements were made of tap tones of rectangular pieces of thin spruce before and after they were subjected to vibrational stimulus. Four spruce rectangles (20x28 cm) were cut from a single sheet obtained from a luthier supplier; three of these were stimulated at different amplitudes, while the fourth was a control plate. The stimulus (provided by a harmonically driven guitar string connected to the plate via a bridge) lasted approximately 10 weeks, during which time tap tones of all four plates were periodically recorded. Spectrograms of the tap tones are compared among the plates and over time. A preliminary analysis of the data does not reveal any significant changes in the acoustic response of the plates.

Grogan, Jared; Braunstein, Michael; Piacsek, Andrew

2003-04-01

310

Stationary transducer response to planetary-gear vibration excitation with non-uniform planet loading  

Microsoft Academic Search

A relatively simple first-principles mathematical model of a generic planetary gear system is developed. System imperfections included are planet-to-planet variability in planet\\/ring-gear loading and generic ring-gear imperfections. General formulas for Fourier-series spectrum contributions of fixed-transducer responses to transmission-error vibratory excitations caused by planet\\/ring-gear tooth-meshing harmonics and ring-gear imperfections are derived, which include predicted effects caused by planet-to-planet variability in planet\\/ring-gear

W. D. Mark; J. A. Hines

2009-01-01

311

Damping and Forced Vibration Analyses of Viscoelastic Shells  

Microsoft Academic Search

The forced vibration response curves and damping characteristics of viscoelastic and sandwich viscoelastic shells are studied by a combination of the finite element and perturbation methods. The mathematical formulation is developed in a general form in order to take into account various viscoelastic models in the frequency domain. Frequency dependent Young modulus based on various Maxwell's model is used for

F. Abdoun; L. Azrar; E. M. Daya

2010-01-01

312

Damping phenomena in a wire rope vibration isolation system  

Microsoft Academic Search

A study is presented of the dynamic characteristics of a wire rope vibration isolation system constructed with helical isolators, with emphasis placed on the analytical modeling of damping mechanisms in the system. An experimental investigation is described in which the static stiffness curve, hysteresis curves, phase plane trajectories, and frequency response curves are obtained. A semiempirical model having nonlinear stiffness,

M. L. Tinker; M. A. Cutchins

1992-01-01

313

Damping phenomena in a wire rope vibration isolation system  

Microsoft Academic Search

A study of the dynamic characteristics of a wire rope vibration isolation system constructed with helical isolators is presented. Emphasis is placed on the analytical modeling of damping mechanisms in the system. An experimental investigation is described in which the static stiffness curve, hysteresis curves, phase trajectories, and frequency response curves were obtained. A semi-empirical model having nonlinear stiffness, nth-power

Michael L. Tinker; Malcolm A. Cutchins

1990-01-01

314

Stationary transducer response to planetary-gear vibration excitation with non-uniform planet loading  

NASA Astrophysics Data System (ADS)

A relatively simple first-principles mathematical model of a generic planetary gear system is developed. System imperfections included are planet-to-planet variability in planet/ring-gear loading and generic ring-gear imperfections. General formulas for Fourier-series spectrum contributions of fixed-transducer responses to transmission-error vibratory excitations caused by planet/ring-gear tooth-meshing harmonics and ring-gear imperfections are derived, which include predicted effects caused by planet-to-planet variability in planet/ring-gear loading. Good approximations to the coefficient of variation of planet loading (CVPL) are shown to be readily obtainable from measured planet-carrier rotational-harmonic spectra obtained by fixed transducers. The predicted spectrum behavior is compared with fixed-accelerometer response spectra measured from UH-60A planetary systems without and with planet-loading variability caused by a cracked planet-carrier plate. The main features of predicted and measured spectra are in good agreement.

Mark, W. D.; Hines, J. A.

2009-05-01

315

Ab initio determination of geometries and vibrational characteristics of building blocks of organic super-conductors: TTF and its derivatives.  

PubMed

Molecular behavior of the building block {[2-(1,3-dithiole-2-ylidene)-1,3-dithiole] ? tetrathiafulvalene (TTF)} of organic superconductors have been investigated along with its three derivatives, namely, {[2-(1,3-dioxole-2-ylidene)-1,3-dioxole] ? tetraoxafulvalene (TOF)}; [2,2]-bi -[[1,3] oxathiolylidene] ? Der I and 2-(3H-Furan-2-ylidene)-[1,3] oxathiole ? Der II. The properties of the molecules such as molecular geometries, frontier MOs and vibrational spectra have been investigated by using DFT method at the B3LYP level employing 6-311++G(d,p) basis set. The geometrical parameters and atomic charges on various atomic sites of the TTF, TOF, Ders I and II suggest extended conjugation in these systems. The present calculations lead to the reassignments for of some of the fundamentals and new interpretations for some of the observed IR and Raman frequencies. One of the two modes involved in the Fermi resonance giving rise to the doublet 1555 and 1564 cm(-1) needed to be revised and another doublet 3083 and 3108 cm(-1) could be interpreted as a Fermi resonance doublet. Out of the two ?(C = C) modes under the a(1) species, the lower frequency mode is assigned to the ?(C = C) of the ring and the higher one to the ?(C = C) of the central C = C bond contrary to the assignment reported in literature. The conducting properties of these molecules depend mainly on this mode. PMID:23040970

Rani, P; Yadav, R A

2012-08-02

316

Victim and Crime Characteristics, Coping Responses, and Short and Long-Term Recovery From Victimization  

Microsoft Academic Search

The victims of five crime types were contrasted on victim characteristics, crime characteristics, and coping responses to the crime and on four measures of 1- and 6-month psychological distress. Significant sociodemographic and coping response differences were found between victims of different crime types. Changing telephone numbers and staying home more were associated with significantly higher levels of 1- and 6-month

Philip W. Wirtz; Adele V. Harrell

1987-01-01

317

Gender and response effects in telephone interviews about gender characteristics  

Microsoft Academic Search

This study investigates the effect of gender on responses to questions about sex role orientations. Literature on gender effects in survey interviews, job interviews and counseling studies, and experiments leads to hypotheses that male interviewers will elicit more response effects than female interviewers, especially from females; that female respondents will show desirability effects more than males; and that respondents, especially

Lloyd B. Lueptow; Susan L. Moser; Brian F. Pendleton

1990-01-01

318

Responsibility attitudes and interpretations are characteristic of obsessive compulsive disorder  

Microsoft Academic Search

The cognitive–behavioural theory of Obsessive Compulsive Disorder (OCD) proposes that a key factor influencing obsessional behaviour is the way in which the intrusive cognitions are interpreted. The present paper reports an investigation of links between clinical symptoms (of anxiety, depression and obsessionality) and responsibility beliefs. These beliefs include not only measures of general responsibility attitudes (assumptions) but also more specific

P. M. Salkovskis; A. L. Wroe; A. Gledhill; N. Morrison; E. Forrester; C. Richards; M Reynolds; S Thorpe

2000-01-01

319

Magnetoelastic vibrational biomaterials for real-time monitoring and modulation of the host response.  

PubMed

Magnetoelastic (ME) biomaterials are ferromagnetic materials that physically deform when exposed to a magnetic field. This work describes the real-time control and monitoring capabilities of ME biomaterials in wound healing. Studies were conducted to demonstrate the capacity of the materials to monitor changes in protein adsorption and matrix stiffness. In vitro experiments demonstrated that ME biomaterials can monitor cell adhesion and growth in real-time, and a long-term in vivo study demonstrated their ability to monitor the host response (wound healing) to an implant and control local cell density and collagen matrix production at the soft tissue-implant interface. This approach represents a potentially self-aware and post-deployment activated biomaterial coating as a means to monitor an implant surface and provide an adjuvant therapy for implant fibrosis. PMID:23354739

Vlaisavljevich, E; Holmes, H R; Tan, E L; Qian, Z; Trierweiler, S; Ong, K G; Rajachar, R M

2013-01-26

320

Cosine response characteristics of radiometric and photometric sensors  

SciTech Connect

Global and diffuse irradiance and illuminance are measured with instruments that are assumed to have true cosine responses. It is known, largely from reports with a limited distribution or by word of mouth, that no instrument is perfect in this regard. This paper reports on measurements of cosine responses for several instrument types and manufacture familiar to the solar radiation measurement community. The measurements were made with an automated cosine response test bench using the same protocol for each instrument. The cosine bench measures with variable angular resolution as fine as 0.25 degrees. The automated rotation is in one plane. A manual rotation allows measurements for other azimuths. 6 refs.

Michalsky, J.J.; Harrison, L.C.; Berkheiser, W.E. III

1992-05-01

321

Cosine response characteristics of radiometric and photometric sensors  

SciTech Connect

Global and diffuse irradiance and illuminance are measured with instruments that are assumed to have true cosine responses. It is known, largely from reports with a limited distribution or by word of mouth, that no instrument is perfect in this regard. This paper reports on measurements of cosine responses for several instrument types and manufacture familiar to the solar radiation measurement community. The measurements were made with an automated cosine response test bench using the same protocol for each instrument. The cosine bench measures with variable angular resolution as fine as 0.25 degrees. The automated rotation is in one plane. A manual rotation allows measurements for other azimuths. 6 refs.

Michalsky, J.J.; Harrison, L.C.; Berkheiser, W.E. III.

1992-01-01

322

Estimating residual stress, curvature and boundary compliance of doubly clamped MEMS from their vibration response  

NASA Astrophysics Data System (ADS)

Structural parameters of doubly clamped microfabricated beams such as initial curvature, boundary compliance, thickness and mean residual stress are often critical to the performance of microelectromechanical systems (MEMS) and need to be estimated as a part of quality control of the microfabrication process. However, these parameters couple and influence many metrics of device response and thus are very difficult to disentangle and estimate using conventional methods such as the M-test, static mechanical tests, pull-in measurements or dynamic mechanical tests. Here we present a simple, non-destructive experimental method to extract these parameters based on the non-contact measurement of the natural frequencies of the lowest few eigenmodes of the microfabricated beam, and knowledge of Young's modulus and plan dimensions of the beam alone. The method exploits the fact that certain eigenmodes are insensitive to some of these structural parameters which enable a convenient decoupling and estimation of the parameters. As a result, the method does not require complicated finite element analysis, is insensitive to the gap height and introduces no contact wear or dielectric charging effects. Experiments are performed using laser Doppler vibrometry to measure the natural frequencies of doubly clamped, nickel, RF-MEMS capacitive switches and the method is applied to extract the residual stress, beam thickness, boundary compliance and post-release curvature.

Tung, Ryan C.; Garg, Anurag; Kovacs, Andrew; Peroulis, Dimitrios; Raman, Arvind

2013-04-01

323

Proteomics characteristics of rice leaves in response to environmental factors  

Microsoft Academic Search

Rice is an important food crop worldwide. Its productivity has been influenced by various abiotic and biotic factors including\\u000a temperature, drought, salt, microbe, ozone, hormone and glyphosate. The responses of plants to stress are regulated by multiple\\u000a signaling pathways, and the mechanisms of leaf growth and development in response to stress remain unclear to date. Recently,\\u000a proteomics studies have provided

Sining Kang; Sixue Chen; Shaojun Dai

2010-01-01

324

MYOELECTRIC RESPONSE OF BACK MUSCLES TO VERTICAL RANDOM WHOLE-BODY VIBRATION WITH DIFFERENT MAGNITUDES AT DIFFERENT POSTURES  

Microsoft Academic Search

Back muscle forces contribute essentially to the whole-body vibration-induced spinal load. The electromyogram (EMG) can help to estimate these forces during whole-body vibration (WBV). Thirty-eight subjects were exposed to identical random low-frequency WBV (0·7, 1·0 and 1·4 m\\/s-2 r.m.s. weighted acceleration) at a relaxed, erect and bent forward postures. The acceleration of the seat and the force between the seat

R. Blüthner; H. Seidel; B. Hinz

2002-01-01

325

Ocular Vestibular Evoked Myogenic Potentials in Response to Bone-Conducted Vibration of the Midline Forehead at Fz  

Microsoft Academic Search

If a patient, who is lying supine and looking upward, is given bone-conducted vibration (BCV) of the forehead at the hairline in the midline (Fz) with a clinical reflex hammer or a powerful bone conduction vibrator, short-latency surface potentials called ocular vestibular evoked myogenic potentials (oVEMP) can be recorded from just beneath the eyes. The early negative (excitatory) component (n10)

S. Iwasaki; Y. E. Smulders; A. M. Burgess; L. A. McGarvie; H. G. MacDougall; G. M. Halmagyi; I. S. Curthoys

2008-01-01

326

Genetically engineered protein in hydrogels tailors stimuli-responsive characteristics  

NASA Astrophysics Data System (ADS)

Certain proteins undergo a substantial conformational change in response to a given stimulus. This conformational change can manifest in different manners and result in an actuation, that is, catalytic or signalling event, movement, interaction with other proteins, and so on. In all cases, the sensing-actuation process of proteins is initiated by a recognition event that translates into a mechanical action. Thus, proteins are ideal components for designing new nanomaterials that are intelligent and can perform desired mechanical actions in response to target stimuli. A number of approaches have been undertaken to mimic nature's sensing-actuating process. We now report a new hybrid material that integrates genetically engineered proteins within hydrogels capable of producing a stimulus-responsive action mechanism. The mechanical effect is a result of an induced conformational change and binding affinities of the protein in response to a stimulus. The stimuli-responsive hydrogel exhibits three specific swelling stages in response to various ligands offering additional fine-tuned control over a conventional two-stage swelling hydrogel. The newly prepared material was used in the sensing, and subsequent gating and transport of biomolecules across a polymer network, demonstrating its potential application in microfluidics and miniaturized drug-delivery systems.

