The development of sine vibration test requirements for Viking lander capsule components

NASA Technical Reports Server (NTRS)

Barrett, S.

1974-01-01

In connection with the Viking project for exploring the planet Mars, two identical spacecraft, each consisting of an orbiter and a lander, will be launched in the third quarter of 1975. Upon arrival at the planet, the Viking lander will separate from the Viking orbiter and descend to a soft landing at a selected site on the Mars surface. It was decided to perform a sine vibration test on the Viking spacecraft, in its launch configuration, to qualify it for the booster-induced transient-dynamic environment. It is shown that component-level testing is a cost- and schedule-effective prerequisite to the system-level, sine-vibration test sequences.

Plants respond to leaf vibrations caused by insect herbivore chewing.

PubMed

Appel, H M; Cocroft, R B

2014-08-01

Plant germination and growth can be influenced by sound, but the ecological significance of these responses is unclear. We asked whether acoustic energy generated by the feeding of insect herbivores was detected by plants. We report that the vibrations caused by insect feeding can elicit chemical defenses. Arabidopsis thaliana (L.) rosettes pre-treated with the vibrations caused by caterpillar feeding had higher levels of glucosinolate and anthocyanin defenses when subsequently fed upon by Pieris rapae (L.) caterpillars than did untreated plants. The plants also discriminated between the vibrations caused by chewing and those caused by wind or insect song. Plants thus respond to herbivore-generated vibrations in a selective and ecologically meaningful way. A vibration signaling pathway would complement the known signaling pathways that rely on volatile, electrical, or phloem-borne signals. We suggest that vibration may represent a new long distance signaling mechanism in plant-insect interactions that contributes to systemic induction of chemical defenses.

Vibration and Vibration-Torsion Levels of the S_{1} and Ground Cationic D_{0}^{+} States of Para-Fluorotoluene and Para-Xylene Below 1000 \\wn

NASA Astrophysics Data System (ADS)

Tuttle, William Duncan; Gardner, Adrian M.; Whalley, Laura E.; Wright, Timothy G.

2017-06-01

We have employed resonance-enhanced multiphoton ionisation (REMPI) spectroscopy and zero-kinetic-energy (ZEKE) spectroscopy to investigate the first excited electronic singlet (S_{1}) state and the cationic ground state (D_{0}^{+}) of para-fluorotoluene (pFT) and para-xylene (pXyl). Spectra have been recorded via a large number of selected intermediate levels, to support assignment of the vibration and vibration-torsion levels in these molecules and to investigate possible couplings. The study of levels in this region builds upon previous work on the lower energy regions of pFT and pXyl and here we are interested in how vibration-torsion (vibtor) levels might combine and interact with vibrational ones, and so we consider the possible couplings which occur. Comparisons between the spectra of the two molecules show a close correspondence, and the influence of the second methyl rotor in para-xylene on the onset of intramolecular vibrational redistribution (IVR) in the S_{1} state is a point of interest. This has bearing on future work which will need to consider the role of both more flexible side chains of substituted benzene molecules, and multiple side chains. A. M. Gardner, W. D. Tuttle, L. Whalley, A. Claydon, J. H. Carter and T. G. Wright, J. Chem. Phys., 145, 124307 (2016). A. M. Gardner, W. D. Tuttle, P. Groner and T. G. Wright, J. Chem. Phys., (2017, in press). W. D. Tuttle, A. M. Gardner, K. O'Regan, W. Malewicz and T. G. Wright, J. Chem. Phys., (2017, in press).

Resonant vibration control of rotating beams

NASA Astrophysics Data System (ADS)

Svendsen, Martin Nymann; Krenk, Steen; Høgsberg, Jan

2011-04-01

Rotating structures, like e.g. wind turbine blades, may be prone to vibrations associated with particular modes of vibration. It is demonstrated, how this type of vibrations can be reduced by using a collocated sensor-actuator system, governed by a resonant controller. The theory is here demonstrated by an active strut, connecting two cross-sections of a rotating beam. The structure is modeled by beam elements in a rotating frame of reference following the beam. The geometric stiffness is derived in a compact form from an initial stress formulation in terms of section forces and moments. The stiffness, and thereby the natural frequencies, of the beam depend on the rotation speed and the controller is tuned to current rotation speed to match the resonance frequency of the selected mode. It is demonstrated that resonant control leads to introduction of the intended level of damping in the selected mode and, with good modal connectivity, only very limited modal spill-over is generated. The controller acts by resonance and therefore has only a moderate energy consumption, and successfully reduces modal vibrations at the resonance frequency.

Ultrashort-pulse-train pump and dump excitation of a diatomic molecule

NASA Astrophysics Data System (ADS)

de Araujo, Luís E. E.

2010-09-01

An excitation scheme is proposed for transferring population between ground-vibrational levels of a molecule. The transfer is accomplished by pumping and dumping population with a pair of coherent ultrashort-pulse trains via a stationary state. By mismatching the teeth of the frequency combs associated with the pulse trains to the vibrational levels, high selectivity in the excitation, along with high transfer efficiency, is predicted. The pump-dump scheme does not suffer from spontaneous emission losses, it is insensitive to the pump-dump-train delay, and it requires only basic pulse shaping.

Ultrashort-pulse-train pump and dump excitation of a diatomic molecule

DOE Office of Scientific and Technical Information (OSTI.GOV)

Araujo, Luis E. E. de

An excitation scheme is proposed for transferring population between ground-vibrational levels of a molecule. The transfer is accomplished by pumping and dumping population with a pair of coherent ultrashort-pulse trains via a stationary state. By mismatching the teeth of the frequency combs associated with the pulse trains to the vibrational levels, high selectivity in the excitation, along with high transfer efficiency, is predicted. The pump-dump scheme does not suffer from spontaneous emission losses, it is insensitive to the pump-dump-train delay, and it requires only basic pulse shaping.

The comparison between the acquisition vibration data obtained by different types of transducers for hydraulic turbine head cover

NASA Astrophysics Data System (ADS)

Li, Youping; Lu, Jinsong; Cheng, Jian; Yin, Yongzhen; Wang, Jianlan

2017-04-01

Based on the summaries of the rules about the vibration measurement for hydro-generator sets with respect to relevant standards, the key issues of the vibration measurement, such as measurement modes, the transducer selection are illustrated. In addition, the problems existing in vibration measurement are pointed out. The actual acquisition data of head cover vertical vibration respectively obtained by seismic transducer and eddy current transducer in site hydraulic turbine performance tests during the rising of the reservoir upstream level in a certain hydraulic power plant are compared. The difference of the data obtained by the two types of transducers and the potential reasons are presented. The application conditions of seismic transducer and eddy current transducer for hydro-generator set vibration measurement are given based on the analysis. Research subjects that should be focused on about the topic discussed in this paper are suggested.

New approach for determination of the influence of long-range order and selected ring oscillations on IR spectra in zeolites.

PubMed

Mikuła, Andrzej; Król, Magdalena; Mozgawa, Włodzimierz; Koleżyński, Andrzej

2018-04-15

Vibrational spectroscopy can be considered as one of the most important methods used for structural characterization of various porous aluminosilicate materials, including zeolites. On the other hand, vibrational spectra of zeolites are still difficult to interpret, particularly in the pseudolattice region, where bands related to ring oscillations can be observed. Using combination of theoretical and computational approach, a detailed analysis of these regions of spectra is possible; such analysis should be, however, carried out employing models with different level of complexity and simultaneously the same theory level. In this work, an attempt was made to identify ring oscillations in vibrational spectra of selected zeolite structures. A series of ab initio calculations focused on S4R, S6R, and as a novelty, 5-1 isolated clusters, as well as periodic siliceous frameworks built from those building units (ferrierite (FER), mordenite (MOR) and heulandite (HEU) type) have been carried out. Due to the hierarchical structure of zeolite frameworks it can be expected that the total envelope of the zeolite spectra should be with good accuracy a sum of the spectra of structural elements that build each zeolite framework. Based on the results of HF calculations, normal vibrations have been visualized and detailed analysis of pseudolattice range of resulting theoretical spectra have been carried out. Obtained results have been applied for interpretation of experimental spectra of selected zeolites. Copyright © 2018 Elsevier B.V. All rights reserved.

Sympathetic Cooling of Molecular Ions in Selected Rotational and Vibrational States Produced by Threshold Photoionization

NASA Astrophysics Data System (ADS)

Tong, Xin; Winney, Alexander H.; Willitsch, Stefan

2010-10-01

We present a new method for the generation of rotationally and vibrationally state-selected, translationally cold molecular ions in ion traps. Our technique is based on the state-selective threshold photoionization of neutral molecules followed by sympathetic cooling of the resulting ions with laser-cooled calcium ions. Using N2+ ions as a test system, we achieve >90% selectivity in the preparation of the ground rovibrational level and state lifetimes on the order of 15 minutes limited by collisions with background-gas molecules. The technique can be employed to produce a wide range of apolar and polar molecular ions in the ground and excited rovibrational states. Our approach opens up new perspectives for cold quantum-controlled ion-molecule-collision studies, frequency-metrology experiments with state-selected molecular ions and molecular-ion qubits.

Selectivity in the inelastic rotational scattering of D2 and HD molecules from graphite: Similarities and differences respect to the H2 case

NASA Astrophysics Data System (ADS)

Rutigliano, Maria; Pirani, Fernando

2018-03-01

The inelastic scattering of D2 and HD molecules impinging on a graphite surface in well-defined initial roto-vibrational states has been studied by using the computational setup recently developed to characterize important selectivities in the molecular dynamics occurring at the gas-surface interface. In order to make an immediate comparison of determined elastic and inelastic scattering probabilities, we considered for D2 and HD molecules the same initial states, as well as the same collision energy range, previously selected for the investigation of H2 behaviour. The analysis of the back-scattered molecules shows that, while low-lying initial vibrational states are preserved, the medium-high initial ones give rise to final states covering the complete ladder of vibrational levels, although with different probability for the various cases investigated. Moreover, propensities in the formation of the final rotational states are found to depend strongly on the initial ones, on the collision energy, and on the isotopologue species.

A spectroscopist's view of energy states, energy transfers, and chemical reactions.

PubMed

Moore, C Bradley

2007-01-01

This chapter describes a research career beginning at Berkeley in 1960, shortly after Sputnik and the invention of the laser. Following thesis work on vibrational spectroscopy and the chemical reactivity of small molecules, we studied vibrational energy transfers in my own lab. Collision-induced transfers among vibrations of a single molecule, from one molecule to another, and from vibration to rotation and translation were elucidated. My research group also studied the competition between vibrational relaxation and chemical reaction for potentially reactive collisions with one molecule vibrationally excited. Lasers were used to enrich isotopes by the excitation of a predissociative transition of a selected isotopomer. We also tested the hypotheses of transition-state theory for unimolecular reactions of ketene, formaldehyde, and formyl fluoride by (a) resolving individual molecular eigenstates above a dissociation threshold, (b) locating vibrational levels at the transition state, (c) observing quantum resonances in the barrier region for motion along a reaction coordinate, and (d) studying energy release to fragments.

Technique for Increasing the Selectivity of the Method of Laser Fragmentation/Laser-Induced Fluorescence

NASA Astrophysics Data System (ADS)

Bobrovnikov, S. M.; Gorlov, E. V.; Zharkov, V. I.

2018-05-01

A technique for increasing the selectivity of the method of detecting high-energy materials (HEMs) based on laser fragmentation of HEM molecules with subsequent laser excitation of fluorescence of the characteristic NO fragments from the first vibrational level of the ground state is suggested.

Kinetic model for the vibrational energy exchange in flowing molecular gas mixtures. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Offenhaeuser, F.

1987-01-01

The present study is concerned with the development of a computational model for the description of the vibrational energy exchange in flowing gas mixtures, taking into account a given number of energy levels for each vibrational degree of freedom. It is possible to select an arbitrary number of energy levels. The presented model uses values in the range from 10 to approximately 40. The distribution of energy with respect to these levels can differ from the equilibrium distribution. The kinetic model developed can be employed for arbitrary gaseous mixtures with an arbitrary number of vibrational degrees of freedom for each type of gas. The application of the model to CO2-H2ON2-O2-He mixtures is discussed. The obtained relations can be utilized in a study of the suitability of radiation-related transitional processes, involving the CO2 molecule, for laser applications. It is found that the computational results provided by the model agree very well with experimental data obtained for a CO2 laser. Possibilities for the activation of a 16-micron and 14-micron laser are considered.

Characterization of spacecraft and environmental disturbances on a SmallSat

NASA Technical Reports Server (NTRS)

Johnson, Thomas A.; Nguyen, Dung Phu Chi; Cuda, Vince; Freesland, Doug

1994-01-01

The objective of this study is to model the on-orbit vibration environment encountered by a SmallSat. Vibration control issues are common to the Earth observing, imaging, and microgravity communities. A spacecraft may contain dozens of support systems and instruments each a potential source of vibration. The quality of payload data depends on constraining vibration so that parasitic disturbances do not affect the payload's pointing or microgravity requirement. In practice, payloads are designed incorporating existing flight hardware in many cases with nonspecific vibration performance. Thus, for the development of a payload, designers require a thorough knowledge of existing mechanical devices and their associated disturbance levels. This study evaluates a SmallSat mission and seeks to answer basic questions concerning on-orbit vibration. Payloads were considered from the Earth observing, microgravity, and imaging communities. Candidate payload requirements were matched to spacecraft bus resources of present day SmallSats. From the set of candidate payloads, the representative payload GLAS (Geoscience Laser Altimeter System) was selected. The requirements of GLAS were considered very stringent for the 150 - 500 kg class of payloads. Once the payload was selected, a generic SmallSat was designed in order to accommodate the payload requirements (weight, size, power, etc.). This study seeks to characterize the on-orbit vibration environment of a SmallSat designed for this type of mission and to determine whether a SmallSat can provide the precision pointing and jitter control required for earth observing payloads.

Influence of Type of Frequency Weighting Function On VDV Analysis

NASA Astrophysics Data System (ADS)

Kowalska-Koczwara, Alicja; Stypuła, Krzysztof

2017-10-01

Transport vibrations are the subject of many research, mostly their influence on structural elements of the building is investigated. However, nowadays, especially in the centres of large cities were apartments, residential buildings are closer to the transport vibration sources, an increasing attention is given to providing vibrational comfort to humans in buildings. Currently, in most countries, two main methods of evaluation are used: root mean squared method (RMS) and vibration dose value (VDV). In this article, VDV method is presented and the analysis of the weighting functions selection on value of VDV is made. Measurements required for the analysis were made in Krakow, on masonry, residential, two storey building located in the city centre. The building is subjected into two transport vibration sources: tram passages and vehicle passages on very close located road. Measurement points were located on the basement wall at ground level to control the excitation and in the middle of the floor on the highest storey (in the place where people percept vibration). The room chosen for measurements is located closest to the transport excitation sources. During the measurements, 25 vibration events were recorded and analysed. VDV values were calculated for three different weighting functions according to standard: ISO 2631-1, ISO 2631-2 and BS-6841. Differences in VDV values are shown, but also influence of the weighting function selection on result of evaluation is also presented. VDV analysis was performed not only for the individual vibration event but also all day and night vibration exposure were calculated using formulas contained in the annex to the standard BS-6841. It is demonstrated that, although there are differences in the values of VDV, an influence on all day and night exposure is no longer so significant.

Dynamic Characteristics of Buildings from Signal Processing of Ambient Vibration

NASA Astrophysics Data System (ADS)

Dobre, Daniela; Sorin Dragomir, Claudiu

2017-10-01

The experimental technique used to determine the dynamic characteristics of buildings is based on records of low intensity oscillations of the building produced by various natural factors, such as permanent agitation type microseismic motions, city traffic, wind etc. The possibility of recording these oscillations is provided by the latest seismic stations (Geosig and Kinemetrics digital accelerographs). The permanent microseismic agitation of the soil is a complex form of stationary random oscillations. The building filters the soil excitation, selects and increases the components of disruptive vibrations corresponding to its natural vibration periods. For some selected buildings, with different instrumentation schemes for the location of sensors (in free-field, at basement, ground floor, roof level), a correlation between the dynamic characteristics resulted from signal processing of ambient vibration and from a theoretical analysis will be presented. The interpretation of recording results could highlight the behavior of the whole structure. On the other hand, these results are compared with those from strong motions, or obtained from a complex dynamic analysis, and they are quite different, but they are explicable.

Analysis of Design Parameters Effects on Vibration Characteristics of Fluidlastic Isolators

NASA Astrophysics Data System (ADS)

Deng, Jing-hui; Cheng, Qi-you

2017-07-01

The control of vibration in helicopters which consists of reducing vibration levels below the acceptable limit is one of the key problems. The fluidlastic isolators become more and more widely used because the fluids are non-toxic, non-corrosive, nonflammable, and compatible with most elastomers and adhesives. In the field of the fluidlastic isolators design, the selection of design parameters is very important to obtain efficient vibration-suppressed. Aiming at getting the effect of design parameters on the property of fluidlastic isolator, a dynamic equation is set up based on the theory of dynamics. And the dynamic analysis is carried out. The influences of design parameters on the property of fluidlastic isolator are calculated. Dynamic analysis results have shown that fluidlastic isolator can reduce the vibration effectively. Analysis results also showed that the design parameters such as the fluid density, viscosity coefficient, stiffness (K1 and K2) and loss coefficient have obvious influence on the performance of isolator. The efficient vibration-suppressed can be obtained by the design optimization of parameters.

Effects of whole body vibration on muscle spasticity for people with central nervous system disorders: a systematic review.

PubMed

Huang, Meizhen; Liao, Lin-Rong; Pang, Marco Yc

2017-01-01

To examine the effects of whole-body vibration on spasticity among people with central nervous system disorders. Electronic searches were conducted using CINAHL, Cochrane Library, MEDLINE, Physiotherapy Evidence Database, PubMed, PsycINFO, SPORTDiscus and Scopus to identify randomized controlled trials that investigated the effect of whole-body vibration on spasticity among people with central nervous system disorders (last search in August 2015). The methodological quality and level of evidence were rated using the PEDro scale and guidelines set by the Oxford Centre for Evidence-Based Medicine. Nine trials with totally 266 subjects (three in cerebral palsy, one in multiple sclerosis, one in spinocerebellar ataxia, and four in stroke) fulfilled all selection criteria. One study was level 1b (PEDro⩾6 and sample size>50) and eight were level 2b (PEDro<6 or sample size ⩽50). All three cerebral palsy trials (level 2b) reported some beneficial effects of whole-body vibration on reducing leg muscle spasticity. Otherwise, the results revealed no consistent benefits on spasticity in other neurological conditions studied. There is little evidence that change in spasticity was related to change in functional performance. The optimal protocol could not be identified. Many reviewed studies were limited by weak methodological and reporting quality. Adverse events were minor and rare. Whole-body vibration may be useful in reducing leg muscle spasticity in cerebral palsy but this needs to be verified by future high quality trials. There is insufficient evidence to support or refute the notion that whole-body vibration can reduce spasticity in stroke, spinocerebellar ataxia or multiple sclerosis.

Selective bond breaking mediated by state specific vibrational excitation in model HOD molecule through optimized femtosecond IR pulse: a simulated annealing based approach.

PubMed

Shandilya, Bhavesh K; Sen, Shrabani; Sahoo, Tapas; Talukder, Srijeeta; Chaudhury, Pinaki; Adhikari, Satrajit

2013-07-21

The selective control of O-H/O-D bond dissociation in reduced dimensionality model of HOD molecule has been explored through IR+UV femtosecond pulses. The IR pulse has been optimized using simulated annealing stochastic approach to maximize population of a desired low quanta vibrational state. Since those vibrational wavefunctions of the ground electronic states are preferentially localized either along the O-H or O-D mode, the femtosecond UV pulse is used only to transfer vibrationally excited molecule to the repulsive upper surface to cleave specific bond, O-H or O-D. While transferring from the ground electronic state to the repulsive one, the optimization of the UV pulse is not necessarily required except specific case. The results so obtained are analyzed with respect to time integrated flux along with contours of time evolution of probability density on excited potential energy surface. After preferential excitation from [line]0, 0> ([line]m, n> stands for the state having m and n quanta of excitations in O-H and O-D mode, respectively) vibrational level of the ground electronic state to its specific low quanta vibrational state ([line]1, 0> or [line]0, 1> or [line]2, 0> or [line]0, 2>) by using optimized IR pulse, the dissociation of O-D or O-H bond through the excited potential energy surface by UV laser pulse appears quite high namely, 88% (O-H ; [line]1, 0>) or 58% (O-D ; [line]0, 1>) or 85% (O-H ; [line]2, 0>) or 59% (O-D ; [line]0, 2>). Such selectivity of the bond breaking by UV pulse (if required, optimized) together with optimized IR one is encouraging compared to the normal pulses.

Neuronal Regression of Internal Leg Vibroreceptor Organs in a Cave-Dwelling Insect (Orthoptera: Rhaphidophoridae: Dolichopoda araneiformis).

PubMed

Strauß, Johannes; Stritih, Nataša

2017-01-01

Animals' adaptations to cave habitats generally include elaboration of extraoptic senses, and in insects the receptor structures located on the legs are supposed to become more prominent in response to constant darkness. The receptors for detecting substrate vibrations are often highly sensitive scolopidial sensilla localized within the legs or the body. For troglobitic insects the evolutionary changes in vibroreceptor organs have not been studied. Since rock is an extremely unfavorable medium for vibration transmission, selection on vibration receptors may be weakened in caves, and these sensory organs may undergo regressive evolution. We investigated the anatomy of the most elaborate internal vibration detection system in orthopteroid insects, the scolopidial subgenual organ complex in the cave cricket Dolichopoda araneiformis (Orthoptera: Ensifera: Rhaphidophoridae). This is a suitable model species which shows high levels of adaptation to cave life in terms of both phenotypic and life cycle characteristics. We compared our data with data on the anatomy and physiology of the subgenual organ complex from the related troglophilic species Troglophilus neglectus. In D. araneiformis, the subgenual organ complex contains three scolopidial organs: the subgenual organ, the intermediate organ, and the accessory organ. The presence of individual organs and their innervation pattern are identical to those found in T. neglectus, while the subgenual organ and the accessory organ of D. araneiformis contain about 50% fewer scolopidial sensilla than in T. neglectus. This suggests neuronal regression of these organs in D. araneiformis, which may reflect a relaxed selection pressure for vibration detection in caves. At the same time, a high level of overall neuroanatomical conservation of the intermediate organ in this species suggests persistence of the selection pressure maintaining this particular organ. While regressive evolution of chordotonal organs has been documented for insect auditory organs, this study shows for the first time that internal vibroreceptors can also be affected. © 2017 S. Karger AG, Basel.

Correlation study between vibrational environmental and failure rates of civil helicopter components

NASA Technical Reports Server (NTRS)

Alaniz, O.

1979-01-01

An investigation of two selected helicopter types, namely, the Models 206A/B and 212, is reported. An analysis of the available vibration and reliability data for these two helicopter types resulted in the selection of ten components located in five different areas of the helicopter and consisting primarily of instruments, electrical components, and other noncritical flight hardware. The potential for advanced technology in suppressing vibration in helicopters was assessed. The are still several unknowns concerning both the vibration environment and the reliability of helicopter noncritical flight components. Vibration data for the selected components were either insufficient or inappropriate. The maintenance data examined for the selected components were inappropriate due to variations in failure mode identification, inconsistent reporting, or inaccurate informaton.

Effects of Frequency and Acceleration Amplitude on Osteoblast Mechanical Vibration Responses: A Finite Element Study

PubMed Central

Hsu, Hung-Yao

2016-01-01

Bone cells are deformed according to mechanical stimulation they receive and their mechanical characteristics. However, how osteoblasts are affected by mechanical vibration frequency and acceleration amplitude remains unclear. By developing 3D osteoblast finite element (FE) models, this study investigated the effect of cell shapes on vibration characteristics and effect of acceleration (vibration intensity) on vibrational responses of cultured osteoblasts. Firstly, the developed FE models predicted natural frequencies of osteoblasts within 6.85–48.69 Hz. Then, three different levels of acceleration of base excitation were selected (0.5, 1, and 2 g) to simulate vibrational responses, and acceleration of base excitation was found to have no influence on natural frequencies of osteoblasts. However, vibration response values of displacement, stress, and strain increased with the increase of acceleration. Finally, stress and stress distributions of osteoblast models under 0.5 g acceleration in Z-direction were investigated further. It was revealed that resonance frequencies can be a monotonic function of cell height or bottom area when cell volumes and material properties were assumed as constants. These findings will be useful in understanding how forces are transferred and influence osteoblast mechanical responses during vibrations and in providing guidance for cell culture and external vibration loading in experimental and clinical osteogenesis studies. PMID:28074178

Methods for the quantification of pseudo-vibration sensitivities in laser vibrometry

NASA Astrophysics Data System (ADS)

Martin, P.; Rothberg, S. J.

2011-03-01

Pseudo-vibration sensitivities in laser vibrometry are the consequence of measurement noise generated by surface motions other than that on-axis with the incident laser beam(s), such as transverse and tilt vibrations or rotation. On rougher surfaces, laser speckle is the cause but similar noise is observed in measurements from smoother surfaces. This paper's principal aim is to introduce two experimental methods for quantification, including dedicated data processing, to deliver sensitivities in three forms: a spectral map, a mean level per order and a total rms level. Single and parallel beam vibrometers and different surface roughness or treatment are accommodated, with sensitivities presented for two commercial instruments (beam diameters 90 and 520 µm). For transverse sensitivity, a total rms level around 0.05% is found for the larger beam, a quarter of the level for the smaller beam. For tilt sensitivity, advantage shifts to the smaller beam with a total rms level around 0.45 µm s-1/deg s-1, less than one-third of that for the larger beam. Levels hold fairly constant across the rougher surfaces, reducing only for a polished surface. For rotation sensitivities (radial vibrations), advantage remains with the smaller beam with a total rms level around 2 µm s-1/deg s-1, compared to 5 µm s-1/deg s-1 for the larger beam, while sensitivity reduces with diminishing roughness. These sensitivities are especially valuable to vibrometer users in instrumentation selection and data analysis.

Simulating Energy Relaxation in Pump-Probe Vibrational Spectroscopy of Hydrogen-Bonded Liquids.

PubMed

Dettori, Riccardo; Ceriotti, Michele; Hunger, Johannes; Melis, Claudio; Colombo, Luciano; Donadio, Davide

2017-03-14

We introduce a nonequilibrium molecular dynamics simulation approach, based on the generalized Langevin equation, to study vibrational energy relaxation in pump-probe spectroscopy. A colored noise thermostat is used to selectively excite a set of vibrational modes, leaving the other modes nearly unperturbed, to mimic the effect of a monochromatic laser pump. Energy relaxation is probed by analyzing the evolution of the system after excitation in the microcanonical ensemble, thus providing direct information about the energy redistribution paths at the molecular level and their time scale. The method is applied to hydrogen-bonded molecular liquids, specifically deuterated methanol and water, providing a robust picture of energy relaxation at the molecular scale.

Vibration syndrome in Forestry Commission chain saw operators

PubMed Central

Taylor, W.; Pearson, J.; Kell, R. L.; Keighley, G. D.

1971-01-01

Taylor, W., Pearson, J., Kell, R. L., and Keighley, G. D. (1971). Brit. J. industr. Med., 28, 83-89. Vibration syndrome in Forestry Commission chain saw operators. A preliminary investigation has been made into the prevalence of the vibration syndrome in the employees of the Forestry Commission (Britain). A questionnaire covered 20 randomly selected employees for each of 40 forests chosen at random, giving a total sample of 800 out of 9 600 employees. Of the 756 employees still with the Forestry Commission, 732 responded (97%). The analyses were confined to the 711 male employees, of whom 142 were chain saw operators. In this number, the prevalence of the vibration syndrome was 44% whereas in men who did not handle the chain saw the prevalence was significantly lower at 18% (0·005 level of significance). A regional difference was found. South England showed the highest rate at 69% compared with North England at 31% and Scotland at 33%. An increase in prevalence with years of chain saw usage was found, starting at around two years with a marked increase (73%) at over eight years. In part, this effect explains the regional differences. Men with the syndrome were significantly more affected by chilling at work, during rest periods, and while sheltering from bad weather, with blanching of the fingers (89%) most affected by the weather, followed by sensory loss (84%). During the survey vibration levels were measured on 18 chain saws. The major vibration component from each saw fell within the 125 Hz octave band and the vibration levels considerably exceeded the criterion of Axelsson (1968). In 16 of the saws the amplitudes were greater on the lower (trigger) handle. PMID:5543631

Mesospheric nightglow spectral survey taken by the ISO spectral spatial imager on ATLAS 1

NASA Technical Reports Server (NTRS)

Owens, J. K.; Torr, D. G.; Torr, M. R.; Chang, T.; Fennelly, J. A.; Richards, P. G.; Morgan, M. F.; Baldridge, T. W.; Fellows, C. W.; Dougani, H.

1993-01-01

This paper reports the first comprehensive spectral survey of the mesospheric airglow between 260 and 832 nm taken by the Imaging Spectrometric Observatory on the ATLAS 1 mission. We select data taken in the spectral window between 275 and 300 nm to determine the variation with altitude of the Herzberg I bands originating from the vibrational levels v-prime = 3 to 8. These data provide the first spatially resolved spectral measurements of the system. The data are used to demonstrate that to within an uncertainty of +/- 10 percent, the vibrational distribution remains invariant with altitude. The deficit reported previously for the v-prime = 5 level is not observed although there is a suggestion of depletion in v-prime = 6. The data could be used to place tight constraints on the vibrational dependence of quenching rate coefficients, and on the abundance of atomic oxygen.

Mesospheric nightglow spectral survey taken by the ISO spectral spatial imager on Atlas 1

NASA Technical Reports Server (NTRS)

Owens, J. K.; Torr, D. G.; Torr, M. R.; Chang, T.; Fennelly, J. A.; Richards, P. G.; Morgan, M. F.; Baldridge, T. W.; Dougani, H.; Swift, W.

1993-01-01

This paper reports the first comprehensive spectral survey of the mesospheric airglow between 260 and 832 nm taken by the Imaging Spectrometric Observatory (ISO) on the ATLAS I mission. We select data taken in the spectral window between 275 and 300 nm to determine the variation with altitude of the Herzberg I bands originating from the vibrational levels v' = 3 to 8. These data provide the first spatially resolved spectral measurements of the system. The data are used to demonstrate that to within an uncertainty of + 10%, the vibrational distribution remains invariant with altitude. The deficit reported previously for the v' = 5 level is not observed although there is a suggestion of depletion in v' = 6. The data could be used to place tight constraints on the vibrational dependence of quenching rate coefficients, and on the abundance of atomic oxygen.

A Fatigue Measuring Protocol for Wireless Body Area Sensor Networks.

PubMed

Akram, Sana; Javaid, Nadeem; Ahmad, Ashfaq; Khan, Zahoor Ali; Imran, Muhammad; Guizani, Mohsen; Hayat, Amir; Ilahi, Manzoor

2015-12-01

As players and soldiers preform strenuous exercises and do difficult and tiring duties, they are usually the common victims of muscular fatigue. Keeping this in mind, we propose FAtigue MEasurement (FAME) protocol for soccer players and soldiers using in-vivo sensors for Wireless Body Area Sensor Networks (WBASNs). In FAME, we introduce a composite parameter for fatigue measurement by setting a threshold level for each sensor. Whenever, any sensed data exceeds its threshold level, the players or soldiers are declared to be in a state of fatigue. Moreover, we use a vibration pad for the relaxation of fatigued muscles, and then utilize the vibrational energy by means of vibration detection circuit to recharge the in-vivo sensors. The induction circuit achieves about 68 % link efficiency. Simulation results show better performance of the proposed FAME protocol, in the chosen scenarios, as compared to an existing Wireless Soccer Team Monitoring (WSTM) protocol in terms of the selected metrics.

Two-mode elliptical-core weighted fiber sensors for vibration analysis

NASA Technical Reports Server (NTRS)

Vengsarkar, Ashish M.; Murphy, Kent A.; Fogg, Brian R.; Miller, William V.; Greene, Jonathan A.; Claus, Richard O.

1992-01-01

Two-mode, elliptical-core optical fibers are demonstrated in weighted, distributed and selective vibration-mode-filtering applications. We show how appropriate placement of optical fibers on a vibrating structure can lead to vibration mode filtering. Selective vibration-mode suppression on the order of 10 dB has been obtained using tapered two-mode, circular-core fibers with tapering functions that match the second derivatives of the modes of vibration to be enhanced. We also demonstrate the use of chirped, two-mode gratings in fibers as spatial modal sensors that are equivalents of shaped piezoelectric sensors.

The effect of the intermolecular potential formulation on the state-selected energy exchange rate coefficients in N2-N2 collisions.

PubMed

Kurnosov, Alexander; Cacciatore, Mario; Laganà, Antonio; Pirani, Fernando; Bartolomei, Massimiliano; Garcia, Ernesto

2014-04-05

The rate coefficients for N2-N2 collision-induced vibrational energy exchange (important for the enhancement of several modern innovative technologies) have been computed over a wide range of temperature. Potential energy surfaces based on different formulations of the intramolecular and intermolecular components of the interaction have been used to compute quasiclassically and semiclassically some vibrational to vibrational energy transfer rate coefficients. Related outcomes have been rationalized in terms of state-to-state probabilities and cross sections for quasi-resonant transitions and deexcitations from the first excited vibrational level (for which experimental information are available). On this ground, it has been possible to spot critical differences on the vibrational energy exchange mechanisms supported by the different surfaces (mainly by their intermolecular components) in the low collision energy regime, though still effective for temperatures as high as 10,000 K. It was found, in particular, that the most recently proposed intermolecular potential becomes the most effective in promoting vibrational energy exchange near threshold temperatures and has a behavior opposite to the previously proposed one when varying the coupling of vibration with the other degrees of freedom. Copyright © 2014 Wiley Periodicals, Inc.

Laboratory and field measurements and evaluations of vibration at the handles of riveting hammers

PubMed Central

McDOWELL, THOMAS W.; WARREN, CHRISTOPHER; WELCOME, DANIEL E.; DONG, REN G.

2015-01-01

The use of riveting hammers can expose workers to harmful levels of hand-transmitted vibration (HTV). As a part of efforts to reduce HTV exposures through tool selection, the primary objective of this study was to evaluate the applicability of a standardized laboratory-based riveting hammer assessment protocol for screening riveting hammers. The second objective was to characterize the vibration emissions of reduced vibration riveting hammers and to make approximations of the HTV exposures of workers operating these tools in actual work tasks. Eight pneumatic riveting hammers were selected for the study. They were first assessed in a laboratory using the standardized method for measuring vibration emissions at the tool handle. The tools were then further assessed under actual working conditions during three aircraft sheet metal riveting tasks. Although the average vibration magnitudes of the riveting hammers measured in the laboratory test were considerably different from those measured in the field study, the rank orders of the tools determined via these tests were fairly consistent, especially for the lower vibration tools. This study identified four tools that consistently exhibited lower frequency-weighted and unweighted accelerations in both the laboratory and workplace evaluations. These observations suggest that the standardized riveting hammer test is acceptable for identifying tools that could be expected to exhibit lower vibrations in workplace environments. However, the large differences between the accelerations measured in the laboratory and field suggest that the standardized laboratory-based tool assessment is not suitable for estimating workplace riveting hammer HTV exposures. Based on the frequency-weighted accelerations measured at the tool handles during the three work tasks, the sheet metal mechanics assigned to these tasks at the studied workplace are unlikely to exceed the daily vibration exposure action value (2.5 m s−2) using any of the evaluated riveting hammers. PMID:22539561

Compact and lightweight support platform with electromagnetic disturbance elimination for interferometer on reversed field pinch Keda Torus eXperiment

NASA Astrophysics Data System (ADS)

Mao, Wenzhe; Yuan, Peng; Zheng, Jian; Ding, Weixing; Li, Hong; Lan, Tao; Liu, Adi; Liu, Wandong; Xie, Jinlin

2016-11-01

A compact and lightweight support platform has been used as a holder for the interferometer system on the Keda Torus eXperiment (KTX), which is a reversed field pinch device. The vibration caused by the interaction between the time-varying magnetic field and the induced current driven in the metal optical components has been measured and, following comparison with the mechanical vibration of the KTX device and the refraction effect of the ambient turbulent air flow, has been identified as the primary vibration source in this case. To eliminate this electromagnetic disturbance, nonmetallic epoxy resin has been selected as the material for the support platform and the commercially available metal optical mounts are replaced. Following these optimization steps and mechanical reinforcements, the stability of the interferometer platform has improved significantly. The phase shift caused by the vibration has been reduced to the level of background noise.

Intramolecular Vibrational Energy Redistribution (ivr) in Selected S_{1} Levels above 1000 cm^{-1} in Para-Fluorotoluene

NASA Astrophysics Data System (ADS)

Whalley, Laura E.; Gardner, Adrian M.; Tuttle, William Duncan; Davies, Julia A.; Reid, Katharine L.; Wright, Timothy G.

2017-06-01

With increasing vibrational wavenumber, the density of states of a molecule is expected to rise dramatically, especially so when low wavenumber torsions (internal rotations) are present, as in the case of para-fluorotoluene (pFT). This in turn is expected to lead to more opportunities for coupling between vibrational modes, which is the driving force for intramolecular vibrational energy redistribution (IVR). Previous studies at higher energies have focussed on the two close lying vibrational levels at 1200 cm^{-1} in the S_{1} electronic state of pFT which were assigned to two zero-order bright states (ZOBSs), whose characters predominantly involve C-CH_{3} and C-F stretching modes. A surprising result of these studies was that the photoelectron spectra showed evidence that IVR is more extensive following excitation of the C-F mode than it is following excitation of the C-CH_{3} mode, despite these levels being separated by only 35 cm^{-1}. This observation provides evidence that the IVR dynamics are mode-specific, which in turn may be a consequence of the IVR route being dependent on couplings to nearby states that are only available to the C-F mode. In this work, in order to further investigate this behaviour, we have employed resonance-enhanced multiphoton ionisation (REMPI) spectroscopy and zero-kinetic-energy (ZEKE) spectroscopy to probe S_{1} levels above 1000 cm^{-1} in pFT. Such ZEKE spectra have been recorded via a number of S_{1} intermediate levels allowing the character and coupling between vibrations to be unravelled; the consequence of this coupling will be discussed with a view to understanding any IVR dynamics seen. C. J. Hammond, V. L. Ayles, D. E. Bergeron, K. L. Reid and T. G. Wright, J. Chem. Phys., 125, 124308 (2006) J. A. Davies, A. M. Green, A. M. Gardner, C. D. Withers, T. G. Wright and K. L. Reid, Phys. Chem. Chem. Phys., 16, 430 (2014)

Fourth-Order Vibrational Transition State Theory and Chemical Kinetics

NASA Astrophysics Data System (ADS)

Stanton, John F.; Matthews, Devin A.; Gong, Justin Z.

2015-06-01

Second-order vibrational perturbation theory (VPT2) is an enormously successful and well-established theory for treating anharmonic effects on the vibrational levels of semi-rigid molecules. Partially as a consequence of the fact that the theory is exact for the Morse potential (which provides an appropriate qualitative model for stretching anharmonicity), VPT2 calculations for such systems with appropriate ab initio potential functions tend to give fundamental and overtone levels that fall within a handful of wavenumbers of experimentally measured positions. As a consequence, the next non-vanishing level of perturbation theory -- VPT4 -- offers only slight improvements over VPT2 and is not practical for most calculations since it requires information about force constants up through sextic. However, VPT4 (as well as VPT2) can be used for other applications such as the next vibrational correction to rotational constants (the ``gammas'') and other spectroscopic parameters. In addition, the marriage of VPT with the semi-classical transition state theory of Miller (SCTST) has recently proven to be a powerful and accurate treatment for chemical kinetics. In this talk, VPT4-based SCTST tunneling probabilities and cumulative reaction probabilities are give for the first time for selected low-dimensional model systems. The prospects for VPT4, both practical and intrinsic, will also be discussed.

Subjective scaling of hand-arm vibration.

PubMed

Maeda, Setsuo; Shibata, Nobuyuki

2008-04-01

The purpose of this research was to establish a scale for comfort with regard to hand-arm vibration using the category judgment method and to validate the frequency-weighting method of the ISO 5349-1 standard. Experiments were conducted using random signals as stimuli. These stimuli consisted of three types of signal, namely designated stimulus F, with flat power spectrum density (PSD) ranging from 1 to 1,000 Hz, stimulus H with PSD which became 20 dB higher at 1,000 Hz than at 1 Hz, and stimulus L that had a PSD 20 dB lower at 1,000 Hz. These stimuli were selected from the specific spectrum patterns of hand-held vibration tools. These signals were modified by the Wh frequency weighting in accordance with ISO 5349-1, and the R.M.S. values were adjusted to be equal. In addition, the signal levels were varied over a range of five steps to create 15 kinds of individual stimuli. The subjects sat in front of a vibrator and grasped the mounted handle which exposed them to vertical vibrations after which they were asked to choose a numerical category to best indicate their perceived level of comfort (or otherwise) during each stimulus. From the experimental results of the category judgment method, the relationship between the psychological values and the frequency-weighted R.M.S. acceleration according to the ISO 5349-1 standard was obtained. It was found that the subjective response scaling of hand-arm vibration can be used for design-objective values of hand-held tool vibration.

Concorde noise-induced building vibrations: John F. Kennedy International Airport

NASA Technical Reports Server (NTRS)

Mayes, W. H.; Stephens, D. G.; Deloach, R.; Cawthorn, J. M.; Holmes, H. K.; Lewis, R. B.; Holliday, B. G.; Ward, D. W.; Miller, W. T.

1978-01-01

Outdoor and indoor noise levels resulting from aircraft flyovers and certain nonaircraft events were recorded at eight homesites and a school along with the associated vibration levels in the walls, windows, and floors at these test sites. Limited subjective tests were conducted to examine the human detection and annoyance thresholds for building vibration and rattle caused by aircraft noise. Both vibration and rattle were detected subjectively in several houses for some operations of both the Concorde and subsonic aircraft. Seated subjects more readily detected floor vibrations than wall or window vibrations. Aircraft noise generally caused more window vibrations than common nonaircraft events such as walking and closing doors. Nonaircraft events and aircraft flyovers resulted in comparable wall vibration levels, while floor vibrations were generally greater for nonaircraft events than for aircraft flyovers. The relationship between structural vibration and aircraft noise is linear, with vibration levels being accurately predicted from overall sound pressure levels (OASPL) measured near the structure. Relatively high levels of structural vibration measured during Concorde operations are due more to higher OASPL levels than to unique Concorde-source characteristics.

The choice of boundary conditions and mesh for scaffolding FEM model on the basis of natural vibrations measurements

NASA Astrophysics Data System (ADS)

Cyniak, Patrycja; Błazik-Borowa, Ewa; Szer, Jacek; Lipecki, Tomasz; Szer, Iwona

2018-01-01

Scaffolding is a specific construction with high susceptibility to low frequency vibrations. The numerical model of scaffolding presented in this paper contains real imperfections received from geodetic measurements of real construction. Boundary conditions were verified on the basis of measured free vibrations. A simulation of a man walking on penultimate working level as a dynamic load variable in time was made for verified model. The paper presents procedure for a choice of selected parameters of the scaffolding FEM model. The main aim of analysis is the best projection of the real construction and correct modeling of worker walking on the scaffolding. Different boundary conditions are considered, because of their impact on construction vibrations. Natural vibrations obtained from FEM calculations are compared with free vibrations measured during in-situ tests. Structure accelerations caused by walking human are then considered in this paper. Methodology of creating numerical models of scaffoldings and analysis of dynamic effects during human walking are starting points for further considerations about dynamic loads acting on such structures and effects of these loads to construction and workers, whose workplaces are situated on the scaffolding.

Evaluation of reaction time performance and subjective drowsiness during whole-body vibration exposure

NASA Astrophysics Data System (ADS)

Azizan, A.; Zali, Z.; Padil, H.

2018-05-01

Despite the automotive industry’s interest in how vibration affects the level of human comfort, there is little focus on the effect of vibration on drowsiness level. Thus, this study involves eighteen healthy male participants to study the effect of exposure to vibration on the drowsiness level. Prior to the experiment, the total transmitted vibration measured at interfaces between the seat pan and seat back to the human body for each participant was modified to become 0.2 ms-2 r.m.s and 0.4 ms-2 r.m.s. During the experiment, the participants were seated and exposed to 20-minutes of Gaussian random vibration with frequency band 1-15 Hz at two level of amplitude (low vibration amplitude and medium vibration amplitude) on separate days. The level of drowsiness was measured using a PVT test prior and after exposure to the vibration while participants rated their subjective drowsiness by using the Karolinska Sleepiness Scale (KSS). The significant increase in the number of lapse and reaction time because of the exposure to vibration in both conditions provide strong evidence of drowsiness. In this regard, the medium vibration amplitude shows a more prominent effect. All participants have shown a steady increase of drowsiness level in KSS. Meanwhile, there are no significant differences found between low vibration amplitude and medium vibration amplitude in the KSS. These findings suggest that human alertness level is greatly affected by the exposure to vibration and these effects are more pronounced at higher vibration amplitude. Both findings indicate that the presence of vibration promotes drowsiness, especially at higher vibration amplitude.

49 CFR Appendix C to Part 173 - Procedure for Base-level Vibration Testing

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 2 2012-10-01 2012-10-01 false Procedure for Base-level Vibration Testing C... Base-level Vibration Testing Base-level vibration testing shall be conducted as follows: 1. Three... platform. 4. Immediately following the period of vibration, each package shall be removed from the platform...

Observation of b 2 symmetry vibrational levels of the SO 2C 1B 2 state: Vibrational level staggering, Coriolis interactions, and rotation-vibration constants

DOE PAGES

Park, G. Barratt; Jiang, Jun; Saladrigas, Catherine A.; ...

2016-04-14

Here, the C 1B 2 state of SO 2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b 2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X ~ state are vibronically forbidden. We use IR-UV double resonance to observe the b 2 vibrational levels of the C state below 1600 cm –1 of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results frommore » the double-minimum potential. In addition, it allows us to deperturb the strong c-axis Coriolis interactions between levels of a 1 and b 2 vibrational symmetry, and to determine accurately the vibrational dependence of the rotational constants in the distorted C electronic state.« less

Observation of b 2 symmetry vibrational levels of the SO 2C 1B 2 state: Vibrational level staggering, Coriolis interactions, and rotation-vibration constants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, G. Barratt; Jiang, Jun; Saladrigas, Catherine A.

Here, the C 1B 2 state of SO 2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b 2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X ~ state are vibronically forbidden. We use IR-UV double resonance to observe the b 2 vibrational levels of the C state below 1600 cm –1 of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results frommore » the double-minimum potential. In addition, it allows us to deperturb the strong c-axis Coriolis interactions between levels of a 1 and b 2 vibrational symmetry, and to determine accurately the vibrational dependence of the rotational constants in the distorted C electronic state.« less

A noise control package for vibrating screens1),2)

PubMed Central

Lowe, M. Jenae; Yantek, David S.; Yang, Junyi; Schuster, Kevin C.; Mechling, Jessie J.

2015-01-01

Hearing loss was the second-most common illness reported to the Mine Safety and Health Administration (MSHA) in 2009. Furthermore, between 2000 and 2010, 30% of all noise-related injury complaints reported to MSHA were for coal preparation plant employees. Previous National Institute for Occupational Safety and Health (NIOSH) studies have shown that vibrating screens are key noise sources to address in order to reduce coal preparation plant noise. In response, NIOSH researchers have developed a suite of noise controls for vibrating screens consisting of constrained layer damping (CLD) treatments, a tuned mechanism suspension, an acoustic enclosure, and spring inserts. Laboratory testing demonstrates that this noise control suite reduces the A-weighted sound power level of the vibrating screen by 6 dB. To provide a comparison to laboratory results and prove durability, field testing of two noise controls was performed on a vibrating screen in a working coal preparation plant. The spring inserts and CLD treatments were selected due to their ease of installation and practicability. Field testing of these controls yielded reductions that were comparable to laboratory results. PMID:26257468

The translational, rotational, and vibrational energy effects on the chemical reactivity of water cation H2O+(X 2B1) in the collision with deuterium molecule D2

NASA Astrophysics Data System (ADS)

Xu, Yuntao; Xiong, Bo; Chang, Yih Chung; Ng, C. Y.

2013-07-01

By employing the newly established vacuum ultraviolet (VUV) laser pulsed field ionization-photoion (PFI-PI) double quadrupole-double octopole ion guide apparatus, we have examined the translational, rotational, and vibrational energy effects on the chemical reactivity of water cation H2O+(X2B1) in the collision with deuterium molecule D2. The application of a novel electric-field pulsing scheme to the VUV laser PFI-PI ion source has enabled the preparation of a rovibrationally selected H2O+(X2B1; v_1^ + v_2^ + v_3^ +; N+Ka+Kc+) ion beam with not only high internal-state selectivity and high intensity but also high translational energy resolution. Despite the unfavorable Franck-Condon factors, we are able to prepare the excited vibrational states (v_1^ + v_2^ + v_3^ +) = (100) and (020) along with the (000) ground vibrational state, for collisional studies, where v_1^ +, v_2^ +, and v_3^ + represent the symmetric stretching, bending, and asymmetric stretching modes of H2O+(X2B1). We show that a range of rotational levels from N+Ka+Kc+ = 000 to 322, covering a rotational energy range of 0-200 cm-1 of these vibrational states, can also be generated for absolute integral cross section (σ) measurements at center-of-mass collision energies (Ecms) from thermal energies to 10.00 eV. The Ecm dependences of the σ values are consistent with the prediction of the orbiting model, indicating that translational energy significantly hinders the chemical reactivity of H2O+(X2B1). Rotational enhancements are observed at Ecm < 0.30 eV for all the three vibrational states, (000), (100), and (020). While the σ values for (100) are found to be only slightly below those for (000), the σ values for (020) are lower than those for (000) and (100) by up to 20% at Ecm ≤ 0.20 eV, indicative of vibrational inhibition at low Ecm by excitation of the (020) mode. Rationalizations are proposed for the observed rotational enhancements and the bending vibrational inhibition. Rigorous theoretical calculations are needed to interpret the wealth of rovibrationally selected cross sections obtained in the present study.

On-off nonlinear active control of floor vibrations

NASA Astrophysics Data System (ADS)

Díaz, Iván M.; Reynolds, Paul

2010-08-01

Human-induced floor vibrations can be mitigated by means of active control via an electromagnetic proof-mass actuator. Previous researchers have developed a system for floor vibration comprising linear velocity feedback control (LVFC) with a command limiter (saturation in the command signal to avoid actuator overloading). The performance of this control is highly dependent on the linear gain utilised, which has to be designed for a particular excitation and might not be optimum for other excitations. This work explores the use of on-off nonlinear velocity feedback control (NLVFC) as the natural evolution of LVFC when high gains and/or significant vibration level are present together with saturation in the control law. Firstly, the describing function tool is employed to analyse the stability properties of: (1) LVFC with saturation, (2) on-off NLVFC with a dead zone and (3) on-off NLVFC with a switching-off function. Particular emphasis is paid to the resulting limit cycle behaviour and the design of appropriate dead zone and switching-off levels to avoid it. Secondly, experimental trials using the three control laws are conducted on a laboratory test floor. The results corroborate the analytical stability predictions. The pros of on-off NLVFC are that no gain has to be chosen and maximum actuator energy is delivered to cancel the vibration. In contrast, the requirement to select a dead zone or switching-off function provides a drawback in its application.

The ν 1 and ν 3 band system of 15NH3

NASA Astrophysics Data System (ADS)

Fusina, Luciano; Nivellini, Giandomenico; Spezzano, Silvia

2011-09-01

The infrared spectrum of 15NH3 has been investigated by high-resolution Fourier transform infrared spectroscopy in the region of the stretching fundamentals. A large number of ro-vibration transitions in the 3050-3650 cm-1 spectral range has been recorded and assigned to the fundamentals ν 1 and ν 3, and to the 2ν 4 overtone bands. In total, 1606 transitions involving the (s) and (a) inversion-rotation-vibration levels have been identified and assigned. They include 256 perturbation-allowed transitions with selection rules ΔK = ±2, Δl = -1 in ν 3 and Δl = +2 in ? , and ΔK = ±3, Δl = 0 in ν 1 and ? . All assigned transitions were fitted simultaneously to a model Hamiltonian that includes all symmetry-allowed interactions between and within the excited state levels in order to obtain accurate sets of spectroscopic parameters for both inversion states. The standard deviation of the fit, 0.034 cm-1, is about 70 times larger than the estimated measurement precision. This result is similar to that reported for the same band system in 14NH3 by Kleiner et al. [J. Mol. Spectrosc. 193, 46 (1999)] and is a consequence of the neglect of vibration and ro-vibration interactions between the analysed states and vibrationally excited states with close energies.

The effects of vibration-reducing gloves on finger vibration

PubMed Central

Welcome, Daniel E.; Dong, Ren G.; Xu, Xueyan S.; Warren, Christopher; McDowell, Thomas W.

2015-01-01

Vibration-reducing (VR) gloves have been used to reduce the hand-transmitted vibration exposures from machines and powered hand tools but their effectiveness remains unclear, especially for finger protection. The objectives of this study are to determine whether VR gloves can attenuate the vibration transmitted to the fingers and to enhance the understanding of the mechanisms of how these gloves work. Seven adult male subjects participated in the experiment. The fixed factors evaluated include hand force (four levels), glove condition (gel-filled, air bladder, no gloves), and location of the finger vibration measurement. A 3-D laser vibrometer was used to measure the vibrations on the fingers with and without wearing a glove on a 3-D hand-arm vibration test system. This study finds that the effect of VR gloves on the finger vibration depends on not only the gloves but also their influence on the distribution of the finger contact stiffness and the grip effort. As a result, the gloves increase the vibration in the fingertip area but marginally reduce the vibration in the proximal area at some frequencies below 100 Hz. On average, the gloves reduce the vibration of the entire fingers by less than 3% at frequencies below 80 Hz but increase at frequencies from 80 to 400 Hz. At higher frequencies, the gel-filled glove is more effective at reducing the finger vibration than the air bladder-filled glove. The implications of these findings are discussed. Relevance to industry Prolonged, intensive exposure to hand-transmitted vibration can cause hand-arm vibration syndrome. Vibration-reducing gloves have been used as an alternative approach to reduce the vibration exposure. However, their effectiveness for reducing finger-transmitted vibrations remains unclear. This study enhanced the understanding of the glove effects on finger vibration and provided useful information on the effectiveness of typical VR gloves at reducing the vibration transmitted to the fingers. The new results and knowledge can be used to help select appropriate gloves for the operations of powered hand tools, to help perform risk assessment of the vibration exposure, and to help design better VR gloves. PMID:26543297

Selected topics on the active control of helicopter aeromechanical and vibration problems

NASA Technical Reports Server (NTRS)

Friedmann, Peretz P.

1994-01-01

This paper describes in a concise manner three selected topics on the active control of helicopter aeromechanical and vibration problems. The three topics are as follows: (1) the active control of helicopter air-resonance using an LQG/LTR approach; (2) simulation of higher harmonic control (HHC) applied to a four bladed hingeless helicopter rotor in forward flight; and (3) vibration suppression in forward flight on a hingeless helicopter rotor using an actively controlled, partial span, trailing edge flap, which is mounted on the blade. Only a few selected illustrative results are presented. The results obtained clearly indicate that the partial span, actively controlled flap has considerable potential for vibration reduction in helicopter rotors.

Spectroscopic study on deuterated benzenes. III. Vibronic structure and dynamics in the S1 state

NASA Astrophysics Data System (ADS)

Kunishige, Sachi; Katori, Toshiharu; Kawabata, Megumi; Yamanaka, Takaya; Baba, Masaaki

2015-12-01

We observed the fluorescence excitation spectra and mass-selected resonance enhanced multiphoton ionization (REMPI) excitation spectra for the 6 01 , 6 01 10 1 , and 6 01 10 2 bands of the S1←S0 transition of jet-cooled deuterated benzene and assigned the vibronic bands of C6D6 and C6HD5. The 60 1 10 n (n = 0, 1, 2) and 00 0 transition energies were found to be dependent only on the number of D atoms (ND), which was reflected by the zero-point energy of each H/D isotopomer. In some isotopomers some bands, such as those of out-of-plane vibrations mixed with 611n, make the spectra complex. These included the 611021n level or combination bands with ν12 which are allowed because of reduced molecular symmetry. From the lifetime measurements of each vibronic band, some enhancement of the nonradiative intramolecular vibrational redistribution (IVR) process was observed. It was also found that the threshold excess energy of "channel three" was higher than the 6112 levels, which were similar for all the H/D isotopomers. We suggest that the channel three nonradiative process could be caused mainly by in-plane processes such as IVR and internal conversion at the high vibrational levels in the S1 state of benzene, although the out-of-plane vibrations might contribute to some degree.

49 CFR 178.819 - Vibration test.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Vibration test. 178.819 Section 178.819... Testing of IBCs § 178.819 Vibration test. (a) General. The vibration test must be conducted for the... vibration test. (b) Test method. (1) A sample IBC, selected at random, must be filled and closed as for...

Evaluation of haptic interfaces for simulation of drill vibration in virtual temporal bone surgery.

PubMed

Ghasemloonia, Ahmad; Baxandall, Shalese; Zareinia, Kourosh; Lui, Justin T; Dort, Joseph C; Sutherland, Garnette R; Chan, Sonny

2016-11-01

Surgical training is evolving from an observership model towards a new paradigm that includes virtual-reality (VR) simulation. In otolaryngology, temporal bone dissection has become intimately linked with VR simulation as the complexity of anatomy demands a high level of surgeon aptitude and confidence. While an adequate 3D visualization of the surgical site is available in current simulators, the force feedback rendered during haptic interaction does not convey vibrations. This lack of vibration rendering limits the simulation fidelity of a surgical drill such as that used in temporal bone dissection. In order to develop an immersive simulation platform capable of haptic force and vibration feedback, the efficacy of hand controllers for rendering vibration in different drilling circumstances needs to be investigated. In this study, the vibration rendering ability of four different haptic hand controllers were analyzed and compared to find the best commercial haptic hand controller. A test-rig was developed to record vibrations encountered during temporal bone dissection and a software was written to render the recorded signals without adding hardware to the system. An accelerometer mounted on the end-effector of each device recorded the rendered vibration signals. The newly recorded vibration signal was compared with the input signal in both time and frequency domains by coherence and cross correlation analyses to quantitatively measure the fidelity of these devices in terms of rendering vibrotactile drilling feedback in different drilling conditions. This method can be used to assess the vibration rendering ability in VR simulation systems and selection of ideal haptic devices. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nuclear spin/parity dependent spectroscopy and predissociation dynamics in vOH = 2 ← 0 overtone excited Ne-H2O clusters: Theory and experiment

NASA Astrophysics Data System (ADS)

Ziemkiewicz, Michael P.; Pluetzer, Christian; Loreau, Jérôme; van der Avoird, Ad; Nesbitt, David J.

2017-12-01

Vibrationally state selective overtone spectroscopy and state- and nuclear spin-dependent predissociation dynamics of weakly bound ortho- and para-Ne-H2O complexes (D0(ortho) = 34.66 cm-1 and D0(para) = 31.67 cm-1) are reported, based on near-infrared excitation of van der Waals cluster bands correlating with vOH = 2 ← 0 overtone transitions (|02-〉 and |02+〉) out of the ortho (101) and para (000) internal rotor states of the H2O moiety. Quantum theoretical calculations for nuclear motion on a high level potential energy surface [CCSD(T)/VnZf12 (n = 3, 4)], corrected for basis set superposition error and extrapolated to the complete basis set (CBS) limit, are employed to successfully predict and assign Π-Σ, Σ-Σ, and Σ-Π infrared bands in the spectra, where Σ or Π represent approximate projections of the body-fixed H2O angular momentum along the Ne-H2O internuclear axis. IR-UV pump-probe experimental capabilities permit real-time measurements of the vibrational predissociation dynamics, which indicate facile intramolecular vibrational energy transfer from the H2O vOH = 2 overtone vibrations into the VdWs (van der Waals) dissociation coordinate on the τprediss = 15-25 ns time scale. Whereas all predicted strong transitions in the ortho-Ne-H2O complexes are readily detected and assigned, vibrationally mediated photolysis spectra for the corresponding para-Ne-H2O bands are surprisingly absent despite ab initio predictions of Q-branch intensities with S/N > 20-40. Such behavior signals the presence of highly selective nuclear spin ortho-para predissociation dynamics in the upper state, for which we offer a simple mechanism based on Ne-atom mediated intramolecular vibrational relaxation in the H2O subunit (i.e., |02±〉 → {|01±〉; v2 = 2}), which is confirmed by the ab initio energy level predictions and the nascent OH rotational (N), spin orbit (Π1/2,3/2), and lambda doublet product distributions.

Driving an Active Vibration Balancer to Minimize Vibrations at the Fundamental and Harmonic Frequencies

NASA Technical Reports Server (NTRS)

Holliday, Ezekiel S. (Inventor)

2014-01-01

Vibrations of a principal machine are reduced at the fundamental and harmonic frequencies by driving the drive motor of an active balancer with balancing signals at the fundamental and selected harmonics. Vibrations are sensed to provide a signal representing the mechanical vibrations. A balancing signal generator for the fundamental and for each selected harmonic processes the sensed vibration signal with adaptive filter algorithms of adaptive filters for each frequency to generate a balancing signal for each frequency. Reference inputs for each frequency are applied to the adaptive filter algorithms of each balancing signal generator at the frequency assigned to the generator. The harmonic balancing signals for all of the frequencies are summed and applied to drive the drive motor. The harmonic balancing signals drive the drive motor with a drive voltage component in opposition to the vibration at each frequency.

49 CFR Appendix C to Part 173 - Procedure for Base-level Vibration Testing

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 2 2013-10-01 2013-10-01 false Procedure for Base-level Vibration Testing C Appendix C to Part 173 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS... Base-level Vibration Testing Base-level vibration testing shall be conducted as follows: 1. Three...

49 CFR Appendix C to Part 173 - Procedure for Base-level Vibration Testing

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Procedure for Base-level Vibration Testing C Appendix C to Part 173 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS... Base-level Vibration Testing Base-level vibration testing shall be conducted as follows: 1. Three...

Collisional Removal of O2 (c(sup 1) Sigma(sup-)(sub u), nu=9) by O2, N2, and He

NASA Technical Reports Server (NTRS)

Copeland, Richard A.; Knutsen, Karen; Onishi, Marc E.; Yalcin, Talat

1996-01-01

The collisional removal Of 02 molecules in selected vibrational levels of the c state is studied using a two-laser double-resonance technique. The output of the first laser excites the 02 to nu = 9 or 10 of the c Sigma - state, and the ultraviolet output of the second laser monitors specific rovibrational levels via resonance-enhanced ionization. The temporal evolution of the c Sigma u state vibrational level is observed by scanning the time delay between the two pulsed lasers. As the rate constants for 02 and N2 are similar in magnitude, N2 collisions dominate the removal rate in the earth's atmosphere. For v= 10 colliding with 02, we find a removal rate constant that is 2-5 times that for v=9 and that single quantum collision cascade is an important pathway for removal.

Probing cis-trans isomerization in the S{sub 1} state of C{sub 2}H{sub 2} via H-atom action and hot band-pumped IR-UV double resonance spectroscopies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Changala, P. Bryan; Baraban, Joshua H.; Field, Robert W., E-mail: rwfield@mit.edu

2015-08-28

We report novel experimental strategies that should prove instrumental in extending the vibrational and rotational assignments of the S{sub 1} state of acetylene, C{sub 2}H{sub 2}, in the region of the cis-trans isomerization barrier. At present, the assignments are essentially complete up to ∼500 cm{sup −1} below the barrier. Two difficulties arise when the assignments are continued to higher energies. One is that predissociation into C{sub 2}H + H sets in roughly 1100 cm{sup −1} below the barrier; the resulting quenching of laser-induced fluorescence (LIF) reduces its value for recording spectra in this region. The other difficulty is that tunnelingmore » through the barrier causes a staggering in the K-rotational structure of isomerizing vibrational levels. The assignment of these levels requires data for K values up to at least 3. Given the rotational selection rule K′ − ℓ{sup ′′} = ± 1, such data must be obtained via excited vibrational levels of the ground state with ℓ{sup ′′} > 0. In this paper, high resolution H-atom resonance-enhanced multiphoton ionization spectra are demonstrated to contain predissociated bands which are almost invisible in LIF spectra, while preliminary data using a hyperthermal pulsed nozzle show that ℓ{sup ′′} = 2 states can be selectively populated in a jet, giving access to K′ = 3 states in IR-UV double resonance.« less

Amplified Pilot Head Vibration and the Effects of Vibration Mitigation on Neck Muscle Strain.

PubMed

Wright Beatty, Heather E; Law, Andrew J; Thomas, J Russell; Wickramasinghe, Viresh

2018-06-01

Rotary wing pilot neck strain is increasing in prevalence due to the combined effects of head supported mass (e.g., Night Vision Goggles, head mounted displays) and whole-body vibration. This study examined the physiological responses of pilots during exposure to whole-body vibration (WBV) representative of the National Research Council's Bell 412 helicopter in forward flight. WBV levels were measured and evaluated using the ISO-2631-1-1997 WBV standards. Twelve pilots (aged 20-59 yr, 7 of the 12 with 20+ years flight experience) underwent six 15-min vibration trials on a human rated shaker platform. Participants were exposed to three vibration levels (-25%, normal, and +25% amplitude; Levels 1-3, respectively) while seated on an Original Equipment Manufacturer (OEM) or vibration mitigating (MIT) cushion. Upper back and neck electromyography (EMG) and acceleration were continuously recorded. Normalized EMG amplitude was higher using the OEM compared to the MIT during Level 2 (0.18 vs. -0.27) and Level 3 (0.24 vs. -0.14) for the anterior neck muscles. Health weighted vibration amplitude at the head (Mean of 3 levels: OEM = 1.19 and MIT = 1.11 m · s-2) was larger than the vibration amplitude at the seat (Mean of 3 levels: OEM = 0.77 and MIT = 0.70 m · s-2). The amplification of head vibration relative to the seat, and the significant effects of vibration level, as well as the vibration mitigation cushion, on neck EMG amplitude support the need for revisions to the ISO-2631-1 standard to account for the head and neck response to whole-body vibration.Wright Beatty HE, Law AJ, Thomas JR, Wickramasinghe V. Amplified pilot head vibration and the effects of vibration mitigation on neck muscle strain. Aerosp Med Hum Perform. 2018; 89(6):510-519.

Balancing Vibrations at Harmonic Frequencies by Injecting Harmonic Balancing Signals into the Armature of a Linear Motor/Alternator Coupled to a Stirling Machine

NASA Technical Reports Server (NTRS)

Holliday, Ezekiel S. (Inventor)

2014-01-01

Vibrations at harmonic frequencies are reduced by injecting harmonic balancing signals into the armature of a linear motor/alternator coupled to a Stirling machine. The vibrations are sensed to provide a signal representing the mechanical vibrations. A harmonic balancing signal is generated for selected harmonics of the operating frequency by processing the sensed vibration signal with adaptive filter algorithms of adaptive filters for each harmonic. Reference inputs for each harmonic are applied to the adaptive filter algorithms at the frequency of the selected harmonic. The harmonic balancing signals for all of the harmonics are summed with a principal control signal. The harmonic balancing signals modify the principal electrical drive voltage and drive the motor/alternator with a drive voltage component in opposition to the vibration at each harmonic.

Effects of whole-body vibration on plasma sclerostin level in healthy women.

PubMed

Çidem, Muharrem; Karakoç, Yunus; Ekmekçi, Hakan; Küçük, Suat Hayri; Uludağ, Murat; Gün, Kerem; Karamehmetoğlu, Safak Sahir; Karacan, İlhan

2014-01-01

To determine whether plasma sclerostin levels are affected by applying whole-body vibration treatments. Following a pilot study, the pretsent prospective, randomized, controlled single-blind study was performed on 16 healthy volunteer women (ages 20 to 40 years). Subjects were randomly divided into 2 groups, and whole-body vibration was applied to the treatment group but not to the controls. The plasma sclerostin levels were measured before the treatment and at the 10th minute after whole-body vibration on the 1st, 2nd, and 5th days of application. The plasma sclerostin level measured at 10 min after the whole-body vibration treatment increased 91% (P = 0.024) on the 1st day and decreased 31.5% (P = 0.03) on the 5th day in the whole-body vibration group. In the control group, there was no change in the plasma sclerostin level at any time. A progressive increase in baseline plasma sclerostin levels during the 5 days of vibration sessions was also found. Our study demonstrated that whole-body vibration can change plasma sclerostin levels, and that this change is detectable 10 min after whole-body vibration treatments.

Concorde noise-induced building vibrations John F. Kennedy International Airport

NASA Technical Reports Server (NTRS)

Mayes, W. H.; Deloach, R.; Stephens, D. G.; Cawthorn, J. M.; Holmes, H. K.; Lewis, R. B.; Holliday, B. G.; Ward, D. W.

1978-01-01

The outdoor and indoor noise levels resulting from aircraft flyovers and certain nonaircraft events were recorded at six home sites along with the associated vibration levels in the walls, windows, and floors of these test homes. Limited subjective tests conducted to examine the human detection and annoyance thresholds for building vibration and rattle caused by aircraft noise showed that both vibration and rattle were detected subjectively in several houses for some operations of both the Concorde and subsonic aircraft. Preliminary results indicate that the relationship between window vibration and aircraft noise is: (1) linear, with vibration levels being accurately predicted from OASPL levels measured near the window; (2) consistent from flyover to flyover for a given aircraft type under approach conditions; (3) no different for Concorde than for other conventional jet transports (in the case of window vibrations induced under approach power conditions); and (4) relatively high levels of window vibration measured during Concorde operations are due more to higher OASPL levels than to unique Concorde source characteristics.