Ehrick, Jason D.; Deo, Sapna K.; Browning, Tyler W.; Bachas, Leonidas G.; Madou, Marc J.; Daunert, Sylvia

2005-04-01

327

A study of vibration and vibration control of ship structures  

Microsoft Academic Search

This paper examines the vibration characteristics and vibration control of complex ship structures. It is shown that input mobilities of a ship structure at engine supports, due to out-of-plane force or bending moment excitations, are governed by the flexural stiffness of the engine supports. The frequency averaged input mobilities of the ship structure, due to such excitations, can be represented

Tian Ran Lin; Jie Pan; Peter J. O'Shea; Chris K. Mechefske

2009-01-01

328

PVDF copolymer dust detectors: particle response and penetration characteristics  

Microsoft Academic Search

Experiments using glass impactors with diameters in the range ~ 10-200 mum and impact velocities in the range 0.9-14.4 km\\/s were carried out to measure the signal characteristics, velocity loss and degree of fragmentation for particles penetrating single and multiple polyvinylidene fluoride (PVDF) copolymer sensors with thicknesses 1.5-3.5 mum. Pure PVDF sensors were also studied for comparison. Up to three

A. J. Tuzzolino

1992-01-01

329

Frequency response characteristics of the fuzzy polar power system stabilizer  

SciTech Connect

The fuzzy polar power system stabilizer (FPPSS) which has been recently developed is analyzed using frequency domain methods. the frequency domain approach allows the PSS designer to compare the new FPPSS with more conventional controllers. The significance of the three FPPSS design parameters are readily seen from the frequency response data, and their relationship to the conventional lead-lag design approach can be evaluated. Furthermore, the frequency response data for the FPPSS allows an alternate design approach for this stabilizer, and can be used to develop information concerning the small signal stability of the resulting system.

Ortmeyer, T.H. [Clarkson Univ., Potsdam, NY (United States). Electrical and Computer Engineering Dept.; Hiyama, Takashi [Kumamoto Univ. (Japan). Dept. of Electrical Engineering and Computer Science

1995-06-01

330

PREFACE: Vibrations at surfaces Vibrations at surfaces  

NASA Astrophysics Data System (ADS)

This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of Central Florida, Orlando, in March 2010. Several speakers at this meeting were invited to contribute to the special section in this issue. As is clear from the articles in this special section, the phenomenon of vibrations at surfaces continues to be a dynamic field of investigation. In fact, there is a resurgence of effort because the insights provided by surface dynamics are still fundamental to the development of an understanding of the microscopic factors that control surface structure formation, diffusion, reaction and structural stability. Examination of dynamics at surfaces thus complements and supplements the wealth of information that is obtained from real-space techniques such as scanning tunneling microscopy. Vibrational dynamics is, of course, not limited to surfaces. Surfaces are important since they provide immediate deviation from the bulk. They display how lack of symmetry can lead to new structures, new local atomic environments and new types of dynamical modes. Nanoparticles, large molecules and nanostructures of all types, in all kinds of local environments, provide further examples of regions of reduced symmetry and coordination, and hence display characteristic vibrational modes. Given the tremendous advance in the synthesis of a variety of nanostructures whose functionalization would pave the way for nanotechnology, there is even greater need to engage in experimental and theoretical techniques that help extract their vibrational dynamics. Such knowledge would enable a more complete understanding and characterization of these nanoscale systems than would otherwise be the case. The papers presented here provide excellent examples of the kind of information that is revealed by vibrations at surfaces. Vibrations at surface contents Poisoning and non-poisoning oxygen on Cu(410)L Vattuone, V Venugopal, T Kravchuk, M Smerieri, L Savio and M Rocca Modifying protein adsorption by layers of glutathione pre-adsorbed on Au(111)Anne Vallée, Vincent Humblot, Christophe Méthivier, Paul Dumas and Claire-Marie Pradier Relating temperature dependence of atom

Rahman, Talat S.

2011-12-01

331

Nonlinear vibrational resonance  

NASA Astrophysics Data System (ADS)

We examine the nonlinear response of a bistable system driven by a high-frequency force to a low-frequency weak field. It is shown that the rapidly varying temporal oscillation breaks the spatial symmetry of the centrosymmetric potential. This gives rise to a finite nonzero response at the second harmonic of the low-frequency field, which can be optimized by an appropriate choice of vibrational amplitude of the high-frequency field close to that for the linear response. The potential implications of the nonlinear vibrational resonance are analyzed.

Ghosh, Shyamolina; Ray, Deb Shankar

2013-10-01

332

Characteristic Neurobiological Patterns Differentiate Paternal Responsiveness in Two Peromyscus Species  

Microsoft Academic Search

Rodent paternal models provide unique opportunities to investigate the emergence of affiliative social behavior in mammals. Using biparental and uniparental Peromyscus species (californicus and maniculatus, respectively) we assessed paternal responsiveness by exposing males to biological offspring, unrelated conspecific pups, or familiar brothers following a 24-hour separation. The putative paternal circuit we investigated included brain areas involved in fear\\/anxiety [cingulate cortex

Kelly G. Lambert; Catherine L. Franssen; Massimo Bardi; Joseph E. Hampton; Leslie Hainley; Stephanie Karsner; Eddie B. Tu; Molly M. Hyer; Ashly Crockett; Anya Baranova; Tajh Ferguson; Tenaj Ferguson; Craig H. Kinsley

2011-01-01

333

Lapses of responsiveness: Characteristics, detection, and underlying mechanisms.  

PubMed

Lapses in responsiveness ('lapses'), particularly microsleeps and attention lapses, are complete disruptions in performance from approximately 0.5-15 s. They are of particular importance in the transport sector in which there is a need to maintain sustained attention for extended periods and in which lapses can lead to multiple-fatality accidents. PMID:21095933

Jones, Richard D; Poudel, Govinda R; Innes, Carrie R H; Davidson, Paul R; Peiris, Malik T R; Malla, Amol M; Signal, T; Carroll, Grant J; Watts, Richard; Bones, Philip J

2010-01-01

334

Intra- and inter-molecular hydrogen bonds, conformation and vibrational characteristics of hydrazo-group in 5-nitro-2-(2-phenylhydrazinyl)pyridine and its 3-, 4- or 6-methyl isomers.  

PubMed

Syntheses of 5-nitro-2-(2-phenylhydrazinyl)pyridine (5-nitro-2-phenylhydrazopyridine), 3-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (3-methyl-5-nitro-2-phenylhydrazopyridine), 4-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (4-methyl-5-nitro-2-phenylhydrazopyridine) and 6-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (6-methyl-5-nitro-2-phenylhydrazopyridine) have been described. Their IR and Raman spectra have been measured and analyzed in terms of DFT quantum chemical calculations. The 6-311G(2d,2p) basis set with the B3LYP functional has been used to discuss the optimized structure and vibrational spectra. The vibrational characteristics of the hydrazo-bond have been reported with their relation to the inter- and intra-molecular hydrogen bonds formed in the studied systems. The role and influence of substitution position of the methyl chromophore on the structure and vibrational data have been discussed. PMID:23680510

Michalski, J; Kucharska, E; S?siadek, W; Lorenc, J; Hanuza, J

2013-04-19

335

Intra- and inter-molecular hydrogen bonds, conformation and vibrational characteristics of hydrazo-group in 5-nitro-2-(2-phenylhydrazinyl)pyridine and its 3-, 4- or 6-methyl isomers  

NASA Astrophysics Data System (ADS)

Syntheses of 5-nitro-2-(2-phenylhydrazinyl)pyridine (5-nitro-2-phenylhydrazopyridine), 3-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (3-methyl-5-nitro-2-phenylhydrazopyridine), 4-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (4-methyl-5-nitro-2-phenylhydrazopyridine) and 6-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (6-methyl-5-nitro-2-phenylhydrazopyridine) have been described. Their IR and Raman spectra have been measured and analyzed in terms of DFT quantum chemical calculations. The 6-311G(2d,2p) basis set with the B3LYP functional has been used to discuss the optimized structure and vibrational spectra. The vibrational characteristics of the hydrazo-bond have been reported with their relation to the inter- and intra-molecular hydrogen bonds formed in the studied systems. The role and influence of substitution position of the methyl chromophore on the structure and vibrational data have been discussed.

Michalski, J.; Kucharska, E.; S?siadek, W.; Lorenc, J.; Hanuza, J.

2013-08-01

336

Wind response characteristics of horizontal axis wind turbines  

NASA Astrophysics Data System (ADS)

It was the objective of the work reported here, and in the companion paper 1 . A broader examination of wind turbine dynamic response to turbulence, and attempts to ascertain the features of turbulence that wind turbines are most sensitive to were made. A statistical description of the wind input including all three wind components and allowing linear wind gradients across the rotor disk, was used together with quasi-static aerodynamic theory and an elementary structural model involving only a few degrees of freedom. The idea was to keep the turbine model simple and show the benefits of this type of statistical wind representation before attempting to use a more complex turbine model. As far as possible, the analysis was kept in the simplest form, while still preserving key physical responses.

Thresher, R. W.; Holley, W. E.; Jafarey, N.

1981-05-01

337

[Effect of baclofen on characteristics of the cellular immune response].  

PubMed

It has been established that GABA-B receptor agonist baclofen restores the cellular parts (the delay-type hypersensitivity reaction index, thymus weight, and thymocyte number) of immunogenesis under the experimental suppression conditions. This is probably caused both by the direct influence of baclofen on the receptors of immunocompetent cells and by the normalization of the nervous regulation of the immune response. PMID:18652257

Tiurenkov, I N; Samotrueva, M A; Ovcharova, A N

338

Operational Characteristics of an Automated Intrusion Response System  

Microsoft Academic Search

\\u000a Continuing organisational dependence upon computing and networked systems, in conjunction with the mounting problems of security\\u000a breaches and attacks, has served to make intrusion detection systems an increasingly common, and even essential, security\\u000a countermeasure. However, whereas detection technologies have received extensive research focus for over fifteen years, the\\u000a issue of intrusion response has received relatively little attention – particularly in

Maria Papadaki; Steven Furnell; Benn Lines; Paul L. Reynolds

2003-01-01

339

Free vibration of two identical circular cylinders in staggered arrangement  

NASA Astrophysics Data System (ADS)

An investigation on flow-induced response characteristics of two identical circular cylinders in staggered arrangement is conducted in the fluid mechanics laboratory of Kitami Institute of Technology, Japan. Each cylinder was two-dimensional, spring mounted, and allowed to vibrate independently in the cross-flow direction. Measurements were conducted at stagger angle ? = 5°, 10°, 15°, 25°, 45° and 60°, L/D ranging from 0.1 to 3.2, with ?L/D = 0.1, where L is the gap width between the cylinders, and D is the diameter of a cylinder. At each position (?, L/D) of the cylinders, dependence of vibration-amplitude-to-diameter ratio a/D on reduced velocity Ur (= U?/(fnD)) is examined, where U? is the free-stream velocity and fn is the natural frequency of the cylinder. There are seven cylinder-response patterns, depending on whether vortex-excited and/or galloping vibrations of the cylinders are generated, in the range ? = 5°-60°, L/D = 0.1-3.2 and Ur = 1.5-26. Pattern I corresponds to no generation of vortex-excited or galloping vibration of either cylinder. In Pattern II the upstream cylinder does not experience vortex-excited or galloping vibration, but the downstream one experiences a galloping vibration. Pattern III involves both vortex-excited and galloping vibrations of the downstream cylinder and only galloping vibration of the upstream cylinder. Pattern IV is associated with generation of vortex-excited vibration of both cylinders at the same Ur range. Pattern V refers to the case where the downstream cylinder experiences vortex-excited vibration, but the upstream cylinder does not. Pattern VI is characterized by vortex-excited vibration of the downstream cylinder in two regimes of Ur, whereas that of the upstream cylinder occurs in one regime only. In Pattern VII the upstream and downstream cylinders experience vortex-excited vibration at two different Ur regimes, respectively. The L/D regime of the vibration patterns generated at each ? is identified.

Mahbub Alam, Md; Kim, Sangil

2009-06-01

340

TECHNICAL NOTE: A piezostack-based active mount for broadband frequency vibration control: experimental validation  

NASA Astrophysics Data System (ADS)

This paper presents an experimental investigation on vibration control using an active mount activated by piezostack actuators. After describing the schematic configuration and operational principle of the proposed active mount, dynamic characteristics of the rubber element and the piezostack are experimentally identified. An active mount is then manufactured using a rubber element and two piezostack elements. Prior to validating vibration control of the proposed active mount, fundamental characteristics such as resonant frequency, deflection at rated load, strength, shock and fatigue characteristics are experimentally investigated. A two-degree-of-freedom control system in which an active mount is installed with a supported mass of 100 kg is established for evaluating vibration control performance. In order to actively attenuate the vibration transmitted from the base excitation (50-1000 Hz), a negative velocity feedback controller is experimentally realized. Control responses such as mass acceleration are evaluated in both frequency and time domains.

Choi, Seung-Bok; Sohn, Jung Woo; Choi, Sang-Min; Nguyen, Vien Quoc; Moon, Seok-Jun

2009-09-01

341

Nonlinear Response and Failure Characteristics of Internally Pressurized Composite Cylindrical Panels.  

National Technical Information Service (NTIS)

Results of an experimental and analytical study of the nonlinear response and failure characteristics of internally pressurized 4- to 16-ply-thick graphite-epoxy cylindrical panels are presented. Specimens with clamped boundaries simulating the skin betwe...

R. L. Boitnott E. R. Johnson J. H. Starnes

1985-01-01

342

Responses to Mild Cold Stress Are Predicted by Different Individual Characteristics in Young and Older Subjects  

NSDL National Science Digital Library

Journal article "Responses to Mild Cold Stress Are Predicted by Different Individual Characteristics in Young and Older Subjects", from the Journal of Applied Physiology, by David W. Degroot, W. Larry Kenny, and George Havenith.

David W DeGroot (Pennsylvania State University Kinesiology); Larry W. Kenny (Pennsylvania State University Kinesiology); George Havenith (Loughborough University Human Sciences)

2006-12-01

343

Vibrational drives for precision instruments  

SciTech Connect

The principles underlying the construction of vibrational drives for precision systems are described. The main characteristics of the drives in the asynchronous and synchronous regimes of motion are presented along with their technical specifications.

Kurilo, R.E.; Syanyunas, G.I.

1994-12-01

344

Mated Vertical Ground Vibration Test.  

National Technical Information Service (NTIS)

The Mated Vertical Ground Vibration Test (MVGVT) was considered to provide an experimental base in the form of structural dynamic characteristics for the shuttle vehicle. This data base was used in developing high confidence analytical models for the pred...

E. W. Ivey

1980-01-01

345

'Nordic' hamstrings exercise - engagement characteristics and training responses.  

PubMed

The present study examined the neuromuscular activation characteristics of the hamstrings during the 'Nordic' hamstrings exercise (NHE) and changes in the eccentric strength of the knee flexors with NHE training. Initially, the normalised root mean square electromyographic (EMG) activity of the hamstrings of both limbs during various phases (90-61°, 60-31° and 30-0° of knee extension) of the NHE were determined in 18 soccer players. Subsequently participants were randomly allocated to either a training (n=10) or control group. The isokinetic eccentric peak torques of the dominant and non-dominant limbs were recorded at 60, 120 and 240°/s pre- and post-training. The EMG values of both limbs were comparable (P=0.184) and greater EMG activity was recorded at more extended knee positions of the NHE (P=0.001). 4 weeks of NHE training significantly improved peak torque by up to 21% in all assessment conditions. Data indicate the hamstrings of both limbs are engaged identically during the NHE and training results in gains in the eccentric peak torque of the hamstrings of both limbs; these gains may augment the force that the hamstrings can withstand when forcefully stretched, attenuating injury risk. PMID:22895870

Iga, J; Fruer, C S; Deighan, M; Croix, M D S; James, D V B

2012-08-15

346

Characteristics of antibody responses in Pigeon Fanciers' Lung.  

PubMed

The aetiology of Pigeon Fanciers' Lung (PFL) is believed to include immune complex formation between inhaled pigeon antigens and antibodies generated against them. However it is unclear why some fanciers are asymptomatic despite the presence of high levels of anti-avian antigen antibodies in their serum. In this study we investigated whether qualitative differences in specific antibodies might contribute to disease. IgG responses among pigeon fanciers were determined by ELISA and the functional affinity of IgG1 and IgG2 against a range of pigeon antigens was determined by inhibition ELISA and Isothermal Titration Calorimetry (ITC). The median titres of IgG1 and IgG2 against all the pigeon antigens tested was higher in asymptomatic than symptomatic fanciers and these differences were significant for anti-pigeon serum IgG1 (P=0.04), anti-fresh pigeon droppings (PDF) IgG2 (P=0.028), anti-old pigeon droppings (PDO) IgG2 (P=0.04) and anti-pigeon intestinal scrapings IgG2 (P=0.03). The functional affinity of IgG1 and IgG2 against PDO was higher in symptomatic individuals (P=0.006 and P=0.002, respectively) whilst the functional affinity of anti-PDF IgG2 was also significantly higher in these patients (P?0.001). Symptomatic fanciers were also significantly more likely to have a high reaction enthalphy (?H) as measured by ITC and thus had higher affinity antibodies against PDO (P=0.044). This data confirms previous studies showing that the magnitude alone of the antibody response to pigeon antigens cannot determine the presence of PFL, but that antibody affinity may be important. ITC is a rapid method of measuring antibody affinity and has diagnostic potential in PFL, and may be of use in other situations where antibody affinity is important. PMID:23291145

Nademi, Zohreh; Todryk, Stephen; Baldwin, Christopher

2013-01-04

347

Determination of the global responses characteristics of a piecewise smooth dynamical system with contact  

Microsoft Academic Search

In this paper the global response characteristics of a piecewise smooth dynamical system with contact, which is specifically\\u000a used to describe the rotor\\/stator rubbing systems, is studied analytically. A method to derive the global response characteristics\\u000a of the model is proposed by studying each piece of the equations corresponding to different phases of the rotor motion, i.e.,\\u000a the phase without rubbing,

Jun Jiang

2009-01-01

348

Dynamic and subjective responses of seated subjects exposed to simultaneous vertical and fore-and-aft whole-body vibration: The effect of the phase between the two single-axis components  

NASA Astrophysics Data System (ADS)

Subjective and dynamic responses of seated subjects exposed to simultaneous vertical and fore-and-aft sinusoidal whole-body vibration were investigated. The effect of the phase difference between the vertical and the fore-and-aft vibration on the responses was of a particular interest in this study. Fifteen subjects were exposed to dual-axis vibrations at six frequencies (2.5 8 Hz) and at eight phases between the two single-axis components (0 315°). The magnitude of vibration in each axis was constant at 0.7 m s-2 rms. Discomfort caused by vibration was measured by the method of magnitude estimation. The motion of the body were measured at the head and three locations along the spine with accelerometers attached to the body surface. The most significant effect of the phase between the two single-axis components on the discomfort was observed at 5 Hz: about 40% difference in the median discomfort estimate caused by changing the phase. The transmissibilities from vertical seat vibration to vertical motions of the spine varied from 0.5 to 2.0 by changing the phase between the two single-axis components at frequencies from 2.5 to 5 Hz. The effect of the phase observed in the dynamic response was not predicted by the superposition of the responses to each single-axis vibration. The discomfort caused by the dual-axis vibration tended to be correlated better with the combinations of the dynamic responses measured in the two axes than with the dynamic responses in a single axis.

Matsumoto, Yasunao; Ohdo, Katsutoshi; Saito, Tetsuro

2006-12-01

349

Response Characteristics of Scirpus Triqueter and Its Rhizosphere to Pyrene Contaminated Soils at Different Growth Stages  

Microsoft Academic Search

Scirpus triqueter (Triangular club-rush), a typical wetland species, is used to study the response characteristics to pyrene. A pot experiment was conducted to investigate the growth parameters (height, diameter, shoot number, total volume, underground biomass, aboveground biomass and total biomass), and enzymes (catalase and superoxide dismutase) of S. triqueter. The characteristics of soil enzymes (catalase and polyphenol oxidase) and microorganisms

X. Y. Zhang; X. Y. Liu; S. S. Liu; F. H. Liu; L. S. Chen; G. Xu; C. L. Zhong; P. C. Su; Z. N. Cao

2012-01-01

350

Response characteristics of Scirpus triqueter and its rhizosphere to pyrene contaminated soils at different growth stages  

Microsoft Academic Search

Scirpus triqueter (Triangular club-rush), a typical wetland species, is used to study the response characteristics to pyrene. A pot experiment was conducted to investigate the growth parameters (height, diameter, shoot number, total volume, underground biomass, aboveground biomass and total biomass), and enzymes (catalase and superoxide dismutase) of S. triqueter. The characteristics of soil enzymes (catalase and polyphenol oxidase) and microorganisms

X. Y. Zhang; X. Y. Liu; S. S. Liu; F. H. Liu; L. H. Chen; G. Xu; C. L. Zhong; P. C. Su; Z. N. Cao

2011-01-01

351

An estimation of load characteristics of an ultrasonic motor by measuring transient responses  

Microsoft Academic Search

To measure the characteristics of ultrasonic motors, such as the maximum torque, torque-speed relationship and the frictional coefficient at the contact surface, a method in which the torque is calculated from the transient responses is proposed. The rise curve that is the transitional change in the rotor speed soon after turning on the motor gives the load characteristics, while the

Kentaro Nakamura; Minoru Kurosawa; Hisayuki Kurebayashi; Sadayuki Ueha

1991-01-01

352

Plant characteristic estimation using sonar, multispectral reflectance, and electromagnetic response  

NASA Astrophysics Data System (ADS)

Scope and method of study. The goal of this study was to design, test and validate three methods of remotely estimating plant physical and physiological characteristics. A free-space parallel plate electrostatic sensing system operating at medium radio frequency range was used to estimate water content and plant dry biomass. An ultrasound distance sensing system and a multispectral imaging system was used to directly estimate plant height and top view surface area and indirectly estimate plant biomass. NDVI was calculated from the multispectral imaging system data. Combining NDVI with the plant height and top view surface area estimates, a correlation was observed between plant biomass, chlorophyll content and chlorophyll concentration. Findings and conclusions. Plant water content and dry biomass of greenhouse grown spinach were estimated using a free-space electrostatic sensing system (r2 = 0.95). Ultrasonic sensor-based height estimates and top view surface area multispectral image data provided plant biomass estimates in corn and spinach (r 2 = 0.85 and 0.88). Estimates for snap beans were not as convincing (r2 = 0.52). Combining biomass estimates from the height and surface area data obtained by the ultrasonic distance sensor and the multispectral imaging system with NDVI670 calculated from reflectance data from the imaging system provided strong correlations with chlorophyll content in spinach (r 2 = 0.91). This was an improvement from the chlorophyll content estimates using only NDVI670. Correlations with chlorophyll concentration were weak. The strongest correlation was found using the reflectance ratio, NIR/Green (r2 = 0.30).

Jones, Carol L.

353

Drill collar length is a major factor in vibration control  

Microsoft Academic Search

Drill collar length directly affects the overall vibration response of drill strings. Drill collar length is partly responsible for severe vibrations in hard rock drilling but can also be the solution to vibration control. This paper gives a new interpretation to the cause and control of drill string vibrations and presents the results in terms of formulas that can be

Dareing

1982-01-01

354

Plant growth in controlled environments in response to characteristics of nutrient solutions  

SciTech Connect

Plant growth in controlled environments in response to characteristics of nutrient solutions is discussed. Descriptions of experimental results concerning root acclimation to temperature, root and shoot acclimation to nitrogen stress, and growth response to NH4(+) and NO3(-) nutrition are included. A preliminary model validation to changing temperatures is presented.

Raper, C.D. Jr.

1982-11-01

355

Biometrical characteristics and physiological responses to a local cold exposure of the extremities  

Microsoft Academic Search

The aim of this study was firstly to describe the physiological responses observed in 19 subjects during immersion of the arm up to the elbow in water at 5 °C (5 min) followed by a 10-min recovery and secondly, to correlate the observed physiological responses with biometrical characteristics of the subjects (maximal oxygen uptake, VO2max, percentage fat content of whole

Gustave Savourey; Isabelle Sendowski; Jacques Bittel

1996-01-01

356

The Effects of Job Characteristics and Gender On Hourly Employees' Personal Responsibility  

Microsoft Academic Search

This study investigated the impact of several job characteristics on the sense of personal responsibility experienced by male and female assembly line employees. Role clarity, task identity, freedom, and task significance all affected women's perceptions that they were responsible for their work, and role clarity and task identity affected men's perceptions. The results suggested that the patterns by which job

Jean M. Bartunek

1986-01-01

357

Vibrational modes of the pedestal support system for the SLC Arc magnets  

SciTech Connect

The magnet support system for the SLC Arcs will be a long series of pedestals with each pedestal supporting the ends of two adjacent magnets. It has been pointed out by several authors that random magnet vibrations in the Arc with amplitudes larger than 0.1 ..mu..m rms are potentially harmful for the SLC operation. In order to assess the vibrational behavior of the Arc magnet system, we need to understand: (1) the sources and characteristics of the ground disturbances, (2) the coupled vibrational modes of the composite pedestal-magnet system and, (3) the response of the system to ground disturbance.

Weng, W.T.; Chao, A.W.

1984-10-01

358

Damping phenomena in a wire rope vibration isolation system  

NASA Astrophysics Data System (ADS)

A study is presented of the dynamic characteristics of a wire rope vibration isolation system constructed with helical isolators, with emphasis placed on the analytical modeling of damping mechanisms in the system. An experimental investigation is described in which the static stiffness curve, hysteresis curves, phase plane trajectories, and frequency response curves are obtained. A semiempirical model having nonlinear stiffness, nth-power velocity damping, and variable Coulomb friction damping is developed, and the results are compared to experimental data. Several observations and conclusions are made about the dynamic phenomena in a typical wire rope vibration isolation system based on the experimental and semiempirical results.

Tinker, M. L.; Cutchins, M. A.

1992-08-01

359

Unstable vibration of roller mills  

NASA Astrophysics Data System (ADS)

The purpose of this study is to reveal the mechanism of unstable vibration occurring in the grinding operation of roller mills and to show the design guidelines for reducing the vibration. To study the basic cause of the unstable vibration, we first investigated the dynamic characteristics of the mill vibration in its stable state and its unstable state, using a small laboratory roller mill. This showed that the unstable vibration was due to the stick slip motion of the rollers. Further, the modal analysis showed that the natural frequency of the torsional driving system of the mill corresponded with the unstable vibration frequency. Next, we researched the frictional and compressive characteristics of the ground materials using a simplified test apparatus. This showed that the ground material has a negative-damping property known to be the cause of the self-excited vibration. Furthermore, we proposed the analytical vibration model for the simplified test apparatus considering the negative-damping property, as well as the corresponding equations of motion. By integrating them numerically, fluctuating phenomena similar to the experimental results were obtained.

Fujita, K.; Saito, T.

2006-10-01

360

The effect of whole body vibration on the H-reflex, the stretch reflex, and the short-latency response during hopping.  