Analyses of the most influential factors for vibration monitoring of planetary power transmissions in pellet mills by adaptive neuro-fuzzy technique

NASA Astrophysics Data System (ADS)

Milovančević, Miloš; Nikolić, Vlastimir; Anđelković, Boban

2017-01-01

Vibration-based structural health monitoring is widely recognized as an attractive strategy for early damage detection in civil structures. Vibration monitoring and prediction is important for any system since it can save many unpredictable behaviors of the system. If the vibration monitoring is properly managed, that can ensure economic and safe operations. Potentials for further improvement of vibration monitoring lie in the improvement of current control strategies. One of the options is the introduction of model predictive control. Multistep ahead predictive models of vibration are a starting point for creating a successful model predictive strategy. For the purpose of this article, predictive models of are created for vibration monitoring of planetary power transmissions in pellet mills. The models were developed using the novel method based on ANFIS (adaptive neuro fuzzy inference system). The aim of this study is to investigate the potential of ANFIS for selecting the most relevant variables for predictive models of vibration monitoring of pellet mills power transmission. The vibration data are collected by PIC (Programmable Interface Controller) microcontrollers. The goal of the predictive vibration monitoring of planetary power transmissions in pellet mills is to indicate deterioration in the vibration of the power transmissions before the actual failure occurs. The ANFIS process for variable selection was implemented in order to detect the predominant variables affecting the prediction of vibration monitoring. It was also used to select the minimal input subset of variables from the initial set of input variables - current and lagged variables (up to 11 steps) of vibration. The obtained results could be used for simplification of predictive methods so as to avoid multiple input variables. It was preferable to used models with less inputs because of overfitting between training and testing data. While the obtained results are promising, further work is required in order to get results that could be directly applied in practice.

Application of the wavelet packet transform to vibration signals for surface roughness monitoring in CNC turning operations

NASA Astrophysics Data System (ADS)

García Plaza, E.; Núñez López, P. J.

2018-01-01

The wavelet packet transform method decomposes a time signal into several independent time-frequency signals called packets. This enables the temporary location of transient events occurring during the monitoring of the cutting processes, which is advantageous in monitoring condition and fault diagnosis. This paper proposes the monitoring of surface roughness using a single low cost sensor that is easily implemented in numerical control machine tools in order to make on-line decisions on workpiece surface finish quality. Packet feature extraction in vibration signals was applied to correlate the sensor signals to measured surface roughness. For the successful application of the WPT method, mother wavelets, packet decomposition level, and appropriate packet selection methods should be considered, but are poorly understood aspects in the literature. In this novel contribution, forty mother wavelets, optimal decomposition level, and packet reduction methods were analysed, as well as identifying the effective frequency range providing the best packet feature extraction for monitoring surface finish. The results show that mother wavelet biorthogonal 4.4 in decomposition level L3 with the fusion of the orthogonal vibration components (ax + ay + az) were the best option in the vibration signal and surface roughness correlation. The best packets were found in the medium-high frequency DDA (6250-9375 Hz) and high frequency ADA (9375-12500 Hz) ranges, and the feed acceleration component ay was the primary source of information. The packet reduction methods forfeited packets with relevant features to the signal, leading to poor results for the prediction of surface roughness. WPT is a robust vibration signal processing method for the monitoring of surface roughness using a single sensor without other information sources, satisfactory results were obtained in comparison to other processing methods with a low computational cost.

Pump and probe spectroscopy with continuous wave quantum cascade lasers.

PubMed

Kirkbride, James M R; Causier, Sarah K; Dalton, Andrew R; Weidmann, Damien; Ritchie, Grant A D

2014-02-07

This paper details infra-red pump and probe studies on nitric oxide conducted with two continuous wave quantum cascade lasers both operating around 5 μm. The pump laser prepares a velocity selected population in a chosen rotational quantum state of the v = 1 level which is subsequently probed using a second laser tuned to a rotational transition within the v = 2 ← v = 1 hot band. The rapid frequency scan of the probe (with respect to the molecular collision rate) in combination with the velocity selective pumping allows observation of marked rapid passage signatures in the transient absorption profiles from the polarized vibrationally excited sample. These coherent transient signals are influenced by the underlying hyperfine structure of the pump and probe transitions, the sample pressure, and the coherent properties of the lasers. Pulsed pump and probe studies show that the transient absorption signals decay within 1 μs at 50 mTorr total pressure, reflecting both the polarization and population dephasing times of the vibrationally excited sample. The experimental observations are supported by simulation based upon solving the optical Bloch equations for a two level system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirkbride, James M. R.; Causier, Sarah K.; Dalton, Andrew R.

This paper details infra-red pump and probe studies on nitric oxide conducted with two continuous wave quantum cascade lasers both operating around 5 μm. The pump laser prepares a velocity selected population in a chosen rotational quantum state of the v = 1 level which is subsequently probed using a second laser tuned to a rotational transition within the v = 2 ← v = 1 hot band. The rapid frequency scan of the probe (with respect to the molecular collision rate) in combination with the velocity selective pumping allows observation of marked rapid passage signatures in the transient absorptionmore » profiles from the polarized vibrationally excited sample. These coherent transient signals are influenced by the underlying hyperfine structure of the pump and probe transitions, the sample pressure, and the coherent properties of the lasers. Pulsed pump and probe studies show that the transient absorption signals decay within 1 μs at 50 mTorr total pressure, reflecting both the polarization and population dephasing times of the vibrationally excited sample. The experimental observations are supported by simulation based upon solving the optical Bloch equations for a two level system.« less

Electronic damping of anharmonic adsorbate vibrations at metallic surfaces

NASA Astrophysics Data System (ADS)

Tremblay, Jean Christophe; Monturet, Serge; Saalfrank, Peter

2010-03-01

The nonadiabatic coupling of an adsorbate close to a metallic surface leads to electronic damping of adsorbate vibrations and line broadening in vibrational spectroscopy. Here, a perturbative treatment of the electronic contribution to the lifetime broadening serves as a building block for a new approach, in which anharmonic vibrational transition rates are calculated from a position-dependent coupling function. Different models for the coupling function will be tested, all related to embedding theory. The first two are models based on a scattering approach with (i) a jellium-type and (ii) a density functional theory based embedding density, respectively. In a third variant a further refined model is used for the embedding density, and a semiempirical approach is taken in which a scaling factor is chosen to match harmonic, single-site, first-principles transition rates, obtained from periodic density functional theory. For the example of hydrogen atoms on (adsorption) and below (subsurface absorption) a Pd(111) surface, lifetimes of and transition rates between vibrational levels are computed. The transition rates emerging from different models serve as input for the selective subsurface adsorption of hydrogen in palladium starting from an adsorption site, by using sequences of infrared laser pulses in a laser distillation scheme.

In vivo imaging and vibration measurement of Guinea pig cochlea

NASA Astrophysics Data System (ADS)

Choudhury, Niloy; Chen, Fangyi; Zheng, Jiefu; Nuttall, Alfred L.; Jacques, Steven L.

2008-02-01

An optical coherence tomography (OCT) system was built to acquire in vivo, both images and vibration measurements of the organ of Corti of the guinea pig. The organ of Corti was viewed through a ~500-μm diameter hole in the bony wall of the scala tympani of the first cochlear turn. In imaging mode, the image was acquired as reflectance R(x,z). In vibration mode, the basilar membrane (BM) or reticular lamina (RL) was selected based on the image. Under software control, the system would move the scanning mirrors to bring the sensing volume of the measurement to the desired tissue location. To address the gain stability problem of the homodyne OCT system, arising from the system moving in and out of the quadrature point and also to resolve the 180 degree ambiguity in the phase measurement using an interferometer, a vibration calibration method is developed by adding a vibrating source to the reference arm to monitor the operating point of the interferometric system. Amplitude gain and phase of various cochlear membranes was measured for different sound pressure level (SPL) varying from 65dB SPL to 93 dB SPL.

Actuator placement in prestressed adaptive trusses for vibration control

NASA Technical Reports Server (NTRS)

Jalihal, P.; Utku, Senol; Wada, Ben K.

1993-01-01

This paper describes the optimal location selection of actuators for vibration control in prestressed adaptive trusses. Since prestressed adaptive trusses are statically indeterminate, the actuators to be used for vibration control purposes must work against (1) existing static axial prestressing forces, (2) static axial forces caused by the actuation, and (3) dynamic axial forces caused by the motion of the mass. In statically determinate adaptive trusses (1) and (2) are non - existing. The actuator placement problem in statically indeterminate trusses is therefore governed by the actuation energy and the actuator strength requirements. Assuming output feedback type control of selected vibration modes in autonomous systems, a procedure is given for the placement of vibration controlling actuators in prestressed adaptive trusses.

Collisional quenching at ultralow energies: controlling efficiency with internal state selection.

PubMed

Bovino, S; Bodo, E; Gianturco, F A

2007-12-14

Calculations have been carried out for the vibrational quenching of excited H(2) molecules which collide with Li(+) ions at ultralow energies. The dynamics has been treated exactly using the well-known quantum coupled-channel expansions over different initial vibrational levels. The overall interaction potential has been obtained from the calculations carried out earlier by our group using highly correlated ab initio methods. The results indicate that specific features of the scattering observables, e.g., the appearance of Ramsauer-Townsend minima in elastic channel cross sections and the marked increase of the cooling rates from specific initial states, can be linked to potential properties at vanishing energies (sign and size of scattering lengths) and to the presence of either virtual states or bound states. The suggestion is made such that by selecting the initial state preparation of the molecular partners, the ionic interactions would be amenable to controlling quenching efficiency at ultralow energies.

Mode-selective vibrational modulation of charge transport in organic electronic devices

PubMed Central

Bakulin, Artem A.; Lovrincic, Robert; Yu, Xi; Selig, Oleg; Bakker, Huib J.; Rezus, Yves L. A.; Nayak, Pabitra K.; Fonari, Alexandr; Coropceanu, Veaceslav; Brédas, Jean-Luc; Cahen, David

2015-01-01

The soft character of organic materials leads to strong coupling between molecular, nuclear and electronic dynamics. This coupling opens the way to influence charge transport in organic electronic devices by exciting molecular vibrational motions. However, despite encouraging theoretical predictions, experimental realization of such approach has remained elusive. Here we demonstrate experimentally that photoconductivity in a model organic optoelectronic device can be modulated by the selective excitation of molecular vibrations. Using an ultrafast infrared laser source to create a coherent superposition of vibrational motions in a pentacene/C60 photoresistor, we observe that excitation of certain modes in the 1,500–1,700 cm−1 region leads to photocurrent enhancement. Excited vibrations affect predominantly trapped carriers. The effect depends on the nature of the vibration and its mode-specific character can be well described by the vibrational modulation of intermolecular electronic couplings. This presents a new tool for studying electron–phonon coupling and charge dynamics in (bio)molecular materials. PMID:26246039

Mode-selective vibrational modulation of charge transport in organic electronic devices

NASA Astrophysics Data System (ADS)

Bakulin, Artem A.; Lovrincic, Robert; Yu, Xi; Selig, Oleg; Bakker, Huib J.; Rezus, Yves L. A.; Nayak, Pabitra K.; Fonari, Alexandr; Coropceanu, Veaceslav; Brédas, Jean-Luc; Cahen, David

2015-08-01

The soft character of organic materials leads to strong coupling between molecular, nuclear and electronic dynamics. This coupling opens the way to influence charge transport in organic electronic devices by exciting molecular vibrational motions. However, despite encouraging theoretical predictions, experimental realization of such approach has remained elusive. Here we demonstrate experimentally that photoconductivity in a model organic optoelectronic device can be modulated by the selective excitation of molecular vibrations. Using an ultrafast infrared laser source to create a coherent superposition of vibrational motions in a pentacene/C60 photoresistor, we observe that excitation of certain modes in the 1,500-1,700 cm-1 region leads to photocurrent enhancement. Excited vibrations affect predominantly trapped carriers. The effect depends on the nature of the vibration and its mode-specific character can be well described by the vibrational modulation of intermolecular electronic couplings. This presents a new tool for studying electron-phonon coupling and charge dynamics in (bio)molecular materials.

Whole-body vibration exposure: a comprehensive field study.

PubMed

Ozkaya, N; Willems, B; Goldsheyder, D

1994-12-01

A comprehensive field study investigated whole-body vibration exposure levels experienced by the train operators of a large metropolitan subway system. The purposes of the study were to measure mechanical vibrations transmitted to the seated train operators, to calculate daily whole-body vibration exposure levels, and to compare these levels with maximum acceptable exposure levels recommended by the international standard on whole-body vibration (ISO 2631). The study also sought to identify factors that may influence mechanical vibrations transmitted to the operators and quantify their effects on the measured vibration levels. The study was carried out by dividing the subway system into subway lines, each line into southbound and northbound directions, and each direction into station-to-station observations. Triaxial measurements were made on all subway lines and for all car types used in the system. For each line, at least two round trips of data were collected. Time-weighted averages of the two sets of data were used for final presentation. A total of 48 round trips were made and more than 100 hours of vibration data was collected and analyzed. All phases of the study were carried out in accordance with the procedures outlined in ISO 2631. It was determined that 6 out of 20 subway lines had vibration levels higher than daily exposure limits recommended by ISO 2631. It was also determined that train speed was the most significant factor influencing vibration exposure levels.

Rotational spectrum of NSF3 in the ground and v5 = 1 vibrational states: observation of Q-branch perturbation-allowed transitions with delta(k - l) = 0, +/-3, +/-6 and anomalies in the rovibrational structure of the v5 = 1 state.

PubMed

Macholl, Sven; Mäder, Heinrich; Harder, Hauke; Margulès, Laurent; Dréan, Pascal; Cosléou, Jean; Demaison, Jean; Pracna, Petr

2009-01-29

The rotational spectrum of NSF3 in the ground and v5 = 1 vibrational states has been investigated in the centimeter- and millimeter-wave ranges. R-branch (J + 1 <-- J) transitions for J = 0, 1 and Q-branch rotational transitions for the v5 = 1 vibrational state have been measured by waveguide Fourier transform microwave spectroscopy in the range 8-26.5 GHz. The Q-branch transitions include 28 direct l-type doubling transitions (kl = +1, A1) <--> (kl = +1, A2) with J < or = 62, and 108 direct l-type resonance transitions following the selection rule delta k = delta l = +/-2 with J < or = 60 and G = |k - l| < or = 3. A process called "regional resonance" was observed in which a cluster of levels interacted strongly over a large range in J. This process led to the observation of 55 perturbation-allowed transitions following the selection rules delta(k - l) = +/-3, +/-6. In particular, (kl = +1, A+) <--> (kl = -2, A-), (kl = +4, A+) <--> (kl = +1, A-), (kl = +2) <--> (kl = -1), (kl = +3) <--> (kl = 0), (kl = +2) <--> (kl = -3), and (kl = +3) <--> (kl = -3). The various aspects of the regional resonances are discussed in detail. An accidental near-degeneracy of the kl = 0 and kl = -4 levels at J = 26/27 led to the observation of perturbation-allowed transitions following the selection rule delta(k-l) = +/-6 with (kl = +2) <--> (kl = -4). A corresponding near-degeneracy between kl = -1 and kl = -3 levels at J = 30/31 led to the detection of similar transitions, but with (kl = +3) <--> (kl = -3). In the range 230-480 GHz, R-branch rotational transitions have been measured by absorption spectroscopy up to J = 49 in the ground-state and up to J = 50 in the v5 = 1 vibrational state. The transition frequencies have been analyzed using various reduced forms of the effective Hamiltonians. The data for the v5 = 1 vibrational state have been fitted successfully using two models up to seventh order with delta k = +/-3 interaction parameters constrained (dt constrained to zero, and epsilon to zero or to the ground-state value). On the other hand, reductions with the (delta k = +/-1, deltal = -/+2) interaction parameter q12 fixed to zero failed to reproduce the experimental data since the parameters defining the reduction transformation do not arise in the correct order of magnitude. The ground-state data have been analyzed including parameters up to fourth order constraining either parameters of the delta k = +/-3 interactions to zero (reduction A), or of the delta k = +/-6 interactions to zero (reduction B). The unitary equivalence of the different parameter sets obtained is demonstrated for both vibrational states.

Influence of low-frequency vibration on changes of biochemical parameters of living rats

NASA Astrophysics Data System (ADS)

Kasprzak, Cezary; Damijan, Zbigniew; Panuszka, Ryszard

2004-05-01

The aim of the research was to investigate how some selected biochemical parameters of living rats depend on exposure of low-frequency vibrations. Experiments were run on 30 Wistar rats randomly segregated into three groups: (I) 20 days old (before puberty), (II) 70th day after; (III) control group. The exposure was repeated seven times, for 3 h, at the same time of day. Vibrations applied during the first tests of the experiment had acceleration 1.22 m/s2 and frequency 20 Hz. At the 135th day the rats' bones were a subject of morphometric/biochemical examination. The results of biochemical tests proved decrease in LDL and HDL cholesterol levels for exposed rats as well as the Ca contents in blood plasma. There was evident increasing of Ca in blood plasma in exposed rats for frequency of exposition.

The Dornier 328 Acoustic Test Cell (ATC) for interior noise tests and selected test results

NASA Technical Reports Server (NTRS)

Hackstein, H. Josef; Borchers, Ingo U.; Renger, Klaus; Vogt, Konrad

1992-01-01

To perform acoustic studies for achieving low noise levels for the Dornier 328, an acoustic test cell (ATC) of the Dornier 328 has been built. The ATC consists of a fuselage section, a realistic fuselage suspension system, and three exterior noise simulation rings. A complex digital 60 channel computer/amplifier noise generation system as well as multichannel digital data acquisition and evaluation system have been used. The noise control tests started with vibration measurements for supporting acoustic data interpretation. In addition, experiments have been carried out on dynamic vibration absorbers, the most important passive noise reduction measure for low frequency propeller noise. The design and arrangement of the current ATC are presented. Furthermore, exterior noise simulation as well as data acquisition are explained. The most promising results show noise reduction due to synchrophasing and dynamic vibration absorbers.

Pulsed-field ionization zero electron kinetic energy spectrum of the ground electronic state of BeOBe+.

PubMed

Antonov, Ivan O; Barker, Beau J; Heaven, Michael C

2011-01-28

The ground electronic state of BeOBe(+) was probed using the pulsed-field ionization zero electron kinetic energy photoelectron technique. Spectra were rotationally resolved and transitions to the zero-point level, the symmetric stretch fundamental and first two bending vibrational levels were observed. The rotational state symmetry selection rules confirm that the ground electronic state of the cation is (2)Σ(g)(+). Detachment of an electron from the HOMO of neutral BeOBe results in little change in the vibrational or rotational constants, indicating that this orbital is nonbonding in nature. The ionization energy of BeOBe [65480(4) cm(-1)] was refined over previous measurements. Results from recent theoretical calculations for BeOBe(+) (multireference configuration interaction) were found to be in good agreement with the experimental data.

Comparison of Annoyance from Railway Noise and Railway Vibration.

PubMed

Ögren, Mikael; Gidlöf-Gunnarsson, Anita; Smith, Michael; Gustavsson, Sara; Persson Waye, Kerstin

2017-07-19

The aim of this study is to compare vibration exposure to noise exposure from railway traffic in terms of equal annoyance, i.e., to determine when a certain noise level is equally annoying as a corresponding vibration velocity. Based on questionnaire data from the Train Vibration and Noise Effects (TVANE) research project from residential areas exposed to railway noise and vibration, the dose response relationship for annoyance was estimated. By comparing the relationships between exposure and annoyance for areas both with and without significant vibration exposure, the noise levels and vibration velocities that had an equal probability of causing annoyance was determined using logistic regression. The comparison gives a continuous mapping between vibration velocity in the ground and a corresponding noise level at the facade that are equally annoying. For equivalent noise level at the facade compared to maximum weighted vibration velocity in the ground the probability of annoyance is approximately 20% for 59 dB or 0.48 mm/s, and about 40% for 63 dB or 0.98 mm/s.

Implausibility of the vibrational theory of olfaction

DOE PAGES

Block, Eric; Ertem, Mehmed Z.; Jang, Seogjoo; ...

2015-04-21

The vibrational theory of olfaction assumes that electron transfer occurs across odorants at the active sites of odorant receptors (ORs), serving as a sensitive measure of odorant vibrational frequencies, ultimately leading to olfactory perception. A previous study reported that human subjects differentiated hydrogen/deuterium isotopomers (isomers with isotopic atoms) of the musk compound cyclopentadecanone as evidence supporting the theory. Here, we find no evidence for such differentiation at the molecular level. In fact, we find that the human musk-recognizing receptor, OR5AN1, identified using a heterologous OR expression system and robustly responding to cyclopentadecanone and muscone, fails to distinguish isotopomers of thesemore » compounds in vitro. Furthermore, the mouse (methylthio)methanethiol (MTMT)-recognizing receptor, MOR244-3, and other selected human and mouse ORs, responded similarly to normal, deuterated, and ¹³C isotopomers of their respective ligands, paralleling our results with the musk receptor OR5AN1. These findings suggest that the proposed vibration theory does not apply to the human musk receptor OR5AN1, mouse thiol receptor MOR244-3, or other ORs examined. Also, contrary to the vibration theory predictions, muscone-d₃₀ lacks the 1,380-1,550 cm⁻¹ IR bands claimed to be essential for musk odor. Furthermore, our theoretical analysis shows that the proposed electron transfer mechanism of the vibrational frequencies of odorants could be easily suppressed by quantum effects of non-odorant molecular vibrational modes. As a result, these and other concerns about electron transfer at ORs, together with our extensive experimental data, argue against the plausibility of the vibration theory.« less

Physiology responses of Rhesus monkeys to vibration

NASA Astrophysics Data System (ADS)

Hajebrahimi, Zahra; Ebrahimi, Mohammad; Alidoust, Leila; Arabian Hosseinabadi, Maedeh

Vibration is one of the important environmental factors in space vehicles that it can induce severe physiological responses in most of the body systems such as cardiovascular, respiratory, skeletal, endocrine, and etc. This investigation was to assess the effect of different vibration frequencies on heart rate variability (HRV), electrocardiograms (ECG) and respiratory rate in Rhesus monkeys. Methods: two groups of rhesus monkey (n=16 in each group) was selected as control and intervention groups. Monkeys were held in a sitting position within a specific fixture. The animals of this experiment were vibrated on a table which oscillated right and left with sinusoidal motion. Frequency and acceleration for intervention group were between the range of 1 to 2000 Hz and +0.5 to +3 G during 36 weeks (one per week for 15 min), respectively. All of the animals passed the clinical evaluation (echocardiography, sonography, radiography and blood analysis test) before vibration test and were considered healthy and these tests repeated during and at the end of experiments. Results and discussions: Our results showed that heart and respiratory rates increased significantly in response to increased frequency from 1 to 60 Hz (p <0.05) directly with the +G level reaching a maximum (3G) within a seconds compare to controls. There were no significant differences in heart and respiratory rate from 60 t0 2000 Hz among studied groups. All monkeys passed vibration experiment successfully without any arrhythmic symptoms due to electrocardiography analysis. Conclusion: Our results indicate that vibration in low frequency can effect respiratory and cardiovascular function in rhesus monkey. Keywords: Vibration, rhesus monkey, heart rate, respiratory rate

Implausibility of the vibrational theory of olfaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Block, Eric; Ertem, Mehmed Z.; Jang, Seogjoo

The vibrational theory of olfaction assumes that electron transfer occurs across odorants at the active sites of odorant receptors (ORs), serving as a sensitive measure of odorant vibrational frequencies, ultimately leading to olfactory perception. A previous study reported that human subjects differentiated hydrogen/deuterium isotopomers (isomers with isotopic atoms) of the musk compound cyclopentadecanone as evidence supporting the theory. Here, we find no evidence for such differentiation at the molecular level. In fact, we find that the human musk-recognizing receptor, OR5AN1, identified using a heterologous OR expression system and robustly responding to cyclopentadecanone and muscone, fails to distinguish isotopomers of thesemore » compounds in vitro. Furthermore, the mouse (methylthio)methanethiol (MTMT)-recognizing receptor, MOR244-3, and other selected human and mouse ORs, responded similarly to normal, deuterated, and ¹³C isotopomers of their respective ligands, paralleling our results with the musk receptor OR5AN1. These findings suggest that the proposed vibration theory does not apply to the human musk receptor OR5AN1, mouse thiol receptor MOR244-3, or other ORs examined. Also, contrary to the vibration theory predictions, muscone-d₃₀ lacks the 1,380-1,550 cm⁻¹ IR bands claimed to be essential for musk odor. Furthermore, our theoretical analysis shows that the proposed electron transfer mechanism of the vibrational frequencies of odorants could be easily suppressed by quantum effects of non-odorant molecular vibrational modes. As a result, these and other concerns about electron transfer at ORs, together with our extensive experimental data, argue against the plausibility of the vibration theory.« less

Eulerian frequency analysis of structural vibrations from high-speed video

DOE Office of Scientific and Technical Information (OSTI.GOV)

Venanzoni, Andrea; Siemens Industry Software NV, Interleuvenlaan 68, B-3001 Leuven; De Ryck, Laurent

An approach for the analysis of the frequency content of structural vibrations from high-speed video recordings is proposed. The techniques and tools proposed rely on an Eulerian approach, that is, using the time history of pixels independently to analyse structural motion, as opposed to Lagrangian approaches, where the motion of the structure is tracked in time. The starting point is an existing Eulerian motion magnification method, which consists in decomposing the video frames into a set of spatial scales through a so-called Laplacian pyramid [1]. Each scale — or level — can be amplified independently to reconstruct a magnified motionmore » of the observed structure. The approach proposed here provides two analysis tools or pre-amplification steps. The first tool provides a representation of the global frequency content of a video per pyramid level. This may be further enhanced by applying an angular filter in the spatial frequency domain to each frame of the video before the Laplacian pyramid decomposition, which allows for the identification of the frequency content of the structural vibrations in a particular direction of space. This proposed tool complements the existing Eulerian magnification method by amplifying selectively the levels containing relevant motion information with respect to their frequency content. This magnifies the displacement while limiting the noise contribution. The second tool is a holographic representation of the frequency content of a vibrating structure, yielding a map of the predominant frequency components across the structure. In contrast to the global frequency content representation of the video, this tool provides a local analysis of the periodic gray scale intensity changes of the frame in order to identify the vibrating parts of the structure and their main frequencies. Validation cases are provided and the advantages and limits of the approaches are discussed. The first validation case consists of the frequency content retrieval of the tip of a shaker, excited at selected fixed frequencies. The goal of this setup is to retrieve the frequencies at which the tip is excited. The second validation case consists of two thin metal beams connected to a randomly excited bar. It is shown that the holographic representation visually highlights the predominant frequency content of each pixel and locates the global frequencies of the motion, thus retrieving the natural frequencies for each beam.« less

Tonic vibration reflex in spasticity, Parkinson's disease, and normal subjects

PubMed Central

Burke, David; Andrews, Colin J.; Lance, James W.

1972-01-01

The tonic vibration reflex (TVR) has been studied in the quadriceps and triceps surae muscles of 34 spastic, 15 Parkinsonism, and 10 normal subjects. The TVR of spasticity develops rapidly, reaching a plateau level within 2-4 sec of the onset of vibration. The tonic contraction was often preceded by a phasic spike which appeared to be a vibration-induced equivalent of the tendon jerk. The initial phasic spike was usually followed by a silent period, and induced clonus in some patients. No correlation was found between the shape of the TVR and the site of the lesion in the central nervous system. The TVR of normal subjects and patients with Parkinsonism developed slowly, starting some seconds after the onset of vibration, and reaching a plateau level in 20-60 sec. A phasic spike was recorded occasionally in these subjects, but the subsequent tonic contraction followed the usual time course. Muscle stretch increased the quadriceps TVR of all subjects, including those with spasticity in whom the quadriceps stretch reflex decreased with increasing stretch. It is suggested that this difference between the tonic vibration reflex and the tonic stretch reflex arises from the selective activation of spindle primary endings by vibration, while both the primary and the secondary endings are responsive to muscle stretch. The TVR could be potentiated by reinforcement in some subjects. Potentiation outlasted the reinforcing manoeuvre, and was most apparent at short muscle lengths. As muscle stretch increased, thus producing a larger TVR, the degree of potentiation decreased. It is therefore suggested that the effects of reinforcement result at least partially from the activation of the fusimotor system. Since reinforcement potentiated the TVR of patients with spinal spasticity in whom a prominent clasp-knife phenomenon could be demonstrated, it is suggested that the effects of reinforcement are mediated by a descending pathway that traverses the anterior quadrant of the spinal cord. PMID:4261955

Noise-Induced Building Vibrations Caused by Concorde and Conventional Aircraft Operations at Dulles and Kennedy International Airports

NASA Technical Reports Server (NTRS)

Mayes, W. H.; Stephens, D. G.; Holmes, H. K.; Lewis, R. B.; Holliday, B. G.; Ward, D. W.; Deloach, R.; Cawthorn, J. M.; Finley, T. D.; Lynch, J. W.

1978-01-01

Outdoor and indoor noise levels resulting from aircraft flyovers and certain nonaircraft events were recorded, as were the associated vibration levels in the walls, windows, and floors at building test sites. In addition, limited subjective tests were conducted to examine the human detection and annoyance thresholds for building vibration and rattle caused by aircraft noise. Representative peak levels of aircraft noise-induced building vibrations are reported and comparisons are made with structural damage criteria and with vibration levels induced by common domestic events. In addition, results of a pilot study are reported which indicate the human detection threshold for noise-induced floor vibrations.

Vibration and acoustic frequency spectra for industrial process modeling using selective fusion multi-condition samples and multi-source features

NASA Astrophysics Data System (ADS)

Tang, Jian; Qiao, Junfei; Wu, ZhiWei; Chai, Tianyou; Zhang, Jian; Yu, Wen

2018-01-01

Frequency spectral data of mechanical vibration and acoustic signals relate to difficult-to-measure production quality and quantity parameters of complex industrial processes. A selective ensemble (SEN) algorithm can be used to build a soft sensor model of these process parameters by fusing valued information selectively from different perspectives. However, a combination of several optimized ensemble sub-models with SEN cannot guarantee the best prediction model. In this study, we use several techniques to construct mechanical vibration and acoustic frequency spectra of a data-driven industrial process parameter model based on selective fusion multi-condition samples and multi-source features. Multi-layer SEN (MLSEN) strategy is used to simulate the domain expert cognitive process. Genetic algorithm and kernel partial least squares are used to construct the inside-layer SEN sub-model based on each mechanical vibration and acoustic frequency spectral feature subset. Branch-and-bound and adaptive weighted fusion algorithms are integrated to select and combine outputs of the inside-layer SEN sub-models. Then, the outside-layer SEN is constructed. Thus, "sub-sampling training examples"-based and "manipulating input features"-based ensemble construction methods are integrated, thereby realizing the selective information fusion process based on multi-condition history samples and multi-source input features. This novel approach is applied to a laboratory-scale ball mill grinding process. A comparison with other methods indicates that the proposed MLSEN approach effectively models mechanical vibration and acoustic signals.

Shaking Youngsters and Shaken Adults: Female Beetles Eavesdrop on Larval Seed Vibrations to Make Egg-Laying Decisions

PubMed Central

Guedes, Raul Narciso C.; Yack, Jayne E.

2016-01-01

Egg-laying decisions are critical for insects, and particularly those competing for limited resources. Sensory information used by females to mediate egg-laying decisions has been reported to be primarily chemical, but the role of vibration has received little attention. We tested the hypothesis that vibrational cues produced by feeding larvae occupying a seed influences egg-laying decisions amongst female cowpea beetles. This hypothesis is supported by three lines of evidence using two strains of the cowpea beetle (Callosobruchus maculatus), an Indian strain with choosy females and aggressively competing larvae and a Brazilian strain with less choosy females and larvae exhibiting an “accommodating” type of competition. First, in free-choice bioassays of seed selection, choosy Indian females selected control seeds (free of eggs, larvae, or egg-laying marker) over seeds with live larvae (free of eggs and egg-laying marker), but did not discriminate between control seeds and those with dead larvae. In contrast, less choosy Brazilian females showed no preference for seeds containing live or dead larvae over controls. Second, laser-doppler vibrometer recordings confirmed that larvae feeding inside seeds generate vibrations that are available to the female during egg-laying decisions. Third, during dichotomous choice experiments where artificial vibrations approximating those produced by feeding larvae were played back during seed selection, Indian females preferred immobile control seeds over vibrating seeds, but Brazilian females showed no preference. These results support the hypothesis that females use larval vibrations in their egg-laying decisions; whether these vibrations are passive cues exploited by the female, or active signals that ‘steer’ the behaviour of the female is unknown. We propose that vibration cues and signals could be important for host selection in insects, particularly those laying on substrates where visual or chemical cues may be unreliable. This seems to be the case with females of the cowpea beetle since visual cues are not important and chemical egg-marking does not last more than two weeks, allowing vibration cues to improve discrimination of egg-laying substrate particularly by choosy females. PMID:26913508

Lifetime-vibrational interference effects in resonantly excited x-ray emission spectra of CO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skytt, P.; Glans, P.; Gunnelin, K.

1997-04-01

The parity selection rule for resonant X-ray emission as demonstrated for O{sub 2} and N{sub 2} can be seen as an effect of interference between coherently excited degenerate localized core states. One system where the core state degeneracy is not exact but somewhat lifted was previously studied at ALS, namely the resonant X-ray emission of amino-substituted benzene (aniline). It was shown that the X-ray fluorescence spectrum resulting from excitation of the C1s at the site of the {open_quotes}aminocarbon{close_quotes} could be described in a picture separating the excitation and the emission processes, whereas the spectrum corresponding to the quasi-degenerate carbons couldmore » not. Thus, in this case it was necessary to take interference effects between the quasi-degenerate intermediate core excited states into account in order to obtain agreement between calculations and experiment. The different vibrational levels of core excited states in molecules have energy splittings which are of the same order of magnitude as the natural lifetime broadening of core excitations in the soft X-ray range. Therefore, lifetime-vibrational interference effects are likely to appear and influence the band shapes in resonant X-ray emission spectra. Lifetime-vibrational interference has been studied in non-resonant X-ray emission, and in Auger spectra. In this report the authors discuss results of selectively excited soft X-ray fluorescence spectra of molecules, where they focus on lifetime-interference effects appearing in the band shapes.« less

Benefits of Spacecraft Level Vibration Testing

NASA Technical Reports Server (NTRS)

Gordon, Scott; Kern, Dennis L.

2015-01-01

NASA-HDBK-7008 Spacecraft Level Dynamic Environments Testing discusses the approaches, benefits, dangers, and recommended practices for spacecraft level dynamic environments testing, including vibration testing. This paper discusses in additional detail the benefits and actual experiences of vibration testing spacecraft for NASA Goddard Space Flight Center (GSFC) and Jet Propulsion Laboratory (JPL) flight projects. JPL and GSFC have both similarities and differences in their spacecraft level vibration test approach: JPL uses a random vibration input and a frequency range usually starting at 5 Hz and extending to as high as 250 Hz. GSFC uses a sine sweep vibration input and a frequency range usually starting at 5 Hz and extending only to the limits of the coupled loads analysis (typically 50 to 60 Hz). However, both JPL and GSFC use force limiting to realistically notch spacecraft resonances and response (acceleration) limiting as necessary to protect spacecraft structure and hardware from exceeding design strength capabilities. Despite GSFC and JPL differences in spacecraft level vibration test approaches, both have uncovered a significant number of spacecraft design and workmanship anomalies in vibration tests. This paper will give an overview of JPL and GSFC spacecraft vibration testing approaches and provide a detailed description of spacecraft anomalies revealed.

Vibration Penalty Estimates for Indoor Annoyance Caused by Sonic Boom

NASA Technical Reports Server (NTRS)

Rathsam, Jonathan; Klos, Jacob

2016-01-01

Commercial supersonic flight is currently forbidden over land because sonic booms have historically caused unacceptable annoyance levels in overflown communities. NASA is providing data and expertise to noise regulators as they consider relaxing the ban for future quiet supersonic aircraft. One key objective is a predictive model for indoor annoyance based on factors such as noise and indoor vibration levels. The current study quantified the increment in indoor sonic boom annoyance when sonic booms can be felt directly through structural vibrations in addition to being heard. A shaker mounted below each chair in the sonic boom simulator emulated vibrations transmitting through the structure to that chair. The vibration amplitudes were determined from numeric models of a large range of residential structures excited by the same sonic boom waveforms used in the experiment. The analysis yielded vibration penalties, which are the increments in sound level needed to increase annoyance as much as the vibration does. For sonic booms at acoustic levels from 75 to 84 dB Perceived Level, vibration signals with lower amplitudes (+1 sigma) yielded penalties from 0 to 5 dB, and vibration signals with higher amplitudes (+3 sigma) yielded penalties from 6 to 10 dB.

Decreasing sound and vibration during ground transport of infants with very low birth weight.

PubMed

Prehn, J; McEwen, I; Jeffries, L; Jones, M; Daniels, T; Goshorn, E; Marx, C

2015-02-01

To measure the effectiveness of modifications to reduce sound and vibration during interhospital ground transport of a simulated infant with very low birth weight (VLBW) and a gestational age of 30 weeks, a period of high susceptibility to germinal matrix and intraventricular hemorrhage. Researchers measured vibration and sound levels during infant transport, and compared levels after modifications to the transport incubator mattresses, addition of vibration isolators under incubator wheels, addition of mass to the incubator mattress and addition of incubator acoustic cover. Modifications did not decrease sound levels inside the transport incubator during transport. The combination of a gel mattress over an air chambered mattress was effective in decreasing vibration levels for the 1368 g simulated infant. Transport mattress effectiveness in decreasing vibration is influenced by infant weight. Modifications that decrease vibration for infants weighing 2000 g are not effective for infants with VLBW. Sound levels are not affected by incubator covers, suggesting that sound is transmitted into the incubator as a low-frequency vibration through the incubator's contact with the ambulance. Medical transportation can apply industrial methods of vibration and sound control to protect infants with VLBW from excessive physical strain of transport during vulnerable periods of development.

Systematic review of whole body vibration exercises in the treatment of cerebral palsy: Brief report.

PubMed

Sá-Caputo, Danúbia C; Costa-Cavalcanti, Rebeca; Carvalho-Lima, Rafaelle P; Arnóbio, Adriano; Bernardo, Raquel M; Ronikeile-Costa, Pedro; Kutter, Cristiane; Giehl, Paula M; Asad, Nasser R; Paiva, Dulciane N; Pereira, Heloisa V F S; Unger, Marianne; Marin, Pedro J; Bernardo-Filho, Mario

2016-10-01

Whole body vibration (WBV) is increasingly being used to improve balance and motor function and reduce the secondary complications associated with cerebral palsy (CP). The purpose of this study was to systematically appraise published research regarding the effects of static and/or dynamic exercise performed on a vibrating platform on gait, strength, spasticity and bone mineral density (BMD) within this population. Systematic searches of six electronic databases identified five studies that met our inclusion criteria (2 at Level II and 3 at Level III-2). Studies were analysed to determine: (a) participant characteristics; (b) optimal exercise and WBV treatment protocol; (c) effect on gait, strength, spasticity and BMD; and (d) the outcome measures used to evaluate effect. As data was not homogenous a meta-analysis was not possible. Several design limitations were identified and intervention protocols are poorly described. The effects on strength, gait, spasticity and BMD in persons with CP remain inconclusive with weak evidence that WBV may improve selected muscle strength and gait parameters and that prolonged exposure may improve BMD; there is currently no evidence that WBV can reduce spasticity. The evidence for exercise performed on a vibrating platform on mobility, strength, spasticity and BMD in CP remains scant and further larger scale investigations with controlled parameters to better understand the effects of WBV exercises in this population is recommended.

Frequency and zero-point vibrational energy scale factors for double-hybrid density functionals (and other selected methods): can anharmonic force fields be avoided?

PubMed

Kesharwani, Manoj K; Brauer, Brina; Martin, Jan M L

2015-03-05

We have obtained uniform frequency scaling factors λ(harm) (for harmonic frequencies), λ(fund) (for fundamentals), and λ(ZPVE) (for zero-point vibrational energies (ZPVEs)) for the Weigend-Ahlrichs and other selected basis sets for MP2, SCS-MP2, and a variety of DFT functionals including double hybrids. For selected levels of theory, we have also obtained scaling factors for true anharmonic fundamentals and ZPVEs obtained from quartic force fields. For harmonic frequencies, the double hybrids B2PLYP, B2GP-PLYP, and DSD-PBEP86 clearly yield the best performance at RMSD = 10-12 cm(-1) for def2-TZVP and larger basis sets, compared to 5 cm(-1) at the CCSD(T) basis set limit. For ZPVEs, again, the double hybrids are the best performers, reaching root-mean-square deviations (RMSDs) as low as 0.05 kcal/mol, but even mainstream functionals like B3LYP can get down to 0.10 kcal/mol. Explicitly anharmonic ZPVEs only are marginally more accurate. For fundamentals, however, simple uniform scaling is clearly inadequate.

Vibration testing of the JE-M-604-4-IUE rocket motor (Thiokol P/N E 28639-03)

NASA Technical Reports Server (NTRS)

Alt, R. E.; Tosh, J. T.

1976-01-01

The NASA International Ultraviolet Explorer (IUE) rocket motor (TE-M-604-4), a solid fuel, spherical rocket motor, was vibration tested in the Impact, Vibration, and Acceleration (IVA) Test Unit of the von Karman Gas Dynamics Facility (VKF). The objective of the test program was to subject the motor to qualification levels of sinusoidal and random vibration prior to the altitude firing of the motor in the Propulsion Development Test Cell (T-3), Engine Test Facility (ETF), AEDC. The vibration testing consisted of a low level sine survey from 5 to 2,000 Hz, followed by a qualification level sine sweep and qualification level random vibration. A second low level sine survey followed the qualification level testing. This sequence of testing was accomplished in each of three orthogonal axes. No motor problems were observed due to the imposition of these dynamic environments.

Vibronic coupling and selectivity of vibrational excitation in the negative ion resonances of ozone

NASA Astrophysics Data System (ADS)

Allan, Michael; Popovic̀, Duška B.

1997-04-01

A recent experimental paper reported two shape resonances in electron impact on ozone, A 1 and B 2, both causing vibrational excitation with a distinct pattern of selectivity. The present Letter attempts to rationalize this selectivity using approximate potential curves, calculated for the A 1 and B 2 resonances by adding the SCF energy of neutral ozone to electron attachment energies calculated from ab initio virtual orbital energies using the Koopmans' theorem and an empirical scaling relation. The slopes of the curves explain the efficient excitation of the symmetric stretch by both resonances and the lack of the bending excitation by the B 2 resonance. The A 1 and B 2 resonances are strongly coupled by the b 2 antisymmetric stretch vibration, causing a double minimum on the lower surface. Nonadiabatic effects caused by the strong vibronic coupling explain the observed excitation of the antisymmetric stretch vibration.

Whole-body vibration exposure in sport: four relevant cases.

PubMed

Tarabini, Marco; Saggin, Bortolino; Scaccabarozzi, Diego

2015-01-01

This study investigates the whole-body vibration exposure in kite surfing, alpine skiing, snowboarding and cycling. The vibration exposure was experimentally evaluated following the ISO 2631 guidelines. Results evidenced that the most critical axis is the vertical one. The weighted vibration levels are always larger than 2.5 m/s(2) and the vibration dose values are larger than 25 m/s(1.75). The exposure limit values of the EU directive are reached after 8-37 min depending on the sport. The vibration magnitude is influenced by the athletes' speed, by their skill level and sometimes by the equipment. The large vibration values suggest that the practice of sport activities may be a confounding factor in the aetiology of vibration-related diseases. The vibration exposure in some sports is expected to be large, but has never been quantified in the literature. Results of experiments performed in cycling, alpine and water sports outlined vibration levels exceeding the EU standard limit values.

Comparison of Annoyance from Railway Noise and Railway Vibration

PubMed Central

Gidlöf-Gunnarsson, Anita; Gustavsson, Sara

2017-01-01

The aim of this study is to compare vibration exposure to noise exposure from railway traffic in terms of equal annoyance, i.e., to determine when a certain noise level is equally annoying as a corresponding vibration velocity. Based on questionnaire data from the Train Vibration and Noise Effects (TVANE) research project from residential areas exposed to railway noise and vibration, the dose response relationship for annoyance was estimated. By comparing the relationships between exposure and annoyance for areas both with and without significant vibration exposure, the noise levels and vibration velocities that had an equal probability of causing annoyance was determined using logistic regression. The comparison gives a continuous mapping between vibration velocity in the ground and a corresponding noise level at the facade that are equally annoying. For equivalent noise level at the facade compared to maximum weighted vibration velocity in the ground the probability of annoyance is approximately 20% for 59 dB or 0.48 mm/s, and about 40% for 63 dB or 0.98 mm/s. PMID:28753921

Quantum coherence selective 2D Raman–2D electronic spectroscopy

PubMed Central

Spencer, Austin P.; Hutson, William O.; Harel, Elad

2017-01-01

Electronic and vibrational correlations report on the dynamics and structure of molecular species, yet revealing these correlations experimentally has proved extremely challenging. Here, we demonstrate a method that probes correlations between states within the vibrational and electronic manifold with quantum coherence selectivity. Specifically, we measure a fully coherent four-dimensional spectrum which simultaneously encodes vibrational–vibrational, electronic–vibrational and electronic–electronic interactions. By combining near-impulsive resonant and non-resonant excitation, the desired fifth-order signal of a complex organic molecule in solution is measured free of unwanted lower-order contamination. A critical feature of this method is electronic and vibrational frequency resolution, enabling isolation and assignment of individual quantum coherence pathways. The vibronic structure of the system is then revealed within an otherwise broad and featureless 2D electronic spectrum. This method is suited for studying elusive quantum effects in which electronic transitions strongly couple to phonons and vibrations, such as energy transfer in photosynthetic pigment–protein complexes. PMID:28281541

A diagnostic signal selection scheme for planetary gearbox vibration monitoring under non-stationary operational conditions

NASA Astrophysics Data System (ADS)

Feng, Ke; Wang, KeSheng; Zhang, Mian; Ni, Qing; Zuo, Ming J.

2017-03-01

The planetary gearbox, due to its unique mechanical structures, is an important rotating machine for transmission systems. Its engineering applications are often in non-stationary operational conditions, such as helicopters, wind energy systems, etc. The unique physical structures and working conditions make the vibrations measured from planetary gearboxes exhibit a complex time-varying modulation and therefore yield complicated spectral structures. As a result, traditional signal processing methods, such as Fourier analysis, and the selection of characteristic fault frequencies for diagnosis face serious challenges. To overcome this drawback, this paper proposes a signal selection scheme for fault-emphasized diagnostics based upon two order tracking techniques. The basic procedures for the proposed scheme are as follows. (1) Computed order tracking is applied to reveal the order contents and identify the order(s) of interest. (2) Vold-Kalman filter order tracking is used to extract the order(s) of interest—these filtered order(s) constitute the so-called selected vibrations. (3) Time domain statistic indicators are applied to the selected vibrations for faulty information-emphasized diagnostics. The proposed scheme is explained and demonstrated in a signal simulation model and experimental studies and the method proves to be effective for planetary gearbox fault diagnosis.

Vibronic transitions in the alkali-metal (Li, Na, K, Rb) - alkaline-earth-metal (Ca, Sr) series: A systematic analysis of de-excitation mechanisms based on the graphical mapping of Frank-Condon integrals

NASA Astrophysics Data System (ADS)

Pototschnig, Johann V.; Meyer, Ralf; Hauser, Andreas W.; Ernst, Wolfgang E.

2017-02-01

Research on ultracold molecules has seen a growing interest recently in the context of high-resolution spectroscopy and quantum computation. After forming weakly bound molecules from atoms in cold collisions, the preparation of molecules in low vibrational levels of the ground state is experimentally challenging, and typically achieved by population transfer using excited electronic states. Accurate potential energy surfaces are needed for a correct description of processes such as the coherent de-excitation from the highest and therefore weakly bound vibrational levels in the electronic ground state via couplings to electronically excited states. This paper is dedicated to the vibrational analysis of potentially relevant electronically excited states in the alkali-metal (Li, Na, K, Rb)- alkaline-earth metal (Ca,Sr) diatomic series. Graphical maps of Frank-Condon overlap integrals are presented for all molecules of the group. By comparison to overlap graphics produced for idealized potential surfaces, we judge the usability of the selected states for future experiments on laser-enhanced molecular formation from mixtures of quantum degenerate gases.

Journal of Engineering Thermophysics (Selected Articles),

DTIC Science & Technology

1983-05-13

compressor, prediction of unsteady vibration , and prevention of unsteady vibration . This test was undergone on a turbojet engine. The paper stresses the...induce unsteady engine vibration . While studying the effect of inlet anomaly and variation of the first stage nozzle area of the turbine, the engine...constant revolution speed curve until unsteady vibration or stall appeared. In studying the influence of the starting sequence, starting was

Vibrational dynamics (IR, Raman, NRVS) and DFT study of new antitumor tetranuclearstannoxanecluster, Sn(IV)$-$oxo$-$${di$$-$o$-$vanillin} dimethyl dichloride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arjmand, F.; Sharma, S.; Usman, M.

2016-06-21

The vibrational dynamics of a newly synthesized tetrastannoxane was characterized with a combination of experimental (Raman, IR and tin-based nuclear resonance vibrational spectroscopy) and computational (DFT/B3LYP) methods, with an emphasis on the vibrations of the tin sites. The cytotoxic activity revealed a significant regression selectively against the human pancreatic cell lines.

In-Flight Vibration Environment of the NASA F-15B Flight Test Fixture

NASA Technical Reports Server (NTRS)

Corda, Stephen; Franz, Russell J.; Blanton, James N.; Vachon, M. Jake; DeBoer, James B.

2002-01-01

Flight vibration data are analyzed for the NASA F-15B/Flight Test Fixture II test bed. Understanding the in-flight vibration environment benefits design and integration of experiments on the test bed. The power spectral density (PSD) of accelerometer flight data is analyzed to quantify the in-flight vibration environment from a frequency of 15 Hz to 1325 Hz. These accelerometer data are analyzed for typical flight conditions and maneuvers. The vibration data are compared to flight-qualification random vibration test standards. The PSD levels in the lateral axis generally are greater than in the longitudinal and vertical axes and decrease with increasing frequency. At frequencies less than approximately 40 Hz, the highest PSD levels occur during takeoff and landing. Peaks in the PSD data for the test fixture occur at approximately 65, 85, 105-110, 200, 500, and 1000 Hz. The pitch-pulse and 2-g turn maneuvers produce PSD peaks at 115 Hz. For cruise conditions, the PSD level of the 85-Hz peak is greatest for transonic flight at Mach 0.9. From 400 Hz to 1325 Hz, the takeoff phase has the highest random vibration levels. The flight-measured vibration levels generally are substantially lower than the random vibration test curve.

NASA Instep/mdmsc Jitter Suppression Experiment (JITTER)

NASA Technical Reports Server (NTRS)

White, Edward V.

1992-01-01

The objectives are the following: (1) to develop and demonstrate in-space performance of both passive and active damping systems for suppression of micro-amplitude vibration on an actual application structure and operate despite uncertain dynamics and uncertain disturbance characteristics; and (2) to correlate ground and in-space performance - the performance metric is vibration attenuation. The goals are to achieve vibration suppression equivalent to 5 percent passive damping in selected models and 15 percent active damping in selected modes. Various aspects of this experiment are presented in viewgraph form.

Effects of whole body vibration on pulmonary function, functional exercise capacity and quality of life in people with chronic obstructive pulmonary disease: a systematic review.

PubMed

Yang, Xiaotian; Zhou, Yujing; Wang, Pu; He, Chengqi; He, Hongchen

2016-05-01

To examine the effect of whole-body vibration in enhancing pulmonary function, functional exercise capacity and quality of life in people with chronic obstructive pulmonary disease and examine its safety. Randomized controlled trials examining the effects of whole body vibration among people with chronic obstructive pulmonary disease were identified by two independent researchers. Articles were excluded if they were studies on people with other primary diagnosis, abstracts published in the conferences or books. PEDro scale was used to assess the methodological quality of the selected studies. We evaluated the level of evidence by using the GRADE approach. The results were extracted by two researchers and confirmed by the third researcher if disagreement existed. Sources included Cochrane Central Register of Controlled Trials, PubMed, CINAHL, EMBASE, PEDro, AMED, PsycINFO, ClinicalTrials.gov, Current Controlled Trials and reference lists of all relevant articles. Four studies involving 206 participants were included in this systematic review. Methodological quality was rated as good for two studies. No great benefits on pulmonary function were found in whole body vibration treatment group. Two studies showed that quality of life was improved in people with chronic obstructive pulmonary disease. Whole body vibration led to significant improvements in functional exercise capacity measured with six minutes walking test. Nearly no adverse events were observed. Whole body vibration may improve functional exercise capacity and quality of life in people with chronic obstructive pulmonary disease. There was insufficient evidence to prove the effects of whole body vibration on pulmonary function. © The Author(s) 2015.

Centaur liquid oxygen boost pump vibration test

NASA Technical Reports Server (NTRS)

Tang, H. M.

1975-01-01

The Centaur LOX boost pump was subjected to both the simulated Titan Centaur proof flight and confidence demonstration vibration test levels. For each test level, both sinusoidal and random vibration tests were conducted along each of the three orthogonal axes of the pump and turbine assembly. In addition to these tests, low frequency longitudinal vibration tests for both levels were conducted. All tests were successfully completed without damage to the boost pump.

Analysis of Vibration and Noise of Construction Machinery Based on Ensemble Empirical Mode Decomposition and Spectral Correlation Analysis Method

NASA Astrophysics Data System (ADS)

Chen, Yuebiao; Zhou, Yiqi; Yu, Gang; Lu, Dan

In order to analyze the effect of engine vibration on cab noise of construction machinery in multi-frequency bands, a new method based on ensemble empirical mode decomposition (EEMD) and spectral correlation analysis is proposed. Firstly, the intrinsic mode functions (IMFs) of vibration and noise signals were obtained by EEMD method, and then the IMFs which have the same frequency bands were selected. Secondly, we calculated the spectral correlation coefficients between the selected IMFs, getting the main frequency bands in which engine vibration has significant impact on cab noise. Thirdly, the dominated frequencies were picked out and analyzed by spectral analysis method. The study result shows that the main frequency bands and dominated frequencies in which engine vibration have serious impact on cab noise can be identified effectively by the proposed method, which provides effective guidance to noise reduction of construction machinery.

Short term response of insulin, glucose, growth hormone and corticosterone to acute vibration in rats.

NASA Technical Reports Server (NTRS)

Dolkas, C. B.; Leon, H. A.; Chackerian, M.

1971-01-01

Study carried out to obtain some notion of the initial phasing and interactive effects among some hormones known to be responsive to vibration stress. Sprague-Dawley derived rats were exposed to the acute effects of confinement and confinement with lateral (plus or minus G sub y) vibration. The coincident monitoring of glucose, insulin, growth hormone, and corticosterone plasma levels, during and immediately subsequent to exposure to brief low level vibration, exhibits the effects of inhibition of insulin release by epinephrine. The ability of insulin (IRI) to return rapidly to basal levels, from appreciably depressed levels during vibration, in the face of elevated levels of glucose is also shown. Corticosterone responds with almost equal rapidity, but in opposite phase to the IRI. The immuno-assayable growth hormone (IGH) dropped from a basal level of 32 ng/ml to 7.3 ng/ml immediately subsequent to vibration and remained at essentially that level throughout the experiment (60 min). Whether these levels represent a real fall in the rat or whether they merely follow the immuno-logically deficient form is still in question.

Anharmonic Resonances among Low-Lying Vibrational Levels of Methyl Iso-Cyanide (H_3CNC)

NASA Astrophysics Data System (ADS)

Pracna, P.; Urban, J.; Urban, V. S.; Varga, J.; Horneman, V.-M.

2010-06-01

Vibrational levels up to 1000 wn of H_3C-N≡C are currently studied in FTIR spectra together with rotational transitions within these levels. This investigation comprises the low-lying excited vibrational levels of the CNC doubly degenerate bending vibration v8=1^± 1 (267.3 wn), v8=20,± 2 (524.6 wn (A), 545.3 wn (E)), and v8=3^± 1,± 3 (792.5 wn (A1+A2), 833.9 wn (E)), respectively, and the next higher fundamental level of the C-N valence vibration v4=1 (945 wn). All these vibrational levels exhibit cubic and quartic anharmonic resonances localized to moderate values of the rotational quantum number K≤10. Therefore the system of rovibrational levels has to be treated as a global polyad in order to describe all the available data quantitatively. The ground state constants have been improved considerably by extending the assignments to higher J/K rotational states both in the purely rotational spectra recorded in the ground vibrational level and in the ground state combination differences generated from the wavenumbers assigned in the fundamental ν_4 band. Similarities and differences with respect to isoelectronic molecules CH_3CN and CH_3CCH are discussed.

Ab Initio Vibrational Levels For HO2 and Vibrational Splittings for Hydrogen Atom Transfer

NASA Technical Reports Server (NTRS)

Barclay, V. J.; Dateo, Christopher E.; Hamilton, I. P.; Arnold, James O. (Technical Monitor)

1994-01-01

We calculate vibrational levels and wave functions for HO2 using the recently reported ab initio potential energy surface of Walch and Duchovic. There is intramolecular hydrogen atom transfer when the hydrogen atom tunnels through a T-shaped saddle point separating two equivalent equilibrium geometries, and correspondingly, the energy levels are split. We focus on vibrational levels and wave functions with significant splitting. The first three vibrational levels with splitting greater than 2/cm are (15 0), (0 7 1) and (0 8 0) where V(sub 2) is the O-O-H bend quantum number. We discuss the dynamics of hydrogen atom transfer; in particular, the O-O distances at which hydrogen atom transfer is most probable for these vibrational levels. The material of the proposed presentation was reviewed and the technical content will not reveal any information not already in the public domain and will not give any foreign industry or government a competitive advantage.

Selective detection of crystalline cellulose in plant cell walls with sum-frequency-generation (SFG) vibration spectroscopy.

PubMed

Barnette, Anna L; Bradley, Laura C; Veres, Brandon D; Schreiner, Edward P; Park, Yong Bum; Park, Junyeong; Park, Sunkyu; Kim, Seong H

2011-07-11

The selective detection of crystalline cellulose in biomass was demonstrated with sum-frequency-generation (SFG) vibration spectroscopy. SFG is a second-order nonlinear optical response from a system where the optical centrosymmetry is broken. In secondary plant cell walls that contain mostly cellulose, hemicellulose, and lignin with varying concentrations, only certain vibration modes in the crystalline cellulose structure can meet the noninversion symmetry requirements. Thus, SFG can be used to detect and analyze crystalline cellulose selectively in lignocellulosic biomass without extraction of noncellulosic species from biomass or deconvolution of amorphous spectra. The selective detection of crystalline cellulose in lignocellulosic biomass is not readily achievable with other techniques such as XRD, solid-state NMR, IR, and Raman analyses. Therefore, the SFG analysis presents a unique opportunity to reveal the cellulose crystalline structure in lignocellulosic biomass.

Effects of Short-Period Whole-Body Vibration of 20 Hz on Selected Blood Biomarkers in Wistar Rats.

PubMed

Monteiro, Milena de Oliveira Bravo; de Sá-Caputo, Danúbia da Cunha; Carmo, Fernanda Santos do; Bernardo, Raquel Mattos; Pacheco, Raphaelle; Arnóbio, Adriano; Guimarães, Carlos Alberto Sampaio; Bernardo, Luciana Camargo; Santos-Filho, Sebastião David; Asad, Nasser Ribeiro; Unger, Marianne; Marin, Pedro Jesus; Bernardo-Filho, Mario

2015-08-31

There is a growing interest in the use of vibration generated by oscillating/vibratory platforms - also known as whole-body vibration (WBV) - for achieving therapeutic, preventative and/or physical performance goals. This study investigated the effects of vibration generated by an oscillating platform on the concentration of blood biomarkers in rats. Wistar rats (n = 8) were divided in 2 groups, sedated and individually positioned on an oscillating platform. The experimental group (EG) was subjected to vibrations of 20 Hz for one min per day for one week while the control group (CG) experienced no vibration. Samples of heparinized whole blood were drawn by cardiac puncture for biochemical analysis. Concentrations of total cholesterol, triglycerides, HDL, LDL, VLDL, glucose, CK, albumin, alkaline phosphates, TGP, TGO, γGT, lipase, amylase, urea and creatinine were determined. White blood cell count and a platelet hemogram were also performed. Following seven sessions of exposure to the vibration, a significant (P < 0.05) reduction in γGT, VLDL and leukocytes was found. A weekly 1-min/day exposure of 20 Hz vibration can was shown to alter the concentrations of selected blood biomarkers in rats. The action mechanism associated with these effects seems highly complex, but the findings might contribute to the understanding of these mechanisms related to the exposure to 20 Hz vibration.

Vibration ride comfort criteria

NASA Technical Reports Server (NTRS)

Dempsey, T. K.; Leatherwood, J. D.

1976-01-01

Results are presented for an experimental study directed to derive equal vibration discomfort curves, to determine the influence of vibration masking in order to account for the total discomfort of any random vibration, and to develop a scale of total vibration discomfort in the case of human response to whole-body vertical vibration. Discomfort is referred to as a subjective discomfort associated with the acceleration level of a particular frequency band. It is shown that passenger discomfort to whole-body vibration increases linearly with acceleration level for each frequency. Empirical data provide a mechanism for determining the degree of masking (or summation) of the discomfort of multiple frequency vibration. A scale for the prediction of passenger discomfort is developed.

Hand-arm vibration syndrome in South African gold miners.

PubMed

Nyantumbu, Busi; Barber, Chris M; Ross, Mary; Curran, Andrew D; Fishwick, David; Dias, Belinda; Kgalamono, Spo; Phillips, James I

2007-01-01

Hand-arm vibration syndrome (HAVS) is associated with the use of hand-held vibrating tools. Affected workers may experience symptoms of tingling, numbness, loss of grip strength and pain. Loss of dexterity may impair everyday activities, and potentially increase the risk of occupational accidents. Although high vibration levels (up to 31 m/s(2)) have been measured in association with rock drills, HAVS has not been scientifically evaluated in the South African mining industry. The aim of this study was to determine the prevalence and severity of HAVS in South African gold miners, and to identify the tools responsible. A cross-sectional study was conducted in a single South African gold-mine. Participants were randomly selected from mineworkers returning from annual leave, comprising 156 subjects with occupational exposure to vibration, and 140 workers with no exposure. Miners who consented to participate underwent a clinical HAVS assessment following the UK Health and Safety Laboratory protocol. The prevalence of HAVS in vibration-exposed gold miners was 15%, with a mean latent period of 5.6 years. Among the non-exposed comparison group, 5% had signs and symptoms indistinguishable from HAVS. This difference was statistically significant (P < 0.05). All the cases of HAVS gave a history of exposure to rock drills. The study has diagnosed the first cases of HAVS in the South African mining industry. The prevalence of HAVS was lower than expected, and possible explanations for this may include a survivor population, and lack of vascular symptom reporting due to warm-ambient temperatures.

Exploring Solvent Shape and Function Using - and Isomer-Selective Vibrational Spectroscopy

NASA Astrophysics Data System (ADS)

Johnson, Mark

2010-06-01

We illustrate the new types of information than can be obtained through isomer-selective ``hole-burning'' spectroscopy carried out in the vibrational manifolds of Ar-tagged cluster ions. Three examples of increasing complexity will be presented where the changes in a solute ion are correlated with different morphologies of a surrounding solvent cage. In the first, we discuss the weak coupling limit where different hydration morphologies lead to small distortions of a covalent ion. We then introduce the more interesting case of the hydrated electron, where different shapes of the water network lead to dramatic changes in the extent of delocalization in the diffuse excess electron cloud. We then turn to the most complex case involving hydration of the nitrosonium ion, where different arrangements of the same number of water molecules span the range in behavior from simple solvation to actively causing a chemical reaction. The latter results are particularly interesting as they provide a microscopic, molecular-level picture of the ``solvent coordinate'' commonly used to describe solvent mediated processes.

New insights for mesospheric OH: multi-quantum vibrational relaxation as a driver for non-local thermodynamic equilibrium

PubMed Central

Kalogerakis, Konstantinos S.; Matsiev, Daniel; Cosby, Philip C.; Dodd, James A.; Falcinelli, Stefano; Hedin, Jonas; Kutepov, Alexander A.; Noll, Stefan; Panka, Peter A.; Romanescu, Constantin; Thiebaud, Jérôme E.

2018-01-01

The question of whether mesospheric OH(υ) rotational population distributions are in equilibrium with the local kinetic temperature has been debated over several decades. Despite several indications for the existence of non-equilibrium effects, the general consensus has been that emissions originating from low rotational levels are thermalized. Sky spectra simultaneously observing several vibrational levels demonstrated reproducible trends in the extracted OH(υ) rotational temperatures as a function of vibrational excitation. Laboratory experiments provided information on rotational energy transfer and direct evidence for fast multi-quantum OH(high-υ) vibrational relaxation by O atoms. We examine the relationship of the new relaxation pathways with the behavior exhibited by OH(υ) rotational population distributions. Rapid OH(high-υ) + O multi-quantum vibrational relaxation connects high and low vibrational levels and enhances the hot tail of the OH(low-υ) rotational distributions. The effective rotational temperatures of mesospheric OH(υ) are found to deviate from local thermodynamic equilibrium for all observed vibrational levels. PMID:29503514

Experimental investigation of jet pulse control on flexible vibrating structures

NASA Astrophysics Data System (ADS)

Karaiskos, Grigorios; Papanicolaou, Panos; Zacharopoulos, Dimitrios

2016-08-01

The feasibility of applying on-line fluid jet pulses to actively control the vibrations of flexible structures subjected to harmonic and earthquake-like base excitations provided by a shake table is explored. The operating principles and capabilities of the control system applied have been investigated in a simplified small-scale laboratory model that is a mass attached at the top free end of a vertical flexible slender beam with rectangular cross-section, the other end of which is mounted on an electrodynamic shaker. A pair of opposite jets placed on the mass at the top of the cantilever beam applied the appropriate forces by ejecting pressurized air pulses controlled by on/off solenoid electro-valves via in house developed control software, in order to control the vibration caused by harmonic, periodic and random excitations at pre-selected frequency content provided by the shaker. The dynamics of the structure was monitored by accelerometers and the jet impulses by pressure sensors. The experimental results have demonstrated the effectiveness and reliability of Jet Pulse Control Systems (JPCS). It was verified that the measured root mean square (RMS) vibration levels of the controlled structure from harmonic and earthquake base excitations, could be reduced by approximately 50% and 33% respectively.

Tool-specific performance of vibration-reducing gloves for attenuating palm-transmitted vibrations in three orthogonal directions

PubMed Central

Dong, Ren G.; Welcome, Daniel E.; Peterson, Donald R.; Xu, Xueyan S.; McDowell, Thomas W.; Warren, Christopher; Asaki, Takafumi; Kudernatsch, Simon; Brammer, Antony

2015-01-01

Vibration-reducing (VR) gloves have been increasingly used to help reduce vibration exposure, but it remains unclear how effective these gloves are. The purpose of this study was to estimate tool-specific performances of VR gloves for reducing the vibrations transmitted to the palm of the hand in three orthogonal directions (3-D) in an attempt to assess glove effectiveness and aid in the appropriate selection of these gloves. Four typical VR gloves were considered in this study, two of which can be classified as anti-vibration (AV) gloves according to the current AV glove test standard. The average transmissibility spectrum of each glove in each direction was synthesized based on spectra measured in this study and other spectra collected from reported studies. More than seventy vibration spectra of various tools or machines were considered in the estimations, which were also measured in this study or collected from reported studies. The glove performance assessments were based on the percent reduction of frequency-weighted acceleration as is required in the current standard for assessing the risk of vibration exposures. The estimated tool-specific vibration reductions of the gloves indicate that the VR gloves could slightly reduce (<5%) or marginally amplify (<10%) the vibrations generated from low-frequency (<25 Hz) tools or those vibrating primarily along the axis of the tool handle. With other tools, the VR gloves could reduce palm-transmitted vibrations in the range of 5%–58%, primarily depending on the specific tool and its vibration spectra in the three directions. The two AV gloves were not more effective than the other gloves with some of the tools considered in this study. The implications of the results are discussed. Relevance to industry Hand-transmitted vibration exposure may cause hand-arm vibration syndrome. Vibration-reducing gloves are considered as an alternative approach to reduce the vibration exposure. This study provides useful information on the effectiveness of the gloves when used with many tools for reducing the vibration transmitted to the palm in three directions. The results can aid in the appropriate selection and use of these gloves. PMID:26726275

Measuring the internal energies of species emitted from hypervelocity nanoprojectile impacts on surfaces using recalibrated benzylpyridinium probe ions

NASA Astrophysics Data System (ADS)

DeBord, J. Daniel; Verkhoturov, Stanislav V.; Perez, Lisa M.; North, Simon W.; Hall, Michael B.; Schweikert, Emile A.

2013-06-01

We present herein a framework for measuring the internal energy distributions of vibrationally excited molecular ions emitted from hypervelocity nanoprojectile impacts on organic surfaces. The experimental portion of this framework is based on the measurement of lifetime distributions of "thermometer" benzylpyridinium ions dissociated within a time of flight mass spectrometer. The theoretical component comprises re-evaluation of the fragmentation energetics of benzylpyridinium ions at the coupled-cluster singles and doubles with perturbative triples level. Vibrational frequencies for the ground and transition states of select molecules are reported, allowing for a full description of vibrational excitations of these molecules via Rice-Ramsperger-Kassel-Marcus unimolecular fragmentation theory. Ultimately, this approach is used to evaluate the internal energy distributions from the measured lifetime distributions. The average internal energies of benzylpyridinium ions measured from 440 keV Au400+4 impacts are found to be relatively low (˜0.24 eV/atom) when compared with keV atomic bombardment of surfaces (1-2 eV/atom).

Multiphoton Ionization Mass and Photoelectron Spectroscopy.

DTIC Science & Technology

1984-07-01

tracted information about ion vibrational energy levels. Molecules studted include benzene, toluene, aniline, paradifluorobenzene, nitric oxide ...molecules or subgroups and not to others. Ion specific electrodes play an analogous role in electro - chemistry. The prospect of selectively ionizing a... acetaldehyde and butyraldehyde have been studied at the KrF and ArF laser wavelengths. Their ionization potentials are 10.2 and 9.8 eV, respectively

Hybrid active vibration control of rotorbearing systems using piezoelectric actuators

NASA Technical Reports Server (NTRS)

Palazzolo, A. B.; Jagannathan, S.; Kascak, A. F.; Montague, G. T.; Kiraly, L. J.

1993-01-01

The vibrations of a flexible rotor are controlled using piezoelectric actuators. The controller includes active analog components and a hybrid interface with a digital computer. The computer utilizes a grid search algorithm to select feedback gains that minimize a vibration norm at a specific operating speed. These gains are then downloaded as active stillnesses and dampings with a linear fit throughout the operating speed range to obtain a very effective vibration control.

Vibration Analysis of Beam and Block Precast Slab System due to Human Vibrations

NASA Astrophysics Data System (ADS)

Chik, T. N. T.; Kamil, M. R. H.; Yusoff, N. A.

2018-04-01

Beam and block precast slabs system are very efficient which generally give maximum structural performance where their voids based on the design of the unit soffit block allow a significant reduction of the whole slab self-weight. Initially for some combinations of components or the joint connection of the structural slab, this structural system may be susceptible to excessive vibrations that could effects the performance and also serviceability. Dynamic forces are excited from people walking and jumping which produced vibrations to the slab system in the buildings. Few studies concluded that human induced vibration on precast slabs system may be harmful to structural performance and mitigate the human comfort level. This study will investigate the vibration analysis of beam and block precast slab by using finite element method at the school building. Human activities which are excited from jumping and walking will induce the vibrations signal to the building. Laser Doppler Vibrometer (LDV) was used to measure the dynamic responses of slab towards the vibration sources. Five different points were assigned specifically where each of location will determine the behaviour of the entire slabs. The finite element analyses were developed in ABAQUS software and the data was further processed in MATLAB ModalV to assess the vibration criteria. The results indicated that the beam and block precast systems adequate enough to the vibration serviceability and human comfort criteria. The overall vibration level obtained was fell under VC-E curve which it is generally under the maximum permissible level of vibrations. The vibration level on the slab is acceptable within the limit that have been used by Gordon.

Ride quality criteria. [transportation system interior and passenger response to environment

NASA Technical Reports Server (NTRS)

Stephens, D. G.

1977-01-01

Ride quality refers to the interior or passenger environment of a transportation system as well as the passenger response to the environment. Ride quality factors are illustrated with the aid of a diagram presenting inputs to vehicle, the vehicle transfer function, the ride environment, the passenger response function, and the passenger ride response. The reported investigation considers the ride environment as measured on a variety of air and surface vehicles, the passenger response to the environment as determined from laboratory and field surveys, and criteria/standards for vibration, noise, and combined stimuli. Attention is given to the vertical vibration characteristics in cruise for aircraft and automobile, the aircraft vibration levels for various operating regimes, comparative noise levels during cruise, the discomfort level for a 9 Hz sinusoidal vibration, equal discomfort contours for vertical vibration, subjective response to noise in a speech situation, and noise and vibration levels for constant discomfort contours.

Effect of vibration duration on human discomfort. [passenger comfort and random vibration

NASA Technical Reports Server (NTRS)

Clevenson, S. A.; Dempsey, T. K.; Leatherwood, J. D.

1978-01-01

The duration effects of random vertical vibration on passenger discomfort were studied in a simulated section of an aircraft cabin configured to seat six persons in tourist-class style. Variables of the study included time of exposure (0.25 min to 60 min) and the rms amplitude of vibration (0.025g to 0.100g). The vibrations had a white noise spectrum with a bandwidth of 10 Hz centered at 5 Hz. Data indicate that the discomfort threshold occurred at an rms vertical acceleration level of 0.027g for all durations of vibration. However, for acceleration levels that exceeded the discomfort threshold, a systematic decrease in discomfort occurred as a function of increasing duration of vibration. For the range of accelerations used, the magnitude of the discomfort decrement was shown to be independent of acceleration level. The results suggest that discomfort from vertical vibration applied in the frequency range at which humans are most sensitive decreases with longer exposure, which is the opposite of the recommendation of the International Standard ISO 2631-1974 (E) Guide for the Evaluation of Human Exposure to Whole-Body Vibration.

Effect of situational, attitudinal and demographic factors on railway vibration annoyance in residential areas.

PubMed

Peris, Eulalia; Woodcock, James; Sica, Gennaro; Sharp, Calum; Moorhouse, Andrew T; Waddington, David C

2014-01-01

Railway induced vibration is an important source of annoyance among residents living in the vicinity of railways. Annoyance increases with vibration magnitude. However, these correlations between the degree of annoyance and vibration exposure are weak. This suggests that railway vibration induced annoyance is governed by more than just vibration level and therefore other factors may provide information to understand the wide variation in annoyance reactions. Factors coming into play when considering an exposure-response relationship between level of railway vibration and annoyance are presented. The factors investigated were: attitudinal, situational and demographic factors. This was achieved using data from field studies comprised of face-to-face interviews and internal vibration measurements (N = 755). It was found that annoyance scores were strongly influenced by two attitudinal factors: Concern of property damage and expectations about future levels of vibration. Type of residential area and age of the respondent were found to have an important effect on annoyance whereas visibility of the railway and time spent at home showed a significant but small influence. These results indicate that future railway vibration policies and regulations focusing on community impact need to consider additional factors for an optimal assessment of railway effects on residential environments.

Dynamic Analysis of an Office Building due to Vibration from Road Construction Activities

NASA Astrophysics Data System (ADS)

Chik, T. N. T.; Kamil, M. R. H.; Yusoff, N. A.; Ibrahim, M. H. W.

2018-04-01

Construction activities are widely known as one of the predominant sources of man-made vibrations that able to create nuisance towards any adjacent building, and this includes the road construction operations. Few studies conclude the construction-induced vibration may be harmful directly and indirectly towards the neighbouring building. This lead to the awareness of study the building vibration response of concrete masonry load bearing system and its vibrational performance towards the road construction activities. This study will simulate multi-storey office building of Sekolah Menengah Kebangsaan (SMK) Bandar Enstek at Negeri Sembilan by using finite element vibration analyses. The excitation of transient loads from ground borne vibrations which triggered by the road construction activities are modelled into the building. The vibration response was recorded during in-situ ambient vibration test by using Laser Doppler Vibrometer (LDV), which specifically performed on four different locations. The finite element simulation process was developed in the commercial FEA software ABAQUS. Then, the experimental data was processed and evaluated in MATLAB ModalV to assess the vibration criteria of the floor in building. As a result, the vibration level of floor in building is fall under VC-E curve which was under the maximum permissible level for office building (VC-ISO). The vibration level on floor is acceptable within the limit that have been referred.

A Comparison of Molecular Vibrational Theory to Huckel Molecular Orbital Theory.

ERIC Educational Resources Information Center

Keeports, David

1986-01-01

Compares the similar mathematical problems of molecular vibrational calculations (at any intermediate level of sophistication) and molecular orbital calculations (at the Huckel level). Discusses how the generalizations of Huckel treatment of molecular orbitals apply to vibrational theory. (TW)

Granular Media-Based Tunable Passive Vibration Suppressor

NASA Technical Reports Server (NTRS)

Dillon, Robert P.; Davis, Gregory L.; Shapiro, Andrew A.; Borgonia, John Paul C.; Kahn, Daniel L.; Boechler, Nicholas; Boechler,, Chiara

2013-01-01

and vibration suppression device is composed of statically compressed chains of spherical particles. The device superimposes a combination of dissipative damping and dispersive effects. The dissipative damping resulting from the elastic wave attenuation properties of the bulk material selected for the granular media is independent of particle geometry and periodicity, and can be accordingly designed based on the dissipative (or viscoelastic) properties of the material. For instance, a viscoelastic polymer might be selected where broadband damping is desired. In contrast, the dispersive effects result from the periodic arrangement and geometry of particles composing a linear granular chain. A uniform (monatomic) chain of statically compressed spherical particles will have a low-pass filter effect, with a cutoff frequency tunable as a function of particle mass, elastic modulus, Poisson fs ratio, radius, and static compression. Elastic waves with frequency content above this cutoff frequency will exhibit an exponential decay in amplitude as a function of propagation distance. System design targeting a specific application is conducted using a combination of theoretical, computational, and experimental techniques to appropriately select the particle radii, material (and thus elastic modulus and Poisson fs ratio), and static compression to satisfy estimated requirements derived for shock and/or vibration protection needs under particular operational conditions. The selection of a chain of polymer spheres with an elastic modulus .3 provided the appropriate dispersive filtering effect for that exercise; however, different operational scenarios may require the use of other polymers, metals, ceramics, or a combination thereof, configured as an array of spherical particles. The device is a linear array of spherical particles compressed in a container with a mechanism for attachment to the shock and/or vibration source, and a mechanism for attachment to the article requiring isolation (Figure 1). This configuration is referred to as a single-axis vibration suppressor. This invention also includes further designs for the integration of the single-axis vibration suppressor into a six-degree-of-freedom hexapod "Stewart"mounting configuration (Figure 2). By integrating each singleaxis vibration suppressor into a hexapod formation, a payload will be protected in all six degrees of freedom from shock and/or vibration. Additionally, to further enable the application of this device to multiple operational scenarios, particularly in the case of high loads, the vibration suppressor devices can be used in parallel in any array configuration.

Concorde noise-induced building vibrations, John F. Kennedy International Airport

NASA Technical Reports Server (NTRS)

Mayes, W. H.; Deloach, R.; Stephens, D. G.; Cawthorn, J. M.; Holmes, H. K.; Lewis, R. B.; Holliday, B. G.; Miller, W. T.; Ward, D. W.

1978-01-01

The outdoor/indoor noise levels and associated vibration levels resulting from aircraft and nonaircraft events were recorded at eight homesites and a school. In addition, limited subjective tests were conducted to examine the human detection/annoyance thresholds for building vibration and rattle caused by aircraft noise. Presented herein are the majority of the window and wall vibration data recorded during Concorde and subsonic aircraft overflights.

Quantification of the effects of audible rattle and source type on the human response to environmental vibration.

PubMed

Woodcock, J; Sica, G; Peris, E; Sharp, C; Moorhouse, A T; Waddington, D C

2016-03-01

The present research quantifies the influence of source type and the presence of audible vibration-induced rattle on annoyance caused by vibration in residential environments. The sources of vibration considered are railway and the construction of a light rail system. Data were measured in the United Kingdom using a socio-vibration survey (N = 1281). These data are analyzed using ordinal logit models to produce exposure-response relationships describing community annoyance as a function of vibration exposure. The influence of source type and the presence of audible vibration-induced rattle on annoyance are investigated using dummy variable analysis, and quantified using odds-ratios and community tolerance levels. It is concluded that the sample population is more likely to express higher levels of annoyance if the vibration source is construction compared to railway, and if vibration-induced rattle is audible.

Femtochemistry in the electronic ground state: Dynamic Stark control of vibrational dynamics

NASA Astrophysics Data System (ADS)

Shu, Chuan-Cun; Thomas, Esben F.; Henriksen, Niels E.

2017-09-01

We study the interplay of vibrational and rotational excitation in a diatomic molecule due to the non-resonant dynamic Stark effect. With a fixed peak intensity, optimal Gaussian pulse durations for maximizing vibrational or rotational transitions are obtained analytically and confirmed numerically for the H2 and Cl2 molecules. In general, pulse trains or more advanced pulse shaping techniques are required in order to obtain significant vibrational excitation. To that end, we demonstrate that a high degree of selectivity between vibrational and rotational excitation is possible with a suitably phase-modulated Gaussian pulse.

Vibrational pumping and heating under SERS conditions: fact or myth?

PubMed

Le Ru, E C; Etchegoin, P G

2006-01-01

We address in this paper the long debated issue of the possibility of vibrational pumping under Surface Enhanced Raman Scattering (SERS) conditions, both theoretically and experimentally. We revisit with simple theoretical models the mechanisms of vibrational pumping and its relation to heating. This presentation provides a clear classification of the various regimes of heating/pumping, from simple global laser heating to selective pumping of a single vibrational mode. We also propose the possibility of extreme pumping driven by stimulated phonon emission, and we introduce and apply a new experimental technique to study these effects in SERS. Our method relies on correlations between Raman peak parameters, and cross-correlation for two Raman peaks. We find strong evidence for local and dynamical heating, but no convincing evidence for selective pumping under our specific experimental SERS conditions.

Bond-selective photoacoustic imaging by converting molecular vibration into acoustic waves

PubMed Central

Hui, Jie; Li, Rui; Phillips, Evan H.; Goergen, Craig J.; Sturek, Michael; Cheng, Ji-Xin

2016-01-01

The quantized vibration of chemical bonds provides a way of detecting specific molecules in a complex tissue environment. Unlike pure optical methods, for which imaging depth is limited to a few hundred micrometers by significant optical scattering, photoacoustic detection of vibrational absorption breaks through the optical diffusion limit by taking advantage of diffused photons and weak acoustic scattering. Key features of this method include both high scalability of imaging depth from a few millimeters to a few centimeters and chemical bond selectivity as a novel contrast mechanism for photoacoustic imaging. Its biomedical applications spans detection of white matter loss and regeneration, assessment of breast tumor margins, and diagnosis of vulnerable atherosclerotic plaques. This review provides an overview of the recent advances made in vibration-based photoacoustic imaging and various biomedical applications enabled by this new technology. PMID:27069873

[Low magnitude whole-body vibration and postmenopausal osteoporosis].

PubMed

Li, Huiming; Li, Liang

2018-04-01

Postmenopausal osteoporosis is a type of osteoporosis with high bone transformation rate, caused by a decrease of estrogen in the body, which is a systemic bone disease characterized by decreased bone mass and increased risk of fracture. In recent years, as a kind of non-pharmacologic treatment of osteoporosis, defined by whole-body vibration less than 1 g ( g = 9.81 m/s 2 ), low magnitude whole-body vibration is widely concerned, mainly because of its small side effects, simple operation and relative safety. Studies have shown that low magnitude whole-body vibration can improve bone strength, bone volume and bone density. But a lot of research found that, the therapeutic effects of low magnitude whole-body vibration are different depending on ages and hormone levels of subjects for animal models or human patients. There has been no definite vibration therapy can be applied to each subject so far. Studies of whole-body and cellular level suggest that low magnitude whole-body vibration stimulation is likely to be associated with changes of hormone levels and directed differentiation of stem cells. Based on the analysis of related literature in recent years, this paper made a review from vibration parameters, vibration effects and the mechanisms, to provide scientific basis and clinical guidance for the treatment of postmenopausal osteoporosis with low magnitude whole-body vibration.

Full-Dimensional Quantum Calculations of Vibrational Levels of NH4(+) and Isotopomers on An Accurate Ab Initio Potential Energy Surface.

PubMed

Yu, Hua-Gen; Han, Huixian; Guo, Hua

2016-04-14

Vibrational energy levels of the ammonium cation (NH4(+)) and its deuterated isotopomers are calculated using a numerically exact kinetic energy operator on a recently developed nine-dimensional permutation invariant semiglobal potential energy surface fitted to a large number of high-level ab initio points. Like CH4, the vibrational levels of NH4(+) and ND4(+) exhibit a polyad structure, characterized by a collective quantum number P = 2(v1 + v3) + v2 + v4. The low-lying vibrational levels of all isotopomers are assigned and the agreement with available experimental data is better than 1 cm(-1).

Study of T53 engine vibration

NASA Technical Reports Server (NTRS)

Walter, T. J.

1978-01-01

Vibration characteristics for overhauled T53 engines, including rejection rate, principal sources of vibration, and normal procedures taken by the overhaul center to reduce engine vibration are summarized. Analytical and experimental data were compared to determine the engine's dynamic response to unbalance forces with results showing that the engine operates through bending critical speeds. Present rigid rotor balancing techniques are incapable of compensating for the flexible rotor unbalance. A comparison of typical test cell and aircraft vibration levels disclosed significant differences in the engine's dynamic response. A probable spline shift phenomenon was uncovered and investigated. Action items to control costs and reduce vibration levels were identified from analytical and experimental studies.

Whole-body vibration exposure of haul truck drivers at a surface coal mine.

PubMed

Wolfgang, Rebecca; Burgess-Limerick, Robin

2014-11-01

Haul truck drivers at surface mines are exposed to whole-body vibration for extended periods. Thirty-two whole-body vibration measurements were gathered from haul trucks under a range of normal operating conditions. Measurements taken from 30 of the 32 trucks fell within the health guidance caution zone defined by ISO2631-1 for an 8 h daily exposure suggesting, according to ISO2631-1, that "caution with respect to potential health risks is indicated". Maintained roadways were associated with substantially lower vibration amplitudes. Larger trucks were associated with lower vibration levels than small trucks. The descriptive nature of the research, and small sample size, prevents any strong conclusion regarding causal links. Further investigation of the variables associated with elevated vibration levels is justified. The operators of mining equipment such as haul trucks are exposed to whole-body vibration amplitudes which have potential to lead to long term health effects. Systematic whole-body vibration measurements taken at frequent intervals are required to provide an understanding of the causes of elevated vibration levels and hence determine appropriate control measures. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: AMSU-A1 EOS Instrument, (S/N 202) Qualification Level Vibration Tests of August/September 1998, (S/O 565632, OC-417) Plus Addendum A

NASA Technical Reports Server (NTRS)

Heffer, R.

1998-01-01

The purpose of this report is to present a qualification level vibration testing performed on the S/N 202, EOS AMSU-A1 Instrument was vibration tested to qualification levels per the Ref. 1 shop order. The instrument withstood the 8 g sine sweep test, the 7.5 Grms random vibration test, and the 18.75 g sine burst test in each of the three orthogonal axes. Some loss of transmissibility, however, is seen in the lower reflector after Z-axis random vibration. The test sequence was not without incidence. Failure of Channel 7 in the Limited Performance Test (LPT) performed after completion of the 1 st (X-axis) axis vibration sequence, required replacement of the DRO and subsequent re-testing of the instrument. The post-vibration comprehensive performance test (CPT) was successfully run after completion of the three axes of vibration with the replacement component installed in the instrument. Passing the CPT signified the successful completion of the S/N 202 A1 qualification vibration testing.

Lightweight Vehicle and Driver’s Whole-Body Models for Vibration Analysis

NASA Astrophysics Data System (ADS)

MdSah, Jamali; Taha, Zahari; Azwan Ismail, Khairul

2018-03-01

Vehicle vibration is a main factor for driving fatigue, discomfort and health problems. The ability to simulate the vibration characteristics in the vehicle and its effects on driver’s whole-body vibration will give significant advantages to designers especially on the vehicle development time and cost. However, it is difficult to achieve optimal condition of ride comfort and handling when using passive suspension system. This paper presents mathematical equations that can be used to describe the vibration characteristics of a lightweight electric vehicle that had been developed. The vehicle’s model was combined with the lumped-parameter model of driver to determine the whole-body vibration level when the vehicle is passing over a road hump using Matlab Simulink. The models were simulated at a constant speed and the results were compared with the experimental data. The simulated vibration level at the vehicle floor and seat were almost similar to the experimental vibration results. The suspension systems that are being used for the solar vehicle are able to reduce the vibration level due to the road hump. The models can be used to simulate and choose the optimal parameters for the suspensions.

Electronics Reliability Fracture Mechanics, Volume 2. Fracture Mechanics

DTIC Science & Technology

1992-05-01

alloy or strength level. Aluminum alloy 2024 - T351 was selected as being representative of the aluminum wire, and the fatigue ...to bracket the bond wire fatigue tests. 3-41 Also shown for comparison are two curves, which are the crack growth rates for 2024 aluminum alloy (Ref...is very similar to that for 2024 aluminum alloy . 3.2.6 Discussion of Loop Vibration Fatigue Testing Results This experimental and

Military display performance parameters

NASA Astrophysics Data System (ADS)

Desjardins, Daniel D.; Meyer, Frederick

2012-06-01

The military display market is analyzed in terms of four of its segments: avionics, vetronics, dismounted soldier, and command and control. Requirements are summarized for a number of technology-driving parameters, to include luminance, night vision imaging system compatibility, gray levels, resolution, dimming range, viewing angle, video capability, altitude, temperature, shock and vibration, etc., for direct-view and virtual-view displays in cockpits and crew stations. Technical specifications are discussed for selected programs.

Rotationally mediated selective adsorption as a probe of isotropic and anisotropic molecule. Surface interaction potentials: HD(J)/Ag(111)

NASA Astrophysics Data System (ADS)

Uy, C. F.; Hogg, C. S.; Cowin, J. P.; Whaley, K. B.; Light, J. C.; Sibener, S. J.

1982-08-01

Rotationally mediated selective adsorption scattering resonances are used to make an experimental and theoretical study of the laterally averaged interaction potential between HD and a weakly corrugated system, Ag(111). The experimentally observed resonances determine the vibrational levels of the HD/Ag(111) physisorption potential as a function of bound rotational state. These vibrational levels show J-dependent shifts due to the orientational anisotropy of the potential. Exact quantum scattering calculations using a full laterally averaged potential of the form V sub o(z,0) = v sub o (z) (1 + beta P sub 2 (cos theta)) have been carried out to obtain rotationally inelastic transition probabilities. Experimental and theoretical resonance energies are compared for two forms of v sub o(z), a Morse and a variable exponent potential, as a function of Beta, and are found to be very close to the first order perturbed energies of a free rotor in bound states of v sub o(z). Both potential forms give equally good fits to the data, yielding an optimum value of the asymmetry parameter, Beta approx. -0.05. The determination of Beta is relatively insensitive to small changes in the v sub o(z) well depth.

Experimental investigation of railway train-induced vibrations of surrounding ground and a nearby multi-story building

NASA Astrophysics Data System (ADS)

Xia, He; Chen, Jianguo; Wei, Pengbo; Xia, Chaoyi; de Roeck, G.; Degrande, G.

2009-03-01

In this paper, a field experiment was carried out to study train-induced environmental vibrations. During the field experiment, velocity responses were measured at different locations of a six-story masonry structure near the Beijing-Guangzhou Railway and along a small road adjacent to the building. The results show that the velocity response levels of the environmental ground and the building floors increase with train speed, and attenuate with the distance to the railway track. Heavier freight trains induce greater vibrations than lighter passenger trains. In the multi-story building, the lateral velocity levels increase monotonically with floor elevation, while the vertical ones increase with floor elevation in a fluctuating manner. The indoor floor vibrations are much lower than the outdoor ground vibrations. The lateral vibration of the building along the direction of weak structural stiffness is greater than along the direction with stronger stiffness. A larger room produces greater floor vibrations than the staircase at the same elevation, and the vibration at the center of a room is greater than at its corner. The vibrations of the building were compared with the Federal Transportation Railroad Administration (FTA) criteria for acceptable ground-borne vibrations expressed in terms of rms velocity levels in decibels. The results show that the train-induced building vibrations are serious, and some exceed the allowance given in relevant criterion.

The discomfort produced by noise and whole-body vertical vibration presented separately and in combination.

PubMed

Huang, Yu; Griffin, Michael J

2014-01-01

This study investigated the prediction of the discomfort caused by simultaneous noise and vibration from the discomfort caused by noise and the discomfort caused by vibration when they are presented separately. A total of 24 subjects used absolute magnitude estimation to report their discomfort caused by seven levels of noise (70-88 dBA SEL), 7 magnitudes of vibration (0.146-2.318 ms(- 1.75)) and all 49 possible combinations of these noise and vibration stimuli. Vibration did not significantly influence judgements of noise discomfort, but noise reduced vibration discomfort by an amount that increased with increasing noise level, consistent with a 'masking effect' of noise on judgements of vibration discomfort. A multiple linear regression model or a root-sums-of-squares model predicted the discomfort caused by combined noise and vibration, but the root-sums-of-squares model is more convenient and provided a more accurate prediction of the discomfort produced by combined noise and vibration.

Vibration and Operational Characteristics of a Composite-Steel (Hybrid) Gear

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.; LaBerge, Kelsen E.; DeLuca, Samuel; Pelagalli, Ryan

2014-01-01

Hybrid gears have been tested consisting of metallic gear teeth and shafting connected by composite web. Both free vibration and dynamic operation tests were completed at the NASA Glenn Spur Gear Fatigue Test Facility, comparing these hybrid gears to their steel counterparts. The free vibration tests indicated that the natural frequency of the hybrid gear was approximately 800 Hz lower than the steel test gear. The dynamic vibration tests were conducted at five different rotational speeds and three levels of torque in a four square test configuration. The hybrid gears were tested both as fabricated (machined, composite layup, then composite cure) and after regrinding the gear teeth to the required aerospace tolerance. The dynamic vibration tests indicated that the level of vibration for either type of gearing was sensitive to the level of load and rotational speed.

Comparative Vibration Levels Perceived Among Species in a Laboratory Animal Facility

PubMed Central

Norton, John N; Kinard, Will L; Reynolds, Randall P

2011-01-01

The current study was performed to determine the vibration levels that were generated in cages on a ventilated rack by common construction equipment in frequency ranges likely to be perceived by humans, rats, and mice. Vibration generated by the ventilated rack blower caused small but significant increases in some of the abdominal, thoracic, and head resonance frequency ranges (RFR) and sensitivity frequency ranges (SFR) in which each species is most likely to be affected by and perceive vibration, respectively. Vibration caused by various items of construction equipment at 3 ft from the cage were evaluated relative to the RFR and SFR of humans, rats, and mice in 3 anatomic locations. In addition, the vibration levels in the RFR and SFR that resulted from the use of a large jackhammer and were measured at various locations and distances in the facility and evaluated in terms of humans, rats, and mice in 3 anatomic locations. Taken together, the data indicate that a given vibration source generates vibration in frequency ranges that are more likely to affect rats and mice as compared with humans. PMID:22330711

Turbine gas temperature measurement and control system

NASA Technical Reports Server (NTRS)

Webb, W. L.

1973-01-01

A fluidic Turbine Inlet Gas Temperature (TIGIT) Measurement and Control System was developed for use on a Pratt and Whitney Aircraft J58 engine. Based on engine operating requirements, criteria for high temperature materials selection, system design, and system performance were established. To minimize development and operational risk, the TIGT control system was designed to interface with an existing Exhaust Gas Temperature (EGT) Trim System and thereby modulate steady-state fuel flow to maintain a desired TIGT level. Extensive component and system testing was conducted including heated (2300F) vibration tests for the fluidic sensor and gas sampling probe, temperature and vibration tests on the system electronics, burner rig testing of the TIGT measurement system, and in excess of 100 hours of system testing on a J58 engine. (Modified author abstract)

The Anti-Resonance Criterion in Selecting Pick Systems for Fully Operational Cutting Machinery Used in Mining

NASA Astrophysics Data System (ADS)

Cheluszka, Piotr

2017-12-01

This article discusses the issue of selecting a pick system for cutting mining machinery, concerning the reduction of vibrations in the cutting system, particularly in a load-carrying structure at work. Numerical analysis was performed on a telescopic roadheader boom equipped with transverse heads. A frequency range of the boom's free vibrations with a set structure and dynamic properties were determined based on a dynamic model. The main components excited by boom vibrations, generated through the process of cutting rock, were identified. This was closely associated with the stereometry of the cutting heads. The impact on the pick system (the number of picks and their arrangement along the side of the cutting head) was determined by the intensity of the external boom load elements, especially in resonance zones. In terms of the anti-resonance criterion, an advantageous system of cutting head picks was determined as a result of the analysis undertaken. The correct selection of the pick system was ascertained based on a computer simulation of the dynamic loads and vibrations of a roadheader telescopic boom.

Actuator placement for active sound and vibration control of cylinders

NASA Technical Reports Server (NTRS)

Kincaid, Rex K.

1995-01-01

Active structural acoustic control is a method in which the control inputs (used to reduce interior noise) are applied directly to a vibrating structural acoustic system. The control concept modeled in this work is the application of in-plane force inputs to piezoceramic patches bonded to the wall of a vibrating cylinder. The cylinder is excited by an exterior noise source -- an acoustic monopole -- located near the outside of the cylinder wall. The goal is to determine the force inputs and sites for the piezoelectric actuators so that (1) the interior noise is effectively damped; (2) the level of vibration of the cylinder shell is not increased; and (3) the power requirements needed to drive the actuators are not excessive. We studied external monopole excitations at two frequencies. A cylinder resonance of 100 Hz, where the interior acoustic field is driven in multiple, off-resonance cylinder cavity modes, and a cylinder resonance of 200 Hz are characterized by both near and off-resonance cylinder vibration modes which couple effectively with a single, dominant, low-order acoustic cavity mode at resonance. Previous work has focused almost exclusively on meeting objective (1) and solving a complex least-squares problem to arrive at an optimal force vector for a given set of actuator sites. In addition, it has been noted that when the cavity mode couples with cylinder vibration modes (our 200 Hz case) control spillover may occur in higher order cylinder shell vibrational modes. How to determine the best set of actuator sites to meet objectives (1)-(3) is the main contribution of our research effort. The selection of the best set of actuator sites from a set of potential sites is done via two metaheuristics -- simulated annealing and tabu search. Each of these metaheuristics partitions the set of potential actuator sites into two disjoint sets: those that are selected to control the noise (on) and those that are not (off). Next, each metaheuristic attempts to improve this initial solution by calculating the change in the objective value when one selected actuator site is turned off and one actuator site that previously was not selected is turned on. All such pairwise exchanges are performed and the exchange that improves the objective the most is made. Eventually the search is unable to improve the objective value and a local optimum (with respect to pairwise exchanges) is reached. Both simulated annealing and tabu search provide mechanisms to escape local optima and allow the search to continue until (hopefully) a global optimum is found. Our experiments with the 100 Hz and 200 Hz cases confirm that both metaheuristics are able to uncover better solutions than those selected based upon engineering judgement alone. In addition, the high quality solutions generated by these metaheuristics, when minimizing interior noise, do not further excite the cylinder shell. Thus, we are able to meet objective (2) without imposing an additional constraint or forming a multiobjective performance measure. An additional observation is that in many cases the amplitude and phase values for several chosen actuator sites were nearly identical. This natural grouping means that fewer control channels are needed and the resulting control system is simpler. Currently no power requirements have been set, so objective (3) cannot be addressed. A set of experiments is planned with a laboratory test article (a cylinder). For these experiments the transfer matrices will be generated experimentally. It is hoped that the predicted performance of the best actuator sites found by our metaheuristics will correlate well with the measured performance.

Selection of site specific vibration equation by using analytic hierarchy process in a quarry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalayci, Ulku, E-mail: ukalayci@istanbul.edu.tr; Ozer, Umit, E-mail: uozer@istanbul.edu.tr

This paper presents a new approach for the selection of the most accurate SSVA (Site Specific Vibration Attenuation) equation for blasting processes in a quarry located near settlements in Istanbul, Turkey. In this context, the SSVA equations obtained from the same study area in the literature were considered in terms of distance between the shot points and buildings and the amount of explosive charge. In this purpose, 11 different SSVA equations obtained from the study area in the past 12 years, forecasting capabilities according to designated new conditions, using 102 vibration records as test data obtained from the study areamore » was investigated. In this study, AHP (Analytic Hierarchy Process) was selected as an analysis method in order to determine the most accurate equation among 11 SSAV equations, and the parameters such as year, distance, charge, and r{sup 2} of the equations were used as criteria for AHP. Finally, the most appropriate equation was selected among the existing ones, and the process of selecting according to different target criteria was presented. Furthermore, it was noted that the forecasting results of the selected equation is more accurate than that formed using the test results. - Highlights: • The optimum Site Specific Vibration Attenuation equation for blasting in a quarry located near settlements was determined. • It is indicated that SSVA equations changing over the years don’t give always accurate estimates at changing conditions. • Selection of the blast induced SSVA equation was made using AHP. • Equation selection method was highlighted based on parameters such as charge, distance, and quarry geometry changes (year).« less

A second-order multi-reference perturbation method for molecular vibrations

NASA Astrophysics Data System (ADS)

Mizukami, Wataru; Tew, David P.

2013-11-01

We present a general multi-reference framework for treating strong correlation in vibrational structure theory, which we denote the vibrational active space self-consistent field (VASSCF) approach. Active configurations can be selected according to excitation level or the degrees of freedom involved, or both. We introduce a novel state-specific second-order multi-configurational perturbation correction that accounts for the remaining weak correlation between the vibrational modes. The resulting VASPT2 method is capable of accurately and efficiently treating strong correlation in the form of large anharmonic couplings, at the same time as correctly resolving resonances between states. These methods have been implemented in our new dynamics package DYNAMOL, which can currently treat up to four-body Hamiltonian coupling terms. We present a pilot application of the VASPT2 method to the trans isomer of formic acid. We have constructed a new analytic potential that reproduces frozen core CCSD(T)(F12*)/cc-pVDZ-F12 energies to within 0.25% RMSD over the energy range 0-15 000 cm-1. The computed VASPT2 fundamental transition energies are accurate to within 9 cm-1 RMSD from experimental values, which is close to the accuracy one can expect from a CCSD(T) potential energy surface.

A cross sectional study on hand-arm vibration syndrome among a group of tree fellers in a tropical environment.

PubMed

Su, Anselm Ting; Maeda, Setsuo; Fukumoto, Jin; Miyai, Nobuyuki; Isahak, Marzuki; Yoshioka, Atsushi; Nakajima, Ryuichi; Bulgiba, Awang; Miyashita, Kazuhisa

2014-01-01

This study aimed to explore the clinical characteristics of hand arm vibration syndrome (HAVS) in a group of tree fellers in a tropical environment. We examined all tree fellers and selected control subjects in a logging camp of central Sarawak for vibration exposure and presence of HAVS symptoms utilizing vibrotactile perception threshold test (VPT) and cold water provocation test (CWP). None of the subjects reported white finger. The tree fellers reported significantly higher prevalence of finger coldness as compared to the control subjects (OR=10.32, 95%CI=1.21-87.94). A lower finger skin temperature, longer fingernail capillary return time and higher VPT were observed among the tree fellers as compared to the control subjects in all fingers (effect size >0.5). The VPT following CWP of the tree fellers was significantly higher (repeated measures ANOVA p=0.002, partial η(2)=0.196) than the control subject. The A (8) level was associated with finger tingling, numbness and dullness (effect size=0.983) and finger coldness (effect size=0.524) among the tree fellers. Finger coldness and finger tingling, numbness and dullness are important symptoms for HAVS in tropical environment that may indicate vascular and neurological damage due to hand-transmitted vibration exposure.

Low back and neck pain in locomotive engineers exposed to whole-body vibration.

PubMed

McBride, David; Paulin, Sara; Herbison, G Peter; Waite, David; Bagheri, Nasser

2014-01-01

The objective of this study was to determine the prevalence and excess risk of low back pain and neck pain in locomotive engineers, and to investigate the relationship of both with whole-body vibration exposure. A cross-sectional survey comparing locomotive engineers with other rail worker referents was conducted. Current vibration levels were measured, cumulative exposures calculated for engineers and referents, and low back and neck pain assessed by a self-completed questionnaire. Median vibration exposure in the z- (vertical) axis was 0.62 m/s(2). Engineers experienced more frequent low back and neck pain, odds ratios (ORs) of 1.77 (95% confidence interval [CI]: 1.19-2.64) and 1.92 (95% CI: 1.22-3.02), respectively. The authors conclude that vibration close to the "action levels" of published standards contribute to low back and neck pain. Vibration levels need to be assessed conservatively and control measures introduced.

Sound radiation from randomly vibrating beams of finite circular cross section

NASA Technical Reports Server (NTRS)

Sutterlin, M. W.; Pierce, A. D.

1976-01-01

The radiation of sound from vibrating cylindrical beams is analyzed based on the frequency of the beam vibrations and the physical characteristics of the beam and its surroundings. A statistical analysis of random beam vibrations allows this result to be independent of the boundary conditions at the ends of the beam. The acoustic power radiated by the beam can be determined from a knowledge of the frequency band vibration data without a knowledge of the individual modal vibration amplitudes. A practical example of the usefulness of this technique is provided by the application of the theoretical calculations to the prediction of the octave band acoustic power output of the picking sticks of an automatic textile loom. Calculations are made of the expected octave band sound pressure levels based on measured acceleration data. These theoretical levels are subsequently compared with actual sound pressure level measurements of loom noise.

Molecular vibrational trapping revisited: a case study with D2+

PubMed Central

Badankó, Péter; Halász, Gábor J.; Vibók, Ágnes

2016-01-01

The present theoretical study is concerned with the vibrational trapping or bond hardening, which is a well-known phenomenon predicted by a dressed state representation of small molecules like and in an intense laser field. This phenomenon is associated with a condition where the energy of the light induced, vibrational level coincides with one of the vibrational levels on the field-free potential curve, which at the same time maximizes the wave function overlap between these two levels. One-dimensional numerical simulations were performed to investigate this phenomenon in a more quantitative way than has been done previously by calculating the photodissociation probability of for a wide range of photon energy. The obtained results undoubtedly show that the nodal structure of the field-free vibrational wave functions plays a decisive role in the vibrational trapping, in addition to the current understanding of this phenomenon. PMID:27550642

The feasibility of using methylene blue sensitized polyvinylalcohol film as a linear polarizer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jyothilakshmi, K.; Anju, K. S.; Arathy, K.

2014-01-28

Linear light polarizing films selectively transmit radiations vibrating along an electromagnetic radiation vector and selectively absorb radiations vibrating along a second electromagnetic radiation vector. It happens according to the anisotropy of the film . In the present study the polarization effects of methylene blue sensitized polyvinyl alcohol is investigated. The polarization effects on the dye concentration, heating and stretching of film also are evaluated.

Full-dimensional quantum calculations of vibrational levels of NH 4 + and isotopomers on an accurate ab initio potential energy surface

DOE PAGES

Hua -Gen Yu; Han, Huixian; Guo, Hua

2016-03-29

Vibrational energy levels of the ammonium cation (NH 4 +) and its deuterated isotopomers are calculated using a numerically exact kinetic energy operator on a recently developed nine-dimensional permutation invariant semiglobal potential energy surface fitted to a large number of high-level ab initio points. Like CH4, the vibrational levels of NH 4 + and ND 4 + exhibit a polyad structure, characterized by a collective quantum number P = 2(v 1 + v 3) + v 2 + v 4. As a result, the low-lying vibrational levels of all isotopomers are assigned and the agreement with available experimental data ismore » better than 1 cm –1.« less

Development of rotorcraft interior noise control concepts. Phase 2: Full scale testing, revision 1

NASA Technical Reports Server (NTRS)

Yoerkie, C. A.; Gintoli, P. J.; Moore, J. A.

1986-01-01

The phase 2 effort consisted of a series of ground and flight test measurements to obtain data for validation of the Statistical Energy Analysis (SEA) model. Included in the gound tests were various transfer function measurements between vibratory and acoustic subsystems, vibration and acoustic decay rate measurements, and coherent source measurements. The bulk of these, the vibration transfer functions, were used for SEA model validation, while the others provided information for characterization of damping and reverberation time of the subsystems. The flight test program included measurements of cabin and cockpit sound pressure level, frame and panel vibration level, and vibration levels at the main transmission attachment locations. Comparisons between measured and predicted subsystem excitation levels from both ground and flight testing were evaluated. The ground test data show good correlation with predictions of vibration levels throughout the cabin overhead for all excitations. The flight test results also indicate excellent correlation of inflight sound pressure measurements to sound pressure levels predicted by the SEA model, where the average aircraft speech interference level is predicted within 0.2 dB.

Communication: Reactivity borrowing in the mode selective chemistry of H + CHD3 → H2 + CD3

NASA Astrophysics Data System (ADS)

Ellerbrock, Roman; Manthe, Uwe

2017-12-01

Quantum state-resolved reaction probabilities for the H + CHD3 → H2 + CD3 reaction are calculated by accurate full-dimensional quantum dynamics calculations using the multi-layer multi-configurational time-dependent Hartree approach and the quantum transition state concept. Reaction probabilities of various ro-vibrational states of the CHD3 reactant are investigated for vanishing total angular momentum. While the reactivity of the different vibrational states of CHD3 mostly follows intuitive patterns, an unusually large reaction probability is found for CHD3 molecules triply excited in the CD3 umbrella-bending vibration. This surprising reactivity can be explained by a Fermi resonance-type mixing of the single CH-stretch excited and the triple CD3 umbrella-bend excited vibrational states of CHD3. These findings show that resonant energy transfer can significantly affect the mode-selective chemistry of CHD3 and result in counter-intuitive reactivity patterns.

Quasi-simultaneous Measurements of Ionic Currents by Vibrating Probe and pH Distribution by Ion-selective Microelectrode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isaacs, H.S.; Lamaka, S.V.; Taryba, M.

2011-01-01

This work reports a new methodology to measure quasi-simultaneously the local electric fields and the distribution of specific ions in a solution via selective microelectrodes. The field produced by the net electric current was detected using the scanning vibrating electrode technique (SVET) with quasi-simultaneous measurements of pH with an ion-selective microelectrode (pH-SME). The measurements were performed in a validation cell providing a 48 ?m diameter Pt wire cross section as a source of electric current. A time lag between acquiring each current density and pH data-point was 1.5 s due to the response time of pH-SME. The quasi-simultaneous SVET-pH measurementsmore » that correlate electrochemical oxidation-reduction processes with acid-base chemical equilibria are reported for the first time. No cross-talk between the vibrating microelectrode and the ion-selective microelectrode could be detected under given experimental conditions.« less

Vibration Control of Deployable Astromast Boom: Preliminary Experiments

NASA Technical Reports Server (NTRS)

Swaminadham, M.; Hamilton, David A.

1994-01-01

This paper deals with the dynamic characterization of a flexible aerospace solar boom. The modeling issues and sine dwell vibration testing to determine natural frequencies and mode shapes of a continuous-longer on deployable ASTROMAST lattice boom are discussed. The details of the proof-of-concept piezoelectric active vibration experiments on a simple cantilever beam to control its vibrations are presented. The control parameters like voltage to the controller crystal and its location are investigated, to determine the effectiveness of control element to suppress selected resonant vibrations of the test specimen. Details of this experiment and plans for its future adaptation to the prototype structure are also discussed.

Effect of Bearings on Vibration in Rotating Machinery

NASA Astrophysics Data System (ADS)

Daniel, Rudrapati Victor; Amit Siddhappa, Savale; Bhushan Gajanan, Savale; Vipin Philip, S.; Paul, P. Sam

2017-08-01

In rotary machines vibration is an inherent phenomenon which has the tendency to affect required performance. Amongst the different parameters that affect vibration, selection of appropriate bearing is the most critical component. In this work the effect of different types of bearing on vibration in rotary machines is studied and the magnitude of vibration produced by use of different set of bearings under the same condition of loads and rotational speeds were investigated. Bearings considered in this work were ball bearing, tapered roller bearing, thrust bearing and shaft material considered is of mild steel. From experimental result, it was noted that tapered roller bearing gives the highest amplitude of vibration among all the three bearings whereas the ball bearing gives least amplitude under similar operating conditions.

Application of THz Vibrational Spectroscopy to Molecular Characterization and the Theoretical Fundamentals: An Illustration Using Saccharide Molecules.

PubMed

Zhang, Feng; Wang, Houng-Wei; Tominaga, Keisuke; Hayashi, Michitoshi; Hasunuma, Tomohisa; Kondo, Akihiko

2017-02-01

This work illustrates several theoretical fundamentals for the application of THz vibrational spectroscopy to molecular characterization in the solid state using two different types of saccharide systems as examples. Four subjects have been specifically addressed: (1) the qualitative differences in the molecular vibrational signatures monitored by THz and mid-IR vibrational spectroscopy; (2) the selection rules for THz vibrational spectroscopy as applied to crystalline and amorphous systems; (3) a normal mode simulation, using α-l-xylose as an example; and (4) a rigorous mode analysis to quantify the percentage contributions of the intermolecular and intramolecular vibrations to the normal mode of interest. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Human discomfort response to noise combined with vertical vibration

NASA Technical Reports Server (NTRS)

Leatherwood, J. D.

1979-01-01

An experimental investigation was conducted (1) to determine the effects of combined environmental noise and vertical vibration upon human subjective discomfort response, (2) to develop a model for the prediction of passenger discomfort response to the combined environment, and (3) to develop a set of noise-vibration curves for use as criteria in ride quality design. Subjects were exposed to parametric combinations of noise and vibrations through the use of a realistic laboratory simulator. Results indicated that accurate prediction of passenger ride comfort requires knowledge of both the level and frequency content of the noise and vibration components of a ride environment as well as knowledge of the interactive effects of combined noise and vibration. A design tool in the form of an empirical model of passenger discomfort response to combined noise and vertical vibration was developed and illustrated by several computational examples. Finally, a set of noise-vibration criteria curves were generated to illustrate the fundamental design trade-off possible between passenger discomfort and the noise-vibration levels that produce the discomfort.

Combined Effects of High-Speed Railway Noise and Ground Vibrations on Annoyance.

PubMed

Yokoshima, Shigenori; Morihara, Takashi; Sato, Tetsumi; Yano, Takashi

2017-07-27

The Shinkansen super-express railway system in Japan has greatly increased its capacity and has expanded nationwide. However, many inhabitants in areas along the railways have been disturbed by noise and ground vibration from the trains. Additionally, the Shinkansen railway emits a higher level of ground vibration than conventional railways at the same noise level. These findings imply that building vibrations affect living environments as significantly as the associated noise. Therefore, it is imperative to quantify the effects of noise and vibration exposures on each annoyance under simultaneous exposure. We performed a secondary analysis using individual datasets of exposure and community response associated with Shinkansen railway noise and vibration. The data consisted of six socio-acoustic surveys, which were conducted separately over the last 20 years in Japan. Applying a logistic regression analysis to the datasets, we confirmed the combined effects of vibration/noise exposure on noise/vibration annoyance. Moreover, we proposed a representative relationship between noise and vibration exposures, and the prevalence of each annoyance associated with the Shinkansen railway.

Rotationally inelastic scattering of ND3 with H2 as a probe of the intermolecular potential energy surface

NASA Astrophysics Data System (ADS)

Tkáč, Ondřej; Saha, Ashim K.; Loreau, Jérôme; Ma, Qianli; Dagdigian, Paul J.; Parker, David H.; van der Avoird, Ad; Orr-Ewing, Andrew J.

2015-12-01

Differential cross sections (DCSs) are reported for rotationally inelastic scattering of ND3 with H2, measured using a crossed molecular beam apparatus with velocity map imaging (VMI). ND3 molecules were quantum-state selected in the ground electronic and vibrational levels and, optionally, in the j±k = 11- rotation-inversion level prior to collisions. Inelastic scattering of state-selected ND3 with H2 was measured at the mean collision energy of 580 cm-1 by resonance-enhanced multiphoton ionisation spectroscopy and VMI of ND3 in selected single final j'±k' levels. Comparison of experimental DCSs with close-coupling quantum-mechanical scattering calculations serves as a test of a recently reported ab initio potential energy surface. Calculated integral cross sections reveal the propensities for scattering into various final j'±k' levels of ND3 and differences between scattering by ortho and para H2. Integral and differential cross sections are also computed at a mean collision energy of 430 cm-1 and compared to our recent results for inelastic scattering of state-selected ND3 with He.

Laser-induced multi-energy processing in diamond growth

NASA Astrophysics Data System (ADS)

Xie, Zhiqiang

Laser-induced multi-energy processing (MEP) introduces resonant vibrational excitations of precursor molecules to conventional chemical vapor deposition methods for material synthesis. In this study, efforts were extended to explore the capability of resonant vibrational excitations for promotion of energy efficiency in chemical reactions, for enhancement of diamond deposition, and for control of chemical reactions. The research project mainly focused on resonant vibrational excitations of precursor molecules using lasers in combustion flame deposition of diamond, which led to: 1) promotion of chemical reactions; 2) enhancement of diamond growth with higher growth rate and better crystallizations; 3) steering of chemical reactions which lead to preferential growth of {100}-oriented diamond films and crystals; and 4) mode-selective excitations of precursor molecules toward bond-selective control of chemical reactions. Diamond films and crystals were deposited in open air by combustion flame deposition through resonant vibrational excitations of precursor molecules, including ethylene (C2H4) and propylene (C3H 6). A kilowatt wavelength-tunable CO2 laser with spectral range from 9.2 to 10.9 microm was tuned to match vibrational modes of the precursor molecules. Resonant vibrational excitations of these molecules were achieved with high energy efficiency as compared with excitations using a common CO2 laser (fixed wavelength at 10.591microm). With resonant vibrational excitations, the diamond growth rate was increased; diamond quality was promoted; diamond crystals with lengths up to 5 mm were deposited in open air; preferential growth of {100}-oriented diamond films and single crystals was achieved; mode-selective excitations of precursor molecules were investigated toward control of chemical reactions. Optical emission spectroscopy (OES), mass spectrometry (MS), and molecular dynamic simulations were conducted to obtain an in-depth understanding of the resonant vibrational excitations. Species concentrations in flames without and with laser excitations under different wavelengths were investigated both experimentally and theoretically. Detection of C2, CH, and OH radicals, as well as CxHy species and their oxides (CxH yO) (x=1, 2; y=0˜5) using OES and MS, together with reaction pathway simulations, were used to explain the effect of vibrational excitations of precursor molecules on chemical reactions and on diamond depositions.

The relative importance of noise and vibration from railways.

PubMed

Howarth, H V; Griffin, M J

1990-06-01

An experiment was conducted to determine the subjective equivalence of railway noise and railway-induced building vibration, and hence the relative importance of the two stimuli. Six magnitudes of whole-body, vertical (z-axis) vibration and six levels of noise were presented simultaneously to each of 30 subjects in all 36 possible paired combinations. The stimuli were reproductions of the noise and vibration recorded inside a house during the passage of a train. The subjects were asked to indicate, after each presentation, which of the two stimuli (noise and vibration) they would prefer to be reduced. A seven-point scale was employed to indicate the total annoyance produced by the two stimuli. A subjective equivalence contour was determined from the levels at which 50% of the subjects preferred the reduction of noise and 50% preferred the reduction of vibration. The contour may be described by the relation L(AE) = 29.3 log10 VDV + 89.2, where L(AE) is the sound exposure level and VDV is the vibration dose value. This relation may be used to determine whether a reduction of noise or a reduction of vibration would be more beneficial to residents near railways. The total annoyance due to simultaneous noise and vibration was shown to depend on the magnitude of both stimuli.

POTENTIAL EFFECTS OF WHOLE-BODY VIBRATION EXERCISES ON BLOOD FLOW KINETICS OF DIFFERENT POPULATIONS: A SYSTEMATIC REVIEW WITH A SUITABLE APPROACH.

PubMed

Sá-Caputo, Danúbia; Paineiras-Domingos, Laisa; Carvalho-Lima, Rafaelle; Dias-Costa, Glenda; de Paiva, Patrícia de Castro; de Azeredo, Claudia Figueiredo; Carmo, Roberto Carlos Resende; Dionello, Carla F; Moreira-Marconi, Eloá; Frederico, Éric Heleno F F; Sousa-Gonçalves, Cintia Renata; Morel, Danielle S; Paiva, Dulciane N; Avelar, Núbia C P; Lacerda, Ana C; Magalhães, Carlos E V; Castro, Leonardo S; Presta, Giuseppe A; de Paoli, Severo; Sañudo, Borja; Bernardo-Filho, Mario

2017-01-01

The ability to control skin blood flow decreases with advancing age and some clinical disorders, as in diabetes and in rheumatologic diseases. Feasible clinical strategies such as whole-body vibration exercise (WBVE) are being used without a clear understanding of its effects. The aim of the present study is to review the effects of the WBVE on blood flow kinetics and its feasibility in different populations. The level of evidence (LE) of selected papers in PubMed and/or PEDRo databases was determined. We selected randomized, controlled trials in English to be evaluated. Six studies had LE II, one had LE III-2 and one III-3 according to the NHMRC. A great variability among the protocols was observed but also in the assessment devices; therefore, more research about this topic is warranted. Despite the limitations, it is can be concluded that the use of WBVE has proven to be a safe and useful strategy to improve blood flow. However, more studies with greater methodological quality are needed to clearly define the more suitable protocols.

Effect of whole body vibration on lactate level recovery and heart rate recovery in rest after intense exercise.

PubMed

Kang, Seung Rok; Min, Jin-Young; Yu, Changho; Kwon, Tae-Kyu

2017-07-20

In this paper, we investigated the recovery of the lactate level, muscular fatigue, and heart rate recovery (HRR) with respect to whole body vibration (WBV) during the rest stage after a gait exercise. A total of 24 healthy subjects with no medical history of exercise injury participated. The participants were divided into a training group with vibration during rest and a control group with the same conditions but without vibration. The subjects performed a gait exercise with a slope of 15% and velocity of 4 km/h to consume 450 kcal in 30 min. Then, they rested on a vibrating chair or on a chair without vibrations for 30 min. The vibration protocol consists of a frequency of 10 Hz and amplitude of 5 mm. To estimate the recovery effect, we measured the lactate levels in blood, spectral edge frequency (SEF) of MVIC, and HRR before, immediately after exercise, and after rest. The results showed that the lactate level in the training group decreased more (93.8%) than in the control group (32.8%). Also, HRR showed a similar trend with a recovery of 88.39% in the training group but 64.72% in the control group. We considered that whole-body vibrations during rest would help remove lactic acid by improving the level of lactic acid oxidation with stimulated blood vessels in the muscles and by helping to maintain blood flow. Also, WBV would lead to compensation to actively decrease the fast excess post-exercise oxygen consumption from blood circulation. We suggest that whole-body vibrations during rest can provide fast, efficient fatigue recovery as a cool down exercise for women, the elderly, and patients without other activity after intense exercise.

An assessment of spacecraft target mode selection methods

NASA Astrophysics Data System (ADS)

Mercer, J. F.; Aglietti, G. S.; Remedia, M.; Kiley, A.

2017-11-01

Coupled Loads Analyses (CLAs), using finite element models (FEMs) of the spacecraft and launch vehicle to simulate critical flight events, are performed in order to determine the dynamic loadings that will be experienced by spacecraft during launch. A validation process is carried out on the spacecraft FEM beforehand to ensure that the dynamics of the analytical model sufficiently represent the behavior of the physical hardware. One aspect of concern is the containment of the FEM correlation and update effort to focus on the vibration modes which are most likely to be excited under test and CLA conditions. This study therefore provides new insight into the prioritization of spacecraft FEM modes for correlation to base-shake vibration test data. The work involved example application to large, unique, scientific spacecraft, with modern FEMs comprising over a million degrees of freedom. This comprehensive investigation explores: the modes inherently important to the spacecraft structures, irrespective of excitation; the particular 'critical modes' which produce peak responses to CLA level excitation; an assessment of several traditional target mode selection methods in terms of ability to predict these 'critical modes'; and an indication of the level of correlation these FEM modes achieve compared to corresponding test data. Findings indicate that, although the traditional methods of target mode selection have merit and are able to identify many of the modes of significance to the spacecraft, there are 'critical modes' which may be missed by conventional application of these methods. The use of different thresholds to select potential target modes from these parameters would enable identification of many of these missed modes. Ultimately, some consideration of the expected excitations is required to predict all modes likely to contribute to the response of the spacecraft in operation.

On the use of the cross section concept as applied to pulsed CO2 laser dynamics

NASA Technical Reports Server (NTRS)

Flamant, P. H.; Menzies, R. T.

1985-01-01

The 'cross sections' which are commonly used in combination with the molecular vibrational level densities to describe induced transition rates are time dependent in a pulsed discharge. This greatly affects the relative rates of buildup of radiation at the various lines of a molecular gain medium in a nondispersive cavity, and the consequences for line selection by injection in a TEA-CO2 laser are discussed.

Testing of YUH-61A helicopter transmission in NASA Lewis 2240-kW (3000-hp facility

NASA Technical Reports Server (NTRS)

Mitchell, A. M.; Oswald, F. B.; Schuller, F. T.

1986-01-01

A helicopter transmission that was being considered for the Army's Utility Tactical Transport Attack System (UTTAS) was tested in the NASA Lewis 2240-kW (3000-hp) test facility to obtain the transmission's operational data. The results will form a vibration and efficiency data base for evaluation similar-class helicopter transmissions. The transmission's mechanical efficiency was determined to be 98.7 percent at its rated power level of 2080 kW (2792 hp). At power levels up to 113 percent of rated the transmission displayed 56 percent higher vibration acceleration levels on the right input than on the left input. Both vibration signature analysis and final visual inspection indicated that the right input spiral-bevel gear had poor contact patterns. The highest vibration meter level was 52 g's rms at the accessory gear, which had free-wheeling gearsets. At 113 percent power and 100 percent rated speed the vibration meter levels generally ranged from 3 to 25 g's rms.

Electron-Beam Mapping of Vibrational Modes with Nanometer Spatial Resolution.

PubMed

Dwyer, C; Aoki, T; Rez, P; Chang, S L Y; Lovejoy, T C; Krivanek, O L

2016-12-16

We demonstrate that a focused beam of high-energy electrons can be used to map the vibrational modes of a material with a spatial resolution of the order of one nanometer. Our demonstration is performed on boron nitride, a polar dielectric which gives rise to both localized and delocalized electron-vibrational scattering, either of which can be selected in our off-axial experimental geometry. Our experimental results are well supported by our calculations, and should reconcile current controversy regarding the spatial resolution achievable in vibrational mapping with focused electron beams.

APPARATUS FOR NON-DESTRUCTIVE INSPECTION OF CANTILEVERED MEMBERS

DOEpatents

Taylor, E.R.; Mahoney, C.H.; Lay, C.R.

1961-10-24

An apparatus for non-destructive inspection of cantilevered members, such as compressor blades, is described. The member under inspection is vibrated with a regulated source of air under pressure. The amplitude of vibration of the member is maintained at its natural frequency. The frequency of vibration of the member is measured. An indication of an excessive decay or erratic shifting in the measured frequency above an allowable hysteretic decay is provided as an indication of a fault in the member. The member is vibrated for a selected test period. (AEC)

Two-dimensional vibrational-electronic spectroscopy

NASA Astrophysics Data System (ADS)

Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira

2015-10-01

Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (νCN) and either a ligand-to-metal charge transfer transition ([FeIII(CN)6]3- dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN)5FeIICNRuIII(NH3)5]- dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific νCN modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a wide range of complex molecular, material, and biological systems.

Two-dimensional vibrational-electronic spectroscopy.

PubMed

Courtney, Trevor L; Fox, Zachary W; Slenkamp, Karla M; Khalil, Munira

2015-10-21

Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (νCN) and either a ligand-to-metal charge transfer transition ([Fe(III)(CN)6](3-) dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN)5Fe(II)CNRu(III)(NH3)5](-) dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific νCN modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a wide range of complex molecular, material, and biological systems.

Vibrational contribution to molecular polarizabilities and hyperpolarizabilities

NASA Astrophysics Data System (ADS)

Pandey, P. K. K.; Santry, D. P.

1980-09-01

The vibrational averaging theory of Kern and Matcha is extended, at the harmonic level of approximation, to the case where the molecular property under investigation can itself lead indirectly to a perturbation of the vibrational levels of the molecule. It is found that contributions arising from this perturbation can be significant, especially for molecular hyperpolarizabilities.

Coupled rotor/airframe vibration analysis

NASA Technical Reports Server (NTRS)

Sopher, R.; Studwell, R. E.; Cassarino, S.; Kottapalli, S. B. R.

1982-01-01

A coupled rotor/airframe vibration analysis developed as a design tool for predicting helicopter vibrations and a research tool to quantify the effects of structural properties, aerodynamic interactions, and vibration reduction devices on vehicle vibration levels is described. The analysis consists of a base program utilizing an impedance matching technique to represent the coupled rotor/airframe dynamics of the system supported by inputs from several external programs supplying sophisticated rotor and airframe aerodynamic and structural dynamic representation. The theoretical background, computer program capabilities and limited correlation results are presented in this report. Correlation results using scale model wind tunnel results show that the analysis can adequately predict trends of vibration variations with airspeed and higher harmonic control effects. Predictions of absolute values of vibration levels were found to be very sensitive to modal characteristics and results were not representative of measured values.

Effects of vibration and shock on the performance of gas-bearing space-power Brayton cycle turbomachinery. 2: Sinusoidal and random vibration

NASA Technical Reports Server (NTRS)

Tessarzik, J. M.; Chiang, T.; Badgley, R. H.

1973-01-01

The vibration response of a gas-bearing rotor-support system was analyzed experimentally documented for sinusoidal and random vibration environments. The NASA Brayton Rotating Unit (BRU), 36,000 rpm; 10 KWe turbogenerator; was subjected in the laboratory to sinusoidal and random vibrations to evaluate the capability of the BRU to (1) survive the vibration levels expected to be encountered during periods of nonoperation and (2) operate satisfactorily (that is, without detrimental bearing surface contacts) at the vibration levels expected during normal BRU operation. Response power spectral density was calculated for specified input random excitation, with particular emphasis upon the dynamic motions of the thrust bearing runner and stator. A three-mass model with nonlinear representation of the engine isolator mounts was used to calculate axial rotor-bearing shock response.

The acute effects of stretching with vibration on dynamic flexibility in young female gymnasts.

PubMed

Johnson, Aaron W; Warcup, Caisa N; Seeley, Matthew K; Eggett, Dennis; Feland, Jeffery B

2018-01-10

While stretching with vibration has been shown to improve static flexibility; the effect of stretching with vibration on dynamic flexibility is not well known. The purpose of this study was to examine the effectiveness of stretching with vibration on acute dynamic flexibility and jump height in novice and advanced competitive female gymnasts during a split jump. Female gymnast (n=27, age: 11.5 ± 1.7 years, Junior Olympic levels 5-10) participated in this cross-over study. Dynamic flexibility during gymnastic split jumps were video recorded and analyzed with Dartfish software. All participants completed both randomized stretching protocols with either the vibration platform turned on (VIB) (frequency of 30 Hz and 2 mm amplitude) or off (NoVIB) separated by 48 h. Participants performed 4 sets of three stretches on the vibration platform. Each stretch was held for 30 s with 5 s rest for a total of 7 min of stretch. Split jump flexibility decreased significantly from pre to post measurement in both VIB (-5.8°±5.9°) (p<0.001) and NoVIB (-2.6°±6.1°) (p=0.041) conditions (adjusted for gymnast level). This effect was greatest in lower skill level gymnasts (p=0.003), while the highest skill level gymnasts showed no significant decrease in the split jump (p=0.105). Jump height was not significantly different between conditions (p=0.892) or within groups (p=0.880). An acute session of static stretching with or without vibration immediately before performance does not alter jump height. Stretching with vibration immediately prior to gymnastics competition decreases split jump flexibility in lower level gymnasts more than upper level gymnasts.

Observation of Vibrational Relaxation Dynamics in X(sup 3)Sigma(sup -)(sub g) Oxygen Following Stimulated Raman Excitation to the v=1 Level: Implications for the RELIEF Flow Tagging Technique

NASA Technical Reports Server (NTRS)

Diskin, Glenn S.; Lempert, Walter R.; Miles, Richard B.

1996-01-01

The vibrational relaxation of ground-state molecular oxygen (O2, X(sup 3)Sigma(sup -)(sub g)) has been observed, following stimulated Raman excitation to the first excited vibrational level (v=1). Time delayed laser-induced fluorescence probing of the ro-vibrational population distribution was used to examine the temporal relaxation behavior. In the presence of water vapor, the relaxation process is rapid, and is dominated by near-resonant vibrational energy exchange between the v=1 level of O2 and the n2 bending mode of H2O. In the absence of H2O, reequilibration proceeds via homogeneous vibrational energy transfer, in which a collision between two v=1 O2 molecules leaves one molecule in the v=2 state and the other in the v=0 state. Subsequent collisions between molecules in v=1 and v>1 result in continued transfer of population up the vibrational ladder. The implications of these results for the RELIEF flow tagging technique are discussed.

Vibration Analysis of a Split Path Gearbox

NASA Technical Reports Server (NTRS)

Krantz, Timothy L.; Rashidi, Majid

1995-01-01

Split path gearboxes can be attractive alternatives to the common planetary designs for rotorcraft, but because they have seen little use, they are relatively high risk designs. To help reduce the risk of fielding a rotorcraft with a split path gearbox, the vibration and dynamic characteristics of such a gearbox were studied. A mathematical model was developed by using the Lagrangian method, and it was applied to study the effect of three design variables on the natural frequencies and vibration energy of the gearbox. The first design variable, shaft angle, had little influence on the natural frequencies. The second variable, mesh phasing, had a strong effect on the levels of vibration energy, with phase angles of 0 deg and 180 deg producing low vibration levels. The third design variable, the stiffness of the shafts connecting the spur gears to the helical pinions, strongly influenced the natural frequencies of some of the vibration modes, including two of the dominant modes. We found that, to achieve the lowest level of vibration energy, the natural frequencies of these two dominant modes should be less than those of the main excitation sources.

Vibration sensitivity of the scanning near-field optical microscope with a tapered optical fiber probe.

PubMed

Chang, Win-Jin; Fang, Te-Hua; Lee, Haw-Long; Yang, Yu-Ching

2005-01-01

In this paper the Rayleigh-Ritz method was used to study the scanning near-field optical microscope (SNOM) with a tapered optical fiber probe's flexural and axial sensitivity to vibration. Not only the contact stiffness but also the geometric parameters of the probe can influence the flexural and axial sensitivity to vibration. According to the analysis, the lateral and axial contact stiffness had a significant effect on the sensitivity of vibration of the SNOM's probe, each mode had a different level of sensitivity and in the first mode the tapered optical fiber probe was the most acceptive to higher levels of flexural and axial vibration. Generally, when the contact stiffness was lower, the tapered probe was more sensitive to higher levels of both axial and flexural vibration than the uniform probe. However, the situation was reversed when the contact stiffness was larger. Furthermore, the effect that the probe's length and its tapered angle had on the SNOM's probe axial and flexural vibration were significant and these two conditions should be incorporated into the design of new SNOM probes.

Experimental study of heat transfer enhancement due to the surface vibrations in a flexible double pipe heat exchanger

NASA Astrophysics Data System (ADS)

Hosseinian, A.; Meghdadi Isfahani, A. H.

2018-04-01

In this study, the heat transfer enhancement due to the surface vibration for a double pipe heat exchanger, made of PVDF, is investigated. In order to create forced vibrations (3-9 m/s2, 100 Hz) on the outer surface of the heat exchanger electro-dynamic vibrators are used. Experiments were performed at inner Reynolds numbers ranging from 2533 to 9960. The effects of volume flow rate and temperature on heat transfer performance are evaluated. Results demonstrated that heat transfer coefficient increases by increasing vibration level and mass flow rate. The most increase in heat transfer coefficient is 97% which is obtained for the highest vibration level (9 m/s2) in the experiment range.

Measurement of ground and nearby building vibration and noise induced by trains in a metro depot.

PubMed

Zou, Chao; Wang, Yimin; Wang, Peng; Guo, Jixing

2015-12-01

Metro depots are where subway trains are parked and where maintenance is carried out. They usually occupy the largest ground areas in metro projects. Due to land utilization problems, Chinese cities have begun to develop over-track buildings above metro depots for people's life and work. The frequently moving trains, when going into and out of metro depots, can cause excessive vibration and noise to over-track buildings and adversely affect the living quality of the building occupants. Considering the current need of reliable experimental data for the construction of metro depots, field measurements of vibration and noise on the ground and inside a nearby 3-story building subjected to moving subway trains were conducted in a metro depot at Guangzhou, China. The amplitudes and frequency contents of velocity levels were quantified and compared. The composite A-weighted equivalent sound levels and maximum sound levels were captured. The predicted models for vibration and noise of metro depot were proposed based on existing models and verified. It was found that the vertical vibrations were significantly greater than the horizontal vibrations on the ground and inside the building near the testing line. While at the throat area, the horizontal vibrations near the curved track were remarkably greater than the vertical vibrations. The attenuation of the vibrations with frequencies above 50 Hz was larger than the ones below 50 Hz, and the frequencies of vibration transmitting to adjacent buildings were mainly within 10-50 Hz. The largest equivalent sound level generated in the throat area was smaller than the testing line one, but the instantaneous maximum sound level induced by wheels squeal, contact between wheels and rail joints as well as turnout was close to or even greater than the testing line one. The predicted models gave a first estimation for design and assessment of newly built metro depots. Copyright © 2015 Elsevier B.V. All rights reserved.

A study on the contribution of body vibrations to the vibratory sensation induced by high-level, complex low-frequency noise.