PubMed

The effect of whole body vibration (WBV) on reflex responses is controversially discussed in the literature. In this study, three different modalities of reflex activation with increased motor complexity have been selected to clarify the effects of acute WBV on reflex activation: (1) the electrically evoked H-reflex, (2) the mechanically elicited stretch reflex, and (3) the short-latency response (SLR) during hopping. WBV-induced changes of the H-reflex, the stretch reflex, and the SLR during hopping were recorded in the soleus and gastrocnemius muscles and were analyzed before, during (only the H-reflex), immediately after, 5 min and 10 min after WBV. The main findings were that (1) the H-reflexes were significantly reduced during and at least up to 5 min after WBV, (2) the stretch reflex amplitudes were also significantly reduced immediately after WBV but recovered to their initial amplitudes within 5 min, and (3) the SLR during hopping showed no vibration-induced modulation. With regard to the modalities with low motor complexities, the decreased H- and stretch reflex responses are assumed to point toward a reduced Ia afferent transmission during and after WBV. However, it is assumed that during hopping, the suppression of reflex sensitivity is compensated by facilitatory mechanisms in this complex motor task. PMID:23802287

Ritzmann, R; Kramer, A; Gollhofer, A; Taube, W

2013-06-01

361

Time-domain parameter identification of aeroelastic loads by forced-vibration method for response of flexible structures subject to transient wind  

NASA Astrophysics Data System (ADS)

Slender structures representing civil, mechanical and aerospace systems such as long-span bridges, high-rise buildings, stay cables, power-line cables, high light mast poles, crane-booms and aircraft wings could experience vortex-induced and buffeting excitations below their design wind speeds and divergent self-excited oscillations (flutter) beyond a critical wind speed because these are flexible. Traditional linear aerodynamic theories that are routinely applied for their response prediction are not valid in the galloping, or near-flutter regime, where large-amplitude vibrations could occur and during non-stationary and transient wind excitations that occur, for example, during hurricanes, thunderstorms and gust fronts. The linear aerodynamic load formulation for lift, drag and moment are expressed in terms of aerodynamic functions in frequency domain that are valid for straight-line winds which are stationary or weakly-stationary. Application of the frequency domain formulation is restricted from use in the nonlinear and transient domain because these are valid for linear models and stationary wind. The time-domain aerodynamic force formulations are suitable for finite element modeling, feedback-dependent structural control mechanism, fatigue-life prediction, and above all modeling of transient structural behavior during non-stationary wind phenomena. This has motivated the developing of time-domain models of aerodynamic loads that are in parallel to the existing frequency-dependent models. Parameters defining these time-domain models can be now extracted from wind tunnel tests, for example, the Rational Function Coefficients defining the self-excited wind loads can be extracted using section model tests using the free vibration technique. However, the free vibration method has some limitations because it is difficult to apply at high wind speeds, in turbulent wind environment, or on unstable cross sections with negative aerodynamic damping. In the current research, new algorithms were developed based on forced vibration technique for direct extraction of the Rational Functions. The first of the two algorithms developed uses the two angular phase lag values between the measured vertical or torsional displacement and the measured aerodynamic lift and moment produced on the section model subject to forced vibration to identify the Rational Functions. This algorithm uses two separate one-degree-of-freedom tests (vertical or torsional) to identify all the four Rational Functions or corresponding Rational Function Coefficients for a two degrees-of-freedom (DOF) vertical-torsional vibration model. It was applied to a streamlined section model and the results compared well with those obtained from earlier free vibration experiment. The second algorithm that was developed is based on direct least squares method. It uses all the data points of displacements and aerodynamic lift and moment instead of phase lag values for more accurate estimates. This algorithm can be used for one-, two- and three-degree-of-freedom motions. A two-degree-of-freedom forced vibration system was developed and the algorithm was shown to work well for both streamlined and bluff section models. The uniqueness of the second algorithms lies in the fact that it requires testing the model at only two wind speeds for extraction of all four Rational Functions. The Rational Function Coefficients that were extracted for a streamlined section model using the two-DOF Least Squares algorithm were validated in a separate wind tunnel by testing a larger scaled model subject to straight-line, gusty and boundary-layer wind.

Cao, Bochao

362

Vibration generators  

SciTech Connect

Apparatus for generating vibrations in a medium, such as the ground, comprises a first member which contacts the medium, means , preferably electromagnetic, which includes two relatively movable members for generating vibrations in the apparatus and means operatively connecting the said two members to said first member such that the relatively amplitudes of the movements of said three members can be adjusted to match the impedances of the apparatus and the medium.

Lerwill, W.E.

1980-09-16

363

Localised Muscle Tissue Oxygenation During Dynamic Exercise With Whole Body Vibration  

PubMed Central

Abstract Despite increasing use of whole body vibration during exercise an understanding of the exact role of vibration and the supporting physiological mechanisms is still limited. An important aspect of exercise analysis is the utilisation of oxygen, however, there have been limited studies considering tissue oxygenation parameters, particularly during dynamic whole body vibration (WBV) exercise. The aim of this study was to determine the effect of adding WBV during heel raise exercises and assessing changes in tissue oxygenation parameters of the lateral gastrocnemius using Near Infra Red Spectroscopy (NIRS). Twenty healthy subjects completed ten alternating sets of 15 heel raises (vibration vs. no vibration). Synchronous oxygenation and motion data were captured prior to exercise to determine baseline levels, for the duration of the exercise and 20 sec post exercise for the recovery period. Both vibration and no vibration conditions elicited a characteristic increase in deoxyhaemoglobin and decreases in oxyhaemoglobin, total haemoglobin, tissue oxygenation index and normalised tissue haemoglobin index which are indicative of local tissue hypoxia. However, the addition of vibration elicited significantly lower (p < 0. 001) depletions in oxyhaemoglobin, total haemoglobin, normalised tissue haemoglobin index but no significant differences in deoxyhaemoglobin. These findings suggest that addition of vibration to exercise does not increase the cost of the exercise for the lateral gastrocnemius muscle, but does decrease the reduction in local muscle oxygenation parameters, potentially resulting from increased blood flow to the calf or a vasospastic response in the feet. However, further studies are needed to establish the mechanisms underlying these findings. Key points Whole body vibration affects tissue oxygenation of the lateral gastrocnemius. The underlying mechanism could be either increased blood flow or a vasospastic response in the feet. The local metabolic cost of heel raise activity on the lateral gastrocnemius does not appear to be increased by whole body vibration.

Robbins, Daniel; Elwell, Clare; Jimenez, Alfonso; Goss-Sampson, Mark

2012-01-01

364

Random vibrations of swings  

NASA Astrophysics Data System (ADS)

The paper considers a problem of random vibrations of swings—a pendulum with variable length. The goal of the paper is to estimate mean response energy of the system, subjected to external Gaussian white noise. The Energy Balance method is used to derive analytical results.

Iourtchenko, Daniil V.

2006-05-01

365

Vibration sensors  

NASA Astrophysics Data System (ADS)

Today, vibration sensors with low and medium sensitivities are in great demand. Their applications include robotics, navigation, machine vibration monitoring, isolation of precision equipment & activation of safety systems e.g. airbags in automobiles. Vibration sensors have been developed at SSPL, using silicon micromachining to sense vibrations in a system in the 30 - 200 Hz frequency band. The sensing element in the silicon vibration sensor is a seismic mass suspended by thin silicon hinges mounted on a metallized glass plate forming a parallel plate capacitor. The movement of the seismic mass along the vertical axis is monitored to sense vibrations. This is obtained by measuring the change in capacitance. The movable plate of the parallel plate capacitor is formed by a block connected to a surrounding frame by four cantilever beams located on sides or corners of the seismic mass. This element is fabricated by silicon micromachining. Several sensors in the chip sizes 1.6 cm x 1.6 cm, 1 cm x 1 cm and 0.7 cm x 0.7 cm have been fabricated. Work done on these sensors, techniques used in processing and silicon to glass bonding are presented in the paper. Performance evaluation of these sensors is also discussed.

Gupta, Amita; Singh, Ranvir; Ahmad, Amir; Kumar, Mahesh

2003-10-01

366

A brief history of free-response receiver operating characteristic paradigm data analysis.  

PubMed

In the receiver operating characteristic paradigm the observer assigns a single rating to each image and the location of the perceived abnormality, if any, is ignored. In the free-response receiver operating characteristic paradigm the observer is free to mark and rate as many suspicious regions as are considered clinically reportable. Credit for a correct localization is given only if a mark is sufficiently close to an actual lesion; otherwise, the observer's mark is scored as a location-level false positive. Until fairly recently there existed no accepted method for analyzing the resulting relatively unstructured data containing random numbers of mark-rating pairs per image. This report reviews the history of work in this field, which has now spanned more than five decades. It introduces terminology used to describe the paradigm, proposed measures of performance (figures of merit), ways of visualizing the data (operating characteristics), and software for analyzing free-response receiver operating characteristic studies. PMID:23583665

Chakraborty, Dev P

2013-04-12

367

The Shock and Vibration Bulletin.  

National Technical Information Service (NTIS)

Contents: Analysis of random responses for calculation of fatigue damage; Vibration trends analysis; Radiation resistance of cylindrical shells exhibiting axisymmetric mode shapes; Modal sensitivity study of a conical reentry vehicle to aerodynamically in...

1969-01-01

368

Sliding wear response of a leadedtin bronze: Influence of the counterface material characteristics  

NASA Astrophysics Data System (ADS)

Observations were made of the dry sliding wear behavior of a leaded-tin bronze against different counterface materials (stainless, EN8, and EN24 steels) over a range of applied pressures and speeds. The study showed that, in addition to sliding speed and pressure, the characteristics of the counterface materials greatly control the wear response of the bronze. The results were further substantiated by the characteristics of the wear surfaces, subsurface regions, and debris particles generated during the tests.

Pandey, J. P.; Prasad, B. K.

1998-02-01

369

Granular metamaterials for vibration mitigation  

NASA Astrophysics Data System (ADS)

Acoustic metamaterials that allow low-frequency band gaps are interesting for many practical engineering applications, where vibration control and sound insulation are necessary. In most prior studies, the mechanical response of these structures has been described using linear continuum approximations. In this work, we experimentally and theoretically address the formation of low-frequency band gaps in locally resonant granular crystals, where the dynamics of the system is governed by discrete equations. We investigate the quasi-linear behavior of such structures. The analysis shows that a stopband can be introduced at about one octave lower frequency than in materials without local resonances. Broadband and multi-frequency stopband characteristics can also be achieved by strategically tailoring the non-uniform local resonance parameters.

Gantzounis, G.; Serra-Garcia, M.; Homma, K.; Mendoza, J. M.; Daraio, C.

2013-09-01

370

Vibration Free Interferometer Mirror  

NASA Astrophysics Data System (ADS)

Optic tables may be an obstacle for the interferometric studies when they are exposed to mechanical vibrations in the particular frequency range. To reduce the mechanical noise, a moveable mirror of the FTIR spectrometer was used as an interferometer mirror. The vibration response of this mirror was investigated with a fiber optic Fabry-Perot interferometer that was built in our laboratory. The moveable mirror is mounted on a coil that is located between the permanent magnets. When the proper current is applied to the coil, the mirror becomes magnetically suspended and resistant to the mechanical vibrations. This work presents a non-contact vibration-monitoring technique with the extrinsic Fabry-Perot interferometric displacement sensor implemented using 4/125 ?m single-mode fiber with 3 dB fiber optic coupler. This device is based on a low finesse Fabry-Perot cavity which is formed by the end of a sensing optical fiber (fiber probe) and the magnetically-suspended mirror. The incoming light is emitted by a 660 nm laser diode. During the vibration test an ADC (NI 6070E) and a Labview software program were used. This technique helps to reduce the mechanical noise and to improve the stability of the interferometer.

Yaltkaya, S.

2007-04-01

371

Fuel assembly self-excited vibration and test methodology  

SciTech Connect

PWR fuel assemblies normally experience low amplitude, random vibration under normal reactor flow conditions. This normal fuel assembly vibration has almost no impact on grid-rod fretting wear. However, some fuel assembly designs experience a high resonant fuel assembly vibration under normal axial flow conditions. This anomalous fuel assembly vibration is defined as fuel assembly self-excitation vibration (FASE), because the assembly vibrates resonantly without any external periodic excitation force. Fuel assembly self-excitation vibration can cause severe grid-rod fretting if the assembly operates at the flow rate, which causes high fuel assembly vibration. This paper will describe the characteristics of fuel assembly self-excitation vibration and the test methodology to identify the fuel assembly vibration. Several fuel assembly designs are compared under standard test conditions. The causes for the fuel assembly self-excitation vibration are analyzed and discussed. The test acceptance criteria are defined for newly developed PWR fuel assemblies. (authors)

Lu, R.Y.; Broach, K. D.; McEvoy, J. J. [PWR Product Technologies, Westinghouse Electric Company, Drawer R, Columbia, SC, 29250 (United States)

2004-07-01

372

Characteristics of V/H response spectral ratio with recent Korean Peninsula events  

NASA Astrophysics Data System (ADS)

The vertical response spectra using the observed ground motion from the recent more than 30 macro earthquakes were analysed and then were compared to both the seismic design response spectra (Reg Guide 1.60), applied to the domestic nuclear power plants, and the Korean Standard Design Response Spectrum for general structures and buildings(1997). 176 vertical ground motions, without considering soil types, were used for normalization with respect to the peak acceleration value of each ground motion. The results showed that response spectrum has strong dependency on epicentral distance. The results also showed that the vertical response spectra revealed much higher values for frequency bands above 5-7 Hz than Reg. Guide(1.60). The results were also compared to the Korean Standard Response Spectrum for the 3 different soil types and showed that the vertical response spectra revealed much higher values for the frequency bands below 0.2 second (5Hz) than the Korean Standard Response Spectrum(SD soil condition). These spectral values dependent on frequency could be related to characteristics of the domestic crustal attenuation and the effect of each site amplification. However, through the qualitative improvements and quantitative enhancement of the observed ground motions, the conservation of vertical seismic design response spectrum should be considered more significantly for the frequency bands above 5 Hz. Vertical Response Spectrum Comparison of 0- 200km Response Spectrum with UBC Standard Response Spectrum.