PubMed

Takahashi, Yukio

2011-01-01

To investigate the contribution of body vibrations to the vibratory sensation induced by high-level, complex low-frequency noise, we conducted two experiments. In Experiment 1, eight male subjects were exposed to seven types of low-frequency noise stimuli: two pure tones [a 31.5-Hz, 100-dB(SPL) tone and a 50-Hz, 100-dB(SPL) tone] and five complex noises composed of the pure tones. For the complex noise stimuli, the sound pressure level of one tonal component was 100 dB(SPL) and that of another one was either 90, 95, or 100 dB(SPL). Vibration induced on the body surface was measured at five locations, and the correlation with the subjective rating of the vibratory sensation at each site of measurement was examined. In Experiment 2, the correlation between the body surface vibration and the vibratory sensation was similarly examined using seven types of noise stimuli composed of a 25-Hz tone and a 50-Hz tone. In both the experiments, we found that at the chest and the abdomen, the rating of the vibratory sensation was in close correlation with the vibration acceleration level (VAL) of the body surface vibration measured at each corresponding location. This was consistent with our previous results and suggested that at the trunk of the body (the chest and the abdomen), the mechanoreception of body vibrations plays an important role in the experience of the vibratory sensation in persons exposed to high-level low-frequency noise. At the head, however, no close correlation was found between the rating of the vibratory sensation and the VAL of body surface vibration. This suggested that at the head, the perceptual mechanisms of vibration induced by high-level low-frequency noise were different from those in the trunk of the body.

Journal of Engineering Thermophysics (Selected Articles),

DTIC Science & Technology

1983-05-20

A SURGE TEST OF A TWIN-SHAFT TURBOJET ENGINE ON GROUND TEST BED* Chiang Feng (Shengyang Aeroengine Company) ABSTRACT Instrument technique for...oscillogram for the static pressure behind the two compressors. This noise was analyzed and believed to have arisen from the vibrations of the rotating blades...booms are heard. The vibrational energy of the surge is enormous, especially in the range of 85-90% of rotational speed. One can feel the vibrations

Vibration isolation of automotive vehicle engine using periodic mounting systems

NASA Astrophysics Data System (ADS)

Asiri, S.

2005-05-01

Customer awareness and sensitivity to noise and vibration levels have been raised through increasing television advertisement, in which the vehicle noise and vibration performance is used as the main market differentiation. This awareness has caused the transportation industry to regard noise and vibration as important criteria for improving market shares. One industry that tends to be in the forefront of the technology to reduce the levels of noise and vibration is the automobile industry. Hence, it is of practical interest to reduce the vibrations induced structural responses. The automotive vehicle engine is the main source of mechanical vibrations of automobiles. The engine is vulnerable to the dynamic action caused by engine disturbance force in various speed ranges. The vibrations of the automotive vehicle engines may cause structural failure, malfunction of other parts, or discomfort to passengers because of high level noise and vibrations. The mounts of the engines act as the transmission paths of the vibrations transmitted from the excitation sources to the body of the vehicle and passengers. Therefore, proper design and control of these mounts are essential to the attenuation of the vibration of platform structures. To improve vibration resistant capacities of engine mounting systems, vibration control techniques may be used. For instance, some passive and semi-active dissipation devices may be installed at mounts to enhance vibration energy absorbing capacity. In the proposed study, a radically different concept is presented whereby periodic mounts are considered because these mounts exhibit unique dynamic characteristics that make them act as mechanical filters for wave propagation. As a result, waves can propagate along the periodic mounts only within specific frequency bands called the "Pass Bands" and wave propagation is completely blocked within other frequency bands called the "Stop Bands". The experimental arrangements, including the design of mounting systems with plain and periodic mounts will be studied first. The dynamic characteristics of such systems will be obtained experimentally in both cases. The tests will be then carried out to study the performance characteristics of periodic mounts with geometrical and/or material periodicity. The effectiveness of the periodicity on the vibration levels of mounting systems will be demonstrated theoretically and experimentally. Finally, the experimental results will be compared with the theoretical predictions.

Rapid-Adiabatic Control of Ro-Vibrational Populations in Polyatomic Molecules

NASA Astrophysics Data System (ADS)

Zak, Emil J.; Yachmenev, Andrey

2017-06-01

We present a simple method for control of ro-vibrational populations in polyatomic molecules in the presence of inhomogeneous electric fields [1]. Cooling and trapping of heavy polar polyatomic molecules has become one of the frontier goals in high-resolution molecular spectroscopy, especially in the context of parity violation measurement in chiral compounds [2]. A key step toward reaching this goal would be development of a robust and efficient protocol for control of populations of ro-vibrational states in polyatomic, often floppy molecules. Here we demonstrate a modification of the stark-chirped rapid-adiabatic-passage technique (SCRAP) [3], designed for achieving high levels of control of ro-vibrational populations over a selected region in space. The new method employs inhomogeneous electric fields to generate space- and time- controlled Stark-shifts of energy levels in molecules. Adiabatic passage between ro-vibrational states is enabled by the pump pulse, which raises the value of the Rabi frequency. This Stark-chirped population transfer can be used in manipulation of population differences between high-field-seeking and low-field-seeking states of molecules in the Stark decelerator [4]. Appropriate timing of voltages on electric rods located along the decelerator combined with a single pump laser renders our method as potentially more efficient than traditional Stark decelerator techniques. Simulations for NH_3 show significant improvement in effectiveness of cooling, with respect to the standard 'moving-potential' method [5]. At the same time a high phase-space acceptance of the molecular packet is maintained. E. J. Zak, A. Yachmenev (submitted). C. Medcraft, R. Wolf, M. Schnell, Angew. Chem. Int. Ed., 53, 43, 11656-11659 (2014) M. Oberst, H. Munch, T. Halfman, PRL 99, 173001 (2007). K. Wohlfart, F. Grätz, F. Filsinger, H. Haak, G. Meijer, J. Küpper, Phys. Rev. A 77, 031404(R) (2008). H. L. Bethlem, F. M. H. Crompvoets, R. T. Jongma, S. Y. T. van de Meerakker, G. Meijer, Phys. Rev. A, 65, 053416 (2002).

Picosecond excite-and-probe absorption measurement of the intra-2E(g)E(3/2)-state vibrational relaxation time in Ti(3+):Al2O3

NASA Technical Reports Server (NTRS)

Gayen, S. K.; Wang, W. B.; Petricevic, V.; Yoo, K. M.; Alfano, R. R.

1987-01-01

The Ti(3+)-doped Al2O3 has been recently demonstrated to be a tunable solid-state laser system with Ti(3+) as the laser-active ion. In this paper, the kinetics of vibrational transitions in the 2E(g)E(3/2) electronic state of Ti(3+):Al2O3a (crucial for characterizing new host materials for the Ti ion) was investigated. A 527-nm 5-ps pulse was used to excite a band of higher vibrational levels of the 2E(g)E(3/2) state, and the subsequent growth of population in the zero vibrational level and lower vibrational levels was monitored by a 3.9-micron picosecond probe pulse. The time evolution curve in the excited 2E(g)E(3/2) state at room temperature was found to be characterized by a sharp rise followed by a long decay, the long lifetime decay reflecting the depopulation of the zero and the lower vibrational levels of the 2E(g)E(3/2) state via radiative transitions. An upper limit of 3.5 ps was estimated for intra-2E(g)E(3/2)-state vibrational relaxation time.

Criteria for acceptable levels of the Shinkansen Super Express train noise and vibration in residential areas

NASA Astrophysics Data System (ADS)

Yamanaka, K.; Nakagawa, T.; Kobayashi, F.; Kanada, S.; Tanahashi, M.; Muramatsu, T.; Yamada, S.

1982-10-01

A survey of 1187 housewives living in 18 areas along the Shinkansen Super Express (bullet train) railway was conducted by means of a self-administered health questionnaire (modified Cornell Medical Index). In addition, geographically corresponding measurements of noise level and vibration intensity were taken. The relationship of noise and vibration to positive responses (health complaints) related to bodily symptoms, illness and emotional disturbances was analyzed. The factors which correlated with an increase in the average number of positive responses included noise, vibration, age and health status. Such factors as marital status, educational level, part time work, duration of inhabitancy and occupation of the head of the houshold correlated poorly with the number of positive responses. Unhealthy respondents compared to healthy respondents are more frequently affected by noise and vibration. The rate of positive responses in the visual, respiratory, cardiovascular, digestive and nervous systems, sleep disturbances and emotional disturbances increased accordingly as noise and vibration increased. Combined effects of noise and vibration stimuli on the total number of positive responses (an indicator of general health) were found. This study has produced results indicating that the maximum permissible noise level should not exceed 70 dB(A) in the residential areas along the Shinkansen railway.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kearney, Steven; Shu, Deming

A vibration survey of the APS experiment hall floor was conducted. It was found that beamlines 10-20 have particularly low levels of vibration when compared to the rest of the facility. The vibration spectrum for each beamline floor can be found in the appendix. Throughout the majority of the 5-100 Hz vibration spectrum beamlines at the APS fall below the most stringent NEST vibration criteria. Lastly, it was concluded that the magnitude of vibrations at a particular beamline is largely dependent upon the magnitude of vibrations present at the nearby mezzanine support column.

Insight into the Selectivity of Isopropanol Conversion at Strontium Titanate (100) Surfaces: A Combination Kinetic and Spectroscopic Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Shuai; Grey, Matthew B.; Kidder, Michelle

This work aims to better understand the role of interfacial molecular structure that governs selectivity and activity in heterogeneous catalytic reactions. To address this, a comprehensive study of isopropanol conversion over an archetypal perovskite material, strontium titanate (SrTiO 3 or STO), was performed with an array of techniques sensitive to orthogonal aspects of the ensuing chemistry. Cubic-shape STO nanoparticles with only the (100) facet exposed were synthesized and used to study the ensemble kinetic conversion of isopropanol over the surfaces, which showed a remarkable selectivity to form acetone, with minor propylene products appearing at elevated temperatures. These results in combinationmore » with inelastic neutron scattering measurements provide not only new insight into the selectivity and overall activity of the catalysts but also low frequency vibrational signatures of the adsorbed and reacted species. To compliment these measurements, pristine thin films of STO (100) were synthesized and used in combination with vibrational sum frequency generation spectroscopy to extract the absolute molecular orientation of the adsorbed molecules at the interface. It was found that the isopropanol assumes an orientation where the -CH group points towards the STO surface; this pre-reaction geometry offers an obvious pathway to produce acetone by abstracting the alpha-proton and, thus, provides a mechanistic explanation of selectivity at STO (100) surfaces. This new insight opens up pathways to explore and modify surfaces to tune the activity/selectivity though a molecular level understanding of the reactions at the surface.« less

Insight into the Selectivity of Isopropanol Conversion at Strontium Titanate (100) Surfaces: A Combination Kinetic and Spectroscopic Study

DOE PAGES

Tan, Shuai; Grey, Matthew B.; Kidder, Michelle; ...

2017-10-13

This work aims to better understand the role of interfacial molecular structure that governs selectivity and activity in heterogeneous catalytic reactions. To address this, a comprehensive study of isopropanol conversion over an archetypal perovskite material, strontium titanate (SrTiO 3 or STO), was performed with an array of techniques sensitive to orthogonal aspects of the ensuing chemistry. Cubic-shape STO nanoparticles with only the (100) facet exposed were synthesized and used to study the ensemble kinetic conversion of isopropanol over the surfaces, which showed a remarkable selectivity to form acetone, with minor propylene products appearing at elevated temperatures. These results in combinationmore » with inelastic neutron scattering measurements provide not only new insight into the selectivity and overall activity of the catalysts but also low frequency vibrational signatures of the adsorbed and reacted species. To compliment these measurements, pristine thin films of STO (100) were synthesized and used in combination with vibrational sum frequency generation spectroscopy to extract the absolute molecular orientation of the adsorbed molecules at the interface. It was found that the isopropanol assumes an orientation where the -CH group points towards the STO surface; this pre-reaction geometry offers an obvious pathway to produce acetone by abstracting the alpha-proton and, thus, provides a mechanistic explanation of selectivity at STO (100) surfaces. This new insight opens up pathways to explore and modify surfaces to tune the activity/selectivity though a molecular level understanding of the reactions at the surface.« less

Vibration Induced Osteogenic Commitment of Mesenchymal Stem Cells is Enhanced by Cytoskeletal Remodeling but not Fluid Shear

PubMed Central

Uzer, Gunes; Pongkitwitoon, Suphannee; Chan, M Ete; Judex, Stefan

2013-01-01

Consistent across studies in humans, animals and cells, the application of vibrations can be anabolic and/or anti-catabolic to bone. The physical mechanisms modulating the vibration-induced response have not been identified. Recently, we developed an in vitro model in which candidate parameters including acceleration magnitude and fluid shear can be controlled independently during vibrations. Here, we hypothesized that vibration induced fluid shear does not modulate mesenchymal stem cell (MSC) proliferation and mineralization and that cell’s sensitivity to vibrations can be promoted via actin stress fiber formation. Adipose derived human MSCs were subjected to vibration frequencies and acceleration magnitudes that induced fluid shear stress ranging from 0.04Pa to 5Pa. Vibrations were applied at magnitudes of 0.15g, 1g, and 2g using frequencies of both 100Hz and 30Hz. After 14d and under low fluid shear conditions associated with 100Hz oscillations, mineralization was greater in all vibrated groups than in controls. Greater levels of fluid shear produced by 30Hz vibrations enhanced mineralization only in the 2g group. Over 3d, vibrations led to the greatest increase in total cell number with the frequency/acceleration combination that induced the smallest level of fluid shear. Acute experiments showed that actin remodeling was necessary for early mechanical up-regulation of RUNX-2 mRNA levels. During osteogenic differentiation, mechanically induced up-regulation of actin remodeling genes including Wiskott-Aldrich syndrome (WAS) protein, a critical regulator of Arp2/3 complex, was related to the magnitude of the applied acceleration but not to fluid shear. These data demonstrate that fluid shear does not regulate vibration induced proliferation and mineralization and that cytoskeletal remodeling activity may play a role in MSC mechanosensitivity. PMID:23870506

Birge-Sponer Estimation of the C-H Bond Dissociation Energy in Chloroform Using Infrared, Near-Infrared, and Visible Absorption Spectroscopy: An Experiment in Physical Chemistry

ERIC Educational Resources Information Center

Myrick, M. L.; Greer, A. E.; Nieuwland, A. A.; Priore, R. J.; Scaffidi, J.; Andreatta, Danielle; Colavita, Paula

2008-01-01

The fundamental and overtone vibrational absorption spectroscopy of the C-H unit in CHCl[subscript 3] is measured for transitions from the v = 0 energy level to v = 1 through v = 5 energy levels. The energies of the transitions exhibit a linearly-decreasing spacing between adjacent vibrational levels as the vibrational quantum number increases.…

Thermally and vibrationally induced conformational isomerizations, infrared spectra, and photochemistry of gallic acid in low-temperature matrices

NASA Astrophysics Data System (ADS)

Justino, Licínia L. G.; Reva, Igor; Fausto, Rui

2016-07-01

Near-infrared (near-IR) narrowband selective vibrational excitation and annealing of gallic acid (3,4,5-trihydroxybenzoic acid) isolated in cryogenic matrices were used to induce interconversions between its most stable conformers. The isomerizations were probed by infrared spectroscopy. An extensive set of quantum chemical calculations, carried out at the DFT(B3LYP)/6-311++G(d,p) level of approximation, was used to undertake a detailed analysis of the ground state potential energy surface of the molecule. This investigation of the molecule conformational space allowed extracting mechanistic insights into the observed annealing- or near-IR-induced isomerization processes. The infrared spectra of the two most stable conformers of gallic acid in N2, Xe, and Ar matrices were fully assigned. Finally, the UV-induced photochemistry of the matrix isolated compound was investigated.

Luminorefrigeration: vibrational cooling of NaCs.

PubMed

Wakim, A; Zabawa, P; Haruza, M; Bigelow, N P

2012-07-02

We demonstrate the use of optical pumping of kinetically ultracold NaCs to cool an initial vibrational distribution of electronic ground state molecules X(1)Σ(+)(v ≥ 4) into the vibrational ground state X(1)Σ(+)(v=0). Our approach is based on the use of simple, commercially available multimode diode lasers selected to optically pump population into X(1)Σ(+)(v=0). We investigate the impact of the cooling process on the rotational state distribution of the vibrational ground state, and observe that an initial distribution, J(initial)=0-2 is only moderately affected resulting in J(final)=0-4. This method provides an inexpensive approach to creation of vibrational ground state ultracold polar molecules.

Vibration Analysis of Composite Laminate Plate Excited by Piezoelectric Actuators

PubMed Central

Her, Shiuh-Chuan; Lin, Chi-Sheng

2013-01-01

Piezoelectric materials can be used as actuators for the active vibration control of smart structural systems. In this work, piezoelectric patches are surface bonded to a composite laminate plate and used as vibration actuators. A static analysis based on the piezoelectricity and elasticity is conducted to evaluate the loads induced by the piezoelectric actuators to the host structure. The loads are then employed to develop the vibration response of a simply supported laminate rectangular plate excited by piezoelectric patches subjected to time harmonic voltages. An analytical solution of the vibration response of a simply supported laminate rectangular plate under time harmonic electrical loading is obtained and compared with finite element results to validate the present approach. The effects of location and exciting frequency of piezoelectric actuators on the vibration response of the laminate plate are investigated through a parametric study. Numerical results show that modes can be selectively excited, leading to structural vibration control. PMID:23529121

Irisin in response to acute and chronic whole-body vibration exercise in humans.

PubMed

Huh, Joo Young; Mougios, Vassilis; Skraparlis, Athanasios; Kabasakalis, Athanasios; Mantzoros, Christos S

2014-07-01

Irisin is a recently identified myokine, suggested to mediate the beneficial effects of exercise by inducing browning of white adipocytes and thus increasing energy expenditure. In humans, the regulation of irisin by exercise is not completely understood. We investigated the effect of acute and chronic whole-body vibration exercise, a moderate-intensity exercise that resembles shivering, on circulating irisin levels in young healthy subjects. Healthy untrained females participated in a 6-week program of whole-body vibration exercise training. Blood was drawn before and immediately after an acute bout of exercise at baseline (week 0) and after 6 weeks of training. The resting irisin levels were not different at baseline (week 0) and after 6 weeks of training. At both 0 and 6 weeks of training, an acute bout of vibration exercise significantly elevated circulating irisin levels by 9.5% and 18.1%, respectively (p=0.05 for the percent change of irisin levels). Acute bouts of whole-body vibration exercise are effective in increasing circulating irisin levels but chronic training does not change levels of baseline irisin levels in humans. Copyright © 2014 Elsevier Inc. All rights reserved.

Vibration Sensitivity of a Wide-Temperature Electronically Scanned Pressure Measurement (ESP) Module

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J.; Garza, Frederico R.

2001-01-01

A vibration sensitivity test was conducted on a Wide-Temperature ESP module. The test object was Module "M4," a 16-channel, 4 psi unit scheduled for installation in the Arc Sector of NTF. The module was installed on a vibration exciter and loaded to positive then negative full-scale pressures (+/-2.5 psid). Test variables were the following: Vibration frequencies: 20, 55, 75 Hz. Vibration level: 1 g. Vibration axes: X, Y, Z. The pressure response was measured on each channel, first without and then with the vibration turned on, and the difference analyzed by means of the statistical t-test. The results show that the vibration sensitivity does not exceed 0.01% Full Scale Output per g (with the exception of one channel on one axis) to a 95 percent confidence level. This specification, limited by the resolution of the pressure source, lies well below the total uncertainty specification of 0.1 percent Full Scale Output.

Vibrational force alters mRNA expression in osteoblasts

NASA Technical Reports Server (NTRS)

Tjandrawinata, R. R.; Vincent, V. L.; Hughes-Fulford, M.

1997-01-01

Serum-deprived mouse osteoblastic (MC3T3E1) cells were subjected to a vibrational force modeled by NASA to simulate a space shuttle launch (7.83 G rms). The mRNA levels for eight genes were investigated to determine the effect of vibrational force on mRNA expression. The mRNA levels of two growth-related protooncogenes, c-fos and c-myc, were up-regulated significantly within 30 min after vibration, whereas those of osteocalcin as well as transforming growth factor-beta1 were decreased significantly within 3 h after vibration. No changes were detected in the levels of beta-actin, histone H4, or cytoplasmic phospholipase A2 after vibration. No basal levels of cyclooxygenase-2 expression were detected. In addition, the extracellular concentrations of prostaglandin E2 (PGE2), a potent autocrine/paracrine growth factor in bone, were not significantly altered after vibration most likely due to the serum deprivation state of the osteoblasts. In comparison with the gravitational launch profile, vibrational-induced changes in gene expression were greater both in magnitude and number of genes activated. Taken together, these data suggest that the changes in mRNA expression are due to a direct mechanical effect of the vibrational force on the osteoblast cells and not to changes in the local PGE2 concentrations. The finding that launch forces induce gene expression is of utmost importance since many of the biological experiments do not dampen vibrational loads on experimental samples. This lack of dampening of vibrational forces may partially explain why 1-G onboard controls sometimes do not reflect 1-G ground controls. These data may also suggest that scientists use extra ground controls that are exposed to launch forces, have these forces dampened on launched samples, or use facilities such as Biorack that provide an onboard 1-G centrufuge in order to control for space shuttle launch forces.

Coupling between plate vibration and acoustic radiation

NASA Technical Reports Server (NTRS)

Frendi, Abdelkader; Maestrello, Lucio; Bayliss, Alvin

1992-01-01

A detailed numerical investigation of the coupling between the vibration of a flexible plate and the acoustic radiation is performed. The nonlinear Euler equations are used to describe the acoustic fluid while the nonlinear plate equation is used to describe the plate vibration. Linear, nonlinear, and quasi-periodic or chaotic vibrations and the resultant acoustic radiation are analyzed. We find that for the linear plate response, acoustic coupling is negligible. However, for the nonlinear and chaotic responses, acoustic coupling has a significant effect on the vibration level as the loading increases. The radiated pressure from a plate undergoing nonlinear or chaotic vibrations is found to propagate nonlinearly into the far-field. However, the nonlinearity due to wave propagation is much weaker than that due to the plate vibrations. As the acoustic wave propagates into the far-field, the relative difference in level between the fundamental and its harmonics and subharmonics decreases with distance.

Combined Effects of High-Speed Railway Noise and Ground Vibrations on Annoyance

PubMed Central

Yokoshima, Shigenori; Morihara, Takashi; Sato, Tetsumi; Yano, Takashi

2017-01-01

The Shinkansen super-express railway system in Japan has greatly increased its capacity and has expanded nationwide. However, many inhabitants in areas along the railways have been disturbed by noise and ground vibration from the trains. Additionally, the Shinkansen railway emits a higher level of ground vibration than conventional railways at the same noise level. These findings imply that building vibrations affect living environments as significantly as the associated noise. Therefore, it is imperative to quantify the effects of noise and vibration exposures on each annoyance under simultaneous exposure. We performed a secondary analysis using individual datasets of exposure and community response associated with Shinkansen railway noise and vibration. The data consisted of six socio-acoustic surveys, which were conducted separately over the last 20 years in Japan. Applying a logistic regression analysis to the datasets, we confirmed the combined effects of vibration/noise exposure on noise/vibration annoyance. Moreover, we proposed a representative relationship between noise and vibration exposures, and the prevalence of each annoyance associated with the Shinkansen railway. PMID:28749452

Kinetic study of low-temperature CO2 plasmas under non-equilibrium conditions. I. Relaxation of vibrational energy

NASA Astrophysics Data System (ADS)

Silva, T.; Grofulović, M.; Klarenaar, B. L. M.; Morillo-Candas, A. S.; Guaitella, O.; Engeln, R.; Pintassilgo, C. D.; Guerra, V.

2018-01-01

A kinetic model describing the time evolution of ˜70 individual CO2(X1Σ+) vibrational levels during the afterglow of a pulsed DC glow discharge is developed in order to contribute to the understanding of vibrational energy transfer in CO2 plasmas. The results of the simulations are compared against in situ Fourier transform infrared spectroscopy data obtained in a pulsed DC glow discharge and its afterglow at pressures of a few Torr and discharge currents of around 50 mA. The very good agreement between the model predictions and the experimental results validates the kinetic scheme considered here and the corresponding vibration-vibration and vibration-translation rate coefficients. In this sense, it establishes a reaction mechanism for the vibrational kinetics of these CO2 energy levels and offers a firm basis to understand the vibrational relaxation in CO2 plasmas. It is shown that first-order perturbation theories, namely, the Schwartz-Slawsky-Herzfeld and Sharma-Brau methods, provide a good description of CO2 vibrations under low excitation regimes.

Vibrational quasi-degenerate perturbation theory with optimized coordinates: applications to ethylene and trans-1,3-butadiene.

PubMed

Yagi, Kiyoshi; Otaki, Hiroki

2014-02-28

A perturbative extension to optimized coordinate vibrational self-consistent field (oc-VSCF) is proposed based on the quasi-degenerate perturbation theory (QDPT). A scheme to construct the degenerate space (P space) is developed, which incorporates degenerate configurations and alleviates the divergence of perturbative expansion due to localized coordinates in oc-VSCF (e.g., local O-H stretching modes of water). An efficient configuration selection scheme is also implemented, which screens out the Hamiltonian matrix element between the P space configuration (p) and the complementary Q space configuration (q) based on a difference in their quantum numbers (λpq = ∑s|ps - qs|). It is demonstrated that the second-order vibrational QDPT based on optimized coordinates (oc-VQDPT2) smoothly converges with respect to the order of the mode coupling, and outperforms the conventional one based on normal coordinates. Furthermore, an improved, fast algorithm is developed for optimizing the coordinates. First, the minimization of the VSCF energy is conducted in a restricted parameter space, in which only a portion of pairs of coordinates is selectively transformed. A rational index is devised for this purpose, which identifies the important coordinate pairs to mix from others that may remain unchanged based on the magnitude of harmonic coupling induced by the transformation. Second, a cubic force field (CFF) is employed in place of a quartic force field, which bypasses intensive procedures that arise due to the presence of the fourth-order force constants. It is found that oc-VSCF based on CFF together with the pair selection scheme yields the coordinates similar in character to the conventional ones such that the final vibrational energy is affected very little while gaining an order of magnitude acceleration. The proposed method is applied to ethylene and trans-1,3-butadiene. An accurate, multi-resolution potential, which combines the MP2 and coupled-cluster with singles, doubles, and perturbative triples level of electronic structure theory, is generated and employed in the oc-VQDPT2 calculation to obtain the fundamental tones as well as selected overtones/combination tones coupled to the fundamentals through the Fermi resonance. The calculated frequencies of ethylene and trans-1,3-butadiene are found to be in excellent agreement with the experimental values with a mean absolute error of 8 and 9 cm(-1), respectively.

A non-local thermodynamic equilibrium radiative transfer model for ingrared emissions in the atmosphere of Mars. 1: Theoretical basis and nighttime populations of vibrational levels

NASA Astrophysics Data System (ADS)

Lopez-Valverde, M. A.; Lopez-Puertas, M.

1994-06-01

A radiative transfer model to study the infrared (1-20 micrometer) emissions of the CO and CO2 molecules in the atmosphere of Mars has been developed. The model runs from the planet's surface up to 180 km and has been especially elaborated to study non-local thermodynamic equilibrium (non-LTE) situations. it includes the most important energy levels and vibration-rotation bands able to give a significant atmospheric emission or produce a significant cooling/heating rate. Exchanges of energy in thermal and nonthermal (vibrational-vibrational) collisions as well as by radiative processes have been included. An exhaustive review of the rate constants for vibrational-thermal and vibrational-vibrational collisional exchanges has been carried out. Radiative transfer processes have been treated by using a modified Curtis matrix formulation. The populations of the excited vibrational levels for nighttime conditions are presented along with a sensitivity study of their variations to the kinetic temperature profile and to collisional rate constants. The populations of the CO2(0, nu2, 0) levels follow LTE up to about 85 km with the radiative transfer processes playing a very important role in maintaining this situation above the tropopause. This result is pratically insensitive to plausible variations in the kinetic temperature of the troposphere. The uncertainties in the rate constants play an important role in determining the populations of the levels at thermospheric altitudes, but they are of little significance for the heights where they start departing from LTE. The CO2(0, 00, 1) level breaks down from LTE at about 60 km, the laser bands at 10 micrometers giving a significant contribution to its population in the Martian mesosphere. The CO(1) level stars departing around 50 km and is noticeably enhanced in the upper thermosphere by absorption of upwelling flux from the planets' surface.

National Transonic Facility model and model support vibration problems

NASA Technical Reports Server (NTRS)

Young, Clarence P., Jr.; Popernack, Thomas G., Jr.; Gloss, Blair B.

1990-01-01

Vibrations of models and model support system were encountered during testing in the National Transonic Facility. Model support system yaw plane vibrations have resulted in model strain gage balance design load limits being reached. These high levels of vibrations resulted in limited aerodynamic testing for several wind tunnel models. The yaw vibration problem was the subject of an intensive experimental and analytical investigation which identified the primary source of the yaw excitation and resulted in attenuation of the yaw oscillations to acceptable levels. This paper presents the principal results of analyses and experimental investigation of the yaw plane vibration problems. Also, an overview of plans for development and installation of a permanent model system dynamic and aeroelastic response measurement and monitoring system for the National Transonic Facility is presented.

Vibration criteria for transit systems in close proximity to university research activities

NASA Astrophysics Data System (ADS)

Wolf, Steven

2004-05-01

As some of the newer LRT projects get closer to research facilities the question arisesi ``how do you assess the potential impact of train operations on the activities within these types of facilities?'' There are several new LRT projects that have proposed alignments near or under university research facilities. The traditional ground vibration analysis at these locations is no longer valid but requires a more sophisticated approach to identifying both criteria and impact. APTA, ISO, IES, and FTA vibration criteria may not be adequate for the most sensitive activities involving single cell and nano technology research. The use of existing ambient vibration levels is evaluated as a potential criteria. A statistical approach is used to better understand how the train vibration would affect the ambient vibration levels.

An experimental study for determining human discomfort response to roll vibration

NASA Technical Reports Server (NTRS)

Leatherwood, J. D.; Dempsey, T. K.; Clevenson, S. A.

1976-01-01

An experimental study using a passenger ride quality apparatus (PRQA) was conducted to determine the subjective reactions of passengers to roll vibrations. The data obtained illustrate the effect upon human comfort of several roll-vibration parameters: namely, roll acceleration level, roll frequency, and seat location (i.e., distance from axis of rotation). Results of an analysis of variance indicated that seat location had no effect on discomfort ratings of roll vibrations. The effect of roll acceleration level was significant, and discomfort ratings increased markedly with increasing roll acceleration level at all roll frequencies investigated. Of particular interest, is the fact that the relationship between discomfort ratings and roll acceleration level was linear in nature. The effect of roll frequency also was significant as was the interaction between roll acceleration level and roll frequency.

Programmable Calculator Use in Undergraduate Dynamics, Vibrations, and Elementary Structures Courses.

ERIC Educational Resources Information Center

Cutchins, M. A.

1982-01-01

Presents programmable calculator solutions to selected problems, including area moments of inertia and principal values, the 2-D principal stress problem, C.G. and pitch inertia computations, 3-D eigenvalue problems, 3 DOF vibrations, and a complex flutter determinant. (SK)

The Effect of Single-Level Disc Degeneration on Dynamic Response of the Whole Lumbar Spine to Vertical Vibration.

PubMed

Guo, Li-Xin; Fan, Wei

2017-09-01

The objective of this study was to investigate the effect of single-level disc degeneration on dynamic response of the whole lumbar spine to vertical whole body vibration that is typically present when driving vehicles. Ligamentous finite element models of the lumbar L1-S1 motion segment in different grades of degeneration (healthy, mild, and moderate) at the L4-L5 level were developed with consideration of changing disc height and material properties of the nucleus pulpous. All models were loaded with a compressive follower preload of 400 N and a sinusoidal vertical vibration load of ±40 N. After transient dynamic analyses, computational results for the 3 models in terms of disc bulge, von-Mises stress in annulus ground substance, and nucleus pressure were plotted as a function of time and compared. All the predicted results showed a cyclic response with time. At the degenerated L4-L5 disc level, as degeneration progressed, maximum value of the predicted response showed a decrease in disc bulge and von-Mises stress in annulus ground substance but a slight increase in nucleus pressure, and their vibration amplitudes were all decreased. At the adjacent levels of the degenerated disc, there was a slight decrease in maximum value and vibration amplitude of these predicted responses with the degeneration. The results indicated that single-level disc degeneration can alter vibration characteristics of the whole lumbar spine especially for the degenerated disc level, and increasing the degeneration did not deteriorate the effect of vertical vibration on the spine. Copyright © 2017 Elsevier Inc. All rights reserved.

What Can Be Learned from Nuclear Resonance Vibrational Spectroscopy: Vibrational Dynamics and Hemes

PubMed Central

2017-01-01

Nuclear resonance vibrational spectroscopy (NRVS; also known as nuclear inelastic scattering, NIS) is a synchrotron-based method that reveals the full spectrum of vibrational dynamics for Mössbauer nuclei. Another major advantage, in addition to its completeness (no arbitrary optical selection rules), is the unique selectivity of NRVS. The basics of this recently developed technique are first introduced with descriptions of the experimental requirements and data analysis including the details of mode assignments. We discuss the use of NRVS to probe 57Fe at the center of heme and heme protein derivatives yielding the vibrational density of states for the iron. The application to derivatives with diatomic ligands (O2, NO, CO, CN–) shows the strong capabilities of identifying mode character. The availability of the complete vibrational spectrum of iron allows the identification of modes not available by other techniques. This permits the correlation of frequency with other physical properties. A significant example is the correlation we find between the Fe–Im stretch in six-coordinate Fe(XO) hemes and the trans Fe–N(Im) bond distance, not possible previously. NRVS also provides uniquely quantitative insight into the dynamics of the iron. For example, it provides a model-independent means of characterizing the strength of iron coordination. Prediction of the temperature-dependent mean-squared displacement from NRVS measurements yields a vibrational “baseline” for Fe dynamics that can be compared with results from techniques that probe longer time scales to yield quantitative insights into additional dynamical processes. PMID:28921972

Analysis of muscle activation in each body segment in response to the stimulation intensity of whole-body vibration.

PubMed

Lee, Dae-Yeon

2017-02-01

[Purpose] The purpose of this study was to investigate the effects of a whole-body vibration exercise, as well as to discuss the scientific basis to establish optimal intensity by analyzing differences between muscle activations in each body part, according to the stimulation intensity of the whole-body vibration. [Subjects and Methods ] The study subjects included 10 healthy men in their 20s without orthopedic disease. Representative muscles from the subjects' primary body segments were selected while the subjects were in upright positions on exercise machines; electromyography electrodes were attached to the selected muscles. Following that, the muscle activities of each part were measured at different intensities. No vibration, 50/80 in volume, and 10/25/40 Hz were mixed and applied when the subjects were on the whole-vibration exercise machines in upright positions. After that, electromyographic signals were collected and analyzed with the root mean square of muscular activation. [Results] As a result of the analysis, it was found that the muscle activation effects had statistically meaningful differences according to changes in exercise intensity in all 8 muscles. When the no-vibration status was standardized and analyzed as 1, the muscle effect became lower at higher frequencies, but became higher at larger volumes. [Conclusion] In conclusion, it was shown that the whole-body vibration stimulation promoted muscle activation across the entire body part, and the exercise effects in each muscle varied depending on the exercise intensities.

The near infrared spectrum of ozone by CW-cavity ring down spectroscopy between 5850 and 7000 cm(-1): new observations and exhaustive review.

PubMed

Campargue, A; Barbe, A; De Backer-Barilly, M-R; Tyuterev, Vl G; Kassi, S

2008-05-28

Weak vibrational bands of (16)O(3) could be detected in the 5850-7030 cm(-1) spectral region by CW-cavity ring down spectroscopy using a set of fibered DFB diode lasers. As a result of the high sensitivity (noise equivalent absorption alpha(min) approximately 3 x 10(-10) cm(-1)), bands reaching a total of 16 upper vibrational states have been previously reported in selected spectral regions. In the present report, the analysis of the whole investigated region is completed by new recordings in three spectral regions which have allowed: (i) a refined analysis of the nu(1) + 3nu(2) + 3nu(3) band from new spectra in the 5850-5900 cm(-1) region; (ii) an important extension of the assignments of the 2nu(1)+5nu(3) and 4nu(1) + 2nu(2) + nu(3) bands in the 6500-6600 cm(-1) region, previously recorded by frequency modulation diode laser spectroscopy. The rovibrational assignments of the weak 4nu(1) + 2nu(2) + nu(3) band were fully confirmed by the new observation of the 4nu(1) + 2nu(2) + nu(3)- nu(2) hot band near 5866.9 cm(-1) reaching the same upper state; (iii) the observation and modelling of three A-type bands at 6895.51, 6981.87 and 6990.07 cm(-1) corresponding to the highest excited vibrational bands of ozone detected so far at high resolution. The upper vibrational states were assigned by comparison of their energy values with calculated values obtained from the ground state potential energy surface of (16)O(3). The vibrational mixing and consequently the ambiguities in the vibrational labelling are discussed. For each band or set of interacting bands, the spectroscopic parameters were determined from a fit of the corresponding line positions in the frame of the effective Hamiltonian (EH) model. A set of selected absolute line intensities was measured and used to derive the parameters of the effective transition moment operator. The exhaustive review of the previous observations gathered with the present results is presented and discussed. It leads to a total number of 3863 energy levels belonging to 21 vibrational states and corresponding to 7315 transitions. In the considered spectral region corresponding to up to 82% of the dissociation energy, the increasing importance of the "dark" states is illustrated by the occurrence of frequent rovibrational perturbations and the observation of many weak lines still unassigned.

Analysis of the Vibration Environment for Airborne Reconnaissance Integrated Electronics System (ARIES) Installed on EP-3E Aircraft

DTIC Science & Technology

1975-04-11

Flight Tests does not definitely confirm those suspicions, but the analysib does indicate that vibration levels measurod at some locations are severe...both the Traveling Wave Tube (TWT) and Feedhorn Coupler exceed the specified sinusoidal qualification levels for these components. d. The TWT is...vibration levels being encountered, then the necessary actions to resolve the discrepancies could be taken. A Lower Rotary Joint returned from the fleet was

The vibrational dependence of dissociative recombination: Rate constants for N{sub 2}{sup +}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guberman, Steven L., E-mail: slg@sci.org

Dissociative recombination rate constants are reported with electron temperature dependent uncertainties for the lowest 5 vibrational levels of the N{sub 2}{sup +} ground state. The rate constants are determined from ab initio calculations of potential curves, electronic widths, quantum defects, and cross sections. At 100 K electron temperature, the rate constants overlap with the exception of the third vibrational level. At and above 300 K, the rate constants for excited vibrational levels are significantly smaller than that for the ground level. It is shown that any experimentally determined total rate constant at 300 K electron temperature that is smaller thanmore » 2.0 × 10{sup −7} cm{sup 3}/s is likely to be for ions that have a substantially excited vibrational population. Using the vibrational level specific rate constants, the total rate constant is in very good agreement with that for an excited vibrational distribution found in a storage ring experiment. It is also shown that a prior analysis of a laser induced fluorescence experiment is quantitatively flawed due to the need to account for reactions with unknown rate constants. Two prior calculations of the dissociative recombination rate constant are shown to be inconsistent with the cross sections upon which they are based. The rate constants calculated here contribute to the resolution of a 30 year old disagreement between modeled and observed N{sub 2}{sup +} ionospheric densities.« less

A quantum-rovibrational-state-selected study of the reaction in the collision energy range of 0.05-10.00 eV: translational, rotational, and vibrational energy effects.

PubMed

Xu, Yuntao; Xiong, Bo; Chang, Yih-Chung; Pan, Yi; Lo, Po Kam; Lau, Kai Chung; Ng, C Y

2017-04-12

We report detailed absolute integral cross sections (σ's) for the quantum-rovibrational-state-selected ion-molecule reaction in the center-of-mass collision energy (E cm ) range of 0.05-10.00 eV, where (vvv) = (000), (100), and (020), and . Three product channels, HCO + + OH, HOCO + + H, and CO + + H 2 O, are identified. The measured σ(HCO + ) curve [σ(HCO + ) versus E cm plot] supports the hypothesis that the formation of the HCO + + OH channel follows an exothermic pathway with no potential energy barriers. Although the HOCO + + H channel is the most exothermic, the σ(HOCO + ) is found to be significantly lower than the σ(HCO + ). The σ(HOCO + ) curve is bimodal, indicating two distinct mechanisms for the formation of HOCO + . The σ(HOCO + ) is strongly inhibited at E cm < 0.4 eV, but is enhanced at E cm > 0.4 eV by (100) vibrational excitation. The E cm onsets of σ(CO + ) determined for the (000) and (100) vibrational states are in excellent agreement with the known thermochemical thresholds. This observation, along with the comparison of the σ(CO + ) curves for the (100) and (000) states, shows that kinetic and vibrational energies are equally effective in promoting the CO + channel. We have also performed high-level ab initio quantum calculations on the potential energy surface, intermediates, and transition state structures for the titled reaction. The calculations reveal potential barriers of ≈0.5-0.6 eV for the formation of HOCO + , and thus account for the low σ(HOCO + ) and its bimodal profile observed. The E cm enhancement for σ(HOCO + ) at E cm ≈ 0.5-5.0 eV can be attributed to the direct collision mechanism, whereas the formation of HOCO + at low E cm < 0.4 eV may involve a complex mechanism, which is mediated by the formation of a loosely sticking complex between HCO + and OH. The direct collision and complex mechanisms proposed also allow the rationalization of the vibrational inhibition at low E cm and the vibrational enhancement at high E cm observed for the σ(HOCO + ).

A model study of assisted adiabatic transfer of population in the presence of collisional dephasing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masuda, Shumpei, E-mail: shumpei.masuda@aalto.fi; Rice, Stuart A., E-mail: s-rice@uchicago.edu

2015-06-28

Previous studies have demonstrated that when experimental conditions generate non-adiabatic dynamics that prevents highly efficient population transfer between states of an isolated system by stimulated Raman adiabatic passage (STIRAP), the addition of an auxiliary counter-diabatic field (CDF) can restore most or all of that efficiency. This paper examines whether that strategy is also successful in a non-isolated system in which the energies of the states fluctuate, e.g., when a solute is subject to collisions with solvent. We study population transfer in two model systems: (i) the three-state system used by Demirplak and Rice [J. Chem. Phys. 116, 8028 (2002)] andmore » (ii) a four-state system, derived from the simulation studies of Demirplak and Rice [J. Chem. Phys. 125, 194517 (2006)], that mimics HCl in liquid Ar. Simulation studies of the vibrational manifold of HCl in dense fluid Ar show that the collision induced vibrational energy level fluctuations have asymmetric distributions. Representations of these asymmetric energy level fluctuation distributions are used in both models (i) and (ii). We identify three sources of degradation of the efficiency of STIRAP generated selective population transfer in model (ii): too small pulse areas of the laser fields, unwanted interference arising from use of strong fields, and the vibrational detuning. For both models (i) and (ii), our examination of the efficiency of STIRAP + CDF population transfer under the influence of the asymmetric distribution of the vibrational energy fluctuations shows that there is a range of field strengths and pulse durations under which STIRAP + CDF control of population transfer has greater efficiency than does STIRAP generated population transfer.« less

Vibrational spectroscopy of NO + (H2O)n: Evidence for the intracluster reaction NO + (H2O)n --> H3O + (H2O)n - 2 (HONO) at n => 4

NASA Astrophysics Data System (ADS)

Choi, Jong-Ho; Kuwata, Keith T.; Haas, Bernd-Michael; Cao, Yibin; Johnson, Matthew S.; Okumura, Mitchio

1994-05-01

Infrared spectra of mass-selected clusters NO+(H2O)n for n=1 to 5 were recorded from 2700 to 3800 cm-1 by vibrational predissociation spectroscopy. Vibrational frequencies and intensities were also calculated for n=1 and 2 at the second-order Møller-Plesset (MP2) level, to aid in the interpretation of the spectra, and at the singles and doubles coupled cluster (CCSD) level energies of n=1 isomers were computed at the MP2 geometries. The smaller clusters (n=1 to 3) were complexes of H2O ligands bound to a nitrosonium ion NO+ core. They possessed perturbed H2O stretch bands and dissociated by loss of H2O. The H2O antisymmetric stretch was absent in n=1 and gradually increased in intensity with n. In the n=4 clusters, we found evidence for the beginning of a second solvation shell as well as the onset of an intracluster reaction that formed HONO. These clusters exhibited additional weak, broad bands between 3200 and 3400 cm-1 and two new minor photodissociation channels, loss of HONO and loss of two H2O molecules. The reaction appeared to go to completion within the n=5 clusters. The primary dissociation channel was loss of HONO, and seven vibrational bands were observed. From an analysis of the spectrum, we concluded that the n=5 cluster rearranged to form H3O+(H2O)3(HONO), i.e., an adduct of the reaction products.

Infrared-Vacuum Ultraviolet Pulsed Field Ionization-Photoelectron Study of C₂H₄ + Using a High-Resolution Infrared Laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xing, Xi; Reed, Beth; Bahng, Mi-Kyung

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The infrared (IR)-vacuum ultraviolet (VUV)-pulsed field ionization-photoelectron (IR-VUV-PFI-PE) spectrum for C₂H₄(X 1A g, V 11 = 1, N' Ka' Kc'=3₀₃) in the VUV range of 83 000-84 800 cm -1 obtained using a single mode infrared laser revealed 24 rotationally resolved vibrational bands for the ion C₂H₄ +(X 2B 3u) ground state. The frequencies and symmetry of the vibrational bandsmore » thus determined, together with the anharmonic frequency predictions calculated at the CCSD(T)/aug-cc-pVQZ level, have allowed the unambiguous assignment of these vibrational bands. These bands are mostly combination bands. The measured frequencies of these bands yield the fundamental frequencies for V 8 + ) 1103± ( 10 cm -1 and V 10 + ) 813 ( 10 cm -1 of C₂H₄ +(X 2B 3u), which have not been determined previously. The present IR-VUV-PFI-PE study also provides truly rovibrationally selected and resolved state-to-state cross sections for the photoionization transitions C₂H₄(X~ 1A g; V 11, N' Ka' Kc') → C₂H₄ +(X ~ 2B 3u; V i +, N + Ka + Kc +), where N' Ka' Kc' denotes the rotational level of C₂H₄(X ~ 1Ag; V 11), and V i + and N + Ka + Kc + represent the vibrational and rotational states of the cation.« less

Skyrme RPA description of γ-vibrational states in rare-earth nuclei

NASA Astrophysics Data System (ADS)

Nesterenko, V. O.; Kartavenko, V. G.; Kleinig, W.; Kvasil, J.; Repko, A.; Jolos, R. V.; Reinhard, P.-G.

2016-01-01

The lowest γ-vibrational states with Kπ = 2+γ in well-deformed Dy, Er and Yb isotopes are investigated within the self-consistent separable quasiparticle random-phase-approximation (QRPA) approach based on the Skyrme functional. The energies Eγ and reduced transition probabilities B(E2)γ of the states are calculated with the Skyrme force SV-mas10. We demonstrate the strong effect of the pairing blocking on the energies of γ-vibrational states. It is also shown that collectivity of γ-vibrational states is strictly determined by keeping the Nilsson selection rules in the corresponding lowest 2qp configurations.

The effect of combined stimulation of external cold and vibration during immunization on pain and anxiety levels in children.

PubMed

Canbulat Şahiner, Nejla; İnal, Sevil; Sevim Akbay, Ayşe

2015-06-01

Procedures involving needles are the most common and major sources of pain in children. External cold and vibration via Buzzy (MMJ Labs, Atlanta, GA) is a method that combines cooling and vibration. This study investigated the effect of the combined stimulation of skin with external cold and vibration via Buzzy on the pain and anxiety levels in children during immunization. This study was a prospective, randomized controlled trial. Children were randomized into two groups: experimental (external cold and Buzzy) and control (no intervention). The pain and anxiety levels of the children were assessed using the Wong-Baker FACES scale and Children Fear Scale. The experimental group showed significantly lower pain and anxiety levels than the control group during immunization. The combined stimulation of skin with external cold and vibration can be used to reduce pain and anxiety during pediatric immunization. Copyright © 2015 American Society of PeriAnesthesia Nurses. Published by Elsevier Inc. All rights reserved.

Vibrational energy flow in photoactive yellow protein revealed by infrared pump-visible probe spectroscopy.

PubMed

Nakamura, Ryosuke; Hamada, Norio

2015-05-14

Vibrational energy flow in the electronic ground state of photoactive yellow protein (PYP) is studied by ultrafast infrared (IR) pump-visible probe spectroscopy. Vibrational modes of the chromophore and the surrounding protein are excited with a femtosecond IR pump pulse, and the subsequent vibrational dynamics in the chromophore are selectively probed with a visible probe pulse through changes in the absorption spectrum of the chromophore. We thus obtain the vibrational energy flow with four characteristic time constants. The vibrational excitation with an IR pulse at 1340, 1420, 1500, or 1670 cm(-1) results in ultrafast intramolecular vibrational redistribution (IVR) with a time constant of 0.2 ps. The vibrational modes excited through the IVR process relax to the initial ground state with a time constant of 6-8 ps in parallel with vibrational cooling with a time constant of 14 ps. In addition, upon excitation with an IR pulse at 1670 cm(-1), we observe the energy flow from the protein backbone to the chromophore that occurs with a time constant of 4.2 ps.

Integrated Advanced Microwave Sounding Unit-A (AMSU-A) METOP Stress Analysis Report (Qual Level Random Vibration) A1 Module

NASA Technical Reports Server (NTRS)

Mehitretter, R.

1996-01-01

Stress analysis of the primary structure of the Meteorological Satellites Project (METSAT) Advanced Microwave Sounding Units-A, A1 Module performed using the Meteorological Operational (METOP) Qualification Level 9.66 grms Random Vibration PSD Spectrum is presented. The random vibration structural margins of safety and natural frequency predictions are summarized.

Effects of mechanical vibration on proliferation and osteogenic differentiation of human periodontal ligament stem cells.

PubMed

Zhang, Chunxiang; Li, Ji; Zhang, Linkun; Zhou, Yi; Hou, Weiwei; Quan, Huixin; Li, Xiaoyu; Chen, Yangxi; Yu, Haiyang

2012-10-01

Paradental tissues (alveolar bone, periodontal ligament (PDL), and gingiva) have the capacity to adapt to their functional environment. The principal cellular elements of the PDL play an important role in normal function, regeneration of periodontal tissue and in orthodontic treatment. Recently, several studies have shown that low-magnitude, high-frequency (LMHF) mechanical vibration can positively influence bone homeostasis; however, the mechanism and optimal conditions for LMHF mechanical vibration have not been elucidated. It has been speculated that LMHF mechanical vibration stimulations have a favourable influence on osteocytes, osteoblasts and their precursors, thereby enhancing the expression of osteoblastic genes involved in bone formation and remodelling. The objective of this study was to test the effect of LMHF mechanical vibration on proliferation and osteogenic differentiation of human PDL stem cells (PDLSCs). Human PDLSCs were isolated from premolar teeth and randomized into vibration (magnitude: 0.3g; frequency: 10-180 Hz; 30 min/24h) and static cultures. The effect of vibration on PDLSC proliferation, differentiation and osteogenic potential was assessed at the genetic and protein level. After LMHF mechanical vibration, PDLSC proliferation was decreased; however, this was accompanied by increased markers of osteogenesis in a frequency-dependent manner. Specifically, alkaline phosphatase activity gradually increased with the frequency of vibration, to a peak at 50 Hz, and the level of osteocalcin was significantly higher than control following vibration at 40 Hz, 50 Hz, 60 Hz, 90 Hz and 120 Hz. Levels of Col-I, Runx2 and Osterix were significantly increased by LMHF mechanical vibration at frequencies of 40 Hz and 50 Hz. Our data demonstrates that LMHF mechanical vibration promotes PDLSC osteogenic differentiation and implies the existence of a frequency-dependent effect of vibration on determining PDLSC commitment to the osteoblast lineage. Copyright © 2012 Elsevier Ltd. All rights reserved.

Hearing with an atympanic ear: good vibration and poor sound-pressure detection in the royal python, Python regius.

PubMed

Christensen, Christian Bech; Christensen-Dalsgaard, Jakob; Brandt, Christian; Madsen, Peter Teglberg

2012-01-15

Snakes lack both an outer ear and a tympanic middle ear, which in most tetrapods provide impedance matching between the air and inner ear fluids and hence improve pressure hearing in air. Snakes would therefore be expected to have very poor pressure hearing and generally be insensitive to airborne sound, whereas the connection of the middle ear bone to the jaw bones in snakes should confer acute sensitivity to substrate vibrations. Some studies have nevertheless claimed that snakes are quite sensitive to both vibration and sound pressure. Here we test the two hypotheses that: (1) snakes are sensitive to sound pressure and (2) snakes are sensitive to vibrations, but cannot hear the sound pressure per se. Vibration and sound-pressure sensitivities were quantified by measuring brainstem evoked potentials in 11 royal pythons, Python regius. Vibrograms and audiograms showed greatest sensitivity at low frequencies of 80-160 Hz, with sensitivities of -54 dB re. 1 m s(-2) and 78 dB re. 20 μPa, respectively. To investigate whether pythons detect sound pressure or sound-induced head vibrations, we measured the sound-induced head vibrations in three dimensions when snakes were exposed to sound pressure at threshold levels. In general, head vibrations induced by threshold-level sound pressure were equal to or greater than those induced by threshold-level vibrations, and therefore sound-pressure sensitivity can be explained by sound-induced head vibration. From this we conclude that pythons, and possibly all snakes, lost effective pressure hearing with the complete reduction of a functional outer and middle ear, but have an acute vibration sensitivity that may be used for communication and detection of predators and prey.

Low‑level mechanical vibration enhances osteoblastogenesis via a canonical Wnt signaling‑associated mechanism.

PubMed

Gao, Heqi; Zhai, Mingming; Wang, Pan; Zhang, Xuhui; Cai, Jing; Chen, Xiaofei; Shen, Guanghao; Luo, Erping; Jing, Da

2017-07-01

Osteoporosis is a skeletal metabolic disease characterized by reduced bone mass and a high susceptibility to fractures, in which osteoblasts and osteoclasts are highly involved in the abnormal bone remodeling processes. Recently, low‑magnitude, high‑frequency whole‑body vibration has been demonstrated to significantly reduce osteopenia experimentally and clinically. However, the underlying mechanism regarding how osteoblastic activity is altered when bone tissues adapt to mechanical vibration remains elusive. The current study systematically investigated the effect and potential molecular signaling mechanisms in mediating the effects of mechanical vibration (0.5 gn, 45 Hz) on primary osteoblasts in vitro. The results of the present study demonstrated that low‑level mechanical stimulation promoted osteoblastic proliferation and extracellular matrix mineralization. In addition, it was also revealed that mechanical vibration induced improved cytoskeleton arrangement in primary osteoblasts. Furthermore, mechanical vibration resulted in significantly increased gene expression of alkaline phosphatase, bone morphogenetic protein 2 and osteoprotegerin, and suppressed sclerostin gene expression, as determined by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analyses. Mechanical vibration was observed to upregulate gene and protein expression levels of osteogenesis‑associated biomarkers, including osteocalcin and Runt‑related transcription factor 2. In addition, RT‑qPCR and western blotting analysis demonstrated that mechanical vibration promoted gene and protein expression of canonical Wnt signaling genes, including Wnt3a, low‑density lipoprotein receptor‑related protein 6 and β‑catenin. In conclusion, the present study demonstrated that mechanical vibration stimulates osteoblastic activities and may function through a potential canonical Wnt signaling‑associated mechanism. These findings provided novel information that improves the understanding of the molecular mechanisms involved in osteoblastic activities in response to mechanical vibration, which may facilitate the scientific application of mechanical vibration for the treatment of osteoporosis in the clinic.

Survey of Active Vibration Isolation Systems for Microgravity Applications

NASA Technical Reports Server (NTRS)

Grodsinsky, Carlos M.; Whorton, Mark S.

2000-01-01

In view of the utility of space vehicles as orbiting science laboratories, the need for vibration isolation systems for acceleration-sensitive experiments has gained increasing visibility. To date, three active microgravity vibration isolation systems have successfully been demonstrated in flight. A tutorial discussion of the microgravity vibration isolation problem, including a description of the acceleration environment of the International Space Station and attenuation requirements, as well as a comparison or the dynamics of passive isolation, active rack-level isolation, and active payload-level isolation is provided. The flight test results of the three demonstrated systems: suppression of transient accelerations by levitation, the microgravity vibration isolation mount, and the active rack isolation system are surveyed.

Internally resonating lattices for bandgap generation and low-frequency vibration control

NASA Astrophysics Data System (ADS)

Baravelli, Emanuele; Ruzzene, Massimo

2013-12-01

The paper reports on a structural concept for high stiffness and high damping performance. A stiff external frame and an internal resonating lattice are combined in a beam-like assembly which is characterized by high frequency bandgaps and tuned vibration attenuation at low frequencies. The resonating lattice consists of an elastomeric material arranged according to a chiral topology which is designed to resonate at selected frequencies. The concept achieves high damping performance by combining the frequency-selective properties of internally resonating structures, with the energy dissipation characteristics of their constituent material. The flexible ligaments, the circular nodes and the non-central interactions of the chiral topology lead to dynamic deformation patterns which are beneficial to energy dissipation. Furthermore, tuning and grading of the elements of the lattice allows for tailoring of the resonating properties so that vibration attenuation is obtained over desired frequency ranges. Numerical and experimental results demonstrate the tuning flexibility of this concept and suggest its potential application for load-carrying structural members parts of vibration and shock prone systems.

Improved Technique for Finding Vibration Parameters

NASA Technical Reports Server (NTRS)

Andrew, L. V.; Park, C. C.

1986-01-01

Filtering and sample manipulation reduce noise effects. Analysis technique improves extraction of vibrational frequencies and damping rates from measurements of vibrations of complicated structure. Structural vibrations measured by accelerometers. Outputs digitized at frequency high enough to cover all modes of interest. Use of method on set of vibrational measurements from Space Shuttle, raised level of coherence from previous values below 50 percent to values between 90 and 99 percent

Dynamics and control of high precision magnetically levitated vibration isolation systems

NASA Technical Reports Server (NTRS)

Youcef-Toumi, K.; Yeh, T-J.

1992-01-01

Vibration control of flexible structures has received a great deal of interest in recent years. Several authors have investigated this topic in the areas of robot manipulators, space structures, and flexible rotors. Key issues associated with the dynamics and control of vibration isolation systems are addressed. Among other important issues to consider in the control of such systems, the location and number of actuators and sensors are essential to effectively control and suppress vibration. We first address the selection of proper actuator and sensor locations leading to a controllable and observable system. The Rayleigh-Ritz modal analysis method is used to develop a lumped-parameter model of a flexible vibration isolation table top. This model is then used to investigate the system's controllability and observability including the coupling effects introduced by the magnetic bearing. This analysis results in necessary and sufficient conditions for proper selection of actuator and sensor locations. These locations are also important for both controller system's complexity and stability of point of views. A favorable pole-zero plot of the open loop transfer functions is presented. Necessary and sufficient conditions for reducing the controller complexity are derived. The results are illustrated by examples using approximate mode shape functions.

Detecting the magnetic response of iron oxide capped organosilane nanostructures using magnetic sample modulation and atomic force microscopy.

PubMed

Li, Jie-Ren; Lewandowski, Brian R; Xu, Song; Garno, Jayne C

2009-06-15

A new imaging strategy using atomic force microscopy (AFM) is demonstrated for mapping magnetic domains at size regimes below 100 nm. The AFM-based imaging mode is referred to as magnetic sample modulation (MSM), since the flux of an AC-generated electromagnetic field is used to induce physical movement of magnetic nanomaterials on surfaces during imaging. The AFM is operated in contact mode using a soft, nonmagnetic tip to detect the physical motion of the sample. By slowly scanning an AFM probe across a vibrating area of the sample, the frequency and amplitude of vibration induced by the magnetic field is tracked by changes in tip deflection. Thus, the AFM tip serves as a force and motion sensor for mapping the vibrational response of magnetic nanomaterials. Essentially, MSM is a hybrid of contact mode AFM combined with selective modulation of magnetic domains. The positional feedback loop for MSM imaging is the same as that used for force modulation and contact mode AFM; however, the vibration of the sample is analyzed using channels of a lock-in amplifier. The investigations are facilitated by nanofabrication methods combining particle lithography with organic vapor deposition and electroless deposition of iron oxide, to prepare designed test platforms of magnetic materials at nanometer length scales. Custom test platforms furnished suitable surfaces for MSM characterizations at the level of individual metal nanostructures.

Molecular structure, vibrational, electronic and thermal properties of 4-vinylcyclohexene by quantum chemical calculations

NASA Astrophysics Data System (ADS)

Nagabalasubramanian, P. B.; Periandy, S.; Karabacak, Mehmet; Govindarajan, M.

2015-06-01

The solid phase FT-IR and FT-Raman spectra of 4-vinylcyclohexene (abbreviated as 4-VCH) have been recorded in the region 4000-100 cm-1. The optimized molecular geometry and vibrational frequencies of the fundamental modes of 4-VCH have been precisely assigned and analyzed with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) method at 6-311++G(d,p) level basis set. The theoretical frequencies were properly scaled and compared with experimentally obtained FT-IR and FT-Raman spectra. Also, the effect due the substitution of vinyl group on the ring vibrational frequencies was analyzed and a detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated total energy distribution (TED). The time dependent DFT (TD-DFT) method was employed to predict its electronic properties, such as electronic transitions by UV-Visible analysis, HOMO and LUMO energies, molecular electrostatic potential (MEP) and various global reactivity and selectivity descriptors (chemical hardness, chemical potential, softness, electrophilicity index). Stability of the molecule arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Atomic charges obtained by Mulliken population analysis and NBO analysis are compared. Thermodynamic properties (heat capacity, entropy and enthalpy) of the title compound at different temperatures are also calculated.

Comparative investigation of vibration and current monitoring for prediction of mechanical and electrical faults in induction motor based on multiclass-support vector machine algorithms

NASA Astrophysics Data System (ADS)

Gangsar, Purushottam; Tiwari, Rajiv

2017-09-01

This paper presents an investigation of vibration and current monitoring for effective fault prediction in induction motor (IM) by using multiclass support vector machine (MSVM) algorithms. Failures of IM may occur due to propagation of a mechanical or electrical fault. Hence, for timely detection of these faults, the vibration as well as current signals was acquired after multiple experiments of varying speeds and external torques from an experimental test rig. Here, total ten different fault conditions that frequently encountered in IM (four mechanical fault, five electrical fault conditions and one no defect condition) have been considered. In the case of stator winding fault, and phase unbalance and single phasing fault, different level of severity were also considered for the prediction. In this study, the identification has been performed of the mechanical and electrical faults, individually and collectively. Fault predictions have been performed using vibration signal alone, current signal alone and vibration-current signal concurrently. The one-versus-one MSVM has been trained at various operating conditions of IM using the radial basis function (RBF) kernel and tested for same conditions, which gives the result in the form of percentage fault prediction. The prediction performance is investigated for the wide range of RBF kernel parameter, i.e. gamma, and selected the best result for one optimal value of gamma for each case. Fault predictions has been performed and investigated for the wide range of operational speeds of the IM as well as external torques on the IM.

Random vibration (stress screening) of printed wiring assemblies

NASA Technical Reports Server (NTRS)

Bastien, Gilbert J.

1988-01-01

The results of a random vibration test screening (RVSS) study of the determination of the upper and lower vibration limits on printed wiring assemblies (PWA) are summarized. The study results are intended to serve as a guide for engineers and designers who make decisions on PWA features that need to withstand the stresses of dynamic testing and screening. The maximum allowable PWA deflection, G levels, and PSD levels are compared to the expected or actual levels to determine if deleterious effects will occur.

The CFVib Experiment: Control of Fluids in Microgravity with Vibrations

NASA Astrophysics Data System (ADS)

Fernandez, J.; Sánchez, P. Salgado; Tinao, I.; Porter, J.; Ezquerro, J. M.

2017-10-01

The Control of Fluids in Microgravity with Vibrations (CFVib) experiment was selected for the 2016 Fly Your Thesis! programme as part of the 65th ESA Parabolic Flight Campaign. The aim of the project is to observe the potentially complex behaviour of vibrated liquids in weightless environments and to investigate the extent to which small-amplitude vibrations can be used to influence and control this behaviour. Piezoelectric materials are used to generate high-frequency vibrations to drive surface waves and large-scale reorientation of the interface. The theory of vibroequilibria, which treats the quasi-stationary surface configurations achieved by this reorientation, was used to predict interesting parameter regimes and interpret fluid behaviour. Here we describe the scientific motivation, objectives, and design of the experiment.

The rotation-vibration structure of the SO 2 C 1B 2 state explained by a new internal coordinate force field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Jun; Park, G. Barratt; Field, Robert W.

A new quartic force field for the SO 2 C ~ 1B 2 state has been derived, based on high resolution data from S 16O 2 and S 18O 2. Included are eight b 2 symmetry vibrational levels of S 16O 2 reported in the first paper of this series [G. B. Park, et al., J. Chem. Phys. 144, 144311 (2016)]. Many of the experimental observables not included in the fit, such as the Franck-Condon intensities and the Coriolis-perturbed effective C rotational constants of highly anharmonic C ~ state vibrational levels, are well reproduced using our force field. Because themore » two stretching modes of the C ~ state are strongly coupled via Fermi-133 interaction, the vibrational structure of the C state is analyzed in a Fermi-system basis set, constructed explicitly in this work via partial diagonalization of the vibrational Hamiltonian. The physical significance of the Fermi-system basis is discussed in terms of semiclassical dynamics, based on study of Fermi-resonance systems by Kellman and coworkers [M. E. Kellman and L. Xiao, J. Chem. Phys. 93, 5821 (1990)]. By diagonalizing the vibrational Hamiltonian in the Fermi-system basis, the vibrational characters of all vibrational levels can be determined unambiguously. It is shown that the bending mode cannot be treated separately from the coupled stretching modes, particularly at vibrational energies of more than 2000 cm –1. Based on our force field, the structure of the Coriolis interactions in the C ~ state of SO 2 is also discussed. As a result, we identify the origin of the alternating patterns in the effective C rotational constants of levels in the vibrational progressions of the symmetry-breaking mode, ν β (which correlates with the antisymmetric stretching mode in our assignment scheme).« less

The rotation-vibration structure of the SO 2 C 1B 2 state explained by a new internal coordinate force field

DOE PAGES

Jiang, Jun; Park, G. Barratt; Field, Robert W.

2016-04-14

A new quartic force field for the SO 2 C ~ 1B 2 state has been derived, based on high resolution data from S 16O 2 and S 18O 2. Included are eight b 2 symmetry vibrational levels of S 16O 2 reported in the first paper of this series [G. B. Park, et al., J. Chem. Phys. 144, 144311 (2016)]. Many of the experimental observables not included in the fit, such as the Franck-Condon intensities and the Coriolis-perturbed effective C rotational constants of highly anharmonic C ~ state vibrational levels, are well reproduced using our force field. Because themore » two stretching modes of the C ~ state are strongly coupled via Fermi-133 interaction, the vibrational structure of the C state is analyzed in a Fermi-system basis set, constructed explicitly in this work via partial diagonalization of the vibrational Hamiltonian. The physical significance of the Fermi-system basis is discussed in terms of semiclassical dynamics, based on study of Fermi-resonance systems by Kellman and coworkers [M. E. Kellman and L. Xiao, J. Chem. Phys. 93, 5821 (1990)]. By diagonalizing the vibrational Hamiltonian in the Fermi-system basis, the vibrational characters of all vibrational levels can be determined unambiguously. It is shown that the bending mode cannot be treated separately from the coupled stretching modes, particularly at vibrational energies of more than 2000 cm –1. Based on our force field, the structure of the Coriolis interactions in the C ~ state of SO 2 is also discussed. As a result, we identify the origin of the alternating patterns in the effective C rotational constants of levels in the vibrational progressions of the symmetry-breaking mode, ν β (which correlates with the antisymmetric stretching mode in our assignment scheme).« less

Self-consistent Non-LTE Model of Infrared Molecular Emissions and Oxygen Dayglows in the Mesosphere and Lower Thermosphere

NASA Technical Reports Server (NTRS)

Feofilov, Artem G.; Yankovsky, Valentine A.; Pesnell, William D.; Kutepov, Alexander A.; Goldberg, Richard A.; Mauilova, Rada O.

2007-01-01

We present the new version of the ALI-ARMS (for Accelerated Lambda Iterations for Atmospheric Radiation and Molecular Spectra) model. The model allows simultaneous self-consistent calculating the non-LTE populations of the electronic-vibrational levels of the O3 and O2 photolysis products and vibrational level populations of CO2, N2,O2, O3, H2O, CO and other molecules with detailed accounting for the variety of the electronic-vibrational, vibrational-vibrational and vibrational-translational energy exchange processes. The model was used as the reference one for modeling the O2 dayglows and infrared molecular emissions for self-consistent diagnostics of the multi-channel space observations of MLT in the SABER experiment It also allows reevaluating the thermalization efficiency of the absorbed solar ultraviolet energy and infrared radiative cooling/heating of MLT by detailed accounting of the electronic-vibrational relaxation of excited photolysis products via the complex chain of collisional energy conversion processes down to the vibrational energy of optically active trace gas molecules.

Measurement of vibrations at different sections of rail through fiber optic sensors

NASA Astrophysics Data System (ADS)

Barreda, A.; Molina-Jiménez, T.; Valero, E.; Recuero, S.

2011-09-01

This paper presents the results of an investigation about how the vibration of railway vehicles affects nearby buildings. The overall objective is to study the vibration generated in urban environments by tram, train and subway, its transmission to the ground and how the buildings and constructions of the environment receive them. Vibrations can generate noise and vibrations in buildings. For this reason it is necessary to characterize the level of vibration affecting rail, road infrastructure and sidewalks and nearby buildings, to assess the influence of the train (speed, type, profile wheel ,..), rail (area of rolling) and route of step, and finally define interim corrective measures. In this study measurements of levels of energy and vibration excitation frequencies will be undertaken through optical techniques: optical fiber networks with distributed Bragg sensors. Measuring these vibrations in different configurations allows us to evaluate the suitability of different sections of rail for different types of uses or environments. This study aims to help improve the safety of the built environment in the vicinity of a railway operation, and thus increase the comfort for passengers and to reduce the environmental impact.

Exposure-response relationships for annoyance due to freight and passenger railway vibration exposure in residential environments.

PubMed

Sharp, Calum; Woodcock, James; Sica, Gennaro; Peris, Eulalia; Moorhouse, Andrew T; Waddington, David C

2014-01-01

In this work, exposure-response relationships for annoyance due to freight and passenger railway vibration exposure in residential environments are developed, so as to better understand the differences in human response to these two sources of environmental vibration. Data for this research come from a field study comprising interviews with respondents and measurements of their vibration exposure (N = 752). A logistic regression model is able to accurately classify 96% of these measured railway vibration signals as freight or passenger based on two signal properties that quantify the duration and low frequency content of each signal. Exposure-response relationships are then determined using ordinal probit modeling with fixed thresholds. The results indicate that people are able to distinguish between freight and passenger railway vibration, and that the annoyance response due to freight railway vibration is significantly higher than that due to passenger railway vibration, even for equal levels of exposure. In terms of a community tolerance level, the population studied is 15 dB (re 10(-6) m s(-2)) more tolerant to passenger railway vibration than freight railway vibration. These results have implications for the expansion of freight traffic on rail, or for policies to promote passenger railway.

Integrating Oil Debris and Vibration Measurements for Intelligent Machine Health Monitoring. Degree awarded by Toledo Univ., May 2002

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.

2003-01-01

A diagnostic tool for detecting damage to gears was developed. Two different measurement technologies, oil debris analysis and vibration were integrated into a health monitoring system for detecting surface fatigue pitting damage on gears. This integrated system showed improved detection and decision-making capabilities as compared to using individual measurement technologies. This diagnostic tool was developed and evaluated experimentally by collecting vibration and oil debris data from fatigue tests performed in the NASA Glenn Spur Gear Fatigue Rig. An oil debris sensor and the two vibration algorithms were adapted as the diagnostic tools. An inductance type oil debris sensor was selected for the oil analysis measurement technology. Gear damage data for this type of sensor was limited to data collected in the NASA Glenn test rigs. For this reason, this analysis included development of a parameter for detecting gear pitting damage using this type of sensor. The vibration data was used to calculate two previously available gear vibration diagnostic algorithms. The two vibration algorithms were selected based on their maturity and published success in detecting damage to gears. Oil debris and vibration features were then developed using fuzzy logic analysis techniques, then input into a multi sensor data fusion process. Results show combining the vibration and oil debris measurement technologies improves the detection of pitting damage on spur gears. As a result of this research, this new diagnostic tool has significantly improved detection of gear damage in the NASA Glenn Spur Gear Fatigue Rigs. This research also resulted in several other findings that will improve the development of future health monitoring systems. Oil debris analysis was found to be more reliable than vibration analysis for detecting pitting fatigue failure of gears and is capable of indicating damage progression. Also, some vibration algorithms are as sensitive to operational effects as they are to damage. Another finding was that clear threshold limits must be established for diagnostic tools. Based on additional experimental data obtained from the NASA Glenn Spiral Bevel Gear Fatigue Rig, the methodology developed in this study can be successfully implemented on other geared systems.

Two-dimensional vibrational-electronic spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.

2015-10-21

Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE)more » to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (ν{sub CN}) and either a ligand-to-metal charge transfer transition ([Fe{sup III}(CN){sub 6}]{sup 3−} dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN){sub 5}Fe{sup II}CNRu{sup III}(NH{sub 3}){sub 5}]{sup −} dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific ν{sub CN} modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a wide range of complex molecular, material, and biological systems.« less

Train-induced field vibration measurements of ground and over-track buildings.

PubMed

Zou, Chao; Wang, Yimin; Moore, James A; Sanayei, Masoud

2017-01-01

Transit-oriented development, such as metro depot and over-track building complexes, has expanded rapidly over the last 5years in China. Over-track building construction has the advantage of comprehensive utilization of land resources, ease of commuting to work, and provide funds for subway construction. But the high frequency of subway operations into and out of the depots can generate excessive vibrations that transmit into the over track buildings, radiate noise within the buildings, hamper the operation of vibration sensitive equipment, and adversely affect the living quality of the building occupants. Field measurements of vibration during subway operations were conducted at Shenzhen, China, a city of 10.62 million people in southern China. Considering the metro depot train testing line and throat area train lines were the main vibration sources, vibration data were captured in five measurement setups. The train-induced vibrations were obtained and compared with limitation of FTA criteria. The structure-radiated noise was calculated using measured vibration levels. The vertical vibration energy directly passed through the columns on both sides of track into the platform, amplifying vibration on the platform by up to 6dB greater than ground levels at testing line area. Vibration amplification around the natural frequency in the vertical direction of over-track building made the peak values of indoor floor vibration about 16dB greater than outdoor platform vibration. We recommend to carefully examining design of new over-track buildings within 40m on the platform over the throat area to avoid excessive vertical vibrations and noise. For both buildings, the measured vertical vibrations were less than the FTA limit. However, it is demonstrated that the traffic-induced high-frequency noise has the potential to annoy occupants on the upper floors. Copyright © 2016 Elsevier B.V. All rights reserved.

Molecular structure and vibrational spectra of three substituted 4-thioflavones by density functional theory and ab initio Hartree-Fock calculations

NASA Astrophysics Data System (ADS)

Li, Xiao-Hong; Liu, Xiang-Ru; Zhang, Xian-Zhou

2011-01-01

The vibrational frequencies of three substituted 4-thioflavones in the ground state have been calculated using the Hartree-Fock and density functional method (B3LYP) with 6-31G* and 6-31+G** basis sets. The structural analysis shows that there exists H-bonding in the selected compounds and the hydrogen bond lengths increase with the augment of the conjugate parameters of the substituent group on the benzene ring. A complete vibrational assignment aided by the theoretical harmonic wavenumber analysis was proposed. The theoretical spectrograms for FT-IR spectra of the title compounds have been constructed. In addition, it is noted that the selected compounds show significant activity against Shigella flexniri. Several electronic properties and thermodynamic parameters were also calculated.

Vibrationally Excited Carbon Monoxide Produced via a Chemical Reaction Between Carbon Vapor and Oxygen

NASA Astrophysics Data System (ADS)

Jans, Elijah R.; Eckert, Zakari; Frederickson, Kraig; Rich, Bill; Adamovich, Igor V.

2017-06-01

Measurements of the vibrational distribution function of carbon monoxide produced via a reaction between carbon vapor and molecular oxygen has shown a total population inversion on vibrational levels 4-7. Carbon vapor, produced using an arc discharge to sublimate graphite, is mixed with an argon oxygen flow. The excited carbon monoxide is vibrationally populated up to level v=14, at low temperatures, T=400-450 K, in a collision-dominated environment, 15-20 Torr, with total population inversions between v=4-7. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of the reaction enthalpy. Kinetic modeling of the flow reactor, including state specific vibrational processes, was performed to infer the vibrational distribution of the products of the reaction. The results show viability of developing of a new chemical CO laser from the reaction of carbon vapor and oxygen.

Theoretical and experimental study of vibration, generated by monorail trains

NASA Astrophysics Data System (ADS)

Rybak, Samuil A.; Makhortykh, Sergey A.; Kostarev, Stanislav A.

2002-11-01

Monorail transport as all other city transport vehicles is the source of high noise and vibration levels. It is less widespread than cars or underground transport but its influence in modern cities enhances. Now in Moscow the first monorail road with trains on tires is designed, therefore the problem of vibration and noise assessments and prediction of its impact on the residential region appears. To assess the levels of generated vibration a physical model of interaction in the system wagon-tire-road coating-viaduct-soil has been proposed and then numerically analyzed. The model is based on the known from publications facts of automobile transport vibration and our own practice concerning underground trains vibration generation. To verify computer simulation results and adjust model parameters the series of measurements of noise and vibration near experimental monorail road was carried out. In the report the results of calculations and measurements will be presented and some outcomes of possible acoustical ecologic situation near monorail roads will be proposed.

Intrusion recognition for optic fiber vibration sensor based on the selective attention mechanism

NASA Astrophysics Data System (ADS)

Xu, Haiyan; Xie, Yingjuan; Li, Min; Zhang, Zhuo; Zhang, Xuewu

2017-11-01

Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. A fiber optic perimeter detection system based on all-fiber interferometric sensor is proposed, through the back-end analysis, processing and intelligent identification, which can distinguish effects of different intrusion activities. In this paper, an intrusion recognition based on the auditory selective attention mechanism is proposed. Firstly, considering the time-frequency of vibration, the spectrogram is calculated. Secondly, imitating the selective attention mechanism, the color, direction and brightness map of the spectrogram is computed. Based on these maps, the feature matrix is formed after normalization. The system could recognize the intrusion activities occurred along the perimeter sensors. Experiment results show that the proposed method for the perimeter is able to differentiate intrusion signals from ambient noises. What's more, the recognition rate of the system is improved while deduced the false alarm rate, the approach is proved by large practical experiment and project.

Development of ride comfort criteria for mass transit systems

NASA Technical Reports Server (NTRS)

Kirby, R. H.; Mikulka, P. J.; Coates, G. D.

1976-01-01

Two studies were conducted on the effects of simultaneous sinusoidal vibration in the vertical and lateral axes on ratings of discomfort in human subjects in a simulated passenger aircraft. In the first experiment each of 24 subjects experienced each of ten levels of vertical frequency in combination with each of ten levels of lateral frequency vibration and rated the discomfort produced on a nine-point, unipolar scale. In the second experiment 72 subjects experienced one of four levels of vertical frequency at each of four levels of vertical amplitude combined with 16 (or 4 x 4) lateral frequency and amplitude conditions. The results of these two studies strongly suggest that there are effects on discomfort that occur when subjects are vibrated in several axes at once that cannot be assessed with research using vibration in only one axis.

Effect of mechanical vibration on transcutaneous oxygen levels in the feet of type 2 diabetes mellitus patients.

PubMed

Rodríguez Reyes, Gerardo; Núñez Carrera, Lidia; Alessi Montero, Aldo; Solís Vivanco, Adriana; Quiñones Uriostegui, Ivett; Pérez Sanpablo, Alberto Isaac

2017-01-06

Foot conditions in patients with diabetes mellitus (DM) are major causes of morbidity and disability. Whole body vibration may promote blood circulation in the lower limbs, hence facilitating perfusion and promoting the supply of nutrients and oxygen to comprised tissues. Transcutaneous oxygen levels (TcPO 2 )>40mmHg in cases of diabetic foot syndrome are associated with a good prognosis in the resolution of ulcers. The objective of this study was to determine whether whole body vibration favors some parameters of interest related to complications associated with the diabetic foot syndrome. Fifty-four patients with DM were included in a 12-week exercise program based on whole body vibration. Glycemic control was determined on the basis of the patients' levels of glycated hemoglobin (HbA 1c ); sensitivity and TcPO 2 levels of each foot were also recorded. Assessments were performed prior to initiating the whole body vibration program and at the end of it. No significant changes were observed in the patients' HbA 1c (P=.442) levels or sensitivity (P=.07). A significant 7mmHg increase (P<.0001; effect size: d=0.53) was observed in the concentration of TcPO 2 . Whole body vibration may increase TcPO 2 levels with useful implications for the prevention or management of complications associated with restricted blood perfusion in the diabetic foot syndrome. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

Near-Infrared Spectroscopy of Small Protonated Water Clusters

NASA Astrophysics Data System (ADS)

Wagner, J. Philipp; McDonald, David C., II; McCoy, Anne B.; Duncan, Michael A.

2017-06-01

Small protonated water clusters and their argon tagged analogues of the general formula H^{+}(H_{2}O)_{n}Ar_{m} have been generated in a pulsed electric discharge source. Clusters containing n=1-8 water molecules were mass-selected and their absorptions in the near-infrared were probed with a tunable Nd/colonYAG pumped OPA/OPA laser system in the region from 4850-7350 cm^{-1}. A doublet corresponding to overtones of the free O-H stretches of the external waters was observed around 7200 cm^{-1} that was continuously decreasing in intensity with increasing cluster size. Broad, mostly featureless absorptions were found around 5300 cm^{-1} associated with stretch/bend combinations and with the hydrogen bonded waters in the core of the clusters. Vibrational assignments were substantiated by comparison to anharmonic frequency computations via second-order vibrational perturbation theory (VPT2) at the MP2/aug-cc-pVTZ level of theory.

Thermally and vibrationally induced conformational isomerizations, infrared spectra, and photochemistry of gallic acid in low-temperature matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Justino, Licínia L. G., E-mail: liciniaj@ci.uc.pt; Reva, Igor; Fausto, Rui

2016-07-07

Near-infrared (near-IR) narrowband selective vibrational excitation and annealing of gallic acid (3,4,5-trihydroxybenzoic acid) isolated in cryogenic matrices were used to induce interconversions between its most stable conformers. The isomerizations were probed by infrared spectroscopy. An extensive set of quantum chemical calculations, carried out at the DFT(B3LYP)/6-311++G(d,p) level of approximation, was used to undertake a detailed analysis of the ground state potential energy surface of the molecule. This investigation of the molecule conformational space allowed extracting mechanistic insights into the observed annealing- or near-IR-induced isomerization processes. The infrared spectra of the two most stable conformers of gallic acid in N{sub 2},more » Xe, and Ar matrices were fully assigned. Finally, the UV-induced photochemistry of the matrix isolated compound was investigated.« less

The Soleil View on Prototypical Organic Nitriles: Selected Vibrational Modes of Ethyl Cyanide, C_2H_5CN, and Spectroscopic Analysis Using AN Automated Spectral Assignment Procedure (asap)

NASA Astrophysics Data System (ADS)

Endres, Christian; Caselli, Paola; Martin-Drumel, Marie-Aline; McCarthy, Michael C.; Pirali, Olivier; Wehres, Nadine; Schlemmer, Stephan; Thorwirth, Sven

2016-06-01

Vibrational spectra of small organic nitriles, propionitrile and n-butyronitrile, have been investigated at high spectral resolution at the French national synchroton facility SOLEIL using Fourier-transform far-infrared spectroscopy (< 700 cm-1). The Automated Spectral Assignment Procedure (ASAP) has been used for line assignement and accurate determination of rotational level energies, in particular, of the ν20=1 and the ν12=1 states of propionitrile. The analysis does not only confirm the applicability of the ASAP in the treatment of (dense) high-resolution infrared spectra but also reveals some of its limitations which will be discussed in some detail. M. A. Martin-Drumel, C. P. Endres, O. Zingsheim, T. Salomon, J. van Wijngaarden, O. Pirali, S. Gruet, F. Lewen, S. Schlemmer, M. C. McCarthy, and S. Thorwirth 2015, J. Mol. Spectrosc. 315, 72

Comparison of high‐intensity sound and mechanical vibration for cleaning porous titanium cylinders fabricated using selective laser melting

PubMed Central

Seiffert, Gary; Sutcliffe, Chris

2015-01-01

Abstract Orthopedic components, such as the acetabular cup in total hip joint replacement, can be fabricated using porous metals, such as titanium, and a number of processes, such as selective laser melting. The issue of how to effectively remove loose powder from the pores (residual powder) of such components has not been addressed in the literature. In this work, we investigated the feasibility of two processes, acoustic cleaning using high‐intensity sound inside acoustic horns and mechanical vibration, to remove residual titanium powder from selective laser melting‐fabricated cylinders. With acoustic cleaning, the amount of residual powder removed was not influenced by either the fundamental frequency of the horn used (75 vs. 230 Hz) or, for a given horn, the number of soundings (between 1 and 20). With mechanical vibration, the amount of residual powder removed was not influenced by the application time (10 vs. 20 s). Acoustic cleaning was found to be more reliable and effective in removal of residual powder than cleaning with mechanical vibration. It is concluded that acoustic cleaning using high‐intensity sound has significant potential for use in the final preparation stages of porous metal orthopedic components. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 117–123, 2017. PMID:26426906

Characterization of Train-Induced Vibration and its Effect on Fecal Corticosterone Metabolites in Mice

PubMed Central

Atanasov, Nicholas A; Sargent, Jennifer L; Parmigiani, John P; Palme, Rupert; Diggs, Helen E

2015-01-01

Excessive environmental vibrations can have deleterious effects on animal health and experimental results, but they remain poorly understood in the animal laboratory setting. The aims of this study were to characterize train-associated vibration in a rodent vivarium and to assess the effects of this vibration on the reproductive success and fecal corticosterone metabolite levels of mice. An instrumented cage, featuring a high-sensitivity microphone and accelerometer, was used to characterize the vibrations and sound in a vivarium that is near an active railroad. The vibrations caused by the passing trains are 3 times larger in amplitude than are the ambient facility vibrations, whereas most of the associated sound was below the audible range for mice. Mice housed in the room closest to the railroad tracks had pregnancy rates that were 50% to 60% lower than those of mice of the same strains but bred in other parts of the facility. To verify the effect of the train vibrations, we used a custom-built electromagnetic shaker to simulate the train-induced vibrations in a controlled environment. Fecal pellets were collected from male and female mice that were exposed to the simulated vibrations and from unexposed control animals. Analysis of the fecal samples revealed that vibrations similar to those produced by a passing train can increase the levels of fecal corticosterone metabolites in female mice. These increases warrant attention to the effects of vibration on mice and, consequently, on reproduction and experimental outcomes. PMID:26632783

Characterization of Train-Induced Vibration and its Effect on Fecal Corticosterone Metabolites in Mice.

PubMed

Atanasov, Nicholas A; Sargent, Jennifer L; Parmigiani, John P; Palme, Rupert; Diggs, Helen E

2015-11-01

Excessive environmental vibrations can have deleterious effects on animal health and experimental results, but they remain poorly understood in the animal laboratory setting. The aims of this study were to characterize train-associated vibration in a rodent vivarium and to assess the effects of this vibration on the reproductive success and fecal corticosterone metabolite levels of mice. An instrumented cage, featuring a high-sensitivity microphone and accelerometer, was used to characterize the vibrations and sound in a vivarium that is near an active railroad. The vibrations caused by the passing trains are 3 times larger in amplitude than are the ambient facility vibrations, whereas most of the associated sound was below the audible range for mice. Mice housed in the room closest to the railroad tracks had pregnancy rates that were 50% to 60% lower than those of mice of the same strains but bred in other parts of the facility. To verify the effect of the train vibrations, we used a custom-built electromagnetic shaker to simulate the train-induced vibrations in a controlled environment. Fecal pellets were collected from male and female mice that were exposed to the simulated vibrations and from unexposed control animals. Analysis of the fecal samples revealed that vibrations similar to those produced by a passing train can increase the levels of fecal corticosterone metabolites in female mice. These increases warrant attention to the effects of vibration on mice and, consequently, on reproduction and experimental outcomes.

A Survey of Active Vibration Isolation Systems for Microgravity Applications

NASA Technical Reports Server (NTRS)

Grodsinsky, Carlos M.; Whorton, Mark S.

2000-01-01

In view of the utility of space vehicles as orbiting science laboratories, the need for vibration isolation systems for acceleration sensitive experiments has gained increasing visibility. To date, three active microgravity vibration isolation systems have successfully been demonstrated in flight. This paper provides a tutorial discussion of the microgravity vibration isolation problem including a description of the acceleration environment of the International Space Station and attenuation requirements as well as a comparison of the dynamics of passive isolation, active rack-level isolation, and active payload-level isolation. This paper also surveys the flight test results of the three demonstrated systems: Suppression of Transient Accelerations By Levitation (STABLE); the Microgravity Vibration Isolation Mount (MIM); and the Active Rack Isolation System (ARIS).

Characterization of Friction Joints Subjected to High Levels of Random Vibration

NASA Technical Reports Server (NTRS)

deSantos, Omar; MacNeal, Paul

2012-01-01

This paper describes the test program in detail including test sample description, test procedures, and vibration test results of multiple test samples. The material pairs used in the experiment were Aluminum-Aluminum, Aluminum- Dicronite coated Aluminum, and Aluminum-Plasmadize coated Aluminum. Levels of vibration for each set of twelve samples of each material pairing were gradually increased until all samples experienced substantial displacement. Data was collected on 1) acceleration in all three axes, 2) relative static displacement between vibration runs utilizing photogrammetry techniques, and 3) surface galling and contaminant generation. This data was used to estimate the values of static friction during random vibratory motion when "stick-slip" occurs and compare these to static friction coefficients measured before and after vibration testing.

Impact-based piezoelectric energy harvester for multidimensional, low-level, broadband, and low-frequency vibrations

NASA Astrophysics Data System (ADS)

Zhang, Hongjiang; Jiang, Senlin; He, Xuefeng

2017-05-01

This letter proposes an impact-based piezoelectric energy harvester that uses a rolling bead contained in a bracket that is supported by a spring. Under either translational or rotational base excitation, the bead moves within the bracket and collides with piezoelectric cantilevers that are located around the bracket; these collisions cause the piezoelectric beams to vibrate and thus produce electrical outputs. The low rolling friction and the motion amplification effect of the spring make the resulting device suitable for collection of low-level vibration energy. Experiments show that the proposed harvester is promising for use in scavenging of energy from the multidimensional, low-level, broadband, and low-frequency vibrations that occur in natural environments.

Design of a Long-Stroke Noncontact Electromagnetic Actuator for Active Vibration Isolation

NASA Technical Reports Server (NTRS)

Banerjee, Bibhuti; Allaire, Paul E.

1996-01-01

A long-stroke moving coil Lorentz Actuator was designed for use in a microgravity vibration isolation experiment. The final design had a stroke of 5.08 cm (2 in) and enough force capability to isolate a mass of the order of 22.7-45.4 kg. A simple dynamic magnetic circuit analysis, using an electrical analog, was developed for the initial design of the actuator. A neodymium-iron-boron material with energy density of 278 T-kA/m (35 MGOe) was selected to supply the magnetic field. The effect of changes in the design parameters of core diameter, shell outer diameter, pole face length, and coil wire layers were investigated. An extensive three-dimensional finite element analysis was carried out to accurately determine linearity with regard to axial position of the coil and coil current levels. The actuator was constructed and tested on a universal testing machine. Example plots are shown, indicating good linearity over the stroke of approximately 5.08 cm (2 in) and a range of coil currents from -1.5 A to +1.5 A. The actuator was then used for the microgravity vibration isolation experiments, described elsewhere.

Differences between mechanical and neural tuning at the apex of the intact guinea pig cochlea

NASA Astrophysics Data System (ADS)

Recio-Spinoso, Alberto; Oghalai, John S.

2018-05-01

While most of human speech information is contained within frequencies < 3-4 kHz, only a few mechanical measurements have been made in cochlear regions responsive to such low frequencies. Furthermore, the data that do exist are difficult to interpret given the technical difficulties in performing the experiments and/or the artifacts that result from opening the otic capsule bone to visualize the organ of Corti. Here, we overcame historical technical limitations and non-invasively measured sound-induced vibrations within the apex of the guinea pig cochlea using volumetric optical coherence tomography vibrometry (VOCTV). We found that vibrations within apical cochlear regions, with neural tuning below 2 kHz, demonstrate low-pass filter characteristics. There was evidence of a low-level of broad-band cochlear amplification that did not sharpen frequency selectivity. We compared the vibratory responses we measured to previously-measured single-unit auditory nerve tuning curves in the same frequency range, and found that mechanical responses do not match neural responses. These data suggest that, for low frequency cochlear regions, inner hair cells not only transduce vibrations of the organ of Corti but also sharpen frequency tuning.

Gerotor and bearing system for whirling mass orbital vibrator

DOEpatents

Brett, James Ford; Westermark, Robert Victor; Turner, Jr., Joey Earl; Lovin, Samuel Scott; Cole, Jack Howard; Myers, Will

2007-02-27

A gerotor and bearing apparatus for a whirling mass orbital vibrator which generates vibration in a borehole. The apparatus includes a gerotor with an inner gear rotated by a shaft having one less lobe than an outer gear. A whirling mass is attached to the shaft. At least one bearing is attached to the shaft so that the bearing engages at least one sleeve. A mechanism is provided to rotate the inner gear, the mass and the bearing in a selected rotational direction in order to cause the mass, the inner gear, and the bearing to backwards whirl in an opposite rotational direction. The backwards whirling mass creates seismic vibrations.

Comparison of wavelet based denoising schemes for gear condition monitoring: An Artificial Neural Network based Approach

NASA Astrophysics Data System (ADS)

Ahmed, Rounaq; Srinivasa Pai, P.; Sriram, N. S.; Bhat, Vasudeva

2018-02-01

Vibration Analysis has been extensively used in recent past for gear fault diagnosis. The vibration signals extracted is usually contaminated with noise and may lead to wrong interpretation of results. The denoising of extracted vibration signals helps the fault diagnosis by giving meaningful results. Wavelet Transform (WT) increases signal to noise ratio (SNR), reduces root mean square error (RMSE) and is effective to denoise the gear vibration signals. The extracted signals have to be denoised by selecting a proper denoising scheme in order to prevent the loss of signal information along with noise. An approach has been made in this work to show the effectiveness of Principal Component Analysis (PCA) to denoise gear vibration signal. In this regard three selected wavelet based denoising schemes namely PCA, Empirical Mode Decomposition (EMD), Neighcoeff Coefficient (NC), has been compared with Adaptive Threshold (AT) an extensively used wavelet based denoising scheme for gear vibration signal. The vibration signals acquired from a customized gear test rig were denoised by above mentioned four denoising schemes. The fault identification capability as well as SNR, Kurtosis and RMSE for the four denoising schemes have been compared. Features extracted from the denoised signals have been used to train and test artificial neural network (ANN) models. The performances of the four denoising schemes have been evaluated based on the performance of the ANN models. The best denoising scheme has been identified, based on the classification accuracy results. PCA is effective in all the regards as a best denoising scheme.

The influence of vibrational state-resolved transport coefficients on the wave propagation in diatomic gases

NASA Astrophysics Data System (ADS)

Kremer, Gilberto M.; Kunova, Olga V.; Kustova, Elena V.; Oblapenko, George P.

2018-01-01

A detailed kinetic-theory model for the vibrationally state-resolved transport coefficients is developed taking into account the dependence of the collision cross section on the size of vibrationally excited molecule. Algorithms for the calculation of shear and bulk viscosity, thermal conductivity, thermal diffusion and diffusion coefficients for vibrational states are proposed. The transport coefficients are evaluated for single-component diatomic gases N2, O2, NO, H2, Cl2 in the wide range of temperature, and the effects of molecular diameters and the number of accounted states are discussed. The developed model is applied to study wave propagation in diatomic gases. For the case of initial Boltzmann distribution, the influence of vibrational excitation on the phase velocity and attenuation coefficient is found to be weak. We expect more significant effect in the case of initial thermal non-equilibrium, for instance in gases with optically pumped selected vibrational states.

Active Outer Hair Cells Affect the Sound-Evoked Vibration of the Reticular Lamina

NASA Astrophysics Data System (ADS)

Jacob, Stefan; Fridberger, Anders

2011-11-01

It is well established that the organ of Corti uses active mechanisms to enhance its sensitivity and frequency selectivity. Two possible mechanisms have been identified, both capable of producing mechanical forces, which can alter the sound-evoked vibration of the hearing organ. However, little is known about the effect of these forces on the sound-evoked vibration pattern of the reticular lamina. Current injections into scala media were used to alter the amplitude of the active mechanisms in the apex of the guinea pig temporal bone. We used time-resolved confocal imaging to access the vibration pattern of individual outer hair cells. During positive current injection the the sound-evoked vibration of outer hair cell row three increased while row one showed a small decrease. Negative currents reversed the observed effect. We conclude that the outer hair cell mediated modification of reticular lamina vibration patterns could contribute to the inner hair cell stimulation.

Floor vibration evaluations for medical facilities

NASA Astrophysics Data System (ADS)

Himmel, Chad N.

2003-10-01

The structural floor design for new medical facilities is often selected early in the design phase and in renovation projects, the floor structure already exists. Because the floor structure can often have an influence on the location of vibration sensitive medical equipment and facilities, it is becoming necessary to identify the best locations for equipment and facilities early in the design process. Even though specific criteria for vibration-sensitive uses and equipment may not always be available early in the design phase, it should be possible to determine compatible floor structures for planned vibration-sensitive uses by comparing conceptual layouts with generic floor vibration criteria. Relatively simple evaluations of planned uses and generic criteria, combined with on-site vibration and noise measurements early in design phase, can significantly reduce future design problems and expense. Concepts of evaluation procedures and analyses will be presented in this paper. Generic floor vibration criteria and appropriate parameters to control resonant floor vibration and noise will be discussed for typical medical facilities and medical research facilities. Physical, economic, and logistical limitations that affect implementation will be discussed through case studies.

POTENTIAL EFFECTS OF WHOLE-BODY VIBRATION EXERCISES ON BLOOD FLOW KINETICS OF DIFFERENT POPULATIONS: A SYSTEMATIC REVIEW WITH A SUITABLE APPROACH

PubMed Central

Sá-Caputo, Danúbia; Paineiras-Domingos, Laisa; Carvalho-Lima, Rafaelle; Dias-Costa, Glenda; de Paiva, Patrícia de Castro; de Azeredo, Claudia Figueiredo; Carmo, Roberto Carlos Resende; Dionello, Carla F.; Moreira-Marconi, Eloá; Frederico, Éric Heleno F.F.; Sousa-Gonçalves, Cintia Renata; Morel, Danielle S.; Paiva, Dulciane N.; Avelar, Núbia C.P.; Lacerda, Ana C.; Magalhães, Carlos E.V.; Castro, Leonardo S.; Presta, Giuseppe A.; de Paoli, Severo; Sañudo, Borja; Bernardo-Filho, Mario

2017-01-01

Background: The ability to control skin blood flow decreases with advancing age and some clinical disorders, as in diabetes and in rheumatologic diseases. Feasible clinical strategies such as whole-body vibration exercise (WBVE) are being used without a clear understanding of its effects. The aim of the present study is to review the effects of the WBVE on blood flow kinetics and its feasibility in different populations. Material and Methods: The level of evidence (LE) of selected papers in PubMed and/or PEDRo databases was determined. We selected randomized, controlled trials in English to be evaluated. Results: Six studies had LE II, one had LE III-2 and one III-3 according to the NHMRC. A great variability among the protocols was observed but also in the assessment devices; therefore, more research about this topic is warranted. Conclusion: Despite the limitations, it is can be concluded that the use of WBVE has proven to be a safe and useful strategy to improve blood flow. However, more studies with greater methodological quality are needed to clearly define the more suitable protocols. PMID:28740943

Effect of whole body vibration training on lower limb performance in selected high-level ballet students.

PubMed

Annino, Giuseppe; Padua, Elvira; Castagna, Carlo; Di Salvo, Valter; Minichella, Stefano; Tsarpela, Olga; Manzi, Vincenzo; D'Ottavio, Stefano

2007-11-01

The aim of this study was to examine the effects of 8 weeks of whole body vibration (WBV) training on vertical jump ability (CMJ) and knee-extensor performance at selected external loads (50, 70, and 100 kg; leg-press exercise) in elite ballerinas. Twenty-two (age, 21.25 +/- 1.5 years) full-time ballerinas were assigned randomly to the experimental (E, n = 11) and control (C, n = 11) groups. The experimental group was submitted to WBV training 3 times per week before ballet practice. During the training period, the E and C groups undertook the same amount of ballet practice. Posttraining CMJ performance significantly increased in E group (6.3 +/- 3.8%, p < 0.001). Furthermore, E group showed significant (p < 0.05-0.001) posttraining average leg-press power and velocity improvements at all the external loads considered. Consequently, the force-velocity and power-velocity relationship shifted to the right after WBV training in the E group. The results of the present study show that WBV training is an effective short-term training methodology for inducing improvements in knee-extensor explosiveness in elite ballerinas.

Vibration isolation and pressure compensation apparatus for sensitive instrumentation

NASA Technical Reports Server (NTRS)

Averill, R. D. (Inventor)

1983-01-01

A system for attenuating the inherent vibration associated with a mechanical refrigeration unit employed to cryogenically cool sensitive instruments used in measuring chemical constituents of the atmosphere is described. A modular system including an instrument housing and a reaction bracket with a refrigerator unit floated there between comprise the instrumentation system. A pair of evacuated bellows that "float' refrigerator unit and provide pressure compensation at all levels of pressure from seal level to the vacuum of space. Vibration isolators and when needed provide additional vibration damping for the refrigerator unit. A flexible thermal strap (20 K) serves to provide essentially vibration free thermal contact between cold tip of the refrigerator unit and the instrument component mounted on the IDL mount. Another flexible strap (77 K) serves to provide vibration free thermal contact between the TDL mount thermal shroud and a thermal shroud disposed about the thermal shaft.

A global ab initio potential for HCN/HNC, exact vibrational energies, and comparison to experiment

NASA Technical Reports Server (NTRS)

Bentley, Joseph A.; Bowman, Joel M.; Gazdy, Bela; Lee, Timothy J.; Dateo, Christopher E.

1992-01-01

An ab initio (i.e., from first principles) calculation of vibrational energies of HCN and HNC is reported. The vibrational calculations were done with a new potential derived from a fit to 1124 ab initio electronic energies which were calculated using the highly accurate CCSD(T) coupled-cluster method in conjunction with a large atomic natural orbital basis set. The properties of this potential are presented, and the vibrational calculations are compared to experiment for 54 vibrational transitions, 39 of which are for zero total angular momentum, J = 0, and 15 of which are for J = 1. The level of agreement with experiment is unprecedented for a triatomic with two nonhydrogen atoms, and demonstrates the capability of the latest computational methods to give reliable predictions on a strongly bound triatomic molecule at very high levels of vibrational excitation.

[Hand-arm vibration syndrome in a nurse carrying out gypsum cutting operations].

PubMed

Speziale, Martina; Picchiotti, E

2009-01-01

A professional nurse, employed mainly on gypsum cutting operations, developed a hand-arm vibration syndrome with Raynaud's phenomenon, neurosensitive disorders and impairment of the bone and joints apparatus of the hand and arm. The nurse underwent diagnostic investigations (cold test, X-ray of the upper limbs, blood tests); also the vibration levels transmitted from instrument were measured and the exposure times were established. Clinical investigations showed the presence of a hand-arm vibration syndrome with secondary Raynaud's phenomenon and environmental surveys revealed very high vibration levels, such as could be associated with the disease with a causal relationship. In the literature no reports exist of the vibration syndrome being associated with health care workers in orthopaedic departments. The case described in this study occurred because of peculiar organisational factors that most likely have never occurred in other hospitals or orthopaedic departments.

[Complaints of low back pain among private farmers exposed to whole body vibration].

PubMed

Solecki, Leszek

2014-01-01

Work-related lower back disorders, which involve the lumbo-sacral region, as well as injuries of the lumbar section of the spine, are a serious and constantly growing problem in Europe. Whole body vibration is one of the major hazardous factors suspected of the development of back pain. The study covered a selected group of males, 98 farmers (aged 55.3 +/- 10.1) from the area of 7 communes in the Lublin Region, engaged in the mixed agricultural production (plant-animal). The control group consisted of 40 academic workers (university and research institute employees) aged 48.9 +/- 9.6 years. A questionnaire concerning low back pain (in the lumbar region) designed by the researchers of the Institute of Rural Health in Lublin was used as a major research tool. The degree of farmers' exposure to whole body vibration was evaluated based on the parameter known as a cumulative vibration dose (d) (years x m2 x s(-1)). The measurements showed that the cumulative vibration dose for the selected group of farmers (98) remained within the range of 2.90-9.68 (years x m2 x s(-1)), in the time interval between 15-50 years of work in conditions of exposure to vibration. The survey confirmed that private farmers exposed to whole body vibration considerably more frequently complained of back pain (92 farmers, 94% of the total number of respondents), than academic workers (control group not exposed to whole body vibration (25 researchers, 63%); p < 0.0001. Also the frequency of back pain in all the three time intervals of employment (15-25, 26-35, 36-50 years) is significantly higher in the group of farmers than in the control group (p < 0.05). The frequency of back pains experienced by farmers during the entire period of occupational activity increases with a growing dose of whole body vibration (p = 0.005). In the incidence of chronic pain an upward tendency was observed (statistically insignificant).

Short-range photoassociation of LiRb

NASA Astrophysics Data System (ADS)

Blasing, David; Stevenson, Ian; Pérez-Ríos, Jesús; Elliott, Daniel; Chen, Yong

2017-04-01

We have observed short-range photoassociation of 7Li85Rb to the two lowest vibrational states of the d3 Π potential. We have also observed several a3Σ+ vibrational levels with generation rates between 102 and 103 molecules per second, resulting from the spontaneous decay of these d3 Π molecules. This is the first observation of many of these a3Σ+ levels. We observe an alternation of the peak heights in the rotational photoassociation spectrum that depends on the parity of the excited molecular state. Franck-Condon overlap calculations predict that photoassociation to higher vibrational levels of the d3 Π , in particular the sixth vibrational level, should populate the lowest vibrational level of the a3Σ+ state with a rate as high as 104 molecules per second. This work also motivates an experimental search for short-range photoassociation to other bound molecules, such as the c3Σ+ or b3 Π , as prospects for preparing ground-state molecules. The experimental work was funded by the Purdue Office of the Vice President for Research AMO Incentive Grant 206732 and J.P.-R. acknowledges support from NSF Grant No. PHY-130690.

International Workshop on Vibration Isolation Technology for Microgravity Science Applications

NASA Technical Reports Server (NTRS)

Lubomski, Joseph F. (Editor)

1992-01-01

The International Workshop on Vibration Isolation Technology for Microgravity Science Applications was held on April 23-25, 1991 at the Holiday Inn in Middleburg Heights, Ohio. The main objective of the conference was to explore vibration isolation requirements of space experiments and what level of vibration isolation could be provided both by present and planned systems on the Space Shuttle and Space Station Freedom and by state of the art vibration isolation technology.

The efficiency evaluation of support vibration isolation with mechanic inertial motion converter for vibroactive process equipment

NASA Astrophysics Data System (ADS)

Buryan, Yu. A.; Babichev, D. O.; Silkov, M. V.; Shtripling, L. O.; Kalashnikov, B. A.

2017-08-01

This research refers to the problems of processing equipment protection from vibration influence. The theory issues of vibration isolation for vibroactive objects such as engines, pumps, compressors, fans, piping, etc. are considered. The design of the perspective air spring with the parallel mounted mechanical inertial motion converter is offered. The mathematical model of the suspension, allowing selecting options to reduce the factor of the force transmission to the base in a certain frequency range is obtained.

Flight and Analytical Methods for Determining the Coupled Vibration Response of Tandem Helicopters

NASA Technical Reports Server (NTRS)

Yeates, John E , Jr; Brooks, George W; Houbolt, John C

1957-01-01

Chapter one presents a discussion of flight-test and analysis methods for some selected helicopter vibration studies. The use of a mechanical shaker in flight to determine the structural response is reported. A method for the analytical determination of the natural coupled frequencies and mode shapes of vibrations in the vertical plane of tandem helicopters is presented in Chapter two. The coupled mode shapes and frequencies are then used to calculate the response of the helicopter to applied oscillating forces.

Actively Controlled Magnetic Vibration-Isolation System

NASA Technical Reports Server (NTRS)

Grodsinky, Carlos M.; Logsdon, Kirk A.; Wbomski, Joseph F.; Brown, Gerald V.

1993-01-01

Prototype magnetic suspension system with active control isolates object from vibrations in all six degrees of freedom at frequencies as low as 0.01 Hz. Designed specifically to protect instruments aboard spacecraft by suppressing vibrations to microgravity levels; basic control approach used for such terrestrial uses as suppression of shocks and other vibrations in trucks and railroad cars.

Relationship between hand-arm vibration exposure and onset time for symptoms in a heavy engineering production workshop.

PubMed

Burström, Lage; Hagberg, Mats; Lundström, Ronnie; Nilsson, Tohr

2006-06-01

This study examined onset time for reported vascular and neurological symptoms in relation to the vibration load in a group of workers exposed to vibration. Information on the self-stated year for the first occurrence of symptoms was collected by means of questionnaires. During interviews data were obtained on self-stated estimations of daily exposure time, type of tool, and number of months or years with different exposures. The estimations of the vibration magnitudes of exposure were based on conducted measurements. From these data, the individual vibration exposure at the time of onset of symptoms was calculated. The incidence was 25.6 and 32.9 per 1000 exposure years for vascular and neurological symptoms, respectively, in the group of workers. The first onset of symptoms appeared after an average of 12 years of exposure. For the workers, the symptoms of vascular or neurological disorders started after about the same number of exposure years. The calculated accumulated acceleration correlated best with the onset time of symptoms. It was concluded that, since the workers' exposure to vibration was below the action level established in the European vibration directive, the results suggest that the action level is not a safe level for avoiding vascular and neurological symptoms.

Selective vibrational excitation of the ethylene--fluorine reaction in a nitrogen matrix. II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frei, H.

1983-07-15

The product branching between 1,2-difluoroethane and vinyl fluoride (plus HF) of the selective vibrationally stimulated reaction of molecular fluorine with C/sub 2/H/sub 4/ has been studied in a nitrogen matrix at 12 K and found to be the same for five different vibrational transitions of C/sub 2/H/sub 4/ between 1896 and 4209 cm/sup -1/. The HF/DF branching ratio of the reaction of F/sub 2/ with CH/sub 2/CD/sub 2/, trans-CHDCHD, and cis-CHDCHD was determined to be 1.1, independent of precursor C/sub 2/H/sub 2/D/sub 2/ isomer and particular mode which excited the reaction. These results, as well as the analysis of themore » mixtures of partially deuterated vinyl fluoride molecules produced by each C/sub 2/H/sub 2/D/sub 2/ isomer indicate that the product branching occurs by ..cap alpha beta.. elimination of HF(DF) from a vibrationally excited, electronic ground state 1,2-difluoroethane intermediate. Selective vibrational excitation of fluorine reactions in isotopically mixed matrices t-CHDCHD/C/sub 2/H/sub 4//F/sub 2//N/sub 2/ and CH/sub 2/CD/sub 2//C/sub 2/H/sub 4//F/sub 2//N/sub 2/, and in matrices C/sub 2/H/sub 2//C/sub 2/H/sub 4//F/sub 2//N/sub 2/ revealed a high degree of isotopic and molecular selectivity. The extent to which intermolecular energy transfer occurred is qualitatively explained in terms of dipole coupled vibrational energy transfer. A study of the loss of absorbance of the C/sub 2/H/sub 4/ x F/sub 2/ pairs in case of ..nu../sub 9/ as a function of both the laser irradiation frequency within the absorption profile, and the ethylene concentration showed that the C/sub 2/H/sub 4/ x F/sub 2/ absorption is inhomogeneously broadened. Substantial depletion of reactive pairs which did not absorb laser light is interpreted in terms of Forster transfer.« less

System precisely controls oscillation of vibrating mass

NASA Technical Reports Server (NTRS)

Hancock, D. J.

1967-01-01

System precisely controls the sinusoidal amplitude of a vibrating mechanical mass. Using two sets of coils, the system regulates the drive signal amplitude at the precise level to maintain the mechanical mass when it reaches the desired vibration amplitude.

Role of electronic excited N2 in vibrational excitation of the N2 ground state at high latitudes

NASA Astrophysics Data System (ADS)

Campbell, L.; Cartwright, D. C.; Brunger, M. J.; Teubner, P. J. O.

2006-09-01

Vibrationally excited N2 is important in determining the ionospheric electron density and has also been proposed to play a role in the production of NO in disturbed atmospheres. We report here predictions of the absolute vibrational distributions in the ground electronic state of N2 produced by electron impact excitation, at noon and midnight under quiet geomagnetic conditions and disturbed conditions corresponding to the aurora IBCII+ and IBCIII+ at 60°N latitude and 0° longitude, at altitudes between 130 and 350 km. These predictions were obtained from a model which includes thermal excitation and direct electron impact excitation of the vibrational levels of the N2 ground state and its excited electronic states; radiative cascade from all excited electronic states to all vibrational levels of the ground electronic state; quenching by O, O2, and N2; molecular and ambipolar diffusion; and the dominant chemical reactions. Results from this study show that for both aurora and daytime electron environments: (1) cascade from the higher electronic states of N2 determines the population of the higher vibrational levels in the N2 ground state and (2) the effective ground state vibrational temperature for levels greater than 4 in N2 is predicted to be in the range 4000-13000 K for altitudes greater than 200 km. Correspondingly, the associated enhancement factor for the O+ reaction with vibrationally excited N2 to produce NO+ is predicted to increase with increasing altitude (up to a maximum at a height which increases with auroral strength) for both aurora and daytime environments and to increase with increasing auroral strength. The contribution of the cascade from the excited electronic states was evaluated and found to be relatively minor compared to the direct excitation process.

Dynamics Control Approaches to Improve Vibratory Environment of the Helicopter Aircrew

NASA Astrophysics Data System (ADS)

Wickramasinghe, Viresh Kanchana

Although helicopter has become a versatile mode of aerial transportation, high vibration levels leads to poor ride quality for its passengers and aircrew. Undesired vibration transmitted through the helicopter seats have been known to cause fatigue and discomfort to the aircrew in the short-term as well as neck strain and back pain injuries due to long-term exposure. This research study investigated the use of novel active as well as passive methodologies integrated in helicopter seats to mitigate the aircrew exposure to high vibration levels. Due to significantly less certification effort required to modify the helicopter seat structure, application of novel technologies to the seat is more practical compared to flight critical components such as the main rotor to reduce aircrew vibration. In particular, this research effort developed a novel adaptive seat mount approach based on active vibration control technology. This novel design that incorporated two stacked piezoelectric actuators as active struts increases the bending stiffness to avoid the low frequency resonance while generating forces to counteract higher harmonic vibration peaks. A real-time controller implemented using a feed-forward algorithm based on adaptive notches counteracted the forced vibration peaks while a robust feedback control algorithm suppressed the resonance modes. The effectiveness of the adaptive seat mount system was demonstrated through extensive closed-loop control tests on a full-scale helicopter seat using representative helicopter floor vibration profiles. Test results concluded that the proposed adaptive seat mount approach based on active control technology is a viable solution for the helicopter seat vibration control application. In addition, a unique flight test using a Bell-412 helicopter demonstrated that the aircrew is exposed to high levels of vibration during flight and that the whole body vibration spectrum varied substantially depending on operating conditions as well as the aircrew configurations. This investigation also demonstrated the suitability of integrating novel energy absorbing cushion materials to the seat as a low cost solution to improve aircrew vibration suppression. Therefore, it was recommended to pursue certification of novel seat cushion materials as a near-term solution to mitigate undesirable occupational health hazards in helicopter aircrew due to vibration exposure.

Vehicle for civil helicopter ride quality research

NASA Technical Reports Server (NTRS)

Snyder, W. J.; Schlegel, R. G.

1975-01-01

A research aircraft for investigating the factors involved in civil helicopter operations was developed for NASA Langley Research Center. The aircraft is a reconfigured 17000 kg (36000 lb) military transport helicopter. The basic aircraft was reconfigured with advanced acoustic treatment, air-conditioning, and a 16-seat airline cabin. During the spring of 1975, the aircraft was flight tested to measure interior environment characteristics - noise and vibration - and was flown on 60 subjective flight missions with over 600 different subjects. Data flights established noise levels somewhat higher than expected, with a pure tone at 1400 Hz and vertical vibration levels between 0.07g and 0.17g. The noise and vibration levels were documented during subjective flight evaluations as being the primary source of discomfort. The aircraft will be utilized to document in detail the impact of various noise and vibration levels on passenger comfort during typical short-haul missions.

Subharmonic resonances in high-order wave mixing in the quantized atomic motion in a one-dimensional optical lattice

NASA Astrophysics Data System (ADS)

Lopez, J. P.; de Almeida, A. J. F.; Tabosa, J. W. R.

2018-03-01

We report on the observation of subharmonic resonances in high-order wave mixing associated with the quantized vibrational levels of atoms trapped in a one-dimensional optical lattice created by two intense nearly counterpropagating coupling beams. These subharmonic resonances, occurring at ±1 /2 and ±1 /3 of the frequency separation between adjacent vibrational levels, are observed through phase-match angularly resolved six- and eight-wave mixing processes. We investigate how these resonances evolve with the intensity of the incident probe beam, which couples with one of the coupling beams to create anharmonic coherence gratings between adjacent vibrational levels. Our experimental results also show evidence of high-order processes associated with coherence involving nonadjacent vibrational levels. Moreover, we also demonstrate that these induced high-order coherences can be stored in the medium and the associated optical information retrieved after a controlled storage time.

Van der Waals potential and vibrational energy levels of the ground state radon dimer

NASA Astrophysics Data System (ADS)

Sheng, Xiaowei; Qian, Shifeng; Hu, Fengfei

2017-08-01

In the present paper, the ground state van der Waals potential of the Radon dimer is described by the Tang-Toennies potential model, which requires five essential parameters. Among them, the two dispersion coefficients C6 and C8 are estimated from the well determined dispersion coefficients C6 and C8 of Xe2. C10 is estimated by using the approximation equation that C6C10/C82 has an average value of 1.221 for all the rare gas dimers. With these estimated dispersion coefficients and the well determined well depth De and Re the Born-Mayer parameters A and b are derived. Then the vibrational energy levels of the ground state radon dimer are calculated. 40 vibrational energy levels are observed in the ground state of Rn2 dimer. The last vibrational energy level is bound by only 0.0012 cm-1.

Electromagnetically levitated vibration isolation system for the manufacturing process of silicon monocrystals

NASA Technical Reports Server (NTRS)

Kanemitsu, Yoichi; Watanabe, Katsuhide; Yano, Kenichi; Mizuno, Takayuki

1994-01-01

This paper introduces a study on an Electromagnetically Levitated Vibration Isolation System (ELVIS) for isolation control of large-scale vibration. This system features no mechanical contact between the isolation table and the installation floor, using a total of four electromagnetic actuators which generate magnetic levitation force in the vertical and horizontal directions. The configuration of the magnet for the vertical direction is designed to prevent any generation of restoring vibratory force in the horizontal direction. The isolation system is set so that vibration control effects due to small earthquakes can be regulated to below 5(gal) versus horizontal vibration levels of the installation floor of up t 25(gal), and those in the horizontal relative displacement of up to 30 (mm) between the floor and levitated isolation table. In particular, studies on the relative displacement between the installation floor and the levitated isolation table have been made for vibration control in the horizontal direction. In case of small-scale earthquakes (Taft wave scaled: max. 25 gal), the present system has been confirmed to achieve a vibration isolation to a level below 5 gal. The vibration transmission ratio of below 1/10 has been achieved versus continuous micro-vibration (approx. one gal) in the horizontal direction on the installation floor.

Assessment of whole-body vibration exposures and influencing factors for quarry haul truck drivers and loader operators

PubMed Central

Mayton, Alan G.; Jobes, Christopher C.; Gallagher, Sean

2015-01-01

To further assess vibration exposure on haul trucks (HTs) and front-end wheel loaders (FELs), follow-up investigations were conducted at two US crushed stone operations. The purpose was to: 1) evaluate factors such as load/no-load conditions, speed, load capacity, vehicle age, and seat transmissibility relative to vibration exposure; 2) compare exposure levels with existing ISO/ANSI and EUGPG guidelines. Increasing HT speed increased recorded vibration at the chassis and seat as expected. Neither vehicle load nor vehicle speed increased transmissibility. Increasing HT size and age did show transmissibility decreasing. HT dominant-axis wRMS levels (most often the y-axis, lateral or side-to-side direction) were predominantly within the health guidance caution zone (HGCZ). However, several instances showed vibration dose value (VDV) above the exposure limit value (ELV) for the ISO/ANSI guidelines. VDV levels (all dominant x-axis or fore-aft) were within and above the HGCZ for the EUGPG and above the HGCZ for ISO/ANSI guidelines. PMID:26361493

Ring Laser Gyro Resonator Design

DTIC Science & Technology

1994-06-20

vibration environment could cause errors in measured RLG rotation rates due to vibration (tilt) of the resonator mirrors . Vibration-induced mirror tilt...the RLG resonator design theoretically and calculated pertinent parameters such as the beam diameter at the aperture, cavity mirror alignment...sensitivities, and power loss due to aperture occlusion. The mirror vibration levels required to significantly affect the laser power were then calculated for

Active vibration control of structures undergoing bending vibrations

NASA Technical Reports Server (NTRS)

Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor)

1995-01-01

An active vibration control subassembly for a structure (such as a jet engine duct or a washing machine panel) undergoing bending vibrations caused by a source (such as the clothes agitator of the washing machine) independent of the subassembly. A piezoceramic actuator plate is vibratable by an applied electric AC signal. The plate is connected to the structure such that vibrations in the plate induced by the AC signal cause canceling bending vibrations in the structure and such that the plate is compressively pre-stressed along the structure when the structure is free of any bending vibrations. The compressive prestressing increases the amplitude of the canceling bending vibrations before the critical tensile stress level of the plate is reached. Preferably, a positive electric DC bias is also applied to the plate in its poling direction.

Vibration in car repair work.

PubMed

Hansson, J E; Eklund, L; Kihlberg, S; Ostergren, C E

1987-03-01

The main objective of the study was to find efficient hand tools which caused only minor vibration loading. Vibration measurements were carried out under standardised working conditions. The time during which car body repairers in seven companies were exposed to vibration was determined. Chisel hammers, impact wrenches, sanders and saws were the types of tools which generated the highest vibration accelerations. The average daily exposure at the different garages ranged from 22 to 70 min. The risk of vibration injury is currently rated as high. The difference between the highest and lowest levels of vibration was considerable in most tool categories. Therefore the choice of tool has a major impact on the magnitude of vibration exposure. The importance of choosing the right tools and working methods is discussed and a counselling service on vibration is proposed.

Ares I-X Launch Abort System, Crew Module, and Upper Stage Simulator Vibroacoustic Flight Data Evaluation, Comparison to Predictions, and Recommendations for Adjustments to Prediction Methodology and Assumptions

NASA Technical Reports Server (NTRS)

Smith, Andrew; Harrison, Phil

2010-01-01

The National Aeronautics and Space Administration (NASA) Constellation Program (CxP) has identified a series of tests to provide insight into the design and development of the Crew Launch Vehicle (CLV) and Crew Exploration Vehicle (CEV). Ares I-X was selected as the first suborbital development flight test to help meet CxP objectives. The Ares I-X flight test vehicle (FTV) is an early operational model of CLV, with specific emphasis on CLV and ground operation characteristics necessary to meet Ares I-X flight test objectives. The in-flight part of the test includes a trajectory to simulate maximum dynamic pressure during flight and perform a stage separation of the Upper Stage Simulator (USS) from the First Stage (FS). The in-flight test also includes recovery of the FS. The random vibration response from the ARES 1-X flight will be reconstructed for a few specific locations that were instrumented with accelerometers. This recorded data will be helpful in validating and refining vibration prediction tools and methodology. Measured vibroacoustic environments associated with lift off and ascent phases of the Ares I-X mission will be compared with pre-flight vibration predictions. The measured flight data was given as time histories which will be converted into power spectral density plots for comparison with the maximum predicted environments. The maximum predicted environments are documented in the Vibroacoustics and Shock Environment Data Book, AI1-SYS-ACOv4.10 Vibration predictions made using statistical energy analysis (SEA) VAOne computer program will also be incorporated in the comparisons. Ascent and lift off measured acoustics will also be compared to predictions to assess whether any discrepancies between the predicted vibration levels and measured vibration levels are attributable to inaccurate acoustic predictions. These comparisons will also be helpful in assessing whether adjustments to prediction methodologies are needed to improve agreement between the predicted and measured flight data. Future assessment will incorporate hybrid methods in VAOne analysis (i.e., boundary element methods, BEM and finite element methods, FEM). These hybrid methods will enable the ability to import NASTRAN models providing much more detailed modeling of the underlying beams and support structure of the ARES 1-X test vehicle. Measured acoustic data will be incorporated into these analyses to improve correlation for additional post flight analysis.

Interior noise and vibration measurements on operational military helicopters and comparisons with various ride quality criteria

NASA Technical Reports Server (NTRS)

Clevenson, S. A.; Leatherwood, J. D.; Hollenbaugh, D. D.

1983-01-01

The results of physical measurements of the interior noise and vibration obtained within eight operational military helicopters are presented. The data were extensively analyzed and are presented in the following forms: noise and vibration spectra, overall root-mean-square acceleration levels in three linear axes, peak accelerations at dominant blade passage frequencies, acceleration exceedance data, and overall and ""A'' weighted sound pressure levels. Peak acceleration levels were compared to the ISO 1-hr reduced comfort and fatigue decreased proficiency boundaries and the NASA discomfort criteria. The ""A'' weighted noise levels were compared to the NASA annoyance criteria, and the overall noise spectra were compared to MIL-STD-1294 (""Acoustical Noise Limits in Helicopters''). Specific vibration components at blade passage frequencies for several aircraft exceeded both the ISO reduced comfort boundary and the NASA passenger discomfort criteria. The ""A'' weighted noise levels, corrected for SPH-4 helmet attenuation characteristics, exceeded the NASA annoyance threshold for several aircraft.

An SVM-Based Classifier for Estimating the State of Various Rotating Components in Agro-Industrial Machinery with a Vibration Signal Acquired from a Single Point on the Machine Chassis

PubMed Central

Ruiz-Gonzalez, Ruben; Gomez-Gil, Jaime; Gomez-Gil, Francisco Javier; Martínez-Martínez, Víctor

2014-01-01

The goal of this article is to assess the feasibility of estimating the state of various rotating components in agro-industrial machinery by employing just one vibration signal acquired from a single point on the machine chassis. To do so, a Support Vector Machine (SVM)-based system is employed. Experimental tests evaluated this system by acquiring vibration data from a single point of an agricultural harvester, while varying several of its working conditions. The whole process included two major steps. Initially, the vibration data were preprocessed through twelve feature extraction algorithms, after which the Exhaustive Search method selected the most suitable features. Secondly, the SVM-based system accuracy was evaluated by using Leave-One-Out cross-validation, with the selected features as the input data. The results of this study provide evidence that (i) accurate estimation of the status of various rotating components in agro-industrial machinery is possible by processing the vibration signal acquired from a single point on the machine structure; (ii) the vibration signal can be acquired with a uniaxial accelerometer, the orientation of which does not significantly affect the classification accuracy; and, (iii) when using an SVM classifier, an 85% mean cross-validation accuracy can be reached, which only requires a maximum of seven features as its input, and no significant improvements are noted between the use of either nonlinear or linear kernels. PMID:25372618

An SVM-based classifier for estimating the state of various rotating components in agro-industrial machinery with a vibration signal acquired from a single point on the machine chassis.

PubMed

Ruiz-Gonzalez, Ruben; Gomez-Gil, Jaime; Gomez-Gil, Francisco Javier; Martínez-Martínez, Víctor

2014-11-03

The goal of this article is to assess the feasibility of estimating the state of various rotating components in agro-industrial machinery by employing just one vibration signal acquired from a single point on the machine chassis. To do so, a Support Vector Machine (SVM)-based system is employed. Experimental tests evaluated this system by acquiring vibration data from a single point of an agricultural harvester, while varying several of its working conditions. The whole process included two major steps. Initially, the vibration data were preprocessed through twelve feature extraction algorithms, after which the Exhaustive Search method selected the most suitable features. Secondly, the SVM-based system accuracy was evaluated by using Leave-One-Out cross-validation, with the selected features as the input data. The results of this study provide evidence that (i) accurate estimation of the status of various rotating components in agro-industrial machinery is possible by processing the vibration signal acquired from a single point on the machine structure; (ii) the vibration signal can be acquired with a uniaxial accelerometer, the orientation of which does not significantly affect the classification accuracy; and, (iii) when using an SVM classifier, an 85% mean cross-validation accuracy can be reached, which only requires a maximum of seven features as its input, and no significant improvements are noted between the use of either nonlinear or linear kernels.

Forced Vibrations of a Cantilever Beam

ERIC Educational Resources Information Center

Repetto, C. E.; Roatta, A.; Welti, R. J.

2012-01-01

The theoretical and experimental solutions for vibrations of a vertical-oriented, prismatic, thin cantilever beam are studied. The beam orientation is "downwards", i.e. the clamped end is above the free end, and it is subjected to a transverse movement at a selected frequency. Both the behaviour of the device driver and the beam's weak-damping…

Theoretical studies of solar-pumped lasers

NASA Technical Reports Server (NTRS)

Harries, W. L.

1983-01-01

Metallic vapor lasers of Na2 and Li2 are examined as solar energy converters. The absorbed photons cause transitions to vibrational-rotational levels in an upper electronic state. With broad band absorption the resultant levels can have quantum numbers considerably higher than the upper lasing level. The excited molecule then relaxes to the upper lasing level which is one of the lower vibrational levels in the upper electronic state. The relaxation occurs from collisions, provided the molecule is not quenched into the ground level electronic state. Lasing occurs with a transition to a vibrational level in the lower electronic state. Rough estimates of solar power efficiencies are 1 percent for Na2 and probably a similar figure for Li2. The nondissociative lasers from a family distinct from materials which dissociate to yield an excited atom.

Vibration-rotation-tunneling dynamics in small water clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pugliano, Nick

The goal of this work is to characterize the intermolecular vibrations of small water clusters. Using tunable far infrared laser absorption spectroscopy, large amplitude vibration-rotation-tunneling (VRT) dynamics in vibrationally excited states of the water dimer and the water trimer are investigated. This study begins with the measurement of 12 VRT subbands, consisting of approximately 230 transitions, which are assigned to an 82.6 cm -1 intermolecular vibration of the water dimer-d 4. Each of the VRT subbands originate from K a''=0 and terminate in either K a'=0 or 1. These data provide a complete characterization of the tunneling dynamics in themore » vibrationally excited state as well as definitive symmetry labels for all VRT energy levels. Furthermore, an accurate value for the A' rotational constant is found to agree well with its corresponding ground state value. All other excited state rotational constants are fitted, and discussed in terms of the corresponding ground state constants. In this vibration, the quantum tunneling motions are determined to exhibit large dependencies with both the K a' quantum number and the vibrational coordinate, as is evidenced by the measured tunneling splittings. The generalized internal-axis-method treatment which has been developed to model the tunneling dynamics, is considered for the qualitative description of each tunneling pathway, however, the variation of tunneling splittings with vibrational excitation indicate that the high barrier approximation does not appear to be applicable for this vibrational coordinate. The data are consistent with a motion possessing a' symmetry, and the vibration is assigned as the v 12 acceptor bending coordinate. This assignment is in agreement with the vibrational symmetry, the resultsof high level ab initio calculations, and preliminary data assigned to the analogous vibration in the D 2O-DOH isotopomer.« less

Stereo-selective partitioning of translation-to-internal energy conversion in gas ensembles

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCaffery, Anthony J., E-mail: A.J.McCaffery@sussex.ac.uk

2014-11-07

A recent computational study of translation-to-internal energy transfer to H{sub 2} (v = 0,j = 0), hereinafter denoted H{sub 2} (0;0), in a bath of H atoms [A. J. McCaffery and R. J. Marsh, J. Chem. Phys. 139, 234310 (2013)] revealed an unexpected energy partitioning in which the H{sub 2} vibrational temperature greatly exceeds that of rotation. This occurs despite rotation and vibration distributions being close to Boltzmann from early in ensemble evolution. In this work, the study is extended to include H{sub 2} (0;0), O{sub 2} (0;0), and HF (0;0) in a wide range of atomic bath gases comprisingmore » some 22 ensembles in all. Translation-to-internal energy conversion in the systems studied was found to be relatively inefficient, falling approximately with (√μ′){sup −1} as bath gas mass increases, where μ′ is the reduced mass of the diatomic–bath gas pair. In all 22 systems studied, T{sub v} exceeds T{sub r} – by a factor > 4 for some pairs. Analysis of the constraints that influence (0;0) → (1;j) excitation for each diatomic–atom pair in momentum–angular momentum space demonstrates that a vibrational preference results from energy constraints that limit permitted collision trajectories to those of low effective impact parameter, i.e., to those that are axial or near axial on impact with the Newton surface. This implies that a steric constraint is an inherent feature of vibration-rotation excitation and arises because momentum and energy barriers must be overcome before rotational states may be populated in the higher vibrational level.« less

Influence of long-wavelength track irregularities on the motion of a high-speed train

NASA Astrophysics Data System (ADS)

Hung, C. F.; Hsu, W. L.

2018-01-01

Vertical track irregularities over viaducts in high-speed rail systems could be possibly caused by concrete creep if pre-stressed concrete bridges are used. For bridge spans that are almost uniformly distributed, track irregularity exhibits a near-regular wave profile that excites car bodies as a high-speed train moves over the bridge system. A long-wavelength irregularity induces low-frequency excitation that may be close to the natural frequencies of the train suspension system, thereby causing significant vibration of the car body. This paper investigates the relationship between the levels of car vibration, bridge vibration, track irregularity, and the train speed. First, this study investigates the vibration levels of a high-speed train and bridge system using 3D finite-element (FE) transient dynamic analysis, before and after adjustment of vertical track irregularities by means of installing shimming plates under rail pads. The analysis models are validated by in situ measurements and on-board measurement. Parametric studies of car body vibration and bridge vibration under three different levels of track irregularity at five train speeds and over two bridge span lengths are conducted using the FE model. Finally, a discontinuous shimming pattern is proposed to avoid vehicle suspension resonance.

Vibration Training Triggers Brown Adipocyte Relative Protein Expression in Rat White Adipose Tissue

PubMed Central

Sun, Chao; Zeng, Ruixia; Cao, Ge; Song, Zhibang; Zhang, Yibo; Liu, Chang

2015-01-01

Recently, vibration training is considered as a novel strategy of weight loss; however, its mechanisms are still unclear. In this study, normal or high-fat diet-induced rats were trained by whole body vibration for 8 weeks. We observed that the body weight and fat metabolism index, blood glucose, triglyceride, cholesterol, and free fatty acid in obesity rats decreased significantly compared with nonvibration group (n = 6). Although intrascapular BAT weight did not change significantly, vibration enhanced ATP reduction and increased protein level of the key molecule of brown adipose tissue (BAT), PGC-1α, and UCP1 in BAT. Interestingly, the adipocytes in retroperitoneal white adipose tissue (WAT) became smaller due to vibration exercise and had higher protein level of the key molecule of brown adipose tissue (BAT), PGC-1α, and UCP1 and inflammatory relative proteins, IL-6 and TNFα. Simultaneously, ATP content and PPARγ protein level in WAT became less in rats compared with nonvibration group. The results indicated that vibration training changed lipid metabolism in rats and promoted brown fat-like change in white adipose tissues through triggering BAT associated gene expression, inflammatory reflect, and reducing energy reserve. PMID:26125027

Gearbox Tooth Cut Fault Diagnostics Using Acoustic Emission and Vibration Sensors — A Comparative Study

PubMed Central

Qu, Yongzhi; He, David; Yoon, Jae; Van Hecke, Brandon; Bechhoefer, Eric; Zhu, Junda

2014-01-01

In recent years, acoustic emission (AE) sensors and AE-based techniques have been developed and tested for gearbox fault diagnosis. In general, AE-based techniques require much higher sampling rates than vibration analysis-based techniques for gearbox fault diagnosis. Therefore, it is questionable whether an AE-based technique would give a better or at least the same performance as the vibration analysis-based techniques using the same sampling rate. To answer the question, this paper presents a comparative study for gearbox tooth damage level diagnostics using AE and vibration measurements, the first known attempt to compare the gearbox fault diagnostic performance of AE- and vibration analysis-based approaches using the same sampling rate. Partial tooth cut faults are seeded in a gearbox test rig and experimentally tested in a laboratory. Results have shown that the AE-based approach has the potential to differentiate gear tooth damage levels in comparison with the vibration-based approach. While vibration signals are easily affected by mechanical resonance, the AE signals show more stable performance. PMID:24424467

Zn-metalloprotease sequences in extremophiles

NASA Astrophysics Data System (ADS)

Holden, T.; Dehipawala, S.; Golebiewska, U.; Cheung, E.; Tremberger, G., Jr.; Williams, E.; Schneider, P.; Gadura, N.; Lieberman, D.; Cheung, T.

2010-09-01

The Zn-metalloprotease family contains conserved amino acid structures such that the nucleotide fluctuation at the DNA level would exhibit correlated randomness as described by fractal dimension. A nucleotide sequence fractal dimension can be calculated from a numerical series consisting of the atomic numbers of each nucleotide. The structure's vibration modes can also be studied using a Gaussian Network Model. The vibration measure and fractal dimension values form a two-dimensional plot with a standard vector metric that can be used for comparison of structures. The preference for amino acid usage in extremophiles may suppress nucleotide fluctuations that could be analyzed in terms of fractal dimension and Shannon entropy. A protein level cold adaptation study of the thermolysin Zn-metalloprotease family using molecular dynamics simulation was reported recently and our results show that the associated nucleotide fluctuation suppression is consistent with a regression pattern generated from the sequences's fractal dimension and entropy values (R-square { 0.98, N =5). It was observed that cold adaptation selected for high entropy and low fractal dimension values. Extension to the Archaemetzincin M54 family in extremophiles reveals a similar regression pattern (R-square = 0.98, N = 6). It was observed that the metalloprotease sequences of extremely halophilic organisms possess high fractal dimension and low entropy values as compared with non-halophiles. The zinc atom is usually bonded to the histidine residue, which shows limited levels of vibration in the Gaussian Network Model. The variability of the fractal dimension and entropy for a given protein structure suggests that extremophiles would have evolved after mesophiles, consistent with the bias usage of non-prebiotic amino acids by extremophiles. It may be argued that extremophiles have the capacity to offer extinction protection during drastic changes in astrobiological environments.