Kim, J.

2010-12-01

373

Vibrations in Turbomachinery.  

National Technical Information Service (NTIS)

Contents: Vibration of systems with a single degree of freedom; Vibrations of systems with several degrees of freedom; Critical rotor speeds; Transverse vibrations of a rod; Transverse vibrations of elastic plates. (Author)

A. G. Kostyuk

1967-01-01

374

Vibrating Pipette Probe Mixer.  

National Technical Information Service (NTIS)

A vibrating pipette probe mixer is disclosed having means to vibrate the pipette so that when delivering extremely small quantities of liquid, accurate mixing and dispensing is achieved. The vibrating means may be either a mechanical vibrator attached to ...

1972-01-01

375

Police Response to Intimate Partner Violence in Canada: Do Victim Characteristics Matter?  

Microsoft Academic Search

This study examines the role of sociodemographic factors and violence characteristics in influencing women's reporting behaviors and types of police intervention received in response to intimate partner violence (IPV) in Canada. A subset of female respondents to Canada's 1999 General Social Survey who experienced physical or sexual IPV by a male perpetrator and who had contact with the police as

Betty Jo Barrett; Melissa St. Pierre; Nadine Vaillancourt

2011-01-01

376

Response Time of Broiler Chickens to Cimaterol: Meat Tenderness, Muscle Composition, Fiber Size, and Carcass Characteristics  

Microsoft Academic Search

The response time to cimaterol (CIM), a P-adrenergic agonist, by broiler chickens for carcass characteristics, muscle composition, muscle fiber size, catheptic enzyme activity, and tenderness was determined. Two trials were con- ducted in which chickens were fed a control diet (CON) containing 0 ppm of CIM or a diet contain- ing 1 ppm of CIM. Trial 1 consisted of 55,

B. L. Gwartney; S. J. Jones; C. R. Calkins

2010-01-01

377

Sliding wear response of a leadedtin bronze: Influence of the counterface material characteristics  

Microsoft Academic Search

Observations were made of the dry sliding wear behavior of a leaded-tin bronze against different counterface materials (stainless, EN8, and EN24 steels) over a range of applied pressures and speeds. The study showed that, in addition to sliding speed and pressure, the characteristics of the counterface materials greatly control the wear response of the bronze. The results were further substantiated

J. P. Pandey; B. K. Prasad

1998-01-01

378

The Association between SAT Prompt Characteristics, Response Features, and Essay Scores  

ERIC Educational Resources Information Center

This study investigated the relationship of prompt characteristics and response features with essay scores on the SAT Reasoning Test. A sample of essays was coded on a variety of features regarding their length and content. Analyses included descriptive statistics and computation of effect sizes, correlations between essay features and scores, and…

Kobrin, Jennifer L.; Deng, Hui; Shaw, Emily J.

2011-01-01

379

Response Characteristics of Temperature-S ensing Elements for Use in the Control of Jet Engines  

Microsoft Academic Search

The rate at which a temperature-se nsing element located in the gas stream of a jet engine responds to sudden changes in temperature is of great practical importance in the control and operation of such an engine. The factors that determine rate of response are discussed, and the significance of the characteristic time is emphasized. It is shown that laboratory

Andrew I. Dahl; Ernest F. Fiock

380

The genesis of torsional drillstring vibrations  

SciTech Connect

Inherent drilling characteristics of polycrystalline diamond compact (PDC) bits alone can be sufficient to excite severe torsional drillstring vibrations. The work presented in this paper augments previous findings that torsional vibrations can result from the drilling characteristics of the bit itself. Laboratory and field torsional measurements are compared with model results to show that the observed vibrations can be explained by a reduction in PDC bit torque as rotary speed increases. These torsional vibrations are important because they can cause drillpipe fatigue and may be severe enough to damage the bit. The model also is used to pinpoint possible solutions to the problem.

Brett, J. (Oil and Gas Consultants International Inc., Tulsa, OK (US))

1992-09-01

381

Dynamic response characteristics of local muscle blood flow regulatory mechanisms in human forearm exercise.  

PubMed

We sought to understand the nature of control mechanisms involved in the adaptation of exercising muscle hyperemia. Seven subjects performed rhythmic dynamic forearm exercise under two exercise conditions: small step 1 [step increase from rest to 40% peak forearm vascular conductance (FVC), in ml.min(-1).100 mmHg-1] for 5 min followed by small step 2 (further increase to 80% peak FVC for 5 min), and large step (step increase from rest to 80% peak FVC for 5 min). FVC data were fit with a two- (small step 1) and three-component (small step 2, large step) exponential as appropriate. For the rapid phase I response, FVC dynamic response characteristics (time delay, time constant) were not affected by the magnitude of the work intensity increase when the transition began from rest, but were slower in the 40-80% transition. Rest-80% gain was greater than either rest-40% or 40-80% transitions but represented the same proportion of the phase I + phase II gain across all transitions (57 vs. 56 vs. 57%, respectively, P = 0.975). For the slower phase II response, dynamic response characteristics were not affected by the magnitude of the work intensity increase when initiated from rest. The time constant was not altered when the transition began from exercise vs. rest. We conclude that 1) dynamic response characteristics of exercise hyperemia control mechanisms are not affected by the magnitude of work rate increase when forearm exercise is initiated from rest, 2) phase I but not phase II dynamic response characteristics are sensitive to baseline exercise intensity, and 3) the mechanisms contributing to phase I result in the same relative response magnitude, regardless of the size of the step increase in exercise intensity or the baseline from which it is initiated. PMID:15579568

Saunders, Natasha R; Pyke, Kyra E; Tschakovsky, Michael E

2004-12-03

382

Effect of handle size and hand handle contact force on the biodynamic response of the hand arm system under zh-axis vibration  

NASA Astrophysics Data System (ADS)

The influences of the handle size and of the hand forces exerted on a vibrating tool handle on the driving-point mechanical impedance (DPMI) response of the human hand arm system have been investigated through laboratory measurements performed on seven adult male subjects. Measurements were performed with three instrumented cylindrical handles with different diameters (30, 40 and 50 mm) exposed to two different levels of broadband random vibration (2.5 and 5.0 m/s2) along the zh axis, while the variations in the hand forces were realized through nine different combinations of grip (10, 30 and 50 N) and push (25, 50 and 75 N) forces. The static hand handle contact forces were also evaluated for each combination of grip and push forces, and each handle size through measurements of pressure distribution at the hand handle interface. The results have shown that the average contact force is a linear combination of the push and grip forces, while the contribution due to grip force is considerably larger than the push force and dependent upon the handle size. The hand handle coupling force, as defined in ISO/WD-15230, was further evaluated by summing the grip and push forces, which is independent of the handle size. The results have shown that the DPMI magnitude tends to increase with an increase in both the grip and push forces at frequencies above 25 Hz, while the increase in DPMI magnitude was better correlated with the coupling force below 200 Hz. A better correlation with the contact force, however, was attained at frequencies above 200 Hz, suggesting a stronger dependence on the grip force at higher frequencies. The DPMI magnitude response was also found to be influenced by the handle diameter. Increasing the handle size yielded higher peak DPMI magnitude response, specifically under medium to high hand handle coupling forces (30 N grip and 50 N push; 50 N grip and 75 N push).

Marcotte, P.; Aldien, Y.; Boileau, P.-É.; Rakheja, S.; Boutin, J.

2005-05-01

383

Finite Element Vibration Analysis of Cracked Plates in Tension.  

National Technical Information Service (NTIS)

A finite element method of analysis is developed to determine the vibration characteristics of an aircraft fuselage panel, containing a fatigue crack. Experimental observations show that as the length of the crack increases, the frequency of vibration rea...

M. Petyt

1968-01-01

384

Antibody Response to Bacterial Antigens: Characteristics of Antibody Response to Somatic Antigens of Salmonella typhimurium  

PubMed Central

The character of the antibody response in the rabbit to Salmonella typhimurium somatic (O) antigen was similar to the response to each of several serotypes of Shigella flexneri O antigens, namely a predominance of production of immunoglobulin M (IgM) antibody. Lipopolysaccharide protein (LPSP) and lipopolysaccharide (LPS) fractions of Salmonella O antigen differed significantly in both quantitative and qualitative aspects of their immunogenicity. LPSP elicited high levels of agglutinins and also induced the production of a significant amount of immunoglobulin G (IgG) antibody at a late period. LPS antigen elicited low levels of agglutinins which were exclusively IgM antibody. These results suggested that the chemical nature of the antigen is one important factor in the determination of the character of the antibody response. Further, it is suggested that the protein moiety of the O antigen complex is a carrier active in allowing induction of early IgM and of late IgG antibodies; in contrast, the lipid moiety may compete with this action of the carrier protein, thereby suppressing IgG antibody in the primary stage of the antibody-forming process.

Fukazawa, Y.; Shinoda, T.; Yomoda, T.; Tsuchiya, T.

1970-01-01

385

The global responses characteristics of a rotor/stator rubbing system with dry friction effects  

NASA Astrophysics Data System (ADS)

Rotor/stator rubbing systems may undertake a number of quite different responses. Recent experiments on rotor/stator rubbing have revealed that two or three different responses may coexist. In this paper the global response characteristics of a general rotor/stator rubbing system, which takes into account the dominant factors in the process of rotor/stator rubbing, especially, the dry friction effect that is mostly neglected in the previous works and is the main factor for the self-excited dry friction backward whirl, are studied. The different solutions of the piecewise nonlinear system are derived and their stability are analyzed to get the existence boundaries of the different responses. An overall picture of the global response characteristics of this model is then obtained by drawing the existence boundaries in a same parameter space. The present results provide good understanding on the coexistence of different rubbing responses observed in tests. Moreover, deeper insight into the types of coexistence of different rubbing responses and their relationship with the system parameters is gained.

Shang, Zhiyong; Jiang, Jun; Hong, Ling

2011-05-01

386

Vibration analysis to improve reliability and reduce failure; Proceedings of the Design Automation Conference, Cincinnati, OH, September 10-13, 1985  

SciTech Connect

Among the topics discussed are: turbomachinery tip rubs and interactive casting resonances; the transverse vibrational characteristics of an externally damaged pipe and performance of vibration monitoring for the prevention of gas turbine airfoil failures. Consideration is also given to: velocity response analysis of a spherical roller bearing; vibration monitoring of large pumps via a remote satellite stations; dynamic edge strain prediction in stiffened honeycomb panels; and fault-diagnosis for turbo-machines by means of vibration monitoring. Additional topics discussed include: early detection and diagnosis of faults rolling element bearings; spectral analysis of damped vibration by means of a modified version of the Prony method and guidelines for forced vibration in machine tools for use in protective maintenance and analysis.

Niskode, P.M.; Doepker, P.E.

1985-01-01

387

Dynamical simulations of photochemical reactions of trans-stilbene, and coherent control of C60 vibrational response  

NASA Astrophysics Data System (ADS)

Trans-to-cis photoisomerization of stilbene, induced by a femtosecond-scale laser pulse, has been observed in simulations employing semiclassical electron-radiation-ion dynamics (SERID). Our results demonstrate that trans-to-cis and cis-to-trans isomerization involve the same basic mechanism. We also predict that another photochemical reaction, photocyclization of trans-stilbene to 4a,4b-dihydrophenanthrene (DHP), can be achieved using an ultrashort laser pulse. Specifically, the trans-stilbene molecule is observed first to isomerize to cis-stilbene (as an excited-state intermediate) after more than one picosecond, and then to form a new bond to become DHP, after a few hundred additional femtoseconds. For C60 at low temperature, we predict that specific vibrational modes can be excited by optimally choosing the delay between two femtosecond-scale pulses.

Jiang, Chenwei; Li, Fuli; Xie, Ruihua; Allen, Roland

2009-10-01

388

Consideration of nonlinear vibration characteristic of object for irradiating highintensity ultrasonic waves by a point-convergence-type aerial ultrasonic source  

NASA Astrophysics Data System (ADS)

We considered a noncontact method that can detect internal defects in materials by analyzing frequency information obtained from the vibration of an object excited with highintensity ultrasonic waves. From our result, it is found that this method is able to detect internal defects in materials.

Osumi, Ayumu; Ito, Youichi

2012-09-01

389

Antigen-induced proliferation assay for rabbit T lymphocytes. I. Characteristics of the response.  

PubMed Central

An in vitro assay which measures specific antigen-induced proliferation of primed rabbit lymph node and peripheral blood cells is described. This response was found to be mediated by T cells, since it could be obtained with nylon-wool passed cells and cells which do not adhere to anti-Ig-coated plastic plates. The proliferative response was found to be highly antigen-specific and restricted to the draining lymph node if assessed up to 15 days post-priming. Purified T cells required antigen-pulsed accessory cells to proliferate. The proliferative response of peripheral blood lymphocytes was found to be low unless the lymphocytes were fractionated on insolubilized histamine. The histamine-adherent cells could suppress the above peripheral blood response, implying a certain regulatory role of suppressive cells in the periphery. The ease, reproducibility and specificity of the assay provides a simple method to evaluate the characteristics of a T-cell response in the rabbit.

de Baetselier, P; Vaeck, M; de Smet, W; Ron, Y

1980-01-01

390

On the separation of internal and boundary damage in slender bars using longitudinal vibration frequencies and equivalent linearization of damaged bolted joint response  

NASA Astrophysics Data System (ADS)

The problem of detecting localized large-scale internal damage in structures with imperfect bolted joints is considered. The proposed damage detection strategy utilizes the structural damping and an equivalent linearization of the bolted lap joint response to separate the combined boundary damage from localized large-scale internal damage. The frequencies are found approximately using asymptotic analysis and a perturbation technique. The proposed approach is illustrated on an example of longitudinal vibrations in a slender elastic bar with both ends clamped by bolted lap joints with different levels of damage. It is found that while the proposed method allows for the estimation of internal damage severity once the crack location is known, it gives multiple possible crack locations so that other methods (e.g., mode shapes) are required to obtain a unique crack location.