Correlation of finite-element structural dynamic analysis with measured free vibration characteristics for a full-scale helicopter fuselage

NASA Technical Reports Server (NTRS)

Kenigsberg, I. J.; Dean, M. W.; Malatino, R.

1974-01-01

The correlation achieved with each program provides the material for a discussion of modeling techniques developed for general application to finite-element dynamic analyses of helicopter airframes. Included are the selection of static and dynamic degrees of freedom, cockpit structural modeling, and the extent of flexible-frame modeling in the transmission support region and in the vicinity of large cut-outs. The sensitivity of predicted results to these modeling assumptions are discussed. Both the Sikorsky Finite-Element Airframe Vibration analysis Program (FRAN/Vibration Analysis) and the NASA Structural Analysis Program (NASTRAN) have been correlated with data taken in full-scale vibration tests of a modified CH-53A helicopter.

The qualitative assessment of pneumatic actuators operation in terms of vibration criteria

NASA Astrophysics Data System (ADS)

Hetmanczyk, M. P.; Michalski, P.

2015-11-01

The work quality of pneumatic actuators can be assessed in terms of multiple criteria. In the case of complex systems with pneumatic actuators retained at end positions (with occurrence of piston impact in cylinder covers) the vibration criteria constitute the most reliable indicators. The paper presents an impact assessment on the operating condition of the rodless pneumatic cylinder regarding to selected vibrational symptoms. On the basis of performed analysis the authors had shown meaningful premises allowing an evaluation of the performance and tuning of end position damping piston movement with usage the most common diagnostic tools (portable vibration analyzers). The presented method is useful in tuning of parameters in industrial conditions.

Quantifying the Performances of DFT for Predicting Vibrationally Resolved Optical Spectra: Asymmetric Fluoroborate Dyes as Working Examples.

PubMed

Bednarska, Joanna; Zaleśny, Robert; Bartkowiak, Wojciech; Ośmiałowski, Borys; Medved', Miroslav; Jacquemin, Denis

2017-09-12

This article aims at a quantitative assessment of the performances of a panel of exchange-correlation functionals, including semilocal (BLYP and PBE), global hybrids (B3LYP, PBE0, M06, BHandHLYP, M06-2X, and M06-HF), and range-separated hybrids (CAM-B3LYP, LC-ωPBE, LC-BLYP, ωB97X, and ωB97X-D), in predicting the vibrationally resolved absorption spectra of BF 2 -carrying compounds. To this end, for 19 difluoroborates as examples, we use, as a metric, the vibrational reorganization energy (λ vib ) that can be determined based on the computationally efficient linear coupling model (a.k.a. vertical gradient method). The reference values of λ vib were determined by employing the CC2 method combined with the cc-pVTZ basis set for a representative subset of molecules. To validate the performances of CC2, comparisons with experimental data have been carried out as well. This study shows that the vibrational reorganization energy, involving Huang-Rhys factors and normal-mode frequencies, can indeed be used to quantify the reliability of functionals in the calculations of the vibrational fine structure of absorption bands, i.e., an accurate prediction of the vibrational reorganization energy leads to absorption band shapes better fitting the selected reference. The CAM-B3LYP, M06-2X, ωB97X-D, ωB97X, and BHandHLYP functionals all deliver vibrational reorganization energies with absolute relative errors smaller than 20% compared to CC2, whereas 10% accuracy can be achieved with the first three functionals. Indeed, the set of examined exchange-correlation functionals can be divided into three groups: (i) BLYP, B3LYP, PBE, PBE0, and M06 yield inaccurate band shapes (λ vib,TDDFT < λ vib,CC2 ), (ii) BHandHLYP, CAM-B3LYP, M06-2X, ωB97X, and ωB97X-D provide accurate band shapes (λ vib,TDDFT ≈ λ vib,CC2 ), and (iii) LC-ωPBE, LC-BLYP, and M06-HF deliver rather poor band topologies (λ vib,TDDFT > λ vib,CC2 ). This study also demonstrates that λ vib can be reliably estimated using the CC2 model and the relatively small cc-pVDZ basis set. Therefore, the linear coupling model combined with the CC2/cc-pVDZ level of theory can be used as a very efficient approach to determine λ vib values that can be used to select the most adequate functional for more accurate vibronic calculations, e.g., including more refined models and environmental effects.

Low vibration laboratory with a single-stage vibration isolation for microscopy applications.

PubMed

Voigtländer, Bert; Coenen, Peter; Cherepanov, Vasily; Borgens, Peter; Duden, Thomas; Tautz, F Stefan

2017-02-01

The construction and the vibrational performance of a low vibration laboratory for microscopy applications comprising a 100 ton floating foundation supported by passive pneumatic isolators (air springs), which rest themselves on a 200 ton solid base plate, are discussed. The optimization of the air spring system leads to a vibration level on the floating floor below that induced by an acceleration of 10 ng for most frequencies. Additional acoustic and electromagnetic isolation is accomplished by a room-in-room concept.

Vibration and recoil control of pneumatic hammers. [by air flow pressure regulation

NASA Technical Reports Server (NTRS)

Constantinescu, I. N.; Darabont, A. V.

1974-01-01

Vibration sources are described for pneumatic hammers used in the mining industry (pick hammers), in boiler shops (riveting hammers), etc., bringing to light the fact that the principal vibration source is the variation in air pressure inside the cylinder. The present state of the art of vibration control of pneumatic hammers as it is practiced abroad, and the solutions adopted for this purpose, are discussed. A new type of pneumatic hammer with a low noise and vibration level is presented.

Anharmonic force field and vibrational dynamics of CH2F2 up to 5000 cm(-1) studied by Fourier transform infrared spectroscopy and state-of-the-art ab initio calculations.

PubMed

Tasinato, Nicola; Regini, Giorgia; Stoppa, Paolo; Pietropolli Charmet, Andrea; Gambi, Alberto

2012-06-07

Difluoromethane (CH(2)F(2), HFC-32) is a molecule used in refrigerant mixtures as a replacement of the more environmentally hazardous, ozone depleting, chlorofluorocarbons. On the other hand, presenting strong vibration-rotation bands in the 9 μm atmospheric window, it is a greenhouse gas which contributes to global warming. In the present work, the vibrational and ro-vibrational properties of CH(2)F(2), providing basic data for its atmospheric modeling, are studied in detail by coupling medium resolution Fourier transform infrared spectroscopy to high-level electronic structure ab initio calculations. Experimentally a full quantum assignment and accurate integrated absorption cross sections are obtained up to 5000 cm(-1). Ab initio calculations are carried out by using CCSD(T) theory and large basis sets of either the correlation consistent or atomic natural orbital hierarchies. By using vibrational perturbation theory to second order a complete set of vibrational and ro-vibrational parameters is derived from the ab initio quartic anharmonic force fields, which well compares with the spectroscopic constants retrieved experimentally. An excellent agreement between theory and experiment is achieved for vibrational energy levels and integrated absorption cross sections: transition frequencies up to four quanta of vibrational excitation are reproduced with a root mean square deviation (RMSD) of 7 cm(-1) while intensities are predicted within few km mol(-1) from the experiment. Basis set performances and core correlation effects are discussed throughout the paper. Particular attention is focused in the understanding of the anharmonic couplings which rule the vibrational dynamics of the |ν(1)>, |2ν(8)>, |2ν(2)> three levels interacting system. The reliability of the potential energy and dipole moment surfaces in reproducing the vibrational eigenvalues and intensities as well as in modeling the vibrational and ro-vibrational mixings over the whole 400-5000 cm(-1) region is also demonstrated by spectacular spectral simulations carried out by using the ro-vibrational Hamiltonian constants, and the relevant coupling terms, obtained from the perturbation treatment of the ab initio anharmonic force field. The present results suggest CH(2)F(2) as a prototype molecule to test ab initio calculations and theoretical models.

Anharmonic force field and vibrational dynamics of CH2F2 up to 5000 cm-1 studied by Fourier transform infrared spectroscopy and state-of-the-art ab initio calculations

NASA Astrophysics Data System (ADS)

Tasinato, Nicola; Regini, Giorgia; Stoppa, Paolo; Charmet, Andrea Pietropolli; Gambi, Alberto

2012-06-01

Difluoromethane (CH2F2, HFC-32) is a molecule used in refrigerant mixtures as a replacement of the more environmentally hazardous, ozone depleting, chlorofluorocarbons. On the other hand, presenting strong vibration-rotation bands in the 9 μm atmospheric window, it is a greenhouse gas which contributes to global warming. In the present work, the vibrational and ro-vibrational properties of CH2F2, providing basic data for its atmospheric modeling, are studied in detail by coupling medium resolution Fourier transform infrared spectroscopy to high-level electronic structure ab initio calculations. Experimentally a full quantum assignment and accurate integrated absorption cross sections are obtained up to 5000 cm-1. Ab initio calculations are carried out by using CCSD(T) theory and large basis sets of either the correlation consistent or atomic natural orbital hierarchies. By using vibrational perturbation theory to second order a complete set of vibrational and ro-vibrational parameters is derived from the ab initio quartic anharmonic force fields, which well compares with the spectroscopic constants retrieved experimentally. An excellent agreement between theory and experiment is achieved for vibrational energy levels and integrated absorption cross sections: transition frequencies up to four quanta of vibrational excitation are reproduced with a root mean square deviation (RMSD) of 7 cm-1 while intensities are predicted within few km mol-1 from the experiment. Basis set performances and core correlation effects are discussed throughout the paper. Particular attention is focused in the understanding of the anharmonic couplings which rule the vibrational dynamics of the |ν1⟩, |2ν8⟩, |2ν2⟩ three levels interacting system. The reliability of the potential energy and dipole moment surfaces in reproducing the vibrational eigenvalues and intensities as well as in modeling the vibrational and ro-vibrational mixings over the whole 400-5000 cm-1 region is also demonstrated by spectacular spectral simulations carried out by using the ro-vibrational Hamiltonian constants, and the relevant coupling terms, obtained from the perturbation treatment of the ab initio anharmonic force field. The present results suggest CH2F2 as a prototype molecule to test ab initio calculations and theoretical models.

Vibrational quasi-degenerate perturbation theory with optimized coordinates: Applications to ethylene and trans-1,3-butadiene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yagi, Kiyoshi, E-mail: kiyoshi.yagi@riken.jp; Otaki, Hiroki

A perturbative extension to optimized coordinate vibrational self-consistent field (oc-VSCF) is proposed based on the quasi-degenerate perturbation theory (QDPT). A scheme to construct the degenerate space (P space) is developed, which incorporates degenerate configurations and alleviates the divergence of perturbative expansion due to localized coordinates in oc-VSCF (e.g., local O–H stretching modes of water). An efficient configuration selection scheme is also implemented, which screens out the Hamiltonian matrix element between the P space configuration (p) and the complementary Q space configuration (q) based on a difference in their quantum numbers (λ{sub pq} = ∑{sub s}|p{sub s} − q{sub s}|). Itmore » is demonstrated that the second-order vibrational QDPT based on optimized coordinates (oc-VQDPT2) smoothly converges with respect to the order of the mode coupling, and outperforms the conventional one based on normal coordinates. Furthermore, an improved, fast algorithm is developed for optimizing the coordinates. First, the minimization of the VSCF energy is conducted in a restricted parameter space, in which only a portion of pairs of coordinates is selectively transformed. A rational index is devised for this purpose, which identifies the important coordinate pairs to mix from others that may remain unchanged based on the magnitude of harmonic coupling induced by the transformation. Second, a cubic force field (CFF) is employed in place of a quartic force field, which bypasses intensive procedures that arise due to the presence of the fourth-order force constants. It is found that oc-VSCF based on CFF together with the pair selection scheme yields the coordinates similar in character to the conventional ones such that the final vibrational energy is affected very little while gaining an order of magnitude acceleration. The proposed method is applied to ethylene and trans-1,3-butadiene. An accurate, multi-resolution potential, which combines the MP2 and coupled-cluster with singles, doubles, and perturbative triples level of electronic structure theory, is generated and employed in the oc-VQDPT2 calculation to obtain the fundamental tones as well as selected overtones/combination tones coupled to the fundamentals through the Fermi resonance. The calculated frequencies of ethylene and trans-1,3-butadiene are found to be in excellent agreement with the experimental values with a mean absolute error of 8 and 9 cm{sup −1}, respectively.« less

Health risks of vibration exposure to wheelchair users in the community

PubMed Central

Garcia-Mendez, Yasmin; Pearlman, Jonathan L.; Boninger, Michael L.; Cooper, Rory A.

2013-01-01

Objective The purpose of this study was to evaluate whole-body vibration (WBV) exposure to wheelchair (WC) users in their communities and to determine the effect of WC frame type (folding, rigid, and suspension) in reducing WBV transmitted to the person. Design An observational case-control study of the WBV exposure levels among WC users. Participants Thirty-seven WC users, with no pressure sores, 18 years old or older and able to perform independent transfers. Main outcome measures WC users were monitored for 2 weeks to collect WBV exposure, as well as activity levels, by using custom vibration and activity data-loggers. Vibration levels were evaluated using ISO 2631-1 methods. Results All WC users who participated in this study were continuously exposed to WBV levels at the seat that were within and above the health caution zone specified by ISO 2631-1 during their day-to-day activities (0.83 ± 0.17 m/second2, weighted root-mean-squared acceleration, for 13.07 ± 3.85 hours duration of exposure). WCs with suspension did not attenuate vibration transmitted to WC users (V = 0.180, F(8, 56) = 0.692, P = 0.697). Conclusions WBV exposure to WC users exceeds international standards. Suspension systems need to be improved to reduce vibrations transmitted to the users. PMID:23820152

Influence of different intensities of vibration on proliferation and differentiation of human periodontal ligament stem cells.

PubMed

Zhang, Chunxiang; Lu, Yanqin; Zhang, Linkun; Liu, Yang; Zhou, Yi; Chen, Yangxi; Yu, Haiyang

2015-06-19

To understand the effects of low-magnitude, high-frequency (LMHF) mechanical vibration at different intensities on human periodontal ligament stem cell (hPDLSC) proliferation and osteogenic differentiation. The effect of vibration on hPDLSC proliferation, osteogenic differentiation, tenogenic differentiation and cytoskeleton was assessed at the cellular, genetic and protein level. The PDLSC proliferation was decreased after different magnitudes of mechanical vibration; however, there were no obvious senescent cells in the experimental and the static control group. Expression of osteogenesis markers was increased. The expression of alkaline phosphatase (ALP) and osteocalcin (OCN) mRNA was up-regulated at 0.1 g, 0.3 g, 0.6 g and 0.9 g magnitude, with the peak at 0.3 g. The type I collagen (Col-I) level was increased after vibration exposure at 0.1 g, 0.3 g, and 0.6 g, peaking at 0.3 g. The expression levels of both mRNA and protein of Runx2 and osterix (OSX) significantly increased at a magnitude of 0.1 g to 0.9 g, reached a peak at 0.3 g and then decreased slowly. The scleraxis, tenogenic markers, and mRNA expression decreased at 0.05 g, 0.1 g, and 0.3 g, and significantly increased at 0.6 g and 0.9 g. Compared with the static group, the F-actin stress fibers of hPDLSCs became thicker and clearer following vibration. The LMHF mechanical vibration promotes PDLSC osteogenic differentiation and implies the existence of a magnitude-dependent effect of vibration on determining PDLSC commitment to the osteoblast lineage. Changes in the cytoskeleton of hPDLSCs after vibration may be one of the mechanisms of the biological effects.

Finite frequency current noise in the Holstein model

NASA Astrophysics Data System (ADS)

Stadler, P.; Rastelli, G.; Belzig, W.

2018-05-01

We investigate the effects of local vibrational excitations in the nonsymmetrized current noise S (ω ) of a nanojunction. For this purpose, we analyze a simple model—the Holstein model—in which the junction is described by a single electronic level that is coupled to two metallic leads and to a single vibrational mode. Using the Keldysh Green's function technique, we calculate the nonsymmetrized current noise to the leading order in the charge-vibration interaction. For the noise associated to the latter, we identify distinct terms corresponding to the mean-field noise and the vertex correction. The mean-field result can be further divided into an elastic correction to the noise and in an inelastic correction, the second one being related to energy exchange with the vibration. To illustrate the general behavior of the noise induced by the charge-vibration interaction, we consider two limit cases. In the first case, we assume a strong coupling of the dot to the leads with an energy-independent transmission, whereas in the second case we assume a weak tunneling coupling between the dot and the leads such that the transport occurs through a sharp resonant level. We find that the noise associated to the vibration-charge interaction shows a complex pattern as a function of the frequency ω and of the transmission function or of the dot's energy level. Several transitions from enhancement to suppression of the noise occurs in different regions, which are determined, in particular, by the vibrational frequency. Remarkably, in the regime of an energy-independent transmission, the zero-order elastic noise vanishes at perfect transmission and at positive frequency, whereas the noise related to the charge-vibration interaction remains finite, enabling the analysis of the pure vibrational-induced current noise.

Influence of different intensities of vibration on proliferation and differentiation of human periodontal ligament stem cells

PubMed Central

Zhang, Chunxiang; Lu, Yanqin; Zhang, Linkun; Liu, Yang; Zhou, Yi; Chen, Yangxi

2015-01-01

Introduction To understand the effects of low-magnitude, high-frequency (LMHF) mechanical vibration at different intensities on human periodontal ligament stem cell (hPDLSC) proliferation and osteogenic differentiation. Material and methods The effect of vibration on hPDLSC proliferation, osteogenic differentiation, tenogenic differentiation and cytoskeleton was assessed at the cellular, genetic and protein level. Results The PDLSC proliferation was decreased after different magnitudes of mechanical vibration; however, there were no obvious senescent cells in the experimental and the static control group. Expression of osteogenesis markers was increased. The expression of alkaline phosphatase (ALP) and osteocalcin (OCN) mRNA was up-regulated at 0.1 g, 0.3 g, 0.6 g and 0.9 g magnitude, with the peak at 0.3 g. The type I collagen (Col-I) level was increased after vibration exposure at 0.1 g, 0.3 g, and 0.6 g, peaking at 0.3 g. The expression levels of both mRNA and protein of Runx2 and osterix (OSX) significantly increased at a magnitude of 0.1 g to 0.9 g, reached a peak at 0.3 g and then decreased slowly. The scleraxis, tenogenic markers, and mRNA expression decreased at 0.05 g, 0.1 g, and 0.3 g, and significantly increased at 0.6 g and 0.9 g. Compared with the static group, the F-actin stress fibers of hPDLSCs became thicker and clearer following vibration. Conclusions The LMHF mechanical vibration promotes PDLSC osteogenic differentiation and implies the existence of a magnitude-dependent effect of vibration on determining PDLSC commitment to the osteoblast lineage. Changes in the cytoskeleton of hPDLSCs after vibration may be one of the mechanisms of the biological effects. PMID:26170859

Synchrotron Radiation and the Far-Infrared and Mid-Infrared Spectra of Ncncs

NASA Astrophysics Data System (ADS)

Winnewisser, Manfred; Winnewisser, Brenda P.; De Lucia, Frank C.; Tokaryk, Dennis; Ross, Stephen Cary; Billinghurst, Brant E.

2014-06-01

The large-amplitude in-plane bending vibration of NCNCS at 85 wn has a potential energy function which includes a barrier to linearity with a height of about 285 wn. The topology of the surface of the space defined by this two-dimensional potential function exhibits non-trivial monodromy. Therefore an energy/momentum map for a quantum system with its motion determined by such a potential takes the form of a lattice which contains a defect associated with the top of the barrier. In NCNCS, the wavenumber values of the fundamental vibrational excitation and the barrier height mean that easily accessible energy levels allow us to observe 3 bending vibrational levels below and 3 above the barrier, yet still below all of the other vibrational levels, allowing the study of all the levels in the neighborhood of the defect. In three measuring campaigns at the Canadian Light Source in May of the years 2011, 2012, and 2013 we have now obtained 8 of the 9 fundamental vibrational band systems of NCNCS in high resolution, in particular that of the large-amplitude bend in the FIR. So far only a-type spectra have been assigned. Thus we have now determined the Δvb = 1, and ΔKa = 0 vibrational intervals (using bent molecule notation) but do not yet have experimental values for either rotational ΔKa = +/- 1 intervals nor ro-vibrational Δvb = 1, ΔKa = +/- 1 intervals. In May of 2014 we will have our last measuring campaign and hope to observe the more elusive b-type transitions.

Isotopomer-selective spectra of a single intact H2O molecule in the Cs+(D2O)5H2O isotopologue: Going beyond pattern recognition to harvest the structural information encoded in vibrational spectra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolke, Conrad T.; Fournier, Joseph A.; Miliordos, Evangelos

We report the vibrational signatures of a single H2O water molecule occupying distinct sites of the hydration network in the Cs+(H2O)6 cluster. This is accomplished using isotopomer selective IR-IR hole-burning on the Cs+(D2O)5(H2O) clusters formed by gas-phase exchange of a single, intact H2O molecule for D2O in the Cs+(D2O)6 ion. The OH stretching pattern of the Cs+(H2O)6 isotopologue is accurately recovered by superposition of the isotopomer spectra, thus establishing that the H2O incorporation is random and that the OH stretching manifold is largely due to contributions from decoupled water molecules. This behavior enables a powerful new way to extract structuralmore » information from vibrational spectra of size-selected clusters by explicitly identifying the local environments responsible for specific infrared features. The Cs+(H2O)6 structure was unambiguously assigned to the 4.1.1 isomer (a homodromic water tetramer with two additional flanking water molecules) from the fact that its computed IR spectrum matches the observed overall pattern and recovers the embedded correlations in the two OH stretching bands of the water molecule in the Cs+(D2O)5(H2O) isotopomers. The 4.1.1 isomer is the lowest in energy among other candidate networks at advanced (e.g., CCSD(T)) levels of theoretical treatment after corrections for (anharmonic) zero-point energy (ZPE). With the structure in hand, we then explore the mechanical origin of the various band locations using a local electric field formalism. This approach promises to provide a transferrable scheme for the prediction of the OH stretching fundamentals displayed by water networks in close proximity to solute ions.« less

[Carpal canal ultrasound examination in patients with mild hand-arm vibration disease].

PubMed

Liu, Y Z; Ye, Z H; Yang, W L; Zhu, J X; Lu, Q J; Su, W L

2016-08-20

Objective: To investigate the clinical value of ultrasound examination of carpal canal structure in patients with mild hand-arm vibration disease. Methods: A total of 29 patients (58 wrists) with mild hand-arm vibration disease who were treated in Shenzhen Prevention and Treatment Center for Occupational Diseases from May to December, 2015 were enrolled as observation group, and 20 healthy volunteers (40 wrists) were enrolled as the control group. Color Doppler ultrasound was used to observe the morphology and echo of the median nerve in the carpal canal and 9 muscle tendons and transverse carpal ligament. The thickness of transverse carpal ligament and diameter of the median nerve at the level of the hamulus of hamate bone were measured, as well as the cross-sectional area of the median nerve at the level of pisiform bone. Results: In the 29 patients with hand-arm vibration disease patients in the observation group, 8 experienced entrapment of the median nerve in the carpal canal, among whom 5 had entrapment in both wrists; there were 13 wrists (23%) with nerve entrapment and 45 wrists (77%) without nerve entrapment. Compared with the control group, the patients with hand-arm vibration disease and nerve entrapment in the observation group showed significant thickening of the transverse carpal ligament at the level of the hamulus of hamate bone and a significant increase in the cross-sectional area of the median nerve at the level of pisiform bone ( P <0.05) , while there were no significant differences in the thickness of transverse carpal ligament at the level of the hamulus of hamate bone and the cross-sectional area of the median nerve at the level of pisiform bone ( t=- 9.397 and -4.385, both P >0.05) . Conclusion: Ultrasound examination can clearly show the radiological changes of carpal canal contents in patients with mild hand-arm vibration disease and has a certain diagnostic value in nerve damage in patients with hand-arm vibration disease.

Comparison of high-intensity sound and mechanical vibration for cleaning porous titanium cylinders fabricated using selective laser melting.

PubMed

Seiffert, Gary; Hopkins, Carl; Sutcliffe, Chris

2017-01-01

Orthopedic components, such as the acetabular cup in total hip joint replacement, can be fabricated using porous metals, such as titanium, and a number of processes, such as selective laser melting. The issue of how to effectively remove loose powder from the pores (residual powder) of such components has not been addressed in the literature. In this work, we investigated the feasibility of two processes, acoustic cleaning using high-intensity sound inside acoustic horns and mechanical vibration, to remove residual titanium powder from selective laser melting-fabricated cylinders. With acoustic cleaning, the amount of residual powder removed was not influenced by either the fundamental frequency of the horn used (75 vs. 230 Hz) or, for a given horn, the number of soundings (between 1 and 20). With mechanical vibration, the amount of residual powder removed was not influenced by the application time (10 vs. 20 s). Acoustic cleaning was found to be more reliable and effective in removal of residual powder than cleaning with mechanical vibration. It is concluded that acoustic cleaning using high-intensity sound has significant potential for use in the final preparation stages of porous metal orthopedic components. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 117-123, 2017. © 2015 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc.

Hydraulic elements in reduction of vibrations in mechanical systems

NASA Astrophysics Data System (ADS)

Białas, K.; Buchacz, A.

2017-08-01

This work presents non-classical method of design of mechanic systems with subsystem reducing vibrations. The purpose of this paper is also introduces synthesis of mechanic system with reducing vibrations understand as design of this type of systems. The synthesis may be applied to modify the already existing systems in order to achieve a desired result. Elements which reduce vibrations can be constructed with passive, semi-active or active components. These considerations systems have selected active items. A hallmark of active elements it is possible to change the parameters on time of these elements and their power from an external source. The implementation of active elements is very broad. These elements can be implemented through the use of components of electrical, pneumatic, hydraulic, etc. The system was consisted from mechanical and hydraulic elements. Hydraulic elements were used as subsystem reducing unwanted vibration of mechanical system. Hydraulic elements can be realized in the form of hydraulic cylinder. In the case of an active vibration reduction in the form of hydraulic cylinder it is very important to find the corresponding values of hydraulic components. The values of these elements affect the frequency of vibrations of this sub-system which is related to the effective vibration reduction [7,11].

[A study on the thermographic diagnosis of vibration disease of tie-tamper operators in the Japanese National Railways].

PubMed

Hirahata, H

1984-01-01

There have been many studies of thermographic diagnosis of vibration disease, but few of them seem to have discussed tie-tamping machines as a cause. This study focuses on thermographic diagnosis of vibration disease in tie-tamper operators of the Japanese National Railways. In the diagnosis the subject's both hands were immersed in water at 10 degrees C for 3 minutes before being examined. Variables such as season, age, type of vibration tool used and total operating time were considered. These were selected as outside variables and thermographic results as dependent variables, in Quantification Method II. Season and confirmation of vibration disease were found to have a relationship to thermographic scaling, but no such relationship was found for age, type of vibration tool used, or total operating time. A cross-analysis of variables confirmed the relationship with season, and revealed that there were fewer confirmed cases of vibration disease in spring and summer than in fall and winter. It was finally concluded that thermographic analysis is more reliable in colder weather.

Structural Dynamics Testing of Advanced Stirling Convertor Components

NASA Technical Reports Server (NTRS)

Oriti, Salvatore M.; Williams, Zachary Douglas

2013-01-01

NASA Glenn Research Center has been supporting the development of Stirling energy conversion for use in space. Lockheed Martin has been contracted by the Department of Energy to design and fabricate flight-unit Advanced Stirling Radioisotope Generators, which utilize Sunpower, Inc., free-piston Advanced Stirling Convertors. The engineering unit generator has demonstrated conversion efficiency in excess of 20 percent, offering a significant improvement over existing radioisotope-fueled power systems. NASA Glenn has been supporting the development of this generator by developing the convertors through a technology development contract with Sunpower, and conducting research and experiments in a multitude of areas, such as high-temperature material properties, organics testing, and convertor-level extended operation. Since the generator must undergo launch, several launch simulation tests have also been performed at the convertor level. The standard test sequence for launch vibration exposure has consisted of workmanship and flight acceptance levels. Together, these exposures simulate what a flight convertor will experience. Recently, two supplementary tests were added to the launch vibration simulation activity. First was a vibration durability test of the convertor, intended to quantify the effect of vibration levels up to qualification level in both the lateral and axial directions. Second was qualification-level vibration of several heater heads with small oxide inclusions in the material. The goal of this test was to ascertain the effect of the inclusions on launch survivability to determine if the heater heads were suitable for flight.

Feedback damping of a microcantilever at room temperature to the minimum vibration amplitude limited by the noise level

PubMed Central

Kawamura, Y.; Kanegae, R.

2016-01-01

Cooling the vibration amplitude of a microcantilever as low as possible is important to improve the sensitivity and resolutions of various types of scanning type microscopes and sensors making use of it. When the vibration amplitude is controlled to be smaller using a feed back control system, it is known that the obtainable minimum amplitude of the vibration is limited by the floor noise level of the detection system. In this study, we demonstrated that the amplitude of the thermal vibration of a microcantilever was suppressed to be about 0.15 pmHz−1/2, which is the same value with the floor noise level, without the assistance of external cryogenic cooling. We think that one of the reason why we could reach the smaller amplitude at room temperature is due to stiffer spring constant of the lever, which leads to higher natural frequency and consequently lower floor noise level. The other reason is considered to be due to the increase in the laser power for the diagnostics, which lead to the decrease in the signal to noise ratio determined by the optical shot noise. PMID:27312284

Vibration and noise criteria used to evaluate environmental impacts of transportation projects on sensitive facilities

NASA Astrophysics Data System (ADS)

Busch, Todd; Gendreau, Michael; Amick, Hal

2005-08-01

The paper examines the methodologies and evaluation criteria advocated by the U.S. Federal Transit Administration (FTA) and Federal Rail Administration (FRA) used to determine whether or not a proposed alignment for a transportation project adversely impacts affected land uses, such as research & development and high-technology manufacturing. The criteria in question are applied as limits on vibration and noise at sensitive receiver locations. Both short-term construction and long-term transportation operations are typically considered, with the latter being the focus of this paper. A case study is presented of a proposed transit system that passes through four different soil zones, the operational characteristics that are required to generate a vibration level equal to the FTA/FRA advocated level of 65 VdB re: 1 micro-inch/sec, and the range of variability of the acceptability of the vibration conditions when considered in terms of third-octave bands compared to vibration criterion (VC) curves that are used as the design performance targets of vibration-sensitive facilities.

Hand-arm vibration syndrome from exposure to high-pressure hoses.

PubMed

Cooke, R; House, R; Lawson, I J; Pelmear, P L; Wills, M

2001-09-01

Hand-arm vibration syndrome has been reported in the literature to occur following exposure to vibration from the use of many tools, but to date there have been no case reports of its occurrence in workers who have used high-pressure hoses, alone or with other tools. To remedy this, the case histories of nine subjects (two without mixed exposure) examined in the UK and Canada are presented, together with their severity classified according to the Stockholm scales. Attention is drawn to the need to use multiple diagnostic tests to establish the diagnosis and the need to implement vibration isolation and damping methodologies, as and when feasible, with respect to hose nozzles in order to minimize the hazard. The ultimate goal for tool manufacturers, hygienists and engineers should be to reduce workplace vibration levels to meet national and international guidelines and legislation, including UK Health & Safety Executive guidelines and European Economic Community directives. The respective risk levels are presented, together with vibration measurements on hoses used by some of the cases.

Active damping of modal vibrations by force apportioning

NASA Technical Reports Server (NTRS)

Hallauer, W. L., Jr.

1980-01-01

Force apportioning, a method of active structural damping based on that used in modal vibration testing of isolating modes by multiple shaker excitation, was analyzed and numerically simulated. A distribution of as few forces as possible on the structure is chosen so as to maximally affect selected vibration modes while minimally exciting all other modes. The accuracy of numerical simulations of active damping, active damping of higher-frequency modes, and studies of imperfection sensitivity are discussed. The computer programs developed are described and possible refinements of the research are examined.

Semiconductor laser self-mixing micro-vibration measuring technology based on Hilbert transform

NASA Astrophysics Data System (ADS)

Tao, Yufeng; Wang, Ming; Xia, Wei

2016-06-01

A signal-processing synthesizing Wavelet transform and Hilbert transform is employed to measurement of uniform or non-uniform vibrations in self-mixing interferometer on semiconductor laser diode with quantum well. Background noise and fringe inclination are solved by decomposing effect, fringe counting is adopted to automatic determine decomposing level, a couple of exact quadrature signals are produced by Hilbert transform to extract vibration. The tempting potential of real-time measuring micro vibration with high accuracy and wide dynamic response bandwidth using proposed method is proven by both simulation and experiment. Advantages and error sources are presented as well. Main features of proposed semiconductor laser self-mixing interferometer are constant current supply, high resolution, simplest optical path and much higher tolerance to feedback level than existing self-mixing interferometers, which is competitive for non-contact vibration measurement.

Using monomer vibrational wavefunctions as contracted basis functions to compute rovibrational levels of an H2O-atom complex in full dimensionality.

PubMed

Wang, Xiao-Gang; Carrington, Tucker

2017-03-14

In this paper, we present new ideas for computing rovibrational energy levels of molecules composed of two components and apply them to H 2 O-Cl - . When both components are themselves molecules, Euler angles that specify their orientation with respect to an axis system attached to the inter-monomer vector are used as vibrational coordinates. For H 2 O-Cl - , there is only one set of Euler angles. Using Euler angles as intermolecular vibrational coordinates is advantageous because in many cases coupling between them and coordinates that describe the shape of the monomers is unimportant. The monomers are not assumed to be rigid. In the most efficient calculation, vibrational wavefunctions of the monomers are used as contracted basis functions. Energy levels are calculated using the Lanczos algorithm.

Using monomer vibrational wavefunctions as contracted basis functions to compute rovibrational levels of an H2O-atom complex in full dimensionality

NASA Astrophysics Data System (ADS)

Wang, Xiao-Gang; Carrington, Tucker

2017-03-01

In this paper, we present new ideas for computing rovibrational energy levels of molecules composed of two components and apply them to H2O-Cl-. When both components are themselves molecules, Euler angles that specify their orientation with respect to an axis system attached to the inter-monomer vector are used as vibrational coordinates. For H2O-Cl-, there is only one set of Euler angles. Using Euler angles as intermolecular vibrational coordinates is advantageous because in many cases coupling between them and coordinates that describe the shape of the monomers is unimportant. The monomers are not assumed to be rigid. In the most efficient calculation, vibrational wavefunctions of the monomers are used as contracted basis functions. Energy levels are calculated using the Lanczos algorithm.

Isotope separation by photoselective dissociative electron capture

DOEpatents

Stevens, C.G.

1978-08-29

Disclosed is a method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, [sup 235]UF[sub 6] is separated from a UF[sub 6] mixture by selective excitation followed by dissociative electron capture into [sup 235]UF[sub 5]- and F. 2 figs.

Isotope separation by photoselective dissociative electron capture

DOEpatents

Stevens, Charles G. [Pleasanton, CA

1978-08-29

A method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, .sup.235 UF.sub.6 is separated from a UF.sub.6 mixture by selective excitation followed by dissociative electron capture into .sup.235 UF.sub.5 - and F.

Evaluation of selected sidewalk pavement surfaces for vibration experienced by users of manual and powered wheelchairs.

PubMed

Cooper, Rory A; Wolf, Erik; Fitzgerald, Shirley G; Kellerher, Annmarie; Ammer, William; Boninger, Michael L; Cooper, Rosemarie

2004-01-01

Obstacles such as bumps, curb descents, and uneven driving surfaces cause vibrations that affect the wheelchair, and in turn, the wheelchair user. Chronic exposure can cause low-back pain, disk degeneration, and other harmful effects. Little research has been conducted to assess the vibrations experienced by wheelchair users. The purpose of this study was to conduct an evaluation of the vibration exposure during electric-powered wheelchair driving and mechanical energy requirements for manual wheelchair propulsion over selected sidewalk surfaces. The goal was to determine the criteria for a wheelchair-pedestrian access route that does not require excessive propulsive work or expose wheelchair users to potentially harmful vibrations. Ten unimpaired individuals participated in this study. Six sidewalk surfaces were tested. Measured variables included power of the acceleration per octave, mechanical work to propel over surfaces, peak acceleration, and frequency at which peak acceleration occurs. For both the manual and electric-powered wheelchair, at 1 m/s, significant differences were found in peak accelerations between the seat and footrest (P < 0.0001) and between the sidewalk surfaces (P = 0.004). The greatest risk for injury caused by shock and vibration exposure occurs at frequencies near the natural frequency of seated humans (4-15 Hz). The values for work required to propel over the surfaces tested were not statistically significantly different. Besides appearance and construction, the only distinguishing characteristic was surface roughness caused by the joints. When treating the poured concrete sidewalk as the standard, surfaces 2, 3, 5, and 6 compared most favorably in terms of vibration exposure, whereas surface 4 produced mixed results. Surfaces 2, 3, 5, and 6 yielded results that were similar to the poured concrete sidewalk and could be considered acceptable for wheelchair users. In conclusion, surfaces other than the traditional poured concrete can be used for pedestrian access routes without adding vibration exposure or reducing propulsion efficiency.

The effect of whole-body resonance vibration in a porcine model of spinal cord injury.

PubMed

Streijger, Femke; Lee, Jae H T; Chak, Jason; Dressler, Dan; Manouchehri, Neda; Okon, Elena B; Anderson, Lisa M; Melnyk, Angela D; Cripton, Peter A; Kwon, Brian K

2015-06-15

Whole-body vibration has been identified as a potential stressor to spinal cord injury (SCI) patients during pre-hospital transportation. However, the effect that such vibration has on the acutely injured spinal cord is largely unknown, particularly in the frequency domain of 5 Hz in which resonance of the spine occurs. The objective of the study was to investigate the consequences of resonance vibration on the injured spinal cord. Using our previously characterized porcine model of SCI, we subjected animals to resonance vibration (5.7±0.46 Hz) or no vibration for a period of 1.5 or 3.0 h. Locomotor function was assessed weekly and cerebrospinal fluid (CSF) samples were collected to assess different inflammatory and injury severity markers. Spinal cords were evaluated histologically to quantify preserved white and gray matter. No significant differences were found between groups for CSF levels of monocyte chemotactic protein-1, interleukin 6 (IL-6) and lL-8. Glial fibrillary acidic protein levels were lower in the resonance vibration group, compared with the non-vibrated control group. Spared white matter tissue was increased within the vibrated group at 7 d post-injury but this difference was not apparent at the 12-week time-point. No significant difference was observed in locomotor recovery following resonance vibration of the spine. Here, we demonstrate that exposure to resonance vibration for 1.5 or 3 h following SCI in our porcine model is not detrimental to the functional or histological outcomes. Our observation that a 3.0-h period of vibration at resonance frequency induces modest histological improvement at one week post-injury warrants further study.

Effect of Attitudinal, Situational and Demographic Factors on Annoyance Due to Environmental Vibration and Noise from Construction of a Light Rapid Transit System.

PubMed

Wong-McSweeney, Daniel; Woodcock, James; Waddington, David; Peris, Eulalia; Koziel, Zbigniew; Moorhouse, Andy; Redel-Macías, María Dolores

2016-12-14

The aim of this paper is to determine what non-exposure factors influence the relationship between vibration and noise exposure from the construction of a Light Rapid Transit (LRT) system and the annoyance of nearby residents. Noise and vibration from construction sites are known to annoy residents, with annoyance increasing as a function of the magnitude of the vibration and noise. There is not a strong correlation between exposure and levels of annoyance suggesting that factors not directly related to the exposure may have an influence. A range of attitudinal, situational and demographic factors are investigated with the aim of understanding the wide variation in annoyance for a given vibration exposure. A face-to-face survey of residents ( n = 350) near three sites of LRT construction was conducted, and responses were compared to semi-empirical estimates of the internal vibration within the buildings. It was found that annoyance responses due to vibration were strongly influenced by two attitudinal variables, concern about property damage and sensitivity to vibration. Age, ownership of the property and the visibility of the construction site were also important factors. Gender, time at home and expectation of future levels of vibration had much less influence. Due to the measurement methods used, it was not possible to separate out the effects of noise and vibration on annoyance; as such, this paper focusses on annoyance due to vibration exposure. This work concludes that for the most cost-effective reduction of the impact of construction vibration and noise on the annoyance felt by a community, policies should consider attitudinal factors.

Effect of Attitudinal, Situational and Demographic Factors on Annoyance Due to Environmental Vibration and Noise from Construction of a Light Rapid Transit System

PubMed Central

Wong-McSweeney, Daniel; Woodcock, James; Waddington, David; Peris, Eulalia; Koziel, Zbigniew; Moorhouse, Andy; Redel-Macías, María Dolores

2016-01-01

The aim of this paper is to determine what non-exposure factors influence the relationship between vibration and noise exposure from the construction of a Light Rapid Transit (LRT) system and the annoyance of nearby residents. Noise and vibration from construction sites are known to annoy residents, with annoyance increasing as a function of the magnitude of the vibration and noise. There is not a strong correlation between exposure and levels of annoyance suggesting that factors not directly related to the exposure may have an influence. A range of attitudinal, situational and demographic factors are investigated with the aim of understanding the wide variation in annoyance for a given vibration exposure. A face-to-face survey of residents (n = 350) near three sites of LRT construction was conducted, and responses were compared to semi-empirical estimates of the internal vibration within the buildings. It was found that annoyance responses due to vibration were strongly influenced by two attitudinal variables, concern about property damage and sensitivity to vibration. Age, ownership of the property and the visibility of the construction site were also important factors. Gender, time at home and expectation of future levels of vibration had much less influence. Due to the measurement methods used, it was not possible to separate out the effects of noise and vibration on annoyance; as such, this paper focusses on annoyance due to vibration exposure. This work concludes that for the most cost-effective reduction of the impact of construction vibration and noise on the annoyance felt by a community, policies should consider attitudinal factors. PMID:27983662

The effect of whole body vibration on fracture healing - a systematic review.

PubMed

Wang, J; Leung, K S; Chow, S K; Cheung, W H

2017-09-07

This systematic review examines the efficacy and safety of whole body vibration (WBV) on fracture healing. A systematic literature search was conducted with relevant keywords in PubMed and Embase, independently, by two reviewers. Original animal and clinical studies about WBV effects on fracture healing with available full-text and written in English were included. Information was extracted from the included studies for review. In total, 19 articles about pre-clinical studies were selected. Various vibration regimes are reported; of those, the frequencies of 35 Hz and 50 Hz show better results than others. Most of the studies show positive effects on fracture healing after vibration treatment and the responses to vibration are better in ovariectomised (OVX) animals than non-OVX ones. However, several studies provide insufficient evidence to support an improvement of fracture healing after vibration and one study even reports disruption of fracture healing after vibration. In three studies, vibration results in positive effects on angiogenesis at the fracture site and surrounding muscles during fracture healing. No serious complications or side effects of vibration are found in these studies. WBV is suggested to be beneficial in improving fracture healing in animals without safety problem reported. In order to apply vibration on fractured patients, more well-designed randomised controlled clinical trials are needed to examine its efficacy, regimes and safety.

Local Environment and Interactions of Liquid and Solid Interfaces Revealed by Spectral Line Shape of Surface Selective Nonlinear Vibrational Probe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Shun-Li; Fu, Li; Chase, Zizwe A.

Vibrational spectral lineshape contains important detailed information of molecular vibration and reports its specific interactions and couplings to its local environment. In this work, recently developed sub-1 cm-1 high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS) was used to measure the -C≡N stretch vibration in the 4-n-octyl-4’-cyanobiphenyl (8CB) Langmuir or Langmuir-Blodgett (LB) monolayer as a unique vibrational probe, and the spectral lineshape analysis revealed the local environment and interactions at the air/water, air/glass, air/calcium fluoride and air/-quartz interfaces for the first time. The 8CB Langmuir or LB film is uniform and the vibrational spectral lineshape of its -C≡N group hasmore » been well characterized, making it a good choice as the surface vibrational probe. Lineshape analysis of the 8CB -C≡N stretch SFG vibrational spectra suggests the coherent vibrational dynamics and the structural and dynamic inhomogeneity of the -C≡N group at each interface are uniquely different. In addition, it is also found that there are significantly different roles for water molecules in the LB films on different substrate surfaces. These results demonstrated the novel capabilities of the surface nonlinear spectroscopy in characterization and in understanding the specific structures and chemical interactions at the liquid and solid interfaces in general.« less

Contribution of individual components of a job cycle on overall severity of whole-body vibration exposure: a study in Indian mines.

PubMed

Mandal, Bibhuti B; Mansfield, Neil J

2016-01-01

Drivers of earth-moving machines are exposed to whole-body vibration (WBV). In mining operations there can be a combination of relatively high magnitudes of vibration and long exposure times. Effective risk mitigation requires understanding of the main aspects of a task that pose a hazard to health. There are very few published studies of WBV exposure from India. This paper reports on a study that considered the contribution of the component phases of dumper operations, on the overall vibration exposure of the drivers. It shows that vibration magnitudes are relatively high, and that haulage tasks are the main contributor to the exposure. It is recommended that driver speed, haul road surfaces and vehicle maintenance/selection are optimized to ensure minimization of vibration. If this is not sufficient, operation times might need to be reduced in order to ensure that the health guidance caution zone from Standard No. ISO 2631-1:1997 is not exceeded.

A New Large Vibration Test Facility Concept for the James Webb Space Telescope

NASA Technical Reports Server (NTRS)

Ross, Brian P.; Johnson, Eric L.; Hoksbergen, Joel; Lund, Doug

2014-01-01

The James Webb Space Telescope consists of three main components, the Integrated Science Instrument Module (ISIM) Element, the Optical Telescope Element (OTE), and the Spacecraft Element. The ISIM and OTE are being assembled at the National Aeronautics and Space Administration's Goddard Spaceflight Center (GSFC). The combined OTE and ISIM Elements, called OTIS, will undergo sine vibration testing before leaving Goddard. OTIS is the largest payload ever tested at Goddard and the existing GSFC vibration facilities are incapable of performing a sine vibration test of the OTIS payload. As a result, a new large vibration test facility is being designed. The new facility will consist of a vertical system with a guided head expander and a horizontal system with a hydrostatic slip table. The project is currently in the final design phase with installation to begin in early 2015 and the facility is expected to be operational by late 2015. This paper will describe the unique requirements for a new large vibration test facility and present the selected final design concepts.

The Evolution of Ih C_60 Vibrational Modes in Planar Polymerized C_60.

NASA Astrophysics Data System (ADS)

Adams, G. B.; Page, J. B.

2001-03-01

We have used first-principles local-orbital-based molecular dynamics(O.F. Sankey and D.J. Niklewski, Phys. Rev. B40), 3979 (1989). to simulate a wide variety of planar polymers of C_60, including the orthorhombic (O), tetrahedral (T), and rhombohedral (R) polymers which have been reported experimentally. It has been customary to assume that the vibrational modes of the polymers are moderately perturbed Ih C_60 vibrational modes.(See, for example V.A. Davydov et al.), Phys. Rev. B61, 11936 (2000) or V.C. Long et al., Phys. Rev. B 61, 13191 (2000). To test this assumption, we have expanded the polymer vibrational eigenvectors in the eigenvectors of Ih C_60, thus determining quantitatively the percentage contribution of each Ih C_60 mode to each polymer vibrational mode. We find that for many polymer modes the assumption is not justified. We report our results for selected Raman- and IR-active vibrational modes of the observed polymers.

Research on the design of fixture for motor vibration test

NASA Astrophysics Data System (ADS)

Shen, W. X.; Ma, W. S.; Zhang, L. W.

2018-03-01

The vibration reliability of the new energy automobile motor plays a very important role in driving safety, so it is very important to test the vibration durability of the motor. In the vibration test process, the fixture is very important, simulated road spectrum signal vibration can be transmitted without distortion to the motor through the fixture, fixture design directly affect the result of vibration endurance test. On the basis of new energy electric vehicle motor concrete structure, Two fixture design and fixture installation schemes for lateral cantilever type and base bearing type are put forward in this article, the selection of material, weighting process, middle alignment process and manufacturing process are summarized.The modal analysis and frequency response calculation of the fixture are carried out in this design, combine with influence caused by fixture height and structure profile on response frequency, the response frequency of each order of the fixture is calculated, then ultimately achieve the purpose of guiding the design.

Effect of vibration frequency on biopsy needle insertion force.

PubMed

Tan, Lei; Qin, Xuemei; Zhang, Qinhe; Zhang, Hongcai; Dong, Hongjian; Guo, Tuodang; Liu, Guowei

2017-05-01

Needle insertion is critical in many clinical medicine procedures, such as biopsy, brachytherapy, and injection therapy. A platform with two degrees of freedom was set up to study the effect of vibration frequency on needle insertion force. The gel phantom deformation at the needle cutting edge and the Voigt model are utilized to develop a dynamic model to explain the relationship between the insertion force and needle-tip velocity. The accuracy of this model was verified by performing needle insertions into phantom gel. The effect of vibration on insertion force can be explained as the vibration increasing the needle-tip velocity and subsequently increasing the insertion force. In a series of needle insertion experiments with different vibration frequencies, the peak forces were selected for comparison to explore the effect of vibration frequency on needle insertion force. The experimental results indicate that the insertion force at 500Hz increases up to 17.9% compared with the force at 50Hz. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Non-planar vibrations of slightly curved pipes conveying fluid in simple and combination parametric resonances

NASA Astrophysics Data System (ADS)

Czerwiński, Andrzej; Łuczko, Jan

2018-01-01

The paper summarises the experimental investigations and numerical simulations of non-planar parametric vibrations of a statically deformed pipe. Underpinning the theoretical analysis is a 3D dynamic model of curved pipe. The pipe motion is governed by four non-linear partial differential equations with periodically varying coefficients. The Galerkin method was applied, the shape function being that governing the beam's natural vibrations. Experiments were conducted in the range of simple and combination parametric resonances, evidencing the possibility of in-plane and out-of-plane vibrations as well as fully non-planar vibrations in the combination resonance range. It is demonstrated that sub-harmonic and quasi-periodic vibrations are likely to be excited. The method suggested allows the spatial modes to be determined basing on results registered at selected points in the pipe. Results are summarised in the form of time histories, phase trajectory plots and spectral diagrams. Dedicated video materials give us a better insight into the investigated phenomena.

Noise emissions and building structural vibration levels from the Supersonic Concorde and subsconic turbojet aircraft

DOT National Transportation Integrated Search

1975-03-01

Noise emissions and building structural vibration levels were measured during landing and take off operations of the Anglo/French supersonic aircraft (Concorde) and from some conventional subsonic turbojet aircraft. Measurements were made at both the...

Ground test for vibration control demonstrator

NASA Astrophysics Data System (ADS)

Meyer, C.; Prodigue, J.; Broux, G.; Cantinaud, O.; Poussot-Vassal, C.

2016-09-01

In the objective of maximizing comfort in Falcon jets, Dassault Aviation is developing an innovative vibration control technology. Vibrations of the structure are measured at several locations and sent to a dedicated high performance vibration control computer. Control laws are implemented in this computer to analyse the vibrations in real time, and then elaborate orders sent to the existing control surfaces to counteract vibrations. After detailing the technology principles, this paper focuses on the vibration control ground demonstration that was performed by Dassault Aviation in May 2015 on Falcon 7X business jet. The goal of this test was to attenuate vibrations resulting from fixed forced excitation delivered by shakers. The ground test demonstrated the capability to implement an efficient closed-loop vibration control with a significant vibration level reduction and validated the vibration control law design methodology. This successful ground test was a prerequisite before the flight test demonstration that is now being prepared. This study has been partly supported by the JTI CleanSky SFWA-ITD.

Observations of the high vibrational levels of the B ' ' B ¯ 1 Σu + state of H2

NASA Astrophysics Data System (ADS)

Chartrand, A. M.; Duan, W.; Ekey, R. C.; McCormack, E. F.

2016-01-01

Double-resonance laser spectroscopy via the E F 1 Σg + , v ' = 6 , J ' = 0 -2 state was used to probe the high vibrational levels of the B ' ' B ¯ 1 Σu + state of molecular hydrogen. Resonantly enhanced multiphoton ionization spectra were recorded by detecting ion production as a function of energy using a time of flight mass spectrometer. New measurements of energies for the v = 51-66 levels for the B ' ' B ¯ state of H2 are reported, which, taken with previous results, span the v = 46-69 vibrational levels. Results for energy levels are compared to theoretical close-coupled calculations [L. Wolniewicz, T. Orlikowski, and G. Staszewska, J. Mol. Spectrosc. 238, 118-126 (2006)]. The average difference between the 84 measured energies and calculated energies is -3.8 cm-1 with a standard deviation of 5.3 cm-1. This level of agreement showcases the success of the theoretical calculations in accounting for the strong rovibronic mixing of the 1 Σu + and 1 Πu + states. Due to the ion-pair character of the outer well, the observed energies of the vibrational levels below the third dissociation limit smoothly connect with previously observed energies of ion-pair states above this limit. The results provide an opportunity for testing a heavy Rydberg multi-channel quantum defect analysis of the high vibrational states below the third dissociation limit.

System level mechanical testing of the Clementine spacecraft

NASA Technical Reports Server (NTRS)

Haughton, James; Hauser, Joseph; Raynor, William; Lynn, Peter

1994-01-01

This paper discusses the system level structural testing that was performed to qualify the Clementine Spacecraft for flight. These tests included spin balance, combined acoustic and axial random vibration, lateral random vibration, quasi-static loads, pyrotechnic shock, modal survey and on-orbit jitter simulation. Some innovative aspects of this effort were: the simultaneously combined acoustic and random vibration test; the mass loaded interface modal survey test; and the techniques used to assess how operating on board mechanisms and thrusters affect sensor vision.

Data on the noise vibrations of modern traction locomotives. [auditory effects on diesel engine operators

NASA Technical Reports Server (NTRS)

Paslaru, V.; Popescu, A.; Vrasti, R.

1974-01-01

A survey is presented of data on noise and vibration sources in modern locomotives and their influence on engine drivers. An attempt is made hierarchize noise and vibration sources in terms of importance and to correlate the noise level with the influence of noise on the engine drivers' organ of hearing. Some possible recommendations are outlined for reducing the level of these noxae in order to improve the acoustic comfort of engine drivers.

Stress-strain state of the structure in the service area of underground railway

NASA Astrophysics Data System (ADS)

Barabash, M.; Bashinsky, Y.; Korjakins, A.

2017-10-01

The paper focuses on numerical study how vibration due to underground trains influences the load-bearing building structures. Diagrams of vibration levels for monolithic floor slab depending on frequency are obtained. Levels of vibrations on floor slabs and columns are measured. The simulation of dynamic load from underground railway onto load-bearing building structures is presented as an example with account of load transmission through the soil. Recommendations for generation of design model in dynamic analysis of structure are provided.

Acceleration of a ground-state reaction by selective femtosecond-infrared-laser-pulse excitation

NASA Astrophysics Data System (ADS)

Stensitzki, Till; Yang, Yang; Kozich, Valeri; Ahmed, Ashour A.; Kössl, Florian; Kühn, Oliver; Heyne, Karsten

2018-02-01

Infrared (IR) excitation of vibrations that participate in the reaction coordinate of an otherwise thermally driven chemical reaction are believed to lead to its acceleration. Attempts at the practical realization of this concept have been hampered so far by competing processes leading to sample heating. Here we demonstrate, using femtosecond IR-pump IR-probe experiments, the acceleration of urethane and polyurethane formation due to vibrational excitation of the reactants for 1:1 mixtures of phenylisocyanate and cyclohexanol, and toluene-2,4-diisocyanate and 2,2,2-trichloroethane-1,1-diol, respectively. We measured reaction rate changes upon selective vibrational excitation with negligible heating of the sample and observed an increase of the reaction rate up to 24%. The observation is rationalized using reactant and transition-state structures obtained from quantum chemical calculations. We subsequently used IR-driven reaction acceleration to write a polyurethane square on sample windows using a femtosecond IR pulse.

Research on Aero-Thermodynamic Distortion Induced Structural Dynamic Response of Multistage Compressor Blading

DTIC Science & Technology

1992-03-01

of realistic reduced frequency values for the ftost time. 14. SUIUECT TEIEMS IS. NUMBER OF PAGES Unsteady Aerodynamic, 143 Flow Induced Vibrations 16...Flat Plate APPENDIX X. Prediction of Turbulence Generated Random Vibrational 106 Response of Turbomachinery Blading 3 APPENDIX XI. Viscous Oscillating...failure is fatigue caused by vibrations at levels exceeding3 material endurance limits. These vibrations occur when a periodic forcing function, with

Building vibrations induced by noise from rotorcraft and propeller aircraft flyovers

NASA Technical Reports Server (NTRS)

Shepherd, Kevin P.; Hubbard, Harvey H.

1992-01-01

Noise and building vibrations were measured for a series of helicopter and propeller-driven aircraft flyovers at WFF during May 1978. The building response data are compared with similar data acquired earlier at sites near Dulles and Kennedy Airports for operation of commercial jet transports, including the Concorde supersonic transport. Results show that noise-induced vibration levels in windows and walls are directly proportional to sound pressure level and that for a given noise level, the acceleration levels induced by a helicopter or a propeller-driven aircraft flyover cannot be distinguished from the acceleration levels induced by a commercial jet transport flyover. Noise-induced building acceleration levels were found to be lower than those levels which might be expected to cause structural damage and were also lower than some acceleration levels induced by such common domestic events as closing windows and doors.

DDD: Dynamic Database for Diatomics

NASA Technical Reports Server (NTRS)

Schwenke, David

2004-01-01

We have developed as web-based database containing spectra of diatomic moiecuies. All data is computed from first principles, and if a user requests data for a molecule/ion that is not in the database, new calculations are automatically carried out on that species. Rotational, vibrational, and electronic transitions are included. Different levels of accuracy can be selected from qualitatively correct to the best calculations that can be carried out. The user can view and modify spectroscopic constants, view potential energy curves, download detailed high temperature linelists, or view synthetic spectra.

Compatibility of the Space Station Freedom life sciences research centrifuge with microgravity requirements

NASA Technical Reports Server (NTRS)

Hasha, Martin D.

1990-01-01

NASA is developing a Life Sciences Centrifuge Facility for Space Station Freedom. In includes a 2.5-meter artificial gravity Bioresearch Centrifuge (BC), which is perhaps the most critical single element in the life sciences space research program. It rotates continuously at precise selectable rates, and utilizes advanced reliable technologies to reduce vibrations. Three disturbance types are analyzed using a current Space Station Freedom dynamic model in the 0.0 to 5.0 Hz range: sinusoidal, random, and transient. Results show that with proper selection of proven design techniques, BC vibrations are compatible with requirements.

Laser isotope separation by multiple photon absorption

DOEpatents

Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

1987-01-01

Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

Laser isotope separation by multiple photon absorption

DOEpatents

Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

1977-01-01

Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, in the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

A micro-vibration generated method for testing the imaging quality on ground of space remote sensing

NASA Astrophysics Data System (ADS)

Gu, Yingying; Wang, Li; Wu, Qingwen

2018-03-01

In this paper, a novel method is proposed, which can simulate satellite platform micro-vibration and test the impact of satellite micro-vibration on imaging quality of space optical remote sensor on ground. The method can generate micro-vibration of satellite platform in orbit from vibrational degrees of freedom, spectrum, magnitude, and coupling path. Experiment results show that the relative error of acceleration control is within 7%, in frequencies from 7Hz to 40Hz. Utilizing this method, the system level test about the micro-vibration impact on imaging quality of space optical remote sensor can be realized. This method will have an important applications in testing micro-vibration tolerance margin of optical remote sensor, verifying vibration isolation and suppression performance of optical remote sensor, exploring the principle of micro-vibration impact on imaging quality of optical remote sensor.

Finite Element Analysis and Experimental Study on Elbow Vibration Transmission Characteristics

NASA Astrophysics Data System (ADS)

Qing-shan, Dai; Zhen-hai, Zhang; Shi-jian, Zhu

2017-11-01

Pipeline system vibration is one of the significant factors leading to the vibration and noise of vessel. Elbow is widely used in the pipeline system. However, the researches about vibration of elbow are little, and there is no systematic study. In this research, we firstly analysed the relationship between elbow vibration transmission characteristics and bending radius by ABAQUS finite element simulation. Then, we conducted the further vibration test to observe the vibration transmission characteristics of different elbows which have the same diameter and different bending radius under different flow velocity. The results of simulation calculation and experiment both showed that the vibration acceleration levels of the pipeline system decreased with the increase of bending radius of the elbow, which was beneficial to reduce the transmission of vibration in the pipeline system. The results could be used as reference for further studies and designs for the low noise installation of pipeline system.

Erratum: "Low vibration laboratory with a single-stage vibration isolation for microscopy applications" [Rev. Sci. Instrum. 88, 023703 (2017)

NASA Astrophysics Data System (ADS)

Voigtländer, Bert; Coenen, Peter; Cherepanov, Vasily; Borgens, Peter; Duden, Thomas; Tautz, F. Stefan

2018-01-01

The construction and the vibrational performance of a low vibration laboratory for microscopy applications comprising a 100 ton floating foundation supported by passive pneumatic isolators (air springs), which rest themselves on a 200 ton solid base plate is discussed. The optimization of the air spring system lead to a vibration level on the floating floor below that induced by an acceleration of 10 ng for most frequencies. Additional acoustic and electromagnetic isolation is accomplished by a room-in-room concept.

Quantum dynamics study on the binding of a positron to vibrationally excited states of hydrogen cyanide molecule

NASA Astrophysics Data System (ADS)

Takayanagi, Toshiyuki; Suzuki, Kento; Yoshida, Takahiko; Kita, Yukiumi; Tachikawa, Masanori

2017-05-01

We present computational results of vibrationally enhanced positron annihilation in the e+ + HCN/DCN collisions within a local complex potential model. Vibrationally elastic and inelastic cross sections and effective annihilation rates were calculated by solving a time-dependent complex-potential Schrödinger equation under the ab initio potential energy surface for the positron attached HCN molecule, [HCN; e+], with multi-component configuration interaction level (Kita and Tachikawa, 2014). We discuss the effect of vibrational excitation on the positron affinities from the obtained vibrational resonance features.

One-dimensional cuts through multidimensional potential-energy surfaces by tunable x rays

NASA Astrophysics Data System (ADS)

Eckert, Sebastian; da Cruz, Vinícius Vaz; Gel'mukhanov, Faris; Ertan, Emelie; Ignatova, Nina; Polyutov, Sergey; Couto, Rafael C.; Fondell, Mattis; Dantz, Marcus; Kennedy, Brian; Schmitt, Thorsten; Pietzsch, Annette; Odelius, Michael; Föhlisch, Alexander

2018-05-01

The concept of the potential-energy surface (PES) and directional reaction coordinates is the backbone of our description of chemical reaction mechanisms. Although the eigenenergies of the nuclear Hamiltonian uniquely link a PES to its spectrum, this information is in general experimentally inaccessible in large polyatomic systems. This is due to (near) degenerate rovibrational levels across the parameter space of all degrees of freedom, which effectively forms a pseudospectrum given by the centers of gravity of groups of close-lying vibrational levels. We show here that resonant inelastic x-ray scattering (RIXS) constitutes an ideal probe for revealing one-dimensional cuts through the ground-state PES of molecular systems, even far away from the equilibrium geometry, where the independent-mode picture is broken. We strictly link the center of gravity of close-lying vibrational peaks in RIXS to a pseudospectrum which is shown to coincide with the eigenvalues of an effective one-dimensional Hamiltonian along the propagation coordinate of the core-excited wave packet. This concept, combined with directional and site selectivity of the core-excited states, allows us to experimentally extract cuts through the ground-state PES along three complementary directions for the showcase H2O molecule.

UHB demonstrator interior noise control flight tests and analysis

NASA Astrophysics Data System (ADS)

Simpson, M. A.; Druez, P. M.; Kimbrough, A. J.; Brock, M. P.; Burge, P. L.; Mathur, G. P.; Cannon, M. R.; Tran, B. N.

1989-10-01

The measurement and analysis of MD-UHB (McDonnell Douglas Ultra High Bypass) Demonstrator noise and vibration flight test data are described as they relate to passenger cabin noise. The analyses were done to investigate the interior noise characteristics of advanced turboprop aircraft with aft-mounted engines, and to study the effectiveness of selected noise control treatments in reducing passenger cabin noise. The UHB Demonstrator is an MD-80 test aircraft with the left JT8D engine replaced with a prototype UHB engine. For these tests, the UHB engine was a General Electric Unducted Fan, with either 8x8 or 10x8 counter-rotating propeller configurations. Interior noise level characteristics were studied for several altitudes and speeds, with emphasis on high altitude (35,000 ft), high speed (0.75 Mach) cruise conditions. The effectiveness of several noise control treatments was evaluated based on cabin noise measurements. The important airborne and structureborne transmission paths were identified for both tonal and broadband sources using the results of a sound intensity survey, exterior and interior noise and vibration data, and partial coherence analysis techniques. Estimates of the turbulent boundary layer pressure wavenumber-frequency spectrum were made, based on measured fuselage noise levels.

UHB demonstrator interior noise control flight tests and analysis

NASA Technical Reports Server (NTRS)

Simpson, M. A.; Druez, P. M.; Kimbrough, A. J.; Brock, M. P.; Burge, P. L.; Mathur, G. P.; Cannon, M. R.; Tran, B. N.

1989-01-01

The measurement and analysis of MD-UHB (McDonnell Douglas Ultra High Bypass) Demonstrator noise and vibration flight test data are described as they relate to passenger cabin noise. The analyses were done to investigate the interior noise characteristics of advanced turboprop aircraft with aft-mounted engines, and to study the effectiveness of selected noise control treatments in reducing passenger cabin noise. The UHB Demonstrator is an MD-80 test aircraft with the left JT8D engine replaced with a prototype UHB engine. For these tests, the UHB engine was a General Electric Unducted Fan, with either 8x8 or 10x8 counter-rotating propeller configurations. Interior noise level characteristics were studied for several altitudes and speeds, with emphasis on high altitude (35,000 ft), high speed (0.75 Mach) cruise conditions. The effectiveness of several noise control treatments was evaluated based on cabin noise measurements. The important airborne and structureborne transmission paths were identified for both tonal and broadband sources using the results of a sound intensity survey, exterior and interior noise and vibration data, and partial coherence analysis techniques. Estimates of the turbulent boundary layer pressure wavenumber-frequency spectrum were made, based on measured fuselage noise levels.

Selecting seats for steel industry mobile machines based on seat effective amplitude transmissibility and comfort.

PubMed

Conrad, Leanne F; Oliver, Michele L; Jack, Robert J; Dickey, James P; Eger, Tammy R

2014-01-01

The purpose of this work was to help a steel industry partner select the most appropriate of three high end heavy equipment seats to retrofit a number of their heavy mobile machines used in the steel making process. The participants included 8 males (22.3 ± 2.0 yrs.) and 8 females (23.5 ± 1.8 yrs.) with no experience operating heavy mobile equipment. Previously recorded 6-DOF chassis acceleration data from a Pot Hauler (a machine which picks up and transports pots of slag) were used to extract six, 20 second representative profiles for implementation on a lab-based heavy machine simulator (6-DOF Parallel Robotics System Corporation robot). Subjects sat on three heavy equipment seats (BeGe7150, Grammar MSG 95G1721, and a 6801 Isringhausen with the seat pan cushion retrofitted with a Skydex cushion) mounted on the simulator. Each subject completed three trials for each combination of seat (n=3) and vibration profile (n=6). Chassis and operator/seat interface vibration were measured by 2, 6-DOF vibration transducers. Variables included Seat Effective Amplitude Transmissibility (SEAT) (X,Y,Z,Roll,Pitch,Yaw,6DOF Vector Sum) to determine if the seat was attenuating or amplifying the vibration, 6-degree of freedom (DOF) vibration total value weighted predicted comfort (Avc) (according to ISO 2631-1) and operator reported comfort (ORC). Factorial ANOVAs revealed significant differences (p < or = 0.05) between seats for all SEAT variables but different seats performed better than others depending on the axis. Significant differences between males and females were observed for SEAT in X,Y, and Pitch as well as for Avs. As expected there were significant differences between vibration profiles for all assessed variables. A number of interaction effects were observed, the most frequently occurring of which was between seat and vibration profile. Based upon the number of seat and vibration profile interactions, results suggest that a single seat is not suited for all tested conditions. However, SEAT values for all of the seats tested were extremely low (e.g., 6-DOF SEAT < 30%) indicating that all of the seats were capable of providing good vibration attenuation.

A Combined Probe-Molecule, Mössbauer, Nuclear Resonance Vibrational Spectroscopy, and Density Functional Theory Approach for Evaluation of Potential Iron Active Sites in an Oxygen Reduction Reaction Catalyst

DOE PAGES

Kneebone, Jared L.; Daifuku, Stephanie L.; Kehl, Jeffrey A.; ...

2017-07-06

While non-precious metal M-N-C (M = Fe or Co) catalysts have been developed that are effective for the oxygen reduction reaction in polymer electrolyte fuel cells, no consensus has yet been reached regarding the nature of the M sites in these heterogeneous catalysts that are responsible for reaction with dioxygen (O 2). While multiple studies have developed correlations between Fe distributions in as-prepared catalysts and ORR activity, the direct identification of sites reactive towards O 2 or O 2-analog molecules remains a significant challenge. In the present study, we demonstrate a new approach to identifying and characterizing potential Fe activemore » sites in complex ORR catalysts that combines an effective probe molecule (NO (g)) Mössbauer spectroscopy and nuclear resonance vibrational spectroscopy (NRVS) with density functional theory (DFT) calculations. Mössbauer spectroscopic studies demonstrate that NO (g) treatment of electrochemically reduced PANI-57Fe-C leads to selective reaction with only a sub-set of the Fe species present. Nuclear resonance vibrational spectroscopic studies identified new Fe-ligand vibrations associated with the site reactive towards NO (g). DFT calculations of vibrational properties of a small selection of previously proposed active site structures suggest that graphene zig-zag edge hosted Fe-N structures may be responsible for the observed vibrational behavior with NO (g) probe molecules. Moreover, such sites are likely also reactive to O 2, possibly serving as the ORR active sites in the synthesized materials.« less

A Combined Probe-Molecule, Mössbauer, Nuclear Resonance Vibrational Spectroscopy, and Density Functional Theory Approach for Evaluation of Potential Iron Active Sites in an Oxygen Reduction Reaction Catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kneebone, Jared L.; Daifuku, Stephanie L.; Kehl, Jeffrey A.

While non-precious metal M-N-C (M = Fe or Co) catalysts have been developed that are effective for the oxygen reduction reaction in polymer electrolyte fuel cells, no consensus has yet been reached regarding the nature of the M sites in these heterogeneous catalysts that are responsible for reaction with dioxygen (O 2). While multiple studies have developed correlations between Fe distributions in as-prepared catalysts and ORR activity, the direct identification of sites reactive towards O 2 or O 2-analog molecules remains a significant challenge. In the present study, we demonstrate a new approach to identifying and characterizing potential Fe activemore » sites in complex ORR catalysts that combines an effective probe molecule (NO (g)) Mössbauer spectroscopy and nuclear resonance vibrational spectroscopy (NRVS) with density functional theory (DFT) calculations. Mössbauer spectroscopic studies demonstrate that NO (g) treatment of electrochemically reduced PANI-57Fe-C leads to selective reaction with only a sub-set of the Fe species present. Nuclear resonance vibrational spectroscopic studies identified new Fe-ligand vibrations associated with the site reactive towards NO (g). DFT calculations of vibrational properties of a small selection of previously proposed active site structures suggest that graphene zig-zag edge hosted Fe-N structures may be responsible for the observed vibrational behavior with NO (g) probe molecules. Moreover, such sites are likely also reactive to O 2, possibly serving as the ORR active sites in the synthesized materials.« less

Windows in direct dissociative recombination cross sections

NASA Technical Reports Server (NTRS)

Guberman, Steven L.

1986-01-01

Model potential curves are used to show that large windows are present in direct dissociative-recombination cross sections from excited molecular-ion vibrational levels. The windows are due to the overlap of vibrational wave functions of the repulsive neutral states with the nodes of the ion vibrational wave function.

Muscular forearm activation in hand-grip tasks with superimposition of mechanical vibrations.

PubMed

Fattorini, L; Tirabasso, A; Lunghi, A; Di Giovanni, R; Sacco, F; Marchetti, E

2016-02-01

The purpose of this paper is to evaluate the muscular activation of the forearm, with or without vibration stimuli at different frequencies while performing a grip tasks of 45s at various level of exerted force. In 16 individuals, 9 females and 7 males, the surface electromyogram (EMG) of extensor carpi radialis longus and the flexor carpi ulnari muscles were assessed. At a short latency from onset EMG, RMS and the level of MU synchronization were assessed to evaluate the muscular adaptations. Whilst a trend of decay of EMG Median frequency (MDFd) was employed as an index of muscular fatigue. Muscular tasks consists of the grip of an instrumented handle at a force level of 20%, 30%, 40%, 60% of the maximum voluntary force. Vibration was supplied by a shaker to the hand in mono-frequential waves at 20, 30, 33 and 40Hz. In relation to EMG, RMS and MU synchronization, the muscular activation does not seem to change with the superimposition of the mechanical vibrations, on the contrary a lower MDFd was observed at 33Hz than in absence of vibration. This suggests an early muscular fatigue induced by vibration due to the fact that 33Hz is a resonance frequency for the hand-arm system. Copyright © 2015 Elsevier Ltd. All rights reserved.

Coherent coupling of molecular resonators with a microcavity mode

NASA Astrophysics Data System (ADS)

Shalabney, A.; George, J.; Hutchison, J.; Pupillo, G.; Genet, C.; Ebbesen, T. W.

2015-01-01

The optical hybridization of the electronic states in strongly coupled molecule-cavity systems have revealed unique properties, such as lasing, room temperature polariton condensation and the modification of excited electronic landscapes involved in molecular isomerization. Here we show that molecular vibrational modes of the electronic ground state can also be coherently coupled with a microcavity mode at room temperature, given the low vibrational thermal occupation factors associated with molecular vibrations, and the collective coupling of a large ensemble of molecules immersed within the cavity-mode volume. This enables the enhancement of the collective Rabi-exchange rate with respect to the single-oscillator coupling strength. The possibility of inducing large shifts in the vibrational frequency of selected molecular bonds should have immediate consequences for chemistry.

Hyperspectral vibrational photoacoustic imaging of lipids and collagen

NASA Astrophysics Data System (ADS)

Wang, Pu; Wang, Ping; Wang, Han-Wei; Cheng, Ji-Xin

2012-02-01

The recently developed vibrational photoacoustic (VPA) microscopy allows bond-selective imaging of deep tissues by taking advantage of intrinsic contrast from harmonic vibration of C-H bonds. Due to the spectral similarity of molecules in the overtone vibration region, the compositional information is not available from VPA images acquired by single wavelength excitation. Here we demonstrate that lipids and collagen, two critical markers in many kinds of diseases, can be distinguished by hyperspectral VPA imaging. A phantom consisted of rat tail tendon (collagen) and fat tissue (lipids) was constructed. Wavelengths between 1650 and 1850 nm were scanned to excite the first overtone/combination vibration of C-H bond. B-scan hyperspectral VPA images, in which each pixel contains a spectrum, was analyzed by a Multivariate Curve Resolution - Alternating Least Squares (MCR-ALS) algorism to recover the spatial distribution of two chemical components in the phantom.

Modelling of Rail Vehicles and Track for Calculation of Ground-Vibration Transmission Into Buildings

NASA Astrophysics Data System (ADS)

Hunt, H. E. M.

1996-05-01

A methodology for the calculation of vibration transmission from railways into buildings is presented. The method permits existing models of railway vehicles and track to be incorporated and it has application to any model of vibration transmission through the ground. Special attention is paid to the relative phasing between adjacent axle-force inputs to the rail, so that vibration transmission may be calculated as a random process. The vehicle-track model is used in conjunction with a building model of infinite length. The tracking and building are infinite and parallel to each other and forces applied are statistically stationary in space so that vibration levels at any two points along the building are the same. The methodology is two-dimensional for the purpose of application of random process theory, but fully three-dimensional for calculation of vibration transmission from the track and through the ground into the foundations of the building. The computational efficiency of the method will interest engineers faced with the task of reducing vibration levels in buildings. It is possible to assess the relative merits of using rail pads, under-sleeper pads, ballast mats, floating-slab track or base isolation for particular applications.

State resolved vibrational relaxation modeling for strongly nonequilibrium flows

NASA Astrophysics Data System (ADS)

Boyd, Iain D.; Josyula, Eswar

2011-05-01

Vibrational relaxation is an important physical process in hypersonic flows. Activation of the vibrational mode affects the fundamental thermodynamic properties and finite rate relaxation can reduce the degree of dissociation of a gas. Low fidelity models of vibrational activation employ a relaxation time to capture the process at a macroscopic level. High fidelity, state-resolved models have been developed for use in continuum gas dynamics simulations based on computational fluid dynamics (CFD). By comparison, such models are not as common for use with the direct simulation Monte Carlo (DSMC) method. In this study, a high fidelity, state-resolved vibrational relaxation model is developed for the DSMC technique. The model is based on the forced harmonic oscillator approach in which multi-quantum transitions may become dominant at high temperature. Results obtained for integrated rate coefficients from the DSMC model are consistent with the corresponding CFD model. Comparison of relaxation results obtained with the high-fidelity DSMC model shows significantly less excitation of upper vibrational levels in comparison to the standard, lower fidelity DSMC vibrational relaxation model. Application of the new DSMC model to a Mach 7 normal shock wave in carbon monoxide provides better agreement with experimental measurements than the standard DSMC relaxation model.

Evaluation of ride quality prediction methods for helicopter interior noise and vibration environments

NASA Technical Reports Server (NTRS)

Leatherwood, J. D.; Clevenson, S. A.; Hollenbaugh, D. D.

1984-01-01

The results of a simulator study conducted to compare and validate various ride quality prediction methods for use in assessing passenger/crew ride comfort within helicopters are presented. Included are results quantifying 35 helicopter pilots discomfort responses to helicopter interior noise and vibration typical of routine flights, assessment of various ride quality metrics including the NASA ride comfort model, and examination of possible criteria approaches. Results of the study indicated that crew discomfort results from a complex interaction between vibration and interior noise. Overall measures such as weighted or unweighted root-mean-square acceleration level and A-weighted noise level were not good predictors of discomfort. Accurate prediction required a metric incorporating the interactive effects of both noise and vibration. The best metric for predicting crew comfort to the combined noise and vibration environment was the NASA discomfort index.

Calculation of the vibration-rotational transition intensities of water molecules trapped in an argon matrix: stretching O-H vibrations spectral region

NASA Astrophysics Data System (ADS)

Pitsevich, George; Shalamberidze, Elena; Malevich, Alex; Sablinskas, Valdas; Balevicius, Vytautas; Pettersson, Lars G. M.

2017-10-01

The frequencies and intensities of vibration-rotational transitions of water molecules in an argon matrix were calculated for temperatures of 6 and 30 K. The rigid asymmetric top approximation was used with available literature values of the effective rotational constants in the ground and excited vibrational states. The calculations were carried out by taking into account the existence of a non-equilibrium population distribution between the rotational levels of ortho- and para-water isomers. It was assumed that the temperature relaxation of the population of rotational levels is independent of the ortho- and para-isomers. Comparison of the results of the theoretical calculations with experimental literature data shows good agreement for the majority of the rotational structure lines for symmetric and antisymmetric stretching vibrations both in the frequency values and in the values of the relative intensities.

Analyzing wind turbine flow interaction through vibration data

NASA Astrophysics Data System (ADS)

Castellani, Francesco; D'Elia, Gianluca; Astolfi, Davide; Mucchi, Emiliano; Giorgio, Dalpiaz; Terzi, Ludovico

2016-09-01

Wind turbines commonly undergo non-stationary flow and, not rarely, even rather extreme phenomena. In particular, rough terrains represent a challenging testing ground, because of the combination of terrain-driven flow and wakes. It is therefore crucial to assess the impact of dynamic loads on the turbines. In this work, tower and drive-train vibrations are analyzed, from a subcluster of four turbines of a wind farm sited in a very complex terrain. The main outcome of the study is that it is possible to start from the analysis of wind conditions and interpret how wakes manifest in the vibrations of the turbines, both at structural level (tower vibrations) and at the drive-train level. This wind to gear approach therefore allows to build a connection between a flow phenomenon and a mechanical phenomenon (vibrations) and can be precious to assess loads in different working conditions.

Towards fundamental understanding of ultracold KRb

NASA Astrophysics Data System (ADS)

Kotochigova, Svetlana

2009-05-01

The recent formation of ultracold KRb molecules in their absolute rovibrational ground state [1] has created great promise for study of collective phenomena that rely on the long-range interactions between polar molecules. Here we discuss the theoretical analysis of various essential properties of the KRb molecules [2] that accompanied these experimental advances. This analysis is based on multi-channel bound-state calculations of both ground and excited electronic states. We have found that the theoretical hyperfine and Zeeman mixed X^1&+circ; and a^3&+circ; vibrational structure shows excellent agreement with the experimentally observed structure. In addition, multi-channel calculations of the rovibrational structure of the excited state potentials have allowed us to find the optimal transitions to the lowest v=0 vibrational levels. Finally, we examine the dynamic polarizability of vibrationally cold KRb molecules as a function of laser frequency. Based on this knowledge, laser frequencies can be selected to minimize decoherence from loss of molecules due to spontaneous or laser-induced transitions. [1] K.-K. Ni, S. Ospelkaus, M. H. G. de Miranda, A. Peer, B. Neyenhuis, J. J. Zirbel, S. Kotochigova, P. S. Julienne, D. S. Jin, and J. Ye, Science 322, 231 (2008). [2] S. Kotochigova, E. Tiesinga, and P. S. Julienne, submitted to New J. Phys. (2009).

The effects of repetitive vibration on sensorineural function: biomarkers of sensorineural injury in an animal model of metabolic syndrome

PubMed Central

Kiedrowski, Megan; Waugh, Stacey; Miller, Roger; Johnson, Claud; Krajnak, Kristine

2016-01-01

Exposure to hand-transmitted vibration in the work-place can result in the loss of sensation and pain in workers. These effects may be exacerbated by pre-existing conditions such as diabetes or the presence of primary Raynaud's phenomena. The goal of these studies was to use an established model of vibration-induced injury in Zucker rats. Lean Zucker rats have a normal metabolic profile, while obese Zucker rats display symptoms of metabolic disorder or Type II diabetes. This study examined the effects of vibration in obese and lean rats. Zucker rats were exposed to 4 h of vibration for 10 consecutive days at a frequency of 125 Hz and acceleration of 49 m/s2 for 10 consecutive days. Sensory function was checked using transcutaneous electrical stimulation on days 1, 5 and 9 of the exposure. Once the study was complete the ventral tail nerves, dorsal root ganglia and spinal cord were dissected, and levels of various transcripts involved in sensorineural dysfunction were measured. Sensorineural dysfunction was assessed using transcutaneous electrical stimulation. Obese Zucker rats displayed very few changes in sensorineural function. However they did display significant changes in transcript levels for factors involved in synapse formation, peripheral nerve remodeling, and inflammation. The changes in transcript levels suggested that obese Zucker rats had some level of sensory nerve injury prior to exposure, and that exposure to vibration activated pathways involved in injury and re-innervation. PMID:26433044

Evaluation of hand-arm and whole-body vibrations in construction and property management.

PubMed

Coggins, Marie A; Van Lente, Eric; McCallig, Margaret; Paddan, Gurmail; Moore, Ken

2010-11-01

To identify and measure the magnitude of hand-arm vibration (HAV) and whole-body vibration (WBV) sources (tools, vehicles etc.) in use within a previously unexamined sector: a construction and property management company. To evaluate the effect of factors such as age of tool, materials being worked on, number and location of tool handles, tool weight, and manufacturer brand on HAV magnitude and the effect of factors such as manufacturer machine brand, terrain, and work task on WBV magnitude. This study was carried out in a construction and property management company, employees (n = 469) working in the engineering services and maintenance departments who use vibrating equipment as part of their work were invited to participate. Two hundred and eighty-nine employees working as general operatives, excavator drivers, stone masons, carpenters, labourers, fitters, welders, and gardeners agreed to participate. A total of 20 types of hand tool (n = 264) and 11 types of vehicle (n = 158) in use within the company were selected for inclusion in the study. Five pieces of equipment had never previously been measured. Vibration measurements were carried out in accordance with ISO 5349-1 (Mechanical vibration-measurement and assessment of human exposure to hand transmitted vibration-Part 1: general guidance. 2001) (HAV) and ISO 2631-1 (Mechanical vibration and shock: evaluation of human exposure to WBV in the working environment. Part 1-general requirements. 1997) (WBV). Vibration measurements were made while workers were operating the equipment as part of their normal work activities. A wide range of vibration emission values were recorded for most tool types, e.g. orbital sanders (1.39-10.90 m s⁻²) and angle grinders (0.28-12.25 m s⁻²), and vehicle, e.g. forklifts (0.41-1.00 m s⁻²) and tractors (0.04-0.42 m s⁻²). Vibration magnitudes were largely consistent with those found in previous studies. The highest HAV magnitude was measured on a demolition hammer (13.3 m s⁻²) and the highest WBV magnitudes were measured on an excavator with a rock breaking attachment (5.81 m s⁻²). HAV magnitudes were found to be particularly strongly influenced by tool age, while WBV magnitudes varied with work activity and terrain. Within the construction and management company, few hand tools (3 of 20) exceeded the exposure action values (EAV) specified in the European Physical Agents (Vibration) Directive 2002/44/EC [On the minimum health and safety requirements regarding the exposure of works to the risks arising form physical agents (vibration)], when used for an 8-h period. HAV magnitudes were found to be very dependent on tool age, highlighting the importance of a tool maintenance programme incorporating tool work life prediction supported by regular vibration exposure measurements. Most of the vehicles (10 of 11) tested in this study exceeded the EAV specified for WBV, when operated for 8 h. WBV magnitudes were found to be dependent on the work task and thus, job rotation could be employed to control WBV exposures to acceptable levels.

A bio-inspired structural health monitoring system based on ambient vibration

NASA Astrophysics Data System (ADS)

Lin, Tzu-Kang; Kiremidjian, Anne; Lei, Chi-Yang

2010-11-01

A structural health monitoring (SHM) system based on naïve Bayesian (NB) damage classification and DNA-like expression data was developed in this research. Adapted from the deoxyribonucleic acid (DNA) array concept in molecular biology, the proposed structural health monitoring system is constructed utilizing a double-tier regression process to extract the expression array from the structural time history recorded during external excitations. The extracted array is symbolized as the various genes of the structure from the viewpoint of molecular biology and reflects the possible damage conditions prevalent in the structure. A scaled down, six-story steel building mounted on the shaking table of the National Center for Research on Earthquake Engineering (NCREE) was used as the benchmark. The structural response at different damage levels and locations under ambient vibration was collected to support the database for the proposed SHM system. To improve the precision of detection in practical applications, the system was enhanced by an optimization process using the likelihood selection method. The obtained array representing the DNA array of the health condition of the structure was first evaluated and ranked. A total of 12 groups of expression arrays were regenerated from a combination of four damage conditions. To keep the length of the array unchanged, the best 16 coefficients from every expression array were selected to form the optimized SHM system. Test results from the ambient vibrations showed that the detection accuracy of the structural damage could be greatly enhanced by the optimized expression array, when compared to the original system. Practical verification also demonstrated that a rapid and reliable result could be given by the final system within 1 min. The proposed system implements the idea of transplanting the DNA array concept from molecular biology into the field of SHM.

Gas Phase Molecular Spectroscopy: Electronic Spectroscopy of Combustion Intermediates, Chlorine Azide kinetics, and Rovibrational Energy Transfer in Acetylene

NASA Astrophysics Data System (ADS)

Freel, Keith A.

This dissertation is composed of three sections. The first deals with the electronic spectroscopy of combustion intermediates that are related to the formation of polycyclic aromatic hydrocarbons. Absorption spectra for phenyl, phenoxy, benzyl, and phenyl peroxy radicals were recorded using the technique of cavity ring-down spectroscopy. When possible, molecular constants, vibrational frequencies, and excited state lifetimes for these radicals were derived from these data. The results were supported by theoretical predictions. The second section presents a study of electron attachment to chlorine azide (ClN3) using a flowing-afterglow Langmuir-probe apparatus. Electron attachment rates were measured to be 3.5x10-8 and 4.5x10-8 cm3s-1 at 298 and 400 K respectively. The reactions of ClN3 with eighteen cations and seventeen anions were characterized. Rate constants were measured using a selected ion flow tube. The ionization energy (>9.6eV), proton affinity (713+/-41 kJ mol-1), and electron affinity (2.48+/-0.2 eV) for ClN 3 were determined from these data. The third section demonstrates the use of double resonance spectroscopy to observe state-selected rovibrational energy transfer from the first overtone asymmetric stretch of acetylene. The total population removal rate constants from various rotational levels of the (1,0,1,00,00) vibrational state were determined to be in the range of (9-17) x 10 -10 cm3s-1. Rotational energy transfer accounted for approximately 90% of the total removal rate from each state. Therefore, the upper limit of vibrational energy transfer from the (1,0,1,0 0,00) state was 10%.

Amplitude control of the track-induced self-excited vibration for a maglev system.

PubMed

Zhou, Danfeng; Li, Jie; Zhang, Kun

2014-09-01

The Electromagnet Suspension (EMS) maglev train uses controlled electromagnetic forces to achieve suspension, and self-excited vibration may occur due to the flexibility of the track. In this article, the harmonic balance method is applied to investigate the amplitude of the self-excited vibration, and it is found that the amplitude of the vibration depends on the voltage of the power supplier. Based on this observation, a vibration amplitude control method, which controls the amplitude of the vibration by adjusting the voltage of the power supplier, is proposed to attenuate the vibration. A PI controller is designed to control the amplitude of the vibration at a given level. The effectiveness of this method shows a good prospect for its application to commercial maglev systems. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

Some Aspects of the Investigation of Random Vibration Influence on Ride Comfort

NASA Astrophysics Data System (ADS)

DEMIĆ, M.; LUKIĆ, J.; MILIĆ, Ž.

2002-05-01

Contemporary vehicles must satisfy high ride comfort criteria. This paper attempts to develop criteria for ride comfort improvement. The highest loading levels have been found to be in the vertical direction and the lowest in lateral direction in passenger cars and trucks. These results have formed the basis for further laboratory and field investigations. An investigation of the human body behaviour under random vibrations is reported in this paper. The research included two phases; biodynamic research and ride comfort investigation. A group of 30 subjects was tested. The influence of broadband random vibrations on the human body was examined through the seat-to-head transmissibility function (STHT). Initially, vertical and fore and aft vibrations were considered. Multi-directional vibration was also investigated. In the biodynamic research, subjects were exposed to 0·55, 1·75 and 2·25 m/s2 r.m.s. vibration levels in the 0·5- 40 Hz frequency domain. The influence of sitting position on human body behaviour under two axial vibrations was also examined. Data analysis showed that the human body behaviour under two-directional random vibrations could not be approximated by superposition of one-directional random vibrations. Non-linearity of the seated human body in the vertical and fore and aft directions was observed. Seat-backrest angle also influenced STHT. In the second phase of experimental research, a new method for the assessment of the influence of narrowband random vibration on the human body was formulated and tested. It included determination of equivalent comfort curves in the vertical and fore and aft directions under one- and two-directional narrowband random vibrations. Equivalent comfort curves for durations of 2·5, 4 and 8 h were determined.

Vibrational population of the A super 3 sigma sub u/+/ and B super 3 pi sub g states of N2 in normal auroras.

NASA Technical Reports Server (NTRS)

Cartwright, D. C.; Trajmar, S.; Williams, W.

1971-01-01

Use of new electron impact excitation cross sections for the six lowest triplet states (A, B, W, C, E, D) of N2, and solution of the coupled equations of statistical equilibrium to obtain the vibrational population of each electronic state. The results show that cascade from high levels of the A super 3 sigma sub u(+) state and from the W super 3 delta sub u state is significant in populating the lower vibrational levels of the B state and hence the character of its ?apparent' excitation cross sections. For the B state excited under auroral conditions, the fraction of the total population due to cascade processes exceeds 25% for all levels lower than 7 and is greater than 80% for B(v' = 0). For the A state under similar conditions, cascade from the B state contributes 50% or more of the total vibrational population for levels lower than 7, and 80% or more for levels below 4. For levels of the A state greater than 7, the A yields B transitions depopulate the levels rapidly and indicate that the Vegard-Kaplan emissions from these higher levels will be weak or totally absent in normal auroras.

Vibration-rotation-tunneling dynamics in small water clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pugliano, N.

The goal of this work is to characterize the intermolecular vibrations of small water clusters. Using tunable far infrared laser absorption spectroscopy, large amplitude vibration-rotation-tunneling (VRT) dynamics in vibrationally excited states of the water dimer and the water trimer are investigated. This study begins with the measurement of 12 VRT subbands, consisting of approximately 230 transitions, which are assigned to an 82.6 cm[sup [minus]1] intermolecular vibration of the water dimer-d[sub 4]. Each of the VRT subbands originate from K[sub a][double prime]=0 and terminate in either K[sub a][prime]=0 or 1. These data provide a complete characterization of the tunneling dynamics inmore » the vibrationally excited state as well as definitive symmetry labels for all VRT energy levels. Furthermore, an accurate value for the A[prime] rotational constant is found to agree well with its corresponding ground state value. All other excited state rotational constants are fitted, and discussed in terms of the corresponding ground state constants. In this vibration, the quantum tunneling motions are determined to exhibit large dependencies with both the K[sub a][prime] quantum number and the vibrational coordinate, as is evidenced by the measured tunneling splittings. The generalized internal-axis-method treatment which has been developed to model the tunneling dynamics, is considered for the qualitative description of each tunneling pathway, however, the variation of tunneling splittings with vibrational excitation indicate that the high barrier approximation does not appear to be applicable for this vibrational coordinate. The data are consistent with a motion possessing a[prime] symmetry, and the vibration is assigned as the [nu][sub 12] acceptor bending coordinate. This assignment is in agreement with the vibrational symmetry, the resultsof high level ab initio calculations, and preliminary data assigned to the analogous vibration in the D[sub 2]O-DOH isotopomer.« less

Preparation of a single highly vibrationally excited quantum state using Stark induced adiabatic Raman passage

NASA Astrophysics Data System (ADS)

Perreault, William; Mukherjee, Nandini; Zare, Richard

2017-04-01

Stark induced adiabatic Raman passage (SARP) allows us to prepare an appreciable concentration of isolated molecules in a specific highly excited vibrational level. As a demonstration, we transfer nearly 100% of the HD (v =0, J =0) in a supersonically expanded molecular beam of HD molecules to HD (v =4, J =0). This is achieved with a sequence of partially overlapping nanosecond pump (355 nm) and Stokes (680 nm) single-mode laser pulses of unequal intensities. The experimental spectral broadening with pump to Stokes delay and saturation against Stokes power suggest that complete population transfer has been achieved from the initial HD (v =0, J =0) to the target (v =4, J =0). By comparing our experimental data with our theoretical calculations we are able to draw two important conclusions: (1) using SARP a large population (>1010 molecules per laser pulse) is prepared in the (v =4, J =0) level of HD, and (2) the polarizability α00 , 40 (0.6 x 10-41Cm2V-1) for the (v =0, J =0) to (v =4, J =0) Raman overtone transition is only about five times smaller than α00 , 10 for the (v =0, J =0) to (v =1, J =0) fundamental Raman transition. This capability of preparing selected, highly excited vibrational quantum states of molecules opens new opportunities for fundamental scattering experiments. This work has been supported by the U.S. Army Research Office under ARO Grant No. W911NF-16-1-1061, and MURI Grant No. W911NF-12-1-0476.

Vibration-reducing gloves: transmissibility at the palm of the hand in three orthogonal directions.

PubMed

McDowell, Thomas W; Dong, Ren G; Welcome, Daniel E; Xu, Xueyan S; Warren, Christopher

2013-01-01

Vibration-reducing (VR) gloves are commonly used as a means to help control exposures to hand-transmitted vibrations generated by powered hand tools. The objective of this study was to characterise the vibration transmissibility spectra and frequency-weighted vibration transmissibility of VR gloves at the palm of the hand in three orthogonal directions. Seven adult males participated in the evaluation of seven glove models using a three-dimensional hand-arm vibration test system. Three levels of hand coupling force were applied in the experiment. This study found that, in general, VR gloves are most effective at reducing vibrations transmitted to the palm along the forearm direction. Gloves that are found to be superior at reducing vibrations in the forearm direction may not be more effective in the other directions when compared with other VR gloves. This casts doubts on the validity of the standardised glove screening test. Practitioner Summary: This study used human subjects to measure three-dimensional vibration transmissibility of vibration-reducing gloves at the palm and identified their vibration attenuation characteristics. This study found the gloves to be most effective at reducing vibrations along the forearm direction. These gloves did not effectively attenuate vibration along the handle axial direction.

Design sensitivity analysis of rotorcraft airframe structures for vibration reduction

NASA Technical Reports Server (NTRS)

Murthy, T. Sreekanta

1987-01-01

Optimization of rotorcraft structures for vibration reduction was studied. The objective of this study is to develop practical computational procedures for structural optimization of airframes subject to steady-state vibration response constraints. One of the key elements of any such computational procedure is design sensitivity analysis. A method for design sensitivity analysis of airframes under vibration response constraints is presented. The mathematical formulation of the method and its implementation as a new solution sequence in MSC/NASTRAN are described. The results of the application of the method to a simple finite element stick model of the AH-1G helicopter airframe are presented and discussed. Selection of design variables that are most likely to bring about changes in the response at specified locations in the airframe is based on consideration of forced response strain energy. Sensitivity coefficients are determined for the selected design variable set. Constraints on the natural frequencies are also included in addition to the constraints on the steady-state response. Sensitivity coefficients for these constraints are determined. Results of the analysis and insights gained in applying the method to the airframe model are discussed. The general nature of future work to be conducted is described.

State selected ion--molecule reactions by a TESICO technique. V. N/sub 2//sup +/(v)+Ar. -->. N/sub 2/+Ar/sup +/

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kato, T.; Tanaka, K.; Koyano, I.

1982-07-15

Charge transfer reactions N/sub 2//sup +/(v)+Ar..-->..Ar/sup +/+N/sub 2/ (1) have been studied by selecting the vibrational states of N/sub 2//sup +/ using the threshold electron--secondary ion coincidence (TESICO) technique. Relative cross sections sigma(v) for the individual vibrational states v = 0--3 have been determined at three collision energies, 0.3, 1.5, and 11.8 eV. Results show that Reaction (1), which is endoergic for v = 0, is considerably enhanced by the vibrational excitation of N/sub 2//sup +/ at all collision energies. While excitation of one vibrational quantum enhances the cross section substantially, excitation of additional quanta further increases the cross sectionmore » up to v = 3. The ratios sigma(2)/sigma(1) and sigma(3)/sigma(2) are, however, much smaller than sigma(1)/sigma(0) and are significantly larger at the highest collision energy than at the other two collision energies. These results are discussed in conjunction with the calculated results based on the simple two-state theory of Rapp and Francis and the Franck--Condon factors.« less

Frequency characteristics of human muscle and cortical responses evoked by noisy Achilles tendon vibration.

PubMed

Mildren, Robyn L; Peters, Ryan M; Hill, Aimee J; Blouin, Jean-Sébastien; Carpenter, Mark G; Inglis, J Timothy

2017-05-01

Noisy stimuli, along with linear systems analysis, have proven to be effective for mapping functional neural connections. We explored the use of noisy (10-115 Hz) Achilles tendon vibration to examine somatosensory reflexes in the triceps surae muscles in standing healthy young adults ( n = 8). We also examined the association between noisy vibration and electrical activity recorded over the sensorimotor cortex using electroencephalography. We applied 2 min of vibration and recorded ongoing muscle activity of the soleus and gastrocnemii using surface electromyography (EMG). Vibration amplitude was varied to characterize reflex scaling and to examine how different stimulus levels affected postural sway. Muscle activity from the soleus and gastrocnemii was significantly correlated with the tendon vibration across a broad frequency range (~10-80 Hz), with a peak located at ~40 Hz. Vibration-EMG coherence positively scaled with stimulus amplitude in all three muscles, with soleus displaying the strongest coupling and steepest scaling. EMG responses lagged the vibration by ~38 ms, a delay that paralleled observed response latencies to tendon taps. Vibration-evoked cortical oscillations were observed at frequencies ~40-70 Hz (peak ~54 Hz) in most subjects, a finding in line with previous reports of sensory-evoked γ-band oscillations. Further examination of the method revealed 1 ) accurate reflex estimates could be obtained with <60 s of low-level (root mean square = 10 m/s 2 ) vibration; 2 ) responses did not habituate over 2 min of exposure; and importantly, 3 ) noisy vibration had a minimal influence on standing balance. Our findings suggest noisy tendon vibration is an effective novel approach to characterize somatosensory reflexes during standing. NEW & NOTEWORTHY We applied noisy (10-115 Hz) vibration to the Achilles tendon to examine the frequency characteristics of lower limb somatosensory reflexes during standing. Ongoing muscle activity was coherent with the noisy vibration (peak coherence ~40 Hz), and coherence positively scaled with increases in stimulus amplitude. Our findings suggest that noisy tendon vibration, along with linear systems analysis, is an effective novel approach to study somatosensory reflex actions in active muscles. Copyright © 2017 the American Physiological Society.

Low-magnitude mechanical vibration regulates expression of osteogenic proteins in ovariectomized rats.

PubMed

Li, Ming; Wu, Wei; Tan, Lei; Mu, Degong; Zhu, Dong; Wang, Jian; Zhao, Bin

2015-09-25

The present study aimed to investigate the impact of low-magnitude and high-frequency mechanical vibration with various lengths of resting period incorporated between loading cycles on the expression of osteogenesis-related proteins in a rat model of osteoporosis. The rats in the mechanical loading groups received low-magnitude and high-frequency vibration (35 Hz and acceleration of 0.25 g, 15 min/day) for 8 weeks. Bilateral humeral heads and femoral heads were then isolated, and protein levels of bone morphogenetic protein 2 (BMP-2), extracellular signal-regulated kinase 1/2 (ERK1/2), phosphorylated ERK1/2 (p-ERK1/2), runt-related transcription factor 2 (Runx2) and osteocalcin (OCN) were determined by Western blotting. Increased levels of BMP-2, Runx2 and OCN were observed in rats receiving mechanical vibration. Total ERK1/2 protein remained unchanged, whereas the level of activated ERK1/2 (p-ERK1/2) increased after mechanical vibration. Vibration with incorporated resting period, regardless of length, was more effective in inducing expression of these osteogenic proteins, and the vibration with 7-day resting period had the most profound impact. Signals from low-magnitude and high-frequency mechanical vibration upregulated the expression of BMP-2 and Runx2, activated the ERK1/2 signaling pathway, and consequently led to increased expression of OCN. The anabolic effect of mechanical stimulation was enhanced with incorporation of resting period between loadings, and the one with 7-day resting period exhibited the strongest effect among all. Our results could provide a reference for development of mechanical stimulation as a non-pharmacological intervention for osteoporosis. Copyright © 2015 Elsevier Inc. All rights reserved.

Female choice in the red mason bee, Osmia rufa (L.) (Megachilidae).

PubMed

Conrad, Taina; Paxton, Robert J; Barth, Friedrich G; Francke, Wittko; Ayasse, Manfred

2010-12-01

Females are often thought to use several cues and more than one modality in selection of a mate, possibly because they offer complementary information on a mate's suitability. In the red mason bee, Osmia rufa, we investigated the criteria a female uses to choose a mating partner. We hypothesized that the female uses male thorax vibrations and size as signs of male viability and male odor for kin discrimination and assessment of genetic relatedness. We therefore compared males that had been accepted by a female for copulation with those rejected, in terms of their size, their immediate precopulatory vibrations (using laser vibrometry), the genetic relatedness of unmated and mated pairs (using microsatellite markers) and emitted volatiles (using chemical analyses). Females showed a preference for intermediate-sized males that were slightly larger than the modal male size. Furthermore, male precopulatory vibration burst duration was significantly longer in males accepted for copulation compared with rejected males. Vibrations may indicate vigor and assure that males selected by females are metabolically active and healthy. Females preferentially copulated with males that were genetically more closely related, possibly to avoid outbreeding depression. Volatiles of the cuticular surface differed significantly between accepted and rejected males in the relative amounts of certain hydrocarbons, although the relationship between male odor and female preference was complex. Females may therefore also use differences in odor bouquet to select among males. Our investigations show that O. rufa females appear to use multiple cues in selecting a male. Future investigations are needed to demonstrate whether odor plays a role in kin recognition and how the multiple cues are integrated in mate choice by females.

Investigation on flow and mixing characteristics of supersonic mixing layer induced by forced vibration of cantilever

NASA Astrophysics Data System (ADS)

Zhang, Dongdong; Tan, Jianguo; Lv, Liang

2015-12-01

The mixing process has been an important issue for the design of supersonic combustion ramjet engine, and the mixing efficiency plays a crucial role in the improvement of the combustion efficiency. In the present study, nanoparticle-based planar laser scattering (NPLS), particle image velocimetry (PIV) and large eddy simulation (LES) are employed to investigate the flow and mixing characteristics of supersonic mixing layer under different forced vibration conditions. The indexes of fractal dimension, mixing layer thickness, momentum thickness and scalar mixing level are applied to describe the mixing process. Results show that different from the development and evolution of supersonic mixing layer without vibration, the flow under forced vibration is more likely to present the characteristics of three-dimensionality. The laminar flow region of mixing layer under forced vibration is greatly shortened and the scales of rolled up Kelvin-Helmholtz vortices become larger, which promote the mixing process remarkably. The fractal dimension distribution reveals that comparing with the flow without vibration, the turbulent fluctuation of supersonic mixing layer under forced vibration is more intense. Besides, the distribution of mixing layer thickness, momentum thickness and scalar mixing level are strongly influenced by forced vibration. Especially, when the forcing frequency is 4000 Hz, the mixing layer thickness and momentum thickness are 0.0391 m and 0.0222 m at the far field of 0.16 m, 83% and 131% higher than that without vibration at the same position, respectively.

Changes in tibialis anterior corticospinal properties after acute prolonged muscle vibration.

PubMed

Farabet, Adrien; Souron, Robin; Millet, Guillaume Y; Lapole, Thomas

2016-06-01

Prolonged local vibration is known to impair muscle performance. While involved mechanisms were previously evidenced at the spinal level, changes at the cortical level were also hypothesized. The aims of the present study were to investigate the effects of 30 min of 100-Hz tibialis anterior muscle vibration on force production capacities and to further identify the respective changes in spinal loop properties, descending voluntary drive and corticospinal properties. Thirteen subjects were tested before and after a vibration condition, and before and after a resting control condition. Maximal voluntary contraction (MVC) in dorsiflexion was measured. Transcranial magnetic stimulation was superimposed during MVCs to assess cortical voluntary activation (VATMS), motor-evoked potential amplitude (MEP) and cortical silent period length (CSP). MEP and CSP were also measured during 50 and 75 % MVC contractions. Spinal excitability was investigated by mean of H-reflex. There were no vibration effects on MVC (p = 0.805), maximal EMG activity (p = 0.653), VATMS (p = 1), and CSP (p = 0.877). Vibration tended to decrease MEP amplitude (p = 0.117). H-reflex amplitude was depressed following vibration (p = 0.008). Dorsiflexion maximal force production capacities were unaffected by 30 min of tibialis anterior muscle vibration, despite spinal loop and corticospinal excitabilities being reduced. These findings suggest that acute prolonged vibration has the potential to modulate corticospinal excitability of lower limb muscles without a concomitant functional consequence.

Vibration transmission through sheet webs of hobo spiders (Eratigena agrestis) and tangle webs of western black widow spiders (Latrodectus hesperus).

PubMed

Vibert, Samantha; Scott, Catherine; Gries, Gerhard

2016-11-01

Web-building spiders construct their own vibratory signaling environments. Web architecture should affect signal design, and vice versa, such that vibratory signals are transmitted with a minimum of attenuation and degradation. However, the web is the medium through which a spider senses both vibratory signals from courting males and cues produced by captured prey. Moreover, webs function not only in vibration transmission, but also in defense from predators and the elements. These multiple functions may impose conflicting selection pressures on web design. We investigated vibration transmission efficiency and accuracy through two web types with contrasting architectures: sheet webs of Eratigena agrestis (Agelenidae) and tangle webs of Latrodectus hesperus (Theridiidae). We measured vibration transmission efficiencies by playing frequency sweeps through webs with a piezoelectric vibrator and a loudspeaker, recording the resulting web vibrations at several locations on each web using a laser Doppler vibrometer. Transmission efficiencies through both web types were highly variable, with within-web variation greater than among-web variation. There was little difference in transmission efficiencies of longitudinal and transverse vibrations. The inconsistent transmission of specific frequencies through webs suggests that parameters other than frequency are most important in allowing these spiders to distinguish between vibrations of prey and courting males.

High-Level, First-Principles, Full-Dimensional Quantum Calculation of the Ro-vibrational Spectrum of the Simplest Criegee Intermediate (CH2OO).

PubMed

Li, Jun; Carter, Stuart; Bowman, Joel M; Dawes, Richard; Xie, Daiqian; Guo, Hua

2014-07-03

The ro-vibrational spectrum of the simplest Criegee intermediate (CH2OO) has been determined quantum mechanically based on nine-dimensional potential energy and dipole surfaces for its ground electronic state. The potential energy surface is fitted to more than 50 000 high-level ab initio points with a root-mean-square error of 25 cm(-1), using a recently proposed permutation invariant polynomial neural network method. The calculated rotational constants, vibrational frequencies, and spectral intensities of CH2OO are in excellent agreement with experiment. The potential energy surface provides a valuable platform for studying highly excited vibrational and unimolecular reaction dynamics of this important molecule.

Architecture for distributed actuation and sensing using smart piezoelectric elements

NASA Astrophysics Data System (ADS)

Etienne-Cummings, Ralph; Pourboghrat, Farzad; Maruboyina, Hari K.; Abrate, Serge; Dhali, Shirshak K.

1998-07-01

We discuss vibration control of a cantilevered plate with multiple sensors and actuators. An architecture is chosen to minimize the number of control and sensing wires required. A custom VLSI chip, integrated with the sensor/actuator elements, controls the local behavior of the plate. All the actuators are addressed in parallel; local decode logic selects which actuator is stimulated. Downloaded binary data controls the applied voltage and modulation frequency for each actuator, and High Voltage MOSFETs are used to activate them. The sensors, which are independent adjacent piezoelectric ceramic elements, can be accessed in a random or sequential manner. An A/D card and GPIB interconnected test equipment allow a PC to read the sensors' outputs and dictate the actuation procedure. A visual programming environment is used to integrate the sensors, controller and actuators. Based on the constitutive relations for the piezoelectric material, simple models for the sensors and actuators are derived. A two level hierarchical robust controller is derived for motion control and for damping of vibrations.

78 FR 2198 - Airworthiness Directives; Turbomeca S.A. Turboshaft Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-10

... high GG speed (NG) rating vibration check. (f) Definition Level 3 maintenance on the GG rotating... performing a high gas generator speed (NG) rating vibration check. This AD was prompted by several reports of... bearing failures have occurred following ``Level 3'' maintenance actions on the GG rotating assembly. Some...

A comparison of whole body vibration and moist heat on lower extremity skin temperature and skin blood flow in healthy older individuals.

PubMed

Lohman, Everett B; Sackiriyas, Kanikkai Steni Balan; Bains, Gurinder S; Calandra, Giovanni; Lobo, Crystal; Nakhro, Daniel; Malthankar, Gauri; Paul, Sherwine

2012-07-01

Tissue healing is an intricate process that is regulated by circulation. Heat modalities have been shown to improve skin circulation. Recent research supports that passive vibration increases circulation without risk of burns. Study purpose is to compare and determine effects of short duration vibration, moist heat, and a combination of the two on skin blood flow (SBF) and skin temperature (ST) in elderly, non-diabetic individuals following short-term exposure. Ten subjects, 3 female and 7 male (55-73 years of age), received two interventions over three days: 1--Active vibration, 2--passive vibration, 3--moist heat, 4--moist heat combined with passive vibration (MHPV), 5--a commercial massaging heating pad, and 6--no intervention. SBF and ST were measured using a MOOR Laser Doppler before and after the intervention and the third measurement were taken 10 minutes following. Mean SBF following a ten-minute intervention were significantly different in the combination of moist heat and passive vibration from the control, active vibration, and the commercial massaging heating pad. Compared to baseline measurements, this resulted in mean SBF elevation to 450% (at conclusion of 10 minutes of intervention) and 379% (10 minutes post). MHPV (p=0.02) showed significant changes in ST from the commercial massaging heating pad, passive vibration, and active vibration interventions. SBF in the lower legs showed greatest increase with MHPV. Interventions should be selected that are low risk while increasing lower extremity skin blood flow.

Structural parameter study on polymer-based ultrasonic motor

NASA Astrophysics Data System (ADS)

Wu, Jiang; Mizuno, Yosuke; Nakamura, Kentaro

2017-11-01

Our previous study has shown that traveling-wave rotary ultrasonic motors using polymer-based vibrators can work in the same way as conventional motors with metal-based vibrators. It is feasible to enhance the performance, particularly output torques, of polymer-based motors by adjusting several key dimensions of their vibrators. In this study, poly phenylene sulfide, a functional polymer exhibiting low attenuation at ultrasonic frequency, is selected as the vibrating body, which is activated with a piezoelectric ceramic element bonded on its back surface. The optimal thicknesses of the polymer-based motors are higher than those of metal-based motors. When the same voltages were applied, the maximum torques and output powers available with the polymer-based motors were lower than the values of the metal-based motors with the same structures. The reasons for the lower torque were explained on the basis of vibration modes. First, the force factors of the polymer-based vibrators are lower than those of metal-based vibrators owing to the great difference in the mechanical constants between polymers and piezoelectric ceramics. Subsequently, though the force factors of polymer-based vibrators can be slightly enhanced by increasing their thicknesses, the unavoidable radial vibrations become higher and cause undesirable friction loss, which reduces the output torques. Though the polymer-based motors have rotation speeds comparable to those of metal-based motors, their output power are lower due to the low electromechanical coupling factors of the polymer-based vibrators.

Acta Aeronautica et Astronautica Sinica (Selected Articles),

DTIC Science & Technology

1986-05-09

Let us assume the third vibration mode. Then, the matrix form of the coupled linear equations is obtained as follows: 30 L. -i .- *’ v j h 1. - Y I - u5...F When higher vibration modes are considered, the same m~ethod can be used. From eqn. (31,we have the transfer functions: A c,37 + Cse+ C,s+ C, $+ C’s... vibration modes of the gyro at point 1 with respect to x. Then, transfer function, .WO (s) is s)=W, 1( I )W, 1 ( s ) 2( 1 )W,( S T- ( I s ) l, 3 7+1,s+1 1 ls

Preliminary vibration, acoustic, and shock design and test criteria for components on the Lightweight External Tank (LWT)

NASA Technical Reports Server (NTRS)

1981-01-01

The Space Shuttle LWT is divided into zones and subzones. Zones are designated primarily to assist in determining the applicable specifications. A subzone (general Specification) is available for use when the location of the component is known but component design and weight are not well defined. When the location, weight, and mounting configuration of the component are known, specifications for appropriate subzone weight ranges are available. Along with the specifications are vibration, acoustic, shock, transportation, handling, and acceptance test requirements and procedures. A method of selecting applicable vibration, acoustic, and shock specifications is presented.

Vibrational structure in the photo-electron spectrum of O2+2Sigma(g)-(sigmag2s)

NASA Technical Reports Server (NTRS)

Gardner, J. L.; Samson, J. A. R.

1974-01-01

Discrete vibrational structure has been observed in the photo-electron spectrum of oxygen at an ionization potential of 40.33 eV. Two levels, attributed to the 02(+) 2 sigma g- final state, have been detected with a vibrational spacing of 0.071 eV.

Production, Delivery and Application of Vibration Energy in Healthcare

NASA Astrophysics Data System (ADS)

Abundo, Paolo; Trombetta, Chiara; Foti, Calogero; Rosato, Nicola

2011-02-01

In Rehabilitation Medicine therapeutic application of vibration energy in specific clinical treatments and in sport rehabilitation is being affirmed more and more.Vibration exposure can have positive or negative effects on the human body depending on the features and time of the characterizing wave. The human body is constantly subjected to different kinds of vibrations, inducing bones and muscles to actively modify their structure and metabolism in order to fulfill the required functions. Like every other machine, the body supports only certain vibration energy levels over which long term impairments can be recognized. As shown in literature anyway, short periods of vibration exposure and specific frequency values can determine positive adjustments.

Towards an automated and efficient calculation of resonating vibrational states based on state-averaged multiconfigurational approaches

NASA Astrophysics Data System (ADS)

Meier, Patrick; Oschetzki, Dominik; Pfeiffer, Florian; Rauhut, Guntram

2015-12-01

Resonating vibrational states cannot consistently be described by single-reference vibrational self-consistent field methods but request the use of multiconfigurational approaches. Strategies are presented to accelerate vibrational multiconfiguration self-consistent field theory and subsequent multireference configuration interaction calculations in order to allow for routine calculations at this enhanced level of theory. State-averaged vibrational complete active space self-consistent field calculations using mode-specific and state-tailored active spaces were found to be very fast and superior to state-specific calculations or calculations with a uniform active space. Benchmark calculations are presented for trans-diazene and bromoform, which show strong resonances in their vibrational spectra.

Towards an automated and efficient calculation of resonating vibrational states based on state-averaged multiconfigurational approaches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meier, Patrick; Oschetzki, Dominik; Pfeiffer, Florian

Resonating vibrational states cannot consistently be described by single-reference vibrational self-consistent field methods but request the use of multiconfigurational approaches. Strategies are presented to accelerate vibrational multiconfiguration self-consistent field theory and subsequent multireference configuration interaction calculations in order to allow for routine calculations at this enhanced level of theory. State-averaged vibrational complete active space self-consistent field calculations using mode-specific and state-tailored active spaces were found to be very fast and superior to state-specific calculations or calculations with a uniform active space. Benchmark calculations are presented for trans-diazene and bromoform, which show strong resonances in their vibrational spectra.

Fundamental Vibration of Molecular Hydrogen

NASA Astrophysics Data System (ADS)

Dickenson, G. D.; Niu, M. L.; Salumbides, E. J.; Komasa, J.; Eikema, K. S. E.; Pachucki, K.; Ubachs, W.

2013-05-01

The fundamental ground tone vibration of H2, HD, and D2 is determined to an accuracy of 2×10-4cm-1 from Doppler-free laser spectroscopy in the collisionless environment of a molecular beam. This rotationless vibrational splitting is derived from the combination difference between electronic excitation from the X1Σg+, v=0, and v=1 levels to a common EF1Σg+, v=0 level. Agreement within 1σ between the experimental result and a full ab initio calculation provides a stringent test of quantum electrodynamics in a chemically bound system.

Summary of semi-initiative and initiative control automobile engine vibration

NASA Astrophysics Data System (ADS)

Qu, Wei; Qu, Zhou

2009-07-01

Engine vibration accounts for around 55% of automobile vibration, separating the engine vibration from transmitting to automobile to the utmost extent is significant for improving NVH performance. Semi-initiative and initiative control of engine vibration is one of the hot spots of technical research in domestic and foreign automobile industry, especially luxury automobiles which adopt this technology to improve amenity and competitiveness. This article refers to a large amount of domestic and foreign related materials, fully introduces the research status of semi-initiative and initiative control suspension of engine vibration suspension and many kinds of structural style, and provides control policy and method of semi-initiative and initiative control suspension system. Compare and analyze the structural style of semi-initiative and initiative control and merits and demerits of current structures of semi-initiative and initiative control of mechanic electrorheological, magnetorheological, electromagnetic actuator, piezoelectric ceramics, electrostriction material, pneumatic actuator etc. Models of power assembly mounting system was classified.Calculation example indicated that reasonable selection of engine mounting system parameters is useful to reduce engine vibration transmission and to increase ride comfort. Finally we brought forward semi-initiative and initiative suspension which might be applied for automobiles, and which has a promising future.

A numerical analysis of the influence of tram characteristics and rail profile on railway traffic ground-borne noise and vibration in the Brussels Region.

PubMed

Kouroussis, G; Pauwels, N; Brux, P; Conti, C; Verlinden, O

2014-06-01

Nowadays, damage potentially caused by passing train in dense cities is of increasing concern and restricts improvement to the interconnection of various public transport offers. Although experimental studies are common to quantify the effects of noise and vibration on buildings and on people, their reach is limited since the causes of vibrations can rarely be deduced from data records. This paper presents the numerical calculations that allow evaluating the main contributions of railway-induced ground vibrations in the vicinity of buildings. The reference case is the Brussels Region and, more particularly, the T2000 tram circulating in Brussels city. Based on a pertinent selection of the vibration assessment indicators and a numerical prediction approach, various results are presented and show that the free-field analysis is often improperly used in this kind of analysis as the interaction of soil and structure is required. Calculated high ground vibrations stem from singular rail surface defects. The use of resilient wheels is recommended in order to reduce the ground-borne noise and vibration to permissible values. Copyright © 2013 Elsevier B.V. All rights reserved.

Corneal Vibrations during Intraocular Pressure Measurement with an Air-Puff Method

PubMed Central

Wilczyński, Sławomir

2018-01-01

Introduction The paper presents a commentary on the method of analysis of corneal vibrations occurring during eye pressure measurements with air-puff tonometers, for example, Corvis. The presented definition and measurement method allow for the analysis of image sequences of eye responses—cornea deformation. In particular, the outer corneal contour and sclera fragments are analysed, and 3D reconstruction is performed. Methods On this basis, well-known parameters such as eyeball reaction or corneal response are determined. The next steps of analysis allow for automatic and reproducible separation of four different corneal vibrations. These vibrations are associated with (1) the location of the maximum of cornea deformation; (2) the cutoff area measured in relation to the cornea in a steady state; (3) the maximum of peaks occurring between applanations; and (4) the other characteristic points of the corneal contour. Results The results obtained enable (1) automatic determination of the amplitude of vibrations; (2) determination of the frequency of vibrations; and (3) determination of the correlation between the selected types of vibrations. Conclusions These are diagnostic features that can be directly applied clinically for new and archived data. PMID:29610655

Integrated cable vibration control system using wireless sensors

NASA Astrophysics Data System (ADS)

Jeong, Seunghoo; Cho, Soojin; Sim, Sung-Han

2017-04-01

As the number of long-span bridges is increasing worldwide, maintaining their structural integrity and safety become an important issue. Because the stay cable is a critical member in most long-span bridges and vulnerable to wind-induced vibrations, vibration mitigation has been of interest both in academia and practice. While active and semi-active control schemes are known to be quite effective in vibration reduction compared to the passive control, requirements for equipment including data acquisition, control devices, and power supply prevent a widespread adoption in real-world applications. This study develops an integrated system for vibration control of stay-cables using wireless sensors implementing a semi-active control. Arduino, a low-cost single board system, is employed with a MEMS digital accelerometer and a Zigbee wireless communication module to build the wireless sensor. The magneto-rheological (MR) damper is selected as a damping device, controlled by an optimal control algorithm implemented on the Arduino sensing system. The developed integrated system is tested in a laboratory environment using a cable to demonstrate the effectiveness of the proposed system on vibration reduction. The proposed system is shown to reduce the vibration of stay-cables with low operating power effectively.

Characteristics of 1.9-μm laser emission from hydrogen-filled hollow-core fiber by vibrational stimulated Raman scattering

NASA Astrophysics Data System (ADS)

Gu, Bo; Chen, Yubin; Wang, Zefeng

2016-12-01

We report here the characteristics of 1.9-μm laser emission from a gas-filled hollow-core fiber by stimulated Raman scattering (SRS). A 6.5-m hydrogen-filled ice-cream negative curvature hollow-core fiber is pumped with a high peak-power, narrow linewidth, linearly polarized subnanosecond pulsed 1064-nm microchip laser, generating a pulsed vibrational Stokes wave at 1908.5 nm. The maximum quantum efficiency of about 48% is obtained, which is mainly limited by the mode mismatch between the pump laser beam and the Stokes wave in the hollow-core fiber. The linewidths of the pump laser and the first-order vibrational Stokes wave are measured to be about 1 and 2 GHz, respectively, by a scanning Fabry-Perot interferometer. The pressure selection phenomenon of the vibrational anti-Stokes waves is also investigated. The pulse duration of the vibrational Stokes wave is recorded to be narrower than that of the pump laser. The polarization properties of the hollow-core fiber and the polarization dependence of the vibrational and the rotational SRS are also studied. The beam profile of the vibrational Stokes wave shows good quality.

Estimation of vibration frequency of loudspeaker diaphragm by parallel phase-shifting digital holography

NASA Astrophysics Data System (ADS)

Kakue, T.; Endo, Y.; Shimobaba, T.; Ito, T.

2014-11-01

We report frequency estimation of loudspeaker diaphragm vibrating at high speed by parallel phase-shifting digital holography which is a technique of single-shot phase-shifting interferometry. This technique records multiple phaseshifted holograms required for phase-shifting interferometry by using space-division multiplexing. We constructed a parallel phase-shifting digital holography system consisting of a high-speed polarization-imaging camera. This camera has a micro-polarizer array which selects four linear polarization axes for 2 × 2 pixels. We set a loudspeaker as an object, and recorded vibration of diaphragm of the loudspeaker by the constructed system. By the constructed system, we demonstrated observation of vibration displacement of loudspeaker diaphragm. In this paper, we aim to estimate vibration frequency of the loudspeaker diaphragm by applying the experimental results to frequency analysis. Holograms consisting of 128 × 128 pixels were recorded at a frame rate of 262,500 frames per second by the camera. A sinusoidal wave was input to the loudspeaker via a phone connector. We observed displacement of the loudspeaker diaphragm vibrating by the system. We also succeeded in estimating vibration frequency of the loudspeaker diaphragm by applying frequency analysis to the experimental results.

The Role of Posterior Screw Fixation in Single-Level Transforaminal Lumbar Interbody Fusion During Whole Body Vibration: A Finite Element Study.

PubMed

Fan, Wei; Guo, Li-Xin

2018-06-01

Few studies have evaluated the need for supplementary instrumentation after lumbar interbody fusion under the condition of whole body vibration (WBV) that is typically present in vehicles. This study aimed to determine the effect of posterior pedicle screw fixation on dynamic response of the whole lumbar spine to vertical WBV after transforaminal lumbar interbody fusion (TLIF). A previously validated nonlinear, osteoligamentous finite element (FE) model of the intact L1-sacrum human lumbar spine was modified to simulate single-level (L4-L5) TLIF without and with bilateral pedicle screw fixation (BPSF). Transit dynamic analysis was performed on the 2 developed models under a sinusoidal vertical vibration load of ±40 N and a compressive follower preload of 400 N. The resulting dynamic response results for the 2 models in terms of stresses and deformations were recorded and compared. When compared with no fixation, BPSF decreased dynamic responses of the spinal levels to the vertical vibration after TLIF. At the fused level (L4-L5), vibration amplitudes of the von-Mises stresses in L4 inferior endplate and L5 superior endplate decreased after BPSF by 48.0% and 46.4%, respectively. At other disc levels (L1-L2, L2-L3, L3-L4, and L5-S1), vibration amplitudes of the disc bulge, von-Mises stress in annulus ground substance and intradiscal pressure also produced 4.2%-9.0%, 2.3%-8.9%, and 3.4%-8.8% deceases, respectively, after BPSF. After TLIF, application of BPSF can be helpful in the prevention of spine injury during vertical WBV. Copyright © 2018 Elsevier Inc. All rights reserved.

Detection of Atmospheric Carbon Dioxide from a Shuttle-Borne Lidar.

DTIC Science & Technology

1982-12-01

d, e_! *Pnl * cooling of the stratosphere. This will occur due to absorp- tion of the earth’s infrared radiation by CO2, and subse- quent emission of...and four vibrational modes. The available energy bands are a function of three vibrational quantum numbers describing the four vibrational modes: 1...insufficient to describe the energy levels based solely on three vibrational quantum numbers, and the rotational quantum number (J). Two additional .".,. 8

Development, Vibration, and Thermal Characterization of a Steady Operating Pulsed Power System for FRC Thrusters

DTIC Science & Technology

2015-04-01

to successfully operate after being exposed to the harsh launch vibration environment. 2. Uncover workmanship flaws such as loose fasteners or weak...uncover any workmanship errors in spite of exposing the PPUs to vibration levels in excess of what is expected for flight on any of the launchers ...successfully operate after being exposed to the harsh launch vibration environment. 2. Uncover workmanship flaws such as loose fasteners or weak

Visualizing the Vibration of Laryngeal Tissue during Phonation Using Ultrafast Plane Wave Ultrasonography.

PubMed

Jing, Bowen; Tang, Shanshan; Wu, Liang; Wang, Supin; Wan, Mingxi

2016-12-01

Ultrafast plane wave ultrasonography is employed in this study to visualize the vibration of the larynx and quantify the vibration phase as well as the vibration amplitude of the laryngeal tissue. Ultrasonic images were obtained at 5000 to 10,000 frames/s in the coronal plane at the level of the glottis. Although the image quality degraded when the imaging mode was switched from conventional ultrasonography to ultrafast plane wave ultrasonography, certain anatomic structures such as the vocal folds, as well as the sub- and supraglottic structures, including the false vocal folds, can be identified in the ultrafast plane wave ultrasonic image. The periodic vibration of the vocal fold edge could be visualized in the recorded image sequence during phonation. Furthermore, a motion estimation method was used to quantify the displacement of laryngeal tissue from hundreds of frames of ultrasonic data acquired. Vibratory displacement waveforms of the sub- and supraglottic structures were successfully obtained at a high level of ultrasonic signal correlation. Moreover, statistically significant differences in vibration pattern between the sub- and supraglottic structures were found. Variation of vibration amplitude along the subglottic mucosal surface is significantly smaller than that along the supraglottic mucosal surface. Phase delay of vibration along the subglottic mucosal surface is significantly smaller than that along the supraglottic mucosal surface. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

A Vibration Isolation System for Use in a Large Thermal Vacuum Test Facility

NASA Technical Reports Server (NTRS)

Hershfeld, Donald; VanCampen, Julie

2002-01-01

A thermal vacuum payload platform that is isolated from background vibration is required to support the development of future instruments for Hubble Space Telescope (HST) and the Next Generation Space Telescope (NGST) at the Goddard Space Flight Center (GSFC). Because of the size and weight of the thermal/vacuum facility in which the instruments are tested, it is not practical to isolate the entire facility externally. Therefore, a vibration isolation system has been designed and fabricated to be installed inside the chamber. The isolation system provides a payload interface of 3.05 m (10 feet) in diameter and is capable of supporting a maximum payload weight of 4536 kg (10,000 Lbs). A counterweight system has been included to insure stability of payloads having high centers of gravity. The vibration isolation system poses a potential problem in that leakage into the chamber could compromise the ability to maintain vacuum. Strict specifications were imposed on the isolation system design to minimize leakage. Vibration measurements, obtained inside the chamber, prior to installing the vibration isolation system, indicated levels in all axes of approximately 1 milli-g at about 20 Hz. The vibration isolation system was designed to provide a minimum attenuation of 40 dB to these levels. This paper describes the design and testing of this unique vibration isolation system. Problems with leakage and corrective methods are presented. Isolation performance results are also presented.

Input Shaping to Reduce Solar Array Structural Vibrations

NASA Technical Reports Server (NTRS)

Doherty, Michael J.; Tolson, Robert J.

1998-01-01

Structural vibrations induced by actuators can be minimized using input shaping. Input shaping is a feedforward method in which actuator commands are convolved with shaping functions to yield a shaped set of commands. These commands are designed to perform the maneuver while minimizing the residual structural vibration. In this report, input shaping is extended to stepper motor actuators. As a demonstration, an input-shaping technique based on pole-zero cancellation was used to modify the Solar Array Drive Assembly (SADA) actuator commands for the Lewis satellite. A series of impulses were calculated as the ideal SADA output for vibration control. These impulses were then discretized for use by the SADA stepper motor actuator and simulated actuator outputs were used to calculate the structural response. The effectiveness of input shaping is limited by the accuracy of the knowledge of the modal frequencies. Assuming perfect knowledge resulted in significant vibration reduction. Errors of 10% in the modal frequencies caused notably higher levels of vibration. Controller robustness was improved by incorporating additional zeros in the shaping function. The additional zeros did not require increased performance from the actuator. Despite the identification errors, the resulting feedforward controller reduced residual vibrations to the level of the exactly modeled input shaper and well below the baseline cases. These results could be easily applied to many other vibration-sensitive applications involving stepper motor actuators.

Vibration characteristics of OH-58A helicopter main rotor transmission

NASA Technical Reports Server (NTRS)

Lewicki, David G.; Coy, John J.

1987-01-01

Experimental vibration tests covering a range of torque and speed conditions were performed on the OH-58A helicopter main rotor transmission at the NASA Lewis Research Center. Signals from accelerometers located on the transmission housing were analyzed by using Fourier spectra, power spectral density functions, and averaging techniques. Most peaks of the Fourier spectra occurred at the spiral bevel and planetary gear mesh harmonics. The highest level of vibration occurred at the spiral bevel meshing frequency. Transmission speed and vibration measurement location had a significant effect on measured vibration; transmission torque and measurement direction had a small effect.

Tutorial: Novel properties of defects in semiconductors revealed by their vibrational spectra

NASA Astrophysics Data System (ADS)

Stavola, Michael; Fowler, W. Beall

2018-04-01

This is an introductory survey of the vibrational spectroscopy of defects in semiconductors that contain light-mass elements. The capabilities of vibrational spectroscopy for the identification of defects, the determination of their microscopic structures, and their dynamics are illustrated by a few examples. Several additional examples are discussed, with a focus on defects with properties not obviously accessible by vibrational spectroscopy, such as the diffusivity of an impurity, the negative U ordering of electronic levels, and the time constant for a nuclear-spin flip. These novel properties have, nonetheless, been revealed by vibrational spectra and their interpretation by theory.

A Resonant Damping Study Using Piezoelectric Materials

NASA Technical Reports Server (NTRS)

Min, J. B.; Duffy, K. P.; Choi, B. B.; Morrison, C. R.; Jansen, R. H.; Provenza, A. J.

2008-01-01

Excessive vibration of turbomachinery blades causes high cycle fatigue (HCF) problems requiring damping treatments to mitigate vibration levels. Based on the technical challenges and requirements learned from previous turbomachinery blade research, a feasibility study of resonant damping control using shunted piezoelectric patches with passive and active control techniques has been conducted on cantilever beam specimens. Test results for the passive damping circuit show that the optimum resistive shunt circuit reduces the third bending resonant vibration by almost 50%, and the optimum inductive circuit reduces the vibration by 90%. In a separate test, active control reduced vibration by approximately 98%.

Functional magnetic resonance imaging of the human spinal cord during vibration stimulation of different dermatomes.

PubMed

Lawrence, Jane M; Stroman, Patrick W; Kollias, Spyros S

2008-03-01

We investigated noninvasively areas of the healthy human spinal cord that become active in response to vibration stimulation of different dermatomes using functional magnetic resonance imaging (fMRI). The objectives of this study were to: (1) examine the patterns of consistent activity in the spinal cord during vibration stimulation of the skin, and (2) investigate the rostrocaudal distribution of active pixels when stimulation was applied to different dermatomes. FMRI of the cervical and lumbar spinal cord of seven healthy human subjects was carried out during vibration stimulation of six different dermatomes. In separate experiments, vibratory stimulation (about 50 Hz) was applied to the right biceps, wrist, palm, patella, Achilles tendon and left palm. The segmental distribution of activity observed by fMRI corresponded well with known spinal cord neuroanatomy. The peak number of active pixels was observed at the expected level of the spinal cord with some activity in the adjacent segments. The rostrocaudal distribution of activity was observed to correspond to the dermatome being stimulated. Cross-sectional localization of activity was primarily in dorsal areas but also spread into ventral and intermediate areas of the gray matter and a distinct laterality ipsilateral to the stimulated limb was not observed. We demonstrated that fMRI can detect a dermatome-dependent pattern of spinal cord activity during vibratory stimulation and can be used as a passive stimulus for the noninvasive assessment of the functional integrity of the human spinal cord. Demonstration of cross-sectional selectivity of the activation awaits further methodological and experimental refinements.

Optimized energy harvesting from mechanical vibrations through piezoelectric actuators, based on a synchronized switching technique

NASA Astrophysics Data System (ADS)

Tsampas, P.; Roditis, G.; Papadimitriou, V.; Chatzakos, P.; Gan, Tat-Hean

2013-05-01

Increasing demand in mobile, autonomous devices has made energy harvesting a particular point of interest. Systems that can be powered up by a few hundreds of microwatts could feature their own energy extraction module. Energy can be harvested from the environment close to the device. Particularly, the ambient mechanical vibrations conversion via piezoelectric transducers is one of the most investigated fields for energy harvesting. A technique for optimized energy harvesting using piezoelectric actuators called "Synchronized Switching Harvesting" is explored. Comparing to a typical full bridge rectifier, the proposed harvesting technique can highly improve harvesting efficiency, even in a significantly extended frequency window around the piezoelectric actuator's resonance. In this paper, the concept of design, theoretical analysis, modeling, implementation and experimental results using CEDRAT's APA 400M-MD piezoelectric actuator are presented in detail. Moreover, we suggest design guidelines for optimum selection of the storage unit in direct relation to the characteristics of the random vibrations. From a practical aspect, the harvesting unit is based on dedicated electronics that continuously sense the charge level of the actuator's piezoelectric element. When the charge is sensed, to come to a maximum, it is directed to speedily flow into a storage unit. Special care is taken so that electronics operate at low voltages consuming a very small amount of the energy stored. The final prototype developed includes the harvesting circuit implemented with miniaturized, low cost and low consumption electronics and a storage unit consisting of a super capacitors array, forming a truly self-powered system drawing energy from ambient random vibrations of a wide range of characteristics.

The influence of the great Hanshin earthquake on human response to environmental vibration due to the Shinkansen.

PubMed

Sumitomo, S; Tsujimoto, S; Maeda, S; Kitamura, Y

1998-07-01

A severe earthquake of magnitude 7.2 hit the west part of Japan on January 17, 1995. A part of the Shinkansen railway, which is one of the most popular high-speed mass transportation systems in Japan, was seriously damaged by the earthquake. About 80 days later, the Shinkansen service was resumed but complaints about vibration due to the passing Shinkansen increased rapidly among residents near the tracks. This paper reports the results of two investigations that were carried out in both stricken and non-stricken areas to determine the cause of complaint. In the first investigation, the ground vibration propagation induced by passing trains was measured. In the second investigation, questionnaires were distributed to the people living near the Shinkansen tracks. As a result, it was found out that the vibration levels before and after the earthquake were almost the same at most measured points in the stricken area. It was also found that the vibration levels in the stricken area and a non-stricken area were almost the same within 50 m from the Shinkansen tracks. However the results of the questionnaire survey showed that people's nuisance due to the vibration in the stricken area was clearly greater than that in the non-stricken area. This inconsistency was explained using the "category judgment method", which is generally used to determine the relationship between a physical stimulus and psychological reaction. According to the results of this analysis, the vibration level, at which 50% of the inhabitants complained about Shinkansen vibration, was approximately 54 dB in the non-stricken area and 50 dB in the stricken area. This result suggests that the people who experienced the severe earthquake became 4 dB more sensitive to the Shinkansen vibration than the people living in a non-stricken area despite the fact that this investigation was carried out 10 months after the earthquake struck.