Argatov, Ivan; Butcher, Eric A.

2011-06-01

391

Health systems' responsiveness and its characteristics: a cross-country comparative analysis.  

PubMed

OBJECTIVES. Responsiveness has been identified as one of the intrinsic goals of health care systems. Little is known, however, about its determinants. Our objective is to investigate the potential country-level drivers of health system responsiveness. DATA SOURCE. Data on responsiveness are taken from the World Health Survey. Information on country-level characteristics is obtained from a variety of sources including the United Nations Development Program (UNDP). STUDY DESIGN. A two-step procedure. First, using survey data we derive a country-level measure of system responsiveness purged of differences in individual reporting behavior. Secondly, we run cross-sectional country-level regressions of responsiveness on potential drivers. PRINCIPAL FINDINGS. Health care expenditures per capita are positively associated with responsiveness, after controlling for the influence of potential confounding factors. Aspects of responsiveness are also associated with public sector spending (negatively) and educational development (positively). CONCLUSIONS. From a policy perspective, improvements in responsiveness may require higher spending levels. The expansion of nonpublic sector provision, perhaps in the form of increased patient choice, may also serve to improve responsiveness. However, these inferences are tentative and require further study. PMID:21762144

Robone, Silvana; Rice, Nigel; Smith, Peter C

2011-07-15

392

Experimental and mathematical investigation of response characteristics and aging phenomena in safety fuse elements  

NASA Astrophysics Data System (ADS)

Fuse elements were tested in air and sand for currents between 80 and 210 A, and were investigated using the finite element programming system ADIMAT. The long term melting behavior of fuses with soldered coating is discussed. The dissociation phenomena in fuse-solder pairs are explained. The aging behavior in case of cyclic overcurrent loading was determined. The response characteristics of fuse-solder pairs were obtained using the finite element method. The test results provide the heat conduction and heat capacity characteristics of safety sand as a function of temperature.

Hofmann, Matthias

393

Experimental validation of a numerical model for subway induced vibrations  

NASA Astrophysics Data System (ADS)

This paper presents the experimental validation of a coupled periodic finite element-boundary element model for the prediction of subway induced vibrations. The model fully accounts for the dynamic interaction between the train, the track, the tunnel and the soil. The periodicity or invariance of the tunnel and the soil in the longitudinal direction is exploited using the Floquet transformation, which allows for an efficient formulation in the frequency-wavenumber domain. A general analytical formulation is used to compute the response of three-dimensional invariant or periodic media that are excited by moving loads. The numerical model is validated by means of several experiments that have been performed at a site in Regent's Park on the Bakerloo line of London Underground. Vibration measurements have been performed on the axle boxes of the train, on the rail, the tunnel invert and the tunnel wall, and in the free field, both at the surface and at a depth of 15 m. Prior to these vibration measurements, the dynamic soil characteristics and the track characteristics have been determined. The Bakerloo line tunnel of London Underground has been modelled using the coupled periodic finite element-boundary element approach and free field vibrations due to the passage of a train at different speeds have been predicted and compared to the measurements. The correspondence between the predicted and measured response in the tunnel is reasonably good, although some differences are observed in the free field. The discrepancies are explained on the basis of various uncertainties involved in the problem. The variation in the response with train speed is similar for the measurements as well as the predictions. This study demonstrates the applicability of the coupled periodic finite element-boundary element model to make realistic predictions of the vibrations from underground railways.

Gupta, S.; Degrande, G.; Lombaert, G.

2009-04-01

394

The sense of flutter-vibration evoked by stimulation of the hairy skin of primates: Comparison of human sensory capacity with the responses of mechanoreceptive afferents innervating the hairy skin of monkeys  

Microsoft Academic Search

We have studied the response properties of peripheral myelinated fibers ending in the hairy skin of the Rhesus monkey, activated by sinusoidal mechanical stimulation. In parallel experiments we measured thresholds of the sensations evoked in man by identical stimuli, delivered under similar conditions to corresponding areas of the hairy skin. We found that the sense of low frequency vibration (i.

Michael M. Merzenich; Thomas Harrington

1969-01-01

395

Analytic and Experimental Investigation of Rotordynamic Response and Backward Whirl Induced by Split Resonance.  

National Technical Information Service (NTIS)

Rotordynamic response phenomena, including backward whirl, were investigated both analytically and experimentally. A two degrees-of-freedom rotor model was developed to simulate the steady state, lateral vibration characteristics of a simply supported, si...

C. E. Vejvoda

1994-01-01

396

Food vibrations: Asian spice sets lips trembling.  

PubMed

Szechuan pepper, a widely used ingredient in the cuisine of many Asian countries, is known for the tingling sensation it induces on the tongue and lips. While the molecular mechanism by which Szechuan pepper activates tactile afferent fibres has been clarified, the tingling sensation itself has been less studied, and it remains unclear which fibres are responsible. We investigated the somatosensory perception of tingling in humans to identify the characteristic temporal frequency and compare this to the established selectivity of tactile afferents. Szechuan pepper was applied to the lower lip of participants. Participants judged the frequency of the tingling sensation on the lips by comparing this with the frequencies of mechanical vibrations applied to their right index finger. The perceived frequency of the tingling was consistently at around 50 Hz, corresponding to the range of tactile RA1 afferent fibres. Furthermore, adaptation of the RA1 channel by prolonged mechanical vibration reliably reduced the tingling frequency induced by Szechuan pepper, confirming that the frequency-specific tactile channel is shared between Szechuan pepper and mechanical vibration. Combining information about molecular reactions at peripheral receptors with quantitative psychophysical measurement may provide a unique method for characterizing unusual experiences by decomposing them into identifiable minimal units of sensation. PMID:24026819

Hagura, Nobuhiro; Barber, Harry; Haggard, Patrick

2013-09-11

397

Sliding wear response of a leadedtin bronze: Influence of the counterface material characteristics  

Microsoft Academic Search

Observations were made of the dry sliding wear behavior of a leaded-tin bronze against different counterface materials (stainless,\\u000a EN8, and EN24 steels) over a range of applied pressures and speeds. The study showed that, in addition to sliding speed and\\u000a pressure, the characteristics of the counterface materials greatly control the wear response of the bronze. The results were\\u000a further substantiated

J. P. Pandey; B. K. Prasad

1998-01-01

398

Sliding Wear Response of a Leaded-Tin Bronze: Influence of the Counterface Material Characteristics  

Microsoft Academic Search

Observations were made of the dry sliding wear behavior of a leaded-tin bronze against different counterface materials (stainless,\\u000a EN8, and EN24 steels) over a range of applied pressures and speeds. The\\u000a study showed that, in addition to sliding speed and pressure, the characteristics of the counterface materials\\u000a greatly control the wear response of the bronze. The results were further substantiated

J. P. Pandey; B. K. Prasad

1998-01-01

399

Osmotic response in Lactobacillus casei ATCC 393: biochemical and biophysical characteristics of membrane  

Microsoft Academic Search

The biochemical and biophysical properties of the membrane and some general characteristics of the response of Lactobacillus casei ATCC 393 (reclassified Lactobacillus zeae) to hyperosmotic conditions were studied. Under hypertonic conditions, the hydrophobicity and the bile salt sensitivity of the cultures were increased. The glycolipid AcylH3DG is only present in membranes of NaCl containing medium, whereas, H4DG undergoes a significant

M. Cecilia Machado; Claudia S López; Horacio Heras; Emilio A Rivas

2004-01-01

400

Behavioral Responses of Daphnia Magna to Stresses of Chemicals with Different Toxic Characteristics  

Microsoft Academic Search

Behavior of an organism is affected by exposure to toxic chemicals. However, less has been known about behavioral responses\\u000a of an organism to stresses of toxic chemicals with different toxic characteristics. In present work, Daphnia magna Straus was exposed to gradient concentrations of deltamethrin, chlorothalonil and nitrofen and the behavioral changes of\\u000a Daphnia magna under different stress were examined. The

Zongming Ren; Zhiliang Li; Mei Ma; Zijian Wang; Rongshu Fu

2009-01-01

401

Characteristics of identifying linear dynamic models from impulse response data using Prony analysis  

SciTech Connect

The purpose of the study was to investigate the characteristics of fitting linear dynamic models to the impulse response of oscillatory dynamic systems using Prony analysis. Many dynamic systems exhibit oscillatory responses with multiple modes of oscillations. Although the underlying dynamics of such systems are often nonlinear, it is frequently possible and very useful to represent the system operating about some set point with a linear model. Derivation of such linear models can be done using two basic approaches: model the system using theoretical derivations and some linearization method such as a Taylor series expansion; or use a curve-fitting technique to optimally fit a linear model to specified system response data. Prony analysis belongs to the second class of system modeling because it is a method of fitting a linear model to the impulse response of a dynamic system. Its parallel formulation inherently makes it well suited for fitting models to oscillatory system data. Such oscillatory dynamic effects occur in large synchronous-generator-based power systems in the form of electromechanical oscillations. To study and characterize these oscillatory dynamics, BPA has developed computer codes to analyze system data using Prony analysis. The objective of this study was to develop a highly detailed understanding of the properties of using Prony analysis to fit models to systems with characteristics often encountered in power systems. This understanding was then extended to develop general rules-of-thumb'' for using Prony analysis. The general characteristics were investigated by performing fits to data from known linear models under controlled conditions. The conditions studied include various mathematical solution techniques; different parent system configurations; and a large variety of underlying noise characteristics.

Trudnowski, D.J.

1992-12-01

402

Characteristics of identifying linear dynamic models from impulse response data using Prony analysis  

SciTech Connect

The purpose of the study was to investigate the characteristics of fitting linear dynamic models to the impulse response of oscillatory dynamic systems using Prony analysis. Many dynamic systems exhibit oscillatory responses with multiple modes of oscillations. Although the underlying dynamics of such systems are often nonlinear, it is frequently possible and very useful to represent the system operating about some set point with a linear model. Derivation of such linear models can be done using two basic approaches: model the system using theoretical derivations and some linearization method such as a Taylor series expansion; or use a curve-fitting technique to optimally fit a linear model to specified system response data. Prony analysis belongs to the second class of system modeling because it is a method of fitting a linear model to the impulse response of a dynamic system. Its parallel formulation inherently makes it well suited for fitting models to oscillatory system data. Such oscillatory dynamic effects occur in large synchronous-generator-based power systems in the form of electromechanical oscillations. To study and characterize these oscillatory dynamics, BPA has developed computer codes to analyze system data using Prony analysis. The objective of this study was to develop a highly detailed understanding of the properties of using Prony analysis to fit models to systems with characteristics often encountered in power systems. This understanding was then extended to develop general ``rules-of-thumb`` for using Prony analysis. The general characteristics were investigated by performing fits to data from known linear models under controlled conditions. The conditions studied include various mathematical solution techniques; different parent system configurations; and a large variety of underlying noise characteristics.

Trudnowski, D.J.

1992-12-01

403

Butterfly visual characteristics and ontogeny of responses to butterflies by a specialized tropical bird  

Microsoft Academic Search

The responses of two adult and three hand-reared, naive young rufous-tailed jacamars (Galbula ruficauda) to local butterflies were studied in feeding experiments. Four behavioural characteristics distinguish jacamars from other less specialized avian predators: (1) Exposed to butterflies for the first time, naive young jacamars would attack butterflies without showing signs of inhibition. Unacceptable butterflies, once captured, were taste-rejected quickly, and

PENG CHAI

1996-01-01

404

Characteristics of identifying linear dynamic models from impulse response data using Prony analysis  

NASA Astrophysics Data System (ADS)

The purpose of the study was to investigate the characteristics of fitting linear dynamic models to the impulse response of oscillatory dynamic systems using Prony analysis. Many dynamic systems exhibit oscillatory responses with multiple modes of oscillations. Although the underlying dynamics of such systems are often nonlinear, it is frequently possible and very useful to represent the system operating about some set point with a linear model. Derivation of such linear models can be done using two basic approaches: model the system using theoretical derivations and some linearization method such as a Taylor series expansion; or use a curve-fitting technique to optimally fit a linear model to specified system response data. Prony analysis belongs to the second class of system modeling because it is a method of fitting a linear model to the impulse response of a dynamic system. Its parallel formulation inherently makes it well suited for fitting models to oscillatory system data. Such oscillatory dynamic effects occur in large synchronous-generator-based power systems in the form of electromechanical oscillations. To study and characterize these oscillatory dynamics, BPA has developed computer codes to analyze system data using Prony analysis. The objective of this study was to develop a highly detailed understanding of the properties of using Prony analysis to fit models to systems with characteristics often encountered in power systems. This understanding was then extended to develop general 'rules-of-thumb' for using Prony analysis. The general characteristics were investigated by performing fits to data from known linear models under controlled conditions. The conditions studied include various mathematical solution techniques, different parent system configurations, and a large variety of underlying noise characteristics.

Trudnowski, D. J.

1992-12-01

405

Analysis of the Dynamic Response of a Rolling String-Type Tire Model to Lateral Wheel-Plane Vibrations  

Microsoft Academic Search

A theory has been developed for the analysis and prediction of the dynamic frequency response of lateral force and moment acting upon a pneumatic tire when the wheel is moved laterally and swivelled about the vertical axis. The theory establishes the force and moment response of a tire model which consists of a stretched circular string with mass, elastically supported

HANS B. PACEJKA

1972-01-01

406

A Vibration Analysis Of Vehicle Frame  

NASA Astrophysics Data System (ADS)

Importance in the development of offroad racing vehicle for the SAEINDIA's BAJA competition has raised the value of dynamic analysis under severe uneven loading. The dynamic analysis is carried out by the finite element method simulation thereby predicting failure modes of the vehicle frame under vibration analysis. This work investigates the vibration characteristics of the frame including the natural frequencies and mode shapes

Rajput, Yogendra S.; Sharma, Vikas; Sharma, Shivam; Saxena, Gaurav

2013-03-01

407

ESPY measurements of submerged composite plate vibrations  

Microsoft Academic Search

An Electronic Speckle pattern interferometer (ESPI) was constructed which performs full-field surface displacement measurements. This measurement technique when combined with a single-point measurement known as laser vibrometry, can completely determine the vibrational characteristics of complex structures. This information can, in turn, be used for nondestructive testing as well as for modal analysis. One NDT E technique is to vibrationally excite

Pechersky

1990-01-01

408

New PDC bit design reduces vibrational problems  

Microsoft Academic Search

A new polycrystalline diamond compact (PDC) bit design combines cutter layout, load balancing, unsymmetrical blades and gauge pads, and spiraled blades to reduce problematic vibrations without limiting drilling efficiency. Stabilization improves drilling efficiency and also improves dull characteristics for PDC bits. Some PDC bit designs mitigate one vibrational mode (such as bit whirl) through drilling parameter manipulation yet cause or

G. Mensa-Wilmot; W. L. Alexander

1995-01-01

409

Vibrotactile thresholds at the sole of the foot: effect of vibration frequency and contact location.  

PubMed

Studies of vibration perception in the glabrous skin of the human hand have identified four mechanoreceptor channels, with each channel showing characteristic variations in thresholds with variations in the frequency of vibration and the area of vibration excitation. To advance understanding of the channels mediating vibration perception on the sole of the foot, this study determined how thresholds depend on the frequency of vibration, the location on the foot (the big toe, the ball of the foot, and the heel), and the gap between a vibrating probe and a fixed surround. Thresholds at the three locations were obtained at the 12 preferred one-third octave centre frequencies from 20 to 250 Hz using a 6-mm diameter probe with both a 10-mm and a 20-mm diameter surround. With the 10-mm surround, the displacement thresholds at all three locations showed flat responses from 20 to 40 Hz. With both the 10-mm and the 20-mm surround, the displacement thresholds at the three locations showed "U-shaped" responses from 40 to 250 Hz. Relative to thresholds obtained with the 20-mm surround, thresholds obtained with the 10-mm surround were lower at the toe and the heel with 20- and 25-Hz vibration, but higher at the ball of the foot with 31.5- to 250-Hz vibration. It is concluded that absolute thresholds for the perception of vibration at the sole of the foot show important variations with location and with contact conditions and tend to be mediated by the NP I channel in the range from about 20 to 40 Hz and the P channel from about 40 to 250 Hz. PMID:22115026

Gu, Cheng; Griffin, Michael J

2011-11-25

410

Dynamic response of active twist rotor blades  

Microsoft Academic Search

Dynamic characteristics of active twist rotor (ATR) blades are investigated analytically and experimentally in this paper. The ATR system is intended for vibration and potentially for noise reductions in helicopters through individual blade control. An aeroelastic model is developed to identify frequency response characteristics of the ATR blade with integral, generally anisotropic, strain actuators embedded in its composite construction. An

Carlos E. S. Cesnik; Sang Joon Shin; Matthew L. Wilbur

2001-01-01

411

Vibration in cutting processes  

Microsoft Academic Search

Any cutting process is accompanied by vibration. With moderate amplitudes, the vibration may be ignored; with considerable amplitudes, stability loss is possible [1]. Much research has focused on eliminating the negative consequences of vibration in cutting processes. Some papers focus on the positive influence of vibration on machining [2]: they basically deal with vibrocutting and cutting accompanied by vibration of

M. P. Kozochkin

2009-01-01

412

Study on Development of the Seated Human Body System Exposed to Vehicular Ride Vibration Environment  

Microsoft Academic Search

\\u000a This paper tries to find an appropriate structure of human model, which can better represent the characteristics of the real\\u000a human body, using the apparent mass (APMS) and head transmissibility (STHT) in vertical vibrations. The model parameters were\\u000a identified through minimizing an error function comprising the measured and model response in terms of magnitude and phase\\u000a characteristics of APMS and

S. Rodean; M. Arghir

413

Identification of root cause and abatement of vibration of monochromator.  

SciTech Connect

Silicon crystal mirrors are used to reflect high-intensity X-ray beams. A large amount of heat is generated in each mirror. To minimize the effect of thermal expansion on the crystal mirrors, heat is removed by pumping liquid gallium (with a boiling point of 29.8 C) through passages in the crystal mirrors. During system operation, mirror motion should be kept to an acceptable level to avoid performance degradation. There are many potential sources of excitation to the crystal assembly; one such source is the flowing gallium. Two series of tests were performed earlier for a near-prototypical gallium cooling system (1-2). This paper describes a series of tests to measure the general vibration response characteristics of critical components in the monochromator system that contains the mirrors. The main objective of this work is to identify the root cause of vibration and to recommend general guidelines for abatement of vibration. This is achieved by performing many tests to understand the response characteristics under various conditions, by analysis of the response data, and by use of some theoretical considerations.

Jendrzejczyk, J. A.

1998-01-13

414

Surface characteristics and osteoblastic cell response to titanium-8tantalum-3neobium alloy  

NASA Astrophysics Data System (ADS)

In the present study, the surface properties and osteblastic responses to a titanium-8%tantalum-3%niobium (Ti-8Ta-3Nb) alloy were investigated in vitro. The surface roughness and morphology of all samples appeared similar. The surface of the Ti-8Ta-3Nb alloy was more hydrophilic than those of commercially pure titanium (TiS) and Ti-6Al-4V alloy. The Ti-8Ta-3Nb alloy had a better cellular response with regard to proliferation and ALP activity. The present study showed improved surface characteristics and osteoblastic response to the Ti-8Ta-3Nb alloy compared to TiS and Ti-6Al-4V alloy.

Cui, De-zhe; Park, Ki-Deog; Lee, Kyung-Ku; Jung, Young-Suk; Lee, Bo-Ah; Lee, Yang-Jin; Kim, Ok-Su; Chung, Hyun-Ju; Kim, Young-Joon

2012-12-01

415

Vibrations of Euler's disk.  

PubMed

A model of a partially deformable Euler disk is presented that allows transverse vibrations to be treated with the techniques of classical analytical mechanics. The model clearly shows that the increasing audible frequency produced during motion can be directly related to the forcing effect of the reaction and the angular velocity of the contact point. The material of the disk seems to play a role in affecting the intensity and quality of the sound, but not its pitch. Moreover, the friction force grows rapidly with the decline of the disk, thus causing the slipping that is partially responsible for the abrupt end of the motion. The model also supports the conjecture [P. Kessler and O. M. O'Reilly, Regul. Chaotic Dyn. 7, 49 (2002)] that the vibrations themselves contribute to this phenomenon by causing a loss of contact with the surface at small angles of inclination. PMID:16089897

Villanueva, Roberto; Epstein, Marcelo

2005-06-21

416

Design Method for Dynamic Vibration Absorbers Considering Excitation Frequency Range  

Microsoft Academic Search

A new optimum design method for dynamic vibration absorbers is proposed for cases when the dynamic characteristics of the primary system vary by a considerable amount and the excitation frequency fluctuates in a small range. When the excitation frequency is constant, it is well known that an undamped dynamic vibration absorber is very effective for attenuating the vibration amplitude of

Yoshio Inoue; Kyoko Shibata

2010-01-01

417

Numerical Modelling of Rubber Vibration Isolators: identification of material parameters  

Microsoft Academic Search

Rubber vibration isolators are used for vibration isolation of engines at high frequencies. To make a good prediction regarding the characteristics of a vibration isolator in the design process, numerical models can be used. However, for a reliable prediction of the dynamic behavior of the isolator, the rubber material parameters have to be known. In practice the material parameters have

Clemens Beijers; Bram Noordman; Boer de André

2004-01-01

418

New PDC bit design reduces vibrational problems  

SciTech Connect

A new polycrystalline diamond compact (PDC) bit design combines cutter layout, load balancing, unsymmetrical blades and gauge pads, and spiraled blades to reduce problematic vibrations without limiting drilling efficiency. Stabilization improves drilling efficiency and also improves dull characteristics for PDC bits. Some PDC bit designs mitigate one vibrational mode (such as bit whirl) through drilling parameter manipulation yet cause or excite another vibrational mode (such as slip-stick). An alternative vibration-reducing concept which places no limitations on the operational environment of a PDC bit has been developed to ensure optimization of the bit`s available mechanical energy. The paper discusses bit stabilization, vibration reduction, vibration prevention, cutter arrangement, load balancing, blade layout, spiraled blades, and bit design.

Mensa-Wilmot, G.; Alexander, W.L. [Smith International Inc., Houston, TX (United States)

1995-05-22

419

Seminar on Ship Vibration.  

National Technical Information Service (NTIS)

Contents: Pressure fluctuations induced by a cavitating propeller; Experiences in defining propeller induced hull forces; Ship vibration calculations; Current trends in vibration calculation methods; Ship vibration measurements; State of the art of ship's...

1982-01-01

420

"20 Tons Moved Mass" - The Ariane 5 ESC-A Lower Assembly Vibration Test  

NASA Astrophysics Data System (ADS)

The new cryogenic upper stage of the Ariane 5 launcher (ESC-A) underwent a mechanical test campaign at IABG's Space Test Centre in 2003 under the responsibility of EADS Space Transportation. The campaign focussed on ESC-A's Lower Assembly and was highlighted by a vibration test of a configuration consisting of the filled LOX Tank, the Inter Tank Structure, the Equipped Thrust Frame and the Engine. The requirements for this vibration test exceeded the nominal system limitations of the test facility in several respects. The test configuration required a stiff vibration input interface at a height of 3 m above the shaker table, realized by a heavy conical test adapter. The resulting test set-up had dimensions of 5.4 m in diameter and 4.5 m in height and an overall test set-up mass of 25 t, including the required vibration tables and test adapters. For the measurement of all responses of interest, more than 520 measurement channels had to be provided. This presentation explains how the challenges of the ESC-A Lower Assembly Vibration Test were mastered. It describes the facility set-up, the mechanical and measurement set-up as well as some characteristic features of the test performance of this extraordinary vibration test.

Baumgartl, R.

2004-08-01

421

Turbine blade vibration dampening  

DOEpatents

The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass "M" or combined mass "CM" of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics.

Cornelius, Charles C. (San Diego, CA); Pytanowski, Gregory P. (San Diego, CA); Vendituoli, Jonathan S. (San Diego, CA)

1997-07-08

422

Turbine blade vibration dampening  

DOEpatents

The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass ``M`` or combined mass ``CM`` of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics. 5 figs.

Cornelius, C.C.; Pytanowski, G.P.; Vendituoli, J.S.

1997-07-08

423

Contactless photoelectric fiberglass vibration transducers  

Microsoft Academic Search

There exist eddy-current, electret, capacitive, and optical methods for measuring vibration parameters of the electronic industry's products. The precision characteristics of electret, eddy-current, and capacitive transducers depend to a considerable extent on the utilization conditions and the materials of the electronic industry's elements, as well as the presence of external electric or magnetic fields, and they are considerably less stable

E. A. Zak; G. A. Zalodeev; V. D. Malinskii

1976-01-01

424

Helicopter Transmission Vibration and Noise Reduction Program.  

National Technical Information Service (NTIS)

A combined analytical and test program has been performed to develop a method for analytically determining the vibration and noise characteristics of a helicopter transmission. This effort included formulation of the necessary analytical method, validatio...

M. A. Bowes N. Giansante R. B. Bossler A. Berman

1977-01-01

425

Propagation characteristic of atmospheric responses to abnormal warm SST in the Kuroshio Extension in winter  

NASA Astrophysics Data System (ADS)

The propagation characteristic of atmospheric responses to the abnormal warm sea-surface temperature (SST) in the Kuroshio Extension in winter was investigated using National Centre for Atmospheric Research CAM3.0. The results show that geopotential height perturbations at 500 hPa occupy much of the mid- and high-latitude areas north of 20°N and are stronger in winter and spring than in summer. Power spectrum analysis reveals that the perturbations contain both quasi-biweekly and intraseasonal oscillations. In the latitude band with maximum perturbation amplitude, the oscillations propagate mainly eastward. The centers of dominant oscillations are situated in the mid- and higher-latitude areas north to 40°N. The perturbations in the Arctic mainly propagate meridionally, whereas those south of the Arctic propagate zonally, at a steady-phase velocity basically. The propagation characteristics of wind perturbations and temperature perturbations are similar to those of geopotential height perturbations.

Xiaodan, Wang; Zhong, Zhong; Jianwen, Liu; Linlin, Qi

2012-04-01

426

Fiber optic sensor for detection of ground vibrations  

NASA Astrophysics Data System (ADS)

The paper describes a new fiber optic sensor based on the Mach-Zehnder and Sagnac hybrid interferometer to measure the ground vibrations is investigated. The frequency characteristic of vibration signal is analyzed via fast Fourier transform (FFT) and Gabor transform. It provides highly sensitive for low frequency measurement. The fiber optic vibration sensing system presented in this research is appropriate to utilize for sensing ground vibration between 10 ~ 200Hz frequency range.