Dissociation energy and dynamics of water clusters

NASA Astrophysics Data System (ADS)

Ch'ng, Lee Chiat

The state-to-state vibrational predissociation (VP) dynamics of water clusters were studied following excitation of a vibrational mode of each cluster. Velocity-map imaging (VMI) and resonance-enhanced multiphoton ionization (REMPI) were used to determine pair-correlated center-of-mass translational energy distributions. Product energy distributions and dissociation energies were determined. Following vibrational excitation of the HCl stretch fundamental of the HCl-H2O dimer, HCl fragments were detected by 2 + 1 REMPI via the f 3□2(nu' = 0) ← X 1Sigma+(nu'' = 0) and V1Sigma + (nu' = 11 and 12) ← X1Sigma+ (nu'' = 0) transitions. REMPI spectra clearly show HCl from dissociation produced in the ground vibrational state with J'' up to 11. The fragments' center-of-mass translational energy distributions were determined from images of selected rotational states of HCl and were converted to rotational state distributions of the water cofragment. All the distributions could be fit well when using a dimer dissociation energy of bond dissociation energy D0 = 1334 +/- 10 cm--1. The rotational distributions in the water cofragment pair-correlated with specific rotational states of HCl appear nonstatistical when compared to predictions of the statistical phase space theory. A detailed analysis of pair-correlated state distributions was complicated by the large number of water rotational states available, but the data show that the water rotational populations increase with decreasing translational energy. H2O fragments of this dimer were detected by 2 + 1 REMPI via the C˜1B1(000) ← X˜1A1(000) transition. REMPI clearly shows that H2O from dissociation is produced in the ground vibrational state. The fragment's center-of-mass translational energy distributions were determined from images of selected rotational states of H2O and were converted to rotational state distributions of the HCl cofragment. The distributions gave D0 = 1334 +/- 10 cm --1 and show a clear preference for rotational levels in the HCl fragment that minimize translational energy release. The usefulness of 2 + 1 REMPI detection of water fragment is discussed. The hydrogen bonding in water is dominated by pair-wise dimer interactions, and the predissociation of the water dimer following vibrational excitation is reported. The measured D0 values of (H 2O)2 and (D2O)2, 1105 and 1244 +/- 10 cm--1, respectively, are in excellent agreement with the calculated values of 1103 and 1244 +/- 5 cm--1. Pair-correlated water fragment rovibrational state distributions following vibrational predissociation of (H2O)2 and (D2O) 2 were obtained upon excitation of the hydrogen bonded OH and OD stretch fundamentals, respectively. Quasiclassical trajectory calculations, using an accurate full-dimensional potential energy surface, are in accord with and help to elucidate experiment. Experiment and theory find predominant excitation of the fragment bending mode upon hydrogen bond breaking. A minor channel is also observed in which both fragments are in the ground vibrational state and are highly rotationally excited. The theoretical calculations reveal equal probability of bending excitation in the donor and acceptor subunits, which is a result of interchange of donor and acceptor roles. The rotational distributions associated with the major channel, in which one water fragment has one quantum of bend, and the minor channel with both water fragments in the ground vibrational state are calculated, and are in agreement with experiment. (Abstract shortened by UMI.)

Ab initio and density functional computations of the vibrational spectrum, molecular geometry and some molecular properties of the antidepressant drug sertraline (Zoloft) hydrochloride

NASA Astrophysics Data System (ADS)

Sagdinc, Seda; Kandemirli, Fatma; Bayari, Sevgi Haman

2007-02-01

Sertraline hydrochloride is a highly potent and selective inhibitor of serotonin (5HT). It is a basic compound of pharmaceutical application for antidepressant treatment (brand name: Zoloft). Ab initio and density functional computations of the vibrational (IR) spectrum, the molecular geometry, the atomic charges and polarizabilities were carried out. The infrared spectrum of sertraline is recorded in the solid state. The observed IR wave numbers were analysed in light of the computed vibrational spectrum. On the basis of the comparison between calculated and experimental results and the comparison with related molecules, assignments of fundamental vibrational modes are examined. The X-ray geometry and experimental frequencies are compared with the results of our theoretical calculations.

Vibration-based photoacoustic tomography

NASA Astrophysics Data System (ADS)

Li, Rui; Rajian, Justin R.; Wang, Pu; Slipchenko, Mikhail N.; Cheng, Ji-Xin

2013-03-01

Photoacoustic imaging employing molecular overtone vibration as contrast mechanism opens a new avenue for deep tissue imaging with chemical bond selectivity. Here, we demonstrate vibration-based photoacoustic tomography with an imaging depth on the centimeter scale. To provide sufficient pulse energy at the overtone transition wavelengths, we constructed a compact, barium nitrite crystal-based Raman laser for excitation of 2nd overtone of C-H bond. Using a 5-ns Nd:YAG laser as pumping source, up to 105 mJ pulse energy at 1197 nm was generated. Vibrational photoacoutic spectroscopy and tomography of phantom (polyethylene tube) immersed in whole milk was performed. With a pulse energy of 47 mJ on the milk surface, up to 2.5 cm penetration depth was reached with a signal-to-noise ratio of 12.

Anharmonic frequencies of CX2Y2 (X, Y = O, N, F, H, D) isomers and related systems obtained from vibrational multiconfiguration self-consistent field theory.

PubMed

Pfeiffer, Florian; Rauhut, Guntram

2011-10-13

Accurate anharmonic frequencies are provided for molecules of current research, i.e., diazirines, diazomethane, the corresponding fluorinated and deuterated compounds, their dioxygen analogs, and others. Vibrational-state energies were obtained from state-specific vibrational multiconfiguration self-consistent field theory (VMCSCF) based on multilevel potential energy surfaces (PES) generated from explicitly correlated coupled cluster, CCSD(T)-F12a, and double-hybrid density functional calculations, B2PLYP. To accelerate the vibrational structure calculations, a configuration selection scheme as well as a polynomial representation of the PES have been exploited. Because experimental data are scarce for these systems, many calculated frequencies of this study are predictions and may guide experiments to come.

Linear and nonlinear analysis of fluid slosh dampers

NASA Astrophysics Data System (ADS)

Sayar, B. A.; Baumgarten, J. R.

1982-11-01

A vibrating structure and a container partially filled with fluid are considered coupled in a free vibration mode. To simplify the mathematical analysis, a pendulum model to duplicate the fluid motion and a mass-spring dashpot representing the vibrating structure are used. The equations of motion are derived by Lagrange's energy approach and expressed in parametric form. For a wide range of parametric values the logarithmic decrements of the main system are calculated from theoretical and experimental response curves in the linear analysis. However, for the nonlinear analysis the theoretical and experimental response curves of the main system are compared. Theoretical predictions are justified by experimental observations with excellent agreement. It is concluded finally that for a proper selection of design parameters, containers partially filled with viscous fluids serve as good vibration dampers.

Survey of Technical Preventative Measures to Reduce Whole-Body Vibration Effects when Designing Mobile Machinery

NASA Astrophysics Data System (ADS)

DONATI, P.

2002-05-01

Engineering solutions to minimize the effects on operators of vibrating mobile machinery can be conveniently grouped into three areas: Reduction of vibration at source by improvement of the quality of terrain, careful selection of vehicle or machine, correct loading, proper maintenance, etc.Reduction of vibration transmission by incorporating suspension systems (tyres, vehicle suspensions, suspension cab and seat) between the operator and the source of vibration.Improvement of cab ergonomics and seat profiles to optimize operator posture. These paper reviews the different techniques and problems linked to categories (2) and (3). According to epidemiological studies, the main health risk with whole-body vibration exposure would appear to be lower back pain. When designing new mobile machinery, all factors which may contribute to back injury should be considered in order to reduce risk. For example, optimized seat suspension is useless if the suspension seat cannot be correctly and easily adjusted to the driver's weight or if the driver is forced to drive in a bent position to avoid his head striking the ceiling due to the spatial requirement of the suspension seat.

The fundamental role of quantized vibrations in coherent light harvesting by cryptophyte algae

NASA Astrophysics Data System (ADS)

Kolli, Avinash; O'Reilly, Edward J.; Scholes, Gregory D.; Olaya-Castro, Alexandra

2012-11-01

The influence of fast vibrations on energy transfer and conversion in natural molecular aggregates is an issue of central interest. This article shows the important role of high-energy quantized vibrations and their non-equilibrium dynamics for energy transfer in photosynthetic systems with highly localized excitonic states. We consider the cryptophyte antennae protein phycoerythrin 545 and show that coupling to quantized vibrations, which are quasi-resonant with excitonic transitions is fundamental for biological function as it generates non-cascaded transport with rapid and wider spatial distribution of excitation energy. Our work also indicates that the non-equilibrium dynamics of such vibrations can manifest itself in ultrafast beating of both excitonic populations and coherences at room temperature, with time scales in agreement with those reported in experiments. Moreover, we show that mechanisms supporting coherent excitonic dynamics assist coupling to selected modes that channel energy to preferential sites in the complex. We therefore argue that, in the presence of strong coupling between electronic excitations and quantized vibrations, a concrete and important advantage of quantum coherent dynamics is precisely to tune resonances that promote fast and effective energy distribution.

Vibration perception threshold for sight-threatening retinopathy screening in type 2 diabetic outpatients.

PubMed

Shen, Jing; Hu, Yanyun; Liu, Fang; Zeng, Hui; Li, Lianxi; Zhao, Jun; Zhao, Jungong; Zheng, Taishan; Lu, Huijuan; Lu, Fengdi; Bao, Yuqian; Jia, Weiping

2013-10-01

We investigated the relationship between vibration perception threshold and diabetic retinopathy and verified the screening value of vibration perception threshold for severe diabetic retinopathy. A total of 955 patients with type 2 diabetes were recruited and divided into three groups according to their fundus oculi photography results: no diabetic retinopathy (n = 654, 68.48%), non-sight-threatening diabetic retinopathy (n = 189, 19.79%) and sight-threatening diabetic retinopathy (n = 112, 11.73%). Their clinical and biochemical characteristics, vibration perception threshold and the diabetic retinopathy grades were detected and compared. There were significant differences in diabetes duration and blood glucose levels among three groups (all p < 0.05). The values of vibration perception threshold increased with the rising severity of retinopathy, and the vibration perception threshold level of sight-threatening diabetic retinopathy group was significantly higher than both non-sight-threatening diabetic retinopathy and no diabetic retinopathy groups (both p < 0.01). The prevalence of sight-threatening diabetic retinopathy in vibration perception threshold >25 V group was significantly higher than those in 16-24 V group (p < 0.01). The severity of diabetic retinopathy was positively associated with diabetes duration, blood glucose indexes and vibration perception threshold (all p < 0.01). Multiple stepwise regression analysis proved that glycosylated haemoglobin (β = 0.385, p = 0.000), diabetes duration (β = 0.275, p = 0.000) and vibration perception threshold (β = 0.180, p = 0.015) were independent risk factors for diabetic retinopathy. Receiver operating characteristic analysis further revealed that vibration perception threshold higher than 18 V was the optimal cut point for reflecting high risk of sight-threatening diabetic retinopathy (odds ratio = 4.20, 95% confidence interval = 2.67-6.59). There was a close association between vibration perception threshold and the severity of diabetic retinopathy. vibration perception threshold was a potential screening method for diabetic retinopathy, and its optimal cut-off for prompting high risk of sight-threatening retinopathy was 18 V. Copyright © 2013 John Wiley & Sons, Ltd.

A two scale modeling and computational framework for vibration-induced Raynaud syndrome.

PubMed

Hua, Yue; Lemerle, Pierre; Ganghoffer, Jean-François

2017-07-01

Hand-Arm Vibration syndrome (HAVS), usually caused by long-term use of hand-held power tools, can in certain manifestations alter the peripheral blood circulation in the hand-arm region. HAVS typically occurs after exposure to cold, causing an abnormally strong vasoconstriction of blood vessels. A pathoanatomical mechanism suggests that a reduction of the lumen of the blood vessels in VWF (Vibration White Finger) subjects, due to either hypertrophy or thickening of the vessel wall, may be at the origin of the disease. However, the direct and indirect effects of the load of the hand-held tools on the structure of blood vessels remain controversial:.one hypothesis is the mechanical action of vibration on the local acral dysregulation and/or on the vessel histomorphological modifications. Another hypothesis is the participation of the sympathetic nervous system to this dysregulation. In this paper, we assume the modifications as mechanobiological growth and the load-effect relationship may be interpreted as directly or indirectly induced. This work is the first attempt to model the effect of vibration through soft tissues onto the distal capillaries, addressing the double paradigm of multi space-time scales, i.e. low period vibration versus high time constant of the growth phenomenon as well as vibrations propagating in the macroscopic tissue including the microscopic capillary structures subjected to a pathological microstructural evolution. The objective is to lay down the theoretical basis of growth modeling for the small distal artery, with the ability to predict the geometrical and structural changes of the arterial walls caused by vibration exposure. We adopt the key idea of splitting the problem into one global vibration problem at the macroscopic scale and one local growth problem at the micro level. The macroscopic hyperelastic viscous dynamic model of the fingertip cross-section is validated by fitting experimental data. It is then used in steady-state vibration conditions to predict the mechanical fields in the close vicinity of capillaries. The space scale transfer from macroscopic to microscopic levels is ensured by considering a representative volume element (RVE) embedding a single capillary in its center. The vibrations emitted by the hand held power tool are next linked to the capillary growth through the adopted biomechanical growth model at the capillary level. The obtained results show that vibrations induce an increase of the thickness of the capillary's wall, thereby confirming the scenario of vibrations induced reduction of the lumen of blood vessels. Copyright © 2017 Elsevier Ltd. All rights reserved.

Application of level set method to optimal vibration control of plate structures

NASA Astrophysics Data System (ADS)

Ansari, M.; Khajepour, A.; Esmailzadeh, E.

2013-02-01

Vibration control plays a crucial role in many structures, especially in the lightweight ones. One of the most commonly practiced method to suppress the undesirable vibration of structures is to attach patches of the constrained layer damping (CLD) onto the surface of the structure. In order to consider the weight efficiency of a structure, the best shapes and locations of the CLD patches should be determined to achieve the optimum vibration suppression with minimum usage of the CLD patches. This paper proposes a novel topology optimization technique that can determine the best shape and location of the applied CLD patches, simultaneously. Passive vibration control is formulated in the context of the level set method, which is a numerical technique to track shapes and locations concurrently. The optimal damping set could be found in a structure, in its fundamental vibration mode, such that the maximum modal loss factor of the system is achieved. Two different plate structures will be considered and the damping patches will be optimally located on them. At the same time, the best shapes of the damping patches will be determined too. In one example, the numerical results will be compared with those obtained from the experimental tests to validate the accuracy of the proposed method. This comparison reveals the effectiveness of the level set approach in finding the optimum shape and location of the CLD patches.

Theoretical study of the vibrational relaxation of the methyl radical in collisions with helium

NASA Astrophysics Data System (ADS)

Ma, Qianli; Dagdigian, Paul J.; Alexander, Millard H.

2013-03-01

We report a theoretical investigation of the relaxation of the umbrella vibrational mode (the ν2 mode) of the CH3 molecule in its ground tilde{X}^2A_2^' ' } electronic state in collisions with helium. We have calculated a four-dimensional potential energy surface (PES) for the interaction between CH3 with different umbrella displacements and a helium atom, using a restricted open-shell coupled-cluster method with inclusion of all single, double, and (perturbatively) triple excitations [RCCSD(T)]. With this PES we carried out full close-coupling scattering calculations including all CH3 umbrella-rotational levels with v2 ⩽ 3. To our knowledge, this work represents the first fully quantum calculations of ro-vibrational relaxation of a polyatomic. In more detail, we investigate propensities in the calculated ro-vibrational cross sections and the dependence on initial rotational excitation, as well as determining thermal rate constants. Overall, ro-vibrational relaxation is nearly two orders of magnitude less efficient than pure-rotational relaxation, with a noticeable dependence on the initial rotational level. We predict the room temperature v2 = 1 vibrational relaxation rate constant to be 5.4 × 10-12 cm3 molecule-1 s-1, compared to the rate constants for pure-rotational relaxation of the lower rotational levels (˜2.0 × 10-10 cm3 molecule-1 s-1).

Municipal waste processing apparatus

DOEpatents

Mayberry, John L.

1988-01-01

Municipal waste materials are processed by crushing the materials so that pieces of noncombustible material are smaller than a selected size and pieces of combustible material are larger than the selected size. The crushed materials are placed on a vibrating mesh screen conveyor belt having openings which pass the smaller, noncombustible pieces of material, but do not pass the larger, combustible pieces of material. Pieces of material which become lodged in the openings of the conveyor belt may be removed by cylindrical deraggers or pressurized air. The crushed materials may be fed onto the conveyor belt by a vibrating feed plate which shakes the materials so that they tend to lie flat.

Laser isotope separation by multiple photon absorption

DOEpatents

Robinson, C.P.; Rockwood, S.D.; Jensen, R.J.; Lyman, J.L.; Aldridge, J.P. III.

1987-04-07

Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO[sub 2] laser light may be used to highly enrich [sup 34]S in natural SF[sub 6] and [sup 11]B in natural BCl[sub 3]. 8 figs.

Sensing site-specific structural characteristics and chirality using vibrational circular dichroism of isotope labeled peptides.

PubMed

Keiderling, Timothy A

2017-12-01

Isotope labeling has a long history in chemistry as a tool for probing structure, offering enhanced sensitivity, or enabling site selection with a wide range of spectroscopic tools. Chirality sensitive methods such as electronic circular dichroism are global structural tools and have intrinsically low resolution. Consequently, they are generally insensitive to modifications to enhance site selectivity. The use of isotope labeling to modify vibrational spectra with unique resolvable frequency shifts can provide useful site-specific sensitivity, and these methods have been recently more widely expanded in biopolymer studies. While the spectral shifts resulting from changes in isotopic mass can provide resolution of modes from specific parts of the molecule and can allow detection of local change in structure with perturbation, these shifts alone do not directly indicate structure or chirality. With vibrational circular dichroism (VCD), the shifted bands and their resultant sign patterns can be used to indicate local conformations in labeled biopolymers, particularly if multiple labels are used and if their coupling is theoretically modeled. This mini-review discusses selected examples of the use of labeling specific amides in peptides to develop local structural insight with VCD spectra. © 2017 Wiley Periodicals, Inc.

Dynamic Analysis of Heavy Vehicle Medium Duty Drive Shaft Using Conventional and Composite Material

NASA Astrophysics Data System (ADS)

Kumar, Ashwani; Jain, Rajat; Patil, Pravin P.

2016-09-01

The main highlight of this study is structural and modal analysis of single piece drive shaft for selection of material. Drive shaft is used for torque carrying from vehicle transmission to rear wheel differential system. Heavy vehicle medium duty transmission drive shaft was selected as research object. Conventional materials (Steel SM45 C, Stainless Steel) and composite materials (HS carbon epoxy, E Glass Polyester Resin Composite) were selected for the analysis. Single piece composite material drive shaft has advantage over conventional two-piece steel drive shaft. It has higher specific strength, longer life, less weight, high critical speed and higher torque carrying capacity. The main criteria for drive shaft failure are strength and weight. Maximum modal frequency obtained is 919 Hz. Various harmful vibration modes (lateral vibration and torsional vibration) were identified and maximum deflection region was specified. For single-piece drive shaft the natural bending frequency should be higher because it is subjected to torsion and shear stress. Single piece drive shaft was modelled using Solid Edge and Pro-E. Finite Element Analysis was used for structural and modal analysis with actual running boundary condition like frictional support, torque and moment. FEA simulation results were validated with experimental literature results.

Low-lying vibronic level structure of the ground state of the methoxy radical: Slow electron velocity-map imaging (SEVI) spectra and Köppel-Domcke-Cederbaum (KDC) vibronic Hamiltonian calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weichman, Marissa L.; Cheng, Lan; Kim, Jongjin B.

A joint experimental and theoretical study is reported on the low-lying vibronic level structure of the ground state of the methoxy radical using slow photoelectron velocity-map imaging spectroscopy of cryogenically cooled, mass-selected anions (cryo-SEVI) and Köppel-Domcke-Cederbaum (KDC) vibronic Hamiltonian calculations. The KDC vibronic model Hamiltonian in the present study was parametrized using high-level quantum chemistry, allowing the assignment of the cryo-SEVI spectra for vibronic levels of CH 3O up to 2000 cm –1 and of CD 3O up to 1500 cm –1 above the vibrational origin, using calculated vibronic wave functions. The adiabatic electron affinities of CH 3O and CDmore » 3O are determined from the cryo-SEVI spectra to be 1.5689 ± 0.0007 eV and 1.5548 ± 0.0007 eV, respectively, demonstrating improved precision compared to previous work. Experimental peak splittings of <10 cm –1 are resolved between the e 1/2 and e 3/2 components of the 6 1 and 5 1 vibronic levels. A pair of spin-vibronic levels at 1638 and 1677 cm –1 were predicted in the calculation as the e 1/2 and e 3/2 components of 6 2 levels and experimentally resolved for the first time. The strong variation of the spin-orbit splittings with a vibrational quantum number is in excellent agreement between theory and experiment. In conclusion, the observation of signals from nominally forbidden a 1 vibronic levels in the cryo-SEVI spectra also provides direct evidence of vibronic coupling between ground and electronically excited states of methoxy.« less

Low-lying vibronic level structure of the ground state of the methoxy radical: Slow electron velocity-map imaging (SEVI) spectra and Köppel-Domcke-Cederbaum (KDC) vibronic Hamiltonian calculations

DOE PAGES

Weichman, Marissa L.; Cheng, Lan; Kim, Jongjin B.; ...

2017-06-12

A joint experimental and theoretical study is reported on the low-lying vibronic level structure of the ground state of the methoxy radical using slow photoelectron velocity-map imaging spectroscopy of cryogenically cooled, mass-selected anions (cryo-SEVI) and Köppel-Domcke-Cederbaum (KDC) vibronic Hamiltonian calculations. The KDC vibronic model Hamiltonian in the present study was parametrized using high-level quantum chemistry, allowing the assignment of the cryo-SEVI spectra for vibronic levels of CH 3O up to 2000 cm –1 and of CD 3O up to 1500 cm –1 above the vibrational origin, using calculated vibronic wave functions. The adiabatic electron affinities of CH 3O and CDmore » 3O are determined from the cryo-SEVI spectra to be 1.5689 ± 0.0007 eV and 1.5548 ± 0.0007 eV, respectively, demonstrating improved precision compared to previous work. Experimental peak splittings of <10 cm –1 are resolved between the e 1/2 and e 3/2 components of the 6 1 and 5 1 vibronic levels. A pair of spin-vibronic levels at 1638 and 1677 cm –1 were predicted in the calculation as the e 1/2 and e 3/2 components of 6 2 levels and experimentally resolved for the first time. The strong variation of the spin-orbit splittings with a vibrational quantum number is in excellent agreement between theory and experiment. In conclusion, the observation of signals from nominally forbidden a 1 vibronic levels in the cryo-SEVI spectra also provides direct evidence of vibronic coupling between ground and electronically excited states of methoxy.« less

Statistical evaluation of vibration analysis techniques

NASA Technical Reports Server (NTRS)

Milner, G. Martin; Miller, Patrice S.

1987-01-01

An evaluation methodology is presented for a selection of candidate vibration analysis techniques applicable to machinery representative of the environmental control and life support system of advanced spacecraft; illustrative results are given. Attention is given to the statistical analysis of small sample experiments, the quantification of detection performance for diverse techniques through the computation of probability of detection versus probability of false alarm, and the quantification of diagnostic performance.

Vibrational relaxation and internal conversion in the overlapped optically-allowed 1Bu+ and optically-forbidden 1Bu- or 3Ag- vibronic levels of carotenoids: Effects of diabatic mixing as determined by Kerr-gate fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Kakitani, Yoshinori; Miki, Takeshi; Koyama, Yasushi; Nagae, Hiroyoshi; Nakamura, Ryosuke; Kanematsu, Yasuo

2009-07-01

The time constants of the vibrational relaxation, υ = 2 → υ = 1 and υ = 1 → υ = 0, in the 1Bu+ manifold and those of internal conversion from the 1Bu+(0) level, which is isoenergetic (so-called 'diabatic') with the 1Bu- vibronic levels in neurosporene and spheroidene and with the 3Ag- vibronic levels in lycopene and anhydrorhodovibrin, were determined by Kerr-gate fluorescence spectroscopy. The time constants of the vibrational relaxation were in the ˜1:2 ratio, and those of internal conversion agreed with the lifetimes of the diabatic counterparts, i.e., the 1Bu- and 3Ag- electronic states, respectively.

New analytical model for the ozone electronic ground state potential surface and accurate ab initio vibrational predictions at high energy range.

PubMed

Tyuterev, Vladimir G; Kochanov, Roman V; Tashkun, Sergey A; Holka, Filip; Szalay, Péter G

2013-10-07

An accurate description of the complicated shape of the potential energy surface (PES) and that of the highly excited vibration states is of crucial importance for various unsolved issues in the spectroscopy and dynamics of ozone and remains a challenge for the theory. In this work a new analytical representation is proposed for the PES of the ground electronic state of the ozone molecule in the range covering the main potential well and the transition state towards the dissociation. This model accounts for particular features specific to the ozone PES for large variations of nuclear displacements along the minimum energy path. The impact of the shape of the PES near the transition state (existence of the "reef structure") on vibration energy levels was studied for the first time. The major purpose of this work was to provide accurate theoretical predictions for ozone vibrational band centres at the energy range near the dissociation threshold, which would be helpful for understanding the very complicated high-resolution spectra and its analyses currently in progress. Extended ab initio electronic structure calculations were carried out enabling the determination of the parameters of a minimum energy path PES model resulting in a new set of theoretical vibrational levels of ozone. A comparison with recent high-resolution spectroscopic data on the vibrational levels gives the root-mean-square deviations below 1 cm(-1) for ozone band centres up to 90% of the dissociation energy. New ab initio vibrational predictions represent a significant improvement with respect to all previously available calculations.

Frequency identification of vibration signals using video camera image data.

PubMed

Jeng, Yih-Nen; Wu, Chia-Hung

2012-10-16

This study showed that an image data acquisition system connecting a high-speed camera or webcam to a notebook or personal computer (PC) can precisely capture most dominant modes of vibration signal, but may involve the non-physical modes induced by the insufficient frame rates. Using a simple model, frequencies of these modes are properly predicted and excluded. Two experimental designs, which involve using an LED light source and a vibration exciter, are proposed to demonstrate the performance. First, the original gray-level resolution of a video camera from, for instance, 0 to 256 levels, was enhanced by summing gray-level data of all pixels in a small region around the point of interest. The image signal was further enhanced by attaching a white paper sheet marked with a black line on the surface of the vibration system in operation to increase the gray-level resolution. Experimental results showed that the Prosilica CV640C CMOS high-speed camera has the critical frequency of inducing the false mode at 60 Hz, whereas that of the webcam is 7.8 Hz. Several factors were proven to have the effect of partially suppressing the non-physical modes, but they cannot eliminate them completely. Two examples, the prominent vibration modes of which are less than the associated critical frequencies, are examined to demonstrate the performances of the proposed systems. In general, the experimental data show that the non-contact type image data acquisition systems are potential tools for collecting the low-frequency vibration signal of a system.

Frequency Identification of Vibration Signals Using Video Camera Image Data

PubMed Central

Jeng, Yih-Nen; Wu, Chia-Hung

2012-01-01

This study showed that an image data acquisition system connecting a high-speed camera or webcam to a notebook or personal computer (PC) can precisely capture most dominant modes of vibration signal, but may involve the non-physical modes induced by the insufficient frame rates. Using a simple model, frequencies of these modes are properly predicted and excluded. Two experimental designs, which involve using an LED light source and a vibration exciter, are proposed to demonstrate the performance. First, the original gray-level resolution of a video camera from, for instance, 0 to 256 levels, was enhanced by summing gray-level data of all pixels in a small region around the point of interest. The image signal was further enhanced by attaching a white paper sheet marked with a black line on the surface of the vibration system in operation to increase the gray-level resolution. Experimental results showed that the Prosilica CV640C CMOS high-speed camera has the critical frequency of inducing the false mode at 60 Hz, whereas that of the webcam is 7.8 Hz. Several factors were proven to have the effect of partially suppressing the non-physical modes, but they cannot eliminate them completely. Two examples, the prominent vibration modes of which are less than the associated critical frequencies, are examined to demonstrate the performances of the proposed systems. In general, the experimental data show that the non-contact type image data acquisition systems are potential tools for collecting the low-frequency vibration signal of a system. PMID:23202026

Ambient Vibration Tests of an Arch Dam with Different Reservoir Water Levels: Experimental Results and Comparison with Finite Element Modelling

PubMed Central

Ranieri, Gaetano

2014-01-01

This paper deals with the ambient vibration tests performed in an arch dam in two different working conditions in order to assess the effect produced by two different reservoir water levels on the structural vibration properties. The study consists of an experimental part and a numerical part. The experimental tests were carried out in two different periods of the year, at the beginning of autumn (October 2012) and at the end of winter (March 2013), respectively. The measurements were performed using a fast technique based on asynchronous records of microtremor time-series. In-contact single-station measurements were done by means of one single high resolution triaxial tromometer and two low-frequency seismometers, placed in different points of the structure. The Standard Spectral Ratio method has been used to evaluate the natural frequencies of vibration of the structure. A 3D finite element model of the arch dam-reservoir-foundation system has been developed to verify analytically determined vibration properties, such as natural frequencies and mode shapes, and their changes linked to water level with the experimental results. PMID:25003146

Vibrational dynamics in dendridic oligoarylamines by Raman spectroscopy and incoherent inelastic neutron scattering.

PubMed

Kulszewicz-Bajer, Irena; Louarn, Guy; Djurado, David; Skorka, Lukasz; Szymanski, Marek; Mevellec, Jean Yves; Rols, Stephane; Pron, Adam

2014-05-15

Vibrational dynamics in triarylamine dendrimers was studied in a complementary way by Raman and infrared (IR) spectroscopies and incoherent inelastic neutron scattering (IINS). Three molecules were investigated, namely, unsubstituted triarylamine dendrimer of the first generation and two dendrimers of the first and second generation, substituted in the crown with butyl groups. To facilitate the assignment of the observed IR and Raman modes as well as the IINS peaks, vibrational models, based on the general valence force field method (GVFF), were calculated for all three compounds studied. A perfect consistency between the calculated and experimental results was found. Moreover, an important complementarity of the vibrational spectroscopies and IINS was established for the investigated dendrimers. The IINS peaks originating mainly from the C-H motions were not restricted by particular selection rules and only dependent on the IINS cross section. To the contrary, Raman and IR bands were imposed by the selection rules and the local geometry of the dendrimers yielding mainly C-C and C-N deformation modes with those of C-H nature of much lower intensity. Raman spectroscopy was also applied to the studies of the oxidation of dendrimers to their cationic forms. A strong Raman resonance effect was observed, since the spectra of the studied compounds, registered at different levels of their oxidation, strongly depended on the position of the excitation line with respect to their electronic spectrum. In particular, the blue (458 nm) excitation line turned out to be insensitive toward the cationic forms yielding very limited spectral information. To the contrary, the use of the red (647 nm) and infrared (1064 nm) excitation lines allowed for an unambiguous monitoring of the spectral changes in dendrimers oxidized to nominally monocationic and tricationic states. The analysis of oxidation-induced spectral changes in the tricationic state indicated that the charge storage configuration predominantly involved one spinless dication of the quinoid bond sequence and one radical cation. However, small numbers of dications were also found in a nominally monocationic state, where only radical cations should have been present. This finding was indicative of some inhomogeneity of the oxidation.

The relationships between hand coupling force and vibration biodynamic responses of the hand-arm system.

PubMed

Pan, Daniel; Xu, Xueyan S; Welcome, Daniel E; McDowell, Thomas W; Warren, Christopher; Wu, John; Dong, Ren G

2018-06-01

This study conducted two series of experiments to investigate the relationships between hand coupling force and biodynamic responses of the hand-arm system. In the first experiment, the vibration transmissibility on the system was measured as a continuous function of grip force while the hand was subjected to discrete sinusoidal excitations. In the second experiment, the biodynamic responses of the system subjected to a broadband random vibration were measured under five levels of grip forces and a combination of grip and push forces. This study found that the transmissibility at each given frequency increased with the increase in the grip force before reaching a maximum level. The transmissibility then tended to plateau or decrease when the grip force was further increased. This threshold force increased with an increase in the vibration frequency. These relationships remained the same for both types of vibrations. The implications of the experimental results are discussed. Practitioner Summary: Shocks and vibrations transmitted to the hand-arm system may cause injuries and disorders of the system. How to take hand coupling force into account in the risk assessment of vibration exposure remains an important issue for further studies. This study is designed and conducted to help resolve this issue.

49 CFR Appendix C to Part 173 - Procedure for Base-level Vibration Testing

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 2 2014-10-01 2014-10-01 false Procedure for Base-level Vibration Testing C Appendix C to Part 173 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS...-GENERAL REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Pt. 173, App. C Appendix C to Part 173—Procedure for...

49 CFR Appendix C to Part 173 - Procedure for Base-level Vibration Testing

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 2 2011-10-01 2011-10-01 false Procedure for Base-level Vibration Testing C Appendix C to Part 173 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS...-GENERAL REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Pt. 173, App. C Appendix C to Part 173—Procedure for...

Kinetics of highly vibrationally excited O2(X) molecules in inductively-coupled oxygen plasmas

NASA Astrophysics Data System (ADS)

Annušová, Adriana; Marinov, Daniil; Booth, Jean-Paul; Sirse, Nishant; Lino da Silva, Mário; Lopez, Bruno; Guerra, Vasco

2018-04-01

The high degree of vibrational excitation of O2 ground state molecules recently observed in inductively coupled plasma discharges is investigated experimentally in more detail and interpreted using a detailed self-consistent 0D global kinetic model for oxygen plasmas. Additional experimental results are presented and used to validate the model. The vibrational kinetics considers vibrational levels up to v = 41 and accounts for electron impact excitation and de-excitation (e-V), vibration-to-translation relaxation (V-T) in collisions with O2 molecules and O atoms, vibration-to-vibration energy exchanges (V-V), excitation of electronically excited states, dissociative electron attachment, and electron impact dissociation. Measurements were performed at pressures of 10–80 mTorr (1.33 and 10.67 Pa) and radio frequency (13.56 MHz) powers up to 500 W. The simulation results are compared with the absolute densities in each O2 vibrational level obtained by high sensitivity absorption spectroscopy measurements of the Schumann–Runge bands for O2(X, v = 4–18), O(3 P) atom density measurements by two-photon absorption laser induced fluorescence (TALIF) calibrated against Xe, and laser photodetachment measurements of the O‑ negative ions. The highly excited O2(X, v) distribution exhibits a shape similar to a Treanor-Gordiets distribution, but its origin lies in electron impact e-V collisions and not in V-V up-pumping, in contrast to what happens in all other molecular gases known to date. The relaxation of vibrational quanta is mainly due to V-T energy-transfer collisions with O atoms and to electron impact dissociation of vibrationally excited molecules, e+O2(X, v)→O(3P)+O(3P).

Space Shuttle Crawler Transporter Vibration Analysis in Support of Rollout Fatigue Load Spectra Verification Program

NASA Technical Reports Server (NTRS)

Margasahayam, Ravi N.; Meyer, Karl A.; Nerolich, Shaun M.; Burton, Roy C.; Gosselin, Armand M.

2004-01-01

The Crawler Transporter (CT), designed and built for the Apollo Program in the 1960's and surpassing its initial operational life, has become an integral part of the Space Shuttle Program (SSP). The CT transports the Space Shuttle Vehicle (SSV) stack, atop the Mobile Launch Platform (MLP), from the Vehicle Assembly Building (VAB) to the launch pad. This support structure provides hydraulic jacking, leveling and load equalization for the 12 million pound stack on its 3.5-5.0 mile rollout to the launch pad. Major elements of the SSV, consisting of the orbiter, solid rocket boosters (SRB) and external tank (ET) have required fatigue analyses as part of the mission life certification. Compared to rollout vibration, the SSV sees relatively high vibration loads during launch, ascent, descent and landing phases of the mission. Although preliminary measured SRB vibration levels during rollout were of low amplitude and frequency, the duration of the rollout phase is typically high, from 5-6 hours. As part of an expanded mission life assessment, additional certification effort was initiated to define fatigue load spectra for rollout. This study addresses the CT vibration analyses in support of the rollout fatigue study. Structural models developed for modal and vibration analyses were used to identify unique CT, CT/MLP and CT/MLP/SRB vibration characteristics for comparison to instrumented rollout tests. Whereas the main structural and vibration characteristics of the SSV are well defined, minimum analytical and vibration test data on the Crawler Transporter were available. Unique vibration characteristics of the CT are attributable to the drive mechanism, hydraulic jacking system, structural framing and the CT-to-MLP support pad restraints. Initial tests performed on the CT/MLP/SRB configuration showed reasonable correlation with predicted mode shapes and frequencies.

Exposure to whole-body vibration and seat transmissibility in a large sample of earth scrapers.

PubMed

Salmoni, Alan; Cann, Adam; Gillin, Kent

2010-01-01

It is often difficult to access a large sample of vehicles in various work environments to evaluate worker exposure to vibration such as in construction and mining. Thus the main purpose of the present research was to test vibration exposure in a relatively large number of earth scrapers. The second aim was to assess vibration exposure values on seat transmissibility. 33earth scrapers were assessed for both exposure to whole-body vibration and seat transmissibility. Two triaxial accelerometers, one placed on the seat and one on the floor directly below the seat, were used to gather whole-body vibration values (a(w)). Each machine was tested for a minimum of three complete work cycles: idling, scraping, travelling full, dumping, travelling empty back to the scrape site. Results showed that idling and scraping produced low levels of vibration when compared to travelling and dumping. Second, when the a(w) values were compared to the EU safety standards for an eight hour work day, the data (z axis) exceeded the exposure action value (0.5 m/s2) in all machines, and the exposure limit value (1.15 m/s2) in some. Implications; Operators of the scrapers were being exposed to unsafe levels of whole-body vibration. When the seats were assessed to see whether they were attenuating operator exposure to vibration, many of the seat effective amplitude transmissibility (SEAT) values exceeded 1.0. This meant that some of the seats were actually amplifying the vibration present at the floor, particularly in the y axis. Travelways should be kept smooth, operating speeds reduced, and new seats, effective in all three axes, designed.

Vibration-reducing gloves: transmissibility at the palm of the hand in three orthogonal directions

PubMed Central

McDowell, Thomas W.; Dong, Ren G.; Welcome, Daniel E.; Xu, Xueyan S.; Warren, Christopher

2015-01-01

Vibration-reducing (VR) gloves are commonly used as a means to help control exposures to hand-transmitted vibrations generated by powered hand tools. The objective of this study was to characterise the vibration transmissibility spectra and frequency-weighted vibration transmissibility of VR gloves at the palm of the hand in three orthogonal directions. Seven adult males participated in the evaluation of seven glove models using a three-dimensional hand–arm vibration test system. Three levels of hand coupling force were applied in the experiment. This study found that, in general, VR gloves are most effective at reducing vibrations transmitted to the palm along the forearm direction. Gloves that are found to be superior at reducing vibrations in the forearm direction may not be more effective in the other directions when compared with other VR gloves. This casts doubts on the validity of the standardised glove screening test. Practitioner Summary This study used human subjects to measure three-dimensional vibration transmissibility of vibration-reducing gloves at the palm and identified their vibration attenuation characteristics. This study found the gloves to be most effective at reducing vibrations along the forearm direction. These gloves did not effectively attenuate vibration along the handle axial direction. PMID:24160755

Coherent control of the formation of cold heteronuclear molecules by photoassociation

NASA Astrophysics Data System (ADS)

de Lima, Emanuel F.

2017-01-01

We consider the formation of cold diatomic molecules in the electronic ground state by photoassociation of atoms of dissimilar species. A combination of two transition pathways from the free colliding pair of atoms to a bound vibrational level of the electronic molecular ground state is envisioned. The first pathway consists of a pump-dump scheme with two time-delayed laser pulses in the near-infrared frequency domain. The pump pulse drives the transition to a bound vibrational level of an excited electronic state, while the dump pulse transfers the population to a bound vibrational level of the electronic ground state. The second pathway takes advantage of the existing permanent dipole moment and employs a single pulse in the far-infrared domain to drive the transition from the unbound atoms directly to a bound vibrational level in the electronic ground state. We show that this scheme offers the possibility to coherently control the photoassociation yield by manipulating the relative phase and timing of the pulses. The photoassociation mechanism is illustrated for the formation of cold LiCs molecules.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shirkov, Leonid; Makarewicz, Jan, E-mail: jama@amu.edu.pl

An ab initio intermolecular potential energy surface (PES) has been constructed for the benzene-krypton (BKr) van der Waals (vdW) complex. The interaction energy has been calculated at the coupled cluster level of theory with single, double, and perturbatively included triple excitations using different basis sets. As a result, a few analytical PESs of the complex have been determined. They allowed a prediction of the complex structure and its vibrational vdW states. The vibrational energy level pattern exhibits a distinct polyad structure. Comparison of the equilibrium structure, the dipole moment, and vibrational levels of BKr with their experimental counterparts has allowedmore » us to design an optimal basis set composed of a small Dunning’s basis set for the benzene monomer, a larger effective core potential adapted basis set for Kr and additional midbond functions. Such a basis set yields vibrational energy levels that agree very well with the experimental ones as well as with those calculated from the available empirical PES derived from the microwave spectra of the BKr complex. The basis proposed can be applied to larger complexes including Kr because of a reasonable computational cost and accurate results.« less

Ground and flight test results of a total main rotor isolation system

NASA Technical Reports Server (NTRS)

Halwes, Dennis R.

1987-01-01

A six degree-of-freedom (DOF) isolation system using six LIVE units has been installed under an Army/NASA contract on a Bell 206LM helicopter. This system has been named the Total Rotor Isolation System, or TRIS. To determine the effectiveness of TRIS in reducing helicopter vibration, a flight verification study was conducted at Bell's Flight Research Center in Arlington, Texas. The flight test data indicate that the 4/rev vibration level at the pilot's seat were suppressed below the 0.04g level throughout the transition envelope. Flight tests indicate over 95% suppression of vibration level from the rotor hub to the pilot's seat. The TRIS installation was designed with a decoupled control system and has shown a significant improvement in aircraft flying qualities, such that it permitted the trimmed aircraft to be flown hands-off for a significant period of time, over 90 seconds. The TRIS flight test program has demonstrated a system that greatly reduces vibration levels of a current-generation helicopter, while significantly improving the flying qualities to a point where stability augmentation is no longer a requirement.

Car-Parrinello molecular dynamics study of the intramolecular vibrational mode-sensitive double proton-transfer mechanisms in porphycene.

PubMed

Walewski, Łukasz; Waluk, Jacek; Lesyng, Bogdan

2010-02-18

Car-Parrinello molecular dynamics simulations were carried out to help interpret proton-transfer processes observed experimentally in porphycene under thermodynamic equilibrium conditions (NVT ensemble) as well as during selective, nonequilibrium vibrational excitations of the molecular scaffold (NVE ensemble). In the NVT ensemble, the population of the trans form in the gas phase at 300 K is 96.5%, and of the cis-1 form is 3.5%, in agreement with experimental data. Approximately 70% of the proton-transfer events are asynchronous double proton transfers. According to the high resolution simulation data they consist of two single transfer events that rapidly take place one after the other. The average time-period between the two consecutive jumps is 220 fs. The gas phase reaction rate estimate at 300 K is 3.6 ps, which is comparable to experimentally determined rates. The NVE ensemble nonequilibrium ab initio MD simulations, which correspond to selective vibrational excitations of the molecular scaffold generated with high resolution laser spectroscopy techniques, exhibit an enhancing property of the 182 cm(-1) vibrational mode and an inhibiting property of the 114 cm(-1) one. Both of them influence the proton-transfer rate, in qualitative agreement with experimental findings. Our ab initio simulations provide new predictions regarding the influence of double-mode vibrational excitations on proton-transfer processes. They can help in setting up future programmable spectroscopic experiments for the proton-transfer translocations.

A disassembly-free method for evaluation of spiral bevel gear assembly

NASA Astrophysics Data System (ADS)

Jedliński, Łukasz; Jonak, Józef

2017-05-01

The paper presents a novel method for evaluation of assembly of spiral bevel gears. The examination of the approaches to the problem of gear control diagnostics without disassembly has revealed that residual processes in the form of vibrations (or noise) are currently the most suitable to this end. According to the literature, contact pattern is a complex parameter for describing gear position. Therefore, the task is to determine the correlation between contact pattern and gear vibrations. Although the vibration signal contains a great deal of information, it also has a complex spectral structure and contains interferences. For this reason, the proposed method has three variants which determine the effect of preliminary processing of the signal on the results. In Variant 2, stage 1, the vibration signal is subjected to multichannel denoising using a wavelet transform (WT), and in Variant 3 - to a combination of WT and principal component analysis (PCA). This denoising procedure does not occur in Variant 1. Next, we determine the features of the vibration signal in order to focus on information which is crucial regarding the objective of the study. Given the lack of unequivocal premises enabling selection of optimum features, we calculate twenty features, rank them and finally select the appropriate ones using an algorithm. Diagnostic rules were created using artificial neural networks. We investigated the suitability of three network types: multilayer perceptron (MLP), radial basis function (RBF) and support vector machine (SVM).

Signal Processing Methods for Removing the Effects of Whole Body Vibration upon Speech

NASA Technical Reports Server (NTRS)

Bitner, Rachel M.; Begault, Durand R.

2014-01-01

Humans may be exposed to whole-body vibration in environments where clear speech communications are crucial, particularly during the launch phases of space flight and in high-performance aircraft. Prior research has shown that high levels of vibration cause a decrease in speech intelligibility. However, the effects of whole-body vibration upon speech are not well understood, and no attempt has been made to restore speech distorted by whole-body vibration. In this paper, a model for speech under whole-body vibration is proposed and a method to remove its effect is described. The method described reduces the perceptual effects of vibration, yields higher ASR accuracy scores, and may significantly improve intelligibility. Possible applications include incorporation within communication systems to improve radio-communication systems in environments such a spaceflight, aviation, or off-road vehicle operations.

Metamaterial split ring resonator as a sensitive mechanical vibration sensor

NASA Astrophysics Data System (ADS)

Sikha Simon, K.; Chakyar, Sreedevi P.; Andrews, Jolly; Joseph V., P.

2017-06-01

This paper introduces a sensitive vibration sensor based on microwave metamaterial Split Ring Resonator (SRR) capable of detecting any ground vibration. The experimental setup consists of single Broad-side Coupled SRR (BCSRR) unit fixed on a cantilever capable of sensitive vibrations. It is arranged between transmitting and receiving probes of a microwave measurement system. The absorption level variations at the resonant frequency due to the displacement from the reference plane of SRR, which is a function of the strength of external mechanical vibration, is analyzed. This portable and cost effective sensor working on a single frequency is observed to be capable of detecting even very weak vibrations. This may find potential applications in the field of tamper-proofing, mining, quarrying and earthquake sensing.

Characteristics of Vibration that Alter Cardiovascular Parameters in Mice

PubMed Central

Li, Yao; Rabey, Karyne N; Schmitt, Daniel; Norton, John N; Reynolds, Randall P

2015-01-01

We hypothesized that short-term exposure of mice to vibration within a frequency range thought to be near the resonant frequency range of mouse tissue and at an acceleration of 0 to 1 m/s2 would alter heart rate (HR) and mean arterial pressure (MAP). We used radiotelemetry to evaluate the cardiovascular response to vibration in C57BL/6 and CD1 male mice exposed to vertical vibration of various frequencies and accelerations. MAP was consistently increased above baseline values at an acceleration near 1 m/s2 and a frequency of 90 Hz in both strains, and HR was increased also in C57BL/6 mice. In addition, MAP increased at 80 Hz in individual mice of both strains. When both strains were analyzed together, mean MAP and HR were increased at 90 Hz at 1 m/s2, and HR was increased at 80 Hz at 1 m/s2. No consistent change in MAP or HR occurred when mice were exposed to frequencies below 80 Hz or above 90 Hz. The increase in MAP and HR occurred only when the mice had conscious awareness of the vibration, given that these changes did not occur when anesthetized mice were exposed to vibration. Tested vibration acceleration levels lower than 0.75 m/s2 did not increase MAP or HR at 80 or 90 Hz, suggesting that a relatively high level of vibration is necessary to increase these parameters. These data are important to establish the harmful frequencies and accelerations of environmental vibration that should be minimized or avoided in mouse facilities. PMID:26224436

Conceptual design of new metrology laboratories for the National Physical Laboratory, United Kingdom

NASA Astrophysics Data System (ADS)

Manning, Christopher J.

1994-10-01

The National Physical Laboratory is planning to house the Division of Mechanical and Optical Metrology and the Division of Material Metrology in a new purpose built laboratory building on its site at Teddington, London, England. The scientific staff were involved in identifying and agreeing the vibration performance requirements of the conceptual design. This was complemented by an extensive surgery of vibration levels within the existing facilities and ambient vibration studies at the proposed site. At one end of the site there is significant vibration input from road traffic. Some of the test equipment is also in itself a source of vibration input. These factors, together with normal occupancy inputs, footfalls and door slams, and a highly serviced building led to vibration being dominant in influencing the structural form. The resulting structural concept comprises three separate structural elements for vibration and geotechnical reasons. The laboratories most sensitive to disturbance by vibration are located at the end of the site farthest from local roads on a massive ground bearing slab. Less sensitive laboratories and those containing vibration sources are located on a massive slab in deep, piled foundations. A common central plant area is located alongside on its own massive slab. Medium sensitivity laboratories and offices are located at first floor level on a reinforced concrete suspended floor of maximum stiffness per unit mass. The whole design has been such as to permit upgrading of areas, eg office to laboratory; laboratory to `high sensitivity' laboratory, to cater for changes in future use of the building.

Ro-vibrational averaging of the isotropic hyperfine coupling constant for the methyl radical

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adam, Ahmad Y.; Jensen, Per, E-mail: jensen@uni-wuppertal.de; Yachmenev, Andrey

2015-12-28

We present the first variational calculation of the isotropic hyperfine coupling constant of the carbon-13 atom in the CH{sub 3} radical for temperatures T = 0, 96, and 300 K. It is based on a newly calculated high level ab initio potential energy surface and hyperfine coupling constant surface of CH{sub 3} in the ground electronic state. The ro-vibrational energy levels, expectation values for the coupling constant, and its temperature dependence were calculated variationally by using the methods implemented in the computer program TROVE. Vibrational energies and vibrational and temperature effects for coupling constant are found to be in verymore » good agreement with the available experimental data. We found, in agreement with previous studies, that the vibrational effects constitute about 44% of the constant’s equilibrium value, originating mainly from the large amplitude out-of-plane bending motion and that the temperature effects play a minor role.« less

State-to-State Mode Specificity: Energy Sequestration and Flow Gated by Transition State.

PubMed

Zhao, Bin; Sun, Zhigang; Guo, Hua

2015-12-23

Energy flow and sequestration at the state-to-state level are investigated for a prototypical four-atom reaction, H2 + OH → H + H2O, using a transition-state wave packet (TSWP) method. The product state distribution is found to depend strongly on the reactant vibrational excitation, indicating mode specificity at the state-to-state level. From a local-mode perspective, it is shown that the vibrational excitation of the H2O product derives from two different sources, one attributable to the energy flow along the reaction coordinate into the newly formed OH bond and the other due to the sequestration of the vibrational energy in the OH spectator moiety during the reaction. The analysis provided a unified interpretation of some seemingly contradicting experimental observations. It is further shown that the transfer of vibrational energy from the OH reactant to H2O product is gated by the transition state, accomplished coherently by multiple TSWPs with the corresponding OH vibrational excitation.

Vibrationally Excited HCN in the Luminous Infrared Galaxy NGC 4418

NASA Astrophysics Data System (ADS)

Sakamoto, Kazushi; Aalto, Susanne; Evans, Aaron S.; Wiedner, Martina C.; Wilner, David J.

2010-12-01

Infrared pumping and its effect on the excitation of HCN molecules can be important when using rotational lines of HCN to probe dense molecular gas in galaxy nuclei. We report the first extragalactic detection of (sub)millimeter rotational lines of vibrationally excited HCN, in the dust-enshrouded nucleus of the luminous infrared galaxy NGC 4418. We estimate the excitation temperature of Tvib ≈ 230 K between the vibrational ground and excited (v 2 = 1) states. This excitation is most likely due to infrared radiation. At this high vibrational temperature the path through the v 2 = 1 state must have a strong impact on the rotational excitation in the vibrational ground level, although it may not be dominant for all rotational levels. Our observations also revealed nearly confusion-limited lines of CO, HCN, HCO+, H13CN, HC15N, CS, N2H+, and HC3N at λ ~ 1 mm. Their relative intensities may also be affected by the infrared pumping.

A comparison of whole body vibration and moist heat on lower extremity skin temperature and skin blood flow in healthy older individuals

PubMed Central

Lohman, Everett B.; Sackiriyas, Kanikkai Steni Balan; Bains, Gurinder S.; Calandra, Giovanni; Lobo, Crystal; Nakhro, Daniel; Malthankar, Gauri; Paul, Sherwine

2012-01-01

Summary Background Tissue healing is an intricate process that is regulated by circulation. Heat modalities have been shown to improve skin circulation. Recent research supports that passive vibration increases circulation without risk of burns. Study purpose is to compare and determine effects of short duration vibration, moist heat, and a combination of the two on skin blood flow (SBF) and skin temperature (ST) in elderly, non-diabetic individuals following short-term exposure. Material/Methods Ten subjects, 3 female and 7 male (55–73 years of age), received two interventions over three days: 1 – Active vibration, 2 – passive vibration, 3 – moist heat, 4 – moist heat combined with passive vibration (MHPV), 5 – a commercial massaging heating pad, and 6 – no intervention. SBF and ST were measured using a MOOR Laser Doppler before and after the intervention and the third measurement were taken 10 minutes following. Results Mean SBF following a ten-minute intervention were significantly different in the combination of moist heat and passive vibration from the control, active vibration, and the commercial massaging heating pad. Compared to baseline measurements, this resulted in mean SBF elevation to 450% (at conclusion of 10 minutes of intervention) and 379% (10 minutes post). MHPV (p=0.02) showed significant changes in ST from the commercial massaging heating pad, passive vibration, and active vibration interventions. Conclusions SBF in the lower legs showed greatest increase with MHPV. Interventions should be selected that are low risk while increasing lower extremity skin blood flow. PMID:22739731

Discovery of Cellulose Surface Layer Conformation by Nonlinear Vibrational Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Libing; Fu, Li; Wang, Hong-fei

2017-03-14

Significant questions remain with respect to the structure and polymorphs of cellulose. These include the cellulose surface layers and the bulk crystalline core as well as the conformational differences. The Total Internal Reflection Sum Frequency Generation Vibrational Spectroscopy (TIR-SFG-VS) combined with the conventional SFG-VS (non-TIR) can help to resolve these questions by selectively characterizing the molecular structures of surface layers and the crystalline core of cellulose. From the SFG spectra in the C-H and O-H regions, we found that the surface layers of Avicel are essentially amorphous; while the surface layers of Iβ cellulose are crystalline but with different structuralmore » and spectroscopic signatures than that of its crystalline core. This work demonstrates the capacity of TIR and Non-TIR SFG-VS tools in selectively studying the structures and polymorphs of cellulose. In addition, these results also suggest that the assignments of major vibrational peaks for cellulose need to be further determined.« less

Mapping quadrupole collectivity in the Cd isotopes: The breakdown of harmonic vibrational motion

NASA Astrophysics Data System (ADS)

Garrett, P. E.; Green, K. L.; Bangay, J.; Varela, A. Diaz; Sumithrarachchi, C. S.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D. S.; Bianco, L.; Colosimo, S.; Cross, D. S.; Demand, G. A.; Finlay, P.; Garnsworthy, A. B.; Grinyer, G. F.; Hackman, G.; Kulp, W. D.; Leach, K. G.; Morton, A. C.; Orce, J. N.; Pearson, C. J.; Phillips, A. A.; Schumaker, M. A.; Svensson, C. E.; Triambak, S.; Wong, J.; Wood, J. L.; Yates, S. W.

2011-10-01

The stable Cd isotopes have long been used as paradigms for spherical vibrational motion. Extensive investigations with in-beam γ spectroscopy have resulted in very-well-established level schemes, including many lifetimes or lifetime limits. A programme has been initiated to complement these studies with very-high-statistics β decay using the 8π spectrometer at the TRIUMF radioactive beam facility. The decays of 112In and 112Ag have been studied with an emphasis on the observation of, or the placement of stringent limits on, low-energy branches between potential multi-phonon levels. A lack of suitable 0+ or 2+ three-phonon candidates has been revealed. Further, the sum of the B(E2) strength from spin 0+ and 2+ states up to 3 MeV in excitation energy to the assigned two-phonon levels falls far short of the harmonic-vibrational expectations. This lack of strength points to the failing of collective models based on vibrational phonon structures.

Echo planar imaging at 4 Tesla with minimum acoustic noise.

PubMed

Tomasi, Dardo G; Ernst, Thomas

2003-07-01

To minimize the acoustic sound pressure levels of single-shot echo planar imaging (EPI) acquisitions on high magnetic field MRI scanners. The resonance frequencies of gradient coil vibrations, which depend on the coil length and the elastic properties of the materials in the coil assembly, were measured using piezoelectric transducers. The frequency of the EPI-readout train was adjusted to avoid the frequency ranges of mechanical resonances. Our MRI system exhibited two sharp mechanical resonances (at 720 and 1220 Hz) that can increase vibrational amplitudes up to six-fold. A small adjustment of the EPI-readout frequency made it possible to reduce the sound pressure level of EPI-based perfusion and functional MRI scans by 12 dB. Normal vibrational modes of MRI gradient coils can dramatically increase the sound pressure levels during echo planar imaging (EPI) scans. To minimize acoustic noise, the frequency of EPI-readout trains and the resonance frequencies of gradient coil vibrations need to be different. Copyright 2003 Wiley-Liss, Inc.

Computational vibrational study on coordinated nicotinamide

NASA Astrophysics Data System (ADS)

Bolukbasi, Olcay; Akyuz, Sevim

2005-06-01

The molecular structure and vibrational spectra of zinc (II) halide complexes of nicotinamide (ZnX 2(NIA) 2; X=Cl or Br; NIA=Nicotinamide) were investigated by computational vibrational study and scaled quantum mechanical (SQM) analysis. The geometry optimisation and vibrational wavenumber calculations of zinc halide complexes of nicotinamide were carried out by using the DFT/RB3LYP level of theory with 6-31G(d,p) basis set. The calculated wavenumbers were scaled by using scaled quantum mechanical (SQM) force field method. The fundamental vibrational modes were characterised by their total energy distribution. The coordination effects on nicotinamide through the ring nitrogen were discussed.

The effect of inclined soil layers on surface vibration from underground railways using a semi-analytical approach

NASA Astrophysics Data System (ADS)

Jones, S.; Hunt, H.

2009-08-01

Ground vibration due to underground railways is a significant source of disturbance for people living or working near the subways. The numerical models used to predict vibration levels have inherent uncertainty which must be understood to give confidence in the predictions. A semi-analytical approach is developed herein to investigate the effect of soil layering on the surface vibration of a halfspace where both soil properties and layer inclination angles are varied. The study suggests that both material properties and inclination angle of the layers have significant effect (± 10dB) on the surface vibration response.

Acoustic vibrations of metal nano-objects: Time-domain investigations

NASA Astrophysics Data System (ADS)

Crut, Aurélien; Maioli, Paolo; Del Fatti, Natalia; Vallée, Fabrice

2015-01-01

Theoretical and time-domain experimental investigations of the vibrational acoustic response of nano-objects are described focusing on metallic ones. Acoustic vibrations are modeled using a macroscopic-like approach based on continuum mechanics with the proper boundary conditions, a model which yields results in excellent agreement with the experimental ones and those of atomistic calculations, down to the nanometric scale. Vibrational mode excitation and detection mechanisms and the associated mode selection in ultrafast pump-probe spectroscopy are discussed, and the measured time-dependent signals in single and ensemble of nanoparticles modeled. The launched modes, their period and their damping rate are compared to experimental results obtained on ensembles of nano-objects with different composition, morphology and environment, and with size ranging from one to hundreds of nanometers. Recent extension of time-domain spectroscopy to individual nano-objects has shed new light on the vibrational responses of isolated nanoparticles, in particular on their damping, but also raises questions on the origin of its large particle to particle dispersion.

Modeling the night-time CO2 4.3 μm emissions in the mesosphere/lower thermosphere

NASA Astrophysics Data System (ADS)

Panka, Peter; Kutepov, Alexander; Feofilov, Artem; Rezac, Ladislav; Janches, Diego

2016-04-01

We present a detailed non-LTE model of the night-time CO2 4.3 μm emissions in the MLT. The model accounts for various mechanisms of the non-thermal excitation of CO2 molecules and both for inter- and intra-molecular vibrational-vibrational (VV) and vibrational-translational (VT) energy exchanges. In this model, we pay a specific attention to the transfer of vibrational energy of OH(ν), produced in the chemical reaction H + O3, to the CO2(ν3) vibrational mode. With the help of this model, we simulated a set of non-LTE 4.3 μm MLT limb emissions for typical atmospheric scenarios and compared the vertical profiles of integrated radiances with the corresponding SABER/TIMED observations. The implications, which follow from this comparison, for selecting non-LTE model parameters (rate coefficients), as well as for the night-time CO2 density retrieval in the MLT are discussed.

Optimum vibration control of flexible beams by piezo-electric actuators

NASA Technical Reports Server (NTRS)

Baz, A.; Poh, S.; Studer, P.

1988-01-01

The utilization of piezoelectric actuators in controlling the structural vibrations of flexible beams is examined. A Modified Independent Modal Space Control (MIMSC) method is devised to enable the selection of the optimal location, control gains and excitation voltage of the piezoelectric actuators in a way that would minimize the amplitudes of vibrations of beams to which these actuators are bonded, as well as the input control energy necessary to suppress these vibrations. The developed method accounts for the effects that the piezoelectric actuators have on changing the elastic and inertial properties of the flexible beams. Numerical examples are presented to illustrate the application of the developed MIMSC method in minimizing the structural vibrations of beams of different materials when subjected to different loading and end conditions using ceramic or polymeric piezoelectric actuators. The obtained results emphasize the importance of the devised method in designing more realistic active control systems for flexible beams, in particular, and large flexible structures in general.

Optimum vibration control of flexible beams by piezo-electric actuators

NASA Technical Reports Server (NTRS)

Baz, A.; Poh, S.

1987-01-01

The utilization of piezoelectric actuators in controlling the structural vibrations of flexible beams is examined. A Modified Independent Modal Space Control (MIMSC) method is devised to enable the selection of the optimal location, control gains and excitation voltage of the piezoelectric actuators in a way that would minimize the amplitudes of vibrations of beams to which these actuators are bonded, as well as the input control energy necessary to suppress these vibrations. The developed method accounts for the effects that the piezoelectric actuators have on changing the elastic and inertial properties of the flexible beams. Numerical examples are presented to illustrate the application of the developed MIMSC method in minimizing the structural vibrations of beams of different materials when subjected to different loading and end conditions using ceramic or polymeric piezoelectric actuators. The obtained results emphasize the importance of the devised method in designing more realistic active control systems for flexible beams, in particular, and large flexible structures in general.

Reverse transduction measured in the living cochlea by low-coherence heterodyne interferometry.

PubMed

Ren, Tianying; He, Wenxuan; Barr-Gillespie, Peter G

2016-01-06

It is generally believed that the remarkable sensitivity and frequency selectivity of mammalian hearing depend on outer hair cell-generated force, which amplifies sound-induced vibrations inside the cochlea. This 'reverse transduction' force production has never been demonstrated experimentally, however, in the living ear. Here by directly measuring microstructure vibrations inside the cochlear partition using a custom-built interferometer, we demonstrate that electrical stimulation can evoke both fast broadband and slow sharply tuned responses of the reticular lamina, but only a slow tuned response of the basilar membrane. Our results indicate that outer hair cells can generate sufficient force to drive the reticular lamina over all audible frequencies in living cochleae. Contrary to expectations, the cellular force causes a travelling wave rather than an immediate local vibration of the basilar membrane; this travelling wave vibrates in phase with the reticular lamina at the best frequency, and results in maximal vibration at the apical ends of outer hair cells.

Whole-body vibration and postural stress among operators of construction equipment: a literature review.

PubMed

Kittusamy, N Kumar; Buchholz, Bryan

2004-01-01

Operators of construction equipment perform various duties at work that expose them to a variety of risk factors that may lead to health problems. A few of the health hazards among operators of construction equipment are: (a) whole-body vibration, (b) awkward postural requirements (including static sitting), (c) dust, (d) noise, (e) temperature extremes, and (f) shift work. It has been suggested that operating engineers (OEs) are exposed to two important risk factors for the development of musculoskeletal disorders: whole-body vibration and non-neutral body postures. This review evaluates selected papers that have studied exposure to whole-body vibration and awkward posture among operators of mobile equipment. There have been only few studies that have specifically examined exposure of these risk factors among operators of construction equipment. Thus other studies from related industry and equipment were reviewed as applicable. In order to better understand whole-body vibration and postural stress among OEs, it is recommended that future studies are needed in evaluating these risk factors among OEs.

Synthesis, vibrational, NMR, quantum chemical and structure-activity relation studies of 2-hydroxy-4-methoxyacetophenone.

PubMed

Arjunan, V; Devi, L; Subbalakshmi, R; Rani, T; Mohan, S

2014-09-15

The stable geometry of 2-hydroxy-4-methoxyacetophenone is optimised by DFT/B3LYP method with 6-311++G(∗∗) and cc-pVTZ basis sets. The structural parameters, thermodynamic properties and vibrational frequencies of the optimised geometry have been determined. The effects of substituents (hydroxyl, methoxy and acetyl groups) on the benzene ring vibrational frequencies are analysed. The vibrational frequencies of the fundamental modes of 2-hydroxy-4-methoxyacetophenone have been precisely assigned and analysed and the theoretical results are compared with the experimental vibrations. 1H and 13C NMR isotropic chemical shifts are calculated and assignments made are compared with the experimental values. The energies of important MO's, the total electron density and electrostatic potential of the compound are determined. Various reactivity and selectivity descriptors such as chemical hardness, chemical potential, softness, electrophilicity, nucleophilicity and the appropriate local quantities are calculated. Copyright © 2014 Elsevier B.V. All rights reserved.

Electronic and vibrational spectroscopy and vibrationally mediated photodissociation of V+(OCO).

PubMed

Citir, Murat; Altinay, Gokhan; Metz, Ricardo B

2006-04-20

Electronic spectra of gas-phase V+(OCO) are measured in the near-infrared from 6050 to 7420 cm(-1) and in the visible from 15,500 to 16,560 cm(-1), using photofragment spectroscopy. The near-IR band is complex, with a 107 cm(-1) progression in the metal-ligand stretch. The visible band shows clearly resolved vibrational progressions in the metal-ligand stretch and rock, and in the OCO bend, as observed by Brucat and co-workers. A vibrational hot band gives the metal-ligand stretch frequency in the ground electronic state nu3'' = 210 cm(-1). The OCO antisymmetric stretch frequency in the ground electronic state (nu1'') is measured by using vibrationally mediated photodissociation. An IR laser vibrationally excites ions to nu1'' = 1. Vibrationally excited ions selectively dissociate following absorption of a second, visible photon at the nu1' = 1 <-- nu1'' = 1 transition. Rotational structure in the resulting vibrational action spectrum confirms that V+(OCO) is linear and gives nu1'' = 2392.0 cm(-1). The OCO antisymmetric stretch frequency in the excited electronic state is nu1' = 2368 cm(-1). Both show a blue shift from the value in free CO2, due to interaction with the metal. Larger blue shifts observed for complexes with fewer ligands agree with trends seen for larger V+(OCO)n clusters.

Limb segment vibration modulates spinal reflex excitability and muscle mRNA expression after spinal cord injury

PubMed Central

Chang, Shuo-Hsiu; Tseng, Shih-Chiao; McHenry, Colleen L.; Littmann, Andrew E.; Suneja, Manish; Shields, Richard K.

2012-01-01

Objective We investigated the effect of various doses of vertical oscillation (vibration) on soleus H-reflex amplitude and post-activation depression in individuals with and without SCI. We also explored the acute effect of short-term limb vibration on skeletal muscle mRNA expression of genes associated with spinal plasticity. Methods Six healthy adults and five chronic complete SCI subjects received vibratory stimulation of their tibia over three different gravitational accelerations (0.3g, 0.6g, and 1.2g) at a fixed frequency (30 Hz). Soleus H-reflexes were measured before, during, and after vibration. Two additional chronic complete SCI subjects had soleus muscle biopsies 3 h following a single bout of vibration. Results H-reflex amplitude was depressed over 83% in both groups during vibration. This vibratory-induced inhibition lasted over 2 min in the control group, but not in the SCI group. Post-activation depression was modulated during the long-lasting vibratory inhibition. A single bout of mechanical oscillation altered mRNA expression from selected genes associated with synaptic plasticity. Conclusions Vibration of the lower leg inhibits the H-reflex amplitude, influences post-activation depression, and alters skeletal muscle mRNA expression of genes associated with synaptic plasticity. Significance Limb segment vibration may offer a long term method to reduce spinal reflex excitability after SCI. PMID:21963319