Liang, Tsair-Chun; Lin, Yung-Li

2012-01-01

427

Full-scale dynamic response of an RC building under weak seismic motions using earthquake recordings, ambient vibrations and modelling  

Microsoft Academic Search

In countries with a moderate seismic hazard, the classical methods developed\\u000afor strong motion prone countries to estimate the seismic behaviour and\\u000asubsequent vulnerability of existing buildings are often inadequate and not\\u000afinancially realistic. The main goals of this paper are to show how the modal\\u000aanalysis can contribute to the understanding of the seismic building response\\u000aand the good

Clotaire Michel; Philippe GUEGUEN; Saber El Arem; Jacky Mazars; Panagiotis Kotronis

2009-01-01

428

Analysis of the Dynamic Response of a Shield Tunnel in Soft Soil Under a Metro-Train Vibrating Load  

Microsoft Academic Search

This paper concerns the impact of an operating metro train on the structure of a shield tunnel lining and its soft foundation. An elastoplastic 3D dynamic finite difference model was established by using the FLAC3D numerical software. By fully considering the joints, the A-B-K segments and the soft stratum, the dynamic response of the shield tunnel buried in thick, soft

Fei-huang DENG; Hai-hong MO; Qing-jun ZENG; Xiao-jie YANG

2006-01-01

429

SEMI-ANALYTICAL APPROACH TO THE NON-LINEAR DYNAMIC RESPONSE PROBLEM OF S–S AND C–C BEAMS AT LARGE VIBRATION AMPLITUDES PART I: GENERAL THEORY AND APPLICATION TO THE SINGLE MODE APPROACH TO FREE AND FORCED VIBRATION ANALYSIS  

Microsoft Academic Search

In a previous series of papers [1–3], a general model based on Hamilton's principle and spectral analysis was developed for non-linear free vibrations occurring at large displacement amplitudes of fully clamped beams and rectangular homogeneous and composite plates. As an introduction to the present work, concerned with the forced non-linear response of C–C and S–S beams, the above model has

L. Azrar; R. Benamar; R. G. White

1999-01-01

430

Vibration syndrome and vibration in pedestal grinding.  

PubMed Central

At one Finnish foundry all the workers had typical symptoms of vibration induced white finger (VWF) after they began using a new type of pedestal grinding machine. The objectives of this study were to establish the severity of the symptoms and the difference in vibration exposure between the new and the old machines. Vibration detection thresholds and grip forces were measured, as well as the vibration in the casting and in the wrist simultaneously. The mean latency for VWF among the grinders was 10.3 months after the change of pedestal grinding machines. All the grinders had numbness in their hands. The vibration detection threshold was significantly higher for the grinders than for their referents. At the same circle speed, the new wheels caused vibration levels up to 12 dB more than the old wheels. The circle speed had a slight influence on the vibration. The vibration levels of light (0.5 kg) casting were up to 25 dB higher than the heavy (5 kg) casting. The use of a pneumatic pressing device decreased the vibration levels in the wrist by 5-10 dB. The increase in vibration, which occurred when the new wheels were taken into use, was too small to explain such a dramatic outbreak of VWF. This led to the conclusion that some other feature such as the impulse character of the vibration also contributed to the effects of vibration.

Starck, J; Farkkila, M; Aatola, S; Pyykko, I; Korhonen, O

1983-01-01

431

Vibration measurements in the classical guitar  

Microsoft Academic Search

Some measurements are described that pertain to the high frequency behaviour of the vibrations of the string and soundboard of the guitar.Three isolated soundboards of different woods were compared with respect to their early decay times (by means of measurements of their vibrational impulse responses), in order to assess its possible use as an objective measure of the reverberation time

Ricardo R. Boullosa

2002-01-01

432

Wave Intensity Analysis of High Frequency Vibrations  

Microsoft Academic Search

In the statistical energy analysis (SEA) approach to high frequency dynamics it is assumed that the vibrational wavefield in each component of an engineering structure is diffuse. In some instances the directional filtering effects of structural joints can lead to highly non-diffuse wavefields, and in such cases SEA will yield a very poor estimate of the vibrational response. An alternative

Robin S. Langley; Ahmet N. Bercin

1994-01-01

433

Nonlinear response and failure characteristics of internally pressurized composite cylindrical panels  

SciTech Connect

Results of an experimental and analytical study of the nonlinear response and failure characteristics of internally pressurized 4- to 16-ply-thick graphite-epoxy cylindrical panels are presented. Specimens with clamped boundaries simulating the skin between two frames and two stringers of a typical transport fuselage were tested to failure. Failure results of aluminum specimens are compared with the graphite-epoxy test results. The specimens failed at their edges where the local bending gradients and interlaminar stresses are maximum. STAGS nonlinear two-dimensional shell analysis computer code results are used to identify regions of the panels where the response is independent of the axial coordinate. A geometrically nonlinear one-dimensional cylindrical panel analysis was derived and used to determine panel response and interlaminar stresses. Inclusion of the geometric nonlinearity was essential for accurate prediction of panel response. Measurements of panel radius and edge circumferential displacements associated with specimen slipping were also required in the one-dimensional analysis for good correlation between analytical and experimental results. Some panels failed with significant damage in the form of tensile fiber breaks and ply delaminations preceding the ultimate pressure. Other panels failed suddenly without any apparent damage preceding the ultimate pressure.

Boitnott, R.L.

1985-01-01

434

Characteristics of resistivity log response of oil layers under polymer flooding  

NASA Astrophysics Data System (ADS)

Resistivity log responses are different when the oil layers is filled by a polymer solution or water and it seriously affects the log interpretation of the water flooded layer. In this paper, we first analyze the electrical properties of the polymer solution. Then, according to the different processes for polymer flooding the reservoir, we perform rock resistivity experiments and analyze the rock resistivity variations in different displacement phases. We also compare the resistivity log responses of oil layers filled with the polymer solution to those filled with water. The results show that when displacing the oil-bearing core by different polymers, the resistivity changes monotonously decrease and show either "W" type or "S" type. The resistivity log responses are weak when displacing water and there is no flooded show if the oil layer is injected by a fresh water polymer solution. If the oil layer is injected by a sewage polymer solution, the resistivity log response has similar characteristic as a polluted water flooded layer.

Yu, Jun; Pan, Bao-Zhi; Yang, Qing-Shan

2012-06-01

435

ROCView: prototype software for data collection in jackknife alternative free-response receiver operating characteristic analysis  

PubMed Central

ROCView has been developed as an image display and response capture (IDRC) solution to image display and consistent recording of reader responses in relation to the free-response receiver operating characteristic paradigm. A web-based solution to IDRC for observer response studies allows observations to be completed from any location, assuming that display performance and viewing conditions are consistent with the study being completed. The simplistic functionality of the software allows observations to be completed without supervision. ROCView can display images from multiple modalities, in a randomised order if required. Following registration, observers are prompted to begin their image evaluation. All data are recorded via mouse clicks, one to localise (mark) and one to score confidence (rate) using either an ordinal or continuous rating scale. Up to nine “mark-rating” pairs can be made per image. Unmarked images are given a default score of zero. Upon completion of the study, both true-positive and false-positive reports can be downloaded and adapted for analysis. ROCView has the potential to be a useful tool in the assessment of modality performance difference for a range of imaging methods.

Thompson, J; Hogg, P; Thompson, S; Manning, D; Szczepura, K

2012-01-01

436

Optical interferometric measurements of the static/dynamic response characteristics of MEMS ultrasonic transducers  

NASA Astrophysics Data System (ADS)

One of the most critical aspects of developing and optimizing capacitive micro-machined transducer systems involves the introduction of appropriate stress levels in the membrane structures during the manufacturing process. Subtle variations in the elastic modulus levels and mechanical coupling can dramatically alter the dynamic vibratory response of the MEMS for ultrasonic applications. In this effort, two different optical interferometric NDE approaches were used to evaluate the static and dynamic characteristics of individual MEMS elements in an ultrasonic transducer array system for variations of applied stress. The interferometric techniques provided a detailed microscopic characterization of the physical motions and local microscopic positions of the MEMS transducer membranes. It was found that the flexural response levels of individual MEMS membrane structures due to increased electrostatic forces was directly coupled to the dynamic response of the micro-transducer, and could potentially be used for optimizing the efficiency and dynamic motion extent of the MEMS transducer array. The optical interferometric techniques both proved to be valuable micro-NDE characterization tools, and were perfectly suited for characterizing the dynamic and static responses of the MEMS ultrasonic transducer systems.

Blackshire, James L.; Sathish, Shamachary

2003-07-01

437

Ground vibrations detection with fiber optic sensor  

NASA Astrophysics Data System (ADS)

In this paper, a fiber optic sensor based on fiber Bragg grating (FBG) is employed to measure the ground vibrations which may be generated by earthquakes, debris flows, landslides, and rock impacts on the ground. The detected vibration signals were analyzed by both fast Fourier transform (FFT) and Gabor transform to obtain the frequency response. The performance of fiber optic sensor was examined and compared with the conventional ground vibration geophone sensor. From the results of field tests, the fiber optic sensor shows highly similarity with conventional geophone sensor for low frequency measurement. The fiber optic vibration sensing system presented in this research is appropriate for sensing ground vibration in the frequency ranges of 10-250 Hz. The sensor proved to be an alternative option for ground vibrations monitoring system.

Liang, Tsair-Chun; Lin, Yung-Li

2012-05-01

438

Characteristic vibration patterns of odor compounds from bread-baking volatiles upon protein binding: density functional and ONIOM study and principal component analysis.  

PubMed

As the mechanism underlying the sense of smell is unclear, different models have been used to rationalize structure-odor relationships. To gain insight into odorant molecules from bread baking, binding energies and vibration spectra in the gas phase and in the protein environment [7-transmembrane helices (7TMHs) of rhodopsin] were calculated using density functional theory [B3LYP/6-311++G(d,p)] and ONIOM [B3LYP/6-311++G(d,p):PM3] methods. It was found that acetaldehyde ("acid" category) binds strongly in the large cavity inside the receptor, whereas 2-ethyl-3-methylpyrazine ("roasted") binds weakly. Lys296, Tyr268, Thr118 and Ala117 were identified as key residues in the binding site. More emphasis was placed on how vibrational frequencies are shifted and intensities modified in the receptor protein environment. Principal component analysis (PCA) suggested that the frequency shifts of C-C stretching, CH(3) umbrella, C = O stretching and CH(3) stretching modes have a significant effect on odor quality. In fact, the frequency shifts of the C-C stretching and C = O stretching modes, as well as CH(3) umbrella and CH(3) symmetric stretching modes, exhibit different behaviors in the PCA loadings plot. A large frequency shift in the CH(3) symmetric stretching mode is associated with the sweet-roasted odor category and separates this from the acid odor category. A large frequency shift of the C-C stretching mode describes the roasted and oily-popcorn odor categories, and separates these from the buttery and acid odor categories. PMID:21952829

Treesuwan, Witcha; Hirao, Hajime; Morokuma, Keiji; Hannongbua, Supa

2011-09-27

439

Analysis of Ripple Effects on Frequency Response Characteristics of Switching Regulators  

NASA Astrophysics Data System (ADS)

In this paper we clarify for the boost and the buck-boost converter that the ripple effect is not ignorable for the frequency response, and reveal that it causes the unexpected characteristics where either the phase lag or the phase lead appears depending on the shape of waveform of the ramp generator in the PWM circuit. Eventually the phase margin for the stability drastically changes depending on the slope direction (normal or reverse) of the sawtooth waveform of the ramp generator even in the same circuit configuration. For the ripple effects we propose the general analysis model and analyze them of the boost and the buck-boost converters. As the result we identify that the ripple effects are caused mainly by the variation of the slope and the average of the ripple, and reveal that the both converters have the asymmetric characteristics for the slope direction of the sawtooth waveform of the ramp generator and there is more advantage for the stability in case of the reverse slope direction than in case of the normal one. It also clarified that the effect of ESR of the output capacitor of the converter on the frequency response is different according to the shape of the sawtooth waveforms. The proposed analysis method is validated by the experiments and simulations.

Sakai, Eiji; Nakahara, Masatoshi

440

Influence of activated carbon characteristics on toluene and hexane adsorption: Application of surface response methodology  

NASA Astrophysics Data System (ADS)

The objective of this study was to evaluate the adsorption capacity of toluene and hexane over activated carbons prepared according an experimental design, considering as variables the activation temperature, the impregnation ratio and the activation time. The response surface methodology was applied to optimize the adsorption capacity of the carbons regarding the preparation conditions that determine the physicochemical characteristics of the activated carbons.The methodology of preparation produced activated carbons with surface areas and micropore volumes as high as 1128 m2/g and 0.52 cm3/g, respectively. Moreover, the activated carbons exhibit mesoporosity, ranging from 64.6% to 89.1% the percentage of microporosity. The surface chemistry was characterized by TPD, FTIR and acid–base titration obtaining different values of surface groups from the different techniques because the limitation of each technique, but obtaining similar trends for the activated carbons studied. The exhaustive characterization of the activated carbons allows to state that the measured surface area does not explain the adsorption capacity for either toluene or n-hexane. On the other hand, the surface chemistry does not explain the adsorption results either. A compromise between physical and chemical characteristics can be obtained from the appropriate activation conditions, and the response surface methodology gives the optimal activated carbon to maximize adsorption capacity. Low activation temperature, intermediate impregnation ratio lead to high toluene and n-hexane adsorption capacities depending on the activation time, which a determining factor to maximize toluene adsorption.

Izquierdo, Mª Teresa; de Yuso, Alicia Martínez; Valenciano, Raquel; Rubio, Begoña; Pino, Mª Rosa

2013-01-01

441

Surface Acoustic Wave (SAW) Vibration Sensors  

PubMed Central

In the paper a feasibility study on the use of surface acoustic wave (SAW) vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of a piezoelectric plate. Vibrations of the plate are transformed into electric signals that allow identification of the sensor and localization of a threat. The theoretical study of sensor vibrations leads us to the simple isotropic model with one degree of freedom. This model allowed an explicit description of the sensor plate movement and identification of the vibrating sensor. Analysis of frequency response of the ST-cut quartz sensor plate and a damping speed of its impulse response has been conducted. The analysis above was the basis to determine the ranges of parameters for vibrating plates to be useful in electronic warning systems. Generally, operation of electronic warning systems with SAW